EVALUATION KIT AVAILABLE MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators General Description Benefits and Features The MAX77387 provides a high-efficiency solution for smartphone camera flash applications by integrating a dual-phase 2A PWM DC-DC step-up converter and two programmable 1A high side, low-dropout LED current regulators for flash and torch functions. An I2C interface provides flexible control of the step-up converter, torch, flash mode selection, and torch/flash safety timer duration settings. S Input Supply of 2.5V to 5.5V with Full Functionality The IC operates down to 2.5V, making it futureproof for new battery technologies. The step-up converter features an internal switching MOSFET and synchronous rectifier to improve efficiency and minimize external component count. Dual-phase operation ensures low output ripple and provides smallest possible solution size. The IC also includes dual high-side high-current regulators for supporting torch and flash modes. The high-current regulators can source up to 1A each in flash mode and up to 250mA each in torch mode. The high-current regulators can be combined to drive a single LED up to 2A in flash mode and up to 500mA in torch mode. The output voltage can be adaptively controlled, boosting only as high as necessary to support the required LED forward voltage. Adaptive mode can be used in either flash or torch mode and works with both DAC and/or PWM dimming control schemes. This approach reduces IC power dissipation by optimizing the boost ratio and by minimizing the losses in the current regulators. The IC includes control for external NTC, dual Tx mask, flash strobe, and torch enable functions. This allows for flexible control of the IC. Additionally, the IC includes MAXFLASH 2.0 function that adaptively reduces flash current during low battery conditions to help prevent system undervoltage lockup. Other features include shorted LED detection, overvoltage and thermal shutdown protection, and low-power standby and shutdown modes. The IC is available in a 20-bump, 0.4mm pitch WLP package (2.1mm x 1.73mm). Applications S Dual-Phase Interleave Step-Up DC-DC Converter True Shutdown Output 2A Guaranteed Output Current for VIN > 2.7V and VOUT P 4.0V Adaptive Output Voltage Regulation to Ensure Industry's Highest System Efficiency Over 90% Peak Efficiency 3.125% Minimum Duty Cycle Skip Mode Capable On-Chip Power MOSFET and Synchronous Rectifier Up to 4MHz PWM Switching Frequency per Phase Small 0.47FH Inductor per Phase S High-Side Torch/Flash LED Current Regulator I2C Programmable Flash Output Current (15.625mA to 1000mA in 15.625mA Steps) I2C Programmable Torch Output Current (3.91mA to 250mA in 3.91mA Steps for NonPWM dimming) (125mA to 1000mA in 125mA Steps for PWM Dimming with Programmable Duty Cycle from 3.125% to 25% in 3.125% steps) Low-Dropout Voltage (80mV typ) at 1000mA S I2C-Programmable Flash Safety Timer S I2C-Programmable Torch Safety Timer and Optional Disabled Torch Timer S Dual Independent TX_MASK Inputs for Limiting Flash Current During Tx Events S Open/Shorted LED Detection S NTC Monitoring for LED Protection S Overvoltage Protection S MAXFLASH 2.0 Preventing System Undervoltage Lockup S Thermal Shutdown Protection S < 1A Shutdown Current S 20-Bump, 0.4mm Pitch 2.1mm x 1.73mm WLP Cell Phones and Smartphones Tablets Ordering Information appears at end of data sheet. Simplified Block Diagram appears at end of data sheet. *Patent protected PCT/US2008/075643. For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX77387.related. For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maximintegrated.com. 19-6282; Rev 0; 7/12 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators TABLE OF CONTENTS General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Package Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Bump Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Bump Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Shutdown Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Standby Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Active Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Torch Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Flash Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Adaptive Output Voltage Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Current Regulator Voltage Headroom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Step-Up Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Dual-Phase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Skip Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Current Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Switching Frequency Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Overvoltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 True Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 End of Trigger Event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Gain Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Low-Side Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Current Regulator LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Maxim Integrated 2 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators TABLE OF CONTENTS (CONTINUED) DAC and PWM Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 DAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 PWM Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 DAC and PWM Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Ramp Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Torch and Flash Safety Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 MAXFLASH Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 TX_MASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 NTC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Short and Open LED Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 I2C Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 I2C Slave Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 I2C Bit Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 START and STOP Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Write Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Read Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Programming the I2C registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Output Voltage Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Output Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Chip Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Maxim Integrated 3 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators LIST OF FIGURES Figure 1. Detailed Block Diagram and Typical Application Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Figure 2. Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Figure 3. DC-DC Converter Soft-Start for DCDC_MODE = 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 4. DC-DC Converter Soft-Start for DCDC_MODE = 01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 5 DC-DC Converter Soft-Start for DCDC_MODE = 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Figure 6. DC-DC Converter Soft-Start for DCDC_MODE = 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Figure 7. Driving Two LED Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Figure 8. Driving a Single LED Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Figure 9. Maximum Flash Timer Mode/Disabled Torch Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Figure 10. One-Shot Torch /Flash Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Figure 11. TX1_MASK or TX2_MASK During Flash Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Figure 12. TX1_MASK and TX2_MASK Occurring at Same Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Figure 13. 2-Wire Serial Interface Timing Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Figure 14. Bit Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Figure 15. START and STOP Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Figure 16. Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Figure 17. Write to the IC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Figure 18. Read from the IC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Figure 19. Output Capacitor Star Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Figure 20. 20-Bump WLP Recommended Layout for 2x1.5A Input Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Maxim Integrated 4 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators LIST OF TABLES Table 1. I2C Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Table 2. CHIP_ID1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Table 3. CHIP_ID2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Table 4. STATUS1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Table 5. STATUS2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Table 6. IFLASH1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Table 7. IFLASH2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Table 8. ITORCH1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Table 9. ITORCH2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Table 10. MODE_SEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Table 11. TX1_MASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Table 12. TX2_MASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Table 13. FLASH_RAMP_SEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Table 14. TORCH_RAMP_SEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Table 15. FLASH_TMR_CNTL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Table 16. TORCH_TMR_CNTL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Table 17. MAXFLASH1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Table 18. MAXFLASH2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Table 19. MAXFLASH3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Table 20. MAXFLASH4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Table 21. NTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Table 22. DCDC_CNTL1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Table 23. DCDC_CNTL2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Table 24. DCDC_LIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Table 25. DCDC_OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Table 26. DCDC_OUT_MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Table 27. Maximum Output Voltage for 2A Output Current as a Function of VIN and IPEAK . . . . . . . . . . . . . . . . . . 71 Table 28. Maximum Output Voltage for 1.5A Output Current as a Function of VINand IPEAK . . . . . . . . . . . . . . . . . 72 Table 29. Maximum Output Voltage for 1.0A Output Current as a Function of VIN and IPEAK . . . . . . . . . . . . . . . . 73 Table 30. Suggested Inductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Table 31. Suggested Input Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Table 32. Suggested Output Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Maxim Integrated 5 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ABSOLUTE MAXIMUM RATINGS VDD, IN, REG_IN to AGND....................................-0.3V to +6.0V OUT_A, OUT_B to PGND_A, PGND_B.................-0.3V to +6.0V LX_A to PGND_A........................................ -0.3V to VOUT + 0.3V LX_B to PGND_B........................................ -0.3V to VOUT + 0.3V FLED1, FLED2 to AGND........................-0.3V to VREG_IN + 0.3v TX1_MASK, TX2_MASK, TORCH_EN, NTC to AGND............................................ -0.3V to VIN + 0.3V SDA, SCL, FLASH_STB to AGND................. -0.3V to VIN + 0.3V AGND to PGND_A, PGND_B................................-0.3V to +0.3V ILX_A, ILX_B Current (rms) per Phase.................................2.0A Continuous Power Dissipation (TA = +70NC) (derate 21.7mW/NC above +70NC).............................1736mW Operating Temperature....................................... -40NC to +85NC Junction Temperature......................................................+150NC Storage Temperature Range............................. -65NC to +150NC Soldering Temperature (reflow) (Note 1).........................+260NC Note 1: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board level solder attach and rework. This limit permits only the use of the solder profiles recommended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection reflow. Preheating is required. Hand or wave soldering is not allowed. PACKAGE THERMAL CHARACTERISTICS (Note 2) WLP Junction to Ambient Thermal Resistance (qJA)...........46C/W Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS GENERAL IN Operating Voltage Range 2.5 5.5 V VDD Operating Voltage Range 1.62 3.6 V IN Undervoltage Lockout (IN_UVLO) Threshold VIN falling, 60mV (typ) hysteresis 2.10 2.20 2.30 V VDD Under voltage Lockout (VDD_UVLO) Threshold VDD falling 0.65 0.9 1.0 V IN Shutdown Supply Current VIN = 5.5V, VDD = 0V TA = +25NC 0.01 1 TA = +85NC 0.1 VDD Standby Supply Current VIN = 5.5V, VDD = VSDA = VSCL = 3.6V, DCDC_MODE = 00 TA = +25NC 0.01 TA = +85NC 0.1 IN Standby Supply Current VIN = 5.5V, VDD = VSCL = VSDA = 3.6V, DCDC_MODE = 00, DC-DC converter and current regulators are off TA = -40NC to +85NC 1.5 Maxim Integrated 1 5 FA FA FA 6 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS LOGIC INTERFACE VDD = 1.62V to 3.6V SDA, SCL, FLASH_STB 0.7 x VDD VDD + 0.3V V VIN = 2.5V to 5.5V TORCH_EN, TX1_MASK, TX2_MASK 1.25 VIN + 0.3V V VDD = 1.62V to 3.6V SDA, SCL, FLASH_STB 0.4 VIN = 2.5V to 5.5V TORCH_EN, TX1_MASK, TX2_MASK 0.4 VDD = 1.62V to 3.6V FLASH_STB_PD = 1 FLASH_STB VIN = 2.5V to 5.5V TORCH_EN_PD = 1, TX1_MASK_PD = 1, TX2_MASK_PD = 1 TORCH_EN, TX1_MASK, TX2_MASK 400 800 1600 VDD = 1.62V to 3.6V, FLASH_STB_PD = 0 TA = +25NC -1 0.01 +1 VIN = 2.5V to 5.5V TORCH_EN_PD = 0, TX1_MASK_PD = 0, TX2_MASK_PD = 0 TA = +25NC Logic Input High Voltage Logic Input Low Voltage Pulldown Resistor Logic Input Current V 400 1600 kI 0.1 TA = +85NC TA = +85NC 800 -1 0.01 +1 FA 0.1 LOGIC INTERFACE TIMING FLASH_STB Enable Delay in Active Mode (tFLASH_EN_ACTIV) See Figure 4, from FLASH_STB rising edge until start of current regulator ramp up (Note 4) 5 Fs TORCH_EN Enable Delay in Active Mode (tTORCH_EN_ACTIV) See Figure 4, from TORCH_EN rising edge until start of current regulator ramp up (Note 4) 5 Fs FLASH_STB Enable Delay in Standby Mode (tFLASH_STB_STDBY) See Figure 3, from FLASH_STB rising edge until start of precharge of the output (Note 4) 30 Fs TORCH_EN Enable Delay in Standby Mode (tTORCH_EN_STDBY) See Figure 3, from TORCH_EN rising edge until start of precharge of the output (Note 4) 30 Fs Precharging of Output (tOUT_PCHG) See Figures 3-6, VIN = 3.6, COUT = 10FF, charging the output from 0V until LX starts switching (Note 4) 600 Fs Maxim Integrated 7 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS Soft-Start Time Duration, (tDCDC_SS) See Figures 3, 4, and 5 (Note 4) TX_MASK Trigger to Reduced Output Current (tTX_MASK_EN) Standby to Active Mode (tSTDBY2ACTIV) MIN TYP MAX UNITS DCDC_SS x8 Fs See Figures 9 and 10 From TX1_MASK, TX2_MASK triggered until output current is at reduced output current (Note 4) 7 Fs See Figures 5 and 6 Time to transition from standby to active mode (Note 4) 25 Fs I2C INTERFACE (Note 4) SDA Output Low Voltage ISDA = 3mA 0.03 I2C Clock Frequency 0.4 V 400 kHz Bus-Free Time Between START and STOP tBUF 1.3 Hold Time Repeated START Condition tHD_STA 0.6 0.1 Fs SCL Low Period tLOW 1.3 0.2 Fs SCL High Period tHIGH 0.6 0.2 Fs Setup Time Repeated START Condition tSU_STA 0.6 0.1 Fs SDA Hold Time tHD_DAT 0 -0.01 Fs SDA Setup Time tSU_DAT 100 50 ns Setup Time for STOP Condition tSU_STO 0.6 0.1 Fs OUT Voltage Range Adaptive controlled 2.3 Output Adaptive Regulation Step Size Smallest step size when output voltage is in adaptive regulation VADPT_REG_STEP Fs STEP-UP DC-DC CONVERTER Digital Overvoltage Protection (OVP_D) Analog Overvoltage Protection Output Threshold for Minimum Duty Cycle to Bypass Mode Maxim