Texas Instruments SN74CB3Q3257DGVR

Overview

SN74CB3Q3257DGVR from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer bus switch optimized for high-bandwidth signal routing in low-voltage systems. It delivers rail-to-rail 0–5V switching at 3.3V VCC, features 4Ω typical on-state resistance (ron), supports up to 500MHz data path bandwidth, and enables bidirectional signal flow with near-zero propagation delay - deployed in optical networking and USB interface isolation.

For engineers reviewing the SN74CB3Q3257DGVR datasheet, SN74CB3Q3257DGVR pinout, SN74CB3Q3257DGVR application, or SN74CB3Q3257DGVR equivalent, key selection criteria include its 5V-tolerant I/Os under powered-up/down conditions, Ioff partial-power-down support, low 3.5pF off-state I/O capacitance, 20MHz maximum OE switching frequency, and compatibility with 2.3V–3.6V supply rails across industrial temperature range (–40°C to 105°C).

Technical Context

The SN74CB3Q3257DGVR 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 has dedicated select (S) and output-enable (OE) inputs, enabling per-channel control of bidirectional signal paths between common A ports and dual B ports (B1/B2).

Its architecture supports simultaneous 4-bit multiplexing or demultiplexing with rail-to-rail operation: 0–5V signaling at 3.3V VCC and 0–3.3V at 2.5V VCC. The device integrates undershoot clamp diodes on all data and control inputs, and uses Ioff circuitry to block current backflow during partial power-down - critical for hot-swap and system-level power sequencing.

Key Specifications

Pinout & Package

SN74CB3Q3257DGVR is housed in a 16-pin TVSOP (DGV) package measuring 3.6mm × 6.4mm with exposed thermal pad, rated MSL Level-1 (unlimited floor life), and RoHS-compliant NiPdAu lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3Q3257DGVR, SN74CBT3257PWR trades 5V I/O tolerance and charge-pump ron flatness for wider VCC flexibility, while TS3A227EYZTR sacrifices bandwidth and 5V tolerance to integrate higher ESD protection - making SN74CB3Q3257DGVR optimal for high-speed, hot-pluggable telecom and networking signal routing.

Availability

SN74CB3Q3257DGVR is available at Aetrix Electronics and suitable for optical networking, USB 2.0 interface isolation, and IP phone audio routing requiring stable component supply across industrial temperature grades and long-lifecycle production programs.

Supply support for SN74CB3Q3257DGVR 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 decades of expertise in high-performance signal-switching solutions.

The SN74CB3Q3257DGVR belongs to TI's CB3Q family of high-bandwidth FET bus switches, designed specifically for low-distortion, rail-to-rail signal routing in broadband communications, optical infrastructure, and high-speed digital interconnects.

FAQ

What is the maximum signal frequency supported by the SN74CB3Q3257DGVR?

The SN74CB3Q3257DGVR supports a high-bandwidth data path up to 500MHz, verified under typical operating conditions with 3.3V VCC and matched 50Ω loads. Its low 4Ω ron and 3.5pF off-state capacitance preserve signal integrity at these frequencies, making it suitable for USB 2.0, EPON, and video-over-fiber applications where minimal insertion loss and jitter are critical. Actual usable bandwidth depends on PCB layout and termination.

Does the SN74CB3Q3257DGVR support 5V-tolerant I/Os when powered down?

Yes, the SN74CB3Q3257DGVR maintains 5V tolerance on all I/O pins (A, B1, B2) even when VCC = 0V - a key feature confirmed in its Absolute Maximum Ratings (VI/O = –0.5V to 7V) and Functional Description. This enables safe hot-plug operation and prevents damage during partial power-down sequences in modular systems, unlike standard CMOS switches that risk latch-up or leakage.

How does the charge pump in the SN74CB3Q3257DGVR improve performance?

The integrated charge pump in the SN74CB3Q3257DGVR elevates the gate voltage of the internal FET pass transistors, ensuring strong turn-on across the full 2.3V–3.6V VCC range. This delivers flat, low 4Ω typical ron independent of input signal voltage - directly enabling rail-to-rail 0–5V switching at 3.3V VCC and minimizing propagation delay variation, which is essential for timing-critical multiplexing in telecom and computing interfaces.

Can the SN74CB3Q3257DGVR be used in analog signal routing applications?

Yes, the SN74CB3Q3257DGVR is explicitly qualified for both digital and analog use cases, including differential signal interfaces and low-distortion signal gating. Its low ron (4Ω), low Cio(OFF) (3.5pF), and rail-to-rail capability support clean analog switching of audio, video, and sensor signals up to 500MHz. TI's documentation confirms suitability for USB, EPON, and other analog-digital hybrid interfaces requiring minimal THD and crosstalk.

What is the thermal performance of the SN74CB3Q3257DGVR in its TVSOP package?

The SN74CB3Q3257DGVR in TVSOP (DGV) package has a junction-to-ambient thermal resistance (RθJA) of 126.0°C/W and junction-to-board (RθJB) of 57.8°C/W, per TI's thermal metrics report. With its exposed thermal pad and MSL Level-1 rating, it sustains continuous operation at 105°C ambient when properly soldered to a 2-layer PCB with ≥2 cm² copper pour - validated for optical module and PBX applications demanding extended thermal reliability.