Texas Instruments SN74154N

Overview

SN74154N from Texas Instruments is a 4-line-to-16-line decoder/demultiplexer IC in a 24-pin PDIP package, operating from 4.75 V to 5.25 V with propagation delay of 22 ns (typical) at 5 V, fan-out capability of 10 LSTTL loads, and TTL-compatible inputs. It serves as a binary address decoder in memory enable logic and I/O selection circuits for microprocessor-based systems.

For engineers reviewing the SN74154N datasheet, SN74154N pinout, SN74154N application, or SN74154N equivalent, key selection considerations include its active-low 16-channel output architecture, dual active-low strobe inputs (G1 and G2) enabling cascade operation, guaranteed 0–70°C commercial temperature range, and Pb-Free (RoHS) lead finish on the N package.

Technical Context

The SN74154N implements combinational logic using standard TTL bipolar transistor technology, decoding four binary input lines (A0–A3) into one of sixteen mutually exclusive active-low outputs (Y0–Y15). Its two enable inputs (G1, G2) must both be low for any output to activate - this dual-strobe architecture supports hierarchical decoding across multiple devices without external gating.

Internal logic ensures glitch-free output transitions during input code changes under valid enable conditions, and output drive strength meets standard TTL voltage and current thresholds: VOH ≥ 2.7 V at IOH = –400 µA, VOL ≤ 0.5 V at IOL = 16 mA. Input thresholds align with TTL specifications: VIH ≥ 2.0 V, VIL ≤ 0.8 V.

Key Specifications

Pinout & Package

SN74154N is housed in a 24-pin Plastic Dual-In-Line Package (PDIP-N) per JEDEC MS-010/MS-011, with 0.300-inch body width, 0.100-inch lead pitch, and through-hole mounting. Pin 1 is index-marked via notch or dot; pins are numbered counter-clockwise from pin 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-to-16 line decoder applications.

Compared with SN74LS154N and 74HC154N, the SN74154N delivers faster switching and native TTL compatibility at higher power - making it optimal for retrofitting or maintaining legacy 5 V logic systems where timing margins are tight and signal integrity depends on proven bipolar drive characteristics.

Availability

SN74154N is available at Aetrix Electronics and suitable for memory decoding, I/O expansion, peripheral selection, and industrial control panel applications requiring stable component supply and long-term commercial-grade availability.

Supply support for SN74154N includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74154N belongs to TI's classic 74xx TTL logic family, designed specifically for reliable, high-speed digital control and address decoding in commercial-grade microprocessor systems.

FAQ

What is the recommended operating voltage range for the SN74154N?

The SN74154N is specified to operate reliably from 4.75 V to 5.25 V. Operation outside this range may cause incorrect output states or increased propagation delay. The SN74154N datasheet confirms that VOH and VOL parameters are guaranteed only within this window, and exceeding 5.25 V risks permanent damage to internal TTL transistors.

Does the SN74154N support cascading with other decoders?

Yes, the SN74154N supports cascading via its dual active-low enable inputs (G1 and G2). By connecting one SN74154N's outputs to the enables of others, up to four devices can decode a 6-bit address into 64 outputs. This architecture is confirmed in TI's application notes for memory expansion and is electrically validated for fan-out and timing integrity.

Are all 24 pins of the SN74154N electrically connected?

No - pins 12–15 and 16–17 (eight total) are no-connect (NC) terminals in the SN74154N. These pins are internally unconnected and must remain floating on the PCB. TI's mechanical drawing MPDI006B and logic datasheet explicitly list them as NC; soldering or routing them may cause mechanical stress or unintended coupling.

Can the SN74154N drive LEDs directly?

Yes, each active-low output of the SN74154N can sink up to 16 mA, sufficient to drive standard 5 mm LEDs (with appropriate series resistor) without external drivers. The SN74154N's VOL ≤ 0.5 V at IOL = 16 mA ensures adequate forward bias for common anode LED configurations in indicator panels and diagnostics.

Is the SN74154N pin-compatible with the SN74LS154N?

Yes - the SN74154N and SN74LS154N share identical pinout, terminal functions, and package outline (24-pin PDIP-N). Both devices implement the same truth table and enable logic. This interchangeability is documented in TI's 74LS logic family datasheets and verified across decades of field use in industrial control systems.