Texas Instruments SN74CBTD3305CPW

Overview

SN74CBTD3305CPW from Texas Instruments is a dual 1-bit FET bus switch with integrated level shifting and −2-V undershoot protection, operating from 4.5 V to 5.5 V VCC. It enables bidirectional 5-V-to-3.3-V signal translation, features 3 Ω typical ON-state resistance, 5 pF typical OFF-state I/O capacitance, and near-zero propagation delay (0.15 ns). It is used in USB interface isolation and memory interleaving where robust signal integrity and voltage-level compatibility are required.

For engineers reviewing the SN74CBTD3305CPW datasheet, SN74CBTD3305CPW pinout, SN74CBTD3305CPW application, or SN74CBTD3305CPW equivalent, key selection criteria include its −2-V undershoot tolerance on A/B ports, Ioff partial-power-down support, 5-V/3.3-V bidirectional level shifting capability, and TSSOP-8 package compatibility with high-density PCB layouts.

Technical Context

The SN74CBTD3305CPW implements two independent FET-based transmission gates controlled by separate OE inputs (1OE, 2OE), each enabling bidirectional conduction between A and B ports when asserted high. Its internal diode-to-VCC architecture provides passive 5-V-to-3.3-V level downshifting without external components.

Active undershoot-protection circuitry monitors A/B port voltages and forces switch disablement during −2-V transients, preventing false turn-on and latch-up. The device supports Ioff isolation during partial power-down, ensuring no backflow current when VCC = 0 V and I/O pins remain at up to 5.5 V.

Key Specifications

Pinout & Package

TSSOP-8 package (PW), 3.0 mm × 4.4 mm body, 0.65 mm pitch, 1.2 mm max height, RoHS-compliant NIPDAU/SN lead 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 SN74CBTD3305CPW, SN74CBT3244PW offers more channels but sacrifices level shifting and undershoot protection, while SN74LVC1G3157DBVR provides smaller footprint and analog capability but lacks 5-V support, Ioff, and robust transient immunity-making SN74CBTD3305CPW uniquely suited for mixed-voltage, hot-plug, and high-speed digital isolation.

Availability

SN74CBTD3305CPW is available at Aetrix Electronics and suitable for USB interface isolation, memory interleaving, and mixed-voltage bus isolation requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant TSSOP packaging.

Supply support for SN74CBTD3305CPW 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 electronic components.

The SN74CBTD3305CPW belongs to TI's 74CBT family of high-speed CMOS bus switches, engineered specifically for low-distortion, level-translating digital signal routing in computing, communications, and industrial control systems.

FAQ

What is the maximum undershoot voltage the SN74CBTD3305CPW can withstand on its A and B ports?

The SN74CBTD3305CPW guarantees −2 V undershoot protection on both A and B ports when the switch is disabled. This is achieved through active undershoot-protection circuitry that senses negative transients and forces the FET into the OFF state, preventing false conduction. The specification is validated per test conditions in the datasheet (VCC = 5.5 V, switch OFF), and applies directly to the SN74CBTD3305CPW in its TSSOP-8 package.

Does the SN74CBTD3305CPW support level shifting from 3.3 V to 5 V, or only 5 V to 3.3 V?

The SN74CBTD3305CPW supports bidirectional data flow but provides level shifting only from 5 V (at the A or B port) down to approximately 3.3 V (at the opposite port) via its integrated diode-to-VCC architecture. When a 3.3-V signal is applied to one port, the other port reflects ~3.3 V (not boosted to 5 V). Thus, it performs 5-V-to-3.3-V downshifting-not upshifting-and maintains full bidirectional transparency for signals within the 0–5.5 V range.

Can the SN74CBTD3305CPW be used in partial-power-down mode, and what does Ioff guarantee?

Yes, the SN74CBTD3305CPW supports partial-power-down mode via its Ioff feature. When VCC = 0 V, the device limits current flow between live I/O pins (up to 5.5 V) and the unpowered supply rail to ≤10 μA (max), preventing damaging back-current and ensuring isolation. This behavior is guaranteed across temperature and is intrinsic to the SN74CBTD3305CPW's FET design-no external circuitry is required to achieve safe operation during power sequencing.

What is the typical ON-state resistance (ron) of the SN74CBTD3305CPW, and how does it affect signal integrity?

The SN74CBTD3305CPW has a typical ON-state resistance (ron) of 3 Ω at VCC = 4.5 V, measured between A and B terminals under 30 mA current. This low ron minimizes voltage drop and duty-cycle distortion, especially critical in high-speed digital applications such as memory address/control buses or USB differential pairs. At 100 mA, ron remains ≤6 Ω, ensuring predictable insertion loss and maintaining signal eye diagrams even under moderate drive loads.

Is the SN74CBTD3305CPW pin-compatible with other packages in the same family, such as the SOIC version?

Yes, the SN74CBTD3305CPW (TSSOP-8) shares identical pinout and electrical functionality with the SOIC-8 variant SN74CBTD3305CD, including identical pin numbering (1OE, 1A, 1B, GND, VCC, 2OE, 2B, 2A) and thermal/mechanical pad assignments. Both packages comply with JEDEC MO-153 (TSSOP) and MS-012 (SOIC) standards, enabling direct PCB footprint substitution where board space and thermal constraints permit-though thermal impedance differs (149°C/W vs. 97°C/W).