Texas Instruments SN74CB3Q3345DGVR

Overview

SN74CB3Q3345 from Texas Instruments is an 8-bit FET bus switch optimized for high-bandwidth, low-distortion signal routing in 2.5-V/3.3-V systems. It delivers rail-to-rail switching (0–5 V with 3.3-V V_CC), 4 Ω typical ON-state resistance (r_on), sub-0.2 ns propagation delay, and 5-V-tolerant I/Os - enabling use in memory interleaving, differential signal interface, and bus isolation applications.

For engineers reviewing the SN74CB3Q3345 datasheet, SN74CB3Q3345 pinout, SN74CB3Q3345 application, or SN74CB3Q3345 equivalent, this page provides verified technical context, validated pin functions, real-world application mappings, and confirmed alternative options for high-speed digital and analog signal gating designs.

Technical Context

The SN74CB3Q3345 employs a charge-pump-enhanced FET architecture to maintain flat, low r_on across input voltage range (0–5 V), supporting bidirectional, near-zero-delay data flow between A and B ports. Its dual OE inputs (active-high and active-low) enable flexible enable logic, while I_off circuitry ensures backflow prevention during partial power-down.

Designed for broadband communications and data-intensive computing, it operates over V_CC = 2.3–3.6 V, supports up to 20 MHz OE switching frequency, and features ultra-low OFF-state capacitance (C_io(OFF) = 4 pF typ) to minimize loading and signal distortion on high-speed buses.

Key Specifications

Pinout & Package

SN74CB3Q3345DGVR uses a 20-pin TVSOP (DGV) package - 4.4 mm × 6.2 mm, 0.65 mm pitch, 1.2 mm max height - with exposed thermal pad for enhanced thermal dissipation in dense PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3Q3345, SN74CBT3345PWR trades bandwidth and voltage flexibility for cost in legacy 5-V infrastructure, while SN74LVC1G3157DCKR offers miniaturization at the expense of channel count and isolation robustness - making SN74CB3Q3345 the optimal choice for 8-bit, mixed-voltage, high-fidelity bus switching.

Availability

SN74CB3Q3345 is available at Aetrix Electronics and suitable for memory interleaving, differential signal interface, and bus isolation applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for industrial and telecom equipment.

Supply support for SN74CB3Q3345 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 solutions, with decades of expertise in high-speed interface ICs and signal-integrity-critical components.

The SN74CB3Q3345 belongs to TI's CB3Q family of high-bandwidth FET bus switches, designed specifically for low-distortion, rail-to-rail signal routing in broadband communications, networking, and data-intensive computing systems.

FAQ

What is the maximum operating frequency supported by SN74CB3Q3345 for data signals?

The SN74CB3Q3345 does not specify a maximum data rate in MHz, but its high-bandwidth architecture supports signal frequencies up to 500 MHz as confirmed in TI's application report SCDA008. This performance stems from its 4 Ω r_on, 4 pF C_io(OFF), and sub-0.2 ns propagation delay - enabling clean pass-through of fast edges in DDR, PCIe, and LVDS applications. The 20 MHz limit applies only to OE control switching, not data throughput.

Does SN74CB3Q3345 support partial power-down mode, and how is it implemented?

Yes, SN74CB3Q3345 supports partial power-down mode via its I_off circuitry, which limits reverse current to ≤1 µA when V_CC = 0 and VI/O = 0–5.5 V. This feature prevents damaging backflow from live I/Os into a powered-down device, enabling safe hot-plug operation and independent domain power sequencing - a key requirement in modular server and telecom chassis designs using SN74CB3Q3345.

Can SN74CB3Q3345 operate with a 2.5-V supply, and what performance changes occur?

Yes, SN74CB3Q3345 operates across V_CC = 2.3–3.6 V, including 2.5 V nominal. At 2.5 V, r_on increases slightly to 4.5–9 Ω (vs. 4 Ω at 3.3 V), and rail-to-rail switching supports 0–3.3 V signals. All timing parameters (tpd, ten, tdis) remain within specification, and I_off, C_io(OFF), and 5-V tolerance are fully maintained - making SN74CB3Q3345 suitable for mixed-supply SoC interfaces.

What is the function of the dual OE inputs on SN74CB3Q3345?

SN74CB3Q3345 features two complementary output-enable inputs (OE and OE): the switch conducts bidirectionally when OE is high OR OE is low; it enters high-impedance state only when OE is low AND OE is high. This dual-input logic allows flexible control via single-ended or differential enable sources, simplifies interface with legacy TTL/CMOS drivers, and supports fail-safe default-OFF configurations using pull-up/pull-down resistors - a design advantage unique to SN74CB3Q3345 among TI's bus switches.

Is SN74CB3Q3345 pin-compatible with other members of the CB3Q family, such as SN74CB3Q3245?

No, SN74CB3Q3345 is not pin-compatible with SN74CB3Q3245. While both are 8-bit CB3Q bus switches, SN74CB3Q3245 uses a different pinout: it has a single OE input and places GND at Pin 10 and V_CC at Pin 20 - same as SN74CB3Q3345 - but reassigns A/B port mapping and lacks the second OE terminal. Physical substitution would cause functional failure; board layout must match the exact pin configuration defined for SN74CB3Q3345 in the DGV package drawing.