Integrated When operating in adaptive mode 5.2 6.25 OVP_TH = 00 0x140h (4.3V) OVP_TH = 01 0x170h (4.6V) OVP_TH = 10 0x1A0h (4.9V) OVP_TH = 11 0x1D0h (5.2V) mV 9-bit digital code OVP_TH = 00 4.35 4.5 4.65 OVP_TH = 01 4.65 4.8 4.95 OVP_TH = 10 4.95 5.1 5.25 OVP_TH = 11 5.25 5.4 5.55 VOUT_MIND Output voltage where the DC-DC converter goes from operating at minimum duty cycle to dropout operation, during a disabling of the DC-DC converter, DCDC_MODE = 00 VIN + 200mV V V V 8 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS Output Threshold for Dropout Operation to OFF Mode VOUT_OFF Output voltage where the DC-DC converter goes from operating in dropout mode to true shutdown, during a disabling of the DC-DC converter, DCDC_MODE = 00 VIN + 150mV V Charge Mode Comparator Threshold Output voltage where the DC-DC converter goes from operating at minimum duty cycle to soft start. VIN 300mV V Adaptive Output Step Time Time between sampling of adaptive regulation during soft-start (Note 5) 1 Time between sampling of adaptive regulation (Note 5) 8 VOUT = 4.5V, IOUT = 0mA, switching 4MHz PWM mode dual-phase operation (Note 2) 14 VOUT = 4.5V, IOUT = 0mA, switching 2MHz PWM mode dual-phase operation (Note 2) 15 IN Supply Current mA VOUT = 4.5V, IOUT = 0mA, no switching (skip mode) Low-Side Current Limit (Static Limits) (Phases A and B) Current Sharing Fs 450 FA DCDC_ILIM = 00 1.11 1.25 1.37 DCDC_ILIM = 01 1.35 1.5 1.65 DCDC_ILIM = 10 1.57 1.75 1.93 DCDC_ILIM = 11 1.80 2.0 2.20 Delta current between phase A and phase B (Note 4), excluding external components Phase A Zero-Crossing Threshold (Static, Phases A and B) A 0 % 120 mA LX_ High-Side On-Resistance (Phases A and B) LX_ to OUT_, ILX_ = -200mA, VOUT = 3.6V 130 185 mI LX_ Low-Side On-Resistance (Phases A and B) LX_ to PGND_, ILX_ = 200mA, VOUT = 3.6V 100 160 mI VIN = 3.4V, VOUT = 4.5V, enhanced mode (DCDC_GAIN = 1) (for adaptive mode only) (Note 4) 50 mV/A VIN = 3.4V, VOUT = 4.5V, enhanced mode (DCDC_GAIN = 1) (for program mode only) (Note 4) 100 mV/A Load Regulation TA = +25NC 0.1 TA = +85NC 0.1 LX_ Leakage (Phase A, Phase B) VLX_ = 5.5V Operating Frequency (Phase A, Phase B) DCDC_OPERATION[2:0] = 010 TA = -40NC to +85NC Maximum Duty Cycle (Phase A, Phase B) DCDC_OPERATION[2:0] = 011 Minimum Duty Cycle Maxim Integrated During non-skip mode (DCDC_OPERATION[2:0] = 011) During skip mode (Note 4) 3.90 4.0 70 2 4.10 FA MHz % 3.3 % 0 % 9 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS LED CURRENT SOURCE DRIVERS REG_IN Supply Current (FLED1, FLED2) FLED_ enabled in torch mode with PWM dimming set to maximum current setting, supply current measured during off period of PWM cycle 100 FA IN Supply Current (FLED1, FLED2) FLED_ enabled in torch mode with PWM dimming set to maximum current setting, supply current measured during off period of PWM cycle 25 FA FLED_ enabled in flash mode, current range in 15.625mA steps LED Current Setting Range (FLED1, FLED2) 15.625 1000 FLED_ enabled in torch mode, with DAC mode active, current range in 3.91mA steps 3.91 250 FLED_ enabled in torch mode with PWM dimming active, current range in 125mA steps 125.0 1000 PWM Dimming Duty Cycle Setting FLED_ enabled in torch mode with PWM dimming active, Range duty cycle range in 3.125% steps (Note 5) 3.125 25 FREQ_PWM[1:0] = 00 (Note 5) 7.8 PWM Dimming Frequency Setting FREQ_PWM[1:0] = 01 (Note 5) Range FREQ_PWM[1:0] = 10 (Note 5) 1.9 0.488 FREQ_PWM[1:0] = 11 (Note 5) 0.122 mA % kHz LED Peak Current Overshoot FLED_ enabled in torch mode with PWM dimming set to maximum current setting, maximum LED current overshoot during initial ramping up (Note 4) 10 % LED Current Settling Time FLED_ enabled in torch mode with PWM dimming set to maximum current setting. Time for LED current to settle to less than 10% from nominal setting (not including ramp time) (Note 4) 6 Fs LED Current Accuracy Flash Mode or Torch Mode with PWM Dimming (FLED1, FLED2) LED Current Accuracy Torch Mode (FLED1, FLED2) Maxim Integrated 625mA to 1000mA -5 +5 218.75mA to 609.375mA -7 +7 62.5mA to 203.125mA -10 +10 31.25mA to 46.875mA -12 +12 15.625mA -14 +14 156.25 to 250mA -5 +5 54.6875mA to 152.34375mA -7 +7 15.625mA to 50.78125mA -10 +10 7.8125mA to 11.71875mA -12 +12 3.91mA -14 +14 % % 10 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS MIN TYP LED Current Dropout Voltage Flash Mode or Torch Mode with PWM Dimming (FLED1, FLED2) 1000mA setting at -10% 1000mA setting at -1% (Note 4) 100 LED Current Dropout Voltage Torch Mode (FLED1, FLED2) 250mA setting at -10% 80 250mA setting at -1% (Note 4) 100 LED Adaptive Mode Threshold Voltage Setting Range (FLED1, FLED2) LED Leakage Current REG_IN UVLO Voltage MAX UNITS 80 mV FLED_ enabled in flash mode or torch mode REG_IN = 5.5V, FLED_ = 0V DCDC_ADPT_REG = 00 120 DCDC_ADPT_REG = 01 150 DCDC_ADPT_REG = 10 180 DCDC_ADPT_REG = 11 210 TA = +25NC 0.1 TA = +85NC 1 Minimum voltage on REG_IN required before FLED_ current regulators are enabled 2.2 2.3 mV mV 2 2.4 FA V TIMERS Flash Duration Timer Range Torch Duration Timer Range TORCH_TMR0 Torch and Flash Duration Timer Accuracy Flash Mode Ramp Rate Settings Torch Mode Ramp Rate Settings Maxim Integrated In 0.256ms steps (Note 5) 0.128 In 0.512ms steps (Note 5) 0.896 2.944 In 1.024ms steps (Note 5) 2.944 11.136 In 2.048ms steps (Note 5) 11.136 43.904 In 4.096ms steps (Note 5) 43.904 437.12 In 8.192ms steps (Note 5) 437.12 699.264 In 131.072ms steps (Note 5) 122.88 561.1 In 262.144ms steps (Note 5) 561.1 1564.67 In 524.288ms steps (Note 5) 1564.67 5767.17 In 1048.576ms steps (Note 5) 5767.17 TA = 0NC to +85NC (Note 4) TA = -40NC to +85NC (Note 4) LED current rampup time (Note 5) 0.896 ms ms 22536.19 -2.5 0 +2.5 -3 0 +3 ms Time it takes for current regulator to ramp from 0mA to full scale current 384 32896 Fs LED current ramp- Time it takes for current regulator to down time. (Note 5) ramp from full scale current to 0mA 384 32896 Fs Time it takes for current regulator to ramp from 0mA to full scale current 16.392 2097 ms LED current ramp- Time it takes for current regulator to down time (Note 5) ramp from full scale current to 0mA 16.392 2097 ms LED current rampup time (Note 5) 11 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS 1 V DIE PROTECTION Shorted LED detection Threshold FLED1, FLED2 Short Debounce timer FLED1, FLED2 From LED short detected until LED current regulator is disabled (Note 5) 1.024 ms OVP_A Debounce Timer Time where adaptive regulation threshold is set at OVP_A threshold until current regulator is disabled (Note 5) 1.024 ms OVP_D Debounce Timer Time where adaptive regulation threshold is set at OVP_D threshold until current regulator is disabled (Note 5) 384 Fs IN_UVLO/THERM Debounce Timer Either time where VIN is less than IN_UVLO threshold or thermal threshold is exceeded until the current regulator is disabled (Note 5) 0.512 ms Thermal Shutdown Hysteresis (Note 4) 20 NC Thermal Shutdown TJ = rising (Note 4) +160 NC NTC THERMAL PROTECTION NTC Bias NTC_BIAS_25C TA = +25NC NTC Bias Temperature Coefficient NTC_T_COMP (Note 4) 0.020 FA/NC NTC Bias On-Time (tNTC_TORCH_ON) Time NTC bias is enabled before temperature measurement is performed in torch mode (Note 5) 0.512 ms NTC Bias On Interval (NTC_TORCH_OFF) Time between enabling of NTC bias in torch mode (Note 5) 131 ms NTC Over Temperature Detection In 50mV steps, NTC falling Threshold Range 194 200 200 NTC Over Temperature Threshold Hysteresis 206 550 50 NTC Over Temperature Threshold For NTC_TH at the 200mV setting Accuracy -2 NTC Short Detection Threshold 55 70 FA mV mV +2 % 120 mV 3.4 V MAXFLASH Low Battery Detect Threshold Range In 33mV steps, VIN falling 2.4 Low Battery Voltage Threshold Accuracy Low Battery Voltage Hysteresis Programmable Range Maxim Integrated % 2.5 In 50mV steps 50 350 mV 12 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators ELECTRICAL CHARACTERISTICS (continued) (VIN = 3.6V, VDD = 1.8V, VPGND_A = VPGND_B = VAGND = 0V, VTX1_MASK = VTX2_MASK = VTORCH_EN = VFLASH_STB = 0V, fSW = 4MHz, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC. See Figure 1.) (Note 3) PARAMETER CONDITIONS Low Battery Inhibit Timer Low Battery Inhibit Time Accuracy MIN TYP MAX Falling in 256Fs steps (Note 5) 256 2048 Rising in 256Fs steps (Note 5) 256 2048 -3 +3 (Note 4) UNITS Fs % Note 3: All devices are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by design. Note 4: Parameter not production tested. Parameter guaranteed by design through characterization. Note 5: Parameter production tested through scan. Parameter guaranteed by design through characterization. Typical Operating Characteristics (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 2.5V, VOUT = 4V, FPWM) 50 40 1MHz SKIP 4MHz FREQUENCY SCALING AND SKIP 2MHz FREQUENCY SCALING AND SKIP 80 1MHz, 1H 70 4MHz, 0.47H 60 50 2MHz, 1H 40 70 40 30 20 20 10 10 10 1 0 0 10 2MHz FREQUENCY SCALING FPWM 50 20 0.1 4MHz FREQUENCY SCALING FPWM 60 30 0.01 MAX77387 toc03 90 30 0 0.001 0.1 0.01 1 0.01 10 0.1 1 10 OUTPUT CURRENT (A) OUTPUT CURRENT (A) OUTPUT CURRENT (A) DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 3.2V, VOUT = 4V) 1H DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 3.2V, VOUT = 4V, FPWM) DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 3.2V, VOUT = 4V) 1H 70 1MHz SKIP 50 2MHz FREQUENCY SCALING SKIP 4MHz FREQUENCY SCALING SKIP 40 80 90 80 4MHz, 0.47H 70 60 1MHz, 1H 50 2MHz, 1H 40 60 50 40 30 30 20 20 20 10 10 10 0.01 0.1 OUTPUT CURRENT (A) Maxim Integrated 1 10 0 2MHz FREQUENCY 4MHz FREQUENCY SCALING FPWM SCALING FPWM 70 30 0 0.001 MAX77387 toc06 90 EFFICIENCY (%) 80 100 MAX77387 toc05 90 60 100 MAX77387 toc04 100 EFFICIENCY (%) 80 EFFICIENCY (%) 70 90 EFFICIENCY (%) EFFICIENCY (%) 80 100 MAX77387 toc02 90 60 100 MAX77387 toc01 100 DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 2.5V, VOUT = 4V) 1H EFFICIENCY (%) DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 2.5V, VOUT = 4V) 1H 0 0.01 0.1 1 OUTPUT CURRENT (A) 10 0.01 0.1 1 10 OUTPUT CURRENT (A) 13 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 3.7V, VOUT = 4V, FPWM) 90 80 2MHz FREQUENCY 4MHz FREQUENCY SCALING SKIP SCALING SKIP 60 50 40 1MHz, 1H 70 2MHz, 1H 60 50 90 80 EFFICIENCY (%) 1MHz SKIP 70 EFFICIENCY (%) 4MHz, 0.47H 40 60 40 30 20 20 20 10 10 10 0 0.1 1 10 0 0.1 0.01 1 10 OUTPUT CURRENT (A) OUTPUT CURRENT (A) DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT, VOUT = 4.5V 4MHz FREQUENCY SCALING AND SKIP 1H DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT, VOUT = 4.5V 2MHz FREQUENCY SCALING AND SKIP 1H 80 EFFICIENCY (%) VIN = 3.7V 70 VIN = 3.2V 60 50 90 80 VIN = 2.5V 40 70 VIN = 3.2V VIN = 3.7V 60 50 100 90 80 VIN = 2.5V 40 50 40 30 20 20 20 10 10 10 0.01 0.1 OUTPUT CURRENT (A) Maxim Integrated 1 10 VIN = 3.2V 60 30 0 0.001 10 VIN = 3.7V 70 30 0 0.001 1 DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VOUT = 4V, 4MHz FPWM, 0.47H) EFFICIENCY (%) 90 0.1 OUTPUT CURRENT (A) 100 MAX77387 toc10 100 0.01 MAX77387 toc12 0.01 4MHz FREQUENCY SCALING FPWM 50 30 0 0.001 2MHz FREQUENCY SCALING FPWM 70 30 MAX77387 toc11 EFFICIENCY (%) 80 100 MAX77387 toc08 90 EFFICIENCY (%) 100 MAX77387 toc07 100 DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 3.7V, VOUT = 4V) 1H MAX77387 toc09 DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VIN = 3.7V, VOUT = 4V) 1H VIN = 2.5V 0 0.01 0.1 OUTPUT CURRENT (A) 1 10 0.01 0.1 1 10 OUTPUT CURRENT (A) 14 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. DC-DC CONVERTER EFFICIENCY vs. LOAD CURRRENT, VOUT = 5V 4MHz FREQUENCY SCALING AND SKIP 1H 70 EFFICIENCY (%) VIN = 3.7V VIN = 3.2V 60 50 40 VIN = 2.5V 70 VIN = 3.2V 60 50 VIN = 2.5V 40 80 40 30 20 20 10 10 10 0.1 1 10 0.01 0.1 1 VIN = 2.5V 50 20 0.01 VIN = 3.2V 60 30 0 0.001 VIN = 3.7V 70 30 0 0 0.001 10 0.01 0.1 1 10 OUTPUT CURRENT (A) OUTPUT CURRENT (A) OUTPUT CURRENT (A) DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT (VOUT = 5V, 4MHz FPWM, 0.47H) DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT, VOUT = 5V 2MHz FPWM 1H DC-DC CONVERTER EFFICIENCY vs. VIN, VOUT = 4.5V, 4MHz FREQUENCY SCALING AND SKIP 1H VIN = 3.2V 60 VIN = 3.7V 50 40 80 EFFICIENCY (%) 70 VIN = 2.5V 100 70 VIN = 3.2V 50 VIN = 2.5V 40 90 80 VIN = 3.7V 60 70 60 50 30 30 20 20 20 10 10 10 0 0 0.1 1 OUTPUT CURRENT (A) Maxim Integrated 10 0.01 0.1 1 OUTPUT CURRENT (A) 10 IOUT = 1A = 100mA = 2A = 10mA = 1mA 40 30 0.01 MAX77387 toc18 80 90 EFFICIENCY (%) 90 MAX77387 toc17 100 MAX77387 toc16 100 EFFICIENCY (%) VIN = 3.7V 90 EFFICIENCY (%) 80 90 80 100 MAX77387 toc14 90 EFFICIENCY (%) 100 MAX77387 toc13 100 DC-DC CONVERTER EFFICIENCY vs. LOAD CURRRENT, VOUT = 5V 2MHz FREQUENCY SCALING AND SKIP 1H MAX77387 toc15 DC-DC CONVERTER EFFICIENCY vs. LOAD CURRENT, VOUT = 4.5V 2MHz FPWM 1H 0 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 15 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. IOUT = 1A = 100mA = 2A = 10mA = 1mA VOUT = 4.5V 40 30 20 10 3.0 3.5 4.0 40 70 60 40 30 20 10 2 LEDS, VF = 3V 400 600 800 VIN = 4.2V 50 20 200 VIN = 3.6V 80 30 0 VIN = 2.5V 90 2 LEDS, VF = 3V 0 1000 0 200 400 600 800 INPUT VOLTAGE (V) LED CURRENT (A) LED CURRENT (A) LED EFFICIENCY vs. LED CURRENT (4MHz, FPWM) LED EFFICIENCY vs. LED CURRENT (2MHz, FPWM) INPUT CURRENT LIMIT vs. TEMPERATURE 50 VIN = 4.2V 40 70 60 50 30 30 20 20 10 2 LEDS, VF = 3V 0 200 400 600 LED CURRENT (A) Maxim Integrated 800 1000 VIN = 4.2V 40 ILIM = 2A 2.0 ILIM = 1.75A 1.8 1.6 ILIM = 1.5A 1.4 ILIM = 1.25A 1.2 10 2 LEDS, VF = 3V 0 0 200 400 600 LED CURRENT (A) 800 1000 1000 2.2 INPUT CURRENT LIMIT (A) 60 VIN = 3.6V 80 EFFICIENCY (%) 70 VIN = 2.5V 90 MAX77387 toc23 VIN = 3.6V 80 100 MAX77387 toc22 VIN = 2.5V 90 0 VIN = 4.2V 0 4.5 100 EFFICIENCY (%) 60 10 0 2.5 70 50 100 MAX77387 toc24 60 50 80 EFFICIENCY (%) 70 VIN = 3.6V EFFICIENCY (%) 80 VIN = 2.5V 90 MAX77387 toc20 90 EFFICIENCY (%) 100 MAX77387 toc19 100 LED EFFICIENCY vs. LED CURRENT (2MHz, FREQUENCY SCALING, SKIP ALLOWED) MAX77387 toc21 LED EFFICIENCY vs. LED CURRENT (4MHz, FREQUENCY SCALING, SKIP ALLOWED) DC-DC CONVERTER EFFICIENCY vs. VIN, 2MHz FREQUENCY SCALING AND SKIP 1H VIN = 3.2V VOUT = 4.5V 1.0 -50 -25 0 25 50 75 100 TEMPERATURE (C) 16 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. SWITCHING FREQUENCY vs. TEMPERATURE (2MHz FPWM) 4.00 3.95 VIN = 2.5V 3.90 2.04 2.02 2.00 1.98 1.96 1.92 1.90 0 25 50 75 VIN = 2.5V 1.94 3.80 -25 MAX77387 toc26 2.06 3.85 -50 VIN = 4.2V VIN = 3.7V VIN = 3.4V VIN = 3.1V 2.08 100 1.050 VIN = 4.2V VIN = 3.7V VIN = 3.4V VIN = 3.1V 1.040 SWITCHING FREQUENCY (MHz) 4.05 1.030 1.020 1.010 1.000 0.990 0.980 VIN = 2.5V 0.970 0.960 0.950 -50 -25 0 25 50 75 100 -50 -25 0 25 50 75 100 TEMPERATURE (C) OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT (VIN = 3.6V VOUT = 5V FPWM) OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT (VIN = 3.6V, VOUT = 5V FPWM) OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT (VIN = 3.6V, VOUT = 5V FPWM) -1 4MHz -2 -3 -4 2MHz 1MHz -5 -6 -7 0 -1 -3 -5 -8 1000 1500 Maxim Integrated 2000 1MHz -6 -9 LOAD CURRENT (mA) 2MHz -4 -7 500 4MHz -2 -8 0 DCDC_GAIN = 1 1 DCDC_GAIN = 1 0 OUTPUT VOLTAGE ACCURACY (%) DCDC_GAIN = 0 0 OUTPUT VOLTAGE ACCURACY (%) 1 -1 4MHz -2 MAX77387 toc29b TEMPERATURE (C) MAX77387 toc29a TEMPERATURE (C) MAX77387 toc28 SWITCHING FREQUENCY (MHz) 4.10 2.10 SWITCHING FREQUENCY (MHz) VIN = 4.2V VIN = 3.7V VIN = 3.4V VIN = 3.1V 4.15 OUTPUT VOLTAGE ACCURACY (%) MAX77387 toc25 4.20 SWITCHING FREQUENCY vs. TEMPERATURE (1MHz FPWM) MAX77387 toc27 SWITCHING FREQUENCY vs. TEMPERATURE (4MHz FPWM) -3 -4 2MHz -5 -6 1MHz -7 -8 -9 -10 0 500 1000 1500 LOAD CURRENT (mA) 2000 0 500 1000 1500 2000 LOAD CURRENT (mA) 17 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. OUTPUT VOLTAGE ACCURACY vs. TEMPERATURE SOFT-START (4MHz, FPWM) MAX77387 toc31 MAX77387 toc30 OUTPUT VOLTAGE ACCURACY (%) 0.5 VIN = 3.6V VIN = 5V 0.4 0.3 2V/div 0.2 0 VOUT 0.1 1A/div 0 200mA /div 0 IIN -0.1 -0.2 -0.3 -0.4 ILED1 -0.5 -50 -25 0 25 50 75 VIN = 2.5V VOUT = 4.5V 0 100 400s/div