74VHC245 Octal Bidirectional Transceiver with 3-STATE Outputs
November 1992
Revised April 2005
74VHC245
Octal Bidirectional Transceiver with 3-STATE Outputs
General Description
The VHC245 is an advanced high speed CMOS octal bus
transceiver fabricated with silicon gate CMOS technology.
It achieves high speed operation similar to equivalent Bipo-
lar Schottky TTL while maintaining the CMOS low power
dissipation. The VHC245 is intended for bidirectional asyn-
chronous communication between data busses. The direc-
tion of data transmission is determined by the level of the
T/R input. The enable input can be used to disable the
device so that the busses are effectively isolated. All inputs
are equipped with protection circuits against static dis-
charge.
Features
s
High Speed: t
PD
4.0 ns (typ) at V
CC
V
NIL
5V
s
High Noise Immunity: V
NIH
s
Low Noise: V
OLP
28% V
CC
(Min)
s
Power Down Protection is provided on all inputs
0.9V (typ)
25
q
C
s
Low Power Dissipation:
I
CC
4
P
A (Max) @ T
A
s
Pin and Function Compatible with 74HC245
Ordering Code:
Order Number
74VHC245M
74VHC245SJ
74VHC245MTC
74VHC245N
Package Number
M20B
M20D
MTC20
N20A
Package Description
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide
Pb-Free 20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Surface mount packages are also available on Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Pb-Free package per JEDEC J-STD-020B.
Logic Symbol
IEEE/IEC
Connection Diagram
Pin Description
Pin
Names
OE
T/R
A
0
–A
7
B
0
–B
7
Output Enable Input
Transmit/Receive Input
Side A Inputs or 3-STATE Outputs
Side B Inputs or 3-STATE Outputs
Description
Truth Table
Inputs
OE
L
L
H
T/R
L
H
X
Bus B Data to Bus A
Bus A Data to Bus B
HIGH-Z State
Outputs
H HIGH Voltage Level L LOW Voltage Level X Immaterial
Any unused bus terminals during HIGH-Z State must be held HIGH or
LOW.
© 2005 Fairchild Semiconductor Corporation
DS011520
www.fairchildsemi.com
74VHC245
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
CC
)
DC Input Voltage (V
IN
) (T/R, OE)
DC Output Voltage (V
OUT
)
Input Diode Current (I
IK
) (T/R, OE)
Output Diode Current (I
OK
)
DC Output Current (I
OUT
)
DC V
CC
/GND Current (I
CC
)
Storage Temperature (T
STG
)
Lead Temperature (T
L
)
(Soldering, 10 seconds)
260
q
C
0.5V to
7.0V
0.5V to 7.0V
0.5V to V
CC
0.5V
20 mA
r
20 mA
r
25 mA
r
75 mA
65
q
C to
150
q
C
Recommended Operating
Conditions
(Note 2)
Supply Voltage (V
CC
)
Input Voltage (V
IN
)(T/R, OE)
Output Voltage (V
OUT
)
Operating Temperature (T
OPR
)
Input Rise and Fall Time (t
r
, t
f
)
V
CC
V
CC
3.3V
r
0.3V
5.0V
r
0.5V
0
a
100 ns/V
0
a
20 ns/V
2.0V to 5.5V
0V to 5.5V
0V to V
CC
40
q
C to
85
q
C
Note 1:
Absolute Maximum Ratings are values beyond which the device
may be damaged or have its useful life impaired. The databook specifica-
tions should be met, without exception, to ensure that the system design is
reliable over its power supply, temperature, and output/input loading vari-
ables. Fairchild does not recommend operation outside databook specifica-
tions.
Note 2:
Unused inputs or I/O pins must be held HIGH or LOW. They may
not float.
