Texas Instruments SN74F253NSR

Overview

SN74F253NSR from Texas Instruments is a dual 4-line to 1-line data selector/multiplexer with independent 3-state outputs, designed for bus-organized digital systems. It features two independent 4:1 multiplexer sections (1Y and 2Y), common select inputs (A/B), separate strobe controls (1G/2G), operates at 4.5–5.5 V, and is rated for 0°C to 70°C ambient temperature - used in parallel-to-serial conversion and data routing in TTL-based control logic.

For engineers reviewing the SN74F253NSR datasheet, SN74F253NSR pinout, SN74F253NSR application, or SN74F253NSR equivalent, key selection criteria include its dual-section 3-state output architecture, propagation delays under 13 ns (tPLH/tPHL), guaranteed 24 mA low-level drive capability, and compatibility with standard 16-pin PDIP packaging for legacy board integration and test fixtures.

Technical Context

The SN74F253NSR implements two independent 4:1 multiplexers sharing select lines A and B, each with dedicated active-low strobe (1G, 2G) enabling high-impedance output control. Its internal logic uses F-type TTL circuitry with bipolar transistor implementation, delivering fast switching via optimized gate propagation paths and Schottky-clamped outputs.

Each section decodes A/B inputs to route one of four data inputs (C0–C3) to its respective output (1Y or 2Y), while strobe assertion disables the output to Z-state. The device supports bus driving by allowing only one output to be enabled at a time, minimizing contention on shared data lines in backplane or motherboard interconnects.

Key Specifications

Pinout & Package

SN74F253NSR is supplied in a 16-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and through-hole mounting. Pin pitch is 0.1 inch; lead finish is NiPdAu (RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual 4:1 multiplexer applications.

Compared with SN74F253NSR, SN74LS253N trades speed for noise immunity and lower power, while SN74HC253N offers supply flexibility at the cost of TTL bus compatibility - selection depends on whether legacy bus drive strength or modern voltage scalability is prioritized.

Availability

SN74F253NSR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy test equipment signal routing, and microcontroller address decoding requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74F253NSR 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 solutions for industrial, automotive, and communications markets.

The SN74F series delivers high-speed TTL logic with Schottky clamping for legacy system upgrades and repair - engineered for drop-in replacement in 1980s–1990s digital control hardware.

FAQ

What is the maximum clock frequency supported by SN74F253NSR in multiplexer mode?

The SN74F253NSR does not operate on a clock signal - it is a combinational logic device. Its usable data rate is determined by propagation delay: with tPLH ≤13 ns and tPHL ≤10 ns, it reliably supports input changes at up to ~40 MHz in synchronous bus applications when paired with appropriate setup/hold timing. This performance is validated across 0°C to 70°C and 4.5–5.5 V.

Does SN74F253NSR support hot insertion or live bus swapping?

No, SN74F253NSR is not designed for hot insertion. Its absolute maximum ratings specify that output voltages must remain within −0.5 V to 5.5 V during power-off or disabled states, and no current-limiting or ESD-hardened protection is built in for live-connect scenarios. For hot-swap applications, external protection circuitry or purpose-built hot-swap ICs are required alongside SN74F253NSR.

Can SN74F253NSR be used with 3.3 V logic systems?

SN74F253NSR is not 3.3 V compatible. Its recommended VCC is 4.5–5.5 V, and input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) assume 5 V TTL signaling. Driving its inputs from 3.3 V logic may result in marginal or non-functional VIH margins. For 3.3 V systems, consider SN74LVC253 or level-shifting buffers instead of direct use of SN74F253NSR.

What is the function of the NC pins on SN74F253NSR?

SN74F253NSR has no NC (No Connect) pins in its PDIP-N package. All 16 pins are assigned: pins 1–8 and 9–16 correspond to 1G, B, 1C3, 1C2, 1C1, 1C0, 1Y, GND, VCC, 2G, A, 2C3, 2C2, 2C1, 2C0, 2Y respectively. NC pins appear only in ceramic chip carrier (FK) variants - not applicable to SN74F253NSR's PDIP configuration.

How does SN74F253NSR differ from SN74F153 in functional capability?

SN74F253NSR is the 3-state output version of SN74F153. While both contain dual 4:1 multiplexers with shared A/B selects, SN74F253NSR adds individual output-enable (1G/2G) inputs to place each Y output in high-impedance state - enabling direct bus connection without external tri-state buffers. SN74F153 lacks this feature and provides only active-high outputs, limiting its use in shared-bus architectures.