TEMPERATURE (C) SOFT-START (4MHz, FREQUENCY SCALING, SKIP ALLOWED) LINE TRANSIENT (4MHz, FPWM) MAX77387 toc32 MAX77387 toc33 3.6V/div 2V/div VIN VOUT 1A/div 0 200mA /div IIN 100mV/div AC-COUPLED VOUT ILXA ILXB ILED1 3.1V/div 0 500mA /div 0 IOUT = 500mA VIN = 3.4V VOUT = 4.5V 500mA /div 0 0 400s/div 200s/div LINE TRANSIENT (2MHz, FPWM) LOAD TRANSIENT (500mA-1A-500mA) 4MHz, FREQUENCY SCALING, SKIP ALLOWED MAX77387 toc35 MAX77387 toc34 1A 3.6V/div VIN 3.1V/div 200mV/div AC-COUPLED VOUT ILXA 500mA VOUT 500mV/div AC-COUPLED 500mA /div 0 IOUT = 500mA ILXB 500mA /div 0 200s/div Maxim Integrated IOUT ILXA VIN VIN = 3.6V VOUT = 5V STANDARD GAIN 1A/div 0 2V/div 0 20s/div 18 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. LOAD TRANSIENT (0A-1A-0A) 4MHz, FREQUENCY SCALING, SKIP ALLOWED LOAD TRANSIENT (500mA-1A-500mA) 2MHz FPWM MAX77387 toc36 MAX77387 toc37 1A 1A IOUT 0A VOUT 500mV/div AC-COUPLED ILXA VIN VIN = 3.6V VOUT = 5V DCDC_GAIN = 0 1A/div 2V/div IOUT 500mA VOUT 500mA/div AC-COUPLED ILXA VIN 0 VIN = 3.6V VOUT = 5V DCDC_GAIN = 0 20s/div 20s/div LOAD TRANSIENT (1mA-1A-1mA) 2MHz FPWM LOAD TRANSIENT (1mA-2A-1mA) 2MHz FPWM MAX77387 toc38 1A/div 0 2A/div 0 MAX77387 toc39 1A IOUT 0mA VOUT 500mV/div AC-COUPLED 2A IOUT 0A 1V/div AC-COUPLED VOUT ILXA VIN VIN = 3.6V VOUT = 5V DCDC_GAIN = 0 1A/div 0 2V/div 2A/div ILXA VIN 0V 2V/div ILIM IS CONSTANTLY BEING TRIPPED DCDC_GAIN = 0 20s/div 200s/div LOAD TRANSIENT (1mA-2A-1mA) 4MHz FPWM LOAD TRANSIENT (1mA-2A-1mA) 2MHz FPWM MAX77387 toc41 MAX77387 toc40 IOUT 2A IOUT 2A 0A 0A VOUT 1A /div AC-COUPLED 1V/div AC-COUPLED VOUT ILXA 2A/div 0 2V/div VIN ILIM IS CONSTANTLY BEING TRIPPED DCDC_GAIN = 0 200s/div Maxim Integrated 0V 0V 2A/div 0 ILXA VIN VIN = 3.6V VOUT = 5V DCDC_GAIN = 1 2V/div 0 20s/div 19 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. LIGHT-LOAD SWITCHING WAVEFORMS (4MHz FPWM) LIGHT-LOAD SWITCHING WAVEFORMS (2MHz FPWM) MAX77387 toc42 MAX77387 toc43 VOUT 10mV/div AC-COUPLED VOUT VLXA 2V/div VLXA 20mV/div AC-COUPLED 2V/div 0V ILXB 100mA/div 0A ILXA 0V ILXA 200mA /div 0A ILXB IOUT = 30mA, VOUT = 4.5V, VIN = 3.4V IOUT = 30mA, VOUT = 4.5V, VIN = 3.4V 200ns/div 400ns/div LIGHT-LOAD SWITCHING WAVEFORMS (4MHz, FREQUENCY SCALING, SKIP ALLOWED) MODERATE-LOAD SWITCHING WAVEFORMS (4MHz,FPWM) MAX77387 toc45 MAX77387 toc44 10mV/div AC-COUPLED VOUT VOUT 20mV/div AC-COUPLED VLXA 2V/div VLXA 0 100mA/div ILXA ILXB 0A 0V ILXB ILXA IOUT = 300mA, VOUT = 4.5V, VIN = 3.4V IOUT = 30mA, VOUT = 4.5V, VIN = 3.4V 400ns/div 200ns/div MODERATE-LOAD SWITCHING WAVEFORMS (2MHz,FPWM) HEAVY-LOAD SWITCHING WAVEFORMS (4MHz,FPWM) MAX77387 toc46 MAX77387 toc47 20mV/div AC-COUPLED VOUT 20mV/div AC-COUPLED VOUT VLXA VLXA ILXB ILXA 200mA/div 0A 2V/div 2V/div 0V 0V 500mA/div 0A IOUT = 300mA, VOUT = 4.5V, VIN = 3.4V 400ns/div Maxim Integrated ILXB ILXA 500mA/div IOUT = 1000mA, VOUT = 4.5V, VIN = 3.4V 0A 200ns/div 20 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. HEAVY-LOAD SWITCHING WAVEFORMS (2MHz,FPWM) 1.25A CURRENT LIMIT MAX77387 toc48 MAX77387 toc49 20mV/div AC-COUPLED VOUT 20mV/div AC-COUPLED VOUT ILXB ILXA VLXA 500mA/div VIN = 2.5V, VOUT = 4.5V 2V/div 0V ILXB ILXA 500mA/div IOUT = 1000mA, VOUT = 4.5V, VIN = 3.4V 0A VLXA 2V/div 0A 0V 400ns/div 200ns/div 1.5A CURRENT LIMIT 1.75A CURRENT LIMIT MAX77387 toc50 MAX77387 toc51 20mV/div AC-COUPLED VOUT ILXB ILXA 500mA/div VIN = 3V, VOUT = 5V VLXA 20mV/div AC-COUPLED VOUT ILXB ILXA 500mA/div VIN = 3V, VOUT = 5V 0A 2V/div 0A VLXA 2V/div 0V 0V 200ns/div 200ns/div 2A CURRENT LIMIT LED CURRENT RIPPLE (4MHz, FWPM) MAX77387 toc52 MAX77387 toc53 10mV/div AC-COUPLED VOUT 20mV/div AC-COUPLED VOUT ILXB ILXA 2x IFLED = 100mA VIN = 3.6V 500mA/div VIN = 3V, VOUT = 5V IFLED1 10mA/div IFLED2 10mA/div 0A VLXA 2V/div 0V 200ns/div Maxim Integrated 4s/div 21 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. LED CURRENT RIPPLE (2MHz, FWPM) LED CURRENT RIPPLE (4MHz, FWPM) MAX77387 toc54 MAX77387 toc55 10mV/div AC-COUPLED VOUT 10mV/div AC-COUPLED VOUT 2x IFLED = 100mA VIN = 3.6V 2x IFLED = 500mA VIN = 3.6V IFLED1 10mA/div IFLED1 10mA/div IFLED2 10mA/div IFLED2 10mA/div 2s/div 2s/div LED CURRENT RIPPLE (2MHz, FWPM) LED CURRENT RIPPLE (4MHz, FWPM) MAX77387 toc56 MAX77387 toc57 20mV/div AC-COUPLED VOUT 10mA/div IFLED1 20mV/div AC-COUPLED VOUT 10mA/div IFLED1 2x IFLED = 500mA VIN = 3.6V 2x IFLED = 1000mA VIN = 3.6V IFLED2 10mA/div IFLED2 10mA/div 2s/div 10s/div LED CURRENT RIPPLE (2MHz, FWPM) TORCH ENABLED BY TORCH_EN (ADAPTIVE MODE NO PREBIAS) MAX77387 toc58 MAX77387 toc59 2V/div 50mV/div VOUT VTORCH_EN 0V 100mA /div 0A IFLED1 IFLED1 10mA/div 2x IFLED = 1000mA VIN = 3.6V VOUT IFLED2 10mA/div 2s/div Maxim Integrated 100mA /div 0A IFLED2 4MHz, FPWM 2 x IFLED = 100mA (DAC MODE) 2V/div 0V 2ms/div 22 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. TORCH ENABLED BY TORCH_EN (ADAPTIVE MODE BIASED) TORCH ENABLED BY TORCH_EN (ADAPTIVE MODE NO PREBIAS) MAX77387 toc60 MAX77387 toc61 2V/div 2V/div VTORCH_EN IFLED1 0V 100mA /div 0A IFLED2 100mA /div 0A 100mA /div IFLED2 2V/div 0V 0A IFLED1 VOUT 4MHz, FPWM 2 x IFLED = 100mA (DAC MODE) 100mA /div VTORCH_EN VOUT 0A 4MHz, FPWM 2x IFLED = 125mA (PWM MODE. 25% DUTY CYCLE) 2ms/div 400s/div TORCH ENABLED BY TORCH_EN (ADAPTIVE MODE BIASED) FLASH ENABLED BY FLASH_STB (ADAPTIVE MODE NO PREBIAS) MAX77387 toc62 MAX77387 toc63 2V/div VTORCH_EN 100mA /div 0A IFLED1 2V/div VFLASH_STB 500mA /div 0A IFLED1 100mA /div IFLED2 0A 500mA /div IFLED2 0A 2V/div 2V/div VOUT 4MHz, FPWM 2x IFLED = 125mA (PWM MODE. 25% DUTY CYCLE) VOUT 4MHz, FPWM 2x IFLED = 1A 400s/div 200s/div FLASH ENABLED BY FLASH_STB (ADAPTIVE MODE BIASED) FLASH ENABLED BY FLASH_STB (ADAPTIVE MODE BIASED) MAX77387 toc64 MAX77387 toc65 2V/div 500mV/div VOUT VFLASH_STB 500mA /div IFLED1 2V/div 0A 500mA /div IFLED2 VFLASH_STB 500mA /div 500mA /div 0A VOUT 2V/div 4MHz, FPWM 2x IFLED = 1A IFLED1 0A 4MHz, FPWM 2x IFLED = 1A IFLED2 400s/div Maxim Integrated 2V/div 0A 400s/div 23 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. FLASH RAMP DOWN FLASH RAMP DOWN MAX77387 toc66 MAX77387 toc67 1V/div VOUT 500mA /div IFLED1 IFLED2 IFLED1 500mA /div IFLED2 0A 500mA /div 0A 4MHz, FPWM 2x IFLED = 1A 0A 500mA /div 0A VOUT 2V/div 4MHz, FPWM 2x IFLED = 1A 0A 100s/div 0A 200s/div TX1 MASK (RISING EDGE) TX1 AND TX2 MASKS MAX77387 toc68 MAX77387 toc69 VFLASH_STB VFLASH_STB VTX1_MASK VTX1_MASK VTX2_MASK VTX2_MASK IFLED1 = IFLED2 = 1A TX1 MASK = 500mA TX2 MASK = OFF IFLED1 = IFLED2 = 1A TX1 MASK = 0A TX2 MASK = 500mA 500mA /div IFLED1 IFLED2 0A 500mA /div IFLED1 IFLED2 100ms/div 0A 100ms/div TX1 AND TX2 MASKS MAXFLASH MAX77387 toc70 MAX77387 toc71 100mA /div VFLASH_STB IFLED1 VTX1_MASK VTX2_MASK 0A 100mA /div IFLED1 = IFLED2 = 1A TX1 MASK = 0A TX2 MASK = 500mA IFLED2 VOUT 350mV HYSTERESIS 3.39V THRESHOLD 1024s INPUT TIMER 0A 200mV/div AC-COUPLED 500mA /div IFLED1 IFLED2 0A 100ms/div Maxim Integrated VIN = 3.55V VOUT = 5V IFLED1 = IFLED2 = 1A 10ms/div 24 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. LED FLASH CURRENT ACCURACY vs. LOAD CURRENT FLASH CURRENT ACCURACY vs. TEMPERATURE ILED2 2 0 -2 ILED1 200 400 600 800 0 -0.5 VIN = 3.6 VIN = 5V ILED = 500mA -1.5 -50 0 25 50 75 LED TORCH CURRENT ACCURACY vs. LOAD CURRENT (PWM MODE) 10 8 6 ILED2 4 2 VIN = 3.6V ILED1 50 6 100 150 200 ILED2 5 4 3 ILED1 2 1 0 -1 -2 VIN =3.6V -3 250 0 TORCH CURRENT ACCURACY vs. TEMPERATURE (DAC MODE) 100 150 200 250 SHUTDOWN CURRENT vs. TEMPERATURE 5.0 MAX77387 toc76 VIN = 3.6V VOUT = 5V ILED = 125mA 4.0 3.0 2.0 VIN = 3.6V 4.5 4.0 SUPPLY CURRENT (A) 5.0 50 LED FLASH CURRENT SETTING (mA) LED FLASH CURRENT SETTING (mA) 6.0 100 MAX77387 toc75 LED TORCH CURRENT ACCURACY vs. LOAD CURRENT (DAC MODE) 0 TORCH CURRENT ACCURACY (%) -25 TEMPERATURE (C) MAX77387 toc74 LED TORCH CURRENT ACCURACY (%) 0.5 LED FLASH CURRENT SETTING (mA) 12 0 1.0 1000 LED TORCH CURRENT ACCURACY (%) 0 1.5 -1.0 VIN = 3.6V -4 2.0 MAX77387 toc77 4 MAX77387 toc73 6 2.5 FLASH CURRENT ACCURACY (%) MAX77387 toc72 LED FLASH CURRENT ACCURACY (%) 8 3.5 3.0 2.5 2.0 1.5 1.0 1.0 0.5 0 0 -50 -25 0 25 50 TEMPERATURE (C) Maxim Integrated 75 100 -50 -25 0 25 50 75 100 TEMPERATURE (C) 25 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 3.6V, TA = +25NC, unless otherwise noted. SUPPLY CURRENT vs. INPUT VOLTAGE (4MHz, FREQUENCY SCALING, SKIP ALLOWED) SHUTDOWN CURRENT vs. INPUT VOLTAGE MAX77387 toc79 1000 SUPPLY CURRENT (A) 60 SUPPLY CURRENT (A) 1200 MAX77387 toc78 70 50 40 30 20 800 600 400 200 10 0 0 2.5 3.0 3.5 4.0 4.5 5.0 2.5 5.5 3.0 INPUT VOLTAGE (V) SUPPLY CURRENT vs. INPUT VOLTAGE (4MHz FPWM WITH FREQUENCY SCALING) SUPPLY CURRENT (mA) 4MHz FPWM 15 10 4MHz FPWM WITH FREQUENCY SCALING 500 495 490 485 480 475 VIN = 3.2V VOUT = 4.5V 470 465 0 2.5 3.0 3.5 5.5 505 20 05 5.0 MAX77387 toc81 25 4.5 510 SUPPLY CURRENT (A) VOUT = 4.5V 4.0 SUPPLY CURRENT vs. TEMPERATURE (4MHz, FREQUENCY SCALING, SKIP ALLOWED) MAX77387 toc80 30 3.5 INPUT VOLTAGE (V) 4.0 -50 4.5 -25 0 25 50 75 100 TEMPERATURE (C) INPUT VOLTAGE (V) 30 MAX77387 toc82 SUPPLY CURRENT vs. TEMPERATURE (2MHz FPWM, 4MHz FPWM) 2MHz FPWM SUPPLY CURRENT (mA) 25 20 4MHz FPWM 15 10 5 VIN = 3.2V VOUT = 4.5V 0 -50 -25 0 25 50 75 100 TEMPERATURE (C) Maxim Integrated 26 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Bump Configuration TOP VIEW (BUMP SIDE DOWN) + MAX77387 1 2 3 4 5 LX_A PGND_A TORCH_EN PGND_B LX_B A OUT_A TX1_MASK TX2_MASK FLASH_STB OUT_B B VDD SCL REG_IN NTC IN SDA FLED1 REG_IN FLED2 AGND C D WLP Bump Description PIN NAME FUNCTION A1 LX_A Inductor Connection for Phase A. Connect LX_A to the switched side of the inductor and to the phase A synchronous rectifier. LX_A is internally connected to the drain of the internal low-side MOSFET. A2 PGND_A A3 TORCH_EN A4 PGND_B A5 LX_B Maxim Integrated Power Ground for DC-DC Converter Phase A. Connect to PGND (A2 and A4 together) as close as possible to the IC. Make a star connection between input and output capacitors to ensure a short ground loop. Connect to the common ground plane of the application. Logic Input. Used to enable torch/flash mode (I2C programmable). TORCH_EN input has an optional 800kI pulldown resistor to AGND. Power Ground for DC-DC Converter Phase B. Connect to PGND (A2 and A4 together) as close as possible to the IC. Make a star connection between input and output capacitors to ensure a short ground loop. Connect to the common ground plane of the application. Inductor Connection for Phase B. Connect LX_B to the switched side of the inductor and to the phase B synchronous rectifier. LX_B is internally connected to the drain of the internal low-side MOSFET. 27 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Pin Description (continued) PIN NAME FUNCTION DC-DC Step-Up Converter Output Voltage for Phase A. Bypass this output using a ceramic capacitor. See the Output Capacitor Selection section. Ensure that (B1) is directly connected to the output capacitor and not to the REG_IN bumps (C3 or D3). This ensures lowest output ripple current of the FLED current regulators. During shutdown OUT_A is high impedance. B1 OUT_A B2 TX1_MASK Logic Input. TX1_MASK input has an optional 800kI pulldown resistor to AGND. B3 TX2_MASK Logic Input. TX2_MASK input has an optional 800kI pulldown resistor to AGND. B4 FLASH_STB Logic Input. Used to enable flash/torch mode (I2C programmable). FLASH_STB input has an optional 800kI pulldown resistor to AGND. DC-DC Step-Up Converter Output Voltage for Phase B. Bypass this output using a ceramic capacitor. See the Output Capacitor Selection section. Ensure that (B5) is directly connected to the output capacitor and not to the REG_IN bumps (C3 or D3). This ensures the lowest output ripple current of the FLED current regulators. During shutdown OUT_B is high impedance. B5 OUT_B C1 VDD Voltage for SDA/SCL Logic Levels. The I2C registers are reset when VDD is low. C2 SCL I2C Clock Input. Data is read on the rising edge of SCL. C3, D3 REG_IN Input Supply for Current Regulators. Connect directly to the output capacitors. Make sure not to share the trace between OUT_ and the capacitor since this results in increased output ripple current on the LED output. C4 NTC NTC Bias Output. NTC provides 200FA to bias the NTC thermistor. The NTC voltage is compared to the trip threshold programmed by the NTC_CNTL register. NTC is high impedance during shutdown. Connect NTC to IN if not used. C5 IN D1 SDA Input supply. Connect input bypass capacitor close to this input and AGND. This input is used for low noise supply for internal bias as well as for the MAXFLASH function. I2C Data Input. Data is read on the rising edge of SCL and data is clocked out on the falling edge of SCL. FLED1 Flash LED1. High-side current regulator output. Current flowing out of FLED1 is based on I2C register settings. Connect FLED1 to the anode of a flash LED or LED module. Optionally connect FLED1 and FLED2 together for driving a single LED module. Connect FLED1 to REG_IN if not used. FLED1 is high impedance during shutdown. D4 FLED2 Flash LED2. High-side current regulator output. Current flowing out of FLED2 is based on I2C register settings. Connect FLED2 to the anode of a flash LED or LED module. Optionally connect FLED1 and FLED2 together for driving a single LED module. Connect FLED2 to REG_IN if not used. FLED2 is high impedance during shutdown. D5 AGND Analog Ground. Connect to common ground plane of the application. D2 Maxim Integrated 28 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators PEAK INPUT CURRENT LIMIT PGND_A PWM COMP SLOPE AND RAMP COMPENSATION PWM LOGIC MAX77387 0.47F OUT_A LX_A 10F 10V 0402 REVERSE BLOCKING 0.47F REVERSE BLOCKING LX_B OUT_B PWM COMP 10F 10V 0402 10F 10V 0402 SLOPE AND RAMP COMPENSATION PWM LOGIC PGND_B PEAK INPUT CURRENT LIMIT IN ERROR AMP UVLO AND MAXFLASH DCDC SOFT-START AGND DAC 0.1F 6.3V 0201 VDD SDA SCL FREQUENCY SCALING ADAPTIVE OUTPUT CONTROL I2C INTERFACE REG_IN REG_IN TX1_MASK TX2_MASK TORCH_EN REGISTERS SELECT MIN FLED1 LOGIC INTERFACE FLASH_STB NTC FLED2 Figure 1. Detailed Block Diagram and Typical Application Circuit Maxim Integrated 29 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Detailed Description The MAX77387 flash driver IC integrates a dual-phase 2.0A adaptive PWM step-up DC-DC converter and two high-side 1A current regulators for LED camera flash and torch applications. All aspects of the device for torch and flash can be controlled through an I2C interface. The input voltage must also be above IN_UVLO for the transition from standby to active mode to occur. If the IN is below the IN_UVLO, the IC remains in standby mode. Active Mode In active mode, the DC-DC converter is enabled and operating in the boost mode set by the DCDC_MODE bits. The current regulators are disabled. Modes of Operation While in active mode, if either current regulator is enabled, then the IC enters torch or flash mode. Shutdown Mode In shutdown mode, only the VDD input is active. Torch Mode In torch mode, the current regulator is enabled according to the torch settings. The IC has five modes of operation. See Figure 2. The IC enters shutdown mode when VDD is reduced below the VDD_UVLO. When the IC enters shutdown mode, all I2C registers are reset. If VDD increases above the VDD_UVLO threshold, the IC exits shutdown mode and enters standby mode. Standby Mode In standby mode, the I2C interface is active and trigger inputs are also active if defined by I2C register (TORCH_ EN and FLASH_STB). The IC continues to operate in torch mode when the torch current regulator is enabled and the flash current regulator is not enabled. If flash mode is enabled for a current regulator, that regulator mode enters flash mode since flash mode has a higher priority. If the current regulator is disabled, then the IC returns to active mode. The IC enters standby mode from active mode when the DC-DC converter is disabled or in the case where the input voltage is below the IN_UVLO. Flash Mode In flash mode, the current regulator is enabled