Texas Instruments SN74HC253DT

Overview

SN74HC253DT from Texas Instruments is a dual 4-line to 1-line data selector/multiplexer with 3-state outputs, operating across 2 V to 6 V. It features two independent multiplexers, full binary decoding (A/B select lines), strobe-controlled output enables (OE), and ±6-mA drive capability at 5 V. Used in bus-organized digital systems for parallel-to-serial conversion and signal routing.

For engineers reviewing the SN74HC253DT datasheet, SN74HC253DT pinout, SN74HC253DT application, or SN74HC253DT equivalent, this page delivers verified functional modes, switching timing (tpd = 32 ns @ 6 V, CL = 50 pF), 3-state output behavior, supply voltage flexibility, and real-world bus interface design considerations.

Technical Context

The SN74HC253DT implements two independent CMOS-based 4:1 multiplexers sharing common select inputs (A, B) but with separate 3-state output-enable (OE) controls per section. Each section decodes A/B to route one of four data inputs (C0–C3) to its Y output.

Its 3-state outputs support bidirectional bus interfacing: when OE is high, Y enters high-impedance state; when OE is low, Y drives logic-high or logic-low with ±6 mA sink/source capability at 5 V and typical propagation delay of 32 ns under 50-pF load.

Key Specifications

Pinout & Package

SN74HC253DT is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm with standard 1.27-mm pitch. Pin numbering follows JEDEC MS-012, with Pin 1 located at the top-left corner marked by a beveled edge or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC153DR and 74LVC253PW, the SN74HC253DT uniquely balances 3-state bus compatibility, wide supply range, and proven industrial temperature operation (−40°C to 85°C) without requiring layout changes or voltage translation.

Availability

SN74HC253DT is available at Aetrix Electronics and suitable for industrial control systems, automated test equipment, embedded data acquisition, and legacy bus interface designs requiring stable component supply and long-term sourcing continuity.

Supply support for SN74HC253DT 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The SN74HC253DT belongs to TI's 74HC logic family, designed for high-noise-immunity, low-power, pin-compatible upgrades to legacy TTL multiplexers in cost-sensitive and reliability-critical applications.

FAQ

What is the maximum operating frequency supported by the SN74HC253DT?

The SN74HC253DT does not specify a maximum clock frequency in its datasheet because it is asynchronous logic. Its usable data rate depends on propagation delay (tpd ≤ 32 ns @ 6 V, CL = 50 pF) and enable timing (ten ≤ 21 ns). For reliable operation with clean edges, designers typically limit input transition rates to ≤10 MHz in bus-sharing configurations. The SN74HC253DT remains functional up to 25 MHz in point-to-point routing with proper termination and layout.

Can the SN74HC253DT operate at 3.3 V and interface directly with a 3.3-V microcontroller?

Yes, the SN74HC253DT operates across 2 V to 6 V, making 3.3 V well within its recommended range. Its VIH (≥2.31 V @ VCC = 3.3 V) and VIL (≤0.99 V) thresholds are compatible with standard 3.3-V CMOS logic levels. Outputs swing rail-to-rail, ensuring full logic-high/low margins. The SN74HC253DT requires no level-shifting circuitry when paired with 3.3-V MCUs.

Is the SN74HC253DT pin-compatible with the SN74HC153?

No, the SN74HC253DT is not pin-compatible with the SN74HC153. While both are dual 4:1 multiplexers, the SN74HC153 uses active-high outputs and shares a single OE, whereas the SN74HC253DT provides two independent active-low OE pins and 3-state outputs. Pin assignments differ significantly - for example, SN74HC153 dedicates Pins 1 and 15 to GND/VCC, while SN74HC253DT uses those pins for Y1/Y2 outputs. The SN74HC253DT requires distinct PCB layout.

What is the purpose of the two separate OE pins on the SN74HC253DT?

The two independent OE pins (OE1 on Pin 2, OE2 on Pin 14) allow selective 3-state control of each multiplexer section. This enables time-multiplexed bus sharing - e.g., enabling Y1 while disabling Y2 to avoid contention - or independent gating of two data paths in safety-critical systems. Unlike single-OE devices, the SN74HC253DT supports fault-isolated operation where one section remains active during diagnostics on the other. This architecture is integral to the SN74HC253DT's design.

Does the SN74HC253DT require external pull-up resistors on its outputs?

No, the SN74HC253DT does not require external pull-up resistors on its outputs when used in 3-state bus applications. Its outputs actively drive both logic high and low when enabled (OE low), eliminating need for passive pull-ups. Pull-ups are only necessary if the application demands a defined logic state during high-impedance periods - but that contradicts standard bus arbitration practice. The SN74HC253DT's design assumes controlled OE sequencing, not passive termination.