Texas Instruments SN74CBT3257CRGYR

Overview

SN74CBT3257CRGYR from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer with bidirectional signal routing, 3 Ω typical ON-state resistance, <0.24 ns propagation delay at 4 V, and −2 V undershoot protection on A/B ports. It operates from 4 V to 5.5 V and supports 0–5 V signaling levels across USB interface and bus isolation applications.

For engineers reviewing the SN74CBT3257CRGYR datasheet, SN74CBT3257CRGYR pinout, SN74CBT3257CRGYR application, or SN74CBT3257CRGYR equivalent, this page delivers verified electrical specs, QFN-16 package layout, I²C bus expansion capability, partial-power-down (Ioff) support, and real-world analog/digital gating use cases - all confirmed from TI's SCDS137 datasheet and packaging addendum.

Technical Context

The SN74CBT3257CRGYR implements four independent single-pole double-throw (SPDT) FET switches controlled by one select (S) and one output-enable (OE) input. Each switch features active undershoot-protection circuitry that clamps A/B port voltages down to −2 V while maintaining OFF-state isolation.

It uses TTL-compatible control inputs (VIH = 2 V min, VIL = 0.8 V max), supports 0–5.5 V data I/Os regardless of VCC level, and guarantees high-impedance isolation during power-up/down when OE is pulled up to VCC. The device meets JESD 78 Class II latch-up (>100 mA) and JESD 22 ESD ratings (2000-V HBM, 1000-V CDM).

Key Specifications

Pinout & Package

VQFN-16 (RGY) package: 3.0 mm × 4.5 mm body, 0.4 mm pitch, exposed thermal pad, 1.0 mm max height, moisture sensitivity level (MSL) 2–260°C/1 year.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FET multiplexer applications.

Compared with SN74CBT3257CRGYR, SN74CBTD3384CDR offers greater channel count but sacrifices undershoot resilience and precision low-rON performance, while TS3A27518ERTER delivers lower resistance and better ESD rating at the cost of 5 V compatibility and Ioff safety - making SN74CBT3257CRGYR uniquely suited for robust, mixed-voltage industrial bus switching.

Availability

SN74CBT3257CRGYR is available at Aetrix Electronics and suitable for USB interface design, industrial bus isolation, I²C expansion, and low-distortion analog signal gating requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant VQFN packaging.

Supply support for SN74CBT3257CRGYR 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 components.

The SN74CBT3257CRGYR belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in mixed-signal systems where timing fidelity, voltage flexibility, and transient resilience are critical.

FAQ

What is the maximum undershoot voltage the SN74CBT3257CRGYR can withstand on its A/B ports?

The SN74CBT3257CRGYR provides active undershoot protection rated to −2 V on all A and B port pins. This is verified per TI's SCDS137 datasheet Section 6, where VOUTU is specified at 2 V minimum under VCC = 5.5 V, switch-OFF conditions. The protection circuit senses sub-ground excursions and forces the FET into a guaranteed OFF state, preventing false conduction or latch-up.

Does the SN74CBT3257CRGYR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3257CRGYR supports partial-power-down via its Ioff feature. When VCC = 0 V, Ioff is guaranteed ≤10 µA across the full 0–5.5 V I/O voltage range, blocking damaging back-current flow through powered-down switches. This behavior is validated in the Electrical Characteristics table (page 5) and enables safe integration into multi-rail systems with independent power sequencing.

What is the typical ON-state resistance (ron) of the SN74CBT3257CRGYR, and how does it affect signal integrity?

The SN74CBT3257CRGYR has a typical ON-state resistance of 3 Ω at VCC = 4.5 V, IO = 30 mA. This low ron minimizes insertion loss and voltage droop in high-speed digital or analog signal paths - critical for preserving eye diagram margins in USB 2.0 or reducing THD+N in audio gating applications. The datasheet confirms ron remains ≤6 Ω across all operating conditions.

Can the SN74CBT3257CRGYR interface directly with 1.8 V and 5 V logic families simultaneously?

Yes, the SN74CBT3257CRGYR supports 0–5.5 V signaling on all data I/O pins regardless of VCC level (4–5.5 V), enabling seamless interfacing between 1.8 V, 2.5 V, 3.3 V, and 5 V logic families. Control inputs accept TTL/CMOS thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V), and no external level shifters are required - confirmed in the Recommended Operating Conditions table (page 4) and Applications section (page 1).

What package type and thermal characteristics apply to the SN74CBT3257CRGYR?

The SN74CBT3257CRGYR uses a 16-pin VQFN package (RGY), measuring 3.0 mm × 4.5 mm with 0.4 mm pitch and an exposed thermal pad. Its thermal impedance θJA is 39°C/W (per JESD 51-5), significantly lower than SOIC (73°C/W) or TSSOP (108°C/W) variants - enabling higher sustained current handling and improved reliability in compact, thermally constrained PCB layouts.