Texas Instruments SN74CB3Q3244DGVR

Overview

SN74CB3Q3244 from Texas Instruments is a high-bandwidth 8-bit FET bus switch with dual 4-bit configurable operation, 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. It enables bidirectional signal routing in memory interleaving and bus isolation applications with near-zero propagation delay (0.12 ns typical) and 3.5 pF typical OFF-state I/O capacitance.

For engineers reviewing the SN74CB3Q3244 datasheet, SN74CB3Q3244 pinout, SN74CB3Q3244 application, or SN74CB3Q3244 equivalent, key selection criteria include partial-power-down support via Ioff, 20 MHz max OE switching frequency, flat ron over voltage range, and TVSOP-20 (DGV) package compatibility with high-density PCB layouts.

Technical Context

The SN74CB3Q3244 implements a charge-pump-enhanced FET switch architecture to maintain low, flat ON-state resistance across 0–5 V signal swing and 2.3–3.6 V VCC. Its dual independent 4-bit sections (1OE/2OE control) support flexible 8-bit or split-bus configurations with true bidirectional data flow and no direction pin.

Each switch channel features undershoot clamp diodes on control inputs, supports TTL/5-V/3.3-V CMOS drive compatibility, and guarantees isolation during power-up/down via Ioff circuitry that limits backflow current to ≤1 µA when VCC = 0 V.

Key Specifications

Pinout & Package

SN74CB3Q3244 is packaged in a 20-pin TVSOP (DGV) with 0.65 mm pitch, 4.3 mm × 3.6 mm body size, and 1.2 mm max height - optimized for space-constrained, high-pin-count PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3Q3244, SN74CBT3244DBQR trades 5-V tolerance and flat ron for lower cost in 5 V-only designs, while SN74LVC2G66DCUR offers voltage flexibility but lacks the integrated dual-bus architecture and Ioff protection required for robust system-level isolation.

Availability

SN74CB3Q3244 is available at Aetrix Electronics and suitable for memory interleaving, bus isolation, and differential signal interface applications requiring stable component supply, long-term lifecycle support, and consistent TVSOP-20 (DGV) packaging.

Supply support for SN74CB3Q3244 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 components.

The SN74CB3Q3244 belongs to TI's CB3Q family of high-bandwidth FET bus switches, engineered specifically for broadband communications, networking infrastructure, and data-intensive computing systems demanding minimal propagation delay and rail-to-rail signal integrity.

FAQ

What is the maximum signal frequency supported by the SN74CB3Q3244?

The SN74CB3Q3244 supports high-bandwidth data paths up to 500 MHz, as confirmed by TI's characterization of the CB3Q family. This performance is enabled by its low 4 Ω typical ON-state resistance and 3.5 pF typical OFF-state I/O capacitance, which jointly minimize RC delay and signal distortion. Actual usable frequency depends on PCB layout, load capacitance, and termination - design validation at target data rates is recommended using the SN74CB3Q3244's published tpd and fOE specifications.

Does the SN74CB3Q3244 support partial-power-down operation?

Yes, the SN74CB3Q3244 fully supports partial-power-down operation via its Ioff circuitry, which limits reverse current to ≤1 µA when VCC = 0 V and VI/O = 0–5.5 V. This feature prevents damaging backflow through the device during hot-swap or mixed-power-domain scenarios. The SN74CB3Q3244 maintains high-impedance isolation between A and B ports under these conditions, making it suitable for live-backplane and modular system architectures where subsystems power up/down independently.

Can the SN74CB3Q3244 interface between 1.8 V and 5 V logic domains?

Yes, the SN74CB3Q3244 supports 0–5 V signaling on its A/B I/O ports while operating from a 2.3–3.6 V VCC supply, enabling direct level-shifting-free interfacing between 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains. Its 5-V-tolerant I/Os accept inputs up to 5.5 V regardless of VCC level, and rail-to-rail switching ensures full-swing signal transmission. No external level translators are needed - the SN74CB3Q3244 handles bidirectional voltage translation inherently.

What is the purpose of the charge pump in the SN74CB3Q3244?

The charge pump in the SN74CB3Q3244 elevates the gate voltage of the internal FET pass transistors to ensure low and flat ON-state resistance (ron ≈ 4 Ω typical) across the entire 0–5 V input voltage range. Without this circuit, ron would rise significantly at low VI/O levels, degrading signal integrity and timing. The charge pump enables consistent ron performance regardless of signal swing - a key enabler for the SN74CB3Q3244's 500 MHz bandwidth and rail-to-rail switching capability.

How does the SN74CB3Q3244 handle power-up sequencing?

To ensure high-impedance state during power-up, the SN74CB3Q3244 requires OE pins (1OE, 2OE) to be held high via pullup resistors to VCC - minimum value determined by driver sink capability. This prevents unintended switch activation before VCC stabilizes. The device's Ioff and undershoot clamp diodes further enhance robustness during uncontrolled ramp-up. TI recommends referencing SCBA004 for best practices; proper OE biasing is essential for reliable SN74CB3Q3244 operation in systems with asynchronous power rails.