Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter General Description Features The AP3502 is a 340kHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 2A load with high efficiency, excellent line and load regulation. The device integrates N-channel power MOSFET switches with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. * * * * * * * * * * The AP3502 employs complete protection to ensure system security, including output Over Voltage Protection, input Under Voltage LockOut, programmable soft-start, and Over Temperature Protection. AP3502 Input Voltage Range: 4.5V to 18V Fixed 340kHz Frequency High Efficiency: up to 95% Output Current: 2A Current Mode Control Built-in Over Current Protection Built-in Thermal Shutdown Function Built-in UVLO Function Built-in Over Voltage Protection Programmable Soft-start Applications * * * * This IC is available in SOIC-8 package. LCD TV Set Top Box Portable DVD Digital Photo Frame SOIC-8 Figure 1. Package Type of AP3502 May. 2012 Rev. 1. 9 BCD Semiconductor Manufacturing Limited 1 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Pin Configuration M Package (SOIC-8) BS 1 8 SS IN 2 7 EN SW 3 6 COMP GND 4 5 FB Figure 2. Pin Configuration of AP3502 (Top View) Pin Description Pin Number Pin Name 1 BS 2 IN 3 SW 4 GND 5 FB 6 COMP 7 EN 8 SS May. 2012 Function Bootstrap pin. A bootstrap capacitor is connected between the BS pin and SW pin. The voltage across the bootstrap capacitor drives the internal high-side power MOSFET Supply power input pin. A capacitor should be connected between the IN pin and GND pin to keep the input voltage constant Power switch output pin. This pin is connected to the inductor and bootstrap capacitor Ground pin Feedback pin. This pin is connected to an external resistor divider to program the system output voltage. When the FB pin voltage exceeds 1.1V, the over voltage protection is triggered. When the FB pin voltage is below 0.3V, the oscillator frequency is lowered to realize short circuit protection Compensation pin. This pin is the output of the transconductance error amplifier and the input to the current comparator. It is used to compensate the control loop. Connect a series RC network from this pin to GND. In some cases, an additional capacitor from this pin to GND pin is required Control input pin. EN is a digital input that turns the regulator on or off. Drive EN high/low to turn on/off the regulator. Pull up with 100k resistor for automatic startup Soft-start control input pin. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1F capacitor sets the soft-start period to 15ms. To disable the soft-start feature, leave SS unconnected Rev. 1. 9 BCD Semiconductor Manufacturing Limited 2 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Functional Block Diagram 2 IN SHUTDOWN COMPARATOR 1.5V VA INTERNAL REGULATOR 0.3V VB CURRENT SENSE AMPLIFIER SLOP COMP VA + OSCILLATOR SCP 1 90 k/340k BS M1 CLK LOCK COMPARATOR 7 EN S Q R Q 3 PWM COMPARATOR SW M2 2.5V VB 4 1.1V 6 A 8 SS GND EA 5 0. 925V FB 6 COMP Figure 3. Functional Block Diagram of AP3502 Ordering Information AP3502 - Circuit Type G1: Green Package M: SOIC-8 Package Temperature Range SOIC-8 -40 to 85C TR: Tape & Reel Blank: Tube Part Number Marking ID Packing Type AP3502M-G1 3502M-G1 Tube AP3502MTR-G1 3502M-G1 Tape & Reel BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green. May. 2012 Rev. 1. 