MP9942 – 36V, 2A SYNCHRONOUS STEP-DOWN CONVERTER

MP9942 Rev.1.1

www.MonolithicPower.com

6

8/7/2017

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PIN FUNCTIONS

Package

Pin #

Name

Description

1

PG

Power Good. The output of this pin is an open drain and goes high if the output voltage

exceeds 90% of the nominal voltage.

2

IN

Supply Voltage. The MP9942 operates from a 4V to 36V input rail. Requires C1 to

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

3

SW

Switch Output. Connect with a wide PCB trace.

4

GND

System Ground. This pin is the reference ground of the regulated output voltage, and PCB

layout requires special care. For best results, connect to GND with copper traces and vias.

5

BST

Bootstrap. Requires a capacitor connected between SW and BST pins to form a floating

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

is strongly recommended to reduce SW spike voltage.

6

EN/SYNC

Enable/Synchronize. EN/SYNC high to enable the MP9942. Apply an external clock to the

EN/SYNC pin to change the switching frequency.

7

VCC

Bias Supply. Decouple with 0.1μF-to-0.22μF capacitor. Select a capacitor that does not

exceed 0.22μF

8

FB

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

the output voltage. The frequency fold-back comparator lowers the oscillator frequency

when the FB voltage is below 660mV to prevent current limit runaway during a short-circuit

fault condition.