MP4423A – 3A, 36V, SYNCHRONOUS, STEP-DOWN CONVERTER

MP4423A Rev.1.0

www.MonolithicPower.com

12

4/22/2016

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PIN FUNCTIONS

Pin #

Name

Description

1

FB

Feedback. Connect FB to the tap of an external resistor divider from the output to GND to

set the output voltage. When the FB voltage is below 660mV, the frequency foldback

comparator lowers the oscillator frequency to prevent current limit runaway during a short-

circuit fault condition.

2

VCC

Bias supply. Decouple VCC with a 0.1μF to 0.22μF capacitor. Select a capacitor that

does not exceed 0.22μF.

3

EN/SYNC

Enable/synchronize. Drive EN/SYNC high to enable the MP4423A. Apply an external

clock to EN/SYNC to change the switching frequency.

4

BST

Bootstrap. A capacitor connected between SW and BST is required to form a floating

supply across the high-side switch driver. A 20Ω resistor placed between the SW and BST

cap is strongly recommended to reduce SW voltage spikes.

5

GND

System ground. GND is the reference ground of the regulated output voltage. GND

requires special consideration during PCB layout. For best results, connect GND with

copper traces and vias.

6

SW

Switch output. Connect using a wide PCB trace.

7

IN

Supply voltage. The MP4423A operates from a 4V to 36V input rail. C1 is required to

decouple the input rail. Connect using a wide PCB trace.

8

PG

Power good. The output of PG is an open drain and goes high if the output voltage

exceeds 90% of the nominal voltage.