MP4558

– 1A, 2MHz, 55V STEP-DOWN CONVERTER

MP4558 Rev. 1.01

www.MonolithicPower.com

4

10/28/2013

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PIN FUNCTIONS

SOIC8

Pin #

QFN10

Pin#

Name

Description

1

1, 2

SW

to ground. Place the rectifier close to the SW pins to reduce switching spikes.

2

3

EN

Enable Input. Pull this pin below the specified threshold to shut the chip down. Pull

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

3

4

COMP

Compensation.

GM

error

amplifier

output.

Apply

control-loop

frequency

compensation to this pin.

4

5

FB

Feedback. Input to the error amplifier. Connect an external resistive divider

between the output and GND: Compare to the internal +0.8V reference to set the

regulation voltage.

5

6

GND,

Exposed

pad

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

current switching paths. Connect the exposed pad to GND plane for optimal

thermal performance.

6

7

FREQ

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

set the switching frequency.

7

8, 9

VIN

Input Supply. 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.

8

10

BST

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

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