AAT3670 データシートの表示（PDF） - Advanced Analogic Technologies

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AAT3670

1.6A Dynamic Battery Charger and Power Manager

Advanced Analogic Technologies 

BatteryManagerTM

PRODUCT DATASHEET

AAT3670

1.6A Dynamic Battery Charger and Power Manager

End of Charge Voltage

Regulated Current

Preconditioning

Trickle Charge

Phase

Constant Current

Charge Phase

I = Max CC

Constant Voltage

Charge Phase

(4.2V)

Constant Current Mode

Voltage Threshold

(2.9V)

Trickle Charge

Charge Termination Current

Figure 1: Current vs. Voltage Profile During Charging Phases.

The battery preconditioning trickle charge current is

equal to the fast charge constant current divided by 10

for the adapter and USB high input modes. For example,

if the programmed fast charge current is 500mA, then

the preconditioning mode (trickle charge) current will be

50mA. In the USB low charging mode, the precondition-

ing current is set to the programmed fast charge current

divided by two. Cell preconditioning is a safety precau-

tion for a deeply discharged battery and also aids in

limiting power dissipation in the charge control pass

transistor when the voltage across the device is at the

greatest potential.

Fast Charge/Constant Current Charging

Battery cell preconditioning continues until the voltage

measured by the battery sense (BATS) pin exceeds the

preconditioning voltage threshold (VMIN). At this point,

the AAT3670 begins constant-current charging fast

charging phase. The fast charge constant current (ICC)

level is determined by the charge mode (ADP, USBH or

USBL) and is programmed by the user via the RADPSET and

RUSBSET resistors. The AAT3670 remains in constant cur-

rent charge mode until the battery reaches the voltage

regulation point, VBAT_EOC.

Constant Voltage Charging

The charge control system transitions to a regulated con-

stant voltage charging mode when the battery voltage

reaches output charge regulation threshold (VBAT_EOC) dur-

ing constant current fast charge phase. The regulation

voltage level is factory programmed to 4.2V (±1%). The

charge current in the constant voltage mode drops as the

battery cell under charge reaches its maximum capacity.

End of Charge Cycle Termination

and Recharge Sequence

When the charge current drops to the user programmed

charge termination current at the end of the constant volt-

age charging phase, the device terminates charging and

enters the sleep state. The charger will remain in the sleep

state until the battery voltage decreases to a level below

the battery recharge voltage threshold (VRCH). The charge

termination current is programmed via the RTERM resistor.

When the input supply is disconnected, the charger also

automatically enters power-saving sleep mode. Only

consuming an ultra-low 1µA in sleep mode, the AAT3670

minimizes battery drain when not charging. This feature

is particularly useful in applications where the input sup-

ply level may fall below the usable range of the charge

reduction control or under-voltage lockout level. In such

cases where the AAT3670 input voltage drops, the device

will enter the sleep mode and automatically resume

charging once the input supply has recovered from its

fault condition.

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