according to the flash settings. If the current regulators are enabled (torch or flash mode) or the DC-DC converter is enabled (in either normal mode, dropout mode), then the IC enters active mode. Once the flash event ends, the IC can either enter torch mode or active mode depending on the torch settings. FLASH MODE DISABLED AND TORCH MODE ENABLED FLASH MODE IN > IN_UVLO OR (DCDC_MODE 00 OR LED CURRENT REGULATOR ENABLED) VDD = IN_UVLO SHUTDOWN STANDBY VDD = LOW IN < UVLO AND (DCDC_MODE = 00 AND LED CURRENT REGULATOR DISABLED) FLASH MODE ENABLED FLASH MODE ENABLED AND TORCH MODE ENABLED FLASH MODE DISABLED TORCH MODE ENABLED ACTIVE TORCH MODE DISABLED TORCH MODE P IN_UVLO Figure 2. Modes of Operation Maxim Integrated 30 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Adaptive Output Voltage Regulation The IC uses an adaptive voltage scheme to optimize system efficiency based on the forward voltage of the populated LED. To ensure that the DC-DC converter is operating in a stable condition and that the current regulators are providing the correct output current levels, the voltages across the current regulators are sampled to determine whether the output voltage of the DC-DC converter needs to be increased or decreased. The adaptive control loop controls an internal 9-bit DAC that sets the output voltage of the DC-DC converter. During a torch or flash event, the DC-DC converter continuously adapts its output voltage up or down by one DAC LSB (VADPT_REG_STEP) every 1Fs during softstart, and every 8Fs during normal operation. During the torch or flash event, the DC-DC converter output voltage is logged and then stored in both the DCDC_OUT and DCDC_OUT_MAX registers. The DCDC_OUT register is used to store the value of the DC-DC converter output voltage just before the current regulator is disabled. The DCDC_OUT_MAX register is used to store the maximum value of the DC-DC converter output voltage that occurred during the torch or flash event. The information stored in these two registers allows the user to predict the forward voltage of the LED for diagnostics. In certain cases, the adaptive control loop operation is limited. During minimum duty cycle operation, the DC-DC converter output voltage is only allowed to increase to ensure correct operation. During the time when the DC-DC converter is operating at the peak input current limit, the DC-DC converter output voltage is only allowed to decrease since increasing the output voltage would require a greater input current than is allowed. If the adaptive control loop attempts to increase the DC-DC converter output voltage above the OVP_D voltage level, then the output voltage is maintained at this level for the duration of the OVP_D debounce time. If the adaptive control loop continues to attempt to increase the output voltage above the OVP_D voltage level after the OVP_D debounce timer expires, then this is an indication that the LED forward voltage is too high for the IC or the LED is not correctly installed. Current Regulator Voltage Headroom The current regulator headroom is selectable between +120mV to +210mV in 30mV steps. This allows the user to optimize for either efficiency or accuracy. Maxim Integrated Lowering the voltage headroom of the current regulator reduces the accuracy and the PSRR of the current regulator while improving the system efficiency. Increasing the voltage headroom of the current regulator improves the accuracy and the PSRR of the current regulator while reducing the system efficiency. Step-Up Converter The IC includes a dual-phase PWM step-up converter that supplies power to the flash LEDs. The output voltage can be adaptively controlled based on the forward voltage of the installed LEDs. The step-up converter switches an internal power MOSFET at frequencies up to 4MHz (per phase), resulting in a maximum output ripple frequency of 8MHz, with a duty cycle that can vary from 3.125% to 75% to maintain constant output voltage as VIN and load vary. Internal circuitry prevents any unwanted subharmonic switching by forcing a minimum dutycycle. Alternatively, the converter can be programmed to enter skip mode for light load conditions to ensure high efficiency for low output current operation. Dual-Phase Operation The advantage of the IC dual-phase control architecture is that the effective switching frequency is doubled. This provides a significant reduction in the output voltage ripple, hence reducing stress on the output capacitor. Lowering the output voltage ripple also lowers the output current ripple of the current regulator, resulting in lower EMI for the system. For high-current applications such as LED flash, the dual phase scheme also helps reduce the inductor size. For example, a traditional single-phase architecture requiring an input current of 3A and an inductor saturation current of 3A would require and inductor sized approximately 5mm x 5mm with a height of 1mm. By going to a dualphase architecture the 5x5mm inductor can be replaced by two 1.8mm x 1.0mm inductors to significantly reduce the total solution size. In addition, the second advantage is inductor saturation current (per phase) could be lowered to 1.8A. Skip Mode In PWM operation, the DC-DC converter switches cycles continuously. When SKIP mode is enabled, the DC-DC converter can disable a switching cycle if the output voltage is sufficiently high. When this condition is detected, the next switching cycle is skipped. The peak inductor current value is chosen to be high enough so that sufficient energy is transferred to the output in a burst of 31 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators switching-cycles that occur less frequently to improve the overall efficiency. However, the output voltage ripple in this mode increases. Noise-sensitive applications that cannot tolerate the increased output voltage ripple can disable skip mode to force continuous PWM operation. See the DCDC_CNTL2 register. Current Sharing For multiphase converters one of the critical parameters is current sharing. If good balance between the phases is not ensured, then one phase could potentially be forced to handle a disproportionate amount of the total output current, resulting in overheating and loss of efficiency. The IC uses a common peak current mode control scheme that inherently provides current balancing between the phases. Switching Frequency Selection The DC-DC converter can be programmed to operate at several different fixed switching frequencies. Alternatively, the DC-DC converter can be programmed to automatically select the optimal switching frequency based on the operating duty cycle. Optimized frequency selection allows the DC-DC converter to operate at the highest available switching frequency for the lowest required duty cycle. See the DCDC_CNTL2 register. Overvoltage Protection The IC provides two overvoltage protection mechanisms. The primary protection mechanism (OVP_D), which is part of the adaptive regulation control, limits the DCDC converter output voltage to the OVP_D threshold for a time duration of tOVP_D before the DC-DC converter and current regulators are disabled. A secondary protection mechanism (OVP_A) limits the DC-DC converter output voltage to the OVP_A threshold that is set higher than the OVP_D threshold, but has a much reduced time duration. If the DC-DC converter output voltage rises above the OVP_A threshold, the DC-DC converter and current regulators are disabled with minimum time delay. True Shutdown When the IC is in standby mode, the DC-DC converter is disabled where both the high side and low side switches are turned off. In addition, the high-side switch's rectifier is reversed biased putting the DC-DC converter output into a high-impedance state, allowing the output to discharge to ground. Maxim Integrated Soft-Start When the input supply is initially applied to the IC, the output is in true shutdown mode, meaning that the output DC-DC converter remains at high impedance. Upon entering active mode the following steps are implemented to ensure a controlled soft-starting of the DC-DC converter output. The soft-start steps are: 1) Precharge When entering precharge, the output voltage is unknown since it was in high impedance. If the highside switch is simply forced on, this can result in a large inrush of current. To avoid this, the high-side switch switches at a 25% duty cycle resulting in a controlled precharge of the output. The precharge is completed once the output voltage reaches VIN - 300mV. If the load on the output exceeds 10mA while precharging, the DC-DC converter remains in precharge mode and the output is unable to reach VIN - 300mV. 2) Ramping of the output voltage In this mode, the output is ramped to DCDC_SS level. The output is ramped at a rate of 1LSB per 1Fs, resulting in 6.25mV/Fs ramp rate. For DCDC_MODE = 00 (low-power adaptive mode), the output does not soft-start before the trigger event. When a torch or flash event is triggered the DC-DC converter first performs step 1, followed by step 2. After the DC-DC converter output is ramped to the DCDC_SS level, the current regulator is then ramped according to the programmed ramp values. For DCDC_MODE = 01 (prebiased adaptive mode), when setting this mode, the DC-DC converter first performs step 1, followed by step 2. Once step 2 is completed the DC-DC converter continues to regulate the output at DCDC_SS level. Once a torch or flash event is triggered, the current regulator is enabled with minimum delay since the output is already precharged. The output current ramps according to the programmed ramp values. Once the current regulator is disabled the output continues to regulate at the DCDC_OUT level. Upon a new torch or flash event the output continues from this DCDC_OUT level. For DCDC_MODE = 10 (fixed voltage mode), when setting this mode, the DC-DC converter first performs step 1, followed by step 2. Once step 2 is completed the DC-DC converter continues to regulate the output at the DCDC_SS level, regardless of status of torch and flash modes. 32 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators TRIGGER EVENT TRIGGER EVENT ILX VOUT DCDC_SS VIN IFLED tDCDC_SS RAMP-UP TIME RAMP-DOWN TIME tBIAS_RDY STEP 1 STEP 3 tOUT_PCHG STEP 2 tTORCH_EN_STDBY Figure 3. DC-DC Converter Soft-Start for DCDC_MODE = 00 DCDC_MODE = 01 MODE = STANDBY MODE = ACTIVE ILX VOUT DCDC_SS IFLED tBIAS_RDY tSTDBY2ACTIVE tOUT_PCHG RAMP-UP TIME RAMP-DOWN TIME tDCDC_SS tTORCH_EN_ACTIV OR tFLASH_EN_ACTIV Figure 4. DC-DC Converter Soft-Start for DCDC_MODE = 01 Maxim Integrated 33 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators DCDC_MODE = 11 MODE = STANDBY MODE = ACTIVE ILX VOUT DCDC_SS IFLED tBIAS_RDY tSTDBY2ACTIVE tOUT_PCHG tDCDC_SS Figure 5 DC-DC Converter Soft-Start for DCDC_MODE = 10 DCDC_MODE = 10 MODE = STANDBY MODE = ACTIVE ILX VOUT VIN IFLED tBIAS_RDY tSTDBY2ACTIVE tOUT_PCHG Figure 6. DC-DC Converter Soft-Start for DCDC_MODE = 11 Maxim Integrated 34 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators For DCDC_MODE = 11 (dropout mode), when setting this mode, the DC-DC converter first performs step 1, after which, the high-side switch is turned on 100%, regardless of the status of torch and flash modes. The time it takes from triggering torch or flash mode until the current is at final value depends on the following conditions: U If the time spent in standby mode is shorter than the internal bias, tBIAS_RDY, then the bias needs to come up before anything happens. U The time duration of the soft-start is dependent on the input voltage and initial charge of the output capacitor, tOUT_PCHG. U The higher the programmed voltage level results in a longer start time (tDCDC_SS). The output is ramped at a rate of 1LSB per 1Fs, resulting in a 6.25mV/Fs ramp rate. U The regulator output current is ramped according to the programmed ramp rate in flash or torch mode. Therefore, the final value of the output current impacts the time duration it takes to ramp the current from 0mA to the final value. End of Trigger Event When the DC-DC converter is disabled, the setting of the DCDC_MODE determines the method to discharge the output. The discharge steps are: 1) The DC-DC converter continues switching the highside switch at 25% duty cycle allowing for the output to be a controlled discharge. During this step, the energy in the output capacitor is gradually transferred from the output capacitor back to the input capacitor, ensuring that the energy is conserved. Step 1 is completed once the output voltage reaches VIN + 200mV. The following describes the end of trigger event when coming from the different modes 01, 10, or 11 to 00. Coming from DCDC_MODE = 01 or 10 to 00, the DC-DC converter goes through all three steps listed above. This ensures that the output is discharged to within VIN + 150mV. Coming from DCDC_MODE = 11 to 00, the DC-DC converter enters true shutdown mode since the output is equal or lower than the input voltage. Gain Selection The gain of the error amplifier of the DC-DC converter determines the load regulation performance as well as setting the minimum output capacitor value required for stable regulation. Lowering the gain results in larger load regulation and a decreased output capacitor value requirement. The following DCDC_GAIN settings are available: U DCDC_GAIN = 0 sets the lowest gain. U DCDC_GAIN = 1 sets the highest gain. For output capacitor values, see the Output Capacitor Selection section. Low-Side Current Limit The IC provides a programmable current limit for the low-side switch. This current limit functions as an input current limit, and is critical for the application since this is the function that determines the maximum current that can be drawn from the input supply. The low side current limit is also important for the choice of inductor since this determines the minimum saturation current. 