Texas Instruments SN74CBT3251PWR

Overview

SN74CBT3251PWR from Texas Instruments is a 1-of-8 FET multiplexer/demultiplexer in TSSOP-16 package, featuring 5-Ω typical on-state resistance at 5 V, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and operation across –40°C to 85°C. It routes one of eight bidirectional B-port channels to a common A port under 3-bit binary address (S0–S2) and active-low OE control - used for GPIO expansion and keypad scanning in microcontroller systems.

For engineers reviewing the SN74CBT3251PWR datasheet, SN74CBT3251PWR pinout, SN74CBT3251PWR application, or SN74CBT3251PWR equivalent, key selection criteria include its low Ron (5 Ω typ), sub-1 ns propagation delay (tpd = 0.24 ns @ 5 V), 50 pF load switching capability, and compatibility with 4–5.5 V supply rails in space-constrained TSSOP layouts.

Technical Context

The SN74CBT3251PWR implements an analog-capable, bidirectional CMOS FET switch matrix with integrated 3-to-8 binary decoder logic. Its channel selection is determined solely by S0/S1/S2 states when OE is low, enabling direct connection between A and one selected Bn port without level translation or direction control.

All eight B ports and the A port support 0–5 V analog/digital signal routing; input clamp current is ±18 mA, absolute max VCC is 7 V, and ESD rating meets ±1500 V HBM. The device draws only 3 µA ICC at 5.5 V and exhibits <10 pF off-state capacitance per port - critical for high-speed bus isolation and low-crosstalk signal gating.

Key Specifications

Pinout & Package

TSSOP-16 package (4.40 mm × 5.00 mm, 1.2 mm max height), lead finish NIPDAU, moisture sensitivity level 1 (260°C peak reflow, unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3251PWR, SN74CBT3244PWR offers higher channel concurrency but no built-in addressing, while 74LVC1G3157DP delivers lower footprint at the cost of scalability - SN74CBT3251PWR uniquely balances integration, speed, and analog performance in a single 16-pin TSSOP.

Availability

SN74CBT3251PWR is available at Aetrix Electronics and suitable for industrial automation, consumer appliance control, and programmable logic circuit design requiring stable component supply and long-term manufacturability.

Supply support for SN74CBT3251PWR 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-performance logic and interface solutions.

The SN74CBT3251PWR belongs to TI's CBT (Crossbar Bus Transceiver) family - designed specifically for low-latency, low-distortion signal routing in mixed-signal systems where timing precision and analog fidelity are critical.

FAQ

What is the maximum continuous current rating for SN74CBT3251PWR?

The SN74CBT3251PWR supports a continuous channel current of 128 mA per switched path, as specified in Absolute Maximum Ratings. This allows reliable operation with typical digital I/O loads and moderate analog sensor drive requirements without thermal derating at ambient temperatures up to 85°C. Exceeding this limit risks junction overheating and permanent device failure.

Does SN74CBT3251PWR support bidirectional signal flow?

Yes, SN74CBT3251PWR supports true bidirectional analog/digital signal routing between the A port and any selected Bn port. Its FET-based architecture imposes no inherent directionality - data can flow from A to Bn (multiplexer mode) or from Bn to A (demultiplexer mode) with identical electrical characteristics, including 5 Ω Ron and sub-nanosecond tpd in both directions.

Can SN74CBT3251PWR operate with a 3.3 V supply?

No, SN74CBT3251PWR requires a minimum supply voltage of 4 V per Recommended Operating Conditions. At 3.3 V, the internal FETs fail to fully enhance, resulting in elevated Ron (>20 Ω), increased propagation delay, and potential logic threshold violations. For 3.3 V systems, consider TI's SN74LVC1G3157 or similar LVC-family switches.

What is the purpose of the NC pin (Pin 6) on SN74CBT3251PWR?

Pin 6 is a no-connect (NC) terminal with no internal bonding or circuit connection. It must be left unconnected on the PCB - neither tied to VCC nor GND. While it may serve mechanical or package alignment purposes, routing traces to or placing vias on Pin 6 violates TI's layout recommendations and risks unintended coupling or solder bridging in fine-pitch TSSOP assembly.

How does the OE pin affect switching behavior in SN74CBT3251PWR?

When OE is high (VCC), all internal switches open simultaneously, placing the A port and all B ports in high-impedance state regardless of S0–S2 values - effectively disconnecting all paths. When OE is low (≤0.8 V), the selected Bn port connects to A with 5 Ω Ron and 0.24 ns tpd. This enables precise timing-controlled bus isolation in multi-master systems.