MP9447–HIGH-EFFICIENCY, FAST-TRANSIENT, SYNCHRONOUS, STEP-DOWN CONVERTER

MP9447 Rev. 1.2

www.MonolithicPower.com

8

1/5/2016

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

© 2016 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

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

3

FB

Feedback. The tap of 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 up the capacitor and the SS voltage slowly and smoothly ramps

discharges the capacitor and the SS voltage slowly ramps down.

5

EN

Enable. EN=1 to enable the MP9447. For automatic start-up, connect EN pin to IN

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

6

NC

No Connection. DO NOT CONNECT. The pin must be float.

7

BST

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.

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.

For this reason care must be taken in PCB layout.

20

VCC

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

possible.