Texas Instruments SN74CBT3345CPW

Overview

SN74CBT3345CPW from Texas Instruments is an 8-bit bidirectional FET bus switch with TTL-compatible control inputs, near-zero propagation delay (0.15 ns typical at 5 V), 3 Ω typical ON-state resistance, and undershoot protection to −2 V on both A and B ports. It enables low-distortion signal gating in USB interfaces and memory interleaving applications operating across 0–5-V signaling levels.

For engineers reviewing the SN74CBT3345CPW datasheet, SN74CBT3345CPW pinout, SN74CBT3345CPW application, or SN74CBT3345CPW equivalent, key selection criteria include Ioff-enabled partial-power-down support, 5.5-pF typical OFF-state I/O capacitance, dual OE control logic, and TSSOP-20 package compatibility with industrial temperature range (−40°C to 85°C).

Technical Context

The SN74CBT3345CPW implements a dual-enable 8-bit FET switch architecture where OE high *or* OE low activates bidirectional conduction between corresponding A1–A8 and B1–B8 terminals. Its active undershoot-protection circuitry monitors port voltage transients and forces OFF-state isolation when A/B pins drop below −2 V, preventing latch-up during hot-plug events.

It supports mixed-voltage system interfacing via 0–5-V data I/O tolerance and TTL/3.3-V/5-V CMOS-compatible control inputs. The Ioff feature guarantees no backflow current during partial power-down, and the device maintains high-impedance isolation when unpowered-critical for bus isolation in multi-rail embedded systems.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.5 mm × 4.4 mm footprint, 0.65 mm lead pitch, 1.2 mm max height, RoHS-compliant NIPDAU finish, MSL Level-1 (260°C peak reflow, unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit bus switch applications.

Compared with SN74CBT3345CPW, SN74CBTD3305PW trades undershoot protection and 5-V operation for lower cost in 3.3-V-only designs, while 74LVC245APW replaces bidirectional simplicity with direction-pin overhead and lacks critical reliability features for hot-plug or multi-rail systems.

Availability

SN74CBT3345CPW is available at Aetrix Electronics and suitable for USB interface design, memory interleaving, bus isolation, and low-distortion signal gating requiring stable component supply across industrial temperature ranges and long-lifecycle production programs.

Supply support for SN74CBT3345CPW 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 logic and interface solutions.

The SN74CBT3345CPW belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for ultra-low-latency, low-distortion signal routing in mixed-voltage digital systems-particularly targeting USB, memory, and industrial bus isolation applications.

FAQ

What is the maximum undershoot voltage the SN74CBT3345CPW can withstand on its A and B ports?

The SN74CBT3345CPW provides active undershoot protection up to −2 V on both A and B ports, as verified in the SCDS129A datasheet under "Undershoot Characteristics." This ensures the switch remains reliably OFF during negative transients, preventing unintended conduction in hot-plug or cable-disconnect scenarios. The SN74CBT3345CPW achieves this via integrated sensing circuitry that overrides the control logic when port voltage drops below −2 V.

Does the SN74CBT3345CPW support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3345CPW fully supports partial-power-down operation via its Ioff feature. When VCC = 0 V, the device limits off-state current to 10 µA maximum, preventing damaging back-current flow through the I/O ports. This behavior is guaranteed across the full −40°C to 85°C operating range and is validated per JESD 78 Class II latch-up testing. The SN74CBT3345CPW maintains high-impedance isolation between A and B ports even when unpowered.

What is the typical ON-state resistance (ron) of the SN74CBT3345CPW, and how does it affect signal integrity?

The SN74CBT3345CPW has a typical ON-state resistance of 3 Ω at VCC = 4.5 V and IO = 30 mA, as specified in the electrical characteristics table of the SCDS129A datasheet. This low ron minimizes voltage drop and signal attenuation across the switch, preserving logic high/low margins and reducing timing skew in parallel bus applications. For example, at 100 mA channel current, the drop is only 300 mV-well within noise margins for 5-V TTL and 3.3-V CMOS systems. The SN74CBT3345CPW maintains consistent ron across its full 0–5.5-V I/O voltage range.

Can the SN74CBT3345CPW interface between different logic voltage levels, such as 1.8-V and 5-V domains?

Yes, the SN74CBT3345CPW supports 0–5.5-V signaling on its A and B I/O ports and accepts TTL or 5-V/3.3-V CMOS control inputs-enabling direct bridging between 0.8-V, 1.2-V, 1.5-V, 1.8-V, 2.5-V, 3.3-V, and 5-V logic families without external level shifters. Its voltage-tolerant architecture allows the SN74CBT3345CPW to pass signals bidirectionally regardless of relative domain voltages, provided VCC is supplied within 4–5.5 V. This capability is explicitly confirmed in the "Data I/Os Support 0 to 5-V Signaling Levels" feature list.

What package type and thermal characteristics apply to the SN74CBT3345CPW?

The SN74CBT3345CPW uses the TSSOP-20 (PW) package: 6.5 mm × 4.4 mm body, 0.65 mm lead pitch, 1.2 mm max height, with NIPDAU lead finish and MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH). Its thermal impedance is 83°C/W (θJA), as documented in the absolute maximum ratings table. The SN74CBT3345CPW's compact TSSOP footprint supports high-density PCB layouts while maintaining adequate thermal performance for typical logic-level power dissipation (<1 mW static).