A Product Line of Diodes Incorporated PAM2319 DUAL HIGH-EFFICIENCY PWM STEP-DOWN DC-DC CONVERTER Description Pin Assignments The PAM2319 is a dual step-down current-mode, DC-DC converter. At heavy load, the constantf requency PWM control performs excellent stability and transient response. To ensure the longest battery life in portable applications, the PAM2319 provides a powersaving Pulse-Skipping Modulation (PSM) mode to reduce quiescent current under light load operation. The PAM2319 supports a range of input voltages from 2.7V to 5.5V, allowing the use of a single Li+/Li-polymer cell, multiple Alkaline/NiMH cell, USB, and other standard power sources. The dual output voltages are adjustable from 1.0V to 3.3V. Both channels employ internal power switch and synchronous rectifier to minimize external part count and realize high efficiency. During shutdown, the input is disconnected from the output and the shutdown current is less than 0.1A. Other key features include under-voltage lockout, soft-start, short circuit protection and thermal shutdown. Features Supply Voltage: 2.7V to 5.5V Output Voltage: Applications Portable Electronics Vo1 ADJ/1000mA Personal Information Appliances Vo2 ADJ/2000mA Wireless and DSL Modems Low Quiescent Current: Channel 1: 40A; Channel 2: 55A High Efficiency: Switching Frequency: 3MHz(Channel 1) Internal Synchronous Rectifier Soft Start Under-Voltage Lockout Short Circuit Protection Thermal Shutdown Small W-DFN3X3-12L Pb-Free/Halogen Free Package RoHS/REACH Compliant 2.5MHz(Channel 2) PAM2319 Document number: DSxxxxx Rev. 1 - 1 1 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Typical Applications Circuit Figure 1. Adjustable Voltage Regulator Pin Descriptions Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 -- W-DFN3x3-12L Pin Name FB2 VIN2 AGND2 VIN1 PGND1 SW1 FB1 AGND1 EN1 EN2 PGND2 SW2 Exposed Pad Function Channel 2 feedback pin internally set to 0.6V. Input voltage pin of channel 2. Signal ground of channel 2 for small signal components. Input voltage pin of channel 1. Main power ground pin of channel 1 Channel 1 switching pin. The drains of the internal main and synchronous power MOSFET. Channel 1 feedback pin internally set to 0.6V. Signal ground of channel 1 for small signal components. Enable control input. Pull logic high to enable Vo1. Pull logic low to disable. Enable control input. Pull logic high to enable Vo2. Pull logic low to disable. Main power ground pin of channel 2. Channel 2 switching pin. The drains of the internal main and synchronous power MOSFET. Connect to GND PAM2319 Document number: DSxxxxx Rev. 1 - 1 2 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Functional Block Diagram Note: 1. The diagram above just shows one channel. Absolute Maximum Ratings (@TA = +25C, unless otherwise specified.) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Parameter Input Voltage EN1, FB1, SW1, EN2, FB2 and SW2 Pin Voltage Maximum Junction Temperature Storage Temperature Range Soldering Temperature Rating -0.3 to 6.5 Unit V -0.3 to (VIN +0.3) 150 -65 to +150 260, 10sec C C C V Recommended Operating Conditions (@TA = +25C, unless otherwise specified.) Parameter Supply Voltage Ambient Temperature Range Junction Temperature Range Rating 2.7 to 5.5 -40 to +85 -40 to +1255 Unit V C Thermal Information Parameter Symbol Package Max Thermal Resistance (Junction to Ambient) JA W-DFN3x3-12L 60 Thermal Resistance (Junction to Case) JC W-DFN3x3-12L 8.5 PAM2319 Document number: DSxxxxx Rev. 1 - 1 3 of 12 www.diodes.com Unit C/W November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Electrical Characteristics (@TA = +25C, VIN = 3.3V, VO = 1.8V, CIN = 10F, CO = 10F, L = 1H, unless otherwise specified.) Channel 1 Parameter Input Voltage Range UVLO Threshold Symbol Test Conditions VUVLO Reference Voltage Line Regulation Typ 2.4 VIN Rising Hysteresis VIN Falling Regulated Feedback Voltage Min 2.7 VIN V 2.5 V 240 mV V 0.600 0.612 0.3 VFB Regulated Output Voltage Accuracy VO IO = 100mA Peak Inductor Current IPK VO = 90% 1.5 0.2 Output Voltage Line Regulation LNR VIN = 2.7V to 5V, IO = 10mA Output Voltage Load Regulation LDR IO = 1mA to 1000mA Units 5.5 1.8 0.588 VFB Max -3 -2 V %/V +3 % 0.5 %/V +2 % A Quiescent Current IQ No Load 40 80 A Shutdown Current ISD VEN = 0V 0.1 1 A Oscillator Frequency fOSC Drain-Source On-State Resisitance SW Leakage Current Efficiency RDS(ON) ITH EN Threshold High VEH EN Threshold Low VEL EN Leakage Current IEN Over Temperature Protection OTP Hysteresis PAM2319 Document number: DSxxxxx Rev. 1 - 1 3 1 0.35 0.35 0.01 ILSW PSM Threshold Soft-Start VO = 100% VFB = 0V or VO =0V P MOSFET N MOSFET TON OTP OTH MHz MHz 0.45 0.45 1 A Output1, IO = 500mA, VIN = 3.3V 84 % VIN = 3.3V 100 mA 1.5 V 0.3 From EN1 to Output 4 of 12 www.diodes.com V 0.01 A 2 ms 150 30 C C November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Electrical Characteristics (@TA = +25C, VIN = 3.3V, VO = 1.2V, CIN = 10F, CO = 10F, L = 1H, unless otherwise specified.) Channel 2 Parameter Input Voltage Range UVLO Threshold Symbol