Fairchild Semiconductor 74AC257SJX, 74AC257SJ, 74AC257SCX, 74AC257SC, 74AC257PC Datasheet
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© 1999 Fairchild Semiconductor Corporation DS009949 www.fairchildsemi.com
November 1988
Revised November 1999
74AC257 • 74ACT257 Quad 2-Input Multiplexer with 3-STATE Outputs
74AC257 • 74ACT257
Quad 2-Input Multiplexer with 3-STATE Outputs
General Description
The AC/ACT257 is a quad 2-input multiplexer with 3STATE outputs. Four bits of data from two sources can be
selected using a Com mon Dat a Sele ct in put. Th e four outputs present the sel ected data in true (noninverted) for m.
The outputs may be switched to a high impedance state by
placing a logic HIGH on the commo n Output Enable (OE
)
input, allowing the outpu ts to i nt erf ace d irectly with bus-oriented systems.
Features
■ ICC and IOZ reduced by 5 0%
■ Multiplexer expansion by tying outputs together
■ Noninverting 3-STATE outputs
■ Outputs source/sink 24 mA
■ ACT257 has TTL-compatible inputs
Ordering Code:
Device also available in Tape and Reel. Specify by appending su ffix le tter “X” to the ordering code.
Logic Symbols
IEEE/IEC
Connection Diagram
Pin Descriptions
FACT is a trademark of Fairchild Semiconductor Corporation.
Order Number Package Number Package Description
74AC257SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74AC257SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74AC257MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74AC257PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
74ACT257SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74ACT257SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74ACT257MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74ACT257PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
Pin Names Description
S Common Data Select Input
OE
3-STATE Output Enable Input
I
0a–I0d
Data Inputs from Source 0
I
1a–I1d
Data Inputs from Source 1
Z
a–Zd
3-STATE Multiplexer Outputs
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74AC257 • 74ACT257
Functional Description
The AC/ACT257 is quad 2-input multiplexer with 3-STATE
outputs. It selects fo ur bits of dat a from two so urces u nder
control of a Common Data Selec t input. When the Select
input is LOW, the I
0x
inputs are selected and when Select
is HIGH, the I
1x
inputs are selected. The data on the
selected inputs appears at the outputs in true (noninverted)
form. The device is the logic implementation of a 4-pole, 2position switch whe re the position of the switch is determined by the logic levels suppli ed to the Select inpu t. The
logic equations for the outputs are as follows:
Z
a
= OE • (11a • S + I0a • S)
Z
b
= OE • (11b • S + I0b • S)
Z
c
= OE • (11c • S + I0c • S)
Z
d
= OE • (11d • S + I0d • S)
When the Output Enab le (OE
) is HIGH, the outputs are
forced to a high impedance state. If the outp uts are tied
together, all but one device m ust be i n the hig h im pe dance
state to avoid h igh currents that wou ld exceed the maximum ratings. Designe rs should ensure th e Output Enable
signals to 3-STATE devices whose outputs are tied
together are designed so there is no overlap.
Tr uth Table
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = High Impedance
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
Output Select Data Outputs
Enable Input Inputs
OE
SI0I
1
Z
HXXXZ
LHXLL
LHXHH
LLLXL
LLHXH
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74AC257 • 74ACT257
Absolute Maximum Ratings(Note 1) Recommended Operating
Conditions
Note 1: Absolute max imum ratings are those values beyond w hich damage
to the device may occu r. The databook spe cificatio ns shou ld be met, wit hout exception, to ensure that the system de sign is relia ble over its p ower
supply, temperature, and output/input loading variables. Fairchild does not
recommend operation of FACT circuits outside databook specif ic at ions.
DC Electrical Characteristics for AC
Note 2: All outputs loaded; thres holds on input associate d w it h output under test.
Note 3: Maximum test duration 2.0 ms, one output loaded at a time.
Note 4: I
IN
and ICC @ 3.0V are guaranteed to be less than or equa l t o th e respective limit @ 5.5V VCC.
Supply Voltage (VCC) −0.5V to +7.0V
DC Input Diode Current (I
IK
)
V
I
= −0.5V −20 mA
V
I
= VCC +0.5V +20 mA
DC Input Voltage (V
I
) −0.5V to VCC + 0.5V
DC Output Diode Current (I
OK
)
V
O
= −0.5V −20 mA
V
O
= VCC +0.5V +20 mA
DC Output Voltage (V
O
) −0.5V to VCC + 0.5V
DC Output Source ort
Sink Curren (I
O
) ±50 mA
DC V
CC
or Ground Current
Per Output Pin (I
CC
or I
GND
) ±50 mA
Storage Temperature (T
STG
) −65°C to +150°C
Junction Temperature (T
J
)
PDIP 140°C
Supply Voltage (V
CC
)
AC 2.0V to 6.0V
ACT 4.5V to 5.5V
Input Voltage (V
I
)0V to V
CC
Output Voltage (VO)0V to V
CC
Operating Temperature (TA) −40°C to +85°C
Minimum Input Edge Rate (∆V/∆t)
AC Devices
V
IN
from 30% to 70% of V
CC
VCC @ 3.3V, 4.5V, 5.5V 125 mV/ns
Minimum Input Edge Rate (∆V/∆t)
ACT Devices
V
IN
from 0.8V to 2.0V
V
CC
@ 4.5V, 5.5V 125 mV/ns
Symbol Parameter
V
CC
TA = +25°CTA = −40°C to +85°C
Units Conditions
(V) Typ Guaranteed Limits
V
IH
Minimum HIGH Level 3.0 1.5 2.1 2.1 V
OUT
= 0.1V
Voltage Input 4.5 2.25 3.15 3.15 V or VCC − 0.1V
5.5 2.75 3.85 3.85
V
IL
Maximum LOW Level 3.0 1.5 0.9 0.9 V
OUT
= 0.1V
Voltage Input 4.5 2.25 1.35 1.35 V or VCC − 0.1V
5.5 2.75 1.65 1.65
V
OH
Minimum HIGH Level 3.0 2.99 2.9 2.9
Voltage Output 4.5 4.49 4.4 4.4 V I
OUT
= −50 µA
5.5 5.49 5.4 5.4
VIN = VIL or V
IH
3.0 2.56 2.46 IOH = −12 mA
4.5 3.86 3.76 V I
OH
= −24 mA
5.5 4.86 4.76 I
OH
= −24 mA (Note 2)
V
OL
Maximum LOW Level 3.0 0.002 0.1 0.1
Voltage Output 4.5 0.001 0.1 0.1 V I
OUT
= 50 µA
5.5 0.001 0.1 0.1
VIN = VIL or V
IH
3.0 0.36 0.44 IOL = 12 mA
4.5 0.36 0.44 V IOL = 24 mA
5.5 0.36 0.44 IOL = 24 mA (Note 2)
IIN (Note 4) Maximum Input Leakage Current 5.5 ± 0.1 ± 1.0 µAVI = VCC, GND
I
OZ
Maximum 3-STATE VI (OE) = VIL, V
IH
Leakage Current 5.5 ±0.25 ±2.5 µAVI = VCC, GND
VO = VCC, GND
I
OLD
Minimum Dynamic (Note 3) 5.5 75 mA V
OLD
= 1.65V Max
I
OHD
Output Current 5.5 −75 mA V
OHD
= 3.85V Min
I
CC
(Note 4) Maximum Quiescent Supply Current 5.5 4.0 40.0 µAVIN = VCC or GND
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