74ACT245
OCTAL BUS TRANSCEIVER
WITH 3 STATE OUTPUTS (NON INVERTED)
s
s
s
s
s
s
s
s
s
HIGH SPEED: t
PD
= 5.4ns (TYP.) at V
CC
= 5V
LOW POWER DISSIPATION:
I
CC
= 4
µA(MAX.)
at T
A
=25°C
COMPATIBLE WITH TTL OUTPUTS
V
IH
= 2V (MIN.), V
IL
= 0.8V (MAX.)
50Ω TRANSMISSION LINE DRIVING
CAPABILITY
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 24mA (MIN)
BALANCED PROPAGATION DELAYS:
t
PLH
≅
t
PHL
OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 4.5V to 5.5V
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 245
IMPROVED LATCH-UP IMMUNITY
DIP
SOP
TSSOP
ORDER CODES
PACKAGE
DIP
SOP
TSSOP
TUBE
74ACT245B
74ACT245M
T&R
74ACT245MTR
74ACT245TTR
DESCRIPTION
The 74ACT245 is an advanced high-speed CMOS
OCTAL
BUS
TRANSCEIVER
(3-STATE)
fabricated with sub-micron silicon gate and
double-layer metal wiring C
2
MOS tecnology.
This IC is intended for two-way asynchronous
communication between data buses and the
direction of data transmission is determined by
DIR input. The enable input G can be used to
disable the device so that the buses are effectively
isolated.
PIN CONNECTION AND IEC LOGIC SYMBOLS
The device is designed to interface directly High
Speed CMOS systems with TTL, NMOS and
CMOS output voltage levels.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
IT IS PROHIBITED TO APPLY A SIGNAL TO A
TERMINAL WHEN IT IS IN OUTPUT MODE AND
WHEN A BUS THERMINAL IS FLOATING (HIGH
IMPEDANCE STATE) IT IS REQUIRED TO FIX
THE INPUT LEVEL BY MEANS OF EXTERNAL
PULL DOWN OR PULL UP RESISTOR.
April 2001
1/9
74ACT245
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
1
2, 3, 4, 5, 6,
7, 8, 9
18, 17, 16,
15, 14, 13,
12, 11
19
10
20
SYMBOL
DIR
A1 to A8
B1 to B8
NAME AND FUNCTION
Directional Control
Data Inputs/Outputs
Data Inputs/Outputs
G
GND
V
CC
Output Enable Input
Ground (0V)
Positive Supply Voltage
TRUTH TABLE
INPUTS
G
L
L
H
X : Don’t Care
Z : High Impedance
FUNCTION
DIR
L
H
X
A BUS
OUTPUT
INPUT
Z
B BUS
INPUT
OUTPUT
Z
OUTPUT
Yn
A=B
B=A
Z
ABSOLUTE MAXIMUM RATINGS
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
Parameter
Value
-0.5 to +7
-0.5 to V
CC
+ 0.5
-0.5 to V
CC
+ 0.5
±
20
±
20
±
50
±
400
-65 to +150
300
Unit
V
V
V
mA
mA
mA
mA
°C
°C
I
CC
or I
GND
DC V
CC
or Ground Current
T
stg
Storage Temperature
T
L
Lead Temperature (10 sec)
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied.
