S-8261ABRMD-G3RT2G Datasheet, PDF (18/33 Pages) List of Unclassifed Manufacturers – BATTERY PROTECTION IC FOR 1-CELL PACK

BATTERY PROTECTION IC FOR 1-CELL PACK
S-8261 Series
Rev.5.3_00
„ Operation
Remark Refer to “„ Battery Protection IC Connection Example”.
1. Normal Status
The S-8261 Series monitors the voltage of the battery connected between VDD pin and VSS pin and the voltage
difference between VM pin and VSS pin to control charging and discharging. When the battery voltage is in the
range from the overdischarge detection voltage (V_DL) to the overcharge detection voltage (V_CU), and the VM pin
voltage is in the range from the charger detection voltage (V_CHA) to the overcurrent 1 detection voltage (V_IOV1), the IC
turns both the charging and discharging control FETs on. This status is called the normal status, and in this status
charging and discharging can be carried out freely.
Caution When a battery is connected to the IC for the first time, discharging may not be enabled. In this
case, short the VM pin and VSS pin or connect the charger to restore the normal condition.
2. Overcurrent Status (Detection of Overcurrent 1, Overcurrent 2 and Load Short-circuiting)
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 completely, the VM pin returns to the V_SS potential.
The voltage of the VM pin returns to overcurrent 1 detection voltage (V_IOV1) or lower and the overcurrent status is
restored to the normal status.
3. Overcharge Status
When the battery voltage becomes higher than the overcharge detection voltage (V_CU) during charging under the
normal status and the detection continues for the overcharge detection delay time (t_CU) or longer, the S-8261 Series
turns the charging control FET off to stop charging. This status is called the overcharge status.
The overcharge status is released by the following two cases ((1) and (2)):
(1) When the battery voltage falls below the overcharge release voltage (V_CU) − overcharge detection hysteresis
voltage (V_HC), the S-8261 Series turns the charging control FET on and turns to the normal status.
(2) When a load is connected and discharging starts, the S-8261 Series turns the charging control FET on and
returns to the normal status. Just after the load is connected and discharging starts, the discharging current flows
through the parasitic diode in the charging control FET. At this moment the VM pin potential becomes V_f, the
voltage for the parasitic diode, higher than V_SS level. When the battery voltage goes under the overcharge
detection voltage (V_CU) and provided that the VM pin voltage is higher than the overcurrent 1 detection voltage,
the S-8261 Series releases the overcharge status.
Caution 1. If the battery is charged to a voltage higher than the overcharge detection voltage (V_CU) and the
battery voltage does not fall below the overcharge detection voltage (V_CU) even when a heavy load
is connected, the detection of overcurrent 1, overcurrent 2 and load short-circuiting do not
function until the battery voltage falls below overcharge detection voltage (V_CU). Since an actual
battery has an internal impedance of several dozens of mΩ, the battery voltage drops immediately
after a heavy load that causes overcurrent is connected, and the detection of overcurrent 1,
overcurrent 2 and load short-circuiting function.
2. When a charger is connected after the overcharge detection, the overcharge status is not
released even if the battery voltage is below the overcharge release voltage (V_CL). The
overcharge status is released when the VM pin voltage goes over the charger detection voltage
(V_CHA) by removing the charger.
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Seiko Instruments Inc.