SN74HCT646 Datasheet, PDF (7/11 Pages) Texas Instruments – OCTAL BUS TRANSCEIVERS AND REGISTERS WITH 3-STATE OUTPUTS

SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178C – MARCH 1984 – REVISED MARCH 2003
PARAMETER MEASUREMENT INFORMATION
Test
From Output ^{Point RL}
Under Test
CL
(see Note A)
VCC
S1
S2
LOAD CIRCUIT
PARAMETER RL
tPZH
ten
1 kΩ
tPZL
tdis
tPHZ _{1 kΩ}
tPLZ
tpd or tt
––
CL
50 pF
or
150 pF
S1
Open
Closed
Open
50 pF
Closed
50 pF
or
150 pF
Open
S2
Closed
Open
Closed
Open
Open
High-Level
Pulse
Low-Level
Pulse
1.3 V
tw
1.3 V
3V
1.3 V
0V
3V
1.3 V
0V
VOLTAGE WAVEFORMS
PULSE DURATIONS
Reference
Input
Data
Input
1.3 V
0.3 V
1.3 V
tsu
2.7 V
th
2.7 V
tr
3V
0V
3V
1.3 V
0.3 V _{0 V}
tf
VOLTAGE WAVEFORMS
SETUP AND HOLD AND INPUT RISE AND FALL TIMES
Input
In-Phase
Output
Out-of-
Phase
Output
1.3 V
tPLH
1.3 V
10%
tPHL
90%
90%
tr
1.3 V
10%
tf
1.3 V
tPHL
90%
tPLH
1.3 V
10%
3V
0V
VOH
1.3 V
10% _VOL
tf
90% ^VOH
VOL
tr
VOLTAGE WAVEFORMS
PROPAGATION DELAY AND OUTPUT RISE AND FALL TIMES
Output
Control
(Low-Level
Enabling)
tPZL
Output
Waveform 1
(See Note B)
tPZH
Output
Waveform 2
(See Note B)
1.3 V
1.3 V
1.3 V
1.3 V
3V
tPLZ
0V
≈VCC
10% _VOL
tPHZ
90% ^VOH
≈0 V
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES FOR 3-STATE OUTPUTS
NOTES: A. CL 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, ZO = 50 Ω, tr = 6 ns, tf = 6 ns.
D. For clock inputs, fmax is measured when the input duty cycle is 50%.
E. The outputs are measured one at a time with one input transition per measurement.
F. tPLZ and tPHZ are the same as tdis.
G. tPZL and tPZH are the same as ten.
H. tPLH and tPHL are the same as tpd.
Figure 2. Load Circuit and Voltage Waveforms
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