Datasheet
SCHS275E − MARCH 2002 − REVISED OCTOBER 2003
18
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION − ’HCT191
Test
Point
From Output
Under Test
C
L
(see Note A)
V
CC
S1
S2
LOAD CIRCUIT
PARAMETER
t
PZH
t
pd
or t
t
t
dis
t
en
t
PZL
t
PHZ
t
PLZ
Open Closed
S1
Closed Open
S2
Open Closed
Closed Open
Open Open
NOTES: A. C
L
includes probe and test-fixture capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.
C. Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators having the following
characteristics: PRR ≤ 1 MHz, Z
O
= 50 Ω, t
r
= 6 ns, t
f
= 6 ns.
D. For clock inputs, f
max
is measured with the input duty cycle at 50%.
E. The outputs are measured one at a time with one input transition per measurement.
F. t
PLZ
and t
PHZ
are the same as t
dis
.
G. t
PZL
and t
PZH
are the same as t
en
.
H. t
PLH
and t
PHL
are the same as t
pd
.
R
L
= 1 kΩ
VOLTAGE WAVEFORMS
SETUP AND HOLD AND INPUT RISE AND FALL TIMES
t
h
t
su
50% V
CC
50% V
CC
50%
10%10%
90% 90%
V
CC
V
CC
0 V
0 V
t
r
t
f
Reference
Input
Data
Input
VOLTAGE WAVEFORMS
PROPAGATION DELAY AND OUTPUT TRANSITION TIMES
50% V
CC
50% V
CC
50%
10%10%
90% 90%
V
CC
V
OH
V
OL
0 V
t
r
t
f
Input
In-Phase
Output
50% V
CC
t
PLH
t
PHL
50% V
CC
50%
10% 10%
90%90%
V
OH
V
OL
t
r
t
f
t
PHL
t
PLH
Out-of-Phase
Output
0 V
t
w
VOLTAGE WAVEFORMS
PULSE DURATION
Input
50% V
CC
50% V
CC
V
CC
Output
Control
Output
Waveform 1
(see Note B)
Output
Waveform 2
(see Note B)
V
OL
V
OH
t
PZL
t
PZH
t
PLZ
t
PHZ
≈V
C
C
0 V
50% V
CC
10%
50% V
CC
≈0 V
VOLTAGE WAVEFORMS
OUTPUT ENABLE AND DISABLE TIMES
50% V
CC
50% V
CC
90%
V
CC
VOLTAGE WAVEFORMS
RECOVERY TIME
50% V
CC
V
CC
0 V
LOAD
Input
CLK
50% V
CC
V
CC
t
rec
0 V
Figure 5. Load Circuit and Voltage Waveforms