DC Electrical Characteristics
Symbol
V
IH
V
IL
V
OH
Parameter
HIGH Level
Input Voltage
LOW Level
Input Voltage
HIGH Level
Output Voltage
V
CC
(V)
2.0
3.0
5.5
2.0
3.0
5.5
2.0
3.0
4.5
3.0
4.5
V
OL
LOW Level
Output Voltage
2.0
3.0
4.5
3.0
4.5
I
OZ
3-STATE Output
Off-State Current
I
IN
(T/R, OE)
I
CC
Input Leakage
Current
Quiescent Supply Current
5.5
4.0
40.0
5.5
0
5.5
1.9
2.9
4.4
2.58
3.94
0.0
0.0
0.0
0.1
0.1
0.1
0.36
0.36
2.0
3.0
4.5
Min
1.50
0.7 V
CC
0.50
0.3 V
CC
1.9
2.9
4.4
2.48
3.80
0.1
0.1
0.1
0.44
0.44
V
V
IN
I
OL
I
OL
V
OUT
V
IN
OE
V
IN
V
IN
4 mA
8 mA
V
V
V
IN
I
OH
I
OH
V
IH
I
OL
or V
IL
V
T
A
25
q
C
Typ
Max
T
A
40
q
C to
85
q
C
Max
Min
1.50
0.7 V
CC
Units
V
Conditions
0.50
0.3 V
CC
V
V
IN
V
IH
I
OH
or V
IL
50
P
A
4 mA
8 mA
50
P
A
V
CC
or GND
V
CC
or GND
V
IH
or V
IL
5.5V or GND
V
CC
or GND
r
0.25
r
0.1
r
2.5
r
1.0
P
A
P
A
P
A
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2
74VHC245
Noise Characteristics
Symbol
V
OLP
(Note 3)
V
OLV
(Note 3)
V
IHD
(Note 3)
V
ILD
(Note 3)
Parameter
Quiet Output Maximum
Dynamic V
OL
Quiet Output Minimum
Dynamic V
OL
Minimum HIGH Level
Dynamic Input Voltage
Maximum LOW Level
Dynamic Input Voltage
5.0
1.5
V
C
L
50 pF
5.0
3.5
V
C
L
50 pF
5.0
V
CC
(V)
5.0
T
A
Typ
0.9
25
q
C
Limits
1.2
Units
V
V
C
L
C
L
50 pF
50 pF
Conditions
0.9
1.2
Note 3:
Parameter guaranteed by design.
AC Electrical Characteristics
Symbol
t
PLH
t
PHL
Parameter
Propagation Delay
Time
5.0
r
0.5
t
PZL
t
PZH
3-STATE Output
Enable Time
5.0
r
0.5
t
PLZ
t
PHZ
t
OSLH
t
OSHL
C
IN
(T/R, OE)
C
I/O
C
PD
Output Capacitance
Power Dissipation
Capacitance
Note 4:
Parameter guaranteed by design. t
OSLH
|t
PLH max
t
PLH min
|; t
OSHL
|t
PHL max
t
PHL min
|
Note 5:
C
PD
is defined as the value of the internal equivalent capacitance which is calculated from the operating current consumption without load. Average
operating current can be obtained by the equation: I
CC
(opr.) C
PD
* V
CC
* f
IN
I
CC
/8 (per Bit).
V
CC
(V)
3.3
r
0.3
Min
T
A
25
q
C
Typ
5.8
8.3
4.0
5.5
8.5
11.0
5.8
7.3
11.5
7.0
Max
8.4
11.9
5.5
7.5
13.2
16.7
8.5
10.6
15.8
9.7
1.5
1.0
4
8
21
10
T
A
40
q
C to
85
q
C
Max
10.0
13.5
6.5
8.5
15.5
19.0
10.0
12.0
18.0
11.0
1.5
1.0
10
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Min
Units
ns
ns
ns
R
L
ns
ns
ns
pF
pF
pF
R
L
Conditions
C
L
C
L
C
L
C
L
C
L
1 k
:
C
L
C
L
C
L
1 k
:
C
L
C
L
C
L
C
L
15 pF
50 pF
15 pF
50 pF
15 pF
50 pF
15 pF
50 pF
50 pF
50 pF
50 pF
50 pF
3.3
r
0.3
3-STATE Output
Disable Time
Output to Output
Skew
Input Capacitance
3.3
r
0.3
5.0
r
0.5
3.3
r
0.3
5.0
r
0.5
(Note 4)
V
CC
V
CC
Open
5.0V
(Note 5)
3
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