1/11
April 2001
s
HIGH SPEED: t
PD
= 5 ns (TYP.) at V
CC
= 5V
s
LOW POWER DISSIPATION:
I
CC
= 4
A(MAX.) at T
A
=25C
s
COMPATIBLE WITH TTL OUTPUTS
V
IH
= 2V (MIN.), V
IL
= 0.8V (MAX.)
s
50
TRANSMISSION LINE DRIVING
CAPABILITY
s
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 24mA (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 257
s
IMPROVED LATCH-UP IMMUNITY
DESCRIPTION
The 74ACT257 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 tecnology.
It is composed of an independent 2-channel
multiplexer with common SELECT and ENABLE
(OE)inputs. It is a non-inverting multiplexer. When
the ENABLE input is held HIGH, the outputs are
forced to a high impedance state. When the
SELECT input is held LOW, "A" data is selected;
when SELECT input is held HIGH, "B" data is
selected.
The device is designed to interface directly High
Speed CMOS systems with TTL, NMOS and
CMOS output voltage levels.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
74ACT257
QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
PIN CONNECTION AND IEC LOGIC SYMBOLS
ORDER CODES
PACKAGE
TUBE
T & R
DIP
74ACT257B
SOP
74ACT257M
74ACT257MTR
TSSOP
74ACT257TTR
TSSOP
DIP
SOP
74ACT257
2/11
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
TRUTH TABLE
X : Don't Care
Z : High Impedance
LOGIC DIAGRAM
This logic diagram has not be used to estimate propagation delays
PIN No
SYMBOL
NAME AND FUNCTION
1
SELECT
Common Data Select
Inputs
2, 5, 11, 14
1A to 4A
Data Inputs From Source
A
3, 6, 10, 13
1B to 4B
Data Inputs From Source
B
4, 7, 9, 12
1Y to 4Y
Multiplexer Outputs
15
OE
3 State Output Enable
Inputs (Active LOW)
8
GND
Ground (0V)
16
V
CC
Positive Supply Voltage
INPUTS
OUTPUT
OE
SELECT
A
B
Y
H
X
X
X
Z
L
L
L
X
L
L
L
H
X
H
L
H
X
L
L
L
H
X
H
H
74ACT257
3/11
ABSOLUTE MAXIMUM RATINGS
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
1) V
IN
from 0.8V to 2.0V
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
-0.5 to +7
V
V
I
DC Input Voltage
-0.5 to V
CC
+ 0.5
V
V
O
DC Output Voltage
-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
50
mA
I
CC
or I
GND
DC V
CC
or Ground Current
200
mA
T
stg
Storage Temperature
-65 to +150
C
T
L
Lead Temperature (10 sec)
300
C
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
4.5 to 5.5
V
V
I
Input Voltage
0 to V
CC
V
V
O
Output Voltage
0 to V
CC
V
T
op
Operating Temperature
-55 to 125
C
dt/dv
Input Rise and Fall Time V
CC
= 4.5 to 5.5V (note 1)
8
ns/V
74ACT257
4/11
DC SPECIFICATIONS
1) Maximum test duration 2ms, one output loaded at time
2) Incident wave switching is guaranteed on trasmission lines with impedances as low as 50
AC ELECTRICAL CHARACTERISTICS (C
L
= 50 pF, R
L
= 500
, Input t
r
= t
f
= 3ns)
(*) Voltage range is 5.0V
0.5V
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
V
IH
High Level Input
Voltage
4.5
V
O
= 0.1 V or
V
CC
-0.1V
2.0
1.5
2.0
2.0
V
5.5
2.0
1.5
2.0
2.0
V
IL
Low Level Input
Voltage
4.5
V
O
= 0.1 V or
V
CC
-0.1V
1.5
0.8
0.8
0.8
5.5
1.5
0.8
0.8
0.8
V
V
OH
High Level Output
Voltage
4.5
I
O
=-50
A
