S-8232 Datasheet, PDF (19/27 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK

Rev.5.4_00
BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK
S-8232 Series
„ Precautions
• After the overcurrent detection delay, if either one of battery voltages equals the overdischarge detection
voltage (V_DD1,2) or lower, the overdischarge detection delay time becomes shorter than 10ms (min.). It
occurs because capacitor C3 sets all of delay times (refer to the Figure 9) .
VDD
Battery
voltage
0V
The battery voltage is equal to
or less the overdischarge voltage (VDD)
after stopping the overcurrent.
VCC
DO pin
voltage
VSS
VM pin
voltage
VCC
V IOV2
V IOV1
VSS
EB−
The over current delay
Load connect
The over discharge delay
The delay time becomes shorter than typical
Figure 9
[Cause]
When overcurrent detection is released until t_IOV1, the capacitor C3 is charged by S-8232 Series. If all
battery voltage is lower than V_{DD1, 2} at that time, charging goes on. So delay time is shorter than
typical.
[Conclusion]
This phenomenon occurs when all battery voltage is nearly equal to the overdischarge voltage (V_{DD1, 2})
after overcurrent detected. It means that the battery capacity is small and those must be charged in
the future. Even if the state changes to overdischarge condition, the battery package capacity is same
as typical.
• When one of the battery voltages is overdischarge detection voltage (V_{DD1, 2}) or lower and the other one
becomes higher than the overcharge detection voltage (V_{CU1, 2}), the IC detects the overcharge without the
overcharge detection delay time (t_CU) (refer to the Figure 10) .
Battery
voltage
V1
VCU
VCD
V DU ^{Overcharge detect}
VDD
Overdischarge state
VCU
Battery V_CD
voltage
V2
VDU
VDD
CO pin
voltage
VCC
VSS
EB−
Delay time = 0
Charger connected
Figure 10
[Cause]
It is same as the overdischarge detection under the overcurrent condition. It occurs because capacitor
C3 sets all of delay times.
[Conclusion]
This phenomenon occurs when one battery voltage is lower than overdischarge voltage (V_{DD1, 2}) and
batteries are charged by charger. Since voltage difference between two batteries is large in this
situation, the S-8232 Series immediately stops the charging of the other battery to reduce voltage
difference. This action improves the safety of a battery pack and dose not do any harm to the pack.
Seiko Instruments Inc.
19