Texas Instruments SN74CB3T3125DGVR

Overview

SN74CB3T3125DGVR from Texas Instruments is a quadruple FET bus switch optimized for mixed-mode voltage-level translation between 0–5 V signaling domains, supporting bidirectional data flow with 5 Ω typical ON-state resistance, 4.5 pF OFF-state I/O capacitance, and operation across 2.3 V to 3.6 V VCC. 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 SN74CB3T3125DGVR datasheet, SN74CB3T3125DGVR pinout, SN74CB3T3125DGVR application, or SN74CB3T3125DGVR equivalent, key selection criteria 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 TVSOP-14 package compatibility with space-constrained portable designs.

Technical Context

The SN74CB3T3125DGVR implements four independent 1-bit FET bus switches, each controlled by an active-low enable (1OE–4OE). Its voltage-tracking output architecture ensures VOH ≈ VCC when VIH ≥ VCC + 1 V and ≤ 5.5 V, enabling seamless level shifting without external biasing.

Each switch supports bidirectional conduction with sub-1-ns enable/disable timing (ten/tdis ≤ 9 ns), operates over –40°C to 85°C, and features undershoot clamp diodes on all I/O and control pins. The Ioff specification guarantees <10 μA backflow current during power-down, ensuring system-level isolation in partial-power-down modes.

Key Specifications

Pinout & Package

SN74CB3T3125DGVR is housed in a 14-pin TVSOP (DGV) package measuring 3.60 mm × 4.40 mm, with 0.65 mm lead pitch and exposed thermal pad (not electrically connected). This ultra-thin, leaded package supports automated assembly and provides superior thermal performance versus TSSOP alternatives.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3T3125DGVR, SN74CBTLV3125PW offers lower resistance but no Ioff protection, while SN74AVC4T245RGYR adds direction control and dual-supply support at the cost of higher latency and layout complexity-making SN74CB3T3125DGVR optimal for simple, low-latency, power-aware bidirectional isolation.

Availability

SN74CB3T3125DGVR is available at Aetrix Electronics and suitable for USB interface design, industrial backplane isolation, and low-power portable equipment requiring stable component supply and long-term manufacturability.

Supply support for SN74CB3T3125DGVR 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 expertise in high-reliability interface solutions.

The SN74CB3T3125DGVR belongs to TI's CB3T family of low-voltage FET bus switches, engineered specifically for mixed-signal voltage translation and bus isolation in space- and power-constrained digital systems.

FAQ

What is the maximum input voltage the SN74CB3T3125DGVR can tolerate on its I/O pins?

The SN74CB3T3125DGVR supports a switch I/O voltage range of –0.5 V to 7 V per Absolute Maximum Ratings, with functional operation guaranteed for VI/O from 0 V to 5.5 V. Its 5-V-tolerant architecture allows inputs up to 5.5 V even when VCC is as low as 2.3 V, making it suitable for interfacing 5-V peripherals to lower-voltage logic without external clamping.

Does the SN74CB3T3125DGVR require external pull-up resistors on its enable pins?

Yes - to ensure a defined high-impedance state during power-up or power-down, each OE pin (1OE–4OE) of the SN74CB3T3125DGVR should be tied to VCC through a pull-up resistor. The minimum value depends on the driving source's current-sinking capability, but typical values range from 10 kΩ to 100 kΩ for standard CMOS drivers.

Can the SN74CB3T3125DGVR translate from 1.8 V to 3.3 V?

No - the SN74CB3T3125DGVR is designed for down-translation only (e.g., 5 V → 3.3 V or 3.3 V → 2.5 V) and does not support up-translation. Its output voltage tracks VCC, so setting VCC = 3.3 V allows 5-V or 3.3-V inputs to produce 3.3-V outputs, but a 1.8-V input will not be boosted to 3.3-V; for bidirectional or up-translation, a dual-supply translator like SN74AVC4T245 is required.

What is the thermal performance of the SN74CB3T3125DGVR in its TVSOP package?

In the TVSOP-14 (DGV) package, the SN74CB3T3125DGVR has a junction-to-ambient thermal resistance (RθJA) of 154.8°C/W. With its low 20 μA ICC and 5 Ω ron, self-heating is minimal under typical loads; derating is generally unnecessary below 64 mA per channel at 85°C ambient, provided standard PCB copper area (≥1 in²) is used for thermal relief.

How does the Ioff feature of the SN74CB3T3125DGVR protect system-level circuits?

The Ioff feature of the SN74CB3T3125DGVR limits reverse current to ≤10 μA when VCC = 0 V and I/O pins are biased to up to 5.5 V, preventing damaging backflow into a powered-down supply rail. This protects upstream drivers during hot-swap events, partial system resets, or sleep-mode transitions - a critical capability absent in non-Ioff bus switches like the SN74CBT3125 series.