RT9502

2

DS9502-02 April 2011

www.richtek.com

Typical Application Circuit

Functional Pin Description

Pin No.

Pin Name

Pin Function

1

ACIN

AC Adaptor Charge Input Supply.

2

USB

USB Charge Input Supply.

3

CHG_S

Charge Status Indicator Output (open drain).

4

PGOOD

Power Good Indicator Output (open drain).

5

GND

Ground.

6

ISETA

Wall Adaptor Supply Charge Current Set Point.

7

ISETU

USB Supply Charge Current Set Input (active low).

8

EN

Charge Enable Input (active low).

9

TS

Temperature Sense Input.

10

BATT

Battery Charge Current Output.

11 (Exposed Pad)

GND

The exposed pad must be soldered to a large PCB and connected to GND for

maximum power dissipation.

RT9502

1uF

AC

Adapter

ACIN

USB

GND

BATT

TS

ISETA

ISETU

USB

1uF

H : 500mA

L : 100mA

Battery Pack

1

2

3

4

5, Exposed Pad(11)

6

7

8

9

10

CHG_S

PGOOD

EN

To System

To System

Chip Shutdown

Chip Enable

0.1uF to 10uF

Pre-Charge Phase

Fast Charge

Phase

Constant Voltage

Phase &

Standby Phase

Re-Charge Phase

Programmed

Charge Current

4.1V Recharge

Threshold

2.8V Precharge

Threshold

1/10 Programmed

Charge Current

Charge

Complete

Battery

Voltage

Charging

Current