Technical Note

11/20

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2010.08 - Rev.A

© 2010 ROHM Co., Ltd. All rights reserved.

BD8119FM-M

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Procedure for external components selection

Follow the steps as shown below for selecting the external components

1.

Work out IL_MAX from the operating conditions.

2.

Select the value of RSC such that IOCP > IL_MAX

3.

Select the value of L such that 0.05/µs < VOUT / L < 0.3V/ µs

4.

Select coil, schottky diodes, MOSFET and RCS which meet with the ratings

5.

Select the output capacitor which meets with the ripple voltage requirements

6.

Select the input capacitor

7.

Work on with the compensation circuit

8.

Work on with the Over-Voltage Protection (OVP) setting

9.

Work on with the soft-start setting

10.

Verify experimentally

Feedback the value of L