Texas Instruments SN74CBT3251DBQRG4

Overview

SN74CBT3251DBQRG4 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 signals to a common A port under 3-bit binary address (S0–S2) and active-low OE control-used in microcontroller GPIO expansion and keypad scanning systems.

For engineers reviewing the SN74CBT3251DBQRG4 datasheet, SN74CBT3251DBQRG4 pinout, SN74CBT3251DBQRG4 application, or SN74CBT3251DBQRG4 equivalent, key selection criteria include its low Ron for minimal signal attenuation, sub-nanosecond switching speed, SSOP-16 package compatibility with high-density layouts, and guaranteed operation over industrial temperature range without level-shifting.

Technical Context

The SN74CBT3251DBQRG4 implements an analog-capable, bidirectional CMOS FET switch matrix with integrated 3-to-8 binary decoder logic. Its channel selection is fully static: S0–S2 directly determine which B_n terminal connects to A, while OE independently enables or isolates all paths. No internal latching or clocking is involved-operation is purely combinational and voltage-transparent.

All eight B ports and the A port support 0 V to 5 V analog/digital signal levels with rail-to-rail pass-through capability. The device draws only 3 µA quiescent current and exhibits 3.5 pF control-input capacitance, enabling fast edge-driven switching without excessive drive burden on MCU GPIOs.

Key Specifications

Pinout & Package

SN74CBT3251DBQRG4 uses a 16-pin Shrink Small-Outline Package (SSOP-16) with 0.65 mm lead pitch, 3.90 mm × 4.90 mm body size, and 1.75 mm maximum height-designed for automated assembly and thermal performance in space-constrained PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FET multiplexer applications.

Compared with SN74CBT3244DBQR and 74LVC1G3157DCUR, the SN74CBT3251DBQRG4 uniquely integrates 3-bit decoding, single-A-port architecture, and industrial-temp-rated 5 Ω Ron in one SSOP-16 package-making it optimal for space-constrained, software-controlled multiplexing where pin count and layout simplicity are critical.

Availability

SN74CBT3251DBQRG4 is available at Aetrix Electronics and suitable for industrial control systems, consumer electronics manufacturing, and embedded test equipment requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for SN74CBT3251DBQRG4 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 50 years of innovation in high-reliability logic and interface solutions.

The SN74CBT3251DBQRG4 belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered specifically for low-latency, low-distortion signal routing in industrial, computing, and communications infrastructure where deterministic timing and analog fidelity are essential.

FAQ

What is the maximum continuous current rating per channel for the SN74CBT3251DBQRG4?

The SN74CBT3251DBQRG4 supports up to 128 mA continuous channel current per switched path, as specified in Absolute Maximum Ratings. This allows reliable operation with typical digital logic loads and moderate analog signals-provided total V_CC/GND current remains within limits and thermal design accommodates power dissipation at worst-case r_ON and load conditions.

Does the SN74CBT3251DBQRG4 require external pull-up or pull-down resistors on its control inputs?

No, the SN74CBT3251DBQRG4 does not require external pull-up or pull-down resistors on S0, S1, S2, or OE because its TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) are designed for direct connection to standard 5 V logic outputs. However, unused control inputs must be tied to V_CC or GND to prevent floating states that could cause undefined switching behavior.

Can the SN74CBT3251DBQRG4 be used to route analog sensor signals such as from a thermistor or potentiometer?

Yes, the SN74CBT3251DBQRG4 supports rail-to-rail analog signals from 0 V to 5 V on all ports, making it suitable for routing thermistor voltage dividers, potentiometer wiper outputs, or other low-bandwidth analog sources. Its 5 Ω r_ON introduces negligible error (<0.1%) for source impedances below 500 Ω, and its low crosstalk preserves signal integrity in multi-sensor configurations.

What is the meaning of the "G4" suffix in SN74CBT3251DBQRG4?

The "G4" suffix in SN74CBT3251DBQRG4 indicates Texas Instruments' green packaging standard: lead-free (Pb-free), RoHS-compliant construction with NiPdAu lead finish and halogen-free molding compound. It confirms compliance with environmental regulations without affecting electrical or thermal specifications of the base SN74CBT3251DBQR part.

How does the SN74CBT3251DBQRG4 behave when OE is held high?

When OE is held high, the SN74CBT3251DBQRG4 places all eight B ports and the A port into high-impedance isolation-effectively disconnecting all internal FET switches regardless of S0–S2 state. This provides true signal blocking with >60 dB off-isolation at 10 MHz, enabling safe sharing of the A port among multiple SN74CBT3251DBQRG4 devices on a common bus.