RECOMMENDED OPERATING CONDITIONS
Symbol
V
CC
V
I
V
O
T
op
dt/dv
Supply Voltage
Input Voltage
Output Voltage
Operating Temperature
Input Rise and Fall Time V
CC
= 4.5 to 5.5V (note 1)
Parameter
Value
4.5 to 5.5
0 to V
CC
0 to V
CC
-55 to 125
8
Unit
V
V
V
°C
ns/V
1) V
IN
from 0.8V to 2.0V
2/9
74ACT245
DC SPECIFICATIONS
Test Condition
Symbol
Parameter
V
CC
(V)
4.5
5.5
4.5
5.5
4.5
5.5
4.5
5.5
V
OL
Low Level Output
Voltage
4.5
5.5
4.5
5.5
I
I
I
OZ
Input Leakage Cur-
rent
High Impedance
Output Leakege
Current
Max I
CC
/Input
Quiescent Supply
Current
Dynamic Output
Current (note 1, 2)
5.5
5.5
5.5
5.5
5.5
V
O
= 0.1 V or
V
CC
-0.1V
V
O
= 0.1 V or
V
CC
-0.1V
I
O
=-50
µA
I
O
=-50
µA
I
O
=-24 mA
I
O
=-24 mA
I
O
=50
µA
I
O
=50
µA
I
O
=24 mA
I
O
=24 mA
V
I
= V
CC
or GND
V
I
= V
IH
or V
IL
V
O
= V
CC
or GND
V
I
= V
CC
- 2.1V
V
I
= V
CC
or GND
V
OLD
= 1.65 V max
V
OHD
= 3.85 V min
0.6
4
4.4
5.4
3.86
4.86
0.001
0.001
0.1
0.1
0.36
0.36
±
0.1
±
0.5
T
A
= 25°C
Min.
2.0
2.0
Typ.
1.5
1.5
1.5
1.5
4.49
5.49
0.8
0.8
4.4
5.4
3.76
4.76
0.1
0.1
0.44
0.44
±
1
±
5
1.5
40
75
-75
Max.
Value
-40 to 85°C
Min.
2.0
2.0
0.8
0.8
4.4
5.4
3.7
4.7
0.1
0.1
0.5
0.5
±
1
±
10
1.6
80
50
-50
µA
µA
mA
µA
mA
mA
V
Max.
-55 to 125°C
Min.
2.0
2.0
0.8
0.8
V
Max.
V
Unit
V
IH
V
IL
V
OH
High Level Input
Voltage
Low Level Input
Voltage
High Level Output
Voltage
I
CCT
I
CC
I
OLD
I
OHD
1) Maximum test duration 2ms, one output loaded at time
2) Incident wave switching is guaranteed on transmission lines with impedances as low as 50Ω
AC ELECTRICAL CHARACTERISTICS
(C
L
= 50 pF, R
L
= 500
Ω,
Input t
r
= t
f
= 3ns)
Test Condition
Symbol
Parameter
V
CC
(V)
5.0
(*)
5.0
(*)
5.0
(*)
T
A
= 25°C
Min.
1.5
1.5
1.5
Typ.
5.4
6.3
7.4
Max.
8.0
10.0
10.0
Value
-40 to 85°C
Min.
1.5
1.5
1.5
Max.
9.0
12.0
11.0
-55 to 125°C
Min.
1.5
1.5
1.5
Max.
10.0
13.0
12.0
ns
ns
ns
Unit
t
PLH
t
PHL
Propagation Delay
Time
t
PZL
t
PZH
Output Enable
Time
t
PLZ
t
PHZ
Output Disable
Time
(*) Voltage range is 5.0V
±
0.5V
3/9
74ACT245
CAPACITIVE CHARACTERISTICS
Test Condition
Symbol
Parameter
V
CC
(V)
5.0
5.0
5.0
f
IN
= 10MHz
T
A
= 25°C
Min.
Typ.
5
10
23
Max.
Value
-40 to 85°C
Min.
Max.
-55 to 125°C
Min.
Max.
pF
pF
pF
Unit
C
IN
C
I/O
C
PD
Input Capacitance
I/O Capacitance
Power Dissipation
Capacitance (note
1)
1) C
PD
is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
CC(opr)
= C
PD
x V
CC
x f
IN
+ I
CC
/16 (per
circuit)
TEST CIRCUIT
TEST
t
PLH
, t
PHL
t
PZL
, t
PLZ
t
PZH
, t
PHZ
C
L
= 50pF or equivalent (includes jig and probe capacitance)
R
L
= R
1
= 500Ω or equivalent
R
T
= Z
OUT
of pulse generator (typically 50Ω)
SWITCH
Open
2V
CC
Open
4/9
PCB设计
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