MP4559 – 1.5A, 2MHz, 55V STEP-DOWN CONVERTER

MP4559 Rev. 1.01

www.MonolithicPower.com

4

12/23/2013

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PIN FUNCTIONS

QFN

Pin #

SOIC8

Pin #

Name

Description

1, 2

1

SW

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

3

2

EN

Enable Input. Pull this pin below the specified threshold to shutdown the chip. Pull it

up above the specified threshold or leaving it floating to enable the chip.

4

3

COMP

Compensation. Output of the GM error amplifier. Control loop frequency

compensation is applied to this pin.

5

4

FB

Feedback. Input to the error amplifier. Sets the regulator voltage by comparing the

tap of an external resistive divider connected between the output and GND to the

internal +0.8V reference.

6

5

GND,

Exposed

pad

Ground. Connect as close as possible to the output capacitor and avoid the high-

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

performance.

7

6

FREQ

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

the switching frequency.

8, 9

7

VIN

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

regulators, and the high-side switch. Place a decoupling capacitor to ground close to

this pin to minimize switching spikes.

10

8

BST

Bootstrap. Positive power supply for the internal floating high-side MOSFET driver.

Connect a bypass capacitor between this pin and SW pin.