Texas Instruments SN74CB3Q3345PWR

Overview

SN74CB3Q3345PWR 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 between A and B ports in memory interleaving, bus isolation, and differential interface applications.

For engineers reviewing the SN74CB3Q3345PWR datasheet, SN74CB3Q3345PWR pinout, SN74CB3Q3345PWR application, or SN74CB3Q3345PWR equivalent, key selection considerations include its 20-pin TSSOP (PW) package, dual OE control logic, Ioff partial-power-down support, and 500 MHz bandwidth capability under 3.3-V operation.

Technical Context

The SN74CB3Q3345PWR uses a charge-pump-enhanced FET architecture to maintain flat, low ON-state resistance across input voltage ranges (0–5 V), ensuring minimal signal distortion and near-zero propagation delay. Its dual active-high/active-low OE inputs enable flexible bus gating control with independent enable/disable timing.

Designed for hot-swap and partial-power-down environments, the device features Ioff protection that blocks current backflow when VCC = 0 V, and 5-V-tolerant I/Os remain functional regardless of supply state. Control inputs accept TTL- or CMOS-level signals, supporting interoperability with legacy and mixed-voltage systems.

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), RoHS-compliant NiPdAu finish, MSL Level-1 (unlimited reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3T3345PWR and SN74LVC1G3157DCKR, the SN74CB3Q3345PWR uniquely combines 8-bit parallel architecture, charge-pump-enhanced 4 Ω ron, dual OE logic, and guaranteed 500 MHz bandwidth - making it the sole option for high-fidelity, low-latency bus switching in demanding computing and communications systems.

Availability

SN74CB3Q3345PWR is available at Aetrix Electronics and suitable for memory subsystems, industrial backplanes, high-speed video interfaces, and audio SoC designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for SN74CB3Q3345PWR 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 50 years of innovation in high-performance interface solutions.

The SN74CB3Q3345PWR belongs to TI's CB3Q family of charge-pump FET bus switches, engineered specifically for low-latency, high-bandwidth digital signal routing in broadband communications, networking infrastructure, and data-intensive computing platforms.

FAQ

What is the maximum operating frequency supported by the SN74CB3Q3345PWR?

The SN74CB3Q3345PWR supports a maximum OE switching frequency of 20 MHz and is characterized for high-bandwidth signal routing up to 500 MHz. This 500 MHz rating reflects its ability to pass high-frequency digital waveforms with minimal attenuation or phase distortion - verified via ron flatness and Cio(OFF) metrics - not a clock frequency specification. The device does not contain internal clock circuitry.

Does the SN74CB3Q3345PWR require external pull-up or pull-down resistors on OE pins?

Yes - to ensure a defined high-impedance state during power-up or power-down, OE should be tied to VCC through a pull-up resistor and OE should be tied to GND through a pull-down resistor. TI recommends minimum resistor values based on driver strength; typical values range from 4.7 kΩ to 10 kΩ. Leaving either OE pin floating risks undefined bus states and potential signal contention.

Can the SN74CB3Q3345PWR safely interface between 1.8-V and 5-V logic domains?

Yes - the SN74CB3Q3345PWR supports 0–5.5 V signaling on all A and B I/O pins 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 I/Os do not require external level shifters, and undershoot clamp diodes protect against negative transients down to –1.8 V.

What is the thermal performance of the SN74CB3Q3345PWR in its TSSOP-20 (PW) package?

The SN74CB3Q3345PWR in the PW package has a junction-to-ambient thermal resistance (θJA) of 83°C/W, measured per JESD 51-7. With typical ICC = 0.7 mA at 3.3 V, power dissipation remains below 2.5 mW - resulting in negligible self-heating under normal operation. No heatsink or forced airflow is required for standard industrial temperature operation (–40°C to 85°C).

How does the Ioff feature of the SN74CB3Q3345PWR protect system-level power sequencing?

The Ioff circuitry in the SN74CB3Q3345PWR actively blocks current flow between A and B ports when VCC = 0 V, limiting reverse current to ≤1 µA. This prevents damaging backfeed from powered downstream circuits into unpowered upstream domains - a critical safeguard during hot-plug events, staggered power-up sequences, or partial system resets in multi-rail embedded systems.