ULC393

Preliminary

CMOS IC

UNISONIC TECHNOLOGIES CO., LTD

5 of 7

www.unisonic.com.tw

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PARAM ET ER M EASU REM EN T I N FORM AT I ON

The UTC ULC393 contains a digital output stage which, if held in the linear region of the transfer curve, can cause

damage to the device. Conventional operational amplifier/comparator testing incorporates the use of a servo loop

that is designed to force the device output to a level within this linear region. Since the servo-loop method of testing

cannot be used, the following alternatives for testing parameters such as input offset voltage, common-mode

rejection ratio, etc., are suggested.

To verify that the input offset voltage falls within the limits specified, the limit value is applied to the input as shown

in Figure 1(a). With the noninverting input positive with respect to the inverting input, the output should be high.

With the input polarity reversed, the output should be low.

A similar test can be made to verify the input offset voltage at the common-mode extremes. The supply voltages

accuracy.

+

-

Limit

5V

5.1k

Ω

Limit

+

-

1V

5.1k

Ω

-4V

Figure 1. Method for Verifying That Input Offset Voltage Is Within Specified Limits