REFERENCE DESIGN IRDCiP2003A-C International Rectifier • 233 Kansas Street, El Segundo, CA 90245 USA IRDCiP2003A-C: 1MHz, 160A, Synchronous Buck Converter Using iP2003A Overview This reference design is capable of delivering up to a current of 160A with the enclosed heatsink attached at an ambient temperature of 60ºC with 400LFM or an ambient temperature of 45ºC with 200LFM of airflow. Performance graphs and waveforms are provided in figures 1–9. The figures and table in pages 5 – 8 are provided as a reference design to enable engineers to very quickly and easily design a 4-phase converter. Refer to the data sheet for the controller listed in the bill of materials in order to optimize this design to your specific requirements. A variety of other controllers may also be used, but the design will require layout and control circuit modifications. Demoboard Quick Start Guide Initial Settings: The output is set to 1.3V, but can be adjusted from 0.8V to 3.3V by changing the voltage divider values of R3 and R32 according to the following formula: R3 = R32 = (24.9k x 0.8) / (VOUT - 0.8) The switching frequency per phase is set to 1MHz with the frequency set resistor R4. This creates an effective output frequency of 4MHz. The graph in figure 11 shows the relationship between R4 and the switching frequency per phase. The frequency may be adjusted by changing R4 as indicated; however, extreme changes from the 1MHz set point may require redesigning the control loop and adjusting the values of input and output capacitors. Refer to the SOA graph in the iP2003A datasheet for maximum operating current at different conditions. Procedure for Connecting and Powering Up Demoboard: 1. Apply input voltage across (+12V) across VIN and PGND. 2. Apply load across VOUT pads and PGND pads. 3. Adjust load to desired level. See recommendations below. IRDCiP2003A-C Recommended Operating Conditions (refer to the iP2003A datasheet for maximum operating conditions) 1 Input voltage: 5V - 12V Output voltage: 0.8 - 3.3V Switching Freq: 1MHz per phase, 4MHz effective output frequency. Output current: This reference design is capable of delivering up to 160A with the enclosed heatsink attached, at an ambient temperature of 60ºC with 400LFM of airflow, or an ambient temperature of 45ºC with 200LFM of airflow. 1 Note: If Vin = 5V, then connect Vin to test point TP3 and Terminal T1 and remove jumper J1. Refer to schematic for details. Additionally, the threshold of the POR circuit should be adjusted to allow the supply to sequence properly. 12/03/04 IRDCiP2003A-C_ ____ 55.0 86% VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C 50.0 45.0 40.0 85% 84% 83% 82% 81% 80% Efficiency (%) 35.0 Power Loss (W) _____ 30.0 25.0 79% 78% VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C 77% 76% 20.0 75% 15.0 74% 73% 10.0 72% 5.0 71% 70% 0.0 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 Output Current (A) Output Current (A) Fig. 1: Power Loss vs. Current Fig. 2: Efficiency vs. Current Phase Margin = 61° Cross-Over Freq. = 106kHz VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 25°C Fig. 3: Bode Plot VIN = 12V, VOUT = 1.3V IOUT = 160A, fSW = 1MHz TA = 25°C VIN = 12V, VOUT = 1.3V IOUT = 160A, fSW = 1MHz TA = 25°C Ripple = 90mVp-p Ripple = 7.0mVp-p Fig. 4: Input Voltage Ripple Waveform www.irf.com Fig. 5: Output Voltage Ripple Waveform 2 160 _____________ __IRDCiP2003A-C 100.0% 99.8% Output Voltage Accuracy (%) 99.6% 99.4% 99.2% VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C 99.0% 98.8% 98.6% 98.4% 98.2% 98.0% 0 20 40 60 80 100 120 140 Output Current (A) Fig. 6: Output Voltage Accuracy vs. Current VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 25°C VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 25°C Ch. 1: VIN 2V/div Ch. 1: VIN 2V/div Ch. 2: VOUT 0.5V/div Ch. 2: VOUT 0.5V/div Fig. 7: Power Up Waveform Fig. 8: Power Down Waveform VIN = 12V VOUT = 1.3V fSW = 1MHz TA = 25°C Ch. 1: VOUT 1V/div Hiccups until short circuit is removed Short circuit at start-up Ch. 2: IOUT 50A/div Fig. 9: Short Circuit Condition Waveform 3 www.irf.com 160 IRDCiP2003A-C_ ____ *>120.0°C 120.0 100.0 VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 45°C Airflow = 200LFM Max 70.7°C _____ Board Temperature @ 1mm from edge of module: TPCB (U2): TPCB (U3): TPCB (U4): TPCB (U5): 80.0 60.0 83.4°C 82.7°C 82.3°C 79.2°C 40.0 Airflow direction *<21.3°C *>120.0°C 120.0 100.0 VIN = 12V VOUT = 1.3V IOUT = 160A fSW = 1MHz TA = 60°C Airflow = 400LFM Max 78.5°C Board Temperature @ 1mm from edge of module: TPCB (U2): 88.9°C TPCB (U3): 87.5°C TPCB (U4): 87.3°C TPCB (U5): 85.1°C 80.0 60.0 40.0 Airflow direction *<21.3°C Fig. 10: Thermal Images With Board and Heatsink Temperatures www.irf.com 4 _____________ __IRDCiP2003A-C Adjusting the Over-Current Limit R5, R7, R8, and R9 are the resistors used to adjust the over-current trip point. The trip point is a function of the controller and corresponds to the per phase output current indicated on the x-axis of Fig. 11. For example, selecting 3.65k resistors will set the trip point of each phase to 66A. (Note: Fig. 11 is based on iP2003A, TJ = 125°C. The trip point will be higher than expected if the reference board is cool and is being used for short circuit testing.) 3.7 3.6 3.5 3.4 3.3 RISEN (kΩ) 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 43 45 47 49 51 53 55 57 59 61 63 65 67 Over-Current Trip Point (per Phase) Fig. 11: RISEN vs. Current (per Phase) R4 (kΩ) 100 10 100 1000 Output Frequency (kHz) (per Phase) Fig. 12: R4 vs. Frequency (per Phase) 5 www.irf.com IRDCiP2003A-C_ ____ _____ Fig. 13: Component Placement Top Layer Heatsink Notes: 1) 2) 3) 4) Always use the supplied Berquist Gap PadTM A3000 thermal interface material with heatsink. Torque 5 x #2-56 machine screws to 15 +/-1 in-oz. The heatsink is optimized for 400 LFM with unconfined airflow. Performance will improve with more airflow or confined airflow. Airflow direction should be parallel to fins for maximum performance. Fig. 14: Heatsink Specification www.irf.com 6 10uF C27 Vin 3 Input Output LM1117DTX-5.0 U6 Adj/Gnd 1 2 Jumper J1 +5V C37 0.22uF 10uF PGND TP4 +5V TP3 0.22uF C38 2 3 0.22uF PRDY4 C28 2 3 CMPD3003A D2 ENA 1 1 40.2k1% R3 CMPD3003A D1 40.2k1% R32 24.9k1% R31 A C36 PRDY2 PRDY1 C35 0.22uF PRDY3 B TP2 24.9k1% R2 499 1% R6 6 110k1% R37 8 20k1% R4 7 2 PGOOD TP5 open C47 220pF