S-8242B Datasheet, PDF (11/30 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
3. Overdischarge Status
When the battery voltage falls below overdischarge detection voltage n (V_DLn) during discharging in the normal status
and detection continues for the overdischarge detection delay time (t_DL) or longer, the S-8242B Series turns the
discharging control FET off to stop discharging. This condition is called the overdischarge status. When the
discharging control FET is turned off, the VM pin voltage is pulled up by the resistor between the VM and VDD pins in
the IC (R_VMD). When the voltage difference between the VM and VDD pins then is 1.3 V (typ.) or lower, the current
consumption is reduced to the power-down current consumption (I_PDN). This condition is called the power-down
status.
The power-down status is released when a charger is connected and the voltage difference between the VM and
VDD pins becomes 1.3 V (typ.) or higher. Moreover, when the battery voltage becomes overdischarge detection
voltage n (V_DLn) or higher, the S-8242B Series turns the discharging FET on and returns to the normal status.
4. Charger Detection
When a battery in the overdischarge status is connected to a charger and provided that the VM pin voltage is lower
than the charger detection voltage (V_CHA), the overdischarge hysteresis is released via the charge detection function;
therefore, the S-8242B Series releases the overdischarge status and turns the discharging control FET on when the
battery voltage becomes equal to or higher than overdischarge detection voltage n (V_DLn) since the charger detection
function works. This action is called charger detection.
When a battery in the overdischarge status is connected to a charger and provided that the VM pin voltage is not
lower than the charger detection voltage (V_CHA), the S-8242B Series releases the overdischarge status when the
battery voltage reaches overdischarge release voltage n (V_DUn) or higher.
5. Overcurrent Status
When a battery in the normal status is in the status where the voltage of the VM pin is equal to or higher than the
overcurrent detection voltage because the discharge current is higher than the specified value and the status lasts for
the overcurrent detection delay time, the discharge control FET is turned off and discharging is stopped. This status
is called the overcurrent status.
In the overcurrent status, the VM and VSS pins are shorted by the resistor between VM and VSS (R_VMS) in the IC.
However, the voltage of the VM pin is at the V_DD potential due to the load as long as the load is connected. When the
load is disconnected, the VM pin returns to the V_SS potential.
This IC detects the status when the impedance between the EB+ pin and EB− pin (Refer to Figure 13) increases and
is equal to the impedance that enables automatic restoration and the voltage at the VM pin returns to overcurrent
detection voltage 1 (V_IOV1) or lower and the overcurrent status is restored to the normal status.
Caution The impedance that enables automatic restoration varies depending on the battery voltage and the
set value of overcurrent detection voltage 1.
Seiko Instruments Inc.
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