Texas Instruments SN74CB3Q3244PW

Overview

SN74CB3Q3244PW from Texas Instruments is a high-bandwidth 8-bit FET bus switch organized as two independent 4-bit bidirectional switches, featuring 4 Ω typical ON-state resistance (ron), rail-to-rail 0–5 V switching at 3.3-V VCC, and 5-V-tolerant I/Os with device powered up or down. It supports broadband communications, memory interleaving, and bus isolation in high-speed digital systems.

For engineers reviewing the SN74CB3Q3244PW datasheet, SN74CB3Q3244PW pinout, SN74CB3Q3244PW application, or SN74CB3Q3244PW equivalent, key selection criteria include partial-power-down Ioff support, low 3.5 pF OFF-state I/O capacitance, sub-0.2 ns propagation delay, 20 MHz max OE switching frequency, and TSSOP-20 package compatibility with industrial temperature range (−40°C to 85°C).

Technical Context

The SN74CB3Q3244PW uses an internal charge pump to elevate gate voltage of pass transistors, enabling flat, low ron across its 2.3–3.6 V VCC range and supporting rail-to-rail signal translation between 0.8 V and 5 V logic levels. Its dual 4-bit architecture allows flexible configuration as either two independent 4-bit switches or one 8-bit switch via separate 1OE and 2OE controls.

Each switch channel provides bidirectional data flow with near-zero propagation delay (0.12–0.2 ns), high-impedance isolation when disabled, and undershoot clamp diodes on all control inputs. The device meets JESD 78 Class II latch-up (>100 mA) and JESD 22 ESD standards (2000-V HBM, 1000-V CDM), ensuring robust operation in mixed-voltage system interfaces.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.5 mm × 4.4 mm, 1.2 mm max height, 0.65 mm pitch, exposed pad not present, 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 SN74CB3Q3244PW, SN74CBTLV3244PWR offers lower cost but sacrifices 5-V I/O tolerance and rail-to-rail performance, while TS3A24159PWR delivers superior ron at the expense of voltage range and power-down safety-making SN74CB3Q3244PW optimal for industrial mixed-voltage bus isolation.

Availability

SN74CB3Q3244PW is available at Aetrix Electronics and suitable for memory interleaving, PCIe sideband isolation, and USB 2.0 dynamic port switching requiring stable component supply across industrial temperature ranges and long-lifecycle programs.

Supply support for SN74CB3Q3244PW 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-speed interface solutions.

The SN74CB3Q3244PW belongs to TI's CB3Q family of high-bandwidth FET bus switches, designed specifically for low-distortion, rail-to-rail signal gating in broadband communications, networking infrastructure, and data-intensive computing systems.

FAQ

What is the maximum signal frequency supported by the SN74CB3Q3244PW?

The SN74CB3Q3244PW supports up to 500 MHz bandwidth due to its low 4 Ω typical ON-state resistance and 3.5 pF OFF-state I/O capacitance. This enables clean signal transmission in high-speed digital applications such as DDR memory control buses and PCIe sideband lines without significant attenuation or phase shift.

Does the SN74CB3Q3244PW support partial-power-down operation?

Yes, the SN74CB3Q3244PW features Ioff circuitry that limits current to 1 µA when VCC = 0 and I/O pins are biased to 0–5.5 V. This protects the device and surrounding circuitry during hot-swap or staggered power sequencing, making it suitable for modular industrial systems requiring safe partial-power-down behavior.

Can the SN74CB3Q3244PW interface between 3.3-V and 5-V logic domains?

Yes, the SN74CB3Q3244PW has 5-V-tolerant I/Os and supports rail-to-rail switching from 0 V to 5.5 V on both A and B ports-even when powered from 3.3-V VCC. This eliminates the need for external level shifters in mixed-voltage applications like legacy peripheral interfacing or USB PHY isolation.

What is the thermal performance of the SN74CB3Q3244PW in its TSSOP-20 package?

The SN74CB3Q3244PW in PW package has a thermal impedance θJA of 83°C/W. At typical ICC of 0.7 mA and worst-case power dissipation, junction temperature rise remains well within −40°C to 85°C operating range under standard PCB layout conditions with adequate copper pour around GND and VCC pins.

How does the charge pump in the SN74CB3Q3244PW improve switching performance?

The internal charge pump in the SN74CB3Q3244PW elevates the gate voltage of the pass transistors, ensuring strong enhancement-mode conduction across the full 2.3–3.6 V VCC range. This delivers flat 4 Ω ron and enables true rail-to-rail signal handling-critical for preserving signal fidelity in high-speed analog and digital signal gating applications.