Texas Instruments SN74CBT3305CDGKR

Overview

SN74CBT3305CDGKR from Texas Instruments is a dual 1-bit FET bus switch IC designed for high-speed bidirectional signal gating in 4 V–5.5 V systems. It features 3 Ω typical ON-state resistance, –2 V undershoot protection on both A and B ports, and supports 0–5 V signaling levels across mixed-voltage interfaces. Used in USB interface isolation and low-distortion analog/digital signal routing.

For engineers reviewing the SN74CBT3305CDGKR datasheet, SN74CBT3305CDGKR pinout, SN74CBT3305CDGKR application, or SN74CBT3305CDGKR equivalent, key selection criteria include Ioff partial-power-down support, 5 pF OFF-state I/O capacitance, TTL/CMOS-compatible control inputs, and VSSOP-8 package compatibility with space-constrained PCB layouts.

Technical Context

The SN74CBT3305CDGKR implements two independent FET-based transmission gates, each controlled by dedicated OE inputs (1OE, 2OE), enabling per-channel enable/disable without affecting the other. Its active undershoot-protection circuitry monitors A/B port voltages and forces OFF-state isolation when transient undershoot reaches –2 V.

It operates in partial-power-down mode via Ioff (≤10 µA at VCC = 0), preventing backflow current during system power sequencing. The device supports bidirectional signal flow with near-zero propagation delay (0.24 ns typical at VCC = 5 V) and maintains high-impedance isolation when OE is low.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: 2.3 mm × 2.0 mm body, 0.5 mm pitch, 1.2 mm max height, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3305CDGKR, SN74CBTD3305CDGKR offers lower ron but sacrifices 5 V operation and undershoot protection, while 74LVC1G3157GW,125 provides broader VCC range but requires dual placement and adds layout complexity without native Ioff or transient hardening.

Availability

SN74CBT3305CDGKR is available at Aetrix Electronics and suitable for USB interface isolation, bus signal gating, and mixed-voltage domain bridging requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74CBT3305CDGKR 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 solutions, with over 90 years of innovation in high-reliability components.

The SN74CBT3305CDGKR belongs to TI's CBT (Crossbar Bus Technology) family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital systems and interface isolation applications.

FAQ

What is the maximum undershoot voltage the SN74CBT3305CDGKR can tolerate on its A and B ports?

The SN74CBT3305CDGKR provides active undershoot protection up to –2 V on both A and B ports. This is verified per test conditions in the datasheet (VCC = 5.5 V, switch OFF, VIN = VCC or GND), where VOUTU is specified at minimum 2 V. The protection circuit senses negative transients and forces the switch into a guaranteed OFF state to prevent unintended conduction or latch-up.

Does the SN74CBT3305CDGKR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3305CDGKR supports partial-power-down via its Ioff feature. When VCC = 0 V and VI/O = 0–5.5 V, Ioff is guaranteed ≤10 µA, preventing damaging backflow current through the switch terminals. This enables safe hot-plug operation and isolation during power sequencing in multi-rail systems, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables.

What is the typical ON-state resistance (ron) of the SN74CBT3305CDGKR, and under what conditions is it measured?

The typical ON-state resistance (ron) of the SN74CBT3305CDGKR is 3 Ω, measured at VCC = 4.5 V, IO = 30 mA, and VI = 0 V. This value is specified in the Electrical Characteristics table and reflects the voltage drop between A and B terminals under defined current flow, confirming minimal insertion loss in high-speed signal paths.

Can the SN74CBT3305CDGKR interface between 1.8 V and 5 V logic domains without external level shifters?

Yes, the SN74CBT3305CDGKR supports 0–5 V signaling on its A and B I/O ports regardless of VCC (4–5.5 V), enabling direct connection between 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains. This is explicitly stated in the datasheet: "Data I/Os Support 0- to 5-V Signaling Levels (0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, 5 V)." No external biasing or level translation is required.

What package type and dimensions does the SN74CBT3305CDGKR use, and is it RoHS-compliant?

The SN74CBT3305CDGKR uses the VSSOP-8 (DGK) package: 2.3 mm × 2.0 mm body, 0.5 mm lead pitch, 1.2 mm max height. It is RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating. Package drawings and thermal data are documented in TI's SCDS125B datasheet and Package Option Addendum, confirming full compliance with JEDEC MO-153 standards.