ITT - Index of

GENERAL INFORMATION ITT54H/74H SERIES TTL FAMILY
Note 7
For all devices not more than one output to be
shorted at any time. Open collector devices; no
parameter for -ISC.
Note 8
Typic,!I limits are at ambient temperature. T A
25°C and VCC = 5V.
A.C. TESTS
Testing of propagation delays is carried out using
the typical switching load circuits shown below.
These load circuits are designed to simulate full fanout
loading. An oscilloscope with high impedance
probes and having a bandwidth of at least 100 MHz
is suitable for these measurements.
TYPICAL SWITCHING TEST LOAD CIRCUITS
For totem pole outputs:
DEVICEO'P
'~O-~-'~"~~~~~IM~IM----~
Diodes are type 1 N4148 or equiv.
The values of CL and RL are quoted in the data
sheets. Value of CL includes probe and jig
capitance.
The characteristics of the pulse generator used at
the input of the device are stated in the data sheets.
Typical characteristics are: VOUT = 3V; Rise time.
tr. = Fall time. tf. = less than 7 ns; Zo = 50; Pulse
Repetition Frequency. P.R.F. = 1 MHz; Pulse width
for gate. tp = 500 ns.
Waveforms
BV /.-------\INPUT
I . I
I . I k- '•.-.j
I I
I I I ;.. -~-- ___ _-,90,),.
50%
"5V~\-----~PUT + -- t 10%
I I I I I II
'~ \.- -.j ~+ -tt"r-1'0f4-
CIRCUIT DIAGRAM ITT74HOO GATE
r-----~~---------1~VCC
OUTPUT
For open collector outputs:
OEYICE'~/P, RL Yee
I C
~ ,
-..
L
OUTPUT
I ,
1\
I,
470!l.
4kfi
GND
COMPONENT VAWES ARE NOMINAL
The d.c. operation of this circuit is more readfly
understood if the multiemitter transistor (M ET) connecting
the inputs is considered equivalent to a
diode AND gate in series with an offset diode connected
to the base of transistor VTl. This is shown
in Fig. 2. the emitter-base junctions of the MET
forming the input diodes and the collector base
junction forming' the offs~t diode.