MP4459 – 1.5A, 4MHz, 36V STEP-DOWN CONVERTER

MP4459 Rev. 1.02

www.MonolithicPower.com

4

12/24/2013

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PIN FUNCTIONS

Pin #

Name

Description

1, 2

SW

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

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

current switch paths.

7

FREQ

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

switching frequency.

8, 9

VIN

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

the high-side switch. A decoupling capacitor to ground must e 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.