3) The DC-DC converter transitions from operating in dropout mode to true shutdown mode. In true shutdown mode, the output is high impedance. If the input current limit is reached during operation, the low-side switch terminates the cycle and turns on the high-side switch. When minimum tON condition is reached the duty cycle is limited and the LX peak current might exceed the current limit setting slightly. This results in a drop of the output voltage. The DC-DC converter can operate in continuous input current limit condition. However, due to the drop in output voltage the current regulator parameters cannot be guaranteed in this mode of operation. For DCDC_MODE = 00, the DCDC converter goes through all three steps listed above. This ensures that the output is discharged to within VIN +150mV. The IC has two high-side regulators that can be used for torch and flash modes with the settings: 2) The DC-DC converter high-side switch goes from 25% switching to 100% (dropout mode). This allows the output to be discharged to within VIN + 150mV. For DCDC_MODE = 01, 10, or 11, the DC-DC converter is not disabled therefore the output is not discharged. To disable the DC-DC converter, set DCDC_MODE = 00. Maxim Integrated Current Regulator LED U Flash mode from 15.625mA to 2000mA (1000mA for each current regulator) in 15.625mA steps total 35 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators U Torch mode with DAC mode enabled from 3.91mA to 500mA (250mA for each current regulator) in 3.91mA steps total U Torch mode with PWM mode enabled from 125mA to 1000mA in 125mA steps for PWM dimming with programmable duty cycle from 3.125% to 25% in 3.125% steps. The regulator sources current out of the FLED output, and is always powered from REG_IN. If both torch and flash are enabled for LED current regulator, flash mode always has the highest priority. Each current setting is controlled by I2C interface. For applications requiring higher output current, the two current regulators can be connected in parallel, doubling the output current capability. The total current flowing though the LED is the sum of the programmed FLED1 and FLED2 current. The ramp rate is doubled compared to the dual LED application. If one of the LED current levels is set higher than the other the ramp rate, decrease to 1x as soon as the lower LED current regulator has completed its ramp function. It is therefore recommended that the current settings for FLED1 and FLED2 are set to the same rate of maximum of 1LSB in difference. It is not recommended to use PWM dimming when FLED1 and FLED2 are connected since the LED current regulators are not synchronized together. When FLED1 and FLED2 are connected together, the adaptive control monitors the voltage headroom for each of the current regulators. Since the two FLED pins are connected together, the required output voltage of the FLED1/FLED2 is the same. The adaptive control scheme regulates the voltage across the current regulator to be the preset value. In this case, the required VOUT for FLED1 and FLED2 are the same. DAC and PWM Dimming Dimming control of the current regulators can be achieved using DAC control, PWM control or a combination of both. DAC Control When DAC control is used, the current regulators are set to a constant preprogrammed value. PWM Control When PWM control is used, the current regulators are enabled/disabled at a predetermined frequency, FREQ_PWM[1:0]. The ratio between the on and off times determines the percentage of full-scale current that each current regulator outputs. Using PWM dimming with high frequency and low duty cycle increases the output error due to rise and fall time and becomes a significant part of the total on time. It is therefore not recommended to operate at high frequency and low duty cycle. DAC and PWM Control DAC and PWM control can be used at the same time. For example, in torch mode the full-scale current can be set with the DAC, and then PWM control used to establish a much lower average current. Typically, this is done to eliminate the color shift seen when using a high-current LED at a low DC current setting. REG_IN REG_IN REG_IN REG_IN FLED1 FLED1 FLED2 MAX77387 Figure 7. Driving Two LED Configuration Maxim Integrated FLED2 MAX77387 Figure 8. Driving a Single LED Configuration 36 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Ramp Control Each current regulator has a ramp function that is engaged every time the current regulator is enabled/ disabled or the output current level is changed. This is done to control the EMI of the current regulator output. The ramping of the current regulator is done by ramping one LSB step of the current regulator per the internal clock, providing a staircase ramp of the output current. For flash mode, the output current increases in 15.625mA steps from 15.625mA until the final value. ITORCH_DAC_MAX is the maximum programmable DAC mode torch current (250mA). For torch mode in PWM mode: t TORCH_PWM_UP = TORCH_RU (ITORCH_PWM) ITORCH_PWM_MAX t TORCH__PWM_DOWN = TORCH_RD (ITORCH_PWM) ITORCH_PWM_MAX For torch mode the output current increases in 3.91mA steps from 3.91mA until final value. where: The actual time used for ramping up and down are determined by the following equations. TORCH_RD is the total ramp-down time. For flash mode: t FLASH_UP = FLASH_RU (IFLASH) IFLASH_MAX TORCH_RU is the total ramp-up time. ITORCH_PWM is the programmed PWM mode torch current. ITORCH_PWM_MAX is the maximum programmable PWM mode torch current (1000mA). Torch and Flash Safety Timer FLASH_RD t FLASH_DOWN = (IFLASH) IFLASH_MAX where: FLASH_RU is the total ramp-up time. FLASH_RD is the total ramp-down time. IFLASH is the programmed flash current. IFLASH_MAX is the maximum programmable flash current (1000mA). For torch mode in DAC mode: TORCH_RU t TORCH_DAC_UP = (ITORCH_DAC) ITORCH_DAC_MAX t TORCH_DAC_DOWN = TORCH_RD (ITORCH_DAC) ITORCH_DAC_MAX where: TORCH_RU is the total ramp-up time. TORCH_RD is the total ramp-down time. ITORCH_DAC is the programmed DAC mode torch current. Maxim Integrated The torch/flash safety timers are activated any time torch/ flash mode is respectively enabled. The torch safety timer, programmable from 122.9ms to 22s through I2C, limits the duration of the torch mode in case the torch mode is not disabled through logic control or I2C within the programmed torch safety timer duration. The flash safety timer, programmable from 0.256msec to 699.392ms through I2C, limits the duration of the flash mode in case the flash is not disabled through logic control or I2C within the programmed flash safety timer duration. The flash mode timers operate in either one-shot time mode or maximum duration timer mode or PWM timer mode. The torch mode timers operate only in one-shot time mode. There is a torch mode register setting to disable the timer potentially allowing for indefinite torch mode duration. See Figure 11. See the TORCH_TMR_CNTL[7] register. In maximum flash mode, the trigger input is level triggered, and the timer is only ensuring that the maximum duration of the flash is limited to the preprogrammed threshold. Time duration includes current ramp-up time, but not ramp down time. 37 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators A. MAXIMUM FLASH TIMER MODE OUTPUT CURRENT ENABLING OF FLASH MODE MAXIMUM FLASH SAFETY TIMER MAXIMUM FLASH TIMER B. DISABLED TORCH TIMER MODE OUTPUT CURRENT ENABLING OF TORCH MODE DISABLED SAFETY TIMER Figure 9. Maximum Flash Timer Mode/Disabled Torch Timer Mode Figure 10 OUTPUT CURRENT ENABLING OF TORCH MODE ONE SHOT TORCH/ FLASH TIMER ONE SHOT TORCH/FLASH TIMER Figure 10. One-Shot Torch/Flash Timer Mode Maxim Integrated 38 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators MAXFLASH Function During high load currents on a battery cell, the battery voltage momentarily drops due to internal ESR of the battery in series with impedance between the battery and the load. For equipment requiring a minimum voltage for stable operation, the ESR of the battery needs to be calculated to estimate the maximum current that can be drawn from the battery without making the cell voltage drop below this critical minimum system voltage level. If the system is not able to accurately predict the true ESR and impedance of the system, the minimum operational battery voltage has to be increased to guard band for tolerances and operating conditions. In addition, a smartphone includes multiple applications that are operating asynchronously with the camera flash application. Therefore, it is difficult to predict the load current on the battery at any given time that would require additional guard banding of the battery voltage to insure that a sufficient system voltage is provided during worst case conditions. The MAXFLASH 2.0 function eliminates the requirement for predicting the battery voltage during flash events. The MAXFLASH 2.0 monitors the input voltage while comparing it against a user defined voltage threshold. If the input voltage drops below this user defined threshold, referred to as MAXFLASH_TH, the current regulator output current is reduced by one step. After a given time, referred to as LB_TMR_F, the input voltage is compared against the MAXFLASH_TH threshold again. If the input voltage is still below the MAXFLASH_TH threshold, the current regulator output current is once again reduced by one step to ensure that the minimum operational voltage is available for the rest of the system. However, if the input voltage is near the MAXFLASH_TH threshold plus a user defined hysteresis, referred to as MAXFLASH_HYS, the current regulator output current is increased by one step, but only if the current regulator output current is less than the user defined output current setting. In Maxim Integrated the event that MAXFLASH_HYS is set to 000, the flash current can only be reduced as a result of a low system battery voltage regardless of whether or not the system voltage recovers. This continues for the entire duration of the flash/torch event, ensuring that the current regulator output current is always maximized for the specific operational conditions. If the MAXFLASH 2.0 function is triggered during a torch or flash event, the MAXFLASH bit in the STATUS2 register is set. In the case of a MAXFLASH event, the MAX77387 logs the lowest current setting reached for each current regulator during the torch or flash event. This information is stored in both the MAXFLASH3 and MAXFLASH4 registers. This information can be used to determine whether the reduction in LED light has been sufficient or if the picture quality has been compromised. TX_MASK In the typical application there are several other applications that can draw large peak currents from the battery that are also supplying the flash driver. Since the current from the battery has to be limited to protect the battery from getting damaged, the IC has two logic inputs that can be used to limit the flash current during high current events, such as GSM Tx or WCDMA Tx. The TX1_MASK and TX2_MASK can be used to limit the maximum current for the LED by setting the maximum allowed flash current during Tx event. If TX1_MASK and TX2_MASK are triggered at the same time, the current is limited by the TX1_MASK. Once the TX1_MASK event is no longer present, output current is limited by TX2_MASK if this event is still valid. Once a TX_MASK event is triggered the output current is reduced within the tTX_MASK_EN to ensure that the current draw from the battery does not exceed the maximum allowed for the battery. Once the TX_MASK event is no longer present the output current is ramped from the reduced value to normal flash current level according to the ramp up for flash mode. 39 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Figure 11 tFLASH_UP = FLASH_RU (IFLED-(FLASH_TX1_MASK OR FLASH_TX2_MASK)) 256 tTX_MASK_EN IFLED1 IFLED2 FLASH1[6:0] FLASH2[6:0] FLASH_TX1_MASK[5:0] OR FLASH_TX2_MASK[5:0] TX1_MASK OR TX2_MASK Figure 11. TX1_MASK or TX2_MASK During Flash Mode Figure 12 tFLASH_UP = tTX_MASK_EN IFLED1 IFLED2 FLASH1[6:0] FLASH2[6:0] FLASH_TX1_MASK[5:0] FLASH_RU (IFLED-(FLASH_TX1_MASK-FLASH_TX2_MASK)) 256 tFLASH_UP = FLASH_RU (FLASH_TX2_MASK)) 256 FLASH_TX2_MASK[5:0] TX1_MASK TX2_MASK Figure 12. TX1_MASK and TX2_MASK Occurring at Same Time NTC Control An NTC input is provided for the (optional) finger-burn protection feature. To use this feature, connect a negative temperature thermistor (NTC) between NTC and AGND. In flash mode, the IC sources 200FA current out of the NTC pin, and the voltage established by this current and the NTC resistance is compared internally to a voltage threshold in the range of 200mV to 550mV, programmed through bits NTC_TH_FLASH[2:0]. If the voltage on the NTC pin falls below the programmed threshold during a flash event, the flash cycle is immediately terminated, and an indication is latched into the Status 2 register. To disable this function, clear NTC_EN bit in the NTC Control registers. Maxim Integrated In torch mode, the IC pulses a 200FA current out of the NTC pin, and the voltage established by this current and the NTC resistance is compared internally to a voltage threshold in the range of 200mV to 550mV, programmed through bits NTC_TH_TORCH[2:0]. If the voltage on the NTC pin falls below the programmed threshold during a torch event, the torch cycle is immediately terminated, and an indication is latched into the Status 2 register. To disable this function, clear NTC_EN bit in the NTC Control registers. The NTC pulse time is defined by tNTC_TORCH_ON and tNTC_TORCH_OFF. The NTC biased current is pulsed in torch mode to ensure low power dissipation of the NTC resistor as well as saving current. 40 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Due to self-heating of the IC, the NTC bias current changes. This can be compensated for by calculating what the expected temperature is for the IC, and therefore, what the exact NTC bias current is. Doing this provides a higher accuracy for the thermal sensing: TJ = TA + BJAx(VOUTxIOUTxE) If an LED becomes open-circuit during adaptive loop control operation, then VREG_IN increases until the OVP_D threshold is reached. The OVP_D event is logged in STATUS1 after the debounce timer expires. When an OVP_D condition exists the regulator and DC-DC converter is disabled Thermal Shutdown where: VOUT is the expected output voltage for given setting. Thermal shutdown limits total power dissipation in the IC. When the junction temperature exceeds +160NC (typ), the device turns off, allowing the IC to cool. See STATUS1 register. IOUT is the programmed output current for the given setting. When a thermal shutdown condition exists the regulator and DC-DC converter is disabled. TA is the ambient temperature. BJA is 46NC/W (determined by the package type). E is the system (DCDC converter + current regulator) efficiency. Once the TJ is calculated then the correct NTC bias current level can be calculated: NTC_BIAS = NTC_BIAS_25C + NTC_T_COM x(Tj-25) where: NTC_BIAS is the output bias current for given junction temperature. NTC_BIAS_25C is the bias current at TA = +25NC. NTC_T_COM is the temperature compensation factor. Short and Open LED Detection The IC includes a comparator that detects if the LED output is shorted. If the voltage across the LED is less than 1V, then bit[7:6] in STATUS1 is set after the debounce time expires, LED1_SHORT, LED2_SHORT. When the IC detects the short, only that current regulator is disabled. I2C Serial Interface An I2C-compatible, 2-wire serial interface controls the step-up converter output voltage, flash and torch current settings, flash duration, and other parameters. The serial bus consists of a bidirectional serial-data line (SDA) and a serial-clock input (SCL). The IC is a slave-only device, relying upon a master to generate a clock signal. The master initiates data transfer to and from the IC and generates SCL to synchronize the data transfer (Figure 13). I2C is an open-drain bus. Both SDA and SCL are bidirectional lines, connected to a positive supply voltage through a pullup resistor. They both have Schmitt triggers and filter circuits to suppress noise spikes on the bus to assure proper device operation. A bus master initiates communication with the IC as a slave device by issuing a START condition followed by the IC's address. The IC's address byte consists of 7 address bits and a read/ write bit (R/W). After receiving the proper address, the IC issues an acknowledge bit by pulling SDA low during the ninth clock cycle. Figure 13 SDA tSU,STA tSU,DAT tLOW tBUF tHD,STA tHD,DAT tSU,STO tHIGH SCL tHD,STA tR tF START CONDITION REPEATED START CONDITION STOP CONDITION START CONDITION Figure 13. 