LP3947

USB/AC Adaptor, Single Cell Li-Ion Battery Charger IC

General Description

The LP3947 is a complete charge management system that

safely charges and maintains a Li-Ion battery from either

USB power source or AC adaptor. In USB mode, the LP3947

supports charging in low power or high power mode. Alter-

natively, the LP3947 can take charge from AC adaptor. In

both USB and AC adaptor modes, charge current, battery

regulation voltage, and End of Charge (EOC) point can be

selected via I

default values that are pre-programmed in the factory. The

battery temperature is monitored continuously at the Ts pin

to safeguard against hazardous charging conditions. The

charger also has under-voltage and over-voltage protection

as well as an internal 5.6 hr timer to protect the battery. The

pass transistor and charge current sensing resistor are all

integrated inside the LP3947.

The LP3947 operates in four modes: pre-qualification, con-

stant current, constant voltage and maintenance modes.

There are two open drain outputs for status indication. An

internal amplifier readily converts the charge current into a

voltage. Also, the charger can operate in an LDO mode

providing a maximum of 1.2 Amp to the load.

Features

n

Supports USB Charging Scheme

n

Integrated Pass Transistor

n

Near-Depleted Battery Preconditioning

n

Monitors Battery Temperature

n

Built-In 5.6 hour timer

n

Under Voltage and Over Voltage Lockout

n

Charge Status Indicators

n

Charge Current Monitor Analog Output

n

LDO Mode Operation can source 1 Amp

n

Continuous Over Current/Temperature Protection

Key Specifications

n

1% Charger Voltage Accuracy Over 0˚C

≤ T

J

≤ 85˚C

n

4.3V to 6.0V Input Voltage Range

n

100 mA to 750 mA charge current range, in charger

mode

n

100mA to 500mA charge current range, in USB mode

n

LLP Package Power Dissipation: 2.7W at T

Applications

n

Cellular Phones

n

PDAs

n

Digital Cameras

n

USB Powered Devices

n

Programmable Current Sources

Typical Application Circuit

20111001

More Application Circuit can be found in the Application Note section.

November 2004

© 2004 National Semiconductor Corporation

DS201110

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