MP9151

– 20V, 4A SYNCHRONOUS STEP-DOWN CONVERTER

MP9151 Rev. 1.0

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4

3/20/2013

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PIN FUNCTIONS

QFN 2X3mm

Pin #

Name Description

1, 12,

13, 14

GND

Ground. Connect these pins with larger copper areas to the negative terminals of the

input and output capacitors. Connect exposed pad to GND plane for proper thermal

performance.

2, 11

SW

Switch Output. Use wide PCB traces and multiple vias to make the connection.

3, Center Pad

IN

Supply Voltage. The MP9151 operates from a +4.5V to +20V input rail. C1 is needed to

decouple the input rail. Use wide PCB traces and multiple vias to make the connection.

4

EN

Enable. EN=1 to enable the MP9151. The EN pin sources 2.3

μA current. Place a

capacitor from EN to GND for delayed start-up.

5

PG

Power Good Indicator. An external pull-up resistor is needed across PG pin and VCC.

6

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 100mV.

7

SS

Soft Start. Connect an external capacitor to program the soft start time for the switch

mode regulator.

8

FREQ

Switching Frequency Program Input. Connect a resistor from this pin to ground to set

the switching frequency.

9

VCC

Bias Supply. Decouple with 1µF capacitor.

10

BST

Bootstrap. A capacitor connected between SW and BST pins is required to form a

floating supply across the high-side switch driver.