7106

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

10 of 18

www.unisonic.com.tw

QW-R502-018.D

DETAILED DESCRIPTION(Cont.)

TEST

The TEST pin serves two function. On the UTC 7106 it is coupled to the internally generated digital supply through

a 500Ω resistor. Thus it can be used as the negative supply for externally generated segment drivers such as

decimal points or any other presentation the user may want to include on the LCD display. Figures 3 and 4 show

such an application. No more than a 1mA load should be applied.

The second function is a “lamp test”. When TEST is pulled high (to V+) all segments will be turned on and the

display should read ”1888”. The TEST pin will sink about 15mA under these conditions.

CAUTION: In the lamp test mode, the segments have a constant DC voltage (no square-wave) . This may burn the

LCD display if maintained for extended periods.