TLC352_16 Datasheet, PDF (5/18 Pages) Texas Instruments – LinCMOSE DUAL DIFFERENTIAL COMPARATOR

TLC352
LinCMOS DUAL DIFFERENTIAL COMPARATOR
SLCS016A − SEPTEMBER 1985 − REVISED SEPTEMBER 2002
PARAMETER MEASUREMENT INFORMATION
The digital output stage of the TLC352 can be damaged if it is held in the linear region of the transfer curve.
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 alternative for measuring parameters such as input offset voltage, common-mode rejection, etc., are
offered.
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 can
be slewed as shown in Figure 1(b) for the V_ICR test, rather than changing the input voltages, to provide greater
accuracy.
A close approximation of the input offset voltage can be obtained by using a binary search method to vary the
differential input voltage while monitoring the output state. When the applied input voltage differential is equal but
opposite in polarity to the input offset voltage, the output changes state.
5V
1V
+
−
Applied VIO
Limit
5.1 kΩ
VO
+
−
Applied VIO
Limit
5.1 kΩ
VO
−4V
(a) VIO WITH VIC = 0
(b) VIO WITH VIC = 4 V
Figure 1. Method for Verifying That Input Offset Voltage Is Within Specified Limits
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