UB211CG-AA-AF5-R datasheet(6/10 Pages) UTC

6 / 10 page

UB211C

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

6 of 10

www.unisonic.com.tw

QW-R502-482.d



OPERATION (Cont.)

4. Discharge Overcurrent Condition (Discharge Overcurrent, Load Short-circuiting)

When a battery in the normal condition is in the status where the voltage of the VM pin is equal to or higher than

the discharge overcurrent detection voltage because the discharge current is higher than the specified value and the

status lasts for the discharge overcurrent detection delay time, the discharge control FET is turned off and

discharging is stopped. This status is called the discharge overcurrent condition.

In the discharge overcurrent condition, the VM pin and VSS pin are shorted by the resistor between VM pin and

VSS pin (RVMS) in the IC. However, the voltage of the VM pin is at the VDD potential due to the load as long as the load

is connected. When the load is disconnected, the VM pin returns to the VSS potential.

This IC detects the condition when the impedance between the EB+ pin and EB− pin (Refer to the typical

application circuit

) increases and is equal to the impedance that enables automatic restoration and the voltage at

the VM pin returns to discharge overcurrent detection voltage (VDIOV) or lower, the discharge overcurrent condition is

restored to the normal condition.

Even if the connected impedance is smaller than automatic restoration level, the UTC UB211C Series will be

restored to the normal status from discharge overcurrent detection status when the voltage at the VM pin becomes

the discharge overcurrent detection voltage (VDIOV) or lower by connecting the charger.

The resistance (RVMD) between the VM pin and VDD pin is not connected in the discharge overcurrent detection

condition.

5. Charge Overcurrent Condition

When a battery in the normal status is in the status where the voltage of the VM pin is lower than the charge

overcurrent detection voltage because the charge current is higher than the specified value and the status lasts for

the charge overcurrent detection delay time, the charge control FET is turned off and charging is stopped. This

status is called the charge overcurrent status.

This IC will be restored to the normal status from the charge overcurrent status when, the voltage at the VM pin

returns to charge overcurrent detection voltage (VCIOV) or higher by removing the charger.

The charge overcurrent detection function does not work in the overdischarge status.

The resistance (RVMD) between the VM pin and VDD pin, and the resistance (RVMS) between the VM pin and

VSS pin are not connected in the charge overcurrent status.

6. 0 V Battery Charging Function “Unavailable”

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

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

FET gate is fixed to the EB− pin (Refer to the typical application circuit) voltage to inhibit charging. When the

battery voltage is the 0 V battery charge inhibition battery voltage (V0INH) or higher, charging can be performed.

Caution Some battery providers do not recommend charging for a completely self-discharged battery. Please

ask the battery provider to determine whether to enable or inhibit the 0 V battery charging function.

7. Delay Circuit

(1) The discharge overcurrent detection delay time (tDIOV) and the load short-circuiting detection delay time

(tSHORT) start when the discharge overcurrent detection voltage (VDIOV) is detected. When the load shortcircuiting

detection voltage (VSHORT) is detected over the load short-circuiting detection delay time (tSHORT) after the detection of

discharge overcurrent detection voltage (VDIOV), the UTC UB211C turns the discharging control FET off within tSHORT

from the time of detecting VSHORT.

(2) When any overcurrent is detected and the overcurrent continues for longer than the overdischarge detection

delay time (tDL) without the load being released, the status changes to the power-down status at the point where the

battery voltage falls below overdischarge detection voltage (VDL).

(3) When the battery voltage falls below overdischarge detection voltage (VDL) due to overcurrent, the UTC

UB211C

Series turns the discharging control FET off via overcurrent detection. In this case, if the recovery of the

battery voltage is so slow that the battery voltage after the overdischarge detection delay time is still lower than the

overdischarge detection voltage, UTC UB211C Series shifts to the power-down status.

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