S-8205AAA-TCT1U Datasheet, PDF (17/33 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC

Rev.1.9_00
BATTERY PROTECTION IC FOR 4-SERIES OR 5-SERIES CELL PACK
S-8205A/B Series
5. Charge Overcurrent Status
In the S-8205A/B Series, the charge current increases to a certain value or more. As a result, if the status in which
the VINI pin voltage decreases to the level of V_CIOV or less, the CO pin is set in high impedance. This is the charge
overcurrent status. The charge control FET is turned off and it stops charging. In this charge overcurrent status, DO
pin gets the V_SS level. The VM pin is pulled up to the V_DD level by resistance between VM pin and VDD pin (R_VMD).
The charge overcurrent status is released if the following condition is satisfied.
(1) The CO pin voltage gets 1 / 50 × V_DS (typ.) or more.
6. 0 V Battery Charge Function
In the S-8205A/B Series, regarding how to charge a discharged battery (0 V battery), users are able to select either
function mentioned below.
(1) Enable to charge a 0 V battery
A 0 V battery is charged when charger voltage is more than 0 V battery charge starting charger voltage
(V_0CHA).
(2) Inhibit charging a 0 V battery
A 0 V battery is not charged when the voltage of one of the batteries is 0 V battery charge inhibition battery
voltage (V_0INH) or less.
Caution When the VDD pin voltage is less than the minimum value of operation voltage between VDD pin
and VSS pin (V_DSOP), the S-8205A/B Series' action is not assured.
7. Delay Time Setting
In the S-8205A/B Series, users are able to set delay time for the period; from detecting the voltage of one of the
batteries or detecting changes in the voltage at the VINI pin, to the output to the CO pin, DO pin. Each delay time is
determined by a resistor in the IC and an external capacitor.
In the overchage detection, when the voltage of one of the batteries gets V_CUn or more, the S-8205A/B Series starts
charging to the CCT pin's capacitor (C_CCT) via the CCT pin's internal resistor (R_CCT). After a certain period, the CO pin
is set in high impedance if the voltage at the CCT pin reaches the CCT pin detection voltage (V_CCT). This period is
overcharge detection delay time (t_CU).
t_CU is calculated using the following equation (V_DS = V1 + V2 + V3 + V4 + V5).
t_CU [s] = −ln ( 1 − V_CCT / V_DS ) × C_CCT [μF] × R_CCT [MΩ]
= −ln ( 1 − 0.7 (typ.)) × C_CCT [μF] × 8.31 [MΩ] (typ.)
= 10.0 [MΩ] (typ.) × C_CCT [μF]
Overdischarge detection delay time (t_DL), discharge overcurrent detection delay time (t_DIOV), charge overcurrent
detection delay time (t_CIOV) are calculated using the following equations as well.
t_DL [ms] = −ln ( 1 − V_CDT / V_DS) × C_CDT [μF] × R_CDT [kΩ]
t_DIOV [ms] = −ln ( 1 − V_CIT / V_DS) × C_CIT [μF] × R_CIT [kΩ]
t_CIOV [ms] = −ln ( 1 − V_CIT / V_DS) × C_CIT [μF] × R_CIT [kΩ]
In case C_CCT = C_CDT = C_CIT = 0.1 [μF], each delay time t_CU, t_DL, t_DIOV, t_CIOV is calculated as follows.
t_CU [s] = 10.0 [MΩ] (typ.) × 0.1 [μF] = 1.0 [s] (typ.)
t_DL [ms] = 1000 [kΩ] (typ.) × 0.1 [μF] = 100 [ms] (typ.)
t_DIOV [ms] = 200 [kΩ] (typ.) × 0.1 [μF] = 20 [ms] (typ.)
t_CIOV [ms] = 200 [kΩ] (typ.) × 0.1 [μF] = 20 [ms] (typ.)
Discharge overcurrent release delay time (t_DIOVR) and charge overcurrent release delay time (t_CIOVR) can be selected
from two types, and they are calculated by t_DIOV and t_CIOV as the following equations. 1 [ms] (typ.) is the internal delay
time of the S-8205A/B Series.
(1) t_DIOVR = t_DIOV × 10 + 1 [ms] (typ.), t_CIOVR = t_CIOV × 10 + 1 [ms] (typ.)
(2) t_DIOVR = t_DIOV × 0.05 + 1 [ms] (typ.), t_CIOVR = t_CIOV × 0.05 + 1 [ms] (typ.)
Load short circuit detection delay time (t_SHORT) is fixed internally.
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