SGS Thomson Microelectronics 74AC257 Datasheet
74AC257
QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
■ HIGH SPEED: t
■ LOW POWE RDISSIPATION:
=8 µA (MAX.)atTA=25oC
I
CC
■ HIGHNOISEIMMUNITY:
V
NIH=VNIL
■ 50Ω TRANSMISSION LINE DRIVING
=28%VCC(MIN.)
=4.5ns (TYP.) at VCC=5V
PD
CAPABILITY
■ SYMMETRICALOUTPUT IMPEDANCE:
|I
|=IOL=24mA(MIN)
OH
■ BALANCEDPROPAGAT IONDELAYS:
t
≅ t
PLH
PHL
■ OPERATINGVOLTAGERAN GE:
V
(OPR )= 2V to 6V
CC
■ PIN AND FUNCTION COMPATIBLE WITH
74 SERIES257
■ IMPROVEDLATCH-UP IMMUNITY
DESCRIPTION
The AC257 is an advanced high-speed CMOS
QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
fabricated with sub-micron silicon gate and
double-layermetalwiring C
2
MOS technology.
It is ideal for low power applications mantaining
high speed operation similar to equivalent Bipolar
SchottkyTTL.
B
(Plastic Package)
(Micro Package)
M
ORDERCODES:
74AC257B
These IC’s are composed of an independent 2
channel multiplexer with common SELECT and
ENABLEINPUT.
TheAC257 is a noninverting multiplexer.
Whenthe ENABLE INPUT is held ”High”, outputs
of both IC’s become high impedance state. If
SELECT INPUT is held ”Low”, ”A” data is
selected, when SELECT INPUT is ”High”, ”B”
datais chosen.
All inputs and outputs are equipped with
protectioncircuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
PINCONNECTION AND IEC LOGIC SYMBOLS
April 1997
1/10
74AC257
INPUTAND OUTPUTEQUIVALENTCIRCUIT
TRUTH TABLE
INPUTS OUTPUTS
OESELECTABY
HXXXZ
LLLXL
LLHXH
LHXLL
LHXHH
X = DON’TCARE Z = HIGHIMPEDANCE
PIN DESCRIPTION
PI N No SYM B O L NAME A ND FUNCTI ON
1 SELECT Common Data Select Input
2, 5, 14, 11 1A to 4A Data Input From Source A
3, 6, 13, 10 1B to 4B Data Inputs from Source B
4, 7, 12, 9 1Y to 4Y 3 State Multiplexer Outputs
15 OE 3 State Output Enable
Inputs (Active LOW)
8 GND Ground (0V)
16 V
CC
Positive Supply Voltage
LOGICDIAGRAM
This logic diagram has not be used to estimate propagation delays
2/10
74AC257
ABSOLUTE MAXIMUMRATINGS
Symb o l Parame t er Val u e Uni t
V
V
V
I
I
OK
I
orI
I
CC
T
T
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied.
RECOMMENDEDOPERATINGCONDITIONS
Symb o l Parame t er Value Un i t
V
V
V
T
dt/dv Input Rise and Fall Time V
1) VINfrom 30%to70%of V
Supply Voltage -0.5 to +7 V
CC
DC Input Voltage -0.5 to VCC+ 0.5 V
I
DC Output Voltage -0.5 to VCC+ 0.5 V
O
DC Input Diode Current ± 20 mA
IK
DC Output Diode Current ± 20 mA
DC Output Current ± 50 mA
O
DC VCCor Ground Current ± 200 mA
GND
Storage Temperature -65 to +150
stg
Lead Temperature (10 sec) 300
L
Supply Voltage 2 to 6 V
CC
Input Voltage 0 to V
I
Output Voltage 0 to V
O
Operating Temperature: -40 to +85
op
= 3.0, 4.5 or 5.5 V(note 1) 8 ns/V
CC
CC
CC
CC
o
C
o
C
V
V
o
C
3/10
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