74VHCT245A
OCTAL BUS
TRANSCEIVER (3-STATE)
PRELIMINARY DATA
August 1999
ORDER CODES :
74VHCT245AM
74VHCT245AT
M
(Micro Package)
s
HIGH SPEED: t
PD
= 4.5 ns (TYP.) at V
CC
= 5V
s
LOW POWER DISSIPATION:
I
CC
= 4
A (MAX.) at T
A
= 25
o
C
s
COMPATIBLE WITH TTL OUTPUTS:
V
IH
= 2V (MIN), V
IL
= 0.8V (MAX)
s
POWER DOWN PROTECTION ON INPUTS &
OUTPUTS
s
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 8 mA (MIN)
s
BALANCED PROPAGATION DELAYS:
t
PLH
t
PHL
s
OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 4.5V to 5.5V
s
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 245
s
IMPROVED LATCH-UP IMMUNITY
s
LOW NOISE: V
OLP
= 0.9V (Max.)
DESCRIPTION
The 74VHCT245A 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 technology.
This IC is intended for two-way asynchronous
communication
between
data
busses;
the
direction of data trasmission is determined by the
T
(TSSOP Package)
level of the DIR input. The enable input G can be
used to disable the device so that the busses are
effectively isolated.
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 TERMINAL IS FLOATING
(HIGH IMPEDANCE STATE) IT IS REQUESTED
TO FIX THE INPUT LEVEL BY MEANS OF
EXTERNAL
PULL
DOWN
OR
PULL
UP
RESISTOR.
PIN CONNECTION AND IEC LOGIC SYMBOLS
1/9
INPUT/OUTPUT EQUIVALENT CIRCUIT
INPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
SYMBOL
NAME AND FUNCT ION
1
DIR
Directional Control
2, 3, 4, 5,
6, 7, 8, 9
A1 to A8
Data Inputs/Outputs
18, 17, 16,
15, 14, 13,
12, 11
B1 to B8
Data Inputs/Outputs
19
G
Output Enable Input
10
GND
Ground (0V)
20
V
CC
Positive Supply Voltage
TRUTH TABLE
INPUT
F UNCTI ON
OUT PUT
G
DIR
A BUS
B BUS
L
L
OUTPUT
INPUT
A = B
L
H
INPUT
OUTPUT
B = A
H
X
Z
Z
Z
X:"H" or "L"
Z: High impedance
74VHCT245A
2/9
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Val ue
Unit
V
CC
Supply Voltage
-0.5 to +7.0
V
V
I
DC Input Voltage (DIR, G)
-0.5 to +7.0
V
V
I/O
DC Bus I/O Voltage (see note 1)
-0.5 to +7.0
V
V
I/O
DC Bus I/O Voltage (see note 2)
-0.5 to V
CC
+ 0.5
V
I
IK
DC Input Diode Current
- 20
mA
I
OK
DC Output Diode Current
20
mA
I
O
DC Output Current
25
mA
I
CC
or I
GND
DC V
CC
or Ground Current
75
mA
T
stg
Storage Temperature
-65 to +150
o
C
T
L
Lead Temperature (10 sec)
300
o
C
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied.
1) Output in OffState
2) High or Low State. I
O
absolute maximum rating must be observed.
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Valu e
Uni t
V
CC
Supply Voltage
4.5 to 5.5
V
V
I
Input Voltage (DIR, G)
0 to 5.5
V
V
I/O
Bus I/O Voltage (see note 1)
0 to 5.5
V
V
I/O
Bus I/O Voltage (see note 2)
0 to V
CC
V
T
op
Operating Temperature
-40 to +85
o
C
dt/dv
Input Rise and Fall Time (see note 3) (V
CC
= 5.0
0.5V)
0 to 20
ns/V
1) Output in OffState
2) High or Low State. I
O
absolute maximum rating must be observed.
3) V
IN
from 0.8 to 2V
74VHCT245A
3/9
DC SPECIFICATIONS
Symb ol
Parameter
T est Cond ition s
Val ue
Un it
V
CC
(V)
T
A
= 25
o
C
-40 to 85
o
C
Min.
Typ .
Max.
Min .
Max.
