IRDCIP1203-A

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 *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 *