Texas Instruments SN74CBT3126DGVR

Overview

SN74CBT3126DGVR from Texas Instruments is a quadruple FET bus switch IC used for bidirectional signal routing in high-speed digital systems. It features four independent 5-Ω on-state resistance switches, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and operates from 4 V to 5.5 V supply. It enables low-latency signal pass-through (tpd = 0.25 ns at VCC = 5 V) in memory address/data buses and logic-level translation applications.

For engineers reviewing the SN74CBT3126DGVR datasheet, SN74CBT3