Texas Instruments SN74CB3Q3257PWR

Overview

SN74CB3Q3257PWR from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer optimized for high-bandwidth bus switching, featuring 4 Ω typical on-state resistance (ron), 500 MHz bandwidth support, 5 V-tolerant I/Os with device powered up or down, rail-to-rail 0–5 V signal switching at 3.3 V VCC, and bidirectional near-zero-propagation-delay data flow. It serves in high-speed digital interconnects such as optical networking and USB interface isolation.

For engineers reviewing the SN74CB3Q3257PWR datasheet, SN74CB3Q3257PWR pinout, SN74CB3Q3257PWR application, or SN74CB3Q3257PWR equivalent, key selection considerations include its 2.3–3.6 V VCC range, 3.5 pF typical OFF-state I/O capacitance, Ioff partial-power-down capability, 20 MHz maximum OE switching frequency, and TSSOP-16 package compatibility with space-constrained PCB layouts.

Technical Context

The SN74CB3Q3257PWR implements four independent 1-of-2 analog/digital switches using charge-pump-enhanced FET pass transistors to maintain flat, low ron across voltage and temperature. Each channel features separate select (S) and output-enable (OE) control, enabling independent routing of 4-bit buses between two destinations.

Its architecture supports true bidirectional signal flow without direction pins, leverages undershoot clamp diodes on all I/O and control inputs, and guarantees isolation during power-off via Ioff circuitry-preventing backflow current when VCC = 0 V while maintaining 0–5 V I/O tolerance.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package: 5.0 mm × 6.4 mm body, 0.65 mm lead pitch, exposed thermal pad not present, RoHS-compliant NiPdAu/Sn lead finish, MSL Level-1 (unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3Q3257PWR, SN74CBT3257PWR trades bandwidth and voltage flexibility for lower cost, while TS3DS10224RTER reduces integration density and removes Ioff safety-making SN74CB3Q3257PWR the optimal choice for industrial-grade, mixed-voltage, high-reliability bus switching.

Availability

SN74CB3Q3257PWR is available at Aetrix Electronics and suitable for optical networking, USB interface isolation, and wireless infrastructure applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for SN74CB3Q3257PWR 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 precision analog design and high-speed interface solutions.

The SN74CB3Q3257PWR belongs to TI's CB3Q family of high-bandwidth FET bus switches, engineered specifically for low-distortion, rail-to-rail signal routing in broadband communications, optical transport, and high-speed digital interconnect systems.

FAQ

What is the maximum signal frequency supported by the SN74CB3Q3257PWR?

The SN74CB3Q3257PWR supports signal frequencies up to 500 MHz, verified under load conditions with matched impedance and proper PCB layout. This bandwidth is enabled by its 4 Ω typical on-state resistance and 3.5 pF typical OFF-state I/O capacitance, which jointly minimize RC delay and signal distortion. Performance remains consistent across the full –40 °C to 105 °C operating temperature range.

Does the SN74CB3Q3257PWR support hot-swap or live-insertion scenarios?

Yes, the SN74CB3Q3257PWR supports hot-swap operation due to its 5 V-tolerant I/Os-functional even when VCC = 0 V-and integrated Ioff circuitry that blocks reverse current flow during partial power-down. This ensures safe insertion/removal in modular backplanes and pluggable optical modules without damaging upstream or downstream circuitry.

Can the SN74CB3Q3257PWR operate with a 2.5 V supply voltage?

Yes, the SN74CB3Q3257PWR is fully specified for 2.3 V to 3.6 V VCC operation, including 2.5 V. At 2.5 V, it supports 0–3.3 V rail-to-rail switching and delivers 4 Ω typical ron. Switching characteristics-including 10 MHz maximum f_OE and sub-0.21 ns propagation delay-are guaranteed across this range per TI's SCDS135E datasheet.

How does the charge pump in the SN74CB3Q3257PWR improve performance?

The internal charge pump in the SN74CB3Q3257PWR elevates the gate voltage of the FET pass transistors above VCC, ensuring strong enhancement-mode conduction across the entire 2.3–3.6 V supply range. This results in flat, low on-state resistance (4 Ω typical) and stable 500 MHz bandwidth-unlike non-charge-pump switches whose ron degrades significantly below 3.0 V.

Is the SN74CB3Q3257PWR pin-compatible with other members of the CB3Q family?

Yes, the SN74CB3Q3257PWR shares identical pinout, function mapping, and package dimensions (TSSOP-16) with all CB3Q-series 4-bit 2:1 mux/demux variants-including SN74CB3Q3257DBQR (SSOP), SN74CB3Q3257DGVR (TVSOP), and SN74CB3Q3257RGYR (VQFN). This enables drop-in replacement across form factors without PCB redesign.