International Rectifier • 233 Kansas Street, El Segundo, CA 90245 USA IRDCiP1203-A: 400kHz, 15A, Synchronous Buck Converter Using iP1203 Overview This reference design is capable of delivering a continuous current of 15A (with heatsink) or 12A (without heatsink) at an ambient temperature of 45ºC and airflow of 300LFM. Figures 1–20 provide performance graphs, thermal images, and waveforms. Figures 21–33 and Table 1 are provided to engineers as design references for implementing an iP1203 solution. The components installed on this demoboard were selected based on operating at an input voltage of 12V (+/-10%) and a switching frequency of 400kHz (+/-15%). Major changes from these set points may require optimizing the control loop and/or adjusting the values of input/output filters in order to meet the user’s specific application requirements. Refer to the iP1203 datasheet User Design Guidelines section for more information. Note: The 16-pin connector (CON1) is used only for production test purposes and should not be used for evaluation of this demoboard. (Photo shown without heatsink) Demoboard Quick Start Guide Initial Settings: VOUT is set to 1.8V, but can be adjusted from 1.0V to 3.3V by changing the values of R3 and R7 according to the following formula: R3 = R7 = (15k * 0.8) / (VOUT - 0.8) The switching frequency is set to 400kHz, but can be adjusted by changing the value of R10. The graph in Figure 22 shows the relationship between R10 and the switching frequency. Power Up Procedure: 1. Apply input voltage across VIN and PGND. 2. Apply load across VOUT pads and PGND pads. 3. Adjust load to desired level. See recommendations below. IRDCiP1203-A Recommended Operating Conditions (refer to the iP1203 datasheet for maximum operating conditions) Input voltage: 5.5V – 13.2V Output voltage: 1.0 – 3.3V Switching Freq: 400kHz Output current: This reference design is capable of delivering a continuous current of 15A (with heatsink) or 12A (without heatsink) at an ambient temperature of 45ºC and airflow of 300LFM. 11/30/04 5.5 5.0 Vo=1.0V Vo=1.3V Vo=1.8V Vo=2.5V Vo=3.3V 4.5 2.5 Power Loss (W) 3.0 Fig. 1: Power Loss vs. Output Current for Vin=5.5V Power Loss (W) 3.5 Fig. 2: Power Loss vs. Output Current for Vin=8.0V Power Loss (W) 4.0 Fig. 3: Power Loss vs. Output Current for Vin=12.0V 2.0 1.5 Conditions: Vin=5.5V Fsw=400kHz Ta=25ºC 1.0 0.5 0.0 0 1 2 3 4 5 6 7 8 9 10 Total Output Current (A) 11 12 13 14 15 5.5 5.0 Vo=1.0V Vo=1.3V Vo=1.8V Vo=2.5V Vo=3.3V 4.5 4.0 3.5 3.0 2.5 2.0 1.5 Conditions: Vin=8.0V Fsw=400kHz Ta=25ºC 1.0 0.5 0.0 0 1 2 3 4 5 6 7 8 9 10 Total Output Current (A) 11 12 13 14 15 5.5 5.0 Vo=1.0V Vo=1.3V Vo=1.8V Vo=2.5V Vo=3.3V 4.5 4.0 3.5 3.0 2.5 2.0 1.5 Conditions: Vin=12V Fsw=400kHz Ta=25ºC 1.0 0.5 0.0 0 1 2 3 www.irf.com 4 5 6 7 8 9 10 Total Output Current (A) 11 12 13 2 14 15 Vo=1.8V Vo=1.3V Vo=1.0V Conditions: Vin=5.5V Fsw=400kHz Ta=25ºC 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Efficiency (%) Vo=2.5V Fig. 4: Efficiency