Texas Instruments SN74CBT3125CDGVR

Overview

SN74CBT3125CDGVR from Texas Instruments is a quad 1-bit FET bus switch IC with TTL-compatible control inputs, 3 Ω typical ON-state resistance, <0.24 ns propagation delay at 4 V, and −2 V undershoot protection on A/B ports. It enables bidirectional signal gating in USB interfaces and bus isolation circuits operating across 0–5 V signaling levels.

For engineers reviewing the SN74CBT3125CDGVR datasheet, SN74CBT3125CDGVR pinout, SN74CBT3125CDGVR application, or SN74CBT3125CDGVR equivalent, key selection criteria include Ioff partial-power-down support, 5 pF OFF-state I/O capacitance, 3 µA max ICC, VCC range of 4–5.5 V, and TVSOP (DGV) package compatibility with high-density PCB layouts.

Technical Context

This device implements four independent single-pole single-throw (SPST) analog/digital bus switches using NMOS FETs with integrated undershoot-protection circuitry on both A and B terminals. Each switch is controlled by a dedicated OE input that drives the internal enable signal to connect or isolate the A–B path.

It supports mixed-voltage domain interfacing (0.8 V to 5 V) without level translation, maintains high-impedance isolation during power-up/down via Ioff, and features clamp diodes on all data and control pins to limit negative transients to −2 V under OFF-state conditions.

Key Specifications

Pinout & Package

SN74CBT3125CDGVR uses the TVSOP (DGV) package: 14-pin, 4.4 mm × 3.6 mm body, 0.65 mm pitch, 1.2 mm max height, with exposed thermal pad recommended for soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3125CDGVR, SN74CBTD3384CDW offers more channels but sacrifices undershoot hardening and adds 100% ron penalty, while TS3A24159RGTR delivers lower resistance at the cost of 5 V incompatibility and no Ioff-making SN74CBT3125CDGVR uniquely balanced for robust 5 V bus isolation.

Availability

SN74CBT3125CDGVR is available at Aetrix Electronics and suitable for USB interface design, industrial bus isolation, and low-distortion signal gating requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74CBT3125CDGVR 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 SN74CBT3125C family was designed for high-speed, low-distortion signal routing in mixed-voltage digital systems-targeting USB, industrial control, and test equipment where signal fidelity and robustness against transients are critical.

FAQ

What is the maximum signal voltage supported by SN74CBT3125CDGVR?

SN74CBT3125CDGVR supports data I/O voltages from 0 V to 5.5 V, including 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, and 5 V logic levels. Its absolute maximum VI/O rating is −0.5 V to 7 V, but operational integrity is guaranteed only within 0–5.5 V under recommended conditions. The device passes signals bidirectionally without level shifting.

Does SN74CBT3125CDGVR require external pull-up resistors on OE pins?

Yes-TI recommends tying each OE pin to VCC through a pull-up resistor to ensure high-impedance state during power-up or power-down. The minimum resistor value depends on the driver's current-sinking capability; typical values range from 4.7 kΩ to 10 kΩ for standard CMOS drivers. Leaving OE floating may cause undefined switch states.

Can SN74CBT3125CDGVR be used for analog signal switching?

Yes-SN74CBT3125CDGVR is specified for both digital and analog applications. Its 3 Ω ron, 5 pF Cio(OFF), and flat frequency response make it suitable for line-level audio, sensor signal routing, and other low-distortion analog paths up to ~100 MHz, provided signals remain within the 0–5.5 V VI/O range and do not exceed ±128 mA peak current.

What is the thermal performance of SN74CBT3125CDGVR in its TVSOP package?

SN74CBT3125CDGVR in the TVSOP (DGV) package has a thermal impedance θJA of 127°C/W, measured per JESD 51-7. This value assumes standard JEDEC 2-layer board conditions. For sustained operation near maximum ratings, thermal relief via PCB copper pour under the exposed pad is strongly advised to reduce junction temperature rise.

How does the undershoot protection circuit operate in SN74CBT3125CDGVR?

The undershoot protection circuit in SN74CBT3125CDGVR actively monitors A and B port voltages. When a transient pulls either port below −2 V relative to GND while the switch is OFF, internal clamping activates to hold the switch in the OFF state-preventing unintended conduction and potential latch-up. This occurs independently per channel and requires no external components.