Vishay Siliconix

Si9731

Document Number: 71321

S09-2249-Rev. C, 26-Oct-09

www.vishay.com

1

µP Controlled Battery Charger

for 1-Cell Li-ion or 1-Cell to 3-Cell NiCd/NiMH Batteries

FEATURES

•

Pulse charges 1-cell Li-ion or 1-cell to 3-cell

NiCd/NiMH batteries

•

Integrated MOSFETs with bi-directional

reverse current blocking in "OFF" mode

•

PWM controlled fast charging mode

•

Low current trickle charge mode

•

Pin selectable 4.1 V or 4.2 V charge termination for Li-ion

•

Constant voltage (CV) termination for Li-ion

•

Input over-voltage detector with automatic shutdown

•

External shutdown

•

Under 1 µA reverse battery leakage current in shutdown

•

Complete isolation from battery to external power supply

in shutdown

•

Thermal shutdown

•

Minimum number of external components

•

ESD protection to 4 kV on charger input and battery

output

•

TSSOP-16 package (1.2 mm maximum height)

•

Halogen-free according to IEC 61249-2-21 definition

•

Compliant to RoHS directive 2002/95/EC

APPLICATIONS

•

Cellular phone battery charger

•

Personal digital assistants

DESCRIPTION

Si9731 is a chemistry independent battery charger designed

to pulse charge 1-cell to 3-cell NiCd/NiMH or 1-cell Li-ion

batteries. Battery charging is accomplished under direct

MOSFET can be pulsed on and off at varying duty cycle by

the system processor to pulse charge the battery at high

charge current while minimizing heat dissipation. Provision is

also made to trickle charge a discharged battery until the

battery is charged to a high enough voltage to wake up the

processor so that the processor can take control of the

charging process. For charging Li-ion batteries, Si9731

includes a precision voltage reference and an error amplifier

for constant voltage (CV) charge mode. The Si9731 is

available in lead (Pb)-free TSSOP-16 package and is

classified over the industrial temperature range (- 40 °C to

+ 85 °C).

FUNCTIONAL BLOCK DIAGRAM

B

a

t

t

e

r

y

ON/OFF

TRICKLECHARGEENABLE

Trickle

Charge

Fast

Charge

4.1/4.2 V_TAP

FAST CHARGE

Charge Control

GND