Texas Instruments SN74CBT3245CRGYR

Overview

SN74CBT3245CRGYR from Texas Instruments is an 8-bit bidirectional FET bus switch IC with near-zero propagation delay (0.15 ns typical at 5 V), 3 Ω typical ON-state resistance, and undershoot protection up to −2 V on both A and B ports. It operates from 4 V to 5.5 V, supports 0–5-V signaling across multiple logic families (1.2 V to 5 V), and enables bus isolation in high-speed digital systems.

For engineers reviewing the SN74CBT3245CRGYR datasheet, SN74CBT3245CRGYR pinout, SN74CBT3245CRGYR application, or SN74CBT3245CRGYR equivalent, key selection criteria include its low r_on, I_off-enabled partial-power-down capability, ±128 mA switch current rating, and VQFN-20 (RGY) package thermal performance (θ_JA = 37°C/W).

Technical Context

The SN74CBT3245CRGYR implements TTL-compatible control inputs with undervoltage lockout and active undershoot-protection circuitry that forces OFF-state isolation when A/B port voltages dip below −2 V. Its FET-based architecture eliminates DC path between ports during disable, enabling true high-impedance isolation.

It features a single OE input controlling all eight bidirectional channels simultaneously, with enable/disable times of 1.5 ns (typical) and propagation delay dominated by the RC time constant of r_on and load capacitance. 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

VQFN-20 (RGY) package: 3.5 mm × 4.5 mm, 0.5 mm pitch, exposed thermal pad (Pin 21), 1 mm max height. RoHS-compliant, moisture sensitivity level 2 (260°C peak reflow, 1-year floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3245CRGYR, SN74CBTD3384CDBQR offers more channels but sacrifices undershoot resilience, while PI3CH400QE extends voltage flexibility at the cost of verified I_off safety-making SN74CBT3245CRGYR the optimal choice for robust, mixed-voltage, power-sequenced designs.

Availability

SN74CBT3245CRGYR is available at Aetrix Electronics and suitable for USB interface isolation, memory interleaving, and industrial bus gating requiring stable component supply, long-term lifecycle support, and RoHS-compliant VQFN packaging.

Supply support for SN74CBT3245CRGYR 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 50 years of innovation in high-reliability interface solutions.

The SN74CBT3245CRGYR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for ultra-low-latency, low-distortion signal routing in high-speed digital systems where timing predictability and voltage-domain bridging are critical.

FAQ

What is the maximum undershoot voltage the SN74CBT3245CRGYR can withstand on its A and B ports?

The SN74CBT3245CRGYR provides active undershoot protection up to −2 V on both A and B ports. This is achieved through internal sensing circuitry that forces the switch into a guaranteed OFF state during negative transients, preventing unintended conduction and protecting downstream components. This specification is validated per test conditions in the datasheet (VCC = 5.5 V, switch OFF).

Does the SN74CBT3245CRGYR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3245CRGYR supports partial-power-down via its I_off feature, which limits leakage to 10 µA maximum when VCC = 0 V. This prevents damaging backflow current from live I/O lines into a powered-down device, enabling safe hot-swap and staged power sequencing. The isolation remains effective even when VCC is unpowered, as confirmed in the absolute maximum ratings table.

What is the thermal performance of the SN74CBT3245CRGYR in its RGY package?

The SN74CBT3245CRGYR in the VQFN-20 (RGY) package has a specified junction-to-ambient thermal resistance (θ_JA) of 37°C/W under standard JEDEC test conditions. This value assumes proper PCB layout with the exposed thermal pad soldered to a minimum 100 mm² copper pour, enabling reliable operation at full rated current across the −40°C to 85°C ambient range.

Can the SN74CBT3245CRGYR interface between 1.8-V and 5-V logic domains without external level shifters?

Yes, the SN74CBT3245CRGYR supports 0–5.5 V signaling on its A and B I/O ports independently of VCC (4–5.5 V), allowing direct connection between 1.8-V, 2.5-V, 3.3-V, and 5-V logic domains. Its voltage-tolerant architecture eliminates the need for discrete level translators while maintaining bidirectional signal integrity and low r_on.

What is the recommended power-up sequence for the SN74CBT3245CRGYR to ensure high-impedance state at startup?

To guarantee high-impedance state during power-up, OE must be held high (inactive) until VCC stabilizes. TI recommends tying OE to VCC through a pull-up resistor (value determined by driver sink capability); this ensures the switch remains OFF until firmware or system logic intentionally asserts OE low. Failure to do so may cause momentary bus contention.