74AC245 [STMICROELECTRONICS]
OCTAL BUS TRANSCEIVER WITH 3 STATE OUTPUTS (NON INVERTED); 具有三态输出八路总线收发器（非反相）
| 型号： | 74AC245 |
| 厂家： | 
ST |
| 描述： | OCTAL BUS TRANSCEIVER WITH 3 STATE OUTPUTS (NON INVERTED) |
| 文件： | 总9页 (文件大小：266K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
74AC245
OCTAL BUS TRANSCEIVER
WITH 3 STATE OUTPUTS (NON INVERTED)
■
■
HIGH SPEED: t = 4.5ns (TYP.) at V = 5V
PD CC
LOW POWER DISSIPATION:
I
= 4µA(MAX.) at T =25°C
CC
A
■
■
■
■
■
■
■
HIGH NOISE IMMUNITY:
= V = 28 % V (MIN.)
50Ω TRANSMISSION LINE DRIVING
V
NIH
NIL
CC
DIP
SOP
TSSOP
T & R
CAPABILITY
SYMMETRICAL OUTPUT IMPEDANCE:
|I | = I = 24mA (MIN)
OH
OL
BALANCED PROPAGATION DELAYS:
ORDER CODES
PACKAGE
t
t
PLH
PHL
TUBE
OPERATING VOLTAGE RANGE:
(OPR) = 2V to 6V
DIP
SOP
74AC245B
74AC245M
V
CC
74AC245MTR
74AC245TTR
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 244
IMPROVED LATCH-UP IMMUNITY
TSSOP
DIR input. The enable input G can be used to
disable the device so that the buses are effectively
isolated..
All floating bus terminals during HIGH-Z state
must be held HIGH or LOW
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
DESCRIPTION
The 74AC245 is an advanced high-speed CMOS
OCTAL
BUS
TRANSCEIVER
(3-STATE)
fabricated with sub-micron silicon gate and
double-layer metal wiring C MOS tecnology.
This IC is intended for two-way asynchronous
communication between data buses and the
direction of data transmission is determined by
2
PIN CONNECTION AND IEC LOGIC SYMBOLS
April 2001
1/9
74AC245
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
SYMBOL
NAME AND FUNCTION
1
DIR
Directional Control
Data Inputs/Outputs
2, 3, 4, 5, 6,
7, 8, 9
A1 to A8
18, 17, 16,
15, 14, 13,
12, 11
B1 to B8
Data Inputs/Outputs
19
10
20
G
Output Enable Input
Ground (0V)
GND
V
Positive Supply Voltage
CC
TRUTH TABLE
INPUTS
FUNCTION
OUTPUT
Yn
G
DIR
A BUS
B BUS
L
L
L
H
X
OUTPUT
INPUT
Z
INPUT
OUTPUT
Z
A = B
B = A
Z
H
X : Don’t Care
Z : High Impedance
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
V
Supply Voltage
-0.5 to +7
V
V
CC
V
DC Input Voltage
-0.5 to V + 0.5
I
O
CC
V
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
-0.5 to V + 0.5
V
CC
I
± 20
± 20
mA
mA
mA
mA
°C
°C
IK
I
OK
I
± 50
O
I
or I
T
DC V
or Ground Current
CC
± 400
CC
GND
Storage Temperature
-65 to +150
300
stg
T
Lead Temperature (10 sec)
L
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
Parameter
Value
Unit
V
Supply Voltage
2 to 6
0 to V
V
V
CC
V
Input Voltage
I
CC
V
Output Voltage
0 to V
CC
V
O
T
Operating Temperature
-55 to 125
8
°C
ns/V
op
Input Rise and Fall Time V = 3.0, 4.5 or 5.5V (note 1)
dt/dv
CC
1) V from 30% to 70% of V
IN
CC
2/9
74AC245
DC SPECIFICATIONS
Test Condition
Value
-40 to 85°C -55 to 125°C Unit
T
= 25°C
Symbol
Parameter
A
V
CC
(V)
Min. Typ. Max. Min. Max. Min. Max.
V
High Level Input
Voltage
3.0
4.5
5.5
3.0
4.5
5.5
3.0
2.1
1.5
2.1
2.1
IH
V
V
= 0.1 V or
O
V
3.15 2.25
3.85 2.75
1.5
3.15
3.85
3.15
3.85
V
V
-0.1V
CC
V
Low Level Input
Voltage
0.9
0.9
0.9
IL
= 0.1 V or
O
V
2.25 1.35
2.75 1.65
2.99
1.35
1.65
1.35
1.65
-0.1V
CC
V
High Level Output
Voltage
I =-50 µA
2.9
4.4
2.9
4.4
2.9
4.4
5.4
2.4
3.7
4.7
OH
O
I =-50 µA
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
4.49
5.49
O
I =-50 µA
5.4
5.4
O
V
V
I =-12 mA
2.56
3.86
4.86
2.46
3.76
4.76
O
I =-24 mA
O
I =-24 mA
O
V
Low Level Output
Voltage
I =50 µA
0.002 0.1
0.001 0.1
0.001 0.1
0.36
0.1
0.1
0.1
0.1
0.1
0.5
0.5
0.5
OL
O
I =50 µA
O
I =50 µA
0.1
O
I =12 mA
0.44
0.44
0.44
O
I =24 mA
0.36
O
I =24 mA
0.36
O
I
Input Leakage
Current
I
V = V
or GND
CC
5.5
± 0.1
± 0.5
4
± 1
± 5
40
± 1
± 10
80
µA
µA
µA
I
Ioz
High Impedance
Output Leakage
Current
V = V or V
IL
I
IH
5.5
V
= V or GND
CC
O
I
Quiescent Supply
Current
CC
V = V
or GND
CC
5.5
5.5
I
I
V
= 1.65 V max
= 3.85 V min
75
50
mA
mA
OLD
OLD
Dynamic Output
Current (note 1, 2)
I
V
OHD
-75
-50
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
3/9
74AC245
AC ELECTRICAL CHARACTERISTICS (C = 50 pF, R = 500 Ω, Input t = t = 3ns)
L
L
r
f
Test Condition
Value
T
= 25°C
Symbol
Parameter
-40 to 85°C -55 to 125°C Unit
A
V
CC
(V)
Min. Typ. Max. Min. Max. Min. Max.