4.4
4.49
4.4
4.4
5.5
I
O
=-50
A
5.4
5.49
5.4
5.4
4.5
I
O
=-24 mA
3.86
3.76
3.7
V
5.5
I
O
=-24 mA
4.86
4.76
4.7
V
OL
Low Level Output
Voltage
4.5
I
O
=50
A
0.001
0.1
0.1
0.1
5.5
I
O
=50
A
0.001
0.1
0.1
0.1
4.5
I
O
=24 mA
0.36
0.44
0.5
5.5
I
O
=24 mA
0.36
0.44
0.5
I
I
Input Leakage Cur-
rent
5.5
V
I
= V
CC
or GND
0.1
1
1
A
I
OZ
High Impedance
Output Leakege
Current
5.5
V
I
= V
IH
or V
IL
V
O
= V
CC
or GND
0.5
5
5
mA
I
CCT
Max I
CC
/Input
5.5
V
I
= V
CC
- 2.1V
0.6
1.5
1.6
mA
I
CC
Quiescent Supply
Current
5.5
V
I
= V
CC
or GND
4
40
80
A
I
OLD
Dynamic Output
Current (note 1, 2)
5.5
V
OLD
= 1.65 V max
75
50
mA
I
OHD
V
OHD
= 3.85 V min
-75
-50
mA
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
t
PLH
t
PHL
Propagation Delay
Time A, B to Y
5.0
(*)
5.0
8.0
9.0
9.0
ns
t
PLH
t
PHL
Propagation Delay
Time SELECT to Y
5.0
(*)
6.0
9.0
10.0
10.0
ns
t
PZL
t
PZH
Output Enable
Time
5.0
(*)
5.0
8.0
9.0
9.0
ns
t
PLZ
t
PHZ
Output Disable
Time
5.0
(*)
6.0
9.0
10.0
10.0
ns
74ACT257
5/11
CAPACITIVE CHARACTERISTICS
1) C
PD
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. I
CC(opr)
= C
PD
x V
CC
x f
IN
+ I
CC
/n (per
circuit)
TEST CIRCUIT
C
L
= 50pF or equivalent (includes jig and probe capacitance)
R
L
= R
1
= 500
or equivalent
R
T
= Z
OUT
of pulse generator (typically 50
)
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
C
IN
Input Capacitance
5.0
5
pF
C
OUT
Output
Capacitance
5.0
8
pF
C
PD
Power Dissipation
Capacitance (note
1)
5.0
f
IN
= 10MHz
25
pF
TEST
SWITCH
t
PLH
, t
PHL
Open
t
PZL
, t
PLZ
2V
CC
t
PZH
, t
PHZ
Open
74ACT257
6/11
WAVEFORM 1: PROPAGATION DELAYS FOR INVERTING CONDITIONS (f=1MHz; 50% duty cycle)
WAVEFORM 2: PROPAGATION DELAYS FOR NON-INVERTING CONDITIONS (f=1MHz; 50% duty
cycle)
74ACT257
7/11
WAVEFORM 3: OUTPUT ENABLE AND DISABLE TIME (f=1MHz; 50% duty cycle)
74ACT257
8/11
DIM.
mm
inch
MIN.
TYP.
MAX.
MIN.
TYP.
MAX.
a1
0.51
0.020
B
0.77
1.65
0.030
0.065
b
0.5
0.020
b1
0.25
0.010
D
20
0.787
E
8.5
0.335
e
2.54
0.100
e3
17.78
0.700
F
7.1
0.280
I
5.1
0.201
L
3.3
0.130
Z
1.27
0.050
P001C
Plastic DIP-16 (0.25) MECHANICAL DATA
74ACT257
9/11
DIM.
mm
inch
MIN.
TYP.
MAX.
MIN.
TYP.
MAX.
A
1.75
0.068
a1
0.1
0.2
0.004
0.007
a2
1.65
0.064
b
0.35
0.46
0.013
0.018
b1
0.19
0.25
0.007
0.010
C
0.5
0.019
c1
45 (typ.)
D
9.8
10
0.385
0.393
E
5.8
6.2
0.228
0.244
e
1.27
0.050
e3
8.89
0.350
F
3.8
4.0
0.149
0.157
G
4.6
5.3
0.181
0.208
L
0.5
1.27
0.019
0.050
M
0.62
0.024
S
8 (max.)
P013H
SO-16 MECHANICAL DATA
74ACT257
10/11
DIM.
mm
inch
MIN.
TYP.
MAX.
MIN.
TYP.
MAX.
A
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
0.20
0.0035
0.0079
D
4.9
5
5.1
0.193
0.197
0.201
E
6.25
6.4
6.5
0.246
0.252
0.256
E1
4.3
4.4
4.48
0.169
0.173
0.176
e
0.65 BSC
0.0256 BSC
K
0
o
4
o
8
o
0
o
4
o
8
o
L
0.50
0.60
0.70
0.020
0.024
0.028
c
E
b
A2
A
E1
D
1
PIN 1 IDENTIFICATION
A1
L
K
e
TSSOP16 MECHANICAL DATA
74ACT257
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
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11/11
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