BATTERY PROTECTION IC FOR 1-CELL PACK
S-8241 Series
Rev.7.6_00
Battery Protection IC Connection Example
EB
+
R1 : 470
Ω
VDD
VSS
Battery
C1 :
0.1
S-8241 Series
μ
F
DO
CO
VM
R2 : 1 k
Ω
FET1
FET2
EB−
Figure 12
Table 15 Constants for External Components
Symbol
FET1
Parts
Nch
Purpose
Typ.
min.
max.
Remarks
0.4 V
≤
Threshold voltage
≤
overdischarge detection voltage. *1
Withstand voltage between gate and
Discharge control
⎯
⎯
⎯
MOS_FET
source
0.4 V
≥
Charger voltage *2
≤
Threshold voltage ≤
Nch
MOS_FET
overdischarge detection voltage. *1
Withstand voltage between gate and
FET2
Charge control
⎯
⎯
⎯
source
Relation R1
≥
Charger voltage *2
Protection for ESD and
power fluctuation
Protection for power
fluctuation
≤
R2 should be
R1
C1
Resistor
R2 value
470
Ω
300 Ω
maintained.*3
Install a capacitor of 0.01 μF or
Capacitor
0.1
μ
F
0.01
μ
F
1.0
μ
F
higher between VDD and VSS. *4
To suppress current flow caused by
reverse connection of a charger, set the
Protection for charger
reverse connection
R2
Resistor
1 kΩ
300
Ω
1.3 kΩ
resistance within the range from 300
Ω to
*5
1.3 kΩ.
*1. If an FET with a threshold voltage of 0.4 V or lower is used, the FET may fail to cut the charging current.
If an FET with a threshold voltage equal to or higher than the overdischarge detection voltage is used, discharging may stop
before overdischarge is detected.
*2. If the withstand voltage between the gate and source is lower than the charger voltage, the FET may break.
*3. If R1 has a higher resistance than R2 and if a charger is connected reversely, current flows from the charger to the IC and the
voltage between VDD and VSS may exceed the absolute maximum rating. Install a resistor of 300
protection.
Ω or higher as R1 for ESD
If R1 has a high resistance, the overcharge detection voltage increases by IC current consumption.
*4. If a capacitor C1 is less than 0.01 F, DO may oscillate when load short-circuiting is detected, a charger is connected
reversely, or overcurrent 1 or 2 is detected.
A capacitor of 0.01 F or higher as C1 should be installed. In some types of batteries DO oscillation may not stop unless the
C1 capacity is increased. Set the C1 capacity by evaluating the actual application.
*5. If R2 is set to less than 300 , a current which is bigger than the power dissipation flows through the IC and the IC may break
μ
μ
Ω
when a charger is connected reversely. If a resistor bigger than 1.3 k
when a high-voltage charger is connected.
Ω is installed as R2, the charging current may not be cut
Caution 1. The above constants may be changed without notice.
2. It has not been confirmed whether the operation is normal or not in circuits other than the above example
of connection. In addition, the example of connection shown above and the constant do not guarantee
proper operation. Perform thorough evaluation using the actual application to set the constant.
26
Seiko Instruments Inc.
SII [ SEIKO INSTRUMENTS INC ]
