Texas Instruments SN74CB3Q3245PWRE4

Overview

SN74CB3Q3245 from Texas Instruments is an 8-bit FET bus switch optimized for high-bandwidth, low-voltage digital signal routing in 2.5-V/3.3-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 PCI interface, memory interleaving, and bus isolation applications.

For engineers reviewing the SN74CB3Q3245 datasheet, SN74CB3Q3245 pinout, SN74CB3Q3245 application, or SN74CB3Q3245 equivalent, key selection criteria include its 20-pin TSSOP (PW) package, Ioff partial-power-down support, 3.5 pF OFF-state I/O capacitance, and compatibility with TTL/3.3-V CMOS control inputs.

Technical Context

The SN74CB3Q3245 employs a charge-pump-enhanced FET architecture to maintain flat, low ON-state resistance across its full 0–5 V I/O voltage range - critical for minimizing signal distortion in high-speed digital buses. Its single OE input controls all eight A↔B bidirectional channels simultaneously, with near-zero propagation delay due to minimal RC time constant (ron × Cio).

Designed for partial-power-down operation, the device integrates Ioff circuitry that blocks backflow current when VCC = 0 V while maintaining 5-V signal integrity on unpowered I/Os. The internal undershoot clamp diodes and 5-V-tolerant I/O structure allow interoperability across mixed-voltage domains without level shifters.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.5 mm × 4.4 mm, 1.2 mm max height, 0.65 mm pitch, exposed thermal pad not present (unlike RGY/QFN variants). Pin 1 index located at top-left corner with beveled edge marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDTQS3VH384 and SN74CBTLV3245PWR, the SN74CB3Q3245 provides superior high-frequency fidelity (500 MHz vs. 350 MHz), lower ON-resistance (4 Ω vs. 5 Ω), and tighter Cio control (3.5 pF vs. 4.5 pF), making it optimal for next-generation memory and interconnect applications demanding minimal signal degradation.

Availability

SN74CB3Q3245 is available at Aetrix Electronics and suitable for PCI interface design, memory interleaving architectures, and bus isolation circuits requiring stable component supply, long-term manufacturability, and guaranteed RoHS-compliant sourcing.

Supply support for SN74CB3Q3245 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 IC design and manufacturing.

The SN74CB3Q3245 belongs to TI's CB3Q family of high-bandwidth FET bus switches, engineered specifically for low-distortion, rail-to-rail signal gating 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 high-frequency data path, validated by TI's characterization of propagation delay (0.12–0.20 ns) and ON-state resistance flatness. This enables reliable use in PCI, DDR, and high-speed serial link applications where signal integrity is critical. The SN74CB3Q3245 achieves this via charge-pump gate drive and ultra-low 3.5 pF OFF-state capacitance.

Does the SN74CB3Q3245 support partial power-down operation?

Yes, the SN74CB3Q3245 features integrated Ioff circuitry that limits back-current to ≤1 µA when VCC = 0 V, allowing safe operation in partial-power-down systems. This capability ensures isolation between powered and unpowered sections of a board - a key requirement for hot-swap and battery-backed subsystems. The SN74CB3Q3245 maintains 5-V signal tolerance on I/Os even during VCC absence.

Can the SN74CB3Q3245 interface between 1.8-V and 3.3-V logic domains?

Yes, the SN74CB3Q3245 supports 0–5 V signaling on A/B ports independent of VCC, enabling seamless interfacing between 1.8-V, 2.5-V, 3.3-V, and 5-V logic families. Its 5-V-tolerant I/Os and rail-to-rail switching capability mean the SN74CB3Q3245 can pass signals bidirectionally without level-shifting circuitry - provided VCC is within 2.3–3.6 V for internal logic operation.

What is the purpose of the NC pins on the SN74CB3Q3245 PW package?

Pins 1 and 20 of the SN74CB3Q3245 in TSSOP (PW) package are designated NC (No internal connection) - they have no electrical function and must remain unconnected. TI recommends leaving them floating or tying them to GND/VCC only for mechanical stability or EMI reduction; connecting them to active signals risks undefined behavior. The SN74CB3Q3245 datasheet explicitly states these pins are internally unconnected.

How does the SN74CB3Q3245 differ from the SN74CBTLV3245?

The SN74CB3Q3245 offers lower ON-state resistance (4 Ω vs. 5 Ω typical), lower OFF-state I/O capacitance (3.5 pF vs. 4.5 pF), and higher bandwidth (500 MHz vs. ~350 MHz) than the SN74CBTLV3245. Both share identical pinout and VCC range, but the SN74CB3Q3245 uses an enhanced charge-pump architecture for flatter ron vs. VI characteristics - making the SN74CB3Q3245 preferable for high-fidelity, high-speed applications.