vs. Output Current for Vin=5.5V Efficiency (%) Vo=3.3V Fig. 5: Efficiency vs. Output Current for Vin=8.0V Efficiency (%) 96% 95% 94% 93% 92% 91% 90% 89% 88% 87% 86% 85% 84% 83% 82% 81% 80% 79% 78% 77% 76% 75% Fig. 6: Efficiency vs. Output Current for Vin=12.0V 15 Total Output Current (A) 96% 95% 94% 93% 92% 91% 90% 89% 88% 87% 86% 85% 84% 83% 82% 81% 80% 79% 78% 77% 76% 75% Vo=3.3V Vo=2.5V Vo=1.8V Vo=1.3V Vo=1.0V Conditions: Vin=8.0V Fsw=400kHz Ta=25ºC 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Output Current (A) Conditions: Vin=12V Fsw=400kHz Ta=25ºC 96% 95% 94% 93% 92% 91% 90% 89% 88% 87% 86% 85% 84% 83% 82% 81% 80% 79% 78% 77% 76% 75% Vo=3.3V Vo=2.5V Vo=1.8V Vo=1.3V Vo=1.0V 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Output Current (A) 3 www.irf.com 100.0% 99.9% Conditions: Vin=12V Vout=1.8V Fsw=400kHz 99.8% 99.7% 99.6% 99.5% 99.4% 99.3% 99.2% 99.1% 99.0% 0 1 2 3 4 5 6 7 8 9 10 11 12 Output Current (A) Fig. 7: Output Voltage Regulation vs. Current Phase-Margin = 59.3º Fc = 56.6kHz Conditions: Vin=12V Vout=1.8V Iout=15A Fsw=400kHz Gain-Margin = -18.9dB Fig. 8: Bode Plot www.irf.com 4 13 14 15 Fig. 9: Thermograph (With Heatsink) *>89.2°C Conditions: Vin = 12V Vout = 1.8V Iout = 15A Fsw = 400kHz Ambient Temp. = 45ºC Airflow = 300LFM Stabilizing Time = 15 min. 80.0 70.0 60.0 50.0 40.0 83.8 82.9 Max 83.2 30.0 Direction of Airflow *<24.1°C Fig. 10: Thermograph (No Heatsink) *>97.4°C Conditions: Vin = 12V Vout = 1.8V Iout = 12A Fsw = 400kHz Ambient Temp. = 45ºC Airflow = 300LFM Stabilizing Time = 15 min. 90.0 80.0 70.0 60.0 50.0 40.0 74.9 77.9 Max 92.9 30.0 20.0 *<19.8°C Direction of Airflow 5 www.irf.com Fig. 11: Power Up Sequence Conditions: Vin=12V Vout=1.8V Iout=15A Fsw=400kHz Conditions: Vin=12V Vout=1.8V Iout=15A Fsw=400kHz Fig. 12: Power Down Sequence For Closeup, see Fig. 13 Fig. 13: Power Down – Close Up Conditions: Vin=12V Vout=1.8V Iout=15A Fsw=400kHz www.irf.com 6 Fig. 14: Output Voltage Ripple Conditions: Vin=12V Vout=1.8V Iout=15A Fsw=400kHz Ripple = 11.6mVp-p Conditions: Vin=12V Vout=1.8V Fsw=400kHz Hiccups until short circuit is removed Fig. 15: Short Circuit Protection Conditions: Vin=12V Vout=1.8V Iout=15A Fsw=400kHz Fig. 16: Over-voltage Protection 7 www.irf.com + 41.0mV peak - 42.0mV peak Conditions: Vin=12V Vout=1.8V Fsw=400kHz Conditions: Vin=12V Vout=1.8V Fsw=400kHz Step-Up 50% to 75% Fig. 17: Iout Transient Step-Up 50% - 75% Step-Down 75% to 50% Fig. 18: Iout Transient Step-Down 75% - 50% + 81.0mV peak - 85.0mV peak Conditions: Vin=12V Vout=1.8V Fsw=400kHz Conditions: Vin=12V Vout=1.8V Fsw=400kHz Step-Up 50% to 100% Fig. 19: Iout Transient Step-Up 50% - 100% www.irf.com 8 Step-Down 100% to 50% Fig. 20: Iout Transient Step-Down 100% - 50% Adjusting the Over-Current Limit R9 is the resistor used to adjust the over-current trip point. The trip point corresponds to the peak inductor current indicated on the x-axis of Fig. 21. (Note: Fig. 21 is based on iP1203 TBLK = 125°C. The trip point will be higher than expected if the reference board is cool and is being used for short circuit testing.) 