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4470

High-Efficiency, Fast-Transient, 5A, 36V Synchronous, Step-Down Converter

Monolithic Power Systems 

MP4470/4470A–HIGH-EFFICIENCY, FAST-TRANSIENT, SYNCHRONOUS, STEP-DOWN CONVERTER

PIN FUNCTIONS

Pin #

Name

1

AGND

2

FREQ

3

FB

Description

Analog Ground.

Frequency Set (for CCM). The input voltage and the frequency-set resistor

connected to GND determine the ON period. Decouple with a 1nF capacitor.

Feedback. The tap of external resistor divider from the output to GND sets the

output voltage.

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

switch-mode regulator. When the EN pin goes HIGH, an internal current source

4

SS

(8.5µA) charges up the capacitor and the SS voltage slowly and smoothly ramps

up from 0 to VFB. When the EN pin goes LOW, the internal current source

discharges the capacitor and the SS voltage slowly ramps down.

5

EN

Enable. EN=1 to enable the MP4470/4470A. For automatic start-up, connect EN

pin to IN with a 100kΩ resistor. It includes an internal 1MΩ pull-down resistor.

6

PGOOD

Power Good Output. The output of this pin is an open drain and goes HIGH if the

output voltage exceeds 90% of the nominal voltage. There is delay of ~700µs from

FB ≥ 90% to PGOOD HIGH.

7

8, 19,

Exposed pads

21, 22, 23

9, 10, 17, 18,

Exposed pads

24, 25

11-16

20

BST

IN

SW

PGND

VCC

Bootstrap. Requires a 0.1µF-to-1µF capacitor connected between SW and BS pins

to form a floating supply across the high-side switch driver.

Supply Voltage. The MP4470/4470A operates from a 4.5V-to-36V input rail.

Requires CIN to decouple the input rail. Connect using wide PCB traces and

multiple vias.

Switch Output. Connect using wide PCB traces and multiple vias.

System Ground. This pin is the reference ground of the regulated output voltage.

For this reason care must be taken in PCB layout.

Internal Bias Supply. Decouple with a 1µF capacitor as close to the pin as

possible.

MP4470/4470A Rev. 1.1

www.MonolithicPower.com

7

8/26/2013

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2013 MPS. All Rights Reserved.

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