HD74AC245/HD74ACT245
Octal Bidirectional Transceiver with 3-State Input/Output
Description
The HD74AC245/HD74ACT245 contains eight non-inverting bidirectional buffers with 3-state outputs and
is intended for bus-oriented applications. Current sinking capability is 24 mA at both the A and B ports.
The Transmit/Receive (T/R) input determines the direction of data flow through the bidirectional
transceiver. Transmit (active-High) enables data from A ports to B ports; Receive (active-Low) enables
data from B ports to A ports. The Output Enable input, when High, disables, both A and B ports by placing
them in a High Z condition.
Features
•
Noninverting Buffers
•
Bidirectional Data Path
•
A and B Outputs Source/Sink 24 mA
•
HD74ACT245 has TTL-Compatible Inputs
Pin Names
OE
T/R
A
0
to A
7
B
0
to B
7
Output Enable Input
Transmit/Receive Input
Side A 3-State Inputs or 3-State Outputs
Side B 3-State Inputs or 3-State Outputs
HD74AC245/HD74ACT245
DC Characteristics
(unless otherwise specified)
Item
Maximum quiescent supply current
Maximum quiescent supply current
Maximum additional I
CC
/input
(HD74ACT245)
Symbol
I
CC
I
CC
I
CCT
Max
80
8.0
1.5
Unit
µA
µA
mA
Condition
V
IN
= V
CC
or ground, V
CC
= 5.5 V,
Ta = Worst case
V
IN
= V
CC
or ground, V
CC
= 5.5 V,
Ta = 25°C
V
IN
= V
CC
– 2.1 V, V
CC
= 5.5 V,
Ta = Worst case
AC Characteristics: HD74AC245
Ta = +25°C
C
L
= 50 pF
Item
Propagation delay
Data to output
Propagation delay
Data to output
Output enable time
t
PZH
t
PHL
Symbol
t
PLH
V
CC
(V)*
1
3.3
5.0
3.3
5.0
3.3
5.0
Output enable time
t
PZL
3.3
5.0
Output disable time
t
PHZ
3.3
5.0
Output disable time
t
PLZ
3.3
5.0
Note:
1. Voltage Range 3.3 is 3.3 V
±
0.3 V
Voltage Range 5.0 is 5.0 V
±
0.5 V
Min
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Typ
5.0
3.5
5.0
3.5
7.0
5.0
7.5
5.5
6.5
5.5
7.0
5.5
Max
8.5
6.5
8.5
6.0
11.5
8.5
12.0
9.0
12.0
9.0
11.5
9.0
Ta = –40°C to +85°C
C
L
= 50 pF
Min
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Max
9.0
7.0
9.0
7.0
12.5
9.0
13.5
9.5
12.5
10.0
13.0
10.0
ns
ns
ns
ns
ns
Unit
ns
3
HD74AC245/HD74ACT245
AC Characteristics: HD74ACT245
Ta = +25°C
C
L
= 50 pF
Item
Propagation delay
Data to output
Propagation delay
Data to output
Output enable time
Output enable time
Output disable time
Output disable time
Note:
Symbol
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
V
CC
(V)*
1
5.0
5.0
5.0
5.0
5.0
5.0
Min
1.0
1.0
1.0
1.0
1.0
1.0
Typ
4.0
4.0
5.0
5.5
5.5
5.0
Max
7.5
8.0
10.0
10.0
10.0
10.0
Ta = –40°C to +85°C
C
L
= 50 pF
Min
1.0
1.0
1.0
1.0
1.0
1.0
Max
8.0
9.0
11.0
12.0
11.0
11.0
Unit
ns
ns
ns
ns
ns
ns
1. Voltage Range 5.0 is 5.0 V
±
0.5 V
Capacitance
Item
Input capacitance
Input/output capacitance
Power dissipation capacitance
Symbol
C
IN
C
I/O
C
PD
Typ
4.5
15.0
45.0
Unit
pF
pF
pF
Condition
V
CC
= 5.5 V
V
CC
= 5.5 V
V
CC
= 5.0 V
4
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