Texas Instruments SN74CBT3345CRGYR

Overview

SN74CBT3345CRGYR from Texas Instruments is an 8-bit bidirectional FET bus switch IC with dual enable control (OE/OE), 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), and undershoot protection up to −2 V on A/B ports. It operates from 4 V to 5.5 V and supports mixed-voltage signaling (0.8 V to 5 V) in USB interface and memory interleaving applications.

For engineers reviewing the SN74CBT3345CRGYR datasheet, SN74CBT3345CRGYR pinout, SN74CBT3345CRGYR application, or SN74CBT3345CRGYR equivalent, key selection criteria include Ioff partial-power-down support, 5.5 pF typical OFF-state I/O capacitance, bidirectional signal gating capability, and QFN-20 (RGY) package thermal performance (θJA = 37°C/W).

Technical Context

The SN74CBT3345CRGYR implements TTL-compatible FET switching with active undershoot-protection circuitry that senses −2 V transients on A/B ports and forces OFF-state isolation. Its dual OE inputs provide flexible enable logic: high on OE or low on OE activates bidirectional conduction between A and B ports.

It features Ioff protection for partial-power-down mode, ensuring no backflow current when VCC = 0 V, and integrates clamp diodes on all data and control inputs. The device maintains high-impedance isolation during power-up/down when OE is pulled to VCC and OE to GND via external resistors.

Key Specifications

Pinout & Package

SN74CBT3345CRGYR uses a 20-pin QFN package (RGY) with 4 mm × 4 mm body, 0.5 mm pitch, and exposed thermal pad. Pin 1 is marked by a dot; the package is RoHS-compliant and moisture-sensitive level 2 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3345CRGYR, SN74CBTD3305PW offers more channels but sacrifices undershoot resilience and ON-resistance performance, while SN74LVC1G3157DCKR provides compact SPDT control at lower voltage but cannot replace an 8-bit bidirectional bus switch in memory or USB isolation roles.

Availability

SN74CBT3345CRGYR is available at Aetrix Electronics and suitable for USB interface design, memory interleaving systems, and bus isolation circuits requiring stable component supply, RoHS compliance, and QFN thermal performance.

Supply support for SN74CBT3345CRGYR 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 IC design.

The SN74CBT3345CRGYR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for ultra-low-latency, bidirectional signal routing in mixed-voltage digital systems including computing, communications, and industrial control.

FAQ

What is the maximum undershoot voltage the SN74CBT3345CRGYR can withstand on its A and B ports?

The SN74CBT3345CRGYR provides active undershoot protection up to −2 V on both A and B ports, verified per datasheet SCDS129A. This protection is implemented via internal sensing circuitry that forces the switch into a guaranteed OFF state during transient events, preventing false conduction and safeguarding connected logic. The −2 V rating applies across the full operating temperature range (−40°C to 85°C) and is independent of VCC level within specification.

Does the SN74CBT3345CRGYR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3345CRGYR supports partial-power-down operation via its Ioff feature. When VCC = 0 V, the device limits back-current to ≤10 µA, preventing damaging reverse current flow from live I/O lines into the unpowered IC. This behavior is intrinsic to the FET architecture and requires no external components. During Ioff operation, the A and B ports remain in high-impedance isolation, making SN74CBT3345CRGYR suitable for hot-swap and multi-rail systems where subsystems power up/down asynchronously.

What is the typical ON-state resistance of the SN74CBT3345CRGYR, and how does it affect signal integrity?

The SN74CBT3345CRGYR has a typical ON-state resistance (ron) of 3 Ω at VCC = 4.5 V and IO = 30 mA. This low ron minimizes voltage drop across the switch-less than 90 mV at 30 mA-and reduces power dissipation (<3 mW per channel). In practice, this preserves signal amplitude and edge rate in high-speed digital paths, avoids timing skew between parallel lines, and maintains impedance matching in 50-Ω systems. Measured ron remains stable across 0–5 V I/O voltage range, supporting mixed-voltage signal translation without gain error.

Can the SN74CBT3345CRGYR be used for analog signal switching, and what parameters support that use case?

Yes, the SN74CBT3345CRGYR is qualified for analog signal switching. Its 3 Ω ron ensures low insertion loss, 5.5 pF Cio(OFF) minimizes crosstalk and loading, and flat ron vs. voltage curve (0–5 V) delivers consistent performance across signal swing. The device exhibits no DC offset or switching glitches, and its FET structure provides symmetrical conduction in both directions. These characteristics make SN74CBT3345CRGYR suitable for audio routing, sensor multiplexing, and other low-distortion analog applications where bandwidth and linearity are critical.

What are the recommended power-up sequencing guidelines for reliable operation of the SN74CBT3345CRGYR?

To ensure high-impedance state during power-up or power-down, OE must be tied to VCC through a pull-up resistor and OE to GND through a pull-down resistor. TI specifies minimum resistor values based on driver strength-typically 10 kΩ suffices for standard CMOS drivers. This prevents undefined switch states that could cause bus contention or excessive current draw. The SN74CBT3345CRGYR does not require strict VCC ramp rate control, but maintaining OE/OE bias before VCC reaches 1 V ensures deterministic behavior across all temperature and process corners.