Texas Instruments SN74CB3T3125RGYR

Overview

SN74CB3T3125RGYR from Texas Instruments is a quadruple FET bus switch IC supporting mixed-mode voltage translation across 2.5-V, 3.3-V, and 5-V signaling domains. It features bidirectional data flow, 5 Ω typical ON-state resistance, 4.5 pF typical OFF-state I/O capacitance, and operates from 2.3 V to 3.6 V supply. It enables level-shifting in USB interfaces and bus isolation circuits where 5-V inputs must drive 3.3-V or 2.5-V logic.

For engineers reviewing the SN74CB3T3125RGYR datasheet, SN74CB3T3125RGYR pinout, SN74CB3T3125RGYR application, or SN74CB3T3125RGYR equivalent, key selection considerations include its 5-V-tolerant I/Os with device powered up or down, Ioff partial-power-down support, near-zero propagation delay (0.15 ns typical), and VQFN-14 (RGY) package compatibility with high-density PCB layouts.

Technical Context

The SN74CB3T3125RGYR implements four independent 1-bit FET bus switches, each controlled by an active-low enable (1OE–4OE). Its MOSFET-based architecture provides rail-to-rail signal pass-through with output voltage tracking VCC, enabling seamless 5-V-to-3.3-V and 5-V/3.3-V-to-2.5-V down-translation. The device supports undervoltage clamping on all I/Os and control inputs via integrated diodes.

It is fully characterized for partial-power-down operation: when VCC = 0 V, Ioff limits backflow current to ≤10 μA while maintaining high-impedance isolation between A and B ports. Thermal performance is specified with RθJA = 55.5°C/W (VQFN), and ESD robustness includes ±2000-V HBM and ±1000-V CDM per JESD22.

Key Specifications

Pinout & Package

VQFN-14 (RGY) package, 3.50 mm × 3.50 mm body, 0.5-mm pitch, wettable flank terminals, RoHS-compliant NiPdAu finish, MSL Level-2 (260°C, 1 year).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTLV3125RGYR, the SN74CB3T3125RGYR trades slightly higher ron for guaranteed 5-V I/O tolerance and broader mixed-voltage interoperability; compared with TS3A24159RGTR, it delivers deterministic digital-level translation and system-level power-down safety - making it uniquely suited for mixed-rail digital interconnects.

Availability

SN74CB3T3125RGYR is available at Aetrix Electronics and suitable for USB interface isolation, processor bus expansion, hot-swappable module interfaces, and legacy peripheral integration requiring stable component supply and long-term manufacturability.

Supply support for SN74CB3T3125RGYR 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 decades of experience in high-reliability interface ICs.

The SN74CB3T3125RGYR belongs to TI's CB3T bus switch family, designed specifically for low-latency, mixed-voltage digital interconnect in space-constrained portable and industrial systems.

FAQ

What is the maximum allowable input voltage on the I/O pins of the SN74CB3T3125RGYR?

The SN74CB3T3125RGYR supports a VI/O range of 0 V to 5.5 V, with full 5-V tolerance whether the device is powered (VCC = 2.3–3.6 V) or unpowered (VCC = 0 V). This is enabled by internal FET architecture and clamp diodes, allowing direct connection to 5-V buses without external protection. Absolute maximum rating is 7 V, but operation above 5.5 V is not recommended for reliability.

Does the SN74CB3T3125RGYR support bidirectional signal flow without direction control pins?

Yes, the SN74CB3T3125RGYR supports true bidirectional signal flow on each A/B port pair without requiring direction control. When enabled (OE low), the FET switch conducts equally in both directions, and output voltage levels track VCC regardless of signal origin. This eliminates timing skew and simplifies routing in synchronous bus architectures like address/data multiplexing.

How does the Ioff feature of the SN74CB3T3125RGYR protect downstream circuitry during partial power-down?

The Ioff feature limits reverse current to ≤10 μA when VCC = 0 V, preventing damaging backflow from powered I/O lines into the unpowered SN74CB3T3125RGYR. This ensures isolation between subsystems during firmware-controlled sleep modes or modular board removal, satisfying JESD78 latch-up immunity requirements and eliminating need for external blocking diodes in hot-swap designs.

What is the typical ON-state resistance (ron) of the SN74CB3T3125RGYR and how does it affect signal integrity?

The SN74CB3T3125RGYR has a typical ron of 5 Ω at VCC = 2.5 V and IO = 24 mA. This low resistance minimizes voltage drop (<120 mV at 24 mA) and insertion loss, preserving logic thresholds and rise/fall times in high-speed digital buses. Combined with 4.5-pF OFF-capacitance, it enables clean signal pass-through up to 100 MHz without waveform distortion or timing jitter.

Can the SN74CB3T3125RGYR be used to translate between 1.8-V and 3.3-V logic levels?

Yes, the SN74CB3T3125RGYR supports 1.8-V to 3.3-V translation when configured with VCC = 3.3 V: a 1.8-V input on the A port produces a ~3.3-V output on the B port, and vice versa. Its data I/Os explicitly support 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, and 5 V signaling levels, making it suitable for heterogeneous voltage domain bridging in modern SoC designs.