AIC1783 View Datasheet(PDF) - Analog Intergrations

Part Name

Description

Manufacturer

AIC1783

Battery Charge Controller

Analog Intergrations 

AIC1783

n APPLICATION INFORMATIONS

OPERATION

Power-On and Battery Pre-qualifying

When power is first applied to the AIC1783, all

internal digital circuit blocks of the AIC1783 are

reset by the internal power-on-reset circuitry and

output LED flash 3 times to indicate the initiation of

power-on. The internal control unit then examines

the battery condition through the VBT pin.

The acceptable range of VBT pin is 0.16V to 2.7V. If

the voltage of VBT pin fails to fall within the

predetermined acceptable limits, the AIC1783

enters a charge-suspending mode, in which all the

internal circuitry remains in reset state.

Fast Charge

After the battery passes fault checks, fast charging

begins while initial timer and safety timer of the

AIC1783 start counting. Functions of −?V

detection, peak voltage timer, and maximum battery

voltage are, however, disabled temporarily until the

initial timer period in the initial stage of a charge

cycle elapses. The initial timer period is equal to

1/80 of safety timer.

Since the low limit of acceptable VBT voltage is only

about 0.16V during the initial timer period, even

deeply discharged batteries can easily qualify to be

fast charged subsequently.

In the course of fast charge, the AIC1783 constantly

monitors the voltages at VBT pin. The fast charge

process is switched to trickle charge when any one

of the following situations is encountered, which are

explained below:

l Negative delta voltage (−? V )

l Peak voltage timer ( 0? V )

l Maximum charge time

l Maximum battery voltage

-∆V Cutoff

The AIC1783 makes a voltage sampling at VBT pin

every 4 seconds when safety timer period is set

equal to 80 minutes. If a negative delta voltage of

0.25% compared to its peak value is detected at

VBT pin, the fast charge cycle is terminated.

0∆V Cutoff

If the battery voltage stays at its peak value or

decreases very slowly for the duration determined

by the peak voltage timer which is 6% of safety timer,

the fast charge action is terminated.

Maximum Safety Timer Cutoff

The maximum fast charge period is determined by

the safety timer, which is set by a resistor connected

from TIMER pin to GND. Safety timer, −?V

sampling rate will be longer if the resistor value is

larger. When the value of the resistor is 100KΩ, the

safety timer period equals 80 minutes. After the

safety timer period is finished, the fast charge action

is terminated.

Maximum Voltage Cutoff

The AIC1783 guards against the maximum limits for

battery voltage during fast charging. If either of

these limits is exceeded, fast charge action is

terminated.

Trickle Charge

The trickle charge after the fast charge to prevent

the loss of charge due to battery self-discharging.

The duty cycle is set to 1/128 by internal circuitry.

7

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