AIC1802 AIC [Analog Intergrations Corporation], AIC1802 Datasheet - Page 9

• Manufacturer Part Number: AIC1802
• Description: Two-Cell Lithium-Ion Battery Protection IC
• Manufacturer: AIC [Analog Intergrations Corporation]

changes, the overcurrent threshold current will
change accordingly.
Suppressing the Ripple and Disturbance
from Charger
To suppress the ripple and disturbance from
charger, connecting C1 to cell 1 and C2 to cell 2 is
necessary.
Controlling the Charge Control
R3, R4, R5 and NPN transistor Q1 are used to
switch the charge control MOSFET M2. If
overcharge does not occur, no current flows out
from OC pin and Q1 are turned off, then M2 is
turned on. When overcharge occurs, current flows
out from OC pin and Q1 is turned on, which turns
off M2 in turn. High resistance for R3, R4, and R5
is recommended for reducing loading of the
batteries.
Latch-Up Protraction at CS Pin
R6 is used for latch-up protection when charger is
connected under overdischarge condition, and
also for overstress protection when charger is
connected in reverse. The charge detection
function after overdischarge is possibly disabled
by larger value of R6. Resistance of 1K
recommended.
Selection of R1 and R 2
R1 and R2 are used to avoid large current flow
through the battery pack under the situation of IC
damage or pin short. On the other hand,
resistance of R1 and R2 will affect overcharge
MOSFET
is
release voltage and bleeding function. The
relationship among Vrelease1,Vrelease2, R1, and
R2 is shown as following equations:
Vrelease1=V
Vrelease2=V
where
Therefore, resistance of R1 and R2 should not
higher than 30 . Otherwise, overcharge release
voltage
protection voltage and the charging current may
oscillate. In addition, if overcharge protection
function occurs, AIC1802 will discharge the
overcharged cell and will stop bleeding function
even if the voltage is not equal to the other. The
recommended resistance of R1 and R2 is from 20
to 30 .
Effect of C3
C3 has to be applied to the circuit. Because C3
will
overdischarge occurred. In addition, when the
differential voltage between charger and battery
pack is higher than 2.1V and overcharge
protection function work, C3 will avoid battery
pack from being charged even if the battery
voltage lower than 4V (To avoid battery pack from
being
situation). The battery pack can be charged again
till remove it from charger.
Vrelease1 is Battery 1, real overcharge release
voltage
Vrelease2 is Battery 2, real overcharge release
voltage
keep
charged
would
OCR
OCR
AIC1802
+I
+I
UD
UD
be
under
*R1
*R2
higher
to
charger
be
than
charged
AIC1802
malfunction
overcharge
after
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