AAT3682 查看數據表（PDF） - Advanced Analogic Technologies

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AAT3682

Lithium-Ion/Polymer Battery Charger

Advanced Analogic Technologies 

AAT3682

Lithium-Ion/Polymer Linear Battery Charger

system. This is done to prevent the charger from

erroneously turning on and off once a battery

charge cycle is complete.

For example, the AAT3682 has a typical VRCH

threshold of 4.1V. A battery under charge is above

4.1V, but is still in the constant voltage mode

because it has not yet reached 4.2V to complete

the charge cycle. If the battery is removed and

then placed back on the charger, the charge cycle

will not resume until the battery voltage drops

below the VRCH threshold. In another case, a bat-

tery under charge is in the constant current mode

and the cell voltage is 3.7V when the input supply

is inadvertently removed and then restored. The

battery is below the VRCH threshold and the charge

cycle will immediately resume where it left off.

LED Display Charge Status Output

The AAT3682 provides a battery charge status out-

put via the STAT pin. STAT is an open-drain serial

data output capable of displaying five distinct status

functions with one LED connected between the

STAT pin and VP. There are four periods which

determine a status word. Under default conditions,

each output period is one second long; thus one

status word will take four seconds to display

through an LED. The five modes include:

1. Sleep/Charge Complete: The IC goes into

Sleep mode when no battery is present -OR-

when the charge cycle is complete.

2. Fault: When an over-current (OC) condition is

detected by the current sense and control cir-

cuit -OR- when an over-voltage (OV) condition

is detected at the BAT pin -OR- when a battery

over-temperature fault is detected on the

TEMP pin.

3. Battery Conditioning: When the charge system

is in 1X or 2X trickle charge mode.

4. Constant Current (CC) Mode: When the sys-

tem is in constant current charge mode.

5. Constant Voltage (CV) Mode: When the sys-

tem is in constant voltage charge mode.

An additional feature of the LED status display is for

a Battery Not Detected state. When the AAT3682

senses there is no battery connected to the BAT

pin, the STAT output will turn the LED on and off at

a rate dependent on the size of the output capacitor

being used. The LED cycles on for two periods then

remains off for two periods. See Figure 3 below.

Charge Status

Sleep / Charge Complete

Temp., OC, OV Fault

Battery Conditioning

Constant Current Mode

Constant Voltage Mode

Output Status

off / off / off / off

on / on / off / off

on / on / on / on

on / on / on / off

on / off / off / off

on/off

ON

OFF

ON

OFF

ON

OFF

ON

OFF

ON

OFF

LED Display

on/off on/off

on/off

Figure 3: LED Display Output.

3682.2006.12.1.3

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