UB2012

Preliminary

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

10 of 17

www.unisonic.com.tw

QW-R121-018 .C

APPLICATION INFORMATION(Cont.)

VOLTAGE REGULATION PHASE

The voltage regulation feedback is through the BAT pin. This input is tied directly to the positive side of the

battery pack. The UTC UB2012 monitors the battery-pack voltage between the BAT and VSS pins. According to the

voltage regulation, there are four versions of UTC UB2012, namely, 4.1V, 4.2V, 8.2V and 8.4V.

Other regulation voltages can be achieved by adding a voltage divider between the positive and negative

terminals of the battery pack and using UTC UB2012C or UTC UB2012D. The voltage divider presents scaled

battery-pack voltage to BAT input. (See Fig. 7, 8) The resistor values RB1 and RB2 for the voltage divider are

calculated by the following equation:

1

-

)

V

V

×

(N

=

R

R

O(REG)

(CELL)

B2

B1

(2)

CHARGE TERMINATION AND RECHARGE

The UTC UB2012 monitors the charging current during the voltage-regulation phase. The UTC UB2012

declares a done condition and terminates charge when the current tapers off to the charge termination threshold,