Texas Instruments SN74CBT3345CDW

Overview

SN74CBT3345CDW from Texas Instruments is an 8-bit bidirectional FET bus switch with dual OE control inputs, 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 - deployed in USB interface signal gating and memory interleaving applications.

For engineers reviewing the SN74CBT3345CDW datasheet, SN74CBT3345CDW pinout, SN74CBT3345CDW application, or SN74CBT3345CDW equivalent, key selection criteria include Ioff partial-power-down support, 0–5.5 V data I/O voltage compatibility, dual active-high/active-low enable logic, and SOIC-20 package thermal performance (θJA = 58°C/W).

Technical Context

The SN74CBT3345CDW implements TTL-compatible FET-based switching with independent high-impedance control via complementary OE and OE inputs: OE high *or* OE low enables bidirectional conduction between A and B ports; both OE low and OE high disables the switch. Its undershoot-protection circuitry actively clamps A/B port voltages down to −2 V while maintaining OFF-state isolation.

Designed for mixed-voltage system interfacing, the device supports 0.8 V to 5 V signaling levels on data I/Os without level translation, while control inputs accept TTL or 3.3/5 V CMOS logic. Ioff functionality prevents backflow current during partial power-down, ensuring safe isolation when VCC = 0 V.

Key Specifications

Pinout & Package

SN74CBT3345CDW uses a 20-pin SOIC (DW) package with 7.5 mm body width, 2.65 mm max height, and 1.27 mm lead pitch. Pin 1 is located at top-left corner with index area marking; leads are gull-wing, NIPDAU-finished, MSL Level-1 rated.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3345CDW, SN74CBTD3305PWR trades undershoot protection and 5 V operation for lower cost in 3.3 V-only systems, while PI3CH400LE offers wider VCC range but requires duplication and lacks complementary enable logic - making SN74CBT3345CDW optimal for robust, single-package 5 V mixed-signal bus isolation.

Availability

SN74CBT3345CDW is available at Aetrix Electronics and suitable for USB interface design, memory subsystem routing, and industrial bus isolation requiring stable component supply across extended temperature ranges (−40°C to 85°C).

Supply support for SN74CBT3345CDW 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 SN74CBT3345CDW belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital systems where timing integrity and power sequencing safety are critical.

FAQ

What is the maximum undershoot voltage the SN74CBT3345CDW can tolerate on its A and B ports?

The SN74CBT3345CDW provides active undershoot protection up to −2 V on both A and B ports, as verified in the SCDS129A datasheet undershoot characteristics table. This capability is implemented via internal clamp circuitry that maintains OFF-state isolation even during transient negative excursions, eliminating the need for external protection diodes in the SN74CBT3345CDW signal path.

Does the SN74CBT3345CDW support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3345CDW supports partial-power-down operation via its Ioff feature. When VCC = 0 V, the device limits backflow current to 10 µA maximum, preventing damaging current from flowing through powered-down sections of the system. This behavior is intrinsic to the SN74CBT3345CDW's FET architecture and is specified across the full −40°C to 85°C temperature range.

What are the valid logic voltage levels for controlling the OE and OE inputs of the SN74CBT3345CDW?

The OE and OE inputs of the SN74CBT3345CDW accept TTL or 5 V/3.3 V CMOS logic levels: VIH ≥ 2 V (high), VIL ≤ 0.8 V (low). The SN74CBT3345CDW does not require level-shifting drivers - standard microcontroller GPIO or FPGA outputs operating at 3.3 V or 5 V can directly drive these controls per the recommended operating conditions table.

Can the SN74CBT3345CDW be used to route analog signals such as audio or sensor outputs?

Yes, the SN74CBT3345CDW is qualified for analog applications including audio signal gating, as confirmed by its low ON-state resistance (3 Ω typical), low OFF-capacitance (5.5 pF), and flat frequency response. The SN74CBT3345CDW has been applied in DAC output switching and low-distortion signal paths where preservation of DC accuracy and bandwidth up to 10 MHz is required.

What is the thermal performance of the SN74CBT3345CDW in its SOIC-20 (DW) package?

The SN74CBT3345CDW in the SOIC-20 (DW) package has a junction-to-ambient thermal resistance (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 at full load across the −40°C to 85°C ambient range without forced airflow or heatsinking.