MP2403 – 3A, 32V, 250kHz INTEGRATED SYNCHRONOUS STEP-DOWN CONVERTER

MP2403 Rev.1.0

www.MonolithicPower.com

4

4/20/2010

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PIN FUNCTIONS

Pin #

Name

Description

1

BS

High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel

MOSFET switch. Connect a 0.01μF or greater capacitor from SW to BS to power the

high side switch.

2

IN

Power Input. IN supplies the power to the IC, as well as the step-down converter

switches. Drive IN with a 4.6V to 32V power source. Bypass IN to GND with a suitably

large capacitor to eliminate noise on the input to the IC. See Input Capacitor.

3

SW

Power Switching Output. SW is the switching node that supplies power to the output.

Connect the output LC filter from SW to the output load. Note that a capacitor is

required from SW to BS to power the high-side switch.

4

GND,

Exposed Pad

Ground. The Exposed Pad and GND pin must be connected to the same ground plane.

5

FB

Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a

resistive voltage divider from the output voltage. The feedback threshold is 0.80V. See

Setting the Output Voltage

.

6

COMP

Compensation Node. COMP is used to compensate the regulation control loop.

Connect a series RC network from COMP to GND to compensate the regulation control

loop. In some cases, an additional capacitor from COMP to GND is required. See

Compensation Components.

7

EN

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to

turn on the regulator, drive it low to turn it off. Pull up with 100kΩ resistor to IN for

automatic startup.

8

SS

Soft-start Control Input. SS controls the soft-start period. Connect a capacitor from SS

to GND to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 15ms.

To disable the soft-start feature, leave SS unconnected.