Texas Instruments SN74CBT3345CDWR

Overview

SN74CBT3345CDWR from Texas Instruments is an 8-bit bidirectional FET bus switch IC with dual OE control, 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), and −2 V undershoot protection on A/B ports. It operates from 4 V to 5.5 V and supports 0–5 V signaling across mixed-voltage systems including USB interface and memory interleaving.

For engineers reviewing the SN74CBT3345CDWR datasheet, SN74CBT3345CDWR pinout, SN74CBT3345CDWR application, or SN74CBT3345CDWR equivalent, key selection criteria include Ioff-enabled partial-power-down capability, 5.5 pF OFF-state I/O capacitance for low signal distortion, TTL/CMOS-compatible control inputs, and SOIC-20 package compatibility with industrial bus isolation designs.

Technical Context

The SN74CBT3345CDWR implements a dual-enable 8-bit analog/digital bus switch architecture with independent high-impedance control: OE high *or* OE low enables bidirectional conduction between A1–A8 and B1–B8; both OE low and OE high disable the switch. Its FET-based topology delivers rail-to-rail signal pass-through without level translation.

Undershoot protection circuitry actively monitors A/B port voltages and forces the switch into OFF state during −2 V transients, preventing latch-up or damage in hot-swap or noisy bus environments. The device meets JESD 78 Class II latch-up (>100 mA) and JESD 22 HBM (2000 V) / CDM (1000 V) ESD specifications.

Key Specifications

Pinout & Package

SN74CBT3345CDWR uses a 20-pin SOIC (DW) package with 1.27 mm pitch, 12.8 mm × 7.5 mm body, and 2.65 mm max height per JEDEC MS-013. Pin 1 is located at top-left corner with notch marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3345CDWR, SN74CBTD3305PWR offers greater channel count but sacrifices undershoot resilience, while 74LVC1G3157GW provides compact SPDT switching at lower voltage-neither matches the SN74CBT3345CDWR's combination of 8-bit bidirectionality, −2 V protection, and 4–5.5 V operation.

Availability

SN74CBT3345CDWR is available at Aetrix Electronics and suitable for USB interface design, memory interleaving architectures, and industrial bus isolation requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74CBT3345CDWR 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 electronic components.

The SN74CBT3345CDWR belongs to TI's CBT (CrossBar Technology) bus switch family, engineered for high-speed, low-distortion signal routing in mixed-voltage computing and communications infrastructure.

FAQ

What is the maximum undershoot voltage the SN74CBT3345CDWR can withstand on its A and B ports?

The SN74CBT3345CDWR provides active undershoot protection up to −2 V on both A and B ports, as verified by test conditions in the official datasheet (SCDS129A). This feature ensures the switch remains in the OFF state during transient negative excursions, preventing latch-up or damage without requiring external clamp diodes. The SN74CBT3345CDWR achieves this via integrated sensing circuitry that detects sub-ground events and forces isolation.

Does the SN74CBT3345CDWR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3345CDWR supports partial-power-down operation through its Ioff feature, which limits leakage current to 10 µA when VCC = 0 V. This prevents damaging backflow current from live I/O lines into a powered-down device, ensuring safe isolation in modular systems. The SN74CBT3345CDWR maintains high-impedance between A and B ports during power-off states, making it suitable for hot-swap and power-gated subsystems.

What are the recommended pull-up/pull-down resistors for OE and OE pins during power sequencing?

To ensure high-impedance state during power-up or power-down, OE should be tied to VCC via a pull-up resistor and OE to GND via a pulldown resistor. The minimum resistor value depends on the driver's current-sinking/sourcing capability, as specified in the SN74CBT3345CDWR datasheet. Typical values range from 1 kΩ to 10 kΩ; lower values improve noise immunity but increase static current. The SN74CBT3345CDWR's dual-OE architecture requires both controls to be actively managed for deterministic behavior.

Can the SN74CBT3345CDWR interface between 1.8 V and 5 V logic domains without level shifters?

Yes, the SN74CBT3345CDWR supports 0–5 V signaling on its A and B data I/Os, enabling direct interfacing between 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains. Its FET-switch architecture passes signals without level translation, preserving voltage swing and timing. Control inputs accept TTL or 5 V/3.3 V CMOS levels, and the SN74CBT3345CDWR's VCC range (4–5.5 V) ensures compatibility with standard 5 V supply rails.

What is the thermal performance of the SN74CBT3345CDWR in its SOIC (DW) package?

The SN74CBT3345CDWR in the SOIC (DW) package has a junction-to-ambient thermal impedance (θJA) of 58°C/W, as documented in the absolute maximum ratings table. This value assumes standard JEDEC 2-layer board conditions and enables reliable operation up to 85°C ambient when power dissipation remains within limits. The SN74CBT3345CDWR's ultra-low ICC (3 µA max) and low ron minimize self-heating, making thermal derating rarely necessary in typical bus-switching applications.