Texas Instruments SN74CB3Q3245RGYR

Overview

SN74CB3Q3245 from Texas Instruments is an 8-bit FET bus switch optimized for high-bandwidth, low-voltage digital signal routing in 2.3–3.6 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 signal gating in PCI interfaces, memory interleaving, and bus isolation applications.

For engineers reviewing the SN74CB3Q3245 datasheet, SN74CB3Q3245 pinout, SN74CB3Q3245 application, or SN74CB3Q3245 equivalent, key selection considerations include its 20-pin VQFN (RGY) package, Ioff partial-power-down support, 3.5 pF OFF-state I/O capacitance, and compatibility with 1.2 V to 5 V signaling levels across mixed-voltage domains.

Technical Context

The SN74CB3Q3245 implements a charge-pump-enhanced FET architecture to maintain flat, low ON-state resistance (4–8 Ω) across input voltages from 0 V to VCC, enabling distortion-free analog/digital signal pass-through. Its single OE control enables synchronous 8-bit channel enable/disable with 1.5–6.5 ns enable/disable times.

Designed for voltage-translation-agnostic operation, it supports 0–5 V data I/Os regardless of VCC (2.5 V or 3.3 V), while featuring undershoot clamp diodes, 5-V-tolerant control inputs, and JESD78 Class II latch-up immunity - critical for hot-swap and mixed-supply system interconnects.

Key Specifications

Pinout & Package

VQFN-20 (RGY) package: 3.5 mm × 4.5 mm, 0.5 mm pitch, 1 mm max height, with 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 IDTQS3VH384, SN74CB3Q3245 offers identical electrical performance and TI's extended lifecycle support; versus SN74CBTLV3245PWR, it delivers superior bandwidth, flatter ron, and true 0–5 V signal handling - making it the preferred choice for high-fidelity, mixed-voltage interconnects.

Availability

SN74CB3Q3245RGYR is available at Aetrix Electronics and suitable for PCI interface design, memory subsystem routing, and bus isolation applications requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for SN74CB3Q3245RGYR 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 SN74CB3Q3245 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, networking infrastructure, and data-intensive computing platforms.

FAQ

What is the maximum operating frequency supported by the SN74CB3Q3245?

The SN74CB3Q3245 supports up to 500 MHz bandwidth in its data path due to low 4 Ω ON-state resistance and 3.5 pF OFF-state capacitance. Its OE control input operates up to 20 MHz, enabling rapid bus enable/disable cycles. These values are measured under recommended conditions (VCC = 3.3 V, TA = 25°C) and reflect actual signal integrity performance - not theoretical limits.

Does the SN74CB3Q3245 require external level shifters when interfacing 1.8 V and 5 V systems?

No, the SN74CB3Q3245 does not require external level shifters. Its 0–5.5 V data I/O voltage range and 5-V-tolerant inputs allow direct connection between 1.2 V, 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains while powered from 2.5 V or 3.3 V. This capability is inherent to its FET architecture and charge-pump design - confirmed in the absolute maximum ratings and recommended operating conditions tables.

How does the Ioff feature protect circuits during partial power-down?

The Ioff feature in the SN74CB3Q3245 limits current flow to ≤1 µA when VCC = 0 V and any I/O is biased between 0–5.5 V. This prevents damaging back-current from live buses into unpowered sections - a critical requirement for hot-swap, modular systems, and power-gated SoC domains. The specification is validated per JESD78 Class II latch-up testing and applies regardless of OE state.

What is the purpose of the exposed thermal pad (Pin 21) on the RGY package of the SN74CB3Q3245?

The exposed thermal pad (Pin 21) on the SN74CB3Q3245RGYR's VQFN package must be soldered to a PCB copper pour for thermal dissipation and mechanical stability. It is electrically connected to GND internally and improves thermal resistance (θJA = 37°C/W) - essential for maintaining junction temperature within safe limits during sustained 64 mA per channel operation. Layout guidelines specify minimum solder coverage (78%) and optional thermal vias.

Can the SN74CB3Q3245 be used for analog signal switching, such as audio or clock distribution?

Yes, the SN74CB3Q3245 is qualified for analog signal switching including clock distribution and low-frequency audio paths. Its rail-to-rail operation, flat 4 Ω ron, low 3.5 pF OFF-capacitance, and absence of body-diode conduction (enabled by charge pump) preserve signal linearity and edge integrity. TI explicitly lists "support for both digital and analog applications" in the device description, and characterization data confirms consistent performance across 0–5 V input ranges.