s-8242bac-i8t1g Seiko Instruments Inc., s-8242bac-i8t1g Datasheet - Page 18

• Manufacturer Part Number: s-8242bac-i8t1g
• Description: Battery Protection Ic For 2-serial-cell Pack
• Manufacturer: Seiko Instruments Inc.

*1. Please set up a filter constant to be R2 × C2 ≥ 20 µ F • 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.
*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
*5. If a capacitor of less than 0.47 µ F is connected to C1, DO pin may oscillate when load short-circuiting is detected. Be
*6. If R3 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.
18
Symbol
BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK
S-8242B Series
FET1
FET2
R1
C1
R2
C2
R3
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.
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.
sure to connect a capacitor of 0.47 µ F or higher to C1.
Battery Protection IC Connection Example
2. It has not been confirmed whether the operation is normal or not in circuits other than the above
N-channel
N-channel
MOS FET
MOS FET
Capacitor For power fluctuation
Capacitor For power fluctuation
Resistor
Resistor
Resistor
Parts
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.
Discharge control
Charge control
ESD protection,
For power fluctuation
ESD protection,
For power fluctuation
Protection for reverse
connection of a charger
Battery 1
Battery 2
Purpose
Table 7 Constants for External Components
R1
R2
0.1 µ F
100 Ω
C1
1 µ F
1 k Ω
2 k Ω
Typ.


C2
Seiko Instruments Inc.
VDD
VC
VSS
0.022 µ F
0.47 µ F
300 Ω
10 Ω
300 Ω
Min.
DO


Figure 13
*1
*1
FET1
*1
*1
S-8242B Series
1.0 µ F
220 Ω
10 µ F
1 k Ω
Max.
4 k Ω
CO


*1
*1
*1
*1
FET2
Threshold voltage ≤ Overdischarge detection voltage
Gate to source withstanding voltage ≥ Charger voltage
Threshold voltage ≤ Overdischarge detection voltage
Gate to source withstanding voltage ≥ Charger voltage
Resistance should be as small as possible to avoid lowering
the overcharge detection accuracy due to current
consumption.
Connect a capacitor of 0.47 µ F or higher between VDD and
VSS.
Select as large a resistance as possible to prevent current
when a charger is connected in reverse.
*5
VM
R3
*4
Remark


EB+
EB−
*6
Rev.1.9
*2
*2
*3
*3
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