DM74LS258BN ,TRI-STATE Quad 2-Data Selectors/MultiplexersFeaturesYTRI-STATE versions LS157 and LS158 with same pin-These Schottky-clamped high-performance m ..
DM74LS259M ,8-Bit Addressable LatchesDM74LS259 8-Bit Addressable LatchesAugust 1986Revised March 2000DM74LS2598-Bit Addressable Latches
DM74LS259N ,8-Bit Addressable LatchesFeaturesThese 8-bit addressable latches are designed for general 8-Bit parallel-out storage regist ..
DM74LS259WM ,8-Bit Addressable Latches
DM74LS266MX , Quad 2-Input Exclusive NOR Gate with Open Collector OutputsGeneral DescriptionThis device contains four independent gates each of whichperforms the logic excl ..
DM74LS266N ,QUAD 2-INPUT EXCLUSIVE-NOR GATE WITH OPEN-COLLECTOR OUTPUTSGeneral Description
This device contains four independent gates each of which
performs the logi ..
DS21S07AS ,SCSI TerminatorFEATURES Fully Compliant with SCSI-1, Fast SCSI, and Ultra SCSI Backward Compatible to the DS2107 ..
DS21S07AS/TR , SCSI Terminator
DS21T05 ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS21T05 consists of a bandgap reference, buffer amplifier, and nine termi ..
DS21T05Z+ ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS21T05 consists of a bandgap reference, buffer amplifier, and nine termi ..
DS21T06 , SCSI Terminator
DS21T07 ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS21T07 consists of a bandgap reference, buffer amplifier, and nine termi ..
54LS257A-54LS257ADMQB-DM74LS257BM-DM74LS258BN
TRI-STATE Quad 2-Data Selectors/Multiplexers
TL/F/6417
54LS257A/DM54LS257B/DM74LS257B,
54LS258A/DM54LS258B/DM74LS258B
TRI-STATE
Quad
2-Data
Selectors/Multiplexers
June 1989
54LS257A/DM54LS257B/DM74LS257B,
54LS258A/DM54LS258B/DM74LS258B
TRI-STATEÉ Quad 2-Data Selectors/Multiplexers
General Description
These Schottky-clamped high-performance multiplexers
feature TRI-STATE outputs thatcan interface directly with
data linesof bus-organized systems. Withallbutoneofthe
common outputs disabled(ata high impedance state),the
low impedanceofthe single enabled outputwill drivethe
buslineto ahigh orlow logic level.To minimizethe possibil-
ity thattwo outputswill attemptto takea commonbusto
opposite logic levels,the output enable circuitryis designed
suchthatthe output disable timesare shorter thantheout-
put enable times.
This TRI-STATE output feature meansthat n-bit (paralleled)
data selectorswithupto258 sourcescanbe implemented
for data buses.It also permitstheuseof standard TTLreg-
istersfor data retention throughoutthe system.
Features TRI-STATE versions LS157 and LS158 with same pin-
outs Schottky-clampedfor significant improvementin A-C
performance Provides bus interface from multiple sourcesin high-
performance systems Average propagation delay from data input12ns Typical power dissipation
LS257B 50 mW
LS258B 35 mW Alternate military/aerospace devices (54LS257A/
54LS258A)are available. Contacta National Semicon-
ductor Sales Office/Distributorfor specifications.
Connection Diagrams
Dual-In-Line Package
TL/F/6417–1
Order Number 54LS257ADMQB, 54LS257AFMQB,
54LS257ALMQB,DM54LS257BJ, DM54LS257BW,
DM74LS257BMor DM74LS257BN
SeeNS Package Number E20A, J16A,
M16A, N16Eor W16A
Dual-In-Line Package
TL/F/6417–2
Order Number 54LS258ADMQB, 54LS258AFMQB,
54LS258ALMQB, DM54LS258BJ, DM54LS258BW,
DM74LS258BMor DM74LS258BN
SeeNS Package Number E20A, J16A,
M16A,N16EorW16A
Function Table
Inputs OutputY
Output SelectAB LS257 LS258Control XX Z Z LX L H HX H L XL L H XH H LeHigh Level,LeLow Level,Xe Don’t Care,e HighImpedance(off)
TRI-STATEÉ isaregistered trademarkof National SemiconductorCorporation.
C1995National SemiconductorCorporation RRD-B30M105/PrintedinU.S.A.