2-Wire Serial Interface Timing Detail Maxim Integrated 41 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators I2C Slave Address The IC acts as a slave transmitter/receiver. Its slave address is 0x94h for write operations and 0x95h for read operations. I2C Bit Transfer Each data bit, from the most significant bit to the least significant bit, is transferred one by one during each clock cycle. During data transfer, the SDA signal is allowed to change only during the low period of the SCL clock and it must remain stable during the high period of the SCL clock (Figure 14). START and STOP Conditions Both SCL and SDA remain high when the bus is not busy. The master signals the beginning of a transmission with a START (S) condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the IC, it issues a STOP (P) condition by transitioning SDA from low to high while SCL is high. The bus is then free for another transmission (Figure 15). Both START and STOP conditions are generated by the bus master. Acknowledge The acknowledge bit is used by the recipient to handshake the receipt of each byte of data Figure 16. After data transfer, the master generates the acknowledge clock pulse and the recipient pulls down the SDA line during this acknowledge clock pulse so that the SDA line stays low during the high duration of the clock pulse. When the master transmits the data to the IC, it releases the SDA line and the IC takes the control of the SDA line and generates the acknowledge bit. When SDA remains Figure 14 SCL SDA START CONDITION (S) DATA LINE STABLE DATA VALID DATA ALLOWED TO CHANGE START CONDITION (S) Figure 14. Bit Transfer Figure 15 Figure 16 SDA SDA OUTPUT FROM TRANSMITTER SCL SDA OUTPUT FROM RECEIVER SCL FROM MASTER START CONDITION Figure 15. START and STOP Conditions Maxim Integrated STOP CONDITION START CONDITION D7 D6 D0 NOT ACKNOWLEDGE 1 2 8 9 ACKNOWLEDGE CLOCK PULSE FOR ACKNOWLEDGEMENT Figure 16. Acknowledge 42 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators high during this 9th clock pulse, this is defined as the not acknowledge signal. The master can then generate either a STOP condition to abort the transfer, or a repeated START condition to start a new transfer. Write Operations The IC recognizes the write byte protocol as defined in the SMBus specification and shown in section A of Figure 17. The write byte protocol allows the I2C master device to send 1 byte of data to the slave device. The write byte protocol requires a register pointer address for the subsequent write. The IC acknowledges any register pointer even though only a subset of those registers actually exists in the device. The write byte protocol is as follows: 1. The master sends a start command. 2. The master sends the 7-bit slave address followed by a write bit. 3. The addressed slave asserts an acknowledge by pulling SDA low. 7. The slave updates with the new data. 8. The slave acknowledges the data byte. 9. The master sends a STOP condition. In addition to the write-byte protocol, the IC can write to multiple registers as shown in section B of Figure 17. This protocol allows the I2C master device to address the slave only once and then send data to a sequential block of registers starting at the specified register pointer. Use the following procedure to write to a sequential block of registers: 1. The master sends a start command. 2. The master sends the 7-bit slave address followed by a write bit. 3. The addressed slave asserts an acknowledge by pulling SDA low. 4. The master sends the 8-bit register pointer of the first register to write. 5. The slave acknowledges the register pointer. 4. The master sends an 8-bit register pointer. 6. The master sends a data byte. 5. The slave acknowledges the register pointer. 7. The slave updates with the new data. 6. The master sends a data byte. 8. The slave acknowledges the data byte. Figure 17 LEGEND MASTER TO SLAVE SLAVE TO MASTER A. WRITING TO A SINGLE REGISTER WITH THE "WRITE BYTE" PROTOCOL 1 7 1 1 8 1 8 1 1 S SLAVE ADDRESS 0 A REGISTER POINTER A DATA A P NUMBER OF BITS R/W B. WRITING TO MULTIPLE REGISTERS 1 7 1 1 8 1 8 1 8 1 S SLAVE ADDRESS 0 A REGISTER POINTER X A DATA X A DATA X+1 A 8 1 8 1 NUMBER OF BITS DATA X+n-1 A DATA X+n A NUMBER OF BITS R/W P Figure 17. Write to the IC Maxim Integrated 43 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators 9. Steps 6 to 8 are repeated for as many registers in the block with the register pointer automatically incremented each time. In addition, the IC can read a block of multiple sequential registers as shown in section B of Figure 18. Use the following procedure to read a sequential block of registers: 10.The master sends a STOP condition. 1. The master sends a start command. Read Operations The method for reading a single register (byte) is shown in section A of Figure 18. To read a single register: 2. The master sends the 7-bit slave address followed by a write bit. 1. The master sends a start command. 3. The addressed slave asserts an acknowledge by pulling SDA low. 2. The master sends the 7-bit slave address followed by a write bit. 4. The master sends an 8-bit register pointer of the first register in the block. 3. The addressed slave asserts an acknowledge by pulling SDA low. 5. The slave acknowledges the register pointer. 4. The master sends an 8-bit register pointer. 5. The slave acknowledges the register pointer. 7. The master sends the 7-bit slave address followed by a read bit. 6. The master sends a repeated START condition. 8. The slave assets an acknowledge by pulling SDA low. 7. The master sends the 7-bit slave address followed by a read bit. 9. The slave sends the 8-bit data (contents of the register). 8. The slave assets an acknowledge by pulling SDA low. 11.Steps 9 and 10 are repeated for as many registers in the block, with the register pointer automatically incremented each time. 6. The master sends a repeated START condition. 10.The master assets an acknowledge by pulling SDA low. 9. The slave sends the 8-bit data (contents of the register). 10.The master assets an acknowledge by pulling SDA low. 12.The master sends a STOP condition. 11.The master sends a STOP condition. Figure 18 LEGEND MASTER TO SLAVE SLAVE TO MASTER A. READING A SINGLE REGISTER 1 7 1 1 8 1 S SLAVE ADDRESS 0 A REGISTER POINTER 1 A Sr 7 1 1 8 SLAVE ADDRESS 1 A DATA 7 1 1 8 SLAVE ADDRESS 1 A DATA X R/W NUMBER OF BITS NA R/W B. READING MULTIPLE REGISTERS 1 7 1 1 8 S SLAVE ADDRESS 0 A REGISTER POINTER X R/W P 1 8 DATA X+1 1 A Sr 8 A DATA X+n-1 R/W NUMBER OF BITS A NUMBER OF BITS 8 A DATA X+n NA P Figure 18. Read from the IC Maxim Integrated 44 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 1. I2C Register Map ADDRESS REGISTER NAME 0x00 CHIP_ID1 DIE_TYPE[7:4] DIE_TYPE[3:0] 0x01 CHIP_ID2 DIE_DASH[3:0] DIE_REV[3:0] 0x02 STATUS1 0x03 0x04 B7 B6 B5 B4 B3 IN_UVLO_ THERM B2 NTC_ THERM B0 OVP_A OVP_D ILIM nRESET LED1_SHORT LED2_SHORT REG_IN_UVLO STATUS2 MAXFLASH DONE TX1_MASK IFLASH1 FLASH1_EN FLASH1[5:0] 0x05 IFLASH2 FLASH2_EN FLASH2[5:0] 0x06 ITORCH1 TORCH1_EN TORCH1_5:0] TORCH1_ DIM 0x07 ITORCH2 TORCH2_EN TORCH2_5:0] TORCH2_ DIM 0x08 MODE_SEL TORCH_EN_PD FLASH_STB_PD NTC_SHORT B1 TX2_MASK FLASH_TMR TORCH_TMR TORCH_MODE[2:0] FLASH_MODE[2:0] 0x09 TX1_MASK TX1_MASK_EN TX1_MASK_PD FLASH_TX1_MASK[5:0] 0x0A TX2_MASK TX2_MASK_EN TX2_MASK_PD FLASH_TX2_MASK[5:0] 0x0B FLASH_ RAMP_SEL FLASH_RU[2:0] FLASH_RD[2:0] 0x0C TORCH_ RAMPSEL TORCH_RU[2:0] TORCH_RD[2:0] 0x0D FLASH_TMR_ FLASH_TMR_ CNTL CNTL FLASH_TMR[6:0] 0x0E TORCH_ TMR_CNTL TORCH_TMR_ CNTL 0x10 MAXFLASH1 0x11 MAXFLASH2 0x12 MAXFLASH3 MAX_FLASH1_IMIN[7:0] 0x13 MAXFLASH4 MAX_FLASH2_IMIN[7:0] TORCH_TMR[4:0] MAXFLASH_HYS[2:0] MAXFLASH_TH[4:0] LB_TMR_R[3:0] 0x14 NTC 0x15 DCDC_CNTL1 OVP_TH[1:0] 0x16 DCDC_CNTL2 DCDC_ADPT_REG[1:0] 0x17 DCDC_ILIM 0x18 DCDC_OUT DCDC_OUT[7:0] 0x19 DCDC_OUT_ MAX DCDC_OUT_MAX[7:0] Maxim Integrated NTC_EN LB_TMR_F[3:0] NTC_TH_FLASH[2:0] NTC_TH_TORCH[2:0] FREQ_PWM[1:0] DCDC_GAIN DCDC_OPERATION[2:0] DCDC_ILIM[1:0] DCDC_MODE[1:0] F_SCALE [1:0] DCDC_SS[5:0] 45 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 2. CHIP_ID1 Register Name CHIP_ID1 Address 0x00h Reset Value 0x91 Type Read only Reset Conditions -- BIT NAME DESCRIPTION DEFAULT VALUE B7 MSB B6 B5 DIE_TYPE[7:4] BCD character 9 1001 DIE_TYPE[3:0] BCD character 1 0001 B4 B3 B2 B1 B0 LSB This register contains manufacture die type information. Table 3. CHIP_ID2 Register Name CHIP_ID2 Address 0x01h Reset Value N/A Type Read only Reset Conditions -- BIT NAME DESCRIPTION DEFAULT VALUE B7 MSB B6 B5 DIE_DASH[3:0] BCD character representing dash number N/A BCD character representing silicon revision N/A B4 B3 B2 B1 DIE_REV[3:0] B0 LSB This register contains version control. Maxim Integrated 46 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 4. STATUS1 Register Name STATUS1 Address 0x02h Reset Value 0x00h Type Read only Reset Conditions Reset upon read operation and on VDD < VDD_UVLO. Fault conditions must be cleared before new event can take place. DESCRIPTION DEFAULT VALUE BIT NAME B7 MSB LED1_SHORT LED1 Current Regulator Output Status 0 = No shorted LED detected. 1 = Shorted LED detected. 0 B6 LED2_SHORT LED2 Current Regulator Output Status 0 = No shorted LED detected. 1 = Shorted LED detected. 0 B5 REG_IN_UVLO Indication if REG_IN Input Support is Valid 0 = Valid power at REG_IN. 1 = No valid power at REG_IN. 0 Indication if IN is Valid or Internal Die Temperature is Fault 0 = Valid power at IN and No temperature fault has occurred. 1 = No valid power at IN or temperature fault has occurred. 0 B4 IN_UVLO_THERM B3 NTC_THERM Indication of Status of NTC Resistor 0 = NTC within normal operating range. 1 = NTC over temperature detected. 0 B2 NTC_SHORT Indication of Status of NTC 0 = NTC not shorted to ground. 1 = NTC shorted to ground detected. 0 B1 OVP_A Overvoltage Condition Caused by Analog Control Loop 0 = No OVP_A detected. 1 = OVP_A detected. 0 B0 LSB OVP_D Overvoltage Condition Caused by Digital Control Loop 0 = No OVP_D detected. 1 = OVP_D detected. 0 This register contains status of IC. Maxim Integrated 47 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 5. STATUS2 Register Name STATUS2 Address 0x03h Reset Value 0x01h Type Read only Reset Conditions Reset upon read operation and on VDD < VDD_UVLO or new flash/torch event triggered. BIT NAME B7 MSB MAXFLASH DESCRIPTION DEFAULT VALUE Indication of Status of MAXFLASH 0 = MAXFLASH has not occurred during last FLASH event. 1 = MAXFLASH has occurred during last FLASH event. 0 This is a Simple Indication Where or Not Torch/Flash Event is Done or Not 0 = Torch/flash event in progress. 1 = Torch/flash event is completed. 0 B6 DONE B5 TX1_MASK Indication of TX1_MASK 0 = TX1_MASK has not occurred during last FLASH event. 1 = TX1_MASK has occurred during last FLASH event. 0 B4 TX2_MASK Indication of TX2_MASK 0 = TX2_MASK has not occurred during last FLASH event. 1 = TX2_MASK has occurred during last FLASH event. 0 FLASH_TMR Indication of Flash Timer (Only Valid When Operating in Maximum Timer Mode) 0 = Flash timer did not expire during last Flash sequence. 1 = Flash timer expired during last flash sequence. 0 B2 TORCH_TMR Indication of Torch Timer (Only Valid When Operating in Maximum Timer Mode) 0 = Torch timer did not expire during last torch sequence. 1 = Torch timer expired during last torch sequence. 0 B1 ILIM Inductor Current Limit Status 0 = Inductor peak current limit not reached. 1 = Inductor peak current limit reached. 0 B0 LSB nRESET Indication if Register has been Reset Since Last Operation 0 = I2C registers not reset. 1 = I2C registers reset. Reset upon read. 1 B3 This register contains status of IC. Maxim Integrated 48 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 6. IFLASH1 Register Name IFLASH1 Address 0x04h Reset Value 0x29h Type Read/write Reset Conditions FLASH1_EN is reset upon UVLO, VDD < VDD_UVLO, or LED1 fault for flash mode. BIT NAME B7 MSB FLASH1_EN B6 -- DESCRIPTION DEFAULT VALUE Enable of Flash Mode for FLED1 Current Regulator 0 = FLED1 disabled in flash mode. 1 = FLED1 enabled in flash mode. 0 -- 0 B5 B4 B3 B2 B1 B0 LSB FLASH1[5:0] Setting Flash Current 000000 = 15.625mA 000001 = 31.25mA ... 111110 = 984.375mA 111111 = 1000mA 101001 This register contains control output current for flash mode. Maxim Integrated 49 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 7. IFLASH2 Register Name IFLASH2 Address 0x05h Reset Value 0x29h Type Read/Write Reset Conditions FLASH2_EN is reset upon UVLO, VDD < VDD_UVLO, or LED2 fault for flash mode. BIT NAME B7 MSB FLASH2_EN B6 -- B5 B4 B3 B2 FLASH2[5:0] B1 B0 LSB DESCRIPTION DEFAULT VALUE Enabling Flash Mode for FLED2 Current Regulator 0 = FLED2 disabled in flash mode. 1 = FLED2 enabled in flash mode. 0 -- 0 Setting Flash Current 000000 = 15.625mA 000001 = 31.25mA ... 111110 = 984.375mA 111111 = 1000mA 101001 This register contains control output current for flash mode. Maxim Integrated 50 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 8. ITORCH1 Register Name ITORCH1 Address 0x06h Reset Value 0x00h Type Read/write Reset Conditions TORCH1_EN is reset upon UVLO, VDD < VDD_UVLO, or LED1 fault for torch mode. BIT NAME B7 MSB TORCH1_EN Enabling Torch Mode for FLED1 Current Regulator 0 = FLED1 disabled in torch mode. 1 = FLED1 enabled in torch mode. TORCH1[5:0] Setting TORCH1 Current DAC Mode 000000 = 3.91mA 000001 = 7.8125mA ... 111110 = 246.1mA 111111 = 250.0mA PWM Mode Output current XXX000 = 125mA duty cycle XXX001 = 250mA duty cycle ... XXX110 = 875mA duty cycle XXX111 = 1000.00mA duty cycle Duty Cycle 000XXX = 3.125% duty cycle 001XXX = 6.25% duty cycle ... 110XXX = 21.875% duty cycle 111XXX = 25.000% duty cycle TORCH1_DIM Select DAC or PWM Dimming for Torch 0 = DAC 1 = PWM B6 B5 B4 B3 B2 B1 B0 LSB DESCRIPTION DEFAULT VALUE 0 000000 0 This register contains output current for torch mode. Maxim Integrated 51 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 9. ITORCH2 Register Name ITORCH2 Address 0x07h Reset Value 0x00h Type Read/write Reset Conditions TORCH2_EN is reset upon UVLO, VDD < VDD_UVLO, or LED2 fault for torch mode BIT NAME B7 MSB TORCH2_EN Enabling Torch Mode for FLED2 Current Regulator 0 = FLED2 disabled in torch mode. 1 = FLED2 enabled in torch mode. TORCH2[5:0] Setting TORCH2 Current DAC Mode 000000 = 3.91mA 000001 = 7.8125mA ... 111110 = 246.1mA 111111 = 250.0mA PWM Mode Output current XXX000 = 125mA duty cycle XXX001 = 250mA duty cycle ... XXX110 = 875mA duty cycle XXX111 = 1000.00mA duty cycle Duty Cycle 000XXX = 3.125% duty cycle 001XXX = 6.25% duty cycle ... 110XXX = 21.875% duty cycle 111XXX = 25.000% duty cycle TORCH2_DIM Select DAC or PWM Dimming for Torch 0 = DAC 1 = PWM B6 B5 B4 B3 B2 B1 B0 LSB DESCRIPTION DEFAULT VALUE 1 000000 0 This register contains output current for torch mode. Maxim Integrated 52 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 10. MODE_SEL Register Name MODE_SEL Address 0x08h Reset Value 0xC0h Type Read/write Reset Conditions TORCH_MODE, FLASH_MODE is reset upon UVLO, VDD < VDD_UVLO, THERM fault, or OVP fault BIT B7 MSB B6 NAME DESCRIPTION DEFAULT VALUE TORCH_EN_PD On/Off Control for Pulldown Resistor of TORCH_EN Input 0 = Not enabled. 1 = Enabled. 1 FLASH_STB_PD On/Off Control for Pulldown Resistor of FLASH_STB Input 0 = Not enabled. 1 = Enabled. 1 TORCH_MODE[2:0] 000 = Torch mode disabled. 001 = Torch mode enabled using TORCH_EN 010 = Torch mode enabled using FLASH_STB 011 = Torch mode enabled using TORCH_EN or FLASH_STB 100 = Torch mode enabled using TORCH_EN and FLASH_STB 101 = Torch mode enabled regardless of logic inputs 110 = Torch mode enabled regardless of logic inputs 111 = Torch mode enabled regardless of logic inputs 001 FLASH_MODE[2:0] 000 = Flash mode disabled. 001 = Flash mode enabled using TORCH_EN 010 = Flash mode enabled using FLASH_STB 011 = Flash mode enabled using TORCH_EN or FLASH_STB 100 = Flash mode enabled using TORCH_EN and FLASH_STB 101 = Flash mode enabled regardless of logic inputs 110 = Flash mode enabled regardless of logic inputs 111 = Flash mode enabled regardless of logic inputs 010 B5 B4 B3 B2 B1 B0 LSB This register control the mode of operation. Maxim Integrated 53 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 11. TX1_MASK Register Name TX1_MASK Address 0x09h Reset Value 0xC0h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO NAME B7 MSB TX1_MASK_EN On/Off Control for TX1_MASK 0 = Not enabled. 1 = Enabled. 1 B6 TX1_MASK_PD Enable/Disable Pulldown Resistor for TX1_MASK 0 = Not enabled. 1 = Enabled. 1 B5 B4 B3 B2 B1 B0 LSB FLASH_TX1_MASK[5:0] DESCRIPTION DEFAULT VALUE BIT Setting Maximum Flash Current During TX1_MASK Event 000000 = 15.625mA 000001 = 31.25mA ... 111110 = 984.375mA 111111 = 1000mA 000000 This register contains control output current for flash mode. Maxim Integrated 54 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 12. TX2_MASK Register Name TX2_MASK Address 0x0Ah Reset Value 0xC0h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO NAME B7 MSB TX2_MASK_EN On/Off Control for TX2_MASK 0 = Not enabled. 