Preliminary Datasheet

LP28400

LP28400-00 Version 1.0 May.-2013

www.lowpowersemi.com

Page 3 of 17

Pin Description

PIN

PIN

NO.

DESCRIPTION

CMS

1

Connect to common source of Nch ACFET and reverse blocking Nch RBFET. Place 4K resistor from

CMS pin to the common source of ACFET and RBFET to control the turn-on speed.

ACDRV

2

AC adapter to system switch driver output.

AVCC

3

IC power supply of internal bias. Put 1uF MLCC from AVCC to AGND. Add 10Ω resistor to filter the noise

of power line.

VREF

4

3.3V reference output. A 1uF MLCC is placed from VREF to GND to make it stable.

TS

5

NTC resistor connection.

ISET

6

Fast charge current set pin.

CELL

7

Cell selection pin. Set CELL pin LOW or floating for 2-cell, HIGH for 1-cell.

STAT

8

Open-Drain Charge Status Output.

SRN

9

Charge current sense negative input.

SRP

10

Charge current sense positive input. A 0.1-uF is recommended for common mode filtering from SRP to

AGND. A 0.1uF is placed from SRP to SRN for differential mode filtering.

GND

11

Power ground.

REGN

12

5V power supply output, Bypass 1uF MLCC to AGND.

SW

13.14

Switching node, charge current output inductor connection. Connect a 47-nF BS capacitor from SW

to BS.

PVCC

15.16 IC power supply of power device of Charger. Put 10uF MLCC from PVCC to PGND.

BS

17

Boostrap pin. Place a 0.047u-F MLCC from SW to BS.

BATDRV 18

Battery discharge MOSFET gate driver output. Connect a 1kohm resistor to the gate of the P-channel

power MOSFET(BATFET). Connect the source of the BATFET to the system load voltage node.

Connect the drain of the BATFET to the battery pack positive node. The internal

gate drive is asymmetrical to allow a quick turn-off and slower turn-on. The internal

break-before-make logic with respect to ACDRV. There is an internal 50k pull-down resistor from

BATDRV to ground.

ACN

19

Adaptor current sense resistor negative input. A 0.1-uF from ACN to AGND is recommended for common

mode filtering. A 0.1uF is placed from ACN to ACP for differential mode filtering.

ACP

20

Adaptor current sense resistor positive input. A 0.1-uF from ACP to AGND is recommended for common

mode filtering. A 0.1uF is placed from ACN to ACP for differential mode filtering.