S-8225AAA-TCT1U Datasheet, PDF (12/26 Pages) Seiko Instruments Inc – BATTERY MONITORING IC

BATTERY MONITORING IC FOR 3-SERIAL TO 5-SERIAL CELL PACK
S-8225A Series
Rev.1.7_02
5. 0 V battery detection function
In the S-8225A Series, users are able to select a 0 V battery detection "available" function.
If this optional function is selected, the CO pin becomes detection status when the voltage of one of the batteries
becomes 0 V battery detection voltage (V0INHn) or lower.
6. Delay time setting
When the voltage of one of the batteries becomes VCUn or higher, the S-8225A Series charges the capacitor
connected to the CCT pin rapidly up to the CCT pin voltage (VCCT). After that, The S-8225A Series discharges the
capacitor with the constant current of 100 nA, and the CO pin output is defined as detection status at the time when
the CCT pin voltage falls to a certain level or lower. The overcharge detection delay time (tCU) changes depending on
the capacitor connected to the CCT pin.
tCU is calculated by the following formula.
Min. Typ. Max.
tCU [s] = (6.7, 10, 13.3) × CCCT [μF]
Similarly, the overdischarge detection delay time (tDL) changes depending on the capacitor connected to the CDT pin.
tDL is calculated by the following formula.
Min. Typ. Max.
tDL [s] = (6.7, 10, 13.3) × CCDT [μF]
Since the S-8225A Series charges the capacitor for delay rapidly, the voltage of the CCT pin and the CDT pin
becomes large if the capacitance value is small. As a result, a variation between the calculated value of the delay
time and the actual delay time is generated.
If the capacitance value is so large that the rapid charging can not be finished within the internal delay time, the
output pin becomes detection status simultaneously with the end of internal delay time.
In addition, the charging current to the capacitor for delay passes through the VDD pin. Therefore, a large resistor
connected to the VDD pin results in a big drop of the power supply voltage at the time of rapid charging which causes
malfunction.
Regarding the recommended values for external components, refer to "Table 9 Constants for External
Components".
7. SEL pin
In the S-8225A Series, switchable monitoring control between 3-cell to 5-cell is possible by using the SEL1 pin and
the SEL2 pin. For example, since the overdischarge detection of V4 or V5 is prohibited and the overdischarge is not
detected even if V4 or V5 is shorted when the SEL1 pin is "H" and the SEL2 pin is "L", the S-8225A Series can be
used for 3-cell monitoring.
Be sure to use the SEL1 pin and the SEL2 pin at "H" or "L" potential.
Table 8 Settings of SEL1 Pin and SEL2 Pin
SEL1 pin
SEL2 pin
"H"^*1
"H"^*1
"H"^*1
"L"^*2
"L"^*2
"H"^*1
"L"^*2
"L"^*2
*1. "H": SEL1 ≥ VSELH1 and SEL2 ≥ VSELH2
*2. "L": SEL1 ≤ VSELL1 and SEL2 ≤ VSELL2
Setting
Prohibition
3-cell monitoring
4-cell monitoring
5-cell monitoring
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