MP8864

– SYNCHRONOUS STEP-DOWN CONVERTER

MP8864 Rev. 1.02

www.MonolithicPower.com

12

1/18/2018

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PIN FUNCTIONS

Pin #

Name

Description

1

VIN

Supply voltage. The MP8864 operates from a 4.5 V to 21 V input rail. VIN requires a

ceramic capacitor to decouple the input rail. Connect VIN using a wide PCB trace.

2, 8

PGND

System ground. PGND is the reference ground of the regulated output voltage. PGND

requires special consideration during PCB layout

(see the “PCB Layout Guidelines”

section on page 24). Connect PGND to GND with copper traces and vias.

3

EN/SYNC

EN high to enable the MP8864. EN/SYNC has an internal 1

MΩ pull-down resistor to

ground.

4

PG

Power good. PG is an open-drain structure.

5

SDA

6

SCL

7

ADD

to ground sets an additional, different address.

9

SW

Switch output. Connect SW using a wide PCB trace.

10

BST

Bootstrap. BST requires a capacitor between SW and BST to form a floating supply

across the high-side switch driver.

11

VOUT

Sense input of output voltage in I

12

FB

Feedback. Connect FB to the tap of an external resistor divider from the output to GND to

set the output voltage in the FB control loop. Connecting FB to VCC sets the default

output voltage at 0.9 V.

13

SS

Soft-start. Connect a capacitor from SS to ground to set the soft-start time.

14

VCC

Internal 5V LDO regulator output. Decouple with a 0.22 µF capacitor.

15

AGND

Signal ground. AGND is not connected internally to system ground. Ensure AGND is

connected to system ground in the PCB layout.