5-398
FAST AND LS TTL DATA
OCTAL BUS TRANSCEIVER
The SN54 /74LS245 is an Octal Bus Transmitter/Receiver designed for
8-line asynchronous 2-way data communication between data buses.
Direction Input (DR) controls transmission of Data from bus A to bus B or bus
B to bus A depending upon its logic level. The Enable input (E) can be used
to isolate the buses.
•Hysteresis Inputs to Improve Noise Immunity
•2-Way Asynchronous Data Bus Communication
•Input Diodes Limit High-Speed Termination Effects
•ESD > 3500 Volts
LOGIC AND CONNECTION DIAGRAMS DIP (TOP VIEW)
18 17 16 15 14 13
1 2 3 4 5 6 7
20 19
8
VCC
DIR
EB1 B2 B3 B5B4 B6
A1 A2 A3 A4 A5 A6 A7
9 10
A8 GND
12 11
B7 B8
TRUTH TABLE
INPUTS
OUTPUT
E DIR
OUTPUT
L L Bus B Data to Bus A
L H Bus A Data to Bus B
H X Isolation
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
GUARANTEED OPERATING RANGES
Symbol Parameter Min Typ Max Unit
VCC Supply Voltage 54
74 4.5
4.75 5.0
5.0 5.5
5.25 V
TAOperating Ambient Temperature Range 54
74 –55
025
25 125
70 °C
IOH Output Current — High
54, 74 –3.0 mA
OH
54
74 –12
–15 mA
IOL Output Current — Low 54
74 12
24 mA
SN54/74LS245
OCTAL BUS TRANSCEIVER
LOW POWER SCHOTTKY
ORDERING INFORMATION
SN54LSXXXJ Ceramic
SN74LSXXXN Plastic
SN74LSXXXDW SOIC
20
1
J SUFFIX
CERAMIC
CASE 732-03
20 1
N SUFFIX
PLASTIC
CASE 738-03
20
1
DW SUFFIX
SOIC
CASE 751D-03
5-399
FAST AND LS TTL DATA
SN54/74LS245
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min Typ Max
Unit
Test Conditions
VIH Input HIGH Voltage 2.0 V Guaranteed Input HIGH Voltage for
All Inputs
VIL
Input LOW Voltage
54 0.7
V
Guaranteed Input LOW Voltage for
All Inputs
VIL
Input LOW Voltage
74 0.8
V
Guaranteed Input LOW Voltage for
All Inputs
VT+–VT– Hysteresis 0.2 0.4 V VCC = MIN
VIK Input Clamp Diode Voltage –0.65 –1.5 V VCC = MIN, IIN = –18 mA
VOH
Output HIGH Voltage
54, 74 2.4 3.4 V VCC = MIN, IOH = –3.0 mA
VOH
Output HIGH Voltage
54, 74 2.0 V VCC = MIN, IOH = MAX
VOL
Output LOW Voltage
54, 74 0.25 0.4 V IOL = 12 mA
VCC = VCC MIN,
VIN = VIL or VIH
per Truth Table
VOL
Output LOW Voltage
74 0.35 0.5 V IOL = 24 mA
VIN = VIL or VIH
per Truth Table
IOZH Output Off Current HIGH 20 µA VCC = MAX, VOUT = 2.7 V
IOZL Output Off Current LOW –200 µA VCC = MAX, VOUT = 0.4 V
IIH
Input HIGH Current
A or B, DR or E 20 µA VCC = MAX, VIN = 2.7 V
IIH Input HIGH Current
DR or E 0.1 mA VCC = MAX, VIN = 7.0 V
IH
A or B 0.1 mA VCC = MAX, VIN = 5.5 V
IIL Input LOW Current –0.2 mA VCC = MAX, VIN = 0.4 V
IOS Output Short Circuit Current (Note 1) –40 –225 mA VCC = MAX
ICC
Power Supply Current
Total, Output HIGH 70
mA
VCC = MAX
ICC
Total, Output LOW 90
mA
VCC = MAX
Total at HIGH Z 95
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (TA = 25°C, VCC = 5.0 V, TRISE/TFALL ≤ 6.0 ns)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min Typ Max
Unit
Test Conditions
tPLH
tPHL Propagation Delay, Data to Output 8.0
8.0 12
12 ns
CL = 45 pF,
RL = 667 Ω
tPZH Output Enable Time to HIGH Level 25 40 ns
CL = 45 pF,
RL = 667 Ω
tPZL Output Enable Time to LOW Level 27 40 ns
tPLZ Output Disable Time from LOW Level 15 25 ns
C
L = 5.0 pF,
RL = 667 Ω
tPHZ Output Disable Time from HIGH Level 15 25 ns
CL = 5.0 pF,
RL = 667 Ω
5-400
FAST AND LS TTL DATA
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MFJ
Case 751D-03 DW Suffix
20-Pin Plastic
SO-20 (WIDE)
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20-Pin Ceramic Dual In-Line
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Case 738-03 N Suffix
20-Pin Plastic
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1 10
1120
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5-401
FAST AND LS TTL DATA
SYMBOL SW1 SW2
tPZH Open Closed
tPZL Closed Open
tPLZ Closed Closed
tPHZ Closed Closed
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