BATTERY PROTECTION IC FOR 1-CELL PACK
S-8261 Series
Rev.5.3_00
Seiko Instruments Inc.
24
Battery Protection IC Connection Example
R1 : 470
Ω
Battery
C1 :
0.1
μ
F
VSS
DO
VDD
CO VM
S-8261 Series
FET1 FET2
EB
−
EB
+
R2 : 2 k
DP
Figure 10
Table 17 Constant for External Components
Symbol Part Purpose Min. Typ. Max. Remarks
FET1
N-channel
MOS FET
Discharge control
⎯
⎯
⎯
Threshold voltage
≤
Overdischarge detection voltage
*1
Gate to source withstanding voltage
≥
Charger voltage
*2
FET2
N-channel
MOS FET
Charge control
⎯
⎯
⎯
Threshold voltage
≤
Overdischarge detection voltage
*1
Gate to source withstanding voltage
≥
Charger voltage
*2
R1 Resistor
ESD protection,
For power fluctuation
300
Ω
470
Ω
1 k
Ω
Resistance should be as small as possible to avoid lowering of
the overcharge detection accuracy caused by VDD pin current.
*3
C1 Capacitor For power fluctuation 0.022
μ
F 0.1
μ
F 1.0
μ
F
Install a capacitor of 0.022
μ
F or higher between VDD and
VSS.
*4
R2 Resistor
Protection for reverse
connection of a charger
300
Ω
2 k
Ω
4 k
Ω
Select a resistance as large as possible to prevent large current
when a charger is connected in reverse.
*5
*1. If the threshold voltage of an FET is low, the FET may not cut the charging current.
If an FET with a threshold voltage equal to or higher than the overdischarge detection voltage is used, discharging
may be stopped before overdischarge is detected.
*2. If the withstanding voltage between the gate and source is lower than the charger voltage, the FET may be destroyed.
*3. If R1 has a high resistance, the voltage between VDD and VSS may exceed the absolute maximum rating when a
charger is connected in reverse since the current flows from the charger to the IC. Insert a resistor of 300
Ω or higher
to R1 for ESD protection.
*4. If a capacitor of less than 0.022
μF is connected to C1, DO may oscillate when load short-circuiting is detected. Be
sure to connect a capacitor of 0.022
μF or higher to C1.
*5. If R2 has a resistance higher than 4 k
Ω, the charging current may not be cut when a high-voltage charger is
connected.
Caution 1. The above constants may be changed without notice.
2. The DP pin should be open.
3. 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 through evaluation using the actual application to set the
constant.