Test Conditions VUVLO Reference Voltage Line Regulation VO IO = 100mA IPK VO = 90% Output Voltage Line Regulation LNR VIN = 2.7V to 5V, IO = 10mA Output Voltage Load Regulation LDR IO = 1mA to 1000mA IQ V 2.7 V mV V 0.600 0.612 0.3 Peak Inductor Current -3 V %/V +3 % 0.2 0.5 %/V +2 % 55 100 A 1.0 3 -2 No Load Units 5.5 250 0.588 VFB Max 12 VFB Regulated Output Voltage Accuracy Quiescent Current Typ 2.6 VIN Rising Hysteresis VIN Falling Regulated Feedback Voltage Min 2.7 VIN A Shutdown Current ISD VEN = 0V 0.1 Oscillator Frequency fOSC VO = 100% P MOSFET N MOSFET 2.5 MHz 0.11 0.85 0.01 1 A 450 mA Drain-Source On-State Resisitance SW Leakage Current Efficiency RDS(ON) ILSW PSM Threshold ITH EN Threshold High VEH EN Threshold Low VEL EN Leakage Current IEN Soft-Start Over Temperature Protection OTP Hysteresis PAM2319 Document number: DSxxxxx Rev. 1 - 1 TON OTP OTH Output1, IO = 500mA, VIN = 3.3V 87 VIN = 3.3V 250 % 1.5 V 0.3 From EN1 to Output 5 of 12 www.diodes.com A V 0.01 A 250 ms 150 30 C C November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Typical Performance Characteristics (@TA = +25C, VO = 1.8V CIN = 10F, CO = 10F, L = 1H, unless otherwise specified.) Channel 1 PAM2319 Document number: DSxxxxx Rev. 1 - 1 6 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Typical Performance Characteristics (cont.) (@TA = +25C, VO = 1.2V CIN = 10F, CO = 10F, L = 1H, unless otherwise specified.) Channel 2 PAM2319 Document number: DSxxxxx Rev. 1 - 1 7 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Application Information The basic PAM2319 application circuit is shown in Page 2. External component selection is determined by the load requirement, selecting L first and then CIN and COUT. Inductor Selection For most applications, the value of the inductor will fall in the range of 0.47H to 2H. Its value is chosen based on the desired ripple current and efficiency. Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher VIN or VOUT also increases the ripple current as shown in equation. For channel 1, 1A reasonable starting point for setting ripple current is IL = 400mA (40% of 1A) and for channel 2, 2A setting ripple current is 800mA. IL 1 V OUT VIN 1 Equation (1) f L VOUT The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. Thus, a 4.2A rated inductor should be enough for most applications (3A + 1.2A). For better efficiency, choose a low DC-resistance inductor. VO L 1.2V 1.5V 1.8V 2.5V 3.3V 1.2H 1.5H 2.2H 2.2H 2.2H CIN and COUT Selection In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: CIN required IRMS IOMAX VOUT VIN VOUT 1/ 2 VIN This formula has a maximum at VIN = 2VOUT, where IRMS =IOUT /2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer's ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Consult the manufacturer if there is any question. The selection of COUT is driven by the required effective series resistance (ESR). Typically, once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE (P-P) requirement. The output ripple VOUT is determined by: V OUT IL ESR 1 / 8f COUT Where f = operating frequency, COUT = output capacitance and IL = ripple current in the inductor. For a fixed output voltage, the output ripple is highest at maximum input voltage since IL increases with input voltage. Using Ceramic Input and Output Capacitors Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. Using ceramic capacitors can achieve very low output ripple and small circuit size. When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formul ations. These dielectrics have the best temperature and voltage characteristics of all the ceramics for a given value and size. Thermal Consideration Thermal protection limits power dissipation in the PAM2319. When the junction temperature exceeds +150C, the OTP (Over Temperature Protection) starts the thermal shutdown and turns the pass transistor off. The pass transistor resumes operation after the junction temperature drops below +120C. For continuous operation, the junction temperature should be maintained below +125C. The power dissipation is defined as: PD IO 2 V O RDS(ON)H VIN V O RDS( ON)L VIN tSW FS IO IQ VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses. PAM2319 Document number: DSxxxxx Rev. 1 - 1 8 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Application Information (cont.) For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PD IO 2 RDS(ON)H IQ VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surrounding airflow and temperature difference between junction and ambient. The maximum power dissipation can be calculated by the following formula: PD T J(MAX ) T A JA Where TJ(max) is the maximum allowable junction temperature +125C. TA is the ambient temperature and JA is the thermal resistance from the junction to the ambient. Based on the standard JEDEC for a two layers thermal test board, the thermal resistance JA of WDFN3x3 is 60C/W. The maximum power dissipation at TA = +25C can be calculated by following formula: PD = (125C - 25C) /60C/W = 1.67W Setting the Output Voltage The internal