S-8241 Seiko Instruments, S-8241 Datasheet - Page 13

• Manufacturer Part Number: S-8241
• Description: Battery Protection IC for 1-Cell Pack
• Manufacturer: Seiko Instruments

Rev.4.1
Remark Refer to the “
Normal Condition
Overcurrent Condition
Operation
The S-8241 monitors the voltage of the battery connected to VDD and VSS pins and the voltage difference
between VM and VSS pins to control charging and discharging. When the battery voltage is in the range
from the overdischarge detection voltage (V
voltage is in the range from the charger detection voltage (V
(V
the charging and discharging control FETs on. This condition is called normal condition and in this condition
charging and discharging can be carried out freely.
When the discharging current becomes equal to or higher than a specified value (the VM pin voltage is
equal to or higher than the overcurrent detection voltage) during discharging under normal condition and
the state continues for the overcurrent detection delay time or longer, the S-8241 turns the discharging
control FET off to stop discharging. This condition is called overcurrent condition. (The overcurrent
includes overcurrent 1, overcurrent 2, or load short-circuiting.)
The VM and VSS pins are shorted internally by the R
load is connected, the VM pin voltage equals the V
The overcurrent condition returns to the normal condition when the load is released and the impedance
between the EB+ and EB- pins (see the figure 10 for a connection example) becomes higher than the
automatic recoverable impedance (see the equation [1] below). When the load is removed, the VM pin
goes back to the V
the VM pin potential is lower than the overcurrent 1 detection voltage (V
condition.
Automatic recoverable impedance = {Battery voltage / (Minimum value of overcurrent 1 detection voltage) -
1} x (R
Example: Battery voltage = 3.5 V and overcurrent 1 detection voltage (V
Automatic recoverable impedance = (3.5 V / 0.07 V -1) x 200 kΩ = 9.8 MΩ
Remark The automatic recoverable impedance varies with the battery voltage and overcurrent 1 detection voltage
IOV1
_01
) (the current flowing through the battery is equal to or lower than a specified value), the IC turns both
VMS
settings. Determine the minimum value of the open load using the above equation [1] to have automatic
recovery from the overcurrent condition work after checking the overcurrent 1 detection voltage setting for the
IC.
maximum value) --- [1]
SS
potential since the VM pin is shorted the VSS pin with the R
Battery Protection IC Connection Example”.
Seiko Instruments Inc.
DL
BATTERY PROTECTION IC FOR 1-CELL PACK
) to the overcharge detection voltage (V
DD
VMS
voltage due to the load.
resistor under the overcurrent condition. When a
CHA
) to the overcurrent 1 detection voltage
IOV1
IOV1
), the IC returns to the normal
) = 0.1 V
VMS
resistor. Detecting that
CU
S-8241 Series
), and the VM pin
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