07/22/03

IRDCiP2002-C: 1MHz, 120A, 4-phase Synchronous Buck

Converter using iP2002

Overview

This reference design is capable of delivering up to 120A at an

ambient temperature of 45°C if the enclosed heatsink is attached

and 250LFM of airflow is provided. Performance graphs and

waveforms are provided in figures 1 - 9. The figures and table in

pages 4 - 7 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.

IRDCiP2002-C

International Rectifier

iP2002 Recommended Operating Conditions

(refer to the iP2002 datasheet for maximum operating conditions)

Input voltage:

6.5 - 12V

Output voltage:

0.8 - 3.3V

Switching Freq:

1MHz per phase, 4MHz effective output frequency.

Output current:

The reference design is capable of delivering up to 120A at an ambient temperature of 45°C if the

enclosed heatsink is attached and 250LFM of airflow is provided. With a heatsink and no airflow, the

reference board is capable of delivering 110A at 25°C ambient. With 250LFM and no heatsink, the

reference board is capable of delivering 100A at 25°C ambient.

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 values of R3 and R32 according to

the following formula:

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 iP2002 datasheet for maximum operating current at different conditions.

Procedure for Connecting and Powering Up Demoboard:

1. Apply input voltage (+12V) across VIN and PGND

2. Apply load across VOUT pads and PGND pads

3. Adjust load to desired level. See recommendations below.