MP2270 – 1.8A, 24V, 700KHz STEP-DOWN CONVERTER

MP2270 Rev. 1.1

www.MonolithicPower.com

4

4/16/2010

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PIN FUNCTIONS

Pin #

Name

Description

2, 4,

9, 7

NC

No Connect.

3

SW

Switch Output.

5

IN

Supply Voltage. The MP2270 operates from a +4.5V to +24V unregulated input. C1 is needed

to prevent large voltage spikes from appearing at the input.

6

EN

On/Off Control Input. Pull above 1.2V to turn the device on.

10

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.

8

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 D1 to C1 ground

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

pad must be connected to a ground plane for proper thermal operation.

1

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.