Texas Instruments SN74CBTD3306PW

Overview

SN74CBTD3306PW from Texas Instruments is a dual FET bus switch with integrated level-shifting capability, designed for bidirectional signal routing between 5-V and 3.3-V logic domains. It features 5-Ω on-state resistance, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and operates across −40°C to 85°C. Used in mixed-voltage memory/data bus interfacing where voltage translation and low-insertion-loss switching are required.

For engineers reviewing the SN74CBTD3306PW datasheet, SN74CBTD3306PW pinout, SN74CBTD3306PW application, or SN74CBTD3306PW equivalent, key selection criteria include on-resistance matching, level-shifting directionality (5-V input → 3.3-V output), OE-controlled isolation timing (tdis = 1–4.7 ns), and TSSOP-8 thermal performance (θJA = 149°C/W).

Technical Context

The SN74CBTD3306PW implements two independent NMOS transmission-gate switches, each controlled by a dedicated OE input. Its internal VCC-clamp diode enables passive level shifting from 5-V inputs to 3.3-V outputs without external components. Switch operation is bidirectional, with no internal directionality or data latching.

It functions within a 4.5–5.5-V supply range and supports fast switching (tpd = 0.25 ns typical) into 50-pF loads. Control inputs tolerate TTL thresholds and must be actively driven to VCC or GND-floating inputs risk undefined behavior per TI application note SCBA004.

Key Specifications

Pinout & Package

TSSOP-8 (PW) package: 3.0 mm × 4.4 mm body, 0.65 mm lead pitch, 1.2 mm max height, gull-wing leads, JEDEC MO-153 compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual bus switch with level-shifting applications.

Compared with SN74CBTD3306PW, SN74CBT3306PW removes integrated level shifting but lowers cost and power, while SN74LVC1T45DCKR offers greater voltage adaptability at the expense of channel count, pin compatibility, and control architecture.

Availability

SN74CBTD3306PW is available at Aetrix Electronics and suitable for industrial I/O modules, legacy system upgrades, and mixed-voltage memory interfaces requiring stable component supply and long-term obsolescence management.

Supply support for SN74CBTD3306PW 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and communications reach.

The SN74CBTD3306PW belongs to TI's 74CBT/74CBTD logic family, engineered specifically for high-speed, low-distortion bus switching in mixed-voltage digital systems - emphasizing signal fidelity, level translation, and robust ESD tolerance.

FAQ

What is the primary function of the SN74CBTD3306PW in a mixed-voltage system?

The SN74CBTD3306PW serves as a dual bidirectional bus switch that enables seamless 5-V-to-3.3-V level shifting without external components. Its integrated VCC-referenced clamp diode allows signals applied to the A port (5-V domain) to appear translated at the B port (3.3-V domain), making SN74CBTD3306PW ideal for interfacing legacy 5-V controllers with modern 3.3-V peripherals.

Can the SN74CBTD3306PW operate with a 3.3-V supply voltage?

No - the SN74CBTD3306PW requires a 4.5–5.5-V VCC supply to enable its internal level-shifting diode and guarantee specified on-resistance and timing performance. Operating below 4.5 V violates recommended conditions and disables the intended 5-V-to-3.3-V translation function; SN74CBTD3306PW is not rated for 3.3-V VCC operation.

How does the SN74CBTD3306PW handle floating control inputs?

SN74CBTD3306PW requires all OE inputs to be actively driven to VCC or GND; floating OE pins cause undefined switch states and potential shoot-through or leakage. TI application report SCBA004 explicitly mandates termination - leaving OE unconnected risks unreliable channel disablement and increased ICC. This requirement applies directly to SN74CBTD3306PW in all operating conditions.

Is the SN74CBTD3306PW pin-compatible with the SN74CBT3306PW?

Yes - SN74CBTD3306PW and SN74CBT3306PW share identical TSSOP-8 pinout, package dimensions, and terminal assignments. However, SN74CBTD3306PW includes an internal level-shifting diode absent in SN74CBT3306PW, meaning the latter cannot perform native 5-V-to-3.3-V translation without external circuitry. The pin compatibility enables mechanical replacement but not functional equivalence.

What thermal considerations apply to the SN74CBTD3306PW in continuous operation?

With θJA = 149°C/W in the TSSOP-8 package, SN74CBTD3306PW requires careful thermal design: at 100 mA per channel and 5.5-V VCC, power dissipation reaches ~55 mW per switch, raising junction temperature significantly above ambient. Layout must include ≥1 cm² of 2-oz copper connected to GND/VCC pins, and SN74CBTD3306PW should avoid placement near other heat sources to prevent exceeding 125°C junction limit.