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Texas Instruments SN74LS42N — Logic ICs

Texas Instruments SN74LS42N Decoder/Demultiplexer, 1x4:10

MPNSN74LS42N
End of Life

Texas Instruments 74LS series Decoder/Demultiplexer, SN74LS42N, 1 x 4:10 circuit, Through Hole, 16-DIP (0.300", 7.62mm), 4.75V ~ 5.25V supply, 0°C ~ 70°C.

$3.03Ref. price · indicative, final on quote
Texas Instruments SN74LS42N datasheet (PDF)
Packaging16-DIP (0.300", 7.62mm)
RoHSROHS3 Compliant
Series74LS
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

SN74LS42N specifications
ParameterValue
TypeDecoder/Demultiplexer
Series74LS
MountingThrough Hole
Supply voltage4.75V ~ 5.25V
Voltage supply sourceSingle Supply
Current - output high, low400µA, 8mA
Operating temperature0°C ~ 70°C
Circuit1 x 4:10
PackageTube
Case16-DIP (0.300\", 7.62mm)
Independent circuits1

Product details

The Texas Instruments SN74LS42N is a 1-of-10 BCD-to-decimal decoder/demultiplexer from the 74LS Schottky TTL family. It takes a 4-bit BCD input and asserts one of ten active-low outputs, making it the standard part for driving numeric displays, selecting memory banks, or routing control signals in 5V logic systems. The 16-pin DIP package suits through-hole assembly and rework-friendly boards. The 4.75V to 5.25V supply range means this part expects a regulated 5V rail — not a loosely-tolerated bus.

Output drive and loading

Output high current is 400µA, output low sinks 8mA — standard LS TTL drive levels. Each output can drive one or two standard 74LS inputs directly, but fan-out beyond that needs a buffer. If your design routes this decoder to a bus with multiple loads, budget a 74LS244 or similar line driver on the outputs.

Lifecycle and supply reality

For a legacy 74LS BOM line, this is a stable fit.

Frequently asked questions

What is the function of the SN74LS42N?

The SN74LS42N is a 1-of-10 BCD-to-decimal decoder/demultiplexer. It accepts a 4-bit BCD input (0000 through 1001) and asserts the corresponding output line low — output 0 for input 0000, output 1 for 0001, and so on up to output 9. Inputs above 1001 (1010–1111) produce no asserted output; all outputs remain high. This makes it the standard decoder for 7-segment displays, memory chip selects, or any application needing to map a 4-bit code to one of ten control lines.

Can SN74LS42N be used as a demultiplexer in a 74LS logic design?

Yes. The SN74LS42N functions as a 1-line-to-10-line demultiplexer when the data input is applied to the A input (LSB) and the strobe or address lines are driven from the other three inputs. The active-low outputs route the inverted data to the selected line. It works directly with other 74LS family parts on a shared 5V rail, though the 400µA/8mA drive limits fan-out to one or two standard LS loads per output.