6

Test Circuits and Waveforms

FIGURE 1. HC AND HCU TRANSITION TIMES AND PROPAGA-

TION DELAY TIMES, COMBINATION LOGIC

FIGURE 2. HCT TRANSITION TIMES AND PROPAGATION

DELAY TIMES, COMBINATION LOGIC

tPHL

tPLH

tTHL

tTLH

90%

50%

10%

50%

10%

INVERTING

OUTPUT

INPUT

GND

VCC

tr = 6ns

tf = 6ns

90%

tPHL

tPLH

tTHL

tTLH

2.7V

1.3V

0.3V

1.3V

10%

INVERTING

OUTPUT

INPUT

GND

3V

tr = 6ns

tf = 6ns

90%

CD54/74HC157, CD54/74HCT157, CD54/74HC158, CD54/74HCT158