Texas Instruments SN74CBTD3306CD

Overview

SN74CBTD3306CD from Texas Instruments is a dual 1-bit high-speed FET bus switch with bidirectional data flow, 3 Ω typical ON-state resistance, −2 V undershoot protection on A/B ports, and integrated 5-V-to-3.3-V level shifting via V_CC-series diode. It operates from 4.5 V to 5.5 V and supports USB interface and bus isolation applications.

For engineers reviewing the SN74CBTD3306CD datasheet, SN74CBTD3306CD pinout, SN74CBTD3306CD application, or SN74CBTD3306CD equivalent, key selection criteria include I_off-enabled partial-power-down operation, 0.15 ns propagation delay, 5 pF OFF-state I/O capacitance, and SOIC-8 package compatibility with industrial temperature range (−40°C to 85°C).

Technical Context

The SN74CBTD3306CD implements two independent TTL-compatible FET switches, each controlled by dedicated OE inputs (1OE, 2OE), enabling use as either two 1-bit switches or one 2-bit switch. Its active undershoot-protection circuitry senses −2 V transients at A/B ports and forces the switch into OFF state to prevent erroneous conduction.

Level shifting is achieved via an internal diode in series with V_CC, allowing 5-V inputs to drive 3.3-V outputs without external components. The device supports 0–5-V signaling across seven logic families (0.8 V to 5 V) and features I_off to block backflow current during partial power-down, ensuring isolation when V_CC = 0 V.

Key Specifications

Pinout & Package

SN74CBTD3306CD is housed in an 8-pin SOIC (D) package per JEDEC MS-012AA, 3.91 mm body width, 1.75 mm max height, with gull-wing leads and pin 1 identifier in top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3306CD, SN74CBT3244CD offers higher density but no level shifting, while SN74LVC1G3157DCKR reduces footprint at the cost of bidirectionality, undershoot resilience, and 5-V compatibility-making SN74CBTD3306CD optimal for robust, mixed-voltage, dual-channel gating.

Availability

SN74CBTD3306CD is available at Aetrix Electronics and suitable for USB interface design, memory interleaving architectures, and industrial bus isolation requiring stable component supply across extended temperature ranges.

Supply support for SN74CBTD3306CD 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 logic solutions with over 50 years of innovation in high-reliability interface ICs.

The SN74CBTD3306CD belongs to TI's CBTD family of high-speed FET bus switches, engineered specifically for low-distortion, bidirectional signal gating in mixed-voltage digital systems including computing, communications, and industrial control.

FAQ

What is the maximum undershoot voltage the SN74CBTD3306CD can withstand on its A and B ports?

The SN74CBTD3306CD provides active undershoot protection up to −2 V on both A and B ports, as confirmed in the absolute maximum ratings and undershoot characteristics tables of the SCDS128A datasheet. This protection is implemented via internal sensing circuitry that forces the switch into the OFF state during such events, preventing unintended conduction or latch-up. The SN74CBTD3306CD maintains this rating across its full operating temperature range of −40°C to 85°C.

Does the SN74CBTD3306CD support true bidirectional signal flow without direction control pins?

Yes, the SN74CBTD3306CD supports fully bidirectional data flow between its A and B ports with no direction pin required. Each switch (1A↔1B and 2A↔2B) operates as a passive FET path-current and signal propagate equally in either direction when enabled by the respective OE input. This architecture eliminates timing skew and control logic overhead, making the SN74CBTD3306CD ideal for applications like USB differential pair gating and memory bus multiplexing where signal symmetry is essential.

Can the SN74CBTD3306CD be used for level shifting between 5-V and 3.3-V logic domains?

Yes, the SN74CBTD3306CD integrates a diode in series with V_CC to provide passive 5-V-to-3.3-V level shifting, as explicitly stated in the device description and functional diagram. When a 5-V signal is applied to the A port, the internal diode drops ~0.7 V, resulting in ~3.3-V output at the B port-enabling direct interfacing between legacy 5-V controllers and modern 3.3-V peripherals without external components. This feature is intrinsic to the SN74CBTD3306CD and does not require additional biasing.

What is the typical ON-state resistance (r_on) of the SN74CBTD3306CD and how does it affect signal integrity?

The SN74CBTD3306CD has a typical ON-state resistance of 3 Ω at V_CC = 4.5 V, as specified in the electrical characteristics table. This low r_on minimizes voltage drop and power dissipation during signal transmission, preserving signal amplitude and edge rate-especially critical for high-speed digital signals up to 128 mA. Combined with 5 pF OFF-state capacitance, the SN74CBTD3306CD ensures minimal loading and distortion in applications such as memory interleaving and USB interface gating.

How does the I_off feature of the SN74CBTD3306CD enhance system reliability during partial power-down?

When V_CC = 0 V, the SN74CBTD3306CD limits I_off to 10 µA, effectively blocking reverse current flow between powered and unpowered sections of a system. This prevents backfeeding, voltage contention, and potential damage during hot-swap or staged power sequencing-key for industrial backplanes and modular instrumentation. The I_off specification is validated per JESD 78 Class II latch-up testing, confirming robustness in real-world partial-power-down scenarios involving the SN74CBTD3306CD.