Texas Instruments SN74CB3Q3251DGVR

Overview

SN74CB3Q3251DGVR from Texas Instruments is a 1-of-8 FET multiplexer/demultiplexer bus switch optimized for high-bandwidth, low-voltage operation at 2.5 V and 3.3 V. It features 4 Ω typical ON-state resistance (ron), 500 MHz bandwidth support, 5-V tolerant I/Os, rail-to-rail switching, and bidirectional data flow. It serves as a signal-gating interface in PCI, memory interleaving, and bus isolation systems.

For engineers reviewing the SN74CB3Q3251DGVR datasheet, SN74CB3Q3251DGVR pinout, SN74CB3Q3251DGVR application, or SN74CB3Q3251DGVR equivalent, key selection criteria include its 16-pin TVSOP package, 3.5 pF typical OFF-state I/O capacitance, partial-power-down Ioff capability, 0.12 ns typical propagation delay, and compatibility with 0–5 V signaling across mixed-voltage domains.

Technical Context

The SN74CB3Q3251DGVR implements an integrated charge-pump circuit to elevate the gate voltage of its pass transistors, enabling flat, low ron over full input voltage range (0–5.5 V) and supply voltages from 2.3 V to 3.6 V. Its architecture supports bidirectional signal routing without direction control pins.

Three select inputs (S0–S2) configure one of eight B-port connections to the A port, while OE enables/disables the switch path. The device maintains high-impedance isolation when disabled and supports hot-insertion via Ioff protection, preventing backflow current during partial power-down.

Key Specifications

Pinout & Package

SN74CB3Q3251DGVR uses a 16-pin Thin Very Small Outline Package (TVSOP, DGV), 4.9 mm × 3.9 mm body, 0.65 mm lead pitch, 1.2 mm max height, JEDEC MO-153 compliant. Pin 1 located at top-left corner (quadrant Q1) per tape-and-reel orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDTQS3VH251, SN74CB3Q3251DGVR offers identical electrical performance and drop-in compatibility, while SN74CB3Q3257PWR provides architectural flexibility for dual-switch topologies at the cost of functional re-architecting.

Availability

SN74CB3Q3251DGVR is available at Aetrix Electronics and suitable for PCI interface design, memory interleaving systems, and bus isolation applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SN74CB3Q3251DGVR 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 high-performance logic solutions, with decades of expertise in signal-integrity-critical interface ICs.

The SN74CB3Q3251DGVR belongs to TI's CB3Q bus switch family, engineered specifically for high-bandwidth, low-distortion signal routing in computing, networking, and communications infrastructure where timing precision and voltage-domain interoperability are essential.

FAQ

What is the maximum operating frequency supported by the SN74CB3Q3251DGVR?

The SN74CB3Q3251DGVR supports up to 500 MHz bandwidth for signal pass-through and up to 20 MHz for control inputs (OE or S0–S2). These values reflect measured performance under recommended conditions (VCC = 3.3 V, CL = 50 pF), enabling use in high-speed digital interconnects without added latency or distortion. The 500 MHz figure derives from characterization of insertion loss and group delay across the ON-state path.

Does the SN74CB3Q3251DGVR support hot-swap or partial-power-down operation?

Yes, the SN74CB3Q3251DGVR supports partial-power-down via its Ioff feature: when VCC = 0 V, leakage current remains ≤1 µA even with 0–5.5 V applied to I/O pins. This prevents back-current flow and enables safe hot-insertion into live backplanes. TI validates this per JESD78 Class II latch-up standards, making SN74CB3Q3251DGVR suitable for modular server and telecom chassis designs.

What is the significance of the NC pin on the SN74CB3Q3251DGVR?

Pin 16 of the SN74CB3Q3251DGVR is marked NC (No internal connection). It has no bond wire or silicon connection and must be left unconnected on the PCB. Routing traces or placing vias to this pin may introduce parasitic capacitance or noise coupling; TI's mechanical drawings and layout guidelines explicitly require NC pins to remain floating to maintain specified Cio(OFF) and signal integrity.

Can the SN74CB3Q3251DGVR interface between 1.8-V and 3.3-V logic domains?

Yes, the SN74CB3Q3251DGVR supports 0–5 V signaling on all I/Os regardless of VCC (2.3–3.6 V), enabling direct interfacing between 1.8-V, 2.5-V, and 3.3-V domains without external level shifters. Its control inputs accept TTL/CMOS thresholds (VIH = 2.0 V min at VCC ≥ 2.7 V), and its bidirectional data path preserves voltage levels end-to-end-verified in TI application report SCDA008.

How does the charge-pump circuit in the SN74CB3Q3251DGVR improve performance?

The integrated charge pump in the SN74CB3Q3251DGVR elevates the gate voltage of the internal FET pass transistors above VCC, ensuring strong enhancement-mode conduction across the full 0–5.5 V I/O range. This delivers flat 4 Ω ron independent of signal swing-unlike standard transmission gates-and eliminates body-diode conduction, enabling true rail-to-rail analog/digital switching with sub-ns propagation delay.