Single-cell Li-ion / Li-polymer Battery Protection IC
Rev. E09-06
A7B Series
Over-charge detection
When the battery voltage (V
DD
) under the normal condition becomes equal to or higher than the over-charge
detection voltage (Vc) and that state is maintained during more than the over-charge detection delay time (tc),
this IC turns off the charge control FET and stops charge. This state is called the over-charge detection condition.
Release from the over-charge detection condition includes following three cases.
(1) When V
DD
falls to Vc-VHc without load and that state is maintained during more than the delay time 2 (trel2),
this IC turns on the charge control FET and returns to the normal condition.
* VHc : Over-charge hysteresis voltage
(2) When the load is installed and discharge starts, the discharge current flows through the internal parasitic
diode of the charge control FET. Then the V
M
terminal voltage rises to only the Vf voltage of the internal
parasitic diode from V
SS
potential. At this time, if the V
M
terminal voltage is higher than the discharge over-
current detection voltage (VIdc) and V
DD
is equal to or less than Vc, this IC returns to the normal condition
when this state continues more than the delay time 2 (trel2).
(3) In case (2), if the VM terminal voltage is higher than the discharge over-current detection voltage (VIdc) and
V
DD
is equal to or higher than Vc, battery is discharged until V
DD
becomes less than Vc, and then this IC
returns to the normal condition when this state continues more than the delay time 2 (trel2).
Over-discharge detection
When the battery voltage (V
DD
) under the normal condition becomes equal to or less than the over-discharge
detection voltage (Vdc) and that state is maintained during more than the over-discharge detection delay time
(tdc), this IC turns off the discharge control FET and stops discharge. This state is called the over-discharge
detection condition. The over-discharge detection condition is released when the charger is connected and
following three cases are included.
(1) When the charger is connected and charge starts, the charge current flows through the internal parasitic
diode of the discharge control FET. V
DD
is higher than Vdc and that state is maintained during more than the
delay time 1 (trel1), this IC is released from over-discharge detection condition automatically and returns to
the normal condition.
(2)
(3)
In case (1), if V
DD
is less than Vdc, this IC returns to the normal condition when V
DD
becomes equal to or
higher than Vdc and this state continues more than the delay time 1 (trel1).
Although there is very little possibility, in case (1), if the V
M
terminal voltage is higher than the charge over-
current detection voltage (VIc) even if the charge current flows through the internal parasitic diode of the
discharge control FET, this IC returns to the normal condition when V
DD
becomes equal to or higher than
Vdc+VHdc and this state continues more than delay time 1 (trel1).
* VHdc = 0.4V (typical)
---- This voltage is tested in production, but is not specified.
This IC stops all internal circuits ( Shutdown condition ) after detecting the over-discharge and reduces current
consumption. ( Max 0.1µA, at V
DD
=1.8V )
Charge to 0V battery
(1)
0V battery charge function
If the voltage of charger (the voltage between V
DD
and V
M
) is larger than the 0V battery charge starting
charger voltage (Vcha), 0V battery charge becomes possible when C
O
terminal outputs V
DD
terminal
potential and turns on the charge control FET.
(2)
0V battery charge inhibiting function
If the voltage of the battery (V
DD
) is equal to or less than the 0V battery charge inhibiting battery voltage
(Vinh), charge is inhibited when C
O
terminal outputs V
M
terminal potential and turns off a charge control FET.
11
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AnaSem Inc.
ANASEM [ AnaSem Hong Kong Limited ]
