Texas Instruments SN74ALS151N

Overview

SN74ALS151N from Texas Instruments is an 8-line to 1-line TTL-compatible data selector/multiplexer in a 16-pin plastic DIP (PDIP) package, operating from 0°C to 70°C with 5 V supply, 24 mA low-level output drive, and propagation delays as low as 3 ns (t_PLH, D→Y). It functions as a Boolean function generator or parallel-to-serial converter in digital logic systems.

For engineers reviewing the SN74ALS151N datasheet, SN74ALS151N pinout, SN74ALS151N application, or SN74ALS151N equivalent, key selection criteria include its dual complementary outputs (Y and W), active-low strobe enable (G), binary-select inputs (A/B/C), and compatibility with legacy 74ALS logic families in industrial control and test equipment design.

Technical Context

The SN74ALS151N implements full binary decoding across three select lines (A, B, C) to route one of eight data inputs (D0–D7) to the true output (Y) while simultaneously driving the inverted output (W). Its strobe input (G) must be low to enable selection; a high G forces Y low and W high - enabling use as an active-low enable-controlled data gate.

It uses bipolar ALS (Advanced Low-power Schottky) technology, delivering 24 mA sink current at 0.4 V output voltage and 2.4 V minimum VOH at −2.6 mA source, with typical propagation delays of 10 ns (D→Y) and 15 ns (A/B/C→Y) under 50 pF load conditions. Input clamping diodes simplify system-level ESD protection and bus interfacing.

Key Specifications

Pinout & Package

SN74ALS151N is housed in a 16-pin plastic dual in-line package (PDIP-N) with 300-mil body width and 0.1-inch lead pitch. Pin 1 is located at the top-left corner when viewed from the top with notch or dot orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8:1 multiplexer applications.

Compared with SN74LS151N, SN74ALS151N delivers 3× higher output drive and 40% lower power at equal speed; compared with SN74AS151N, it trades 2× speed for 2.5× lower ICC and better noise margin - making it optimal for balanced commercial-grade digital systems.

Availability

SN74ALS151N is available at Aetrix Electronics and suitable for industrial control logic, test equipment signal routing, legacy system repair, and Boolean function generation requiring stable component supply and long-term obsolescence management.

Supply support for SN74ALS151N 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial and automotive qualification.

The SN74ALS151N belongs to TI's legacy 74ALS logic family, designed specifically for high-reliability commercial applications requiring robust noise immunity, predictable timing, and backward compatibility with earlier TTL generations.

FAQ

What is the maximum clock frequency supported by SN74ALS151N in a data selection application?

The SN74ALS151N does not operate on a clock signal - it is asynchronous. Its usable data rate depends on propagation delay and setup/hold timing. With worst-case t_PHL/t_PLH of 24 ns (D→Y) and 19 ns (G→Y), it supports reliable operation up to approximately 33 MHz in systems where selection signals are stable before data transitions. The SN74ALS151N datasheet specifies no clock; timing is purely combinational.

Can SN74ALS151N interface directly with 3.3 V logic inputs?

SN74ALS151N inputs are TTL-compatible with V_IH = 2.0 V min and V_IL = 0.8 V max, so 3.3 V CMOS outputs (typically 2.4–3.3 V high) meet VIH requirements. However, 3.3 V logic may not reliably drive SN74ALS151N inputs low due to V_IL margin constraints; a pull-down resistor or level shifter is recommended for guaranteed low-level recognition. The SN74ALS151N itself operates only at 5 V.

Does SN74ALS151N have 3-state outputs?

No, SN74ALS151N has push-pull (totem-pole) outputs with complementary Y and W terminals - neither is high-impedance or 3-state. The strobe (G) input disables data routing by forcing Y = low and W = high, but outputs remain actively driven. For bus-sharing applications requiring true high-Z states, consider SN74ALS151A variants or dedicated 3-state multiplexers like SN74ALS251N.

What is the purpose of the W output on SN74ALS151N?

The W output on SN74ALS151N provides the logical complement of the Y output - when Y = HIGH, W = LOW, and vice versa - with matched propagation delay (≤3 ns skew). This eliminates the need for an external inverter in applications requiring both polarities, such as differential signaling, XOR implementation, or active-low enable paths. The SN74ALS151N W output is not a separate function but a hardware-generated inverse of Y.

Is SN74ALS151N RoHS compliant?

Yes, SN74ALS151N is RoHS compliant per TI's packaging documentation: it features NiPdAu (NIPDAU) lead finish, meets JEDEC J-STD-020 moisture sensitivity Level-1 (unlimited floor life), and carries "Yes" in the RoHS column for all active N-package variants including SN74ALS151N and SN74ALS151N.A. Lead-free assembly is supported with peak reflow at 260°C.