The Transmit/Receive (T/R) input determines the direction
of the data flow through the bidirectional transceivers.
Transmit (active HIGH) enables data from the A Port to the
B Port; Receive (active LOW) enables data from the B Port
to the A Port.
The Output Enable (OE) input disables the parity and
ERROR outputs and both the A and B Ports by placing
them in a HIGH-Z condition when the Output Enable input
is HIGH.
When transmitting (T/R HIGH), the parity generator detects
whether an even or odd number of bits on the A Port are
HIGH and compares these with the condition of the parity
select (ODD/EVEN). If the Parity Select is HIGH and an
even number of A inputs are HIGH, the Parity output is
HIGH.
In receiving mode (T/R LOW), the parity select and number
of HIGH inputs on port B are compared to the condition of
the Parity input. If an even number of bits on the B Port are
HIGH, the parity select is HIGH, and the PARITY input is
HIGH, then ERROR will be HIGH to indicate no error. If an
odd number of bits on the B Port are HIGH, the parity
select is HIGH, and the PARITY input is HIGH, the ERROR
will be LOW indicating an error.
Function Table
Number of
Inputs that
are HIGH
0, 2, 4, 6, 8
Inputs
OE T/R
L
L
L
L
L
L
1, 3, 5, 7
L
L
L
L
L
L
Immaterial
H
H
=
HIGH Voltage Level
L
=
LOW Voltage Level
X
=
Immaterial
Z
=
High Impedance
Function Table
Input/
Output
Outputs
OE
Outputs
Mode
Transmit
Transmit
Receive
Receive
Receive
Receive
Transmit
Transmit
Receive
Receive
Receive
Receive
Z
L
L
H
H
=
HIGH Voltage Level
L
=
LOW Voltage Level
X
=
Immaterial
Inputs
Outputs
T/R
L
H
X
Bus B Data to Bus A
Bus A Data to Bus B
High-Z State
ODD/
EVEN
H
L
H
H
L
L
H
L
H
H
L
L
X
Parity ERROR
H
L
H
L
H
L
L
H
H
L
H
L
Z
Z
Z
H
L
L
H
Z
Z
L
H
H
L
Z
H
H
L
L
L
L
H
H
L
L
L
L
X
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2
74F657
Functional Block Diagram
3
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74F657
Absolute Maximum Ratings
(Note 1)
Storage Temperature
Ambient Temperature under Bias
Junction Temperature under Bias
V
CC
Pin Potential to Ground Pin
Input Voltage (Note 2)
Input Current (Note 2)
Voltage Applied to Output
in HIGH State (with V
CC
=
0V)
Standard Output
3-STATE Output
Current Applied to Output
in LOW State (Max)
twice the rated I
OL
(mA)
−0.5V
to V
CC
−0.5V
to
+5.5V
−65°C
to
+150°C
−55°C
to
+125°C
−55°C
to
+150°C
−0.5V
to
+7.0V
−0.5V
to
+7.0V
−30
mA to
+5.0
mA
Recommended Operating
Conditions
Free Air Ambient Temperature
Supply Voltage
0°C to
+70°C
+4.5V
to
+5.5V
Note 1:
Absolute maximum ratings are values beyond which the device
may be damaged or have its useful life impaired. Functional operation
under these conditions is not implied.
Note 2:
Either voltage limit or current limit is sufficient to protect inputs.
DC Electrical Characteristics
Symbol
V
IH
V
IL
V
CD
V
OH
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Clamp Diode Voltage
Output HIGH
Voltage
10% V
CC
10% V
CC
10% V
CC
5% V
CC
5% V
CC
V
OL
Output LOW
Voltage
I
IH
Input HIGH
Current
I
BVI
I
BVIT
I
IL
Input HIGH Current
Breakdown Test
Input HIGH Current
Breakdown Test (I/O)
Input LOW
Current
I
OZH
I
OZL
I
IH
+
I
OZH
I
IL
+
I
OZL
I
OS
Output Leakage Current
Output Leakage Current
Output Leakage
Current
Output Leakage
Current
Output Short-Circuit
