SC121
FUNCTION DESCRIPTIONS
Normal Status
If VODL<VDD<VOCU and VCH<VCSI<VOI1, M1 and M2 are both turned on (refer to Typical Application Circuits).
The charging and discharging processes can be operated normally.
Overcharge Detection
When enter charging from normal status, the battery voltage can be detected from VDD. When the battery is in
overcharge status, VDD is larger than VOCU over a delay time of TOC, M2 is to be turned off.
Release of Overcharge Status
There are two ways to return to normal status from overcharge status.
· If the battery is self discharging and VDD<VOCR occurs, M2 is to be turned on and back to normal status.
· Remove the charger and connected to a load. If VOCR<VDD<VOCU and VCSI>VOI1 occurs, M2 is to be turned
on and back to normal status.
Over discharge Detection
When enter discharging from normal status, the battery voltage can be detected from DVD. When the battery is
in over discharge status, DVD is smaller than VODL over a delay time of TOD; M1 is to be turned off. In the
meanwhile, CSI is pulled to VDD by way of internal resistor RCSID. If VCSI>VOI2, the protection IC enters into
Power•down mode. (Its current consumption is lower than 0.3mA).
Release of Power•down mode
A charger is connected while the battery remains in Power•down mode. If VCH<VCSI<VOI2 and VDD<VODR
occur, M1 is still off but it releases Power•down mode. If VDD>VODR occurs, M1 is to be turned on and back to
normal status.
Charger Detection
If a charger is connected to the battery remained in Power•down mode, the voltages will become VCSI<VCH
and VDD>VODL. M1 is to be turned on and back to normal status.
Abnormal Charging Status
If a charger is connected to the battery in normal status, VCSI<VCH occurs over a delay time longer than TOC,
M2 is to be turned off.
Over Current/Short Current Detection
When the discharging current is too large during discharging under normal status and the voltage detected
from CSI is larger than VOIX (VIO1 or VIO2) for over a certain delay time TOIX (TIO1 or TIO2), it means the over
current/short current status occurred. M1 is turned off. CSI is pulled to VSS by way of an internal resistor RCSIS.
Release of Over Current/Short Current Status
While the protection IC remains in Over Current/Short Current status and load is removed or the impedance
between VBAT+ and VBAT• is larger than 500KW and VCSI<VOI1, M1 is to be turned on and back to normal status.
Note: when a battery is connected to a protection IC for the first time, the IC may not enter the normal status (not
dischargeable status). If this occurs, set the CSI pin voltage equal to the V voltage (short the CSI and
SS
V
SS
pins or connect a charger) to enter the normal status.
HANGZHOU MICROELECTRONICS CO.,LTD
Http:// www.silan.com.cn
REV:1.6
2009.07.20
Page 4 of 9
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