MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
Octal Bus Transceiver
The MC74VHCT245A is an advanced high speed CMOS octal bus
transceiver fabricated with silicon gate CMOS technology. It achieves high
speed operation similar to equivalent Bipolar Schottky TTL while maintaining
CMOS low power dissipation.
It is intended for two–way asynchronous communication between data
buses. The direction of data transmission is determined by the level of the
DIR input. The output enable pin (OE) can be used to disable the device, so
that the buses are effectively isolated.
All inputs are equipped with protection circuits against static discharge.
The VHCT inputs are compatible with TTL levels. This device can be used
as a level converter for interfacing 3.3V to 5.0V, because it has full 5V CMOS
level output swings.
The VHCT245A input and output (when disabled) structures provide
protection when voltages between 0V and 5.5V are applied, regardless of
the supply voltage. These input and output structures help prevent device
destruction caused by supply voltage – input/output voltage mismatch,
battery backup, hot insertion, etc.
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High Speed: tPD = 4.9ns (Typ) at VCC = 5V
Low Power Dissipation: ICC = 4µA (Max) at TA = 25°C
TTL–Compatible Inputs: VIL = 0.8V; VIH = 2.0V
Power Down Protection Provided on Inputs and Outputs
Balanced Propagation Delays
Designed for 4.5V to 5.5V Operating Range
Low Noise: VOLP = 1.6V (Max)
Pin and Function Compatible with Other Standard Logic Families
Latchup Performance Exceeds 300mA
ESD Performance: HBM > 2000V; Machine Model > 200V
Chip Complexity: 304 FETs or 76 Equivalent Gates
MC74VHCT245A
DW SUFFIX
20–LEAD SOIC PACKAGE
CASE 751D–04
DT SUFFIX
20–LEAD TSSOP PACKAGE
CASE 948E–02
M SUFFIX
20–LEAD SOIC EIAJ PACKAGE
CASE 967–01
ORDERING INFORMATION
MC74VHCTXXXADW
SOIC
MC74VHCTXXXADT
TSSOP
MC74VHCTXXXAM
SOIC EIAJ
APPLICATION NOTES
1. Do not force a signal on an I/O pin when it is an active output, damage may
occur.
2. All floating (high impedence) input or I/O pins must be fixed by means of
pull up or pull down resistors or bus terminator ICs.
LOGIC DIAGRAM
A1
A2
A3
A
DATA
PORT
A4
A5
A6
A7
A8
DIR
OE
2
3
4
5
6
7
8
9
1
19
18
17
16
15
14
13
12
11
B1
B2
B3
B4
B5
B6
B7
B8
B
DATA
PORT
PIN ASSIGNMENT
DIR
A1
A2
A3
A4
A5
A6
A7
A8
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCC
OE
B1
B2
B3
B4
B5
B6
B7
B8
FUNCTION TABLE
Control Inputs
OE
L
L
H
DIR
L
H
X
Operation
Data Tx from Bus B to Bus A
Data Tx from Bus A to Bus B
Buses Isolated (High–Z State)
6/97
©
Motorola, Inc. 1997
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