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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SN74CBT3257PWR

Name: SN74CBT3257PWR
Brand: Texas Instruments
SKU: SN74CBT3257PWR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74CBT3257PWR

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-TSSOP (0.173", 4.40mm Width)

Datasheet:: SN74CBT3257PWR.pdf

Description:: IC MUX/DEMUX 4 X 2:1 16TSSOP

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Product details

Overview

SN74CBT3257PWR from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer with 5 Ω on-state resistance, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and 0.25 ns typical propagation delay at 5 V. It operates from −40°C to 85°C and supports bidirectional signal routing in high-speed digital interconnects such as bus isolation and data path switching.

For engineers reviewing the SN74CBT3257PWR datasheet, SN74CBT3257PWR pinout, SN74CBT3257PWR application, or SN74CBT3257PWR equivalent, key selection criteria include on-resistance matching across channels, OE/S-controlled channel selection timing, bidirectional low-capacitance switching (Cio(OFF) = 4 pF), and TSSOP-16 thermal performance (θJA = 108°C/W).

Technical Context

The SN74CBT3257PWR implements four independent analog switches using NMOS pass transistors with complementary drive, enabling true bidirectional operation without direction pins. Each switch connects one A-terminal to either B1 or B2 based on the S input, while OE enables or disables all channels simultaneously.

Its TTL-compatible control logic accepts 2 V VIH and 0.8 V VIL thresholds, ensuring interoperability with legacy 5-V logic families. The device draws only 3 μA ICC at 5.5 V and exhibits minimal charge injection (<0.5 pC typical), supporting clean signal integrity in mixed-signal routing applications.

Key Specifications

Parameter	Value and Actual Design Meaning
On-state resistance (ron)	5–7 Ω at 4.5 V - ensures minimal voltage drop and signal attenuation for 3.3/5-V digital signals.
Propagation delay (tpd)	0.25 ns at VCC = 5 V - enables sub-nanosecond switching for high-speed bus arbitration and clock domain crossing.
Off-state capacitance (Cio(OFF))	4 pF - limits crosstalk and maintains signal integrity when channels are disabled.
Supply voltage range	4–5.5 V - compatible with standard 5-V logic rails and tolerant of minor supply variation.
Input capacitance (Ci)	3.5 pF - reduces loading on driving logic and preserves edge rates in fan-out-critical paths.
Channel current rating	128 mA continuous - supports robust signal routing for GPIO expansion and peripheral multiplexing.
Operating temperature	−40°C to 85°C - qualified for industrial-grade embedded systems and communication equipment.

Pinout & Package

TSSOP-16 package (PW), 5.0 mm × 4.4 mm × 1.2 mm height, exposed pad not present, JEDEC MO-153 compliant.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 6, 11, 12, 13, 14, 15, 16	Data terminals (1A–4A, 1B1–4B1, 1B2–4B2)	Bidirectional analog/digital signal paths; no internal directionality - identical electrical behavior in both directions.
7	GND	Power return reference for all switch channels and control circuitry.
8	VCC	Positive supply rail (4–5.5 V); powers internal level shifters and pass transistor gates.
9	OE	Active-low output enable; drives all four switches into high-impedance state when high.
10	S	Select control; determines whether A-port connects to B1 (S = L) or B2 (S = H) for all channels.

Key Features

Feature	Design Value
Low on-resistance	5–7 Ω ensures <50 mV voltage drop at 10 mA, preserving logic-level margins in 5-V systems.
TTL-compatible inputs	VIH = 2 V / VIL = 0.8 V allows direct interface with 74LS, 74ALS, and microcontroller GPIO without level shifters.
Bidirectional operation	No direction pin required - same electrical characteristics regardless of signal flow direction (A→B or B→A).
Fast switching	0.25 ns tpd at 5 V enables use in >1 GHz data path gating and real-time bus arbitration circuits.
Low off-capacitance	4 pF Cio(OFF) minimizes capacitive coupling between active and inactive channels in dense PCB layouts.