9 BCD Semiconductor Manufacturing Limited 3 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit IN Pin Voltage VIN -0.3 to 20 V EN Pin Voltage VEN -0.3 to VIN V SW Pin Voltage VSW 21 V BS Pin Voltage VBS -0.3 to VSW+6 V FB Pin Voltage VFB -0.3 to 6 V VCOMP -0.3 to 6 V SS Pin Voltage VSS -0.3 to 6 V Thermal Resistance JA 105 C/W Operating Junction Temperature TJ 150 C Storage Temperature TSTG -65 to 150 C Lead Temperature (Soldering, 10sec) TLEAD 260 C ESD (Human Body Model) VHBM 2000 V ESD (Machine Model) VMM 200 V COMP Pin Voltage Note 1: Stresses greater than 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 under "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum Ratings" for extended periods may affect device reliability. Recommended Operating Conditions Parameter Symbol Min Max Unit Input Voltage VIN 4.5 18 V Operating Ambient Temperature TA -40 85 C May. 2012 Rev. 1. 9 BCD Semiconductor Manufacturing Limited 4 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Electrical Characteristics TA=25C, VIN=VEN=12V, VOUT=3.3V, unless otherwise specified. Parameter Symbol Conditions Min Typ Max Unit 1.2 0.1 18 1.4 10 V mA A SUPPLY VOLTAGE (IN PIN) Input Voltage Quiescent Current Shutdown Supply Current VIN IQ ISHDN 4.5 VFB=1V,VEN=3V VEN=0V UNDER VOLTAGE LOCKOUT Input UVLO Threshold Input UVLO Hysteresis VUVLO VHYS VIN Rising 3.65 4.00 200 4.25 V mV 1.1 1.5 2 V ENABLE (EN PIN) EN Shutdown Threshold Voltage EN Shutdown Threshold Voltage Hysteresis (Note 2) EN Lockout Threshold Voltage EN Lockout Hysteresis 350 mV 2.2 2.5 210 2.7 V mV 0.907 0.925 1.1 0.943 V V A VOLTAGE REFERENCE (FB PIN) Feedback Voltage Feedback Over Voltage Threshold Feedback Bias Current VFB VFBOV IFB VFB=1V RDSONH RDSONL ISW=0.2A/0.7A ISW=-0.2A/-0.7A ILEAKH ILIMH ILIML VIN=18V,VEN=VSW=0V -0.1 0.1 MOSFET High-side Switch On-resistance(Note 3) Low-side Switch On-resistance(Note 3) 100 100 m m CURRENT LIMIT High-side Switch Leakage Current High-side Switch Current Limit Low-side Switch Current Limit 2.7 From Drain to Source 0.1 3.5 1.4 10 A A A 340 90 90 400 kHz kHz % % SWITCHING REGULATOR Oscillator Frequency Short Circuit Oscillator Frequency Max. Duty Cycle Min. Duty Cycle fOSC1 fOSC2 DMAX DMIN 280 VFB=0.85V VFB=1V 0 ERROR AMPLIFIER Error Amplifier Voltage Gain (Note 2) Error Amplifier Transconductance COMP to Current Sense Transconductance AEA GEA GCS 400 800 3.5 V/V A/V A/V TOTSD THYS 160 30 C C CSS=0.1F 15 ms VSS=0V 6 A THERMAL SHUTDOWN Thermal Shutdown (Note 2) Thermal Shutdown Hysteresis (Note 2) SOFT START (SS PIN) Soft-start Time (Note 2) Soft-start Current tSS Note 2: Not tested, guaranteed by design. Note 3: RDSON= May. 2012 VSW1 - VSW2 . ISW1 - ISW2 Rev. 1. 9 BCD Semiconductor Manufacturing Limited 5 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Typical Performance Characteristics TA=25C, VIN=12V, VOUT=3.3V, unless otherwise noted. 1.4 100 90 1.3 Quiescent Current (mA) Efficiency (%) 80 70 60 o VOUT=3.3V, L=10H, TA=25 C VIN=5V VIN=12V 50 40 30 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 1.2 1.1 1.0 0.9 -50 2.2 -25 0 25 50 75 100 125 150 o Case Temperature ( C) Output Current (A) Figure 4. Efficiency vs. Output Current Figure 5. Quiescent Current vs. Case Temperature 1.2 3.6 1.1 1.0 Output Voltage (V) Feedback Voltage (V) 3.5 0.9 0.8 0.7 0.6 -50 3.3 3.2 3.1 -25 0 25 50 75 100 125 3.0 0.0 150 o 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Output Current (A) Case Temperature ( C) Figure 6. Feedback Voltage vs. Case Temperature May. 2012 3.4 Figure 7. Output Voltage vs. Output Current Rev. 1. 