HY2120
2-Cell Lithium-ion/Lithium Polymer Battery Packs Protection ICs
11. Description of Operation
11.1.Normal Status
This IC monitors the voltage of the battery connected between the VDD pin and VSS pin and the
voltage difference between the CS pin and VSS pin to control charging and discharging.
When the cell1 and cell2 voltage is in the range from overdischarge detection voltage (VDLn) to
overcharge detection voltage (VCUn), and the CS pin voltage is in the range from the charge
overcurrent detection voltage (VCIP) to discharge overcurrent detection voltage (VDIP), the IC turns
both the charging and discharging control MOSFET on. This condition is called the normal status.
Under this condition, charging and discharging can both be carried out freely.
Notice: Discharging may not be enacted when the battery is first time connected. To regain
normal status, CS and VSS PIN must be shorted or the charger must be connected.
11.2.Overcharge Status
11.2.1 Overcharge release code 1 model
The normal state of the battery voltage between VDD pin and VC pin (the voltage of Cell 1) and the
voltage between VC pin and VSS pin (the voltage of Cell2), if either voltage becomes equal or more
than the overcharge detector voltage (VCUn), and continued exceed overcharge delay time (TOC) an
external charge control Nch MOSFET turns off with OC pin being at "L" level.
.
To reset the overcharge and make the OC pin level to "H" again after detecting overcharge, in such
conditions that a time when the both Cell1 and Cell2 are down to a level lower than overcharge
voltage, by connecting a kind of load to VDD after disconnecting a charger from the battery pack.
Then, the output voltage of OC pin becomes "H", and it makes an external Nch MOSFET turn on,
and charge cycle is available. In other words, once overcharge is detected, even if the supply
voltage becomes low enough, if a charger is continuously connected to the battery pack, recharge is
not possible.
11.2.2 Overcharge release code 2 model
The normal state of the battery voltage between VDD pin and VC pin (the voltage of Cell 1) and the
voltage between VC pin and VSS pin (the voltage of Cell2), if either voltage becomes equal or more
than the overcharge detector voltage (VCUn), and continued exceed overcharge delay time (TOC) an
external charge control Nch MOSFET turns off with OC pin being at "L" level.
The overcharge status can be release by the following two cases:
(1) The voltage of the battery cell1 and the voltage of the battery cell2 are equal to or lowers than the
overcharge release voltage (VCRn) due to self-discharge.
(2) When load is connected and the battery voltage falls below the overcharge protection voltage
(VCUn).
Notice:
Further, either or both voltage of Cell1 and Cell2 is higher than the overcharge detector threshold, if
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