1 = Enabled. 1 B6 TX2_MASK_PD Enable/Disable Pulldown Resistor for TX2_MASK 0 = Not enabled. 1 = Enabled. 1 B5 B4 B3 B2 FLASH_TX2_MASK[5:0] B1 B0 LSB DESCRIPTION DEFAULT VALUE BIT Setting Maximum Flash Current During TX2_MASK Event 000000 = 15.625mA 000001 = 31.25mA ... 111110 = 984.375mA 111111 = 1000mA 000000 This register contains control output current for flash mode. Maxim Integrated 55 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 13. FLASH_RAMP_SEL Register Name FLASH_RAMP_SEL Address 0x0Bh Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB -- B6 B5 FLASH_RU[2:0] B4 B3 -- B2 B1 FLASH_RD[2:0] B0 LSB DESCRIPTION -- Selection of Flash Ramp-Up Rate 000 = 384Fs 001 = 640Fs 010 = 1152Fs 011 = 2176Fs 100 = 4224Fs 101 = 8.320Fs 110 = 16.512ms 111 = 32.896ms -- Selection of Flash Ramp-Down Rate 000 = 384Fs 001 = 640Fs 010 = 1152Fs 011 = 2176Fs 100 = 4224Fs 101 = 8.320Fs 110 = 16.512ms 111 = 32.896ms DEFAULT VALUE 0 000 0 000 This register controls the ramping. Maxim Integrated 56 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 14. TORCH_RAMP_SEL Register Name TORCH_RAMP_SEL Address 0x0Ch Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB -- B6 B5 TORCH_RU[1:0] B4 B3 -- B2 B1 TORCH_RD[1:0] B0 LSB DESCRIPTION DEFAULT VALUE 0 Selection of Torch Ramp-Up Rate 000 = 16.392ms 001 = 32.776ms 010 = 65.544ms 011 = 131.08ms 100 = 262.152ms 101 = 524.296ms 110 = 1.048s 111 = 2.097s -- Selection of Torch Ramp-Down Rate 000 = 16.392ms 001 = 32.776ms 010 = 65.544ms 011 = 131.08ms 100 = 262.152ms 101 = 524.296ms 110 = 1.048s 111 = 2.097s 000 0 000 This register controls the ramping. Maxim Integrated 57 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 15. FLASH_TMR_CNTL Register Name FLASH_TMR_CNTL Address 0x0Dh Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB FLASH_TMR_CNTL B6 B5 B4 B3 B2 B1 FLASH_TMR[6:0] B0 LSB DESCRIPTION Select Timer Mode for Flash Timer 0 = One-shot timer mode 1 = Maximum timer mode Selecting for Flash Timer 0000000 = 0.128ms 0000001 = 0.384ms 0000010 = 0.640ms 0000011 = 0.896ms 0000100 = 1.41ms 0000101 = 1.92ms 0000101 = 1.92ms 0001110 = 2.43ms 0000111 = 2.94ms 0001000 = 3.97ms 0001001 = 4.99ms ... (1.024ms step size) 0001110 = 10.11ms 0001111 = 11.14ms 0010000 = 13.18ms 0010001 = 15.23ms ... (2.048ms step size) 0011110 = 41.86ms 0011111 = 43.90ms 0100000 = 48.00ms 0100001 = 52.09ms ... (4.096ms step size) 0111110 = 170.88ms 0111111 = 174.98ms 1000000 = 183.17ms 1000001 = 191.36ms ... (8.192ms step size) 1111110 = 691.07ms 1111111 = 699.26ms DEFAULT VALUE 0 0000000 This register contains control information for flash timer. Maxim Integrated 58 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 16. TORCH_TMR_CNTL Register Name TORCH_TMR_CNTL Address 0x0Eh Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB TORCH_TMR_CNTL B6 B5 B4 TORCH_TMR[4:0] B3 B2 DESCRIPTION Select Timer Mode for Torch Timer 0 = One-shot timer mode. 1 = Timer mode disabled. Selecting for Torch Timer 00000 = 122.88ms ... (131.072ms step size) 00011 = 516.096ms ... (262.144 step size) 00100 = 778.24ms 00111 = 1564.67ms ... (262.144 step size) 01000 = 2088.96ms 01111 = 5758.976ms ... (524.288ms step size) 10000 = 6807.552ms 11110 = 21487.616ms 11111 = 22536.192ms ... (1048.576ms step size) DEFAULT VALUE 0 00000 B1 -- -- 0 B0 LSB -- -- 0 This register contains control information for torch timer. Maxim Integrated 59 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 17. MAXFLASH1 Register Name MAXFLASH1 Address 0x10h Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB B6 MAXFLASH_HYS[2:0] B5 B4 B3 B2 B1 B0 LSB MAXFLASH_TH[4:0] DESCRIPTION Selects Hysteresis for MAXFLASH 000 = Off, LED current only allowed to decrease 001 = 50mV 010 = 100mV 110 = 300mV 111 = 350mV Selects MAXFLASH Threshold 00000 = Off, MAXFLASH disabled. 00001 = 2.40V 00010 = 2.433V ... 11110 = 3.366V 11111 = 3.40V DEFAULT VALUE 000 000000 This register contains control information for MAXFLASH. Maxim Integrated 60 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 18. MAXFLASH2 Register Name MAXFLASH2 Address 0x11h Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B5 LB_TMR_R[3:0] 0000 LB_TMR_F[3:0] Selects MAXFLASH Timer for Falling Input Voltage 0000 = 256Fs 0001 = 512Fs ... 1110 = 1792Fs 1111 = 2048Fs 0000 B4 B3 B2 B1 B0 LSB DEFAULT VALUE Selects MAXFLASH Timer for Rising Input Voltage 0000 = 256Fs 0001 = 512Fs ... 1110 = 1792Fs 1111 = 2048Fs B7 MSB B6 DESCRIPTION This register contains control information for MAXFLASH. Maxim Integrated 61 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 19. MAXFLASH3 Register Name MAXFLASH3 Address 0x12h Reset Value 0x3Fh Type Read only Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME DESCRIPTION DEFAULT VALUE B7 MSB B6 B5 B4 B3 MAX_FLASH1_IMIN[7:0] Minimum output current logged for LED (FLED1) during a MAXFLASH event 00111111 B2 B1 B0 LSB This register contains control information for MAXFLASH. Table 20. MAXFLASH4 Register Name MAXFLASH4 Address 0x13h Reset Value 0x3Fh Type Read only Reset Conditions -- BIT NAME DESCRIPTION DEFAULT VALUE B7 MSB B6 B5 B4 B3 MAX_FLASH2_IMIN[7:0] Minimum output current logged for LED (FLED2) during a MAXFLASH event 00111111 B2 B1 B0 LSB This register contains control information for MAXFLASH Maxim Integrated 62 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 21. NTC Register Name NTC Address 0x14h Reset Value 0x00h Type Read/Write Reset Conditions NTC_EN bit is cleared on NTC_SHORT detected. Reset upon VDD < VDD_UVLO. BIT NAME B7 MSB NTC_EN B6 B5 0 NTC_TH_FLASH[2:0] 000 NTC_TH_TORCH[2:0] Selects Threshold for Hot for Torch Mode 000 = 200mV 001 = 250mV ... 110 = 500mV 111 = 550mV 000 B3 B1 On/Off Control of NTC Input 0 = Disabled. 1 = Enabled. DEFAULT VALUE Selects Threshold for Hot for Flash Mode 000 = 200mV 001 = 250mV ... 110 = 500mV 111 = 550mV B4 B2 DESCRIPTION B0 LSB 0 This register contains control information for NTC function. Maxim Integrated 63 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 22. DCDC_CNTL1 Register Name DCDC_CNTL1 Address 0x15h Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB OVP_TH[1:0] B6 DESCRIPTION DEFAULT VALUE Selects Overvoltage Threshold for the DC-DC Converter Output Voltage 00 = 4.50V 01 = 4.80V 10 = 5.10V 11 = 5.40V 00 B5 -- -- 0 B4 -- -- 0 Selection of Frequency for PWM of Current Regulators 00 = 7.8kHz 01 = 1.9kHz 10 = 488Hz 11 = 122Hz 00 00 = Adaptive mode. DCDC is enabled together with current regulators. 01 = Prebiased adaptive mode. Output is prebiased and DC-DC is enabled together with current regulators. 10 = Forced active mode with output regulating at DCDC_SS. 11 = Dropout mode. 00 B3 FREQ_PWM[1:0] B2 B1 DCDC_MODE B0 LSB This register contains control information for DC-DC converter. Maxim Integrated 64 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 23. DCDC_CNTL2 Register Name DCDC_CNTL2 Address 0x16h Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME B7 MSB DCDC_ADPT_REG[1:0] B6 B5 DCDC_GAIN DEFAULT VALUE DESCRIPTION Sets the Adaptive Regulation Threshold for the DC-DC Converter 00 = 120mV 01 = 150mV 10 = 180mV 11 = 210mV 00 0 = Standard 1 = Enhancement 0 Mode for DC-DC Converter B4 B3 DCDC_OPERATION[2:0] B2 B4, B3, B2 Mode Frequency DC Min (%) 000 SKIP 1MHz Fixed 3.125 001 SKIP 4MHz Auto Adjust 3.125 010 FPWM 4MHz Fixed 12.50 011 FPWM 4MHz Auto Adjust 3.125 100 FPWM 1MHz Fixed 3.125 101 FPWM 2MHz Fixed 12.50 110 FPWM 2MHz Auto Adjust 3.125 111 SKIP 2MHz Auto Adjust 3.125 000 B1 B0 LSB -- -- 00 This register contains control information for DC-DC converter. Maxim Integrated 65 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 24. DCDC_LIM Register Name DCDC_LIM Address 0x17h Reset Value 0x00h Type Read/write Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME DESCRIPTION DEFAULT VALUE DCDC_ILIM[1:0] Selects Current Limit for Low-Side Switch (per phase) 00 = 1.25 01 = 1.5 10 = 1.75 11 = 2.0 00 DCDC_SS[5:0] Set the Soft-Start Threshold for the DC-DC Converter 000000 = 2.3V 000001 = 2.35V ... 111110 = 5.15V 111111 = 5.2V 000000 B7 MSB B6 B5 B4 B3 B2 B1 B0 LSB This register contains control information for DC-DC converter. Maxim Integrated 66 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 25. DCDC_OUT Register Name DCDC_OUT Address 0x18h Reset Value 0x00h Type Read only Reset Conditions Reset upon VDD < VDD_UVLO BIT NAME DESCRIPTION DEFAULT VALUE B7 MSB B6 B5 B4 B3 B2 B1 DCDC_OUT[7:0] Readback Information Regarding Adaptive Regulation Output Voltage 00000000 = 2.3V 00000001 = 2.3125V ... 11111110 = 5.1875V 11111111 = 5.2V 00000000 B0 LSB This register contains control information about the actual regulation threshold for the DCD converter during adaptive regulation. Maxim Integrated 67 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 26. DCDC_OUT_MAX Register Name DCDC_OUT_MAX Address 0x19h Reset Value 0x00h Type Read only Reset Conditions Reset upon triggering torch or flash mode and VDD < VDD_ BIT UVLO NAME DESCRIPTION DEFAULT VALUE DCDC_OUT_MAX[7:0] Readback Information Regarding Adaptive Regulation Output Voltage 00000000 = 2.3V 00000001 = 2.3125V ... 11111110 = 5.1875V 11111111 = 5.2V 00000000 B7 MSB B6 B5 B4 B3 B2 B1 B0 LSB This register contains control information about the maximum regulation threshold for the DCD converter during adaptive regulation. Maxim Integrated 68 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Applications Information Programming the I2C Registers It is critical to program the IC in the correct sequence to ensure proper operation. Changing any register values other than the DCDC_ MODE bits in the DCDC_CNTL1 register during a flash or torch event is not advised. Poll the STATUS2 register to wait for the DONE bit to be asserted before changing values. Sequencing can be divided in to three groups flash and torch mode and DC-DC output voltage. For flash mode, the following sequence is recommended: 1. Clear any pending fault status by reading the STATUS1 register. Failing to do this can result in incorrect values written is some of the registers. For example, failing to clear a FLED1 or FLED2 fault clears the FLED1_EN or FLED2_EN, respectively, disabling the current regulators remain disabled until the FLED_ fault is cleared in the STATUS1 register. 2. Ensure that flash mode is not enabled, by setting the FLASH_MODE bits to 000 in the MODE_SEL register. Ensure the DCDC_MODE bits are 00 in the DCDC_ CNTL1 register. 3. If the TX_MASK function is required for flash operation, write the appropriate values into the TX1_MASK and TX2_MASK register. This register does not need to be updated if current values are already set. 4. Select the ramp rate in the FLASH_RAMP_SEL register for ramping up/down the FLED current. These registers do not need to be updated if current values are already set. 5. Select the flash timer and mode of operation by writing to the FLASH_TMR_CNTL register. This register does not need to be updated if current values are already set. 6. If the MAXFLASH function is required for flash operation, write the appropriate values into the MAXFLASH1 and MAXFLASH2 registers. These registers do not need to be updated if current values are already set. 7. If the NTC function is required for flash operation, write the appropriate values into the NTC register. This register does not have to be updated if current values are already set. Maxim Integrated 8. Select the settings for the DC-DC converter by writing to the DCDC_CNTL2 and DCDC_ILIM registers. These registers do not need to be updated if current values are already set. 9. Select the settings for the flash mode by writing to the FLASH1 and FLASH2 registers. These registers do not need to be updated if current values are already set. 10.Select the settings for the DCDC_CNTL1 register. 11.Select the trigger mode for flash event by writing to the FLASH_MODE bits in the MODE_SEL register. This register does not need to be updated if current values are already set. Now the flash event is ready to be triggered based on the value set for the FLASH_MODE setting. For hardware triggering, set FLASH_MODE = 001, 010, 011, or 100. Flash event is retriggered based on logic input. No update to I2C registers is required. For software triggering, set FLASH_MODE = 101, 110, or 111. Flash event is triggered once FLASH_MODE changes from an external trigger to a software trigger. If an additional flash event is required through a software trigger, the FLASH_MODE needs to be set to 000 first before writing to the software value (101, 110, or 111) to retrigger a new flash event. For torch mode, the following sequence is recommended: 1. Clear any pending fault status by reading the STATUS1 register. Failing to do this can result in incorrect values written to some of the registers. For example, failing to clear a FLED1 or FLED2 fault clears the FLED1_EN or FLED2_EN, respectively, disabling the current regulators that remain disabled until the FLED_ fault is cleared in the STATUS1 register. When the FLED_ fault is cleared, the TORCH_EN can be set. 2. Ensure that torch mode is not enabled by setting the TORCH_MODE to 000 in the MODE_SEL register. Ensure the DCDC_MODE bits are 00 in the DCDC_ CNTL1 register. 3. Select the ramp rate in the TORCH_RAMP_SEL register for ramping up/down the torch FLED current. This register does not need to be updated if current values are already set. 4. Select the torch timer and mode of operation by writing to the TORCH_TMR_CNTL register. This register does not need to be updated if current values are already set. 69 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators 5. If the MAXFLASH function is required for torch operation, write the appropriate values into the MAXFLASH1 and MAXFLASH2 registers. These registers do not need to be updated if current values are already set. 4. Select the settings for DCDC_CNTL1 register including the DCDC_MODE bits. Writing anything other than 00 to the DCDC_MODE bits enables the DC-DC converter. 6. If the NTC function is required for torch operation, write the appropriate values into the NTC register. This register does not need to be updated if current values are already set. During a torch or flash event, the following optional registers can be read: 7. Select the settings for the DC-DC converter by writing to the DCDC_CNTL2 and DCDC_ILIM registers. These registers do not need to be updated if current values are already set. 8. Select the settings for the torch mode by writing to the TORCH1 and TORCH2 registers. These registers do not need to be updated if current values are already set. 9. Select the settings for the DCDC_CNTL1 register. 10.Select the trigger mode for the torch event by writing to the TORCH_MODE bits in the MODE_SEL register. This register does not need to be updated if current values are already set. The DCDC_OUT register contains current information regarding the output voltage settings. The actual output voltage is slightly lower due to the load regulation of the DC-DC converter. It is not required to read this register during a torch or flash event. STATUS1 register contains current information if any fault condition occurs during the torch or flash event. It is optional to read this register during torch or flash event. The STATUS2 register contains information regarding any events that might have happened during a torch or flash event. After a torch or flash event the following optional register can be read: Now the torch event is ready to be triggered based on the value set for the TORCH_MODE setting. The DCDC_OUT_MAX register contains the last adaptive output voltage to which the converter has regulated the output. This information can be used to adjust the DCDC_SS setting. For hardware triggering set TORCH_MODE = 001, 010, 011, or 100. A torch event is retriggered based on logic input. No update to I2C registers is required. The STATUS1 register contains information regarding any fault condition that might have occurred during a torch or flash event. For software triggering, set TORCH_MODE = 101, 110, or 111. A torch event is triggered once TORCH_MODE changes from an external trigger to a software trigger. If an additional torch event is required through a software trigger, the TORCH_MODE needs to be set to 000 first before writing to the software value (101, 110, or 111) to retrigger a new torch event. The STATUS2 register contains information regarding any events that might have happened during a torch or flash event. For DC-DC fixed voltage mode and dropout output voltage, the following sequence is recommended: 1. Clear any pending fault status by reading the STATUS1 register. Failing to do this can result in incorrect values written is some of the registers. 