Revision 11/2/2010

Preliminary and all contents are subject to change without prior notice

© Seaward Electronics Inc., 2007. • www.seawardinc.com.cn • Page 1

Description

SE9021 is a complete Limit-current & constant

voltage charger for single cell Lithium-ion and

Lithium-Polymer batteries. Its COB package and low

external component count make SE9021 ideally

suited for Low Cost and portable applications.

Furthermore, the SE9021 is specifically designed to

work for Universal Travel Charger Applications.

SE9021 has a built-in detector that will

automatically detect the polarity of the inserted

battery and charge the battery at the correct polarity.

The max charging current is around 250mA, at the

start of the charging. This will minimize the charging

time. The target battery final voltage is fixed at 4.22V.

As the battery approaches 4.22V, SE9020 will

gradually

reduce

charging

current

to

avoid

overcharging,

which

might

result

in

battery

deformation

or

even

explosion.

The

SE9021

automatically terminates the charge cycle when the

charge current drops to 30mA after the final target

voltage is reached.

To reduce power consumption and minimize

heat dissipation requirements, SE9021 is designed to

provide up to 250mA charging current at Vin=5V. This

reduces the power consumption to about 50% when

compared to other IC’s. As further insurance, SE9021

is equipped with Over-Temperature-Protection. This

makes sure that SE9021 is the only safe IC to be

used in lower power and low cost COB package.

When the input supply is removed, the SE9021

automatically enters a low current stage, or Green

Mode operation, dropping the battery drain current to

less than 7uA.

The SE9021 can be put into

shutdown mode, reducing the supply current to 30uA.

SE9021 supports various LED display options,

as outlined in the Application section below.

SE9021 is available in COB SOP8 and DIP8

options.

Application

Universal Travel Charger (AUC)

4 LED Waterfall Display Option

3 LED Running Display Option

2 LED Flashing Display Option

1 LED Simple Display Option

Features

Automatically Identifies the polarity of the battery

Typical-Current to 250mA

Scalable for higher charging currents, such as

Dual-Core for 500mA, Tri-Core for 750mA, and

Quad-Core for 1A charging currents.

Short-Circuit Protection

Low external component

Build in high precision reference voltage

Preset 4.22V Charge Voltage with ±50mV

Accuracy.

20uA Supply Current in Shutdown.

Support Standalone Battery Charger.

Support various LED Display schemes.

Available in DIP-8 and COB Packages.

Pin Configuration

COB