Texas Instruments SN74CBT3125CPWRE4

Overview

SN74CBT3125CPWRE4 from Texas Instruments is a quad 1-bit FET bus switch IC used for bidirectional signal gating in mixed-voltage digital systems. It features 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), undershoot protection to −2 V on A/B ports, and supports 0–5-V signaling across TTL/CMOS logic families - deployed in USB interface isolation and low-distortion data routing.

For engineers reviewing the SN74CBT3125CPWRE4 datasheet, SN74CBT3125CPWRE4 pinout, SN74CBT3125CPWRE4 application, or SN74CBT3125CPWRE4 equivalent, key selection criteria include Ioff partial-power-down capability, 5 pF typical OFF-state I/O capacitance, VCC operating range (4–5.5 V), and TSSOP-14 package compatibility with high-density PCB layouts.

Technical Context

The SN74CBT3125CPWRE4 implements four independent single-pole single-throw (SPST) FET switches, each controlled by a dedicated OE input (1OE–4OE). When OE is low, the A–B path conducts bidirectionally with minimal ron-induced distortion; when high, the switch enters high-impedance isolation with Ioff limiting backflow during partial power-down.

Its active undershoot-protection circuitry monitors A/B port voltage transients and forces switch disable if VI/O drops below −2 V, preventing false turn-on and latch-up. The device operates across −40°C to 85°C with full JESD 78 Class II latch-up immunity and 2000-V HBM ESD rating.

Key Specifications

Pinout & Package

TSSOP-14 (PW) package: 4.4 mm × 5.0 mm body, 0.65 mm pitch, 1.2 mm max height, lead-free NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3125CPWRE4, SN74CBTD3384CPWRE4 offers greater bit-width and bus arbitration logic at the cost of higher Ron and no −2 V undershoot guard; TS3A24159RGTR delivers lower Ron in narrow voltage range but omits Ioff and failsafe clamping - making SN74CBT3125CPWRE4 optimal for mixed-voltage industrial isolation where reliability under transient stress is critical.

Availability

SN74CBT3125CPWRE4 is available at Aetrix Electronics and suitable for USB interface isolation, industrial bus signal gating, and low-distortion analog routing requiring stable component supply, long-term lifecycle support, and RoHS-compliant TSSOP packaging.

Supply support for SN74CBT3125CPWRE4 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 IC design.

The SN74CBT3125CPWRE4 belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital systems - targeting USB, industrial I/O, and FPGA interconnect applications.

FAQ

What is the maximum undershoot voltage the SN74CBT3125CPWRE4 can withstand on its A/B ports?

The SN74CBT3125CPWRE4 provides active undershoot protection up to −2 V on both A and B ports. This is verified per test conditions in the datasheet (VCC = 5.5 V, switch OFF), where the internal protection circuit senses the event and forces the switch into the OFF state to prevent false conduction or latch-up. Exceeding −2 V risks violating absolute maximum ratings.

Does the SN74CBT3125CPWRE4 support bidirectional signal flow without external direction control?

Yes, the SN74CBT3125CPWRE4 supports fully bidirectional signal flow between each A and B terminal pair without any direction pin or control logic. Conduction occurs symmetrically when the corresponding OE input is low, and the FET architecture inherently permits current flow in either direction - confirmed by the "Bidirectional Data Flow" feature and functional table in the SCDS122A datasheet.

What is the thermal performance of the SN74CBT3125CPWRE4 in its TSSOP-14 (PW) package?

The SN74CBT3125CPWRE4 in the TSSOP-14 (PW) package has a specified thermal impedance θJA of 113°C/W. This value is measured per JESD 51-7 under standard JEDEC board conditions and reflects the device's ability to dissipate heat during continuous operation at rated current. Derating is recommended above 70°C ambient per the absolute maximum ratings table.

Can the SN74CBT3125CPWRE4 be used with 1.8-V or 2.5-V logic levels while powered from a 5-V supply?

Yes, the SN74CBT3125CPWRE4 supports 0–5-V signaling on its A/B I/O ports regardless of VCC (4–5.5 V), including 1.8-V and 2.5-V logic levels. Its data I/Os are voltage-translating - no level shifter needed - and control inputs accept TTL or 3.3-V/5-V CMOS logic, as explicitly stated in the "Data I/Os Support 0 to 5-V Signaling Levels" feature.

Is the SN74CBT3125CPWRE4 pin-compatible with other members of the SN74CBT3125C family?

Yes, the SN74CBT3125CPWRE4 shares identical pinout and functionality with all SN74CBT3125C variants in D, DB, DBQ, PW, and RGY packages - confirmed by the shared logic diagram, pin numbering, and function table across package drawings in the SCDS122A datasheet. All variants use the same 14-pin arrangement for OE/A/B/GND/VCC assignments.