74Ls155

DM74LS155 • DM74LS156 Dual 2-Line to 4-Line Decoders/Demultiplexers

August 1986 Revised April 2000

DM74LS155 • DM74LS156 Dual 2-Line to 4-Line Decoders/Demultiplexers
General Description
These TTL circuits feature dual 1-line-to-4-line demultiplexers with individual strobes and common binary-address inputs in a single 16-pin package. When both sections are enabled by the strobes, thecommon address inputs sequentially select and route associated input data to the appropriate output of each section. The individual strobes permit activating or inhibiting each of the 4-bit sections as desired. Data applied to input C1 is inverted at its outputs and data applied at C2 is true through its outputs. The inverter following the C1 data input permits use as a 3-to-8line decoder, or1-to-8-line demultiplexer, without external gating. Input clamping diodes are provided on these circuits to minimize transmission-line effects and simplify system design.

Features
s Applications: Dual 2-to-4-line decoder Dual 1-to-4-line demultiplexer 3-to-8-line decoder 1-to-8-line demultiplexer s Individual strobes simplify cascading for decoding or demultiplexing larger words s Input clampingdiodes simplify system design s Choice of outputs: Totem-pole (DM74LS155) Open-collector (DM74LS156)

Ordering Code:
Order Number DM74LS155M DM74LS155N DM74LS156M DM74LS156N Package Number M16A N16E M16A N16E Package Description 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide 16-Lead Small OutlineIntegrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.

Connection Diagram

© 2000 Fairchild Semiconductor Corporation

DS006395

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DM74LS155 • DM74LS156

Function Tables
3-Line-to-8-LineDecoder or 1-Line-to-8-Line Demultiplexer Inputs Select C (Note 1) X L L L L H H H H B X L L H H L L H H A X L H L H L H L H Strobe Or Data G (Note 2) H L L L L L L L L (0) 2Y0 H L H H H H H H H (1) 2Y1 H H L H H H H H H (2) 2Y2 H H H L H H H H H Outputs (3) 2Y3 H H H H L H H H H (4) 1Y0 H H H H H L H H H (5) 1Y1 H H H H H H L H H (6) 1Y2 H H H H H H H L H (7) 1Y3 H H H H H H H H L

2-Line-to-4-LineDecoder or 1-Line-to-4-Line Demultiplexer Inputs Select B X L L H H X A X L H L H X Strobe G1 H L L L L X Data C1 X H H H H L 1Y0 H L H H H H Outputs 1Y1 H H L H H H 1Y2 H H H L H H 1Y3 H H H H L H Select B X L L H H X A X L H L H X Inputs Strobe G2 H L L L L X Data C2 X L L L L H 2Y0 H L H H H H Outputs 2Y1 H H L H H H 2Y2 H H H L H H 2Y3 H H H H L H

H = HIGH level L = LOW level X = don’tcare Note 1: C = inputs C1 and C2 connected together Note 2: G = inputs G1 and G2 connected together

Logic Diagram

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DM74LS155 • DM74LS156

Absolute Maximum Ratings(Note 3)
Supply Voltage Input Voltage Operating Free Air Temperature Range Storage Temperature Range 7V 7V 0°C to +70°C −65°C to +150°C
Note 3: The “Absolute Maximum Ratings” are those values beyondwhich the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation.

DM74LS155 Recommended Operating Conditions
Symbol VCC VIH VIL VOH IOLTA Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current Free Air Operating Temperature 0 Parameter Min 4.75 2 0.8 −0.4 8 70 Nom 5 Max 5.25 Units V V V mA mA °C

DM74LS155 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted) Symbol VI VOH VOL Parameter Input Clamp Voltage HIGH...