55 205 50 185 V o u t = 1.5V F sw = 300kH z L = 1u H 45 40 165 145 0 T BL K = 125 C 35 125 Vin=12 V 30 105 Vin=5.5V 25 85 20 65 15 45 10 25 5 5 6 8 10 12 14 16 18 20 22 24 O ver-Current T rip Point (Amps) Fig. 21: ROCSET vs. Over-Current Trip Point 50 45 Ω 40 35 30 25 20 15 200 220 240 260 280 300 320 340 360 380 Switching Frequency (kHz) Fig. 22: R10 vs. Frequency 9 www.irf.com 400 Fig. 23: Component Placement Top Layer Fig. 24: Component Placement Bottom Layer Fig. 25: Top Copper Layer Fig. 26: 1 Mid Copper Layer www.irf.com st 10 nd Fig. 27: 2 rd Mid Copper Layer Fig. 28: 3 Mid Copper Layer th Fig. 29: 4 Mid Copper Layer Fig. 30: Bottom Copper Layer 11 www.irf.com Fig. 31: Heatsink Photo Tolerances are ±0.38 (±0.015) Fig. 32: Mechanical Outline Drawing of Heatsink www.irf.com 12 Fig. 33: Reference Design Schematic J2 PGND J1 VIN TP2 PGND C1 10uF TP1 VIN C2 10uF C3 10uF C4 10uF R10 21.0k(400kHz) TP6 SYNC C6 0.1uF C5 2.2uF 10K R1 C7 100pF SS TP5 PGOOD PGNDS VINS 12 15 14 8 6 13 1 23 24 RT SYNC VREF SS Vcc_bypass PGOOD VIN VIN VINS U1 iP1203 PGND PGND PGND PGND PGND PGND PGND PGND 2 3 4 5 7 17 20 21 13 www.irf.com FBs CC FB Vsws Vsw Vsw OCSET 11 9 10 19 22 18 16 C11 100pF C8 33pF L1 1.2uH R7 12.1K 15K R6 C10 8200pF R4 10K TP7 VSW R9 37.4K VSW 15K R2 C12 100uF R3 12.1K 249 R5 C13 100uF C15 22uF C9 1000pF C14 100uF C16 22uF C17 22uF R8 0 TP3 VOUT TP4 PGND C18 0.1uF VOUTS J4 PGND J3 VOUT Quantity 4 1 2 3 3 2 1 1 1 1 1 2 1 2 2 1 1 1 7 1 Designator C1, C2, C3, C4 C10 C11, C7 C12, C13, C14 C15, C16, C17 C18, C6 C5 C8 C9 H1 L1 R1, R4 R10 R2, R6 R3, R7 R5 R8 R9 PGND, PGND, PGOOD, SYNC, VIN, VOUT, VSW U1 Type 1 Type 2 capacitor X7R capacitor X7R capacitor NPO capacitor X5R capacitor X5R capacitor X7R capacitor X5R capacitor NPO capacitor COG hardware heatsink inductor metal composite resistor thick film resistor thick film resistor thick film resistor thick film resistor thick film resistor carbon film resistor thick film Value 1 10.0uF 8200pF 100pF 100uF 22.0uF 0.100uF 2.20uF 33.0pF 1000pF 16 fins 1.20uH 10.0K 21.0K 15.0K 12.1K 249 0 37.4K Value 2 16V 50V 50V 6.3V 6.3V 16V 6.3V 50V 100V 0.400" 22A 1/10W 1/10W 1/10W 1/10W 1/10W 1/16W 1/10W hardware test point 90 mils 112 x 150 mils iP1203 LGA unit - - Tolerance Package Manufacturer Manufacturer P/N 10% 1206 TDK C3216X7R1C106KT 10% 0603 KOA X7R0603HTTD822K 5% 0603 Phycomp 0603CG101J9B20 20% 1210 TDK C3225X5R0J107M 20% 1206 TDK C3216X5R0J226M 10% 0603 MuRata GRM188R71C104KA01D 10% 0603 Murata GRM39X5R225K6.3 5% 0603 KOA NPO0603HTTD330J 5% 0603 TDK C1608COG2A102J 10.6mm x 10.6mm Aavid/ Thermalloy NP974686 REV 1 20% SMT Delta Electronics MPL104-1R2IR 1% 0603 KOA RK73H1J1002F 1% 0603 KOA RK73H1JLTD2102F 1% 0603 KOA RK73H1J1502F 1% 0603 KOA RK73H1JLTD1212F 1% 0603 KOA RK73H1JLTD2490F <50m 0603 ROHM MCR03EZHJ000 1% 0603 KOA RK73H1J3742F - SMT Keystone 5016 - 9mm x 9mm IRF - 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 14