74AC257
QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
s
s
s
s
s
s
s
s
s
HIGH SPEED: t
PD
= 4.5ns (TYP.) at V
CC
= 5V
LOW POWER DISSIPATION:
I
CC
= 4µA(MAX.) at T
A
=25°C
HIGH NOISE IMMUNITY:
V
NIH
= V
NIL
= 28 % V
CC
(MIN.)
50Ω TRANSMISSION LINE DRIVING
CAPABILITY
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 24mA (MIN)
BALANCED PROPAGATION DELAYS:
t
PLH
≅
t
PHL
OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 2V to 6V
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 257
IMPROVED LATCH-UP IMMUNITY
DIP
SOP
TSSOP
ORDER CODES
PACKAGE
DIP
SOP
TSSOP
TUBE
74AC257B
74AC257M
DESCRIPTION
The 74AC257 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 four independent 2-channel
multiplexer with common SELECT and ENABLE
(OE) inputs. It is a non-inverting multiplexer. When
the OE input is held HIGH,all the output become in
PIN CONNECTION AND IEC LOGIC SYMBOLS
O
so
b
te
le
r
P
uc
od
s)
t(
bs
-O
high impedance state. If SELECT input is held
LOW, "A" data is selected, when SELECT input is
held HIGH, "B" data is chosen.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
et
l
o
P
e
od
r
s)
t(
uc
T&R
74AC257MTR
74AC257TTR
April 2001
1/11
74AC257
ABSOLUTE MAXIMUM RATINGS
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
Parameter
Value
-0.5 to +7
-0.5 to V
CC
+ 0.5
-0.5 to V
CC
+ 0.5
±
20
±
20
±
50
±
200
-65 to +150
300
Unit
V
V
V
mA
mA
mA
mA
°C
°C
I
CC
or I
GND
DC V
CC
or Ground Current
T
stg
Storage Temperature
T
L
Lead Temperature (10 sec)
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
Symbol
V
CC
V
I
V
O
T
op
dt/dv
Supply Voltage
Input Voltage
Output Voltage
Operating Temperature
Input Rise and Fall Time V
CC
= 3.0, 4.5 or 5.5V (note 1)
Parameter
Value
2 to 6
0 to V
CC
1) V
IN
from 30% to 70% of V
CC
O
so
b
te
le
r
P
uc
od
s)
t(
so
b
-O
te
le
r
P
0 to V
CC
8
-55 to 125
od
s)
t(
uc
Unit
V
V
V
°C
ns/V
3/11
74AC257
AC ELECTRICAL CHARACTERISTICS
(C
L
= 50 pF, R
L
= 500
Ω,
Input t
r
= t
f
= 3ns)
Test Condition
Symbol
Parameter
V
CC
(V)
3.3
(*)
5.0
(**)
3.3
(*)
5.0
(**)
3.3
(*)
5.0
(**)
3.3
(*)
5.0
(**)
T
A
= 25°C
Min.
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
Typ.
5.5
4.5
7.0
5.5
5.5
4.5
7.0
5.5
Max.
8.5
6.0
10.5
7.5
9.0
7.5
10.0
9.0
Value
-40 to 85°C
Min.
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
Max.
9.0
7.0
11.5
8.5
100
8.5
11.0
10.0
-55 to 125°C
Min.
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
Max.
9.0
7.0
11.5
8.5
100
8.5
13.0
11.0
ns
ns
Unit
t
PLH
t
PHL
Propagation Delay
Time
A, B to Y
t
PLH
t
PHL
Propagation Delay
Time
SELECT to Y
t
PZL
t
PZH
Output Enable
Time
t
PLZ
t
PHZ
Output Disable
Time
(*) Voltage range is 3.3V
±
0.3V
(**) Voltage range is 5.0V
±
0.5V
ns
ns
CAPACITIVE CHARACTERISTICS
Test Condition
Symbol
Parameter
V
CC
(V)
5.0
5.0
5.0
T
A
= 25°C
Min.
Typ.
5
8
Value
C
IN
C
OUT
C
PD
Input Capacitance
Output
Capacitance
Power Dissipation
Capacitance (note
1)
f
IN
= 10MHz
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
/4 (per circuit)
O
so
b
te
le
r
P
uc
od
s)
t(
bs
-O
et
l
o
20
Max.
P
e
Min.
-40 to 85°C
od
r
Max.
s)
t(
uc
Unit
Max.
pF
pF
pF
-55 to 125°C
Min.
5/11
模拟电子
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
