HIT HD74ACT245, HD74AC245 Datasheet
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 Output Enable Input
T/R Transmit/Receive Input
A0 to A7Side A 3-State Inputs or 3-State Outputs
B0 to B7Side B 3-State Inputs or 3-State Outputs
HD74AC245/HD74ACT245
Pin Arrangement
Truth Tables
1
2
A
0
A1
3
A2
4
A3
5
A4
6
A5
7
A6
8
A7
9
GND
10 11
(Top view)
20T/R VCC
OE
19
18
B0
B1
17
B2
16
B3
15
B4
14
B5
13
12
B6
B7
Inputs
OE T/R Outputs
L L Bus B Data to Bus A
L H Bus A Data to Bus B
H X High Z State
H : High Voltage Level
L : Low Voltage Level
X : Immaterial
2
HD74AC245/HD74ACT245
DC Characteristics (unless otherwise specified)
Item Symbol Max Unit Condition
Maximum quiescent supply current I
Maximum quiescent supply current I
Maximum additional ICC/input
CC
CC
I
CCT
(HD74ACT245)
AC Characteristics: HD74AC245
80 µAV
8.0 µAV
1.5 mA VIN = VCC – 2.1 V, VCC = 5.5 V,
= VCC or ground, VCC = 5.5 V,
IN
Ta = Worst case
= VCC or ground, VCC = 5.5 V,
IN
Ta = 25°C
Ta = Worst case
Item Symbol V
Propagation delay t
PLH
Ta = +25°C
C
= 50 pF
L
(V)*1Min Typ Max Min Max Unit
CC
3.3 1.0 5.0 8.5 1.0 9.0 ns
Ta = –40°C to +85°C
CL = 50 pF
Data to output 5.0 1.0 3.5 6.5 1.0 7.0
Propagation delay t
PHL
3.3 1.0 5.0 8.5 1.0 9.0 ns
Data to output 5.0 1.0 3.5 6.0 1.0 7.0
Output enable time t
PZH
3.3 1.0 7.0 11.5 1.0 12.5 ns
5.0 1.0 5.0 8.5 1.0 9.0
Output enable time t
PZL
3.3 1.0 7.5 12.0 1.0 13.5 ns
5.0 1.0 5.5 9.0 1.0 9.5
Output disable time t
PHZ
3.3 1.0 6.5 12.0 1.0 12.5 ns
5.0 1.0 5.5 9.0 1.0 10.0
Output disable time t
PLZ
3.3 1.0 7.0 11.5 1.0 13.0 ns
5.0 1.0 5.5 9.0 1.0 10.0
Note: 1. Voltage Range 3.3 is 3.3 V ± 0.3 V
Voltage Range 5.0 is 5.0 V ± 0.5 V
3
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