74AC245
OCTAL BUS TRANSCEIVER
WITH 3 STATE OUTPUTS (NON INVERTED)
■
■
■
■
■
■
■
■
■
HIGH SPEED: tPD = 4.5ns (TYP.) at VCC = 5V
LOW POWER DISSIPATION:
ICC = 4µA(MAX.) at TA=25°C
HIGH NOISE IMMUNITY:
VNIH = V NIL = 28 % VCC (MIN.)
50Ω TRANSMISSION LINE DRIVING
CAPABILITY
SYMMETRICAL OUTPUT IMPEDANCE:
|IOH| = IOL = 24mA (MIN)
BALANCED PROPAGATION DELAYS:
tPLH ≅ tPHL
OPERATING VOLTAGE RANGE:
VCC (OPR) = 2V to 6V
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 244
IMPROVED LATCH-UP IMMUNITY
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 C2MOS tecnology.
This IC is intended for two-way asynchronous
communication between data buses and the
direction of data transmission is determined by
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DIP
SOP
TSSOP
ORDER CODES
PACKAGE
TUBE
DIP
SOP
TSSOP
74AC245B
74AC245M
)
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T&R
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74AC245MTR
74AC245TTR
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.
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PIN CONNECTION AND IEC LOGIC SYMBOLS
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April 2001
1/9
74AC245
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
SYMBOL
NAME AND FUNCTION
1
2, 3, 4, 5, 6,
7, 8, 9
18, 17, 16,
15, 14, 13,
12, 11
19
10
20
DIR
A1 to A8
Directional Control
Data Inputs/Outputs
B1 to B8
Data Inputs/Outputs
G
GND
VCC
Output Enable Input
Ground (0V)
Positive Supply Voltage
TRUTH TABLE
INPUTS
FUNCTION
G
DIR
A BUS
B BUS
L
L
H
L
H
X
OUTPUT
INPUT
Z
INPUT
OUTPUT
Z
X : Don’t Care
Z : High Impedance
Symbol
so
Parameter
Supply Voltage
VI
DC Input Voltage
VO
DC Output Voltage
IIK
DC Input Diode Current
IOK
DC Output Diode Current
IO
DC Output Current
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(t s)
b
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-
ICC or IGND DC VCC or Ground Current
Tstg
Storage Temperature
TL
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Lead Temperature (10 sec)
)
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let
ABSOLUTE MAXIMUM RATINGS
VCC
OUTPUT
A=B
B=A
Z
Value
Unit
-0.5 to +7
V
-0.5 to VCC + 0.5
V
-0.5 to VCC + 0.5
± 20
V
mA
± 20
mA
± 50
mA
± 400
mA
-65 to +150
°C
300
°C
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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
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Symbol
VCC
Parameter
Supply Voltage
VI
Input Voltage
VO
Output Voltage
Top
Operating Temperature
dt/dv
Input Rise and Fall Time VCC = 3.0, 4.5 or 5.5V (note 1)
1) VIN from 30% to 70% of V CC
2/9
Value
Unit
2 to 6
V
0 to VCC
V
0 to VCC
V
-55 to 125
°C
8
ns/V
74AC245
DC SPECIFICATIONS
Test Condition
Symbol
VIH
Parameter
High Level Input
Voltage
Low Level Input
Voltage
VIL
High Level Output
Voltage
VOH
VOL
Low Level Output
Voltage
II
Input Leakage
Current
High Impedance
Output Leakage
Current
Quiescent Supply
Current
Ioz
ICC
IOLD
IOHD
Dynamic Output
Current (note 1, 2)
Value
TA = 25°C
VCC
(V)
3.0
4.5
5.5
3.0
4.5
5.5
VO = 0.1 V or
VCC-0.1V
Min.
Typ.
2.1
3.15
3.85
1.5
2.25
2.75
1.5
2.25
2.75
VO = 0.1 V or
VCC-0.1V
Max.
-40 to 85°C
-55 to 125°C
Min.
Min.
Max.
2.1
3.15
3.85
0.9
1.35
1.65
Max.
