Texas Instruments SN74CB3Q16811DGGR

Overview

SN74CB3Q16811DGGR from Texas Instruments is a 24-bit FET bus switch with precharged B-port outputs, designed for high-bandwidth bidirectional signal routing in 2.5-V/3.3-V systems. It features 5 Ω typical ON-state resistance, 4 pF OFF-state I/O capacitance, 5-V-tolerant I/Os, and supports rail-to-rail 0- to 5-V signaling - enabling PCI Hot Plug, memory interleaving, and bus isolation in networking and computing backplanes.

For engineers reviewing the SN74CB3Q16811DGGR datasheet, SN74CB3Q16811DGGR pinout, SN74CB3Q16811DGGR application, or SN74CB3Q16811DGGR equivalent, key selection criteria include precharge bias voltage (BIASV) support for live-insertion noise suppression, partial-power-down Ioff capability, flat ron over voltage range, and TSSOP-56 package compatibility with high-density PCB layouts.

Technical Context

This device integrates two independent 12-bit bus switches, each controlled by dedicated OE inputs (1OE, 2OE), allowing flexible partitioning as either dual 12-bit or single 24-bit switching paths. Its charge-pump gate drive enables low, flat ON-resistance across VCC = 2.3 V to 3.6 V and input voltages from 0 V to 5.5 V.

The B-port outputs are internally precharged via a 10-kΩ-equivalent path to BIASV (0–5 V), minimizing signal distortion during hot-plug events. Ioff circuitry blocks current backflow when VCC = 0 V, supporting true partial-power-down operation per JESD78 Class II latch-up compliance.

Key Specifications

Pinout & Package

TSSOP-56 package (DGG), 1.2 mm max height, 0.5 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-1 (unlimited reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDTQS3VH16811PAG and SN74CBTLV16212DGGR, the SN74CB3Q16811DGGR uniquely combines precharge-enabled glitch suppression, –1.8-V undershoot clamping, and verified Ioff at VCC = 0 V - making it the only option qualified for standards-compliant PCI Hot Plug and partial-power-down systems without design compromises.

Availability

SN74CB3Q16811DGGR is available at Aetrix Electronics and suitable for PCI Hot Plug interfaces, memory interleaving subsystems, and multi-voltage I/O bridging requiring stable component supply across extended temperature ranges (–40°C to +85°C) and long production lifecycles.

Supply support for SN74CB3Q16811DGGR 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-reliability interface solutions.

The SN74CB3Q16811DGGR belongs to TI's Widebus™ family of high-speed FET bus switches, engineered specifically for bandwidth-critical applications including hot-pluggable computing infrastructure, telecom backplanes, and mixed-voltage industrial control systems.

FAQ

What is the purpose of the BIASV pin on the SN74CB3Q16811DGGR?

The BIASV pin sets the precharge voltage for the B-port outputs. When an output-enable signal is deasserted (OE = H) or VCC is removed, the B-port is pulled to BIASV through an internal ~10-kΩ path. This prevents floating-bus conditions and suppresses live-insertion glitches by ensuring the B-port remains outside the input threshold region of downstream receivers - a critical requirement for PCI Hot Plug compliance. For optimal performance, BIASV should match the receiver's input switching threshold.

Can the SN74CB3Q16811DGGR operate with VCC = 2.5 V while switching 5-V signals on the I/O ports?

Yes, the SN74CB3Q16811DGGR supports 0- to 5-V signaling on all data I/Os (A and B ports) with VCC as low as 2.3 V. At VCC = 2.5 V, its typical ON-state resistance remains 5 Ω, and VI/O tolerance extends to 5.5 V - enabling direct interfacing between low-voltage controllers (e.g., 2.5-V FPGA banks) and 5-V peripherals without external level-shifting circuitry. Control inputs also accept TTL/CMOS levels across the full VCC range.

How does the Ioff feature of the SN74CB3Q16811DGGR protect the system during partial power-down?

The Ioff circuitry in the SN74CB3Q16811DGGR actively disables current paths when VCC = 0 V, limiting reverse current through the switch to ≤1 µA even if 5-V signals remain present on A or B ports. This prevents back-driving powered-down sections of the system, avoids unintended logic states, and eliminates risk of damage to unpowered ICs - a necessity for reliable hot-swap and modular power architecture designs.

Is the SN74CB3Q16811DGGR pin-compatible with other devices in the SN74CB3Q family?

Yes, the SN74CB3Q16811DGGR shares identical pinout, package (TSSOP-56), and functional block diagram with other members of the SN74CB3Q16xxx series, including SN74CB3Q16210 and SN74CB3Q16244 in the same DGG package. All support the same BIASV precharge architecture, Ioff, and 5-V-tolerant I/Os - enabling drop-in replacement within the family for bandwidth or channel-count optimization.

What is the maximum recommended switching frequency for the SN74CB3Q16811DGGR?

The SN74CB3Q16811DGGR supports up to 20 MHz maximum switching frequency on its OE control inputs under standard test conditions (VO > VCC, VI = 5 V, RL ≥1 MΩ, CL = 0). In practical PCB implementations with typical trace capacitance (≤5 pF), sustained operation at 15–18 MHz is achievable. Propagation delay remains stable at 0.09–0.15 ns due to flat ron, making it suitable for high-speed burst-mode data gating in networking and storage applications.