74VHCT257A
Quad 2 channel multiplexer (3-state)
Datasheet
−
production data
Features
■
High speed: t
PD
= 4.8 ns (typ.) at V
CC
= 5 V
■
Low power dissipation
I
CC
= 4
μA
(max.) at T
A
= 25 °C
■
■
■
■
■
■
■
■
Compatible with TTL outputs
V
IH
= 2 V (min.), V
IL
= 0.8 V (max.)
Power-down protection on inputs and outputs
Symmetrical output impedance
|I
OH
| = I
OL
= 8 mA (min.)
Balanced propagation delays: t
PLH
≅
t
PHL
Operating voltage range: V
CC(opr)
= 4.5 to 5.5 V
Pin and function compatible with 74 series 257
Improved latch-up immunity
Low noise: V
OLP
= 0.8 V (max.)
Table 1.
SO-16
Order code
Package
SO-16
Description
The 74VHCT257A is an advanced high-speed
CMOS quad 2 channel multiplexer (3-state)
fabricated with sub-micron silicon gate and
double-layer metal wiring C
2
MOS technology.
bs
O
It is composed of four independent 2 channel
multiplexers with common select and enable input
(OE). The VHCT257A is a non-inverting
multiplexer.
et
l
o
ro
P
e
uc
d
s)
t(
O
-
When the enable input is held “high”, all outputs
become high impedance state. If the select input
is held “low”, “A” data is selected, when select
input is “high”, “B” data is chosen.
Power-down protection is provided on all inputs
and outputs and 0 to 7 V can be accepted on
inputs with no regard to the supply voltage. This
device can be used to interface 5 V to 3 V since
all inputs are equipped with TTL threshold.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2 KV ESD immunity and transient excess
voltage.
so
b
te
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ro
P
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d
s)
t(
Tape and reel
74VHCT257AMTR
Figure 1.
Pin connection and IEC logic symbols
November 2012
This is information on a product in full production.
Doc ID 7073 Rev 4
1/15
www.st.com
1
74VHCT257A
Pin settings
2
Pin settings
Table 2.
Pin No
1
2, 5, 11, 14
3, 6, 10, 13
4, 7, 9, 12
15
8
16
Pin description
Symbol
SELECT
1A to 4A
1B to 4B
1Y to 4Y
OE
GND
V
CC
Name and function
Common data select inputs
Data inputs from source A
Data inputs from source B
3-state multiplexer outputs
3-state output enable inputs (active LOW)
Ground (0 V)
Positive supply voltage
Table 3.
Truth table
Inputs
OE
H
L
L
L
L
1. “Don’t care”.
SELECT
X
(1)
L
L
A
2. High impedance.
bs
O
et
l
o
ro
P
e
uc
d
s)
t(
H
H
O
-
so
b
X
(1)
L
H
X
(1)
X
(1)
te
le
ro
P
B
X
(1)
X
(1)
X
(1)
L
H
uc
d
s)
t(
Y
Z
(2)
L
H
L
H
Output
Doc ID 7073 Rev 4
3/15
74VHCT257A
Maximum ratings
3
Maximum ratings
Table 4.
Symbol
V
CC
V
I
V
O
V
O
I
IK
I
OK
I
O
I
CC
or
I
GND
T
stg
T
L
Supply voltage
DC input voltage
DC output voltage
(1)
DC output voltage
(2)
DC input diode current
DC output diode current
DC output current
DC V
CC
or ground current
Storage temperature
Lead temperature (10 sec.)
Absolute maximum ratings
Parameter
Value
-0.5 to +7.0
-0.5 to +7.0
-0.5 to +7.0
-0.5 to V
CC
+ 0.5
- 20
±
20
±
25
Unit
V
V
V
V
mA
mA
mA
1. Absolute maximum ratings are those values beyond which damage to the device may occur. Functional
operation under these conditions is not implied: output in OFF state.
2. Absolute maximum ratings are those values beyond which damage to the device may occur. Functional
operation under these conditions is not implied: high or low state.
Table 5.
Symbol
V
CC
V
I
Recommended operating conditions
Supply voltage
Input voltage
bs
O
et
l
o
r
P
e
V
O
V
O
T
op
Output voltage
(1)
Output voltage
(2)
Operating temperature
Input rise and fall time
(3)
(V
CC
= 5.0
±
0.5 V)
od
uc
s)
t(
O
-
s
b
te
le
o
ro
P
±
50
uc
d
300
s)
t(
mA
°C
°C
-65 to +150
Parameter
Value
4.5 to 5.5
0 to 5.5
0 to 5.5
0 to V
CC
-55 to 125
0 to 20
Unit
V
V
V
V
°C
ns/V
dt/dv
1. Output in OFF state.
2. High or low state.
3. V
IN
from 0.8 V to 2 V.
Doc ID 7073 Rev 4
5/15
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