AIC1783 AIC [Analog Intergrations Corporation], AIC1783 Datasheet - Page 7

• Manufacturer Part Number: AIC1783
• Description: Battery Charge Controller
• Manufacturer: AIC [Analog Intergrations Corporation]

n
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 e xamines
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
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
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
l
APPLICATION INFORMATIONS
Negative delta voltage (
Peak voltage timer (
start
acceptable
counting.
0
? V
? V
)
Functions
limits,
)
the
of
AIC1783
? V
l
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- 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,
sampling rate will be longer if the resistor value is
larger. When the value of the resistor is 100K , the
safety timer p eriod equals 80 minutes.
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.
Maximum charge time
Maximum battery voltage
AIC1783
After the
? V
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