Texas Instruments SN74CB3T3125PWR

Overview

SN74CB3T3125PWR from Texas Instruments is a quadruple 1-bit FET bus switch optimized for mixed-mode voltage-level translation between 0–5 V signaling domains, featuring 5 Ω typical ON-state resistance, 4.5 pF typical OFF-state I/O capacitance, and bidirectional signal flow with near-zero propagation delay (0.15 ns min). It enables 5-V-to-3.3-V or 5-V/3.3-V-to-2.5-V translation in USB interfaces and bus isolation circuits.

For engineers reviewing the SN74CB3T3125PWR datasheet, SN74CB3T3125PWR pinout, SN74CB3T3125PWR application, or SN74CB3T3125PWR equivalent, key selection considerations include its 2.3–3.6 V VCC range, 5-V-tolerant I/Os under powered-up and powered-down conditions, Ioff partial-power-down support, and TSSOP-14 package compatibility with legacy board layouts.

Technical Context

The SN74CB3T3125PWR implements four independent FET-based analog switches, each controlled by an active-low enable (1OE–4OE), enabling per-channel ON/OFF control. Its MOSFET architecture provides rail-to-rail bidirectional conduction without directionality constraints, and output voltage tracks VCC during level translation.

It supports true mixed-mode operation: data I/Os accept 0–5 V inputs (including 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, 5 V logic levels) while VCC remains at 2.3–3.6 V, and maintains 5-V tolerance regardless of power state-critical for hot-swap and partial-power-down systems.

Key Specifications

Pinout & Package

TSSOP-14 (PW) package: 5.00 mm × 4.40 mm body, 0.65 mm lead pitch, surface-mount, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3T3125PWR, SN74CBT3125PWR lacks Ioff and 5-V tolerance-limiting use in partial-power-down systems-while TS3A24159PWR trades 5-V robustness for lower ron and finer low-voltage support, making SN74CB3T3125PWR uniquely balanced for industrial mixed-rail isolation.

Availability

SN74CB3T3125PWR is available at Aetrix Electronics and suitable for USB interface isolation, multi-rail bus translation, and hot-swappable module backplanes requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant TSSOP packaging.

Supply support for SN74CB3T3125PWR 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 precision analog design and industrial-grade reliability.

The SN74CB3T3125PWR belongs to TI's CB3T family of low-voltage FET bus switches, engineered specifically for mixed-signal voltage translation and hot-plug-safe isolation in industrial, computing, and communications infrastructure.

FAQ

What is the maximum input voltage the SN74CB3T3125PWR can tolerate on its I/O pins?

The SN74CB3T3125PWR supports 0–5.5 V on all data I/O pins (1A–4A, 1B–4B) regardless of VCC state-whether powered up or fully powered down. This 5-V tolerance is explicitly specified in Absolute Maximum Ratings and verified per JEDEC standards, enabling direct interfacing with 5-V TTL, LVTTL, and legacy peripherals without external clamping.

Does the SN74CB3T3125PWR require pull-up resistors on its OE pins?

Yes-the SN74CB3T3125PWR OE pins (1OE–4OE) are active-low, and to ensure high-impedance state during power-up or power-down, TI recommends tying each OE to VCC via a pull-up resistor. The minimum value depends on the driving source's current-sinking capability, typically 10 kΩ for standard CMOS drivers, as confirmed in Section 8.1 of the datasheet.

Can the SN74CB3T3125PWR translate 1.8-V signals to 3.3-V levels?

No-the SN74CB3T3125PWR does not perform upward level translation. Its output voltage tracks VCC, so with VCC = 3.3 V, it translates 5-V or 3.3-V inputs down to ~3.3 V, but cannot boost 1.8-V inputs to 3.3-V. For up-translation, a dedicated level shifter like TXS0108E is required; SN74CB3T3125PWR is strictly a down-translating, VCC-referenced switch.

What is the thermal performance of the SN74CB3T3125PWR in TSSOP-14 package?

In the TSSOP-14 (PW) package, the SN74CB3T3125PWR has a junction-to-ambient thermal resistance (RθJA) of 123.3 °C/W. At maximum recommended load (128 mA per channel) and 85 °C ambient, junction temperature remains within safe limits (<125 °C), validated per JEDEC JESD51-2. No heatsink is required for typical operation.

How does the SN74CB3T3125PWR handle undershoot on its I/O lines?

The SN74CB3T3125PWR integrates undershoot clamp diodes on all data and control inputs. When VI/O falls below GND, current is clamped at –1.2 V (VIK = –1.2 V at II = –18 mA), limiting negative transients and protecting downstream circuitry-eliminating the need for external Schottky clamps in most noise-prone industrial applications.