C26 open R36 15pF C25 20k1% R1 11k1% R39 26.1k1% R38 ISL6558CB U1 GND FS/EN PGOOD VSEN Vin 560pF C1 3 301 R40 5 FB TP1 0 4 R35 3 COMP DROOP LM431 D3 1 ISEN4 PWM4 PWM3 ISEN3 PWM2 ISEN2 PWM1 ISEN1 VCC 15 16 9 10 12 11 13 14 1 +5V C2 open 0 +5V 0 1k1% R41 ENA IRLML6402 0 +5V R12 R11 0 R10 R13 R29 open R30 10uF Q1 +5V 10k1% R18 10k1% R17 10k1% R16 10k1% R19 +5V +5V +5V +5V open R28 open R26 open R24 open R22 PRDY4 ENA PRDY3 ENA PRDY2 ENA PRDY1 ENA +5V +5V +5V +5V 4 2 3 1 4 2 3 1 4 2 3 1 4 2 3 1 PRDY ENABLE PWM VDD U5 IP2003A PRDY ENABLE PWM VDD U4 IP2003A PRDY ENABLE PWM VDD U3 IP2003A PRDY ENABLE PWM VDD U2 IP2003A PGND PGND VSW VIN PGND PGND VSW VIN PGND PGND VSW VIN PGND PGND VSW VIN 5 7 6 8 5 7 6 8 5 7 6 8 5 7 6 8 VSW4 VSW3 VSW2 VSW1 C63 Vin C61 Vin C62 C60 C32 C31 C14 C11 C13 C10 C12 C9 C55 C53 C54 C52 C59 C58 C30 C8 C7 C6 C51 C50 Vin C57 C56 C33 C5 C4 C3 C49 C48 Vin 2.2uF VOUTS 1 2 2 3 2.2uF 2.2uF 2.2uF 2.2uF VSWS1 10uF 2.2uF 2.2uF 2.2uF VSWS2 10uF 10uF 10uF 10uF 9 10uF 10uF 10uF 10uF 10 10uF 10uF 10uF 10uF VSWS1 9 VSWS1 9 VSWS1 9 open 10uF 10uF 10uF VSWS2 10 VSWS2 10 VSWS2 10 open open open R9 3.65k1% R8 3.65k1% 3.65k1% R7 3.65k1% R5 VSW4 TP9 VSW3 TP8 VSW2 TP7 L1 L2 0.3uH 0.3uH L4 0.3uH L3 0.3uH VSW1 TP6 330uF C39 C67 C45 C22 C21 C66 C65 C44 C43 C20 C18 C19 C17 C64 C42 C16 PGNDS TP17 330uF C41 C15 330uF C40 VINS TP13 100uF 100uF 100uF open open 100uF 100uF 100uF 100uF open 100uF 100uF 100uF 100uF open open open open 100uF 7 open C46 10uF C34 0.1uF VOUT PGND T2 VIN T1 PGNDS PGNDS TP22 TP21 VOUTS VOUTS PGND T8 PGND T7 PGND T6 VOUT T5 VOUT T4 VOUT T3 _____________ __IRDCiP2003A-C Fig. 15: Reference Design Schematic www.irf.com IRDCiP2003A-C_ ____ _____ Table 1: Reference Design Bill of Materials Refer to the following application notes for detailed guidelines and suggestions when implementing iPOWIR Technology products: AN-1028: Recommended Design, Integration and Rework Guidelines for International Rectifier’s iPowIR Technology BGA and LGA and Packages This paper discusses optimization of the layout design for mounting iPowIR BGA and LGA packages on printed circuit boards, accounting for thermal and electrical performance and assembly considerations. Topics discussed includes PCB layout placement, and via interconnect suggestions, as well as soldering, pick and place, reflow, inspection, cleaning and reworking recommendations. AN-1030: Applying iPOWIR Products in Your Thermal Environment This paper explains how to use the Power Loss and SOA curves in the data sheet to validate if the operating conditions and thermal environment are within the Safe Operating Area of the iPOWIR product. AN-1047: Graphical solution for two branch heatsinking Safe Operating Area Detailed explanation of the dual axis SOA graph and how it is derived. Use of this design for any application should be fully verified by the customer. International Rectifier cannot guarantee suitability for your applications, and is not liable for any result of usage for such applications including, without limitation, personal or property damage or violation of third party intellectual property rights. IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 www.irf.com 8