Current
I
CEX
Output HIGH Leakage
Current
−60
−100
10% V
CC
10% V
CC
2.5
2.4
2.0
2.7
2.7
0.5
0.55
20
40
100
1.0
2.0
−20
−40
50
−50
70
90
−70
−90
−150
−225
250
1.0
2.0
I
ZZ
I
CCH
I
CCL
I
CCZ
Bus Drainage Test
Power Supply Current
Power Supply Current
Power Supply Current
101
112
109
500
125
150
145
V
µA
µA
mA
µA
µA
µA
µA
µA
mA
µA
mA
mA
µA
mA
mA
mA
Min
V
Min
Min
2.0
0.8
−1.2
Typ
Max
Units
V
V
V
Min
V
CC
Conditions
Recognized as a HIGH Signal
Recognized as a LOW Signal
I
IN
= −18
mA
I
OH
= −1
mA (A
n
)
I
OH
= −3
mA (A
n
B
n
, Parity, ERROR)
I
OH
= −15
mA (B
n
, Parity, ERROR)
I
OH
= −1
mA (A
n
)
I
OH
= −3
mA (A
n
, B
n
, Parity, ERROR)
I
OL
=
24 mA (A
n
)
I
OL
=
64 mA (B
n
Parity, ERROR)
V
IN
=
2.7V (ODD/EVEN)
V
IN
2.7V (T/R, OE)
V
IN
=
7.0V (T/R, OE, ODD/EVEN)
V
IN
=
5.5V (Parity, B
n
)
V
IN
=
5.5V (A
n
)
V
IN
=
0.5V (ODD/EVEN)
V
IN
=
0.5V (T/R, OE)
V
OUT
=
2.7V (ERROR)
V
OUT
=
0.5V (ERROR)
V
I/O
=
2.7V (B
n
, Parity)
V
I/O
=
2.7V (A
n
)
V
I/O
=
0.5V (B
n
, Parity)
V
I/O
=
0.5V (A
n
)
V
OUT
=
0V (A
n
)
V
OUT
=
0V (B
n
, Parity, ERROR)
V
OUT
=
V
CC
(ERROR)
V
OUT
=
V
CC
(B
n
, Parity)
V
OUT
=
V
CC
(A
n
)
V
OUT
=
5.25V (A
n
, B
n
, Parity, ERROR)
V
O
=
HIGH
V
O
=
LOW
V
O
=
HIGH Z
Max
V
CC
=
0
Max
Max
Max
Max
Max
Max
Max
Max
Max
Max
0.0V
Max
Max
Max
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4
74F657
AC Electrical Characteristics
T
A
= +25°C
Symbol
Parameter
Min
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
t
PZH
t
PZL
t
PHZ
t
PLZ
t
PZH
t
PZL
t
PHZ
t
PLZ
Propagation Delay
A
n
to B
n
, B
n
to A
n
Propagation Delay
A
n
to Parity
Propagation Delay
ODD/EVEN to PARITY
Propagation Delay
ODD/EVEN to ERROR
Propagation Delay
B
n
to ERROR
Propagation Delay
PARITY to ERROR
Output Enable Time
OE to A
n
/B
n
Output Disable Time
OE to A
n
/B
n
Output Enable Time
OE to ERROR (Note 3)
Output Disable Time
OE to ERROR
Output Enable Time
OE to PARITY
Output Disable Time
OE to PARITY
2.5
3.0
6.5
7.0
4.5
4.5
4.5
4.5
8.0
8.0
7.0
7.5
3.0
4.0
1.0
1.0
3.0
4.0
1.0
1.0
3.0
4.0
1.0
1.0
V
CC
= +5.0V
C
L
=
50 pF
Typ
4.5
4.9
10.1
10.9
7.8
8.8
7.5
8.2
14.0
15.0
10.8
11.8
5.0
6.5
4.5
4.9
5.0
7.7
4.5
4.9
5.0
7.7
4.6
5.1
Max
8.0
7.5
14.0
15.0
11.0
12.0
11.0
12.0
20.5
21.5
15.5
16.5
8.0
10.0
8.0
7.5
8.0
10.0
8.0
7.5
8.0
10.0
8.0
7.5
T
A
= −55°C
to
+125°C
V
CC
= +5.0V
C
L
=
50 pF
Min
2.5
3.0
5.5
5.5
4.0
4.5
4.0
4.5
7.5
7.5
6.0
6.5
2.5
3.5
1.0
1.0
2.5
3.5
1.0
1.0
2.5
3.5
1.0
1.0
Max
9.5
8.5
18.0
20.5
14.0
16.5
14.0
16.5
27.0
28.5
20.0
22.0
11.0
13.5
9.5
8.5
11.0
13.5
9.5
8.5
11.0
13.5
9.5
8.5
T
A
=
0°C to
+70°C
V
CC
= +5.0V
C
L
=
50 pF
Min
2.5
3.0
6.0
6.0
4.0
4.5
4.0
4.5
7.5
7.5
6.0
7.5
2.5
3.5
1.0
1.0
2.5
3.5
1.0
1.0
2.5
3.5
1.0
1.0
Max
9.0
8.0
16.0
16.5
13.0
13.5
13.0
13.5
23.0
23.5
17.0
18.5
9.5
11.0
9.0
8.0
9.5
11.0
9.0
8.0
9.5
11.0
9.0
8.0
ns
ns
ns
Units
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 3:
These delay times reflect the 3-STATE recovery time only and not the signal time through the buffers or the parity check circuity. To assure VALID
information at the ERROR pin, time must be allowed for the signal to propagate through the drivers (B to A), through the parity check circuitry (same as A to
PARITY), and to the ERROR output after the ERROR pin has been enabled (Output Enable times). VALID data at the ERROR pin
