Texas Instruments SN74CBT3305CDR

Overview

SN74CBT3305CDR from Texas Instruments is a dual 1-bit FET bus switch IC designed for high-speed bidirectional signal routing in 4 V–5.5 V systems. It features 3 Ω typical ON-state resistance, <0.24 ns propagation delay, –2 V undershoot protection on A/B ports, and I_off support for partial-power-down operation. Used in USB interface isolation and low-distortion analog/digital signal gating.

For engineers reviewing the SN74CBT3305CDR datasheet, SN74CBT3305CDR pinout, SN74CBT3305CDR application, or SN74CBT3305CDR equivalent, key selection criteria include undershoot tolerance, bidirectional low-R_on switching, I_off-enabled power sequencing, and SOIC-8 compatibility with TTL/CMOS control inputs.

Technical Context

The SN74CBT3305CDR implements two independent FET-based transmission gates controlled by separate OE inputs (1OE, 2OE), enabling configurable 1-bit or combined 2-bit bus switching. Each switch supports bidirectional signal flow with near-zero propagation delay and maintains high-impedance isolation when disabled.

Its active undershoot-protection circuitry monitors A/B port voltages down to –2 V and forces OFF-state retention during negative transients. The device meets JESD 78 Class II latch-up immunity (>100 mA) and JESD 22 ESD ratings (2000-V HBM, 1000-V CDM).

Key Specifications

Pinout & Package

SN74CBT3305CDR is packaged in an 8-pin SOIC (D) package with 1.27 mm pitch, 3.91 mm body width, and 1.75 mm max height - compatible with standard surface-mount assembly and IPC-7351 land patterns.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3305CDR, SN74CBTD3305CDR adds 5-V-tolerant control inputs at the cost of slightly higher r_on, while SN74LVC1G3157DCKR trades dual-channel integration and undershoot protection for smaller footprint and wider V_CC range.

Availability

SN74CBT3305CDR is available at Aetrix Electronics and suitable for USB interface isolation, hot-swap backplane gating, and low-distortion analog signal routing requiring stable component supply across industrial and consumer production programs.

Supply support for SN74CBT3305CDR 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 decades of expertise in high-speed interface and power-efficient logic ICs.

The SN74CBT3305CDR belongs to TI's CBT (Crossbar Bus Transceiver) logic family, engineered for low-latency, low-distortion signal switching in mixed-voltage digital and analog systems.

FAQ

What is the maximum undershoot voltage the SN74CBT3305CDR can tolerate on its A/B ports?

The SN74CBT3305CDR provides active undershoot protection down to –2 V on both A and B ports, verified per test conditions in the SCDS125B datasheet. This ensures the switch remains reliably OFF during negative transients, preventing unintended conduction or latch-up in hot-plug scenarios. The protection circuitry is internal and requires no external components.

Does the SN74CBT3305CDR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3305CDR supports partial-power-down via its I_off feature: when V_CC = 0 V, leakage current is limited to 10 µA max, blocking damaging back-current flow between powered and unpowered sections of a bus. This is achieved through internal FET biasing and is specified over –40°C to 85°C, making SN74CBT3305CDR suitable for modular power architectures.

What is the typical ON-state resistance of the SN74CBT3305CDR, and how does it affect signal integrity?

The SN74CBT3305CDR has a typical ON-state resistance (r_on) of 3 Ω at V_CC = 4.5 V and I_O = 30 mA. This low value minimizes voltage drop (<90 mV at 30 mA) and preserves rise/fall times in high-speed digital paths, while also reducing harmonic distortion in analog applications such as audio routing. Measured per JEDEC-standard voltage-drop methodology.

Can the SN74CBT3305CDR be used with 3.3-V control signals while operating from a 5-V supply?

Yes - the SN74CBT3305CDR accepts TTL- and CMOS-compatible control inputs: V_IL ≤ 0.8 V and V_IH ≥ 2 V over 4–5.5 V V_CC. A 3.3-V logic high (≥2.4 V) fully satisfies V_IH, and its inputs draw only ±1 µA, eliminating need for pull-up resistors. This allows seamless interfacing between 3.3-V microcontrollers and 5-V bus domains using SN74CBT3305CDR.

Is the SN74CBT3305CDR pin-compatible with other devices in the SN74CBT3305x series?

Yes - SN74CBT3305CDR shares identical pinout and functionality with SN74CBT3305CD (SOIC tube), SN74CBT3305CDGKR (VSSOP), and SN74CBT3305CPWR (TSSOP). All variants use the same logic diagram, timing specs, and electrical characteristics; only package type, marking, and reel quantity differ. No PCB redesign is needed when migrating between SOIC, TSSOP, or VSSOP versions of SN74CBT3305CDR and its siblings.