MP28367 – 1A, 21V, 1.4MHz STEP-DOWN CONVERTER IN A TSOT23-6

MP28367 Rev. 0.9

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3

12/13/2007

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TM

PIN FUNCTIONS

Pin #

Name Description

1

BST

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

is connected between SW and BS pins to form a floating supply across the power switch driver.

2

GND

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.

3

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.

4

EN

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

5

IN

Supply Voltage. The MP28367 operates from a +6V to +21V unregulated input. C1 is needed to

prevent large voltage spikes from appearing at the input.

6

SW

Switch Output.