2.1
3.15
3.85
0.9
1.35
1.65
V
0.9
1.35
1.65
3.0
IO=-50 µA
2.9
2.99
2.9
2.9
4.5
IO=-50 µA
4.4
4.49
4.4
4.4
5.5
IO=-50 µA
5.4
5.49
5.4
5.4
3.0
IO=-12 mA
2.56
2.46
2.4
4.5
IO=-24 mA
3.86
3.76
3.7
5.5
IO=-24 mA
4.86
4.76
4.7
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3.0
IO=50 µA
0.002
0.1
0.1
IO=50 µA
0.001
0.1
5.5
IO=50 µA
0.001
3.0
IO=12 mA
0.36
od
0.44
0.5
4.5
IO=24 mA
5.5
IO=24 mA
5.5
VI = VCC or GND
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5.5
VI = VIH or VIL
VO = VCC or GND
5.5
VI = VCC or GND
0.1
0.1
0.1
V
0.44
0.5
0.44
0.5
± 0.1
±1
±1
µA
± 0.5
±5
± 10
µA
4
40
80
µA
VOLD = 1.65 V max
75
50
mA
VOHD = 3.85 V min
-75
-50
mA
c
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5.5
Pr
0.1
0.36
(t s)
0.36
0.1
V
V
4.5
0.1
Unit
b
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-
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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
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3/9
74AC245
AC ELECTRICAL CHARACTERISTICS (CL = 50 pF, RL = 500 Ω, Input tr = tf = 3ns)
Test Condition
Symbol
Parameter
Value
TA = 25°C
VCC
(V)
tPLH tPHL Propagation Delay
Time
tPZL tPZH Output Enable
Time
tPLZ tPHZ Output Disable
Time
-40 to 85°C
-55 to 125°C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
(*)
1.5
5.5
8.5
1.5
9.0
1.5
11.5
(**)
5.0
1.5
4.5
6.5
1.5
7.0
1.5
8.5
3.3(*)
1.5
7.5
12.0
1.5
13.5
1.5
14.0
5.0(**)
1.5
5.5
9.0
1.5
9.5
1.5
10.5
3.3(*)
1.5
6.2
12.0
1.5
13.0
1.5
14.0
(**)
1.5
5.2
9.0
1.5
10.0
1.5
10.5
3.3
5.0
Unit
ns
ns
ns
(*) Voltage range is 3.3V ± 0.3V
(**) Voltage range is 5.0V ± 0.5V
CAPACITIVE CHARACTERISTICS
Test Condition
Symbol
Parameter
Value
TA = 25°C
VCC
(V)
Min.
Typ.
CIN
Input Capacitance
5.0
5
CI/O
I/O Capacitance
5.0
10
CPD
Power Dissipation
Capacitance (note
1)
5.0
fIN = 10MHz
Max.
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21
-40 to 85°C
Min.
-55 to 125°C
od
Max.
Pr
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Min.
Unit
Max.
pF
pF
pF
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1) CPD 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. ICC(opr) = CPD x VCC x fIN + ICC/16 (per
circuit)
TEST CIRCUIT
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TEST
SWITCH
tPLH, tPHL
Open
tPZL, tPLZ
2VCC
tPZH, tPHZ
Open
CL = 50pF or equivalent (includes jig and probe capacitance)
RL = R1 = 500Ω or equivalent
RT = ZOUT of pulse generator (typically 50Ω)
4/9
74AC245
WAVEFORM 1: PROPAGATION DELAYS (f=1MHz; 50% duty cycle)
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WAVEFORM 2: OUTPUT ENABLE AND DISABLE TIME (f=1MHz; 50% duty cycle)
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5/9
74AC245
Plastic DIP-20 (0.25) MECHANICAL DATA
mm
DIM.
MIN.
a1
0.254
B
1.39
TYP.
inch
MAX.
MIN.
TYP.
MAX.
0.010
1.65
0.055
0.065
b
0.45
0.018
b1
0.25
0.010
D
25.4
1.000
E
8.5
0.335
e
2.54
0.100
e3
22.86
0.900
F
7.1
I
3.93
L
c
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3.3
Z
1.34
)
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s
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0.280
0.155
0.130
0.053
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P001J
6/9
74AC245
SO-20 MECHANICAL DATA
mm
DIM.
MIN.
TYP.
A
inch
MAX.
MIN.
TYP.
a1
2.65
0.10
0.104
0.20
a2
MAX.
0.004
0.007
2.45
0.096
b
0.35
0.49
0.013
0.019
b1
0.23
0.32
0.009
0.012
C
0.50
0.020
c1
45 (typ.)
D
12.60
13.00
0.496
E
10.00
10.65
0.393
0.419
c
u
d
e
1.27
0.050
e3
11.43
0.450
F
7.40
7.60
0.291
L
0.50
1.27
0.19
M
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0.75
S
8 (max.)
)
s
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0.512
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0.299
0.050
0.029
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P013L
7/9
74AC245
TSSOP20 MECHANICAL DATA
mm
DIM.
MIN.
inch
TYP.
MAX.
A
TYP.
MAX.
1.1
0.433
A1
0.05
0.10
0.15
0.002
0.004
0.006
A2
0.85
0.9
0.95
0.335
0.354
0.374
b
0.19
0.30
0.0075
0.0118
c
0.09
0.2
0.0035
0.0079
D
6.4
6.5
6.6
0.252
0.256
E
6.25
6.4
6.5
0.246
0.252
E1
4.3
4.4
4.48
0.169
0.173
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0.65 BSC
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K
0
L
0.50
A
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4
8
0.60
0.70
)
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du
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b
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-
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1
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0.256
0.176
4o
8o
0.020
0.024
0.028
K
L
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c
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PIN 1 IDENTIFICATION
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0.260
0.0256 BSC
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A2
A1
8/9
MIN.
74AC245
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)
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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.
© The ST logo is a registered trademark of STMicroelectronics
© 2001 STMicroelectronics - Printed in Italy - All Rights Reserved
STMicroelectronics GROUP OF COMPANIES
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9/9
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