MP2325

– 24V, 3A SYNC STEP DOWN CONVERTER

MP2325 Rev. 1.0

www.MonolithicPower.com

7

12/4/2013

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PIN FUNCTIONS

Package

Pin #

Name

Description

1

PG

Power Good Output. The output of this pin is an open drain. It

’s pulled up to Vcc by

external resistor when the output voltage exceeds 90% of the normal voltage. There is a

40

μs delay between FB≥90% to the PG pin goes high.

2

IN

Supply Voltage. The IN pin supplies power for internal MOSFET and regulator. The

MP2325 operates from a +4.5V to +24V input rail. Requires a low-ESR, and low

inductance capacitor (C1) to decouple the input rail. Place the input capacitor very close to

this pin and connect it with wide PCB traces and multiple vias.

3

SW

Switch Output. Connect to the inductor and bootstrap capacitor. This pin is driven up to

VIN by the high-side switch during the PWM duty cycle ON time. The inductor current

drives the SW pin negative during the OFF time. The ON resistance of the low-side switch

and the internal body diode fixes the negative voltage. Connect using wide PCB traces and

multiple vias.

4

GND

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

For this reason care must be taken in PCB layout. Suggested to be connected to GND with

copper and vias.

5

BST

Bootstrap. A capacitor and a 20

Ω resistor connected between SW and BST pins are

required to form a floating supply across the high-side switch driver.

6

EN/SYNC

EN=1 to enable the MP2325. External clock can be applied to EN pin for changing

switching frequency. For automatic start-up,

connect EN pin to VIN with a 100kΩ resistor.

7

VCC

Bias Supply. Decouple with 0.1

μF-0.22μF cap. And the capacitance should be no more

than 0.22

μF

8

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 fold-back comparator lowers the oscillator frequency when the FB voltage is

below 400mV.