UB261G-AB-AG6-R datasheet(6/10 Pages) UTC

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UB261

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

6 of 10

www.unisonic.com.tw

QW-R502-A27.b



OPERATION(Cont.)

4. Overdischarge Condition

When the battery voltage falls below the overdischarge detection voltage (VDL) during discharging under the

normal condition and the detection continues for the overdischarge detection delay time (tDL), the UTC UB261 series

turns the discharging control FET off to stop discharging. This condition is called the overdischarge condition. When

the discharging control FET is turned off, the VM pin voltage is pulled up by the resistor between VM and VDD in the IC

(RVMD). When the voltage difference between the VM and VDD then is 1.2V (typ.) or lower, the current consumption is

reduced to the power-down current consumption (IPDN). This condition is called the power-down condition.

The power-down condition is released when a charger is connected and the voltage difference between the VM

and VDD becomes 1.2V (typ.) or higher. Moreover when the battery voltage becomes the overdischarge detection

voltage (VDL) or higher, the UTC UB261 series turns the discharging FET on and returns to the normal condition.

5. Charger Detection

When a battery in the overdischarge condition is connected to a charger and provided that the VM pin voltage is

lower than the charger detection voltage (VCHA), the UTC UB261 series releases the overdischarge condition and

turns the discharging control FET on when the battery voltage becomes equal to or higher than the overdischarge

detection voltage (VDL) since the charger detection function works. This action is called charger detection.

When a battery in the overdischarge condition is connected to a charger and provided that the VM pin voltage is

not lower than the charger detection voltage (VCHA), the UTC UB261 series releases the overdischarge condition

when the battery voltage reaches the overdischarge detection voltage (VDU) or higher.

6. Abnormal Charge Current Detection

If the VM pin voltage falls below the charger detection voltage (VCHA) during charging under normal condition and it

continues for the overcharge detection delay time (tCU) , the charging control FET turns off and charging stops. This

action is called the abnormal charge current detection.

Abnormal charge current detection works when the DO pin voltage is “H” and the VM pin voltage falls below the

charger detection voltage (VCHA). Consequently, if an abnormal charge current flows to an over-discharged battery,

the UTC UB261 series turns the charging control FET off and stops charging after the battery voltage becomes

higher than the overdischarge detection voltage which make the DO pin voltage “H”, and still after the overcharge

detection delay time (tCU) elapses.

Abnormal charge current detection is released when the voltage difference between VM pin and VSS pin becomes

less than charger detection voltage (VCHA).

7. Delay Circuits

The detection delay times are determined by dividing a clock of the approximately 3.5kHz with the counter.

Note 1: The detection delay time for overcurrent 2 (tIOV2) and load short-circuiting (tSHORT) start when the

overcurrent 1 (VIOV1) is detected. When the overcurrent 2 (VIOV2) or load short-circuiting (VSHORT) is detected over the

detection delay time for each of them (= tIOV2 or tSHORT) after the detection of overcurrent 1 (VIOV1), the UTC UB261

series turns the FET off within tIOV2 or tSHORT of each detection.

Note 2: When the overcurrent is detected and continues for longer than the overdischarge detection delay time (tDL)

without releasing the load, the condition changes to the power-down condition when the battery voltage falls below

the overdischarge detection voltage (VDL). When the battery voltage falls below the overdischarge detection voltage

(VDL) due to the overcurrent, the UTC UB261 series turns the discharging control FET off by the overcurrent

detection. In this case the recovery of the battery voltage is so slow that if the battery voltage after the overdischarge

detection delay time (tDL) is still lower than the over discharge detection voltage (VDL), the UTC UB261 series shifts

to the power-down condition.

8. 0V Battery Charge Inhibiting Function

This function inhibits the recharging when a battery that is short-circuited (0V battery) internally is connected.

When the battery voltage is the 0V battery charge inhibition battery voltage (V0INH) or lower, the charging control FET

gate is fixed to EB- pin voltage to inhibit charging. When the battery voltage is the 0V battery charge inhibition

battery voltage (V0INH) or higher, charging can be performed.

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