reference is 0.6V (Typical). The output voltage is calculated as below: The output voltage is given by Table 1. R1 V O 0 .6 x 1 R 2 Table 1: Resistor selection for output voltage setting. VO R1 R2 1.2V 1.5V 1.8V 2.5V 3.3V 150k 150k 300k 380k 680k 150k 100k 150k 120k 150k Pulse Skipping Mode (PSM) Description When load current decreases, the peak switch current in Power-PMOS will be lower than skip current threshold and the device will enter into Pulse Skipping Mode. In this mode, the device has two states, working state and idle state. First, the device enters into working state controlled by internal error amplifier.When the feedback voltage gets higher than internal reference voltage, the device will enter into low IQ idle state with most of internal blocks disabled. The output voltage will be reduced by loading or leakage current. When the feedback voltage gets lower than the internal reference voltage, the convertor will start a working state again. 100% Duty Cycle Operation As the input voltage approaches the output voltage, the converter turns the P-Channel transistor continuously on. In this mode the output voltage is equal to the input voltage minus the voltage drop across the P-Channel transistor: V OUT VIN ILOAD RDSON RL where RDS(ON) = P-Channel switch ON resistance, ILOAD = Output Current, RL = Inductor DC Resistance UVLO and Soft-Start The reference and the circuit remain reset until the VIN crosses its UVLO threshold. The PAM2319 has an internal soft-start circuit that limits the in-rush current during start-up. This prevents possible voltage drops of the input voltage and eliminates the output voltage overshoot. Thermal Shutdown When the die temperature exceeds +150C, a reset occurs and the reset remains until the temperature decrease to +120C, at which time the circuit can be restarted. PAM2319 Document number: DSxxxxx Rev. 1 - 1 9 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Application Information (cont.) Short Circuit Protection Channel 1: The swich peak current is limited cycle-by-cycle to a typical vaule in the event of an output voltage short circuit. The device operates with a frequency of 1MHz and minimum duty clycle. Therefore the average input current is typical 350mA (VIN = 3.3V). Channel 2: When the converter output is shorted or the device is overloaded, each high-side MOSFET current-limit event (3A typ) turns off the high-side MOSFET and turns on the low-side MOSFET. An internal counter is used to count the each current-limit event. The counter is reset after consecutive high-side MOSFETs turn on without reaching current limit. If the current-limit condition persists, the counter fills up. The control logic then stops both high-side and lowside MOSFETs and waits for a hiccup period, before attemping a new soft-start sequence. The counter bits is decided by VFB voltage. If VFB 0 2, the counter is 3-bit counter; if VFB > 0.2 the counter is 6-bit counter. The typical hicuup made duty cycle is 1.7%. The hiccup mode is disable during soft-start time. PCB Layout Check List When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the PAM2319. Check the following in your layout: 1. The input capacitor should be close to IC as close as possible. 2. Minimize the switching loop area to avoid excessive switching noise. 3. Two parts GND should be separately layout to avoid disturbing by each other. 4. Must put a small decoupling capacitor between Vin2 Pin and AGND2 Pin. 5. Vo2 output capacitor should be close to output connector to minimize PCB t race resistance affect on ripple voltage. Recommend use two output capacitor, one close to inductor and IC, another close to output connector. 6. PGND1 Pin should not directly connect to the thermal pad (PGND), it should connect to input capacitor GND then to other GND. 7. AGND should connect to PGND at input capacitor GND. 8. For the good thermal dissipation, PAM2316 has a heat dissipate pad in the bottom side, it should be soldered to PCB surface. For the copper area can't be large in the component side, so we can use multiple vias connect to other side of the PCB. 9. Avoid using vias in the high-current paths. If vias are unavoidable, use multiple vias in parallel to reduce resistance and inductance. Ordering Information Part Number PAM2319AYAA PAM2319 Document number: DSxxxxx Rev. 1 - 1 Part Marking BNAA XXXYW Package Type Standard Package W-DFN3x3-12L 3000 Units/Tape & Reel 10 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 Marking Information Package Outline Dimensions (All dimensions in mm.) W-DFN3x3-12 PAM2319 Document number: DSxxxxx Rev. 1 - 1 11 of 12 www.diodes.com November 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM2319 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). 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Copyright (c) 2012, Diodes Incorporated www.diodes.com PAM2319 Document number: DSxxxxx Rev. 1 - 1 12 of 12 www.diodes.com November 2012 (c) Diodes Incorporated Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Diodes Incorporated: PAM2319AYAA