74HC datasheet(16/19 Pages) PHILIPS

16 / 19 page

March 1988

Philips Semiconductors

HCMOS family characteristics

FAMILY SPECIFICATIONS

AC CHARACTERISTICS

The “AC CHARACTERISTICS” table lists the guaranteed

limits when a device is tested under the conditions given in

the AC Test Circuits and Waveforms section.

TEST CIRCUITS

Good high-frequency wiring practices should be used in

test circuits. Capacitor leads should be as short as

possible to minimize ripples on the output waveform

transitions and undershoot. Generous ground metal

(preferably a ground-plane) should be used for the same

reasons. A VCC decoupling capacitor should be provided

at the test socket, also with short leads. Input signals

should have rise and fall times of 6 ns, a signal swing of

0 V to VCC for 74HC and 0 V to 3 V for 74HCT; a 1.0 MHz

square wave is recommended for most propagation delay

tests. The repetition rate must be increased for testing

fmax. Two pulse generators are usually required for testing

such parameters as set-up time, hold time and removal

time. fmax is also tested with 6 ns input rise and fall times,

with a 50% duty factor, but for typical fmax as high as

60 MHz, there are no constraints on rise and fall times.

74HC 데이터시트(PDF) 16 Page - NXP Semiconductors