Texas Instruments SN74CBT3251DE4

Overview

SN74CBT3251DE4 from Texas Instruments is a 1-of-8 FET multiplexer/demultiplexer with TTL-compatible control inputs, 5-Ω typical on-state resistance at 5 V, <0.24 ns propagation delay, and operation across –40°C to 85°C. It routes one of eight bidirectional B-port channels to a common A port under S0–S2 binary selection and active-low OE enable-used in keypad polling, GPIO expansion, and signal gating in industrial microcontroller systems.

For engineers reviewing the SN74CBT3251DE4 datasheet, SN74CBT3251DE4 pinout, SN74CBT3251DE4 application, or SN74CBT3251DE4 equivalent, this page delivers verified electrical specs, package mapping to SOIC-16 (D package), functional mode table alignment, real-world use cases, and two validated alternative parts for design flexibility and supply continuity.

Technical Context

The SN74CBT3251DE4 implements an 8-channel analog/digital switch matrix using NMOS pass-gate FETs, enabling bidirectional signal flow between A and any selected Bn port. Its internal binary decoder interprets S0–S2 as a 3-bit address to activate exactly one channel when OE is low; all channels disconnect when OE is high.

It operates within 4 V to 5.5 V supply range, supports TTL-level control inputs (VIH ≥ 2 V, VIL ≤ 0.8 V), and maintains low crosstalk (< –60 dB) and minimal charge injection (< 10 pC), making it suitable for low-noise data routing in mixed-signal environments without level-shifting.

Key Specifications

Pinout & Package

SN74CBT3251DE4 is packaged in a 16-pin SOIC (D package), 3.91 mm × 9.90 mm body size, with 1.27 mm lead pitch and gull-wing leads. Pin 1 is marked by a beveled corner or notch; pin 6 is NC (no internal connection); pin 8 is GND; pin 16 is VCC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 1-of-8 FET multiplexer applications.

Compared with SN74CBT3251DE4, SN74CBTD3384DBQR offers expanded channel count and dual-voltage flexibility but trades off pin compatibility and adds complexity; 74LVC1G3157DP delivers superior on-resistance and footprint reduction but cannot replace 8-channel routing-selection depends strictly on topology and voltage architecture requirements.

Availability

SN74CBT3251DE4 is available at Aetrix Electronics and suitable for industrial automation interfaces, microcontroller peripheral expansion, and digital radio signal routing requiring stable component supply and long-term production support.

Supply support for SN74CBT3251DE4 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 specializing in analog, embedded processing, and connectivity technologies, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74CBT3251DE4 belongs to TI's CBT (Crosspoint Bus Switch) family, designed specifically for low-latency, bidirectional signal routing in high-speed digital systems where minimal propagation delay and low on-resistance are critical.

FAQ

What is the maximum continuous current rating for SN74CBT3251DE4?

The SN74CBT3251DE4 supports up to 128 mA continuous channel current per switched path, as specified in its Absolute Maximum Ratings table. This value applies under recommended operating conditions (VCC = 4–5.5 V, TA = –40°C to 85°C) and must not be exceeded to avoid thermal damage or reliability degradation. The device also limits total supply current (ICC) to 3 µA typical, ensuring low static power draw.

Does SN74CBT3251DE4 support analog signal switching?

Yes, SN74CBT3251DE4 supports analog signals from 0 V to 5 V due to its FET-based pass-gate architecture and rail-to-rail conduction capability. Its 5-Ω typical on-resistance and low charge injection (<10 pC) preserve analog waveform fidelity, making it suitable for routing sensor outputs, audio signals, or reference voltages-provided signal slew rates remain within the device's bandwidth limits.

How does the OE pin function in SN74CBT3251DE4?

The OE (Output Enable) pin on SN74CBT3251DE4 is an active-low control that globally enables or disables all eight switch channels. When OE is low, the selected Bn port connects bidirectionally to the A port per S0–S2 address; when OE is high, all channels are open-circuited, isolating A from B1–B8. This provides hardware-level signal gating independent of address lines.

Is SN74CBT3251DE4 pin-compatible with other CBT-series multiplexers?

No, SN74CBT3251DE4 is not pin-compatible with other CBT multiplexers such as SN74CBT3383 or SN74CBT3305 due to differing pin counts, signal assignments (e.g., presence of NC pin), and internal topology. Its 16-pin SOIC layout with dedicated S0–S2, OE, A, and B1–B8 mapping is unique to the 1-of-8 configuration. Board redesign is required for substitution.

What thermal considerations apply to SN74CBT3251DE4 in continuous operation?

SN74CBT3251DE4 has a junction-to-ambient thermal resistance (RθJA) of 73°C/W in SOIC-16 package. At maximum 128 mA channel current and 5 Ω Ron, worst-case power dissipation is ~82 mW per active channel. With proper PCB copper pour and a 0.1-μF bypass capacitor near VCC, junction temperature remains within safe limits (<125°C) even at 85°C ambient-no heatsink required for typical usage.