S-8252AAA-M6T1U Datasheet, PDF (21/36 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC

Rev.3.2_00
BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK
S-8252 Series
 Battery Protection IC Connection Example
EB+
R1
VDD
Battery 1
C1
R2
VC
S-8252 Series
Battery 2
C2
VSS
DO
CO
VM
R3
FET1
FET2
EB−
Figure 14
Table 11 Constants for External Components
Symbol Part
Purpose
Typ.
Min.
Max.
Remark
Threshold voltage ≤ Overdischarge
FET1
N-channel
MOS FET
Discharge control
−
−
detection voltage^*2
−
Gate to source withstand voltage ≥
Charger voltage^*3
FET2
N-channel
MOS FET
Charge control
Threshold voltage ≤ Overdischarge
detection voltage^*2
−
−
−
Gate to source withstand voltage ≥
Charger voltage^*3
Resistance should be as small as
R1, R2 Resistor
ESD protection,
For power fluctuation
470 Ω
150 Ω^*1
1 kΩ^*1
possible to avoid lowering the
overcharge detection accuracy due to
current consumption.^*4
C1, C2 Capacitor For power fluctuation
0.1 μF
0.068 μF^*1
1.0 μF^*1
Connect a capacitor of 0.068 μF or
higher between VDD pin and VSS pin.^*5
Protection for reverse
Select as large a resistance as possible
R3
Resistor connection of a
2 kΩ
300 Ω^*1
4 kΩ^*1 to prevent current when a charger is
charger
connected in reverse.^*6
*1. Please set up a filter constant to be R1 × C1 = R2 × C2.
*2. If the threshold voltage of an FET is low, the FET may not cut the charge 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.
*3. If the withstand voltage between the gate and source is equal to or lower than the charger voltage, the FET may be
destroyed.
*4. An accuracy of overcharge detection voltage is guaranteed by R1 = 470 Ω. Connecting resistors with other values
worsen the accuracy. In case of connecting larger resistor to R1, the voltage between the VDD pin and VSS pin may
exceed the absolute maximum rating because the current flows to the S-8252 Series from the charger due to reverse
connection of charger. Connect a resistor of 150 Ω or more to R1 for ESD protection.
*5. When connecting a resistor of 150 Ω or less to R1 or R2 or a capacitor of 0.068 μF or less to C1 or C2, the S-8252
Series may malfunction when power dissipation is largely fluctuated.
*6. When a resistor of 4 kΩ or more is connected to R3, the charge 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.
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