V
IH
High Level Input
Voltage
4.5 to 5.5
2
2
V
V
IL
Low Level Input
Voltage
4.5 to 5.5
0.8
0.8
V
V
OH
High Level Output
Voltage
4.5
I
O
=-50
A
4.4
4.5
4.4
V
4.5
I
O
=-8 mA
3.94
3.8
V
OL
Low Level Output
Voltage
4.5
I
O
=50
A
0.0
0.1
0.1
V
4.5
I
O
=8 mA
0.36
0.44
I
OZ
High Impedance
Output Leakage
Current
5.5
V
I
= V
IH
or V
IL
V
O
= 0V to 5.5V
0.25
2.5
A
I
I
Input Leakage Current
0 to 5.5
V
I
= 5.5V or GND
0.1
1.0
A
I
CC
Quiescent Supply
Current
5.5
V
I
= V
CC
or GND
4
40
A
I
CC
Additional Worst Case
Supply Current
5.5
One Input at 3.4V,
other input at V
CC
or
GND
1.35
1.5
mA
I
OPD
Output Leakage
Current
0
V
OUT
= 5.5V
0.5
5.0
A
AC ELECTRICAL CHARACTERISTICS (Input t
r
= t
f
=3 ns)
Symb ol
Parameter
Test Co nditi on
Val ue
Un it
V
CC
(*)
(V)
C
L
(pF)
T
A
= 25
o
C
-40 to 85
o
C
Min.
Typ .
Max.
Min .
Max.
t
PLH
t
PHL
Propagation Delay
Time
5.0
15
4.5
7.5
1.0
8.5
ns
5.0
50
5.5
8.5
1.0
9.5
t
PZL
t
PZH
Output Enable Time
5.0
15
R
L
= 1K
9.0
14.5
1.0
15.5
ns
5.0
50
10.0
15.5
1.0
16.5
t
PLZ
t
PHZ
Output Disable Time
5.0
50
R
L
= 1K
9.5
15.0
1.0
16.0
ns
t
OSLH
t
OSHL
Output to Output Skew
Time (note 1)
5.0
50
1.0
1.0
ns
(*) Voltage range is 5V
0.5V
Note 1: Parameter guaranteed by design. t
soLH
= |t
pLHm
- t
pLHn
|, t
soHL
= |t
pHLm
- t
pHLn
|
74VHCT245A
4/9
CAPACITIVE CHARACTERISTICS
Symb ol
Parameter
Test Co nditi ons
Valu e
Un it
T
A
= 25
o
C
-40 to 85
o
C
Min.
T yp.
Max.
Mi n.
Max.
C
IN
Input Capacitance
4
10
10
pF
C
I/O
Bus Input Capacitance
8
pF
C
PD
Power Dissipation
Capacitance (note 1)
13
pF
1) C
PD
isdefined as the value of the IC'sinternal equivalent capacitance which is calculated fromthe operating current consumption without load. (Referto
Test Circuit).Average operting current can be obtained by the following equation. I
CC
(opr) = C
PD
V
CC
f
IN
+ I
CC
/8(per circuit)
TEST CIRCUIT
T EST
SW IT CH
t
PLH
, t
PHL
Open
t
PZL
, t
PLZ
V
CC
t
PZH
, t
PHZ
GND
C
L
= 15/50 pF or equivalent (includes jig and probe capacitance)
R
L
= R
1
= 1K
orequivalent
R
T
= Z
OUT
of pulse generator (typically 50
)
DYNAMIC SWITCHING CHARACTERISTICS
Symb ol
Parameter
T est Cond ition s
Val ue
Un it
V
CC
(V)
T
A
= 25
o
C
-40 to 85
o
C
Min.
Typ .
Max.
Min .
Max.
V
OLP
Dynamic Low Voltage
Quiet Output (note 1, 2)
5.0
C
L
= 50 pF
0.6
0.9
V
V
OLV
-0.9
-0.6
V
IHD
Dynamic High Voltage
Input (note 1, 3)
5.0
2
V
IL D
Dynamic Low Voltage
Input (note 1, 3)
5.0
0.8
1) Worst case package.
2) Max number of outputs defined as (n). Data inputs are driven 0V to 3.0V, (n -1) outputs switching and one output at GND.
3) Max number of data inputs (n) switching. (n-1) switching 0V to3.0V. Inputs under test switching: 3.0V to threshold (V
ILD
), 0V to threshold (V
IHD
), f=1MHz.
74VHCT245A
5/9
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