Texas Instruments SN74CBT3306CPW

Overview

SN74CBT3306CPW from Texas Instruments is a dual 1-bit high-speed FET bus switch IC with bidirectional signal routing, 3 Ω typical ON-state resistance (ron), −2 V undershoot protection on A/B ports, and 5 pF typical OFF-state I/O capacitance. It operates from 4 V to 5.5 V and supports mixed-voltage signaling (0.8 V to 5 V) in USB interface and bus isolation applications.

For engineers reviewing the SN74CBT3306CPW datasheet, SN74CBT3306CPW pinout, SN74CBT3306CPW application, or SN74CBT3306CPW equivalent, key selection criteria include undershoot tolerance, propagation delay (<0.24 ns at 4 V), partial-power-down Ioff support, and TSSOP-8 package compatibility with space-constrained digital interconnect designs.

Technical Context

The SN74CBT3306CPW implements two independent TTL-compatible FET switches, each controlled by dedicated OE inputs (1OE, 2OE). Its active undershoot-protection circuitry senses sub-0 V transients up to −2 V on A/B ports and forces the switch into a guaranteed OFF state, preventing false conduction during signal undershoot events.

Each switch provides near-zero propagation delay via low-impedance FET conduction paths and supports bidirectional data flow with no direction control required. The device features Ioff functionality that blocks current backflow during partial power-down, ensuring isolation when VCC = 0 V while I/O pins remain at 0–5.5 V.

Key Specifications

Pinout & Package

TSSOP-8 package (PW), 3.0 mm × 4.4 mm body, 0.65 mm lead pitch, 1.2 mm max height, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3306CPW, SN74CBTD3306CPW adds bus-hold but increases quiescent current, while 74LVC1G3157GW offers smaller footprint and lower cost for single-channel use but lacks undershoot protection and dual-switch integration - making SN74CBT3306CPW optimal for robust, dual-path, hot-plug-ready digital interconnects.

Availability

SN74CBT3306CPW is available at Aetrix Electronics and suitable for USB interface isolation, memory bus gating, low-distortion analog routing, and legacy-to-modern logic interfacing requiring stable component supply and long-term industrial availability.

Supply support for SN74CBT3306CPW 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 silicon design.

The SN74CBT3306CPW belongs to TI's CBT (Crossbar Bus Technology) family of high-speed FET bus switches, engineered for minimal propagation delay and robust signal integrity in digital interconnect, hot-swap, and mixed-voltage system applications.

FAQ

What is the maximum undershoot voltage the SN74CBT3306CPW can withstand on its A and B ports?

The SN74CBT3306CPW guarantees OFF-state operation during undershoot events down to −2 V on both A and B ports, as verified per test conditions in the SCDS127A datasheet. This protection is implemented via internal active clamping circuitry and does not require external components. The −2 V rating applies across the full operating temperature range (−40°C to 85°C) and is independent of VCC level within 4 V–5.5 V.

Does the SN74CBT3306CPW support bidirectional signal flow without direction control pins?

Yes, the SN74CBT3306CPW supports fully bidirectional signal flow on both 1A↔1B and 2A↔2B paths without any direction control pins. Each switch operates as a passive FET bridge: when its respective OE input is low, the A and B terminals are conductively linked with 3 Ω typical ron, allowing data to pass in either direction. No internal logic or timing asymmetry is introduced, making it ideal for protocols like I²C or USB where signal direction changes dynamically.

Can the SN74CBT3306CPW be used in partial-power-down systems where VCC is disconnected?

Yes, the SN74CBT3306CPW includes Ioff functionality that limits current to 10 µA maximum when VCC = 0 V, even with I/O voltages ranging from 0 V to 5.5 V. This ensures safe isolation during power sequencing - for example, when a microcontroller powers down before its peripherals - and prevents damaging back-current flow. The feature is specified over the full temperature range and requires no external circuitry to activate.

What is the typical ON-state resistance (ron) of the SN74CBT3306CPW and how does it affect signal integrity?

The SN74CBT3306CPW has a typical ON-state resistance of 3 Ω at VCC = 4.5 V and IO = 30 mA, with a maximum of 6 Ω across process/voltage/temperature. This low ron minimizes voltage drop across the switch (e.g., <192 mV at 64 mA), preserving logic high/low margins and reducing signal distortion. Combined with 12.5 pF Cio(ON), it maintains fast edge rates and low insertion loss in high-speed digital paths such as memory address buses or USB data lanes.

Is the SN74CBT3306CPW compatible with 1.8-V and 3.3-V logic families while powered from a 5-V supply?

Yes, the SN74CBT3306CPW supports 0–5.5 V signaling on its A/B I/O ports regardless of VCC (4–5.5 V), enabling seamless interfacing between 1.8-V, 2.5-V, 3.3-V, and 5-V logic families. Control inputs (OE) accept TTL- or CMOS-level signals and are compatible with 3.3-V or 5-V drivers. This eliminates external level shifters in mixed-voltage systems - for instance, connecting a 1.8-V FPGA core to a 5-V EEPROM using a single SN74CBT3306CPW.