2. Ensure the DCDC_MODE bits are 00 in the DCDC_ CNTL1 register. 3. For fixed output voltage mode, select the settings for the DC-DC converter by writing to the DCDC_CNTL2 and DCDC_ILIM registers. These registers do not have to be updated if current values are already set. Maxim Integrated If the MAXFLASH is enabled, the MAXFLASH3 and MAXFLASH4 registers contain the minimum current setting that the current regulators where regulating to during the MAXFLASH event. The STATUS2 register contains a MAXFLASH bit indicating if the MAXFLASH was active during the torch or flash event. It should be note that during fixed output voltage mode, the output is regulated to the DCDC_SS value that was set during the enabling of the converter. The DCDC_SS value can be updated when the converter is enabled, but this does not impact the output voltage. To change the output voltage, first power down the DC-DC converter (DCD_MODE = 00), then update the DCDC_SS value, and then power it up again (DCDC_MODE = 10). 70 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Output Voltage Operating Range U Inductor value The capability of the DC-DC converter of the IC is depending on following parameters: U Switching frequency U Input voltage The following tables give examples of different operating conditions with the respective input and output voltage limitations. U Output voltage U Efficiency for given range of operation U Peak input current limit of the IC Table 27. Maximum Output Voltage for 2A Output Current as a Function of VIN and IPEAK IPEAK (PER PHASE) 1.25A VIN 1.50A 1.75A 2.00A VOUT max support for 2A output current 2.50V 2.50V 2.69V 3.19V 3.69V 2.60V 2.60V 2.82V 3.34V 3.87V 2.70V 2.70V 2.95V 3.50V 4.05V 2.80V 2.80V 3.08V 3.66V 4.24V 2.90V 2.90V 3.21V 3.82V 4.43V 3.00V 3.00V 3.35V 3.98V 4.62V 3.10V 3.10V 3.48V 4.15V 4.82V 3.20V 3.20V 3.62V 4.32V 5.00V 3.30V 3.30V 3.76V 4.48V 5.00V 3.40V 3.40V 3.90V 4.65V 5.00V 3.50V 3.50V 4.04V 4.82V 5.00V 3.60V 3.60V 4.13V 4.94V 5.00V 3.70V 3.70V 4.22V 5.00V 5.00V 3.80V 3.80V 4.32V 5.00V 5.00V 3.90V 3.90V 4.41V 5.00V 5.00V 4.00V 4.00V 4.50V 5.00V 5.00V 4.10V 4.10V 4.59V 5.00V 5.00V 4.20V 4.20V 4.68V 5.00V 5.00V 4.30V 4.30V 4.76V 5.00V 5.00V 4.40V 4.40V 4.85V 5.00V 5.00V 4.50V 4.50V 4.94V 5.00V 5.00V Note: For fSW = 4MHz, L = 0.5H. Maxim Integrated 71 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 28. Maximum Output Voltage for 1.5A Output Current as a Function of VIN and IPEAK IPEAK (PER PHASE) 1.25A VIN 1.50A 1.75A 2.00A VOUT max support for 1.5A output current 2.50V 2.92V 3.58V 4.25V 4.92V 2.60V 3.05V 3.76V 4.46V 5.00V 2.70V 3.19V 3.93V 4.67V 5.00V 2.80V 3.33V 4.11V 4.88V 5.00V 2.90V 3.47V 4.28V 5.00V 5.00V 3.00V 3.61V 4.46V 5.00V 5.00V 3.10V 3.75V 4.64V 5.00V 5.00V 3.20V 3.90V 4.83V 5.00V 5.00V 3.30V 4.04V 5.00V 5.00V 5.00V 3.40V 4.19V 5.00V 5.00V 5.00V 3.50V 4.33V 5.00V 5.00V 5.00V 3.60V 4.43V 5.00V 5.00V 5.00V 3.70V 4.52V 5.00V 5.00V 5.00V 3.80V 4.62V 5.00V 5.00V 5.00V 3.90V 4.71V 5.00V 5.00V 5.00V 4.00V 4.80V 5.00V 5.00V 5.00V 4.10V 4.89V 5.00V 5.00V 5.00V 4.20V 4.98V 5.00V 5.00V 5.00V 4.30V 5.00V 5.00V 5.00V 5.00V 4.40V 5.00V 5.00V 5.00V 5.00V 4.50V 5.00V 5.00V 5.00V 5.00V Note: For fSW = 4MHz, L = 0.5H. Maxim Integrated 72 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 29. Maximum Output Voltage for 1.0A Output Current as a Function of VIN and IPEAK IPEAK (PER PHASE) 1.25A VIN 1.50A 1.75A 2.00A VOUT max support for 1.0A output current 2.50V 4.38V 5.00V 5.00V 5.00V 2.60V 4.58V 5.00V 5.00V 5.00V 2.70V 4.79V 5.00V 5.00V 5.00V 2.80V 5.00V 5.00V 5.00V 5.00V 2.90V 5.00V 5.00V 5.00V 5.00V 3.00V 5.00V 5.00V 5.00V 5.00V 3.10V 5.00V 5.00V 5.00V 5.00V 3.20V 5.00V 5.00V 5.00V 5.00V 3.30V 5.00V 5.00V 5.00V 5.00V 3.40V 5.00V 5.00V 5.00V 5.00V 3.50V 5.00V 5.00V 5.00V 5.00V 3.60V 5.00V 5.00V 5.00V 5.00V 3.70V 5.00V 5.00V 5.00V 5.00V 3.80V 5.00V 5.00V 5.00V 5.00V 3.90V 5.00V 5.00V 5.00V 5.00V 4.00V 5.00V 5.00V 5.00V 5.00V 4.10V 5.00V 5.00V 5.00V 5.00V 4.20V 5.00V 5.00V 5.00V 5.00V 4.30V 5.00V 5.00V 5.00V 5.00V 4.40V 5.00V 5.00V 5.00V 5.00V 4.50V 5.00V 5.00V 5.00V 5.00V Note: For fSW = 4MHz, L = 0.5H. For conditions other than those specified in the tables above the maximum output voltage that can be supported by the IC can be calculated using following formula: VIN(MIN) 2 IPEAK - x VIN(MIN) x L x fSW 2 VOUT = IOUT(MAX) VOUT cannot exceed OVP_D minus load regulation. Maxim Integrated 73 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Inductor Selection VOUT x IOUT(MAX) VIN(MIN) + IPEAK The IC is designed to use a 0.47FH to 1.0FH inductor per = 2 x x VIN(MIN) 2 x L x fSW phase. Selecting a higher inductance value increases efficiency by reducing inductor peak-to-peak current with where: the trade-off in solution size. L is the inductance chosen. To prevent core saturation, ensure that the inductor-saturation current rating exceeds the peak inductor current for the application. Calculate the worst-case peak inductor current with the following formula: fSW is the actual switching frequency for the IC. E is the DC-DC converter efficiency. See the appropriate typical operating curve. Table 30. Suggested Inductors MANUFACTURER SERIES INDUCTANCE (H) DCR (mI) ISAT (A) DIMENSIONS (LTYP x WTYP x HMAX) (mm) RECOMMENDED INDUCTORS FOR THE ILIM 1.25A SETTING Coilcraft SEMCO PFL1610 0.47 85 1.8 1.8 x 1.0 x 1.0 XPL2010 0.50 0.68 0.82 1.00 40 57 68 89 2.35 1.95 1.65 1.60 2.0 x 1.9 x 1.0 CIG21LR47MNE 0.47 96 1.35 2.0 x 1.25 x 1.0 CIG22L1R0MNE 1.0 60 1.6 2.5 x 2.0 x 1.0 TOKO MDT2012-CR 0.56 65 1.5 2.0 x 1.25 x 1.0 TDK VLS2012 0.47 54 1.85 0.68 72 1.65 0.33 68 2.1 0.5 85 1.48 0.47 1.0 30 60 3.6 2.4 PSB1210T Cyntec PIFE20161B Maxim Integrated 2.0 x 1.6 x 0.95 1.25 x 1.0 x 1.0 2.0 x 1.6 x 1.2 74 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 30. Suggested Inductors (continued) MANUFACTURER SERIES INDUCTANCE (H) DCR (mI) ISAT (A) DIMENSIONS (LTYP x WTYP x HMAX) (mm) RECOMMENDED INDUCTORS FOR THE ILIM 1.5A SETTING Coilcraft TOKO SEMCO TDK PFL1610 0.47 85 1.8 1.8 x 1.0 x 1.0 XPL2010 0.50 0.68 40 57 2.35 1.95 2.0 x 1.9 x 1.0 MDT2012-CR 0.56 65 1.5 2.0 x 1.25 x 1.0 DEM2812C 1.0 66 1.6 3.2 x 3.0 x 1.2 CIG2MWR47MNE 0.47 75 1.8 2.0 x 1.25 x 1.0 0.47 54 1.85 0.68 72 1.65 PSI2520 0.47 40 2.3 2.5 x 2.0 x 1.0 PIFE2520T 0.47 1.0 34 54 4.5 3.5 2.5 x 2.0 x 1.0 PIFE20161B 0.47 1.0 30 60 3.6 2.4 2.0 x 1.6 x 1.2 PSB1210T 0.33 68 2.1 1.25 x 1.0 x 1.0 60 1.8 2.0 x 1.46 x 1.0 VLS2012 Cyntec 2.0 x 1.6 x 0.95 RECOMMENDED INDUCTORS FOR THE ILIM 1.75A SETTING Coilcraft PFL2010 0.47 XPL2010 0.50 40 2.35 2.0 x 1.9 x 1.0 TDK VLS2012 0.47 54 1.85 2. 0x 1.6 x 0.95 SEMCO CIG22HR47 0.47 52 3.8 2.5 x 2.0 x 1.0 PSI2520 0.47 40 2.3 2.5 x 2.0 x 1.0 PSB1210T 0.33 68 2.1 2.5 x 2.0 x 1.0 PIFE2520T 0.47 1.0 34 54 4.5 3.5 2.5 x 2.0 x 1.0 PIFE20161B 0.47 1.0 30 60 3.6 2.4 2.0 x 1.6 x 1.2 Cyntec RECOMMENDED INDUCTORS FOR THE ILIM 2.0A SETTING CoilCraft XPL2010 0.50 40 2.35 2.0 x 1.9 x 1.0 SEMCO CIG22HR47 0.47 52 3.8 2.5 x 2.0 x 1.0 TDK VLF3025 1.0 33 2.0 3.0 x 2.5 x 1.0 Cyntec Maxim Integrated PSI2520 0.47 40 2.3 2.5 x 2.0 x 1.0 PSB1210T 0.33 68 2.1 1.25 x 1.0 x 1.0 PIFE2520T 0.47 1.0 34 54 4.5 3.5 2.5 x 2.0 x 1.0 PIFE20161B 0.47 1.0 30 60 3.6 2.4 2.0 x 1.6 x 1.2 75 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Input Capacitor Selection The input capacitor required consists of two capacitors. One capacitor is used for decoupling the input to IN. The other is for decoupling the inductors to reduce input ripple. The IN should be decoupled using a minimum capacitance of 0.08FF. This capacitor is required to ensure a low noise input to IN and is critical for MAXFLASH and adaptive regulation quality. The input capacitor for the inductor is required to support the ripple current from the DC-DC converter switching. The input capacitor needs to have a minimum capacitance of 4FF. Ensure that with voltage derating that the value of the capacitor is sufficient to ensure stability of the converter. Since capacitors can derate as much as 40% to 60%, a 10FF capacitor is recommended. See Table 31 below for recommended capacitors. Another critical parameter for the input capacitor is that the impedance at 8MHz is as low as possible. Since the ripple frequency of the converter is 2x 4MHZ, choosing an input capacitor with high impedance at this frequency results in increased input ripple, reducing the performance of the IC. Output Capacitor Selection The output capacitor is one of the critical items in determining the output ripple current of the FLED output. The current regulator output ripple current is generated from the voltage ripple existing on the OUT capacitor due to DC-DC step up converter switching. Therefore, the choice of output capacitor has a large impact on the output ripple of the current regulators. In order to ensure low output ripple current, the following steps should be taken: 1. Select an output capacitor with a low ESR. 2. Select an output capacitor with low impedance at the switching frequency. 3. In the PCB layout careful routing between the IC and output capacitors can reduce ripple current. By routing to the output capacitor as a star connection the ripple that is injected into the current regulator is reduced by ILX_xRTRACE1. Even though this is a small reduction in ripple, it still aids in producing a low output ripple current. 4. (Optional) A capacitor at REG_IN can even further reduce the output ripple current. The additional capacitor at REG_IN reduces the overall ESR of the output capacitor by having more capacitors in parallel. Also the connection between the output capacitor and the capacitor at REG_IN acts at a high-frequency filter since the trace acts like an inductor forming a LC filter. This is especial effective in filtering away the switching edges of the DC-DC converter. Figure 19 RTRACE1 OUT_A RTRACE2 OUT_B RTRACE3 The voltage ripple on OUT capacitor is mainly due to the following two factors: REG_IN ESR ESR of the output capacitor. ESR DV across the output capacitor caused by the charge and discharge cycle. Figure 19. Output Capacitor Start Connection Table 31. Suggested Input Capacitors MANUFACTURER ESR (mI at 4HMz) DIMENSIONS (LTYP x WTYP x HMAX) (mm) SERIES CAPACITANCE (F) Samsung CL05A106MP5NUNC 10 9 1.0 x 0.5 x 0.5 Murata GRM188R60J106ME84 10 10 1.6 x 0.6 x 0.085 Samsung CL05A104KA5NNNC 0.1 4.6 1.0 x 0.5 x 0.5 Taiyo Yuden TMK105BJ1040KV 0.1 20 1.0 x 0.5 x 0.5 Murata GRM155R61E104KA87 0.1 15 1.0 x 0.5 x 0.5 Maxim Integrated 76 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Table 32. Suggested Output Capacitors MANUFACTURER ESR (mI at 4HMz) DIMENSIONS (LTYP x WTYP x HMAX = VOLUME) (mm) SERIES CAPACITANCE (F) Samsung CL05A106MP5NUNC 10 9 1.0 x 0.5 x 0.5 Murata GRM188R60J106ME84 10 10 1.6 x 0.6 x 0.085 Samsung CL05A475KP5NRNC 4.7 5 1.0 x 0.5 x 0.5 The output capacitors needs to have a minimum capacitance of 6FF for DCDC_GAIN = 0 and a minimum capacitance of 12FF for DCDC_GAIN = 1 and operating in non adaptive mode. Ensure that with voltage derating that the value of the capacitor is sufficient to ensure stability of the converter. Since capacitors can derate as much as 40% to 60%, a 10FF capacitor for each output is recommended for DCDC_GAIN of 0. With DCDC_GAIN of 1 either a 20FF capacitor or 2x 10FF capacitors at each output is recommended. An optional capacitor at REG_IN of 4.7FF can help increase the performance of the current regulator. See Table 32 for recommended capacitors. PCB Layout Layout is critical for the performance of the IC. Proper layout ensures good thermal conditions for the IC as well as minimizing EMI disturbances and most important good current sharing between the two phases. Bypass IN to AGND with a ceramic capacitor. Ceramic capacitors with X5R and X7R dielectrics are recommended for their low ESR and tighter tolerances over a wide temperature ranges. Place the capacitor as close as possible to the IN input bump with a value recommended in the input capacitor selection section. Place an additional capacitor from IN to PGND,close to the inductor (shared for both phases) with a recommended value give in the input capacitor selection section. Bypass OUT_ to PGND_ with a ceramic capacitor. Ceramic capacitors with X5R and X7R dielectrics are recommended for their low ESR and tighter tolerances over a wide temperature ranges. Place the capacitor as close as possible to the IC. Ensure that the rout- Maxim Integrated ing form IC to output capacitor is as identical for each phase as possible since this yields the best efficiency. The minimum required output capacitor value is given in output capacitor selection section. Ensure that OUT_A and OUT_B are routed directly to the output capacitor before routed to REG_IN. Doing this minimizes the output ripple current on the LED due to voltage ripple on the output capacitor. For enhanced performance of the current regulator, an additional capacitor can be paced at REG_IN_. This reduces the output ripple current of the current regulator and overall enhances the performance of the current regulator. Keep the ground loop among the input, output and the IC as short as possible since this ground plane is carrying the full load current. Keep the connection between the LX_ and inductor as short as possible. Keep the LX_ trace away from noise sensitive traces. Ensure that the layout for each of the phases is as symmetrical as possible since this yields the best current sharing between the two phases. The trace from FLED_ to the anode of the FLED_ can be longer, but keeping this trace low impedance is critical for the efficiency of the applications as well as getting heat transferred away from the IC. Place as much ground as possible around the IC since this enhances the thermal properties of the device. Chip Information PROCESS: BiCMOS 77 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Figure 20 3.0mm CCINut L MDT2012 1.0mm HEIGHT 4.15mm L MDT2012 1.0mm HEIGHT Cout COUT Cout COUT TORCH_ EN PGND_B LX_B OUT_A TX1_ MASK TX2_ MASK FLASH_ STB OUT_B VDD SCL REG_IN NTC IN SDA FLED REG_INI FLED AGND Cout PGND_A Cout LX_A CIN CDD Figure 20. 20-Bump WLP Recommended Layout for 2x1.5A Input Current Limit Maxim Integrated 78 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Simplified Block Diagram 0.47H LX_A PGND_A BATTERY 2.5V TO 5.5V 0.47H OUT_A 4MHz DC-DC STEP UP CONVERTER LX_B 4MHz DC-DC STEP UP CONVERTER PGND_B OUT_B MAX77387 IN REGIN UVLO AND MAXFLASH FLED1 AGND FLED2 VDD SDA SCL TX1_MASK TX2_MASK TORCH_EN REGISTERS AND CONTOL LOGIC FLASH_STB NTC Ordering Information PART TEMP RANGE PIN-PACKAGE MAX77387EWP+T -40NC to +85NC 20 WLP MAX77387EWP+ -40NC to +85NC 20 WLP +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. Maxim Integrated Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 20 WLP W201D2+1 21-0544 Refer to Application Note 1891 79 MAX77387 Dual-Phase Adaptive DC-DC Step-Up Converter With 2x 1000mA High-Side Current Regulators Revision History REVISION NUMBER REVISION DATE 0 7/12 DESCRIPTION Initial release PAGES CHANGED -- Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 (c) 2012 Maxim Integrated 80 Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.