TLC139, TLC339, TLC339Q

LinCMOS MICROPOWER QUAD COMPARATORS

9

WWW.TI.COM

PARAMETER MEASUREMENT INFORMATION

Propagation delay time is defined as the interval between the application of an input step function and the instant when

the output reaches 50% of its maximum value. Propagation delay time, low-to-high-level output, is measured from

the leading edge of the input pulse, while propagation delay time, high-to-low-level output, is measured from the

trailing edge of the input pulse. Propagation delay time measurement at low input signal levels can be greatly affected

by the input offset voltage. The offset voltage should be balanced by the adjustment at the inverting input as shown

in Figure 3, so that the circuit is just at the transition point. Then a low signal, for example 105-mV or 5-mV overdrive,

causes the output to change state.

90%

Pulse

Generator

VDD

DUT

TEST CIRCUIT

Input Offset Voltage

Compensation Adjustment

Low-to-High-Level

Output

VOLTAGE WAVEFORMS

High-to-Low-Level

Output

1

µF

5.1 k

Ω

50

Ω

1 k

Ω

1 V

−1 V

10

Ω

10 Turn

0.1

µF

CL

(see Note A)

Overdrive

Input

Overdrive

Input

100 mV

100 mV

50%

50%

10%

tPLH

tPHL

tTHL

NOTE A: CL includes probe and jig capacitance.

Figure 3. Propagation Delay, Rise, and Fall Times Test Circuit and Voltage Waveforms