Texas Instruments SN74F157ADR

Overview

SN74F157ADR from Texas Instruments is a quad 2-input data selector/multiplexer with common strobe (G) control, operating at 4.5–5.5 V supply, delivering true logic outputs, 6.5 ns max tPHL (A/B→Y), and 11 ns max tPLH (G→Y) at 5 V/25°C. It routes one of two 4-bit input sources to four outputs in TTL-compatible digital systems such as address/data bus switching in legacy microprocessor peripherals.

For engineers reviewing the SN74F157ADR datasheet, SN74F157ADR pinout, SN74F157ADR application, or SN74F157ADR equivalent, key selection criteria include strobe-controlled 4-bit multiplexing capability, SOIC-16 package compatibility, guaranteed 0°C to 70°C operation, TTL-level input thresholds (VIL ≤ 0.8 V, VIH ≥ 2 V), and output drive strength (IOL = 20 mA, IOH = −1 mA).

Technical Context

The SN74F157ADR implements four independent 2:1 multiplexers sharing a single active-low enable (G) input and a common select line (A/B). When G is high, all Y outputs are forced low regardless of A/B or data inputs; when G is low, the A/B signal selects whether inputs A1–A4 or B1–B4 appear at outputs Y1–Y4.

It uses standard bipolar TTL circuitry with buffered inputs and outputs, supporting fan-out of 10 LS-TTL loads. Its propagation delays are asymmetric: tPHL (A/B→Y) is faster (≤7 ns) than tPLH (≤11 ns), reflecting inherent transistor turn-on/off timing differences in the F-series process.

Key Specifications

Pinout & Package

SN74F157ADR is supplied in a 16-pin SOIC (D) package per TI's packaging addendum, with 7.5 mm body width, 1.75 mm height max, and 1.27 mm lead pitch. Pin 1 is located in quadrant Q1 per tape-and-reel orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.

Compared with SN74F157ADR, SN74LS157N trades speed for reduced power, while SN74HC157DR shifts to CMOS operation with broader supply flexibility but different noise margin and loading behavior-neither is pin-compatible without timing or interface validation.

Availability

SN74F157ADR is available at Aetrix Electronics and suitable for microprocessor bus switching, legacy memory expansion, parallel data routing, and digital test equipment requiring stable component supply across long-lifecycle industrial deployments.

Supply support for SN74F157ADR 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 SN74F157ADR belongs to TI's 74F fast TTL logic family, designed for high-speed digital control in computing, instrumentation, and communications equipment where propagation delay and fan-out were critical constraints.

FAQ

What is the maximum clock frequency supported by SN74F157ADR?

The SN74F157ADR does not operate on a clock signal-it is combinatorial logic with propagation delays specified up to 11 ns (tPLH, G→Y). In practice, it supports data rates up to ~90 MHz for clean, well-terminated 4-bit bus switching when used with appropriate setup/hold margins relative to controlling logic.

Is SN74F157ADR compatible with 3.3 V logic systems?

No, SN74F157ADR is not 3.3 V compatible. Its absolute maximum VCC is 7 V, but recommended operation is strictly 4.5–5.5 V. Input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and output levels (VOH ≥ 2.5 V at IOH = −1 mA) assume a 5 V supply; interfacing with 3.3 V systems requires level translation.

Does SN74F157ADR have internal pull-up or pull-down resistors on its inputs?

No, SN74F157ADR has no internal pull-up or pull-down resistors. All inputs-A/B, G, and data lines-must be actively driven to valid TTL logic levels; floating inputs may cause unpredictable output states or increased power consumption due to input stage bias instability.

Can SN74F157ADR drive LEDs directly?

Yes, SN74F157ADR can drive LEDs directly in active-low configuration: connect LED anode to VCC and cathode to Y output through a current-limiting resistor. With IOL = 20 mA, it supports up to ~15 mA LED current (using 220 Ω at 5 V), sufficient for indicator use but not high-brightness arrays.

What is the meaning of "F157A" marking on SN74F157ADR devices?

The "F157A" marking on SN74F157ADR refers to the functional identifier per TI's standard part numbering: "F" denotes the 74F fast TTL family, "157" is the base device number for quad 2-input multiplexers, and "A" indicates the improved version with tighter AC/DC specifications versus original '157 design-this marking appears on the top surface of the SOIC package.