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

VIN

R2

2

1

C1

0.2Ω

J1

GND

22μF R1

2.2K

R5

100K

C5

4.7μF

U1

AAT3682

R3

1K

C4

1000pF

1 TS

N/C 12

D2

Green LED

2 N/C

3 N/C

4 STAT

GATE 11

VSS 10

BAT 9

J2

1

Remove capacitor for

progressive dimming

C3

47nF

R6

100K

D1

C2

10μF

2

3

R4

1K

R7

100K

3 S1

2

1

SW-T2X

Figure 5: Evaluation Board Schematic.

Protection Circuitry

The AAT3682 is a highly integrated battery manage-

ment system IC including several protection fea-

tures. In addition to battery temperature monitoring,

the IC constantly monitors for over-current and over-

voltage conditions; if an over-current situation

occurs, the AAT3682 latches off the pass device to

prevent damage to the battery or the system, and

enters shutdown mode until the over-current event is

terminated. An over-voltage condition is defined as a

condition where the voltage on the BAT pin exceeds

the maximum battery charge voltage. If an over-volt-

age condition occurs, the IC turns off the pass

device until voltage on the BAT pin drops below the

maximum battery charge constant voltage threshold.

The AAT3682 will resume normal operation after the

over-current or over-voltage condition is removed.

During an over-current or over-voltage event, the

STAT will report a FAULT signal. In the event of a

battery over-temperature condition, the IC will turn

off the pass device and report a FAULT signal on the

STAT pin. After the system recovers from a temper-

ature fault, the IC will resume operation in the 1X

trickle charge mode to prevent damage to the sys-

tem in the event a defective battery is placed under

charge. Once the battery voltage rises above the

trickle charge to constant current charge threshold,

the IC will resume the constant current mode.

3682.2006.12.1.3

Applications Information

Choosing a Sense Resistor

The charging rate recommended by lithium-

ion/polymer cell vendors is normally 1C, with a 2C

absolute maximum rating. Charging at the highest

recommended rate offers the advantage of short-

ened charging time without decreasing the battery's

lifespan. This means that the suggested fast

charge rate for a 500mAH battery pack is 500mA.

Refer to the Safe Operating Area curves in the

Typical Characteristics section of this datasheet to

determine the maximum allowable charge current

for a given input voltage. The current sense resistor,

RSENSE, programs the charge current according to

the following equation:

RSENSE =

VCC - VCSI

ICHARGE

Where ICHARGE is the desired typical charge current

during constant current charge mode. VCC - VCSI is

the voltage across RSENSE, shown in the Electrical

Characteristics table as VCS. To program a nominal

500mA charge current during fast charge, a

200mΩ value resistor should be selected.

13

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