Texas Instruments SN74CBT3345CDGVR

Overview

SN74CBT3345CDGVR from Texas Instruments is an 8-bit bidirectional FET bus switch IC with dual OE control, 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), and undershoot protection to −2 V on A/B ports. It enables low-distortion signal gating in USB interfaces and memory interleaving applications operating across 0–5-V signaling levels.

For engineers reviewing the SN74CBT3345CDGVR datasheet, SN74CBT3345CDGVR pinout, SN74CBT3345CDGVR application, or SN74CBT3345CDGVR equivalent, key selection criteria include Ioff partial-power-down support, 5.5-pF OFF-state I/O capacitance, dual active-high/active-low enable logic, and TVSOP (DGV) package compatibility with high-density PCB layouts.

Technical Context

This device implements TTL-compatible FET switching with independent high-impedance control via complementary OE inputs: OE high *or* OE low enables bidirectional conduction between A and B ports; both OE low and OE high disables the switch. The internal undershoot-protection circuitry actively clamps transient excursions below −2 V while maintaining OFF-state isolation.

It supports mixed-voltage domain interfacing (0.8 V to 5 V) without level translation, features 3 µA max ICC quiescent current, and meets JESD 78 Class II latch-up immunity (>100 mA). Thermal resistance for the DGV package is 92°C/W, confirming suitability for thermally constrained industrial and embedded designs.

Key Specifications

Pinout & Package

SN74CBT3345CDGVR uses a 20-pin TVSOP (DGV) package measuring 4.4 mm × 3.6 mm × 1.05 mm, optimized for fine-pitch surface-mount assembly and thermal performance (θJA = 92°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3345CDGVR, SN74CBTD3305PWR trades undershoot resilience and voltage flexibility for higher bit count, while PI3CHD3245LEX extends low-VCC capability at the cost of added design complexity for transient protection-making SN74CBT3345CDGVR optimal for robust 4–5.5 V mixed-signal isolation.

Availability

SN74CBT3345CDGVR is available at Aetrix Electronics and suitable for USB interface design, memory interleaving architectures, and bus isolation circuits requiring stable component supply, RoHS-compliant packaging, and long-term industrial lifecycle support.

Supply support for SN74CBT3345CDGVR 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 SN74CBT3345CDGVR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital systems where timing integrity and power-domain isolation are critical.

FAQ

What is the maximum undershoot voltage the SN74CBT3345CDGVR can withstand on its A and B ports?

The SN74CBT3345CDGVR provides active undershoot protection up to −2 V on both A and B ports, as verified by transient testing per Figures 1 and 2 in the SCDS129A datasheet. This protection is implemented via internal sensing circuitry that forces the switch into a guaranteed OFF state during negative excursions, preventing false conduction or latch-up. The SN74CBT3345CDGVR maintains this rating across its full operating temperature range of −40°C to 85°C.

Does the SN74CBT3345CDGVR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3345CDGVR supports partial-power-down operation via its Ioff feature, which limits leakage current to 10 µA when VCC = 0 V. This is achieved through internal circuitry that disables the FET channels and isolates the A/B ports from backflow current, ensuring safe operation during power sequencing or hot-swap events. The SN74CBT3345CDGVR meets JESD 78 Class II latch-up immunity (>100 mA), further enhancing system reliability during transitional states.

What are the recommended pull-up/pull-down resistors for OE and OE pins during power-up to ensure high-impedance state?

To guarantee high-impedance state during power-up or power-down, OE should be tied to VCC through a pull-up resistor and OE to GND through a pull-down resistor. The minimum resistor value depends on the driver's current-sinking/sourcing capability; TI recommends values ≥10 kΩ for standard CMOS drivers. This ensures OE remains high and OE low until valid control logic is applied, preventing unintended bus contention. The SN74CBT3345CDGVR datasheet specifies this requirement in Section "description/ordering information (continued)".

Can the SN74CBT3345CDGVR interface between 1.8-V and 5-V logic domains without external level shifters?

Yes, the SN74CBT3345CDGVR supports direct interfacing between 1.8-V and 5-V logic domains because its data I/Os accept 0–5.5-V signaling levels independent of VCC, and its control inputs are compatible with TTL and 5-V/3.3-V CMOS outputs. The device does not translate voltage levels but passes signals bi-directionally with minimal distortion-enabling clean signal coupling across voltage islands. This behavior is confirmed in the "Data I/Os Support 0 to 5-V Signaling Levels" specification and functional table of the SN74CBT3345CDGVR datasheet.

What is the thermal resistance (θJA) of the SN74CBT3345CDGVR in its TVSOP (DGV) package, and how does it affect PCB layout?

The SN74CBT3345CDGVR in the TVSOP (DGV) package has a junction-to-ambient thermal resistance (θJA) of 92°C/W, as specified in the Absolute Maximum Ratings table. This value assumes standard JEDEC 2-layer board conditions; actual performance improves with enhanced copper pour, thermal vias, and airflow. For reliable operation at full rated current, PCB layout must include adequate thermal relief-TI recommends minimum 10 mm² copper pad connected to internal ground planes via ≥4 thermal vias (0.3-mm diameter) beneath the exposed pad area. This thermal design guidance applies specifically to the SN74CBT3345CDGVR DGV variant.