Applications

PCI Express Lane Multiplexing	Legacy Bus Isolation
Use Scenario: Dynamically rerouting PCIe Gen1/Gen2 lanes between two host controllers or endpoints during system reconfiguration. IC Role / Device Role / Timing Role: Bidirectional 1-of-2 analog switch providing lane-level signal path selection with sub-nanosecond timing control. Use Value: Enables hardware-based PCIe topology switching without retiming or protocol translation, preserving link training integrity.	Use Scenario: Isolating shared address/data buses between microcontroller peripherals (e.g., SPI flash, UART, I²C EEPROM) to prevent contention. IC Role / Device Role / Timing Role: Low-resistance, low-capacitance bus switch controlled by GPIO-driven OE and S signals. Use Value: Eliminates need for tristate buffers or discrete MOSFETs while maintaining signal rise/fall times under 1 ns.
Test Access Multiplexing	Signal Path Calibration Switching
Use Scenario: Routing JTAG or boundary-scan test signals to multiple ICs on a densely populated board using a single debug header. IC Role / Device Role / Timing Role: High-isolation analog switch enabling selective connection of TCK/TMS/TDI/TDO lines to target devices. Use Value: Reduces test fixture complexity and eliminates manual jumpering; 4-pF off-capacitance prevents signal degradation at 10 MHz TCK rates.	Use Scenario: Switching reference signals (e.g., DAC outputs, sensor excitation voltages) between calibration standards and DUT inputs in automated test equipment. IC Role / Device Role / Timing Role: Precision analog path selector with matched on-resistance across all four channels. Use Value: Ensures ≤0.5% gain error between calibration and measurement paths due to consistent ron tracking (±0.5 Ω max deviation).

PCI Express Lane Multiplexing

Legacy Bus Isolation

Use Scenario: Dynamically rerouting PCIe Gen1/Gen2 lanes between two host controllers or endpoints during system reconfiguration.

IC Role / Device Role / Timing Role: Bidirectional 1-of-2 analog switch providing lane-level signal path selection with sub-nanosecond timing control.

Use Value: Enables hardware-based PCIe topology switching without retiming or protocol translation, preserving link training integrity.

Use Scenario: Isolating shared address/data buses between microcontroller peripherals (e.g., SPI flash, UART, I²C EEPROM) to prevent contention.

IC Role / Device Role / Timing Role: Low-resistance, low-capacitance bus switch controlled by GPIO-driven OE and S signals.

Use Value: Eliminates need for tristate buffers or discrete MOSFETs while maintaining signal rise/fall times under 1 ns.

Test Access Multiplexing

Signal Path Calibration Switching

Use Scenario: Routing JTAG or boundary-scan test signals to multiple ICs on a densely populated board using a single debug header.

IC Role / Device Role / Timing Role: High-isolation analog switch enabling selective connection of TCK/TMS/TDI/TDO lines to target devices.

Use Value: Reduces test fixture complexity and eliminates manual jumpering; 4-pF off-capacitance prevents signal degradation at 10 MHz TCK rates.

Use Scenario: Switching reference signals (e.g., DAC outputs, sensor excitation voltages) between calibration standards and DUT inputs in automated test equipment.

IC Role / Device Role / Timing Role: Precision analog path selector with matched on-resistance across all four channels.

Use Value: Ensures ≤0.5% gain error between calibration and measurement paths due to consistent ron tracking (±0.5 Ω max deviation).

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74CBTD3384PWR	8-channel, 3.3-V only, higher ron (7–9 Ω), integrated 5-V tolerant level shifters	Requires external level translation for 5-V systems; better suited for 3.3-V-only FPGA I/O banks	Choose when migrating to 3.3-V logic domains and needing double the channel count in same TSSOP-16 footprint.
74LVC1G3157DCKR	Single-channel, 1.65–5.5 V supply, lower ron (3–5 Ω), smaller SC70-6 package	Limited to one 1-of-2 path per device; requires four units to match SN74CBT3257PWR's 4-bit capability	Prefer for space-constrained designs where channel density is secondary to ultra-low on-resistance and wide VCC range.

Compared with SN74CBT3257PWR, SN74CBTD3384PWR offers higher channel density but sacrifices 5-V compatibility and adds level-shifter overhead, while 74LVC1G3157DCKR delivers superior ron and voltage flexibility at the cost of PCB area and component count for multi-bit applications.

