MP38671 – 10A, 25V, 600KHz STEP-DOWN WITH SYNCHRONOUS GATE DRIVER

MP38671 Rev. 1.1

www.MonolithicPower.com

4

9/21/2011

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PIN FUNCTIONS

Pin #

Name

Description

1

FB

Feedback. An external resistor divider from the output to GND, tapped to the FB pin sets

the output voltage. To prevent current limit run away during a short circuit fault condition

the frequency foldback comparator lowers the oscillator frequency when the FB voltage is

below 250mV.

2

PG

The output of this pin is low if the output voltage is 10% less than the nominal voltage,

otherwise it is an open drain.

3

EN/SYNC On/Off Control and External Frequency Synchronization Input.

4, 5, 6

IN

Supply Voltage. The MP38671 operates from a +4.5V to +25V unregulated input. C1 is

needed to prevent large voltage spikes from appearing at the input.

7

N/C

No Connect.

8, 9, 10

SW

Switch Output.

11

BST

Bootstrap. This capacitor is needed to drive the power switch’s gate above the supply

voltage. It is connected between SW and BST pins to form a floating supply across the

power switch driver.

12

VCC

BG Driver Bias Supply. Decouple with a 1µF ceramic capacitor.

13

BG

Gate Driver Output. Connect this pin to the synchronous MOSFET Gate.

14

GND,

Exposed

pad

Ground. This pin is the voltage reference for the regulated output voltage. For this reason

care must be taken in its layout. This node should be placed outside of the M2 to C1

ground path to prevent switching current spikes from inducing voltage noise into the part.

The exposed pad and GND pin must be connected to the same ground plane.