9 BCD Semiconductor Manufacturing Limited 6 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Typical Performance Characteristics (Continued) TA=25C, VIN=12V, VOUT=3.3V, unless otherwise noted. 160 180 Low-side Switch On-resistance (m) High-side Switch On-resistance (m) 200 160 140 120 100 80 60 40 -60 -40 -20 0 20 40 60 80 100 120 140 120 100 80 60 40 -60 140 o -40 -20 0 20 40 60 80 100 120 140 o Case Temperature ( C) Case Temperature ( C) Figure 8. High-side Switch On-resistance vs. Case Temperature Figure 9. Low-side Switch On-resistance vs. Case Temperature VIN_AC 200mV/div VOUT_AC 100mV/div VOUT_AC 20mV/div IL 1A/div IOUT 1A/div VSW 10V/div Time Time 2s/div Figure 10. Output Ripple (IOUT=2A) May. 2012 200s/div Figure 11. Load Transient (IOUT =1A to 2A) Rev. 1. 9 BCD Semiconductor Manufacturing Limited 7 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Typical Performance Characteristics (Continued) TA=25C, VIN=12V, VOUT=3.3V, unless otherwise noted. VEN 2V/div VEN 2V/div VSS 2V/div VSS 2V/div VOUT 2V/div VOUT 2V/div IL 1A/div IL 1A/div Time 10ms/div Time Figure 12. Enable Turn on Characteristic (VIN=12V, VEN=3.3V, VOUT=3.3V, IL=2A) Figure 13. Enable Turn off Characteristic (VIN=12V, VEN=3.3V, VOUT=3.3V, IL=2A) VOUT 2V/div VOUT 2V/div IL 2A/div IL 2A/div Time Time 40s/div Figure 14. Short Circuit Protection (IOUT=0A) May. 2012 200s/div 40s/div Figure 15. Short Circuit Recovery (IOUT=0A) Rev. 1. 9 BCD Semiconductor Manufacturing Limited 8 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Typical Application Input Voltage=12V R4 100k 2 Output Voltage=3.3V L 10H C4 10nF 3 4 BS IN SW SS AP3502 1 EN COMP GND FB C11 10F/25V 8 C5 0.1F 7 C6 Optional 6 C3 4.7nF 5 R3 13k R2 10k C21 C22 22F/25V 22F/25V D1 Optional R1 26.1k Figure 16. Typical Application of AP3502 May. 2012 Rev. 1. 9 BCD Semiconductor Manufacturing Limited 9 Data Sheet 340kHz, 2A Synchronous DC-DC Buck Converter AP3502 Mechanical Dimensions SOIC-8 4.700(0.185) 5.100(0.201) 7 Unit: mm(inch) 0.320(0.013) 1.350(0.053) 1.750(0.069) 8 8 7 0.675(0.027) 0.725(0.029) D 5.800(0.228) 1.270(0.050) 6.200(0.244) TYP D 20:1 0.800(0.031) 0.300(0.012) R0.150(0.006) 0.100(0.004) 0.200(0.008) 0 8 1.000(0.039) 3.800(0.150) 4.000(0.157) 0.330(0.013) 0.190(0.007) 0.250(0.010) 1 5 0.510(0.020) 0.900(0.035) R0.150(0.006) 0.450(0.017) 0.800(0.031) Note: Eject hole, oriented hole and mold mark is optional. May. 2012 Rev. 1. 9 BCD Semiconductor Manufacturing Limited 10 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE IMPORTANT NOTICE BCD Semiconductor BCD Semiconductor Manufacturing Manufacturing Limited Limited reserves reserves the the right right to to make make changes changes without without further further notice notice to to any any products products or or specifispecifications herein. cations herein. BCD BCD Semiconductor Semiconductor Manufacturing Manufacturing Limited Limited does does not not assume assume any any responsibility responsibility for for use use of of any any its its products products for for any any particular purpose, particular purpose, nor nor does does BCD BCD Semiconductor Semiconductor Manufacturing Manufacturing Limited Limited assume assume any any liability liability arising arising out out of of the the application application or or use use of any of any its its products products or or circuits. circuits. 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