Availability

SN74CBT3257PWR is available at Aetrix Electronics and suitable for industrial control backplanes, test instrumentation signal routing, and embedded system bus arbitration requiring stable component supply and long-term lifecycle support.

Supply support for SN74CBT3257PWR 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, specializing in analog, embedded processing, and connectivity technologies with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74CBT3257PWR belongs to TI's CBT (CrossBar Technology) family of high-speed CMOS bus switches, designed specifically for low-latency, bidirectional signal routing in 5-V digital systems where timing predictability and signal fidelity are critical.

FAQ

What is the maximum continuous current rating per channel of the SN74CBT3257PWR?

The SN74CBT3257PWR supports up to 128 mA continuous channel current per switch, verified under absolute maximum ratings. This rating applies to steady-state DC conduction through any individual A-B path and is independent of simultaneous switching on other channels. Exceeding this limit risks thermal overstress and parametric shift in on-resistance. Derating is recommended above 70°C ambient.

Does the SN74CBT3257PWR require external pull-up or pull-down resistors on its control inputs?

No, the SN74CBT3257PWR does not require external biasing on OE or S inputs. Its TTL-compatible thresholds (VIH = 2 V, VIL = 0.8 V) allow direct connection to standard 5-V logic outputs. However, TI recommends tying unused control inputs to VCC or GND per Application Report SCBA004 to prevent floating nodes that could cause increased ICC or erratic switching behavior in the SN74CBT3257PWR.

Can the SN74CBT3257PWR be used to switch analog signals such as audio or sensor outputs?

Yes, the SN74CBT3257PWR supports analog signal routing within its specified voltage range (−0.5 V to VCC + 0.5 V). Its 5–7 Ω on-resistance, 4 pF off-capacitance, and low charge injection (<0.5 pC) make it suitable for audio line-level signals (≤2 Vpp) and low-frequency sensor outputs (DC to ~100 MHz). For precision analog applications, verify THD and crosstalk against system requirements using the SN74CBT3257PWR's published AC characteristics.

What is the thermal resistance (θJA) of the SN74CBT3257PWR in its TSSOP-16 package?

The SN74CBT3257PWR in the PW (TSSOP-16) package has a junction-to-ambient thermal resistance (θJA) of 108°C/W, measured per JESD 51-7 on a standard 2-layer JEDEC test board. This value assumes no copper pour or thermal vias beneath the package. Adding a 100 mm² copper pad with 4× thermal vias reduces effective θJA by ~25°C/W, improving power handling for sustained 100 mA channel loads in the SN74CBT3257PWR.

Is the SN74CBT3257PWR pin-compatible with other members of the SN74CBT3257 family?

Yes, all SN74CBT3257 variants-including SN74CBT3257D, SN74CBT3257DBR, SN74CBT3257DBQR, SN74CBT3257DR, SN74CBT3257PW, and SN74CBT3257PWR-share identical pinouts and electrical specifications. The SN74CBT3257PWR differs only in packaging (TSSOP-16) and tape-and-reel delivery; no redesign or layout change is needed when substituting within the same temperature grade (−40°C to 85°C).

SN74CBT3257PWR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74CBT

Package/Case:: 16-TSSOP (0.173", 4.40mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Multiplexer/Demultiplexer

Circuit:: 4 x 2:1

Independent Circuits:: 1

Current - Output High, Low:: -

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-TSSOP

SN74CBT3257PWR FAQ

1.How can I place an order for SN74CBT3257PWR through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74CBT3257PWR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74CBT3257PWR reliable?

The price and inventory of SN74CBT3257PWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3257PWR is usually 5 days.

3.What payment methods are accepted for SN74CBT3257PWR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74CBT3257PWR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74CBT3257PWR?

SN74CBT3257PWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74CBT3257PWR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74CBT3257PWR?

For technical support, including SN74CBT3257PWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3257PWR requirements.

6.How does Aetrix verify that SN74CBT3257PWR is sourced from the original manufacturer or authorized distributors?

All SN74CBT3257PWR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74CBT3257PWR meets industry standards.

7.What is the process for return or replacement of SN74CBT3257PWR?

All SN74CBT3257PWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3257PWR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74CBT3257PWR part is unused and in its original packaging.

Return procedure for SN74CBT3257PWR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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