MP4561 – 1.5A, 2MHz, 55V STEP-DOWN CONVERTER

MP4561 Rev. 1.0

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4

11/5/2012

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PIN FUNCTIONS

QFN

Pin #

Name

Description

1, 2

SW

ground is required. The rectifier must be close to the SW pins to reduce switching spikes.

3

EN

Enable Input. Pulling this pin below the specified threshold shuts the chip down. Pulling it

up above the specified threshold or leaving it floating enables the chip.

4

COMP

Compensation. This node is the output of the GM error amplifier. Control loop frequency

compensation is applied to this pin.

5

FB

Feedback. This is the input to the error amplifier. An external resistive divider connected

between the output and GND is compared to the internal +0.8V reference to set the

regulation voltage.

6

GND,

Exposed Pad

Ground. It should be connected as close as possible to the output capacitor avoiding the

high current switch paths. Connect exposed pad to GND plane for optimal thermal

performance.

7

FREQ

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

switching frequency.

8

SS

Soft start programming mode. Connect a capacitor between SS and GND to set the soft

start time.

9

VIN

Input Supply. This supplies power to all the internal control circuitry, both BST regulators

and the high-side switch. A decoupling capacitor to ground must be placed close to this

pin to minimize switching spikes.

10

BST

Bootstrap. This is the positive power supply for the internal floating high-side MOSFET

driver. Connect a bypass capacitor between this pin and SW pin.