(*)
t
t
Propagation Delay
Time
1.5
1.5
1.5
1.5
1.5
1.5
5.5
4.5
7.5
5.5
6.2
5.2
8.5
6.5
1.5
1.5
1.5
1.5
1.5
1.5
9.0
7.0
1.5
1.5
1.5
1.5
1.5
1.5
11.5
8.5
PLH PHL
3.3
ns
ns
ns
(**)
(*)
5.0
t
t
Output Enable
Time
12.0
9.0
13.5
9.5
14.0
10.5
14.0
10.5
PZL PZH
3.3
(**)
5.0
3.3
(*)
(**)
t
t
Output Disable
Time
12.0
9.0
13.0
10.0
PLZ PHZ
5.0
(*) Voltage range is 3.3V ± 0.3V
(**) Voltage range is 5.0V ± 0.5V
CAPACITIVE CHARACTERISTICS
Test Condition
Value
T
= 25°C
Symbol
Parameter
-40 to 85°C -55 to 125°C Unit
A
V
CC
(V)
Min. Typ. Max. Min. Max. Min. Max.
C
Input Capacitance
I/O Capacitance
5.0
5.0
5
pF
pF
IN
C
10
I/O
C
Power Dissipation
Capacitance (note
1)
PD
f
= 10MHz
5.0
21
pF
IN
1) C is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without
PD
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
circuit)
= C x V x f + I /16 (per
PD CC IN CC
CC(opr)
TEST CIRCUIT
TEST
SWITCH
t
t
t
, t
Open
PLH PHL
, t
2V
CC
PZL PLZ
, t
Open
PZH PHZ
C
R
R
= 50pF or equivalent (includes jig and probe capacitance)
L
L
T
= R = 500Ω or equivalent
1
= Z
of pulse generator (typically 50Ω)
OUT
4/9
74AC245
WAVEFORM 1: PROPAGATION DELAYS (f=1MHz; 50% duty cycle)
WAVEFORM 2: OUTPUT ENABLE AND DISABLE TIME (f=1MHz; 50% duty cycle)
5/9
74AC245
Plastic DIP-20 (0.25) MECHANICAL DATA
mm
inch
TYP.
DIM.
MIN.
0.254
1.39
TYP.
MAX.
MIN.
0.010
0.055
MAX.
a1
B
b
1.65
0.065
0.45
0.25
0.018
0.010
b1
D
E
e
25.4
1.000
8.5
2.54
0.335
0.100
0.900
e3
F
22.86
7.1
0.280
0.155
I
3.93
L
3.3
0.130
Z
1.34
0.053
P001J
6/9
74AC245
SO-20 MECHANICAL DATA
mm
inch
TYP.
DIM.
MIN.
TYP.
MAX.
2.65
0.20
2.45
0.49
0.32
MIN.
MAX.
0.104
0.007
0.096
0.019
0.012
A
a1
a2
b
0.10
0.004
0.35
0.23
0.013
0.009
b1
C
0.50
0.020
c1
D
45 (typ.)
12.60
10.00
13.00
10.65
0.496
0.393
0.512
0.419
E
e
1.27
0.050
0.450
e3
F
11.43
7.40
0.50
7.60
1.27
0.75
0.291
0.19
0.299
0.050
0.029
L
M
S
8 (max.)
P013L
7/9
74AC245
TSSOP20 MECHANICAL DATA
mm
inch
TYP.
DIM.
MIN.
TYP.
MAX.
1.1
MIN.
MAX.
0.433
0.006
0.374
0.0118
0.0079
0.260
0.256
0.176
A
A1
A2
b
0.05
0.85
0.19
0.09
6.4
0.10
0.9
0.15
0.95
0.30
0.2
0.002
0.335
0.0075
0.0035
0.252
0.246
0.169
0.004
0.354
c
D
6.5
6.4
6.6
0.256
0.252
E
6.25
4.3
6.5
E1
e
4.4
4.48
0.173
0.65 BSC
4o
0.0256 BSC
4o
K
0o
8o
0o
8o
L
0.50
0.60
0.70
0.020
0.024
0.028
A2
A
K
L
b
e
A1
E
c
D
E1
PIN 1 IDENTIFICATION
1
8/9
74AC245
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of STMicroelectronics.
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© 2001 STMicroelectronics - Printed in Italy - All Rights Reserved
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9/9
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