AAT3783

1-A Linear Li-Ion/Polymer Battery Charger with 28V Over-Voltage Protection

PRODUCT DATASHEET

10

3783.2008.08.1.2

www .analogictech.com

AAT3783

1-A Linear Li-Ion/Polymer Battery Charger with 28V Over-Voltage Protection

PRODUCT DATASHEET

10

3783.2008.08.1.2

www .analogictech.com

Functional Description

The AAT3783 is a high performance battery charger

designed to charge single cell Lithium-Ion or Polymer

batteries with up to 1000mA of current from an external

power source. It is a stand-alone charging solution, with

just one external component required (two more for

options) for complete functionality. Also included is input

voltage protection (OVP) to up to +28V. OVP consists of

a low resistance P-channel MOSFET in series with the

charge control MOSFET, and also consists of under-volt-

age lockout protection, over-voltage monitor, and fast

shut-down circuitry with a fault output flag.

Battery Charging Operation

Figure 1 illustrates the entire battery charging profile or

operation, which consists of three phases:

1. Preconditioning (Trickle) Charge

2. Constant Current Charge

3. Constant Voltage Charge

Battery Preconditioning

Battery charging commences only after the AAT3783

checks several conditions in order to maintain a safe

charging environment. The input supply must be above

pin must be high. When the battery is connected to the

BAT pin, the AAT3783 checks the condition of the battery

and determines which charging mode to apply. If the

battery voltage is below the preconditioning voltage

ing the battery cell (trickle charging) by charging at 10%

of the programmed constant current. For example, if the

programmed current is 500mA, then the preconditioning

mode (trickle charge) current is 50mA. Battery cell pre-

conditioning (trickle charging) is a safety precaution for

deeply discharged cells and will also reduce the power

dissipation in the internal series pass MOSFET when the

input-output voltage differential is at the greatest poten-

tial.

Functional Block Diagram

Charge

Control

Current

Compare

Reverse Blocking

Constant

Current

BAT

ISET

UVLO

Over

Temp.

Protect

Power

Detection

STAT

GND

Thermal

Loop

ADPP

Charge

Status

OVP

Sense

and

Control

ENOVP

IN

FLT

ENCHR

INCHR

IN

BAT S

CV/Pre-

Charge

CT

TS

TERM

OVP

Over-Current

Protection