S-8242B Datasheet, PDF (17/30 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK

Rev.1.4_00
BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK
S-8242B Series
„ Battery Protection IC Connection Example
EB+
R1
VDD
Battery 1
C1
R2
VC
S-8242B Series
Battery 2
C2
VSS
DO
CO
VM
R3
FET1
FET2
EB−
Figure 13
Table 7 Constants for External Components
Symbol
FET1
FET2
Parts
Purpose
N-channel
MOS FET
Discharge control
N-channel
MOS FET ^{Charge control}
Typ.
Min.
Max.
Remark



Threshold voltage≤Overdischarge detection voltage^*2
Gate to source withstanding voltage≥Charger voltage^*3



Threshold voltage≤Overdischarge detection voltage^*2
Gate to source withstanding voltage≥Charger voltage^*3
R1
Resistor
ESD protection,
For power fluctuation
100 Ω
10 Ω^*1
Resistance should be as small as possible to avoid lowering
220 Ω^*1 the overcharge detection accuracy due to current
consumption.^*4
C1 Capacitor For power fluctuation
1 µF
0.47 µF^*1
10 µF^*1
Connect a capacitor of 0.47 µF or higher between VDD and
VSS.^*5
ESD protection,
R2 Resistor _{For power fluctuation}
1 kΩ
300 Ω^*1
1 kΩ^*1

C2 Capacitor For power fluctuation
0.1 µF
0.022 µF^*1 1.0 µF^*1

R3
Resistor ^{Protection for reverse}
connection of a charger
2 kΩ
300 Ω
4 kΩ
Select as large a resistance as possible to prevent current
when a charger is connected in reverse.^*6
*1. Please set up a filter constant to be R2 × C2 ≥ 20 µF • Ω, and to be R1 × C1 = R2 × C2.
*2. If the threshold voltage of a FET is low, the FET may not cut the charging current.
If a FET with a threshold voltage equal to or higher than the overdischarge detection voltage is used, discharging may be
stopped before overdischarge is detected.
*3. If the withstanding voltage between the gate and source is lower than the charger voltage, the FET may be destroyed.
*4. 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 10 Ω or higher to R1 for ESD protection.
*5. If a capacitor of less than 0.47 µF is connected to C1, DO pin may oscillate when load short-circuiting is detected. Be
sure to connect a capacitor of 0.47 µF or higher to C1.
*6. If R3 has a resistance higher than 4 kΩ, 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. 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.
Seiko Instruments Inc.
17