MP4473–HIGH-EFFICIENCY, FAST-TRANSIENT, SYNCHRONOUS, STEP-DOWN CONVERTER

MP4473 Rev. 1.0

www.MonolithicPower.com

10

12/15/2014

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

© 2014 MPS. All Rights Reserved.

PIN FUNCTIONS

Pin #

Name

Description

1

AGND

Analog Ground.

2

FREQ

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

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

3

FB

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

output voltage.

4

SS

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

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

the capacitor, and the SS voltage slowly ramps down.

5

EN

Enable. EN=1 to enable the MP4473. 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

BST

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

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

8, 19,

Exposed pads

21, 22, 23

IN

to decouple the input rail. Connect using wide PCB traces and multiple vias.

9, 10, 17, 18,

Exposed pads

24, 25

SW

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

11-16

PGND

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

*Care must be taken in PCB layout.

20

Vcc

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

possible.