AAT3663 datasheet(13/22 Pages) ANALOGICTECH

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AAT3663

1A Linear Li-Ion Battery Charger

for Single and Dual Cell Applications

3663.2007.10.1.0

Application Information

Adapter or USB Power Input

Constant current charge levels up to 1A may be

programmed by the user when powered from a suf-

ficient input power source. The AAT3663 will oper-

ate over an input voltage range from 4.0V to 13.2V.

The low input voltage capability of the AAT3663

permits charging single cell Li-Ion/Poly batteries

from USB ports and lower voltage input power

sources. The high 13.2V input rating of this device

allows for the use of a wide range of input power

sources for both single and dual cell Li-Ion/Poly

applications.

Adapter Input Charge Inhibit and

Resume

The AAT3663 has an under-voltage lockout (UVLO)

and power on reset feature so that if the input sup-

ply to the IN pin drops below the UVLO threshold,

the charger will suspend charging and shut down.

When power is reapplied to the IN pin or the UVLO

condition recovers, the system charge control will

assess the state of charge on the battery cell and will

automatically resume charging in the appropriate

mode for the condition of the battery.

Battery Connection and Battery Voltage

Sensing

Battery Connection

A single or dual cell Li-Ion/Polymer battery should

be connected between the BAT pin and ground.

Battery Voltage Sensing

The BATS pin is provided to employ an accurate

voltage sensing capability to measure the positive

terminal voltage at the battery cell being charged.

This function reduces measured battery cell volt-

age error between the battery terminal and the

charge control IC. The AAT3663 charge control cir-

cuit will base charging mode states upon the volt-

age sensed at the BATS pin. The BATS pin must

be connected to the battery terminal for correct

operation. If the battery voltage sense function is

not needed, the BATS pin should be terminated

directly to the BAT pin. If there is concern of the

battery sense function inadvertently becoming an

open circuit, the BATS pin may be terminated to the

BAT pin using a 10k

Ω resistor. Under normal oper-

ation, the connection to the battery terminal will be

close to 0

Ω; if the BATS connection becomes an

open circuit, the 10k

Ω resistor will provide feed-

back to the BATS pin from the BAT connection with

a voltage sensing accuracy loss of 1mV or less.

Enable (EN)

EN is a logic input (active high) to enable the

charger, this function is internally pulled down to

ground. When the device is initially enabled or if

the EN pin is cycled low and then re-enabled, the

charge control circuit will automatically reset and

resume charging functions with the appropriate

charging mode based on the battery charge state

and measured battery voltage on the BATS pin.

Programming Charge Current

The constant current mode charge level is user pro-

grammed with a set resistor (R

SET)

connected

between the ISET pin and ground. The accuracy of

the constant charge current, as well as the precon-

ditioning trickle charge current, is dominated by the

tolerance of the set resistor used. For this reason, a

1% tolerance metal film resistor is recommended for

the set resistor function. The constant charge cur-

rent levels from 100mA to 1A may be set by select-

ing the appropriate resistor value from Table 1.

Table 1: R

SET Values.

Constant Charging

Set Resistor

Current (mA)

Value (kΩ)

100

17.8

200

8.87

300

5.9

400

4.42

500

3.57

600

2.94

700

2.55

800

2.21

900

1.96

1000

1.78

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