Texas Instruments SN74CB3Q3345RGYR

Overview

SN74CB3Q3345RGYR from Texas Instruments is an 8-bit FET bus switch optimized for high-bandwidth, low-voltage digital signal routing in 2.3 V–3.6 V systems. It delivers rail-to-rail switching (0–5 V), 4 Ω typical ON-state resistance, <0.2 ns propagation delay, and 5-V-tolerant I/Os-enabling bidirectional data flow in memory interleaving and differential signal interface applications.

For engineers reviewing the SN74CB3Q3345RGYR datasheet, SN74CB3Q3345RGYR pinout, SN74CB3Q3345RGYR application, or SN74CB3Q3345RGYR equivalent, key selection criteria include its VQFN-20 package thermal performance (θJA = 37°C/W), Ioff partial-power-down capability, 20 MHz maximum OE switching frequency, and 4 pF typical OFF-state I/O capacitance for minimal signal distortion.

Technical Context

The SN74CB3Q3345RGYR implements a charge-pump-enhanced FET architecture to maintain flat, low ON-resistance across input voltage ranges (0–5 V), enabling consistent timing behavior in mixed-voltage systems. Its dual OE/!OE control logic supports both active-high and active-low enable configurations with independent disable paths.

Designed for broadband communications infrastructure, the device features undershoot clamp diodes on all data and control inputs, JESD 22-compliant ESD protection (2000-V HBM), and latch-up immunity exceeding 100 mA per JESD 78 Class II-ensuring robust operation in noisy, hot-plug environments.

Key Specifications

Pinout & Package

VQFN-20 (RGY) package: 3.5 mm × 4.5 mm, 0.5 mm pitch, 1 mm max height, exposed thermal pad (Pin 21) requiring PCB soldering for thermal and mechanical reliability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3Q3345PWR and SN74CB3Q3345DGVR, the SN74CB3Q3345RGYR offers superior thermal management (θJA = 37°C/W) and mechanical stability via its soldered exposed pad-critical for sustained high-bandwidth operation in networking and compute applications.

Availability

SN74CB3Q3345RGYR is available at Aetrix Electronics and suitable for memory interleaving, differential signal interface, and bus isolation applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74CB3Q3345RGYR 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 high-reliability silicon solutions.

The SN74CB3Q3345RGYR belongs to TI's CB3Q family of high-bandwidth FET bus switches, engineered specifically for low-latency, low-distortion signal routing in broadband communications, networking infrastructure, and high-speed computing systems.

FAQ

What is the maximum operating frequency supported by the SN74CB3Q3345RGYR for data signals?

The SN74CB3Q3345RGYR supports data signal bandwidth up to 500 MHz, verified by its low 4 Ω typical ON-state resistance and 4 pF typical OFF-state I/O capacitance. This enables clean transmission of high-speed digital waveforms such as DDR clock strobes and PCIe sideband signals without measurable rise-time degradation.

Does the SN74CB3Q3345RGYR support partial power-down mode, and how is it implemented?

Yes, the SN74CB3Q3345RGYR supports partial power-down via its Ioff circuitry. When VCC = 0 V, leakage current is limited to ≤1 µA per I/O terminal, preventing damaging backflow current into powered sections of the system. This feature is intrinsic to the device structure and requires no external components to activate.

What is the recommended PCB layout practice for the exposed thermal pad on the SN74CB3Q3345RGYR VQFN package?

The exposed thermal pad (Pin 21) of the SN74CB3Q3345RGYR must be soldered to a dedicated PCB copper area connected to GND. TI recommends ≥78% solder paste coverage, thermal vias filled/plugged/tented beneath the pad, and adherence to SLUA271 guidelines to achieve optimal thermal dissipation (θJA = 37°C/W) and mechanical reliability.

Can the SN74CB3Q3345RGYR interface between 1.8-V and 5-V logic domains without external level shifters?

Yes, the SN74CB3Q3345RGYR supports 0–5.5 V signaling on all I/O ports regardless of VCC (2.3–3.6 V), enabling direct connection between 1.8-V, 2.5-V, 3.3-V, and 5-V logic families. Its 5-V-tolerant inputs and rail-to-rail switching eliminate the need for discrete level-shifting circuitry.

How does the charge-pump circuit in the SN74CB3Q3345RGYR improve switching performance compared to standard FET switches?

The integrated charge pump elevates the gate voltage of the pass transistor above VCC, ensuring strong enhancement-mode conduction across the full 0–5 V input range. This maintains flat 4 Ω ron versus voltage-unlike conventional switches whose ron rises sharply near ground or rail-delivering consistent <0.2 ns propagation delay and minimal signal distortion.