S-82B1AAA-I6T1U Datasheet, PDF (14/35 Pages) Seiko Instruments Inc – High-accuracy voltage detection circuit

BATTERY PROTECTION IC WITH CHARGE-DISCHARGE CONTROL FUNCTION FOR 1-CELL PACK
S-82B1A Series
Rev.1.1_00
 Operation
Remark Refer to " Battery Protection IC Connection Example".
1. Normal status
The S-82B1A Series monitors the voltage of the battery connected between VDD pin and VSS pin, the voltage between
VM pin and VSS pin and the voltage between CTL pin and VSS pin to control charging and discharging.
1. 1 CTL pin control logic active "H"
When the battery voltage is in the range from overdischarge detection voltage (V_DL) to overcharge detection voltage
(V_CU), the VM pin voltage is in the range from charge overcurrent detection voltage (V_CIOV) to discharge overcurrent
detection voltage 1 (V_DIOV1), and the CTL pin voltage is equal to or lower than the CTL pin voltage "L" (V_CTLL), the
S-82B1A Series turns both the charge-discharge control FETs on. This condition is called the normal status, and in
this condition charging and discharging can be carried out freely.
The resistance between VDD pin and VM pin (R_VMD), and the resistance between VM pin and VSS pin (R_VMS) are
not connected in the normal status.
1. 2 CTL pin control logic active "L"
When the battery voltage is in the range from overdischarge detection voltage (V_DL) to overcharge detection voltage
(V_CU), the VM pin voltage is in the range from charge overcurrent detection voltage (V_CIOV) to discharge overcurrent
detection voltage 1 (V_DIOV1), and the CTL pin voltage is equal to or higher than the CTL pin voltage "H" (V_CTLH), the
S-82B1A Series turns both the charge-discharge control FETs on. This condition is called the normal status, and in
this condition charging and discharging can be carried out freely.
The resistance between VDD pin and VM pin (R_VMD), and the resistance between VM pin and VSS pin (R_VMS) are
not connected in the normal status.
Caution When the battery is connected for the first time, discharge may not be carried. In this case, short the
VM pin and VSS pin, or set the VM pin voltage at the level of V_CIOV or higher and at the level of V_DIOV1 or
lower by connecting the charger. The S-82B1A Series then becomes the normal status.
2. Overcharge status
2. 1 V_CL ≠ V_CU (Product in which overcharge release voltage differs from overcharge detection voltage)
When the battery voltage becomes higher than V_CU during charging in the normal status and the condition continues
for the overcharge detection delay time (t_CU) or longer, the S-82B1A Series turns the charge control FET off to stop
charging. This condition is called the overcharge status.
The overcharge status is released in the following two cases.
(1) In the case that the VM pin voltage is lower than 0.35 V typ., the S-82B1A Series releases the overcharge status
when the battery voltage falls below overcharge release voltage (V_CL).
(2) In the case that the VM pin voltage is equal to or higher than 0.35 V typ., the S-82B1A Series releases the
overcharge status when the battery voltage falls below V_CU.
When the discharge is started by connecting a load after the overcharge detection, the VM pin voltage rises by the V_f
voltage of the parasitic diode than the VSS pin voltage, because the discharge current flows through the parasitic
diode in the charge control FET. If this VM pin voltage is equal to or higher than 0.35 V typ., the S-82B1A Series
releases the overcharge status when the battery voltage is equal to or lower than V_CU.
Caution
If the battery is charged to a voltage higher than V_CU and the battery voltage does not fall below V_CU
even when a heavy load is connected, discharge overcurrent detection and load short-circuiting
detection do not function until the battery voltage falls below V_CU. Since an actual battery has an
internal impedance of tens of mΩ, the battery voltage drops immediately after a heavy load that
causes overcurrent is connected, and discharge overcurrent detection and load short-circuiting
detection function.
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