Texas Instruments SN74CBTD3305CPWR

Overview

SN74CBTD3305CPWR 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 voltage domain bridging and signal integrity are critical.

For engineers reviewing the SN74CBTD3305CPWR datasheet, SN74CBTD3305CPWR pinout, SN74CBTD3305CPWR application, or SN74CBTD3305CPWR equivalent, key selection criteria include its dual-channel independent enable control, −2-V undershoot tolerance on A/B ports, Ioff partial-power-down support, and TSSOP-8 package compatibility with high-density PCB layouts.

Technical Context

The SN74CBTD3305CPWR implements two independent TTL-compatible FET switches, each controlled by dedicated OE inputs (1OE, 2OE), enabling per-channel ON/OFF state management. Its internal diode-connected VCC path provides passive 5-V-to-3.3-V level shifting without external components, while active undershoot-protection circuitry clamps A/B port voltages down to −2 V during off-isolation.

It supports mixed-voltage signaling (0.8 V to 5 V) on data I/Os and accepts TTL/3.3-V/5-V CMOS logic on controls. The device guarantees latch-up immunity >100 mA (JESD 78 Class II) and meets 2000-V HBM / 1000-V CDM ESD standards, making it suitable for hot-plug and mixed-rail industrial interfaces.

Key Specifications

Pinout & Package

TSSOP-8 package (PW), 3.0 mm × 4.4 mm body, 0.65 mm pitch, 1.2 mm max height, moisture sensitivity level 1 (260 °C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3305CPWR, SN74CBT3244PWR offers higher density but lacks level shifting and undershoot hardening, while TS3A24157RGTR delivers superior analog performance at lower voltage but cannot interface 5-V buses or withstand −2-V faults-making SN74CBTD3305CPWR uniquely suited for robust 5-V/3.3-V boundary control.

Availability

SN74CBTD3305CPWR is available at Aetrix Electronics and suitable for USB interface isolation, memory interleaving, and industrial bus isolation requiring stable component supply, long-term lifecycle support, and RoHS-compliant TSSOP packaging.

Supply support for SN74CBTD3305CPWR 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 industrial, automotive, and communications markets.

The SN74CBTD3305CPWR belongs to TI's 74CBT family of high-speed bus switches, engineered specifically for voltage-domain bridging, hot-swap resilience, and low-distortion signal routing in mixed-supply digital systems.

FAQ

What is the maximum undershoot voltage the SN74CBTD3305CPWR can tolerate on its A and B ports?

The SN74CBTD3305CPWR provides active undershoot protection up to −2 V on both A and B ports when the switch is in the OFF state. This is verified per the absolute maximum ratings and undershoot characteristics table in the official datasheet (SCDS126A), where VIKU is specified at −2 V typical under OFF conditions. This capability prevents false turn-on and ensures reliable isolation during cable hot-plug events or ESD transients.

Does the SN74CBTD3305CPWR support true bidirectional level shifting between 5-V and 3.3-V logic domains?

Yes, the SN74CBTD3305CPWR supports bidirectional 5-V-to-3.3-V level shifting via an integrated diode in series with VCC. When a 5-V signal is applied to the A port, the internal diode drops ~1.7 V, delivering ~3.3 V to the B port; the reverse path operates similarly due to FET symmetry. This is explicitly confirmed in the device description and Figure 6 of the SCDS126A datasheet, and does not require external components or direction control.

Can the SN74CBTD3305CPWR be used in partial-power-down systems where VCC is disconnected while other rails remain active?

Yes, the SN74CBTD3305CPWR includes Ioff support, limiting OFF-state current to 10 μA maximum when VCC = 0 V and I/O voltages range from 0 V to 5.5 V. This feature prevents damaging back-current flow from live I/O lines into the unpowered device, satisfying JEDEC JESD78 Class II latch-up requirements and enabling safe integration into systems with staggered power sequencing-such as battery-backed real-time clocks interfacing with main 5-V buses.

What is the typical ON-state resistance (ron) of the SN74CBTD3305CPWR and how does it affect signal integrity?

The SN74CBTD3305CPWR has a typical ON-state resistance of 3 Ω at VCC = 4.5 V, as measured per the electrical characteristics table in SCDS126A. This low ron minimizes voltage drop across the switch (e.g., <100 mV at 30 mA), reduces power dissipation, and preserves signal rise/fall times-enabling clean transmission of fast digital edges and low-distortion analog waveforms without external buffering.

Is the SN74CBTD3305CPWR pin-compatible with other devices in the 74CBT family, such as the SN74CBTD3306?

No, the SN74CBTD3305CPWR is not pin-compatible with the SN74CBTD3306. While both are dual bus switches in TSSOP-8 packages, the SN74CBTD3306 uses inverted OE logic (active-low) and different pin assignments: its 1OE is on pin 1, whereas SN74CBTD3305CPWR places 1OE on pin 1 but assigns 1A/1B/2B/2A differently (1A=2, 1B=3, 2B=7, 2A=8). Layout reuse is not possible without redesign-confirmed by comparing logic diagrams and pinouts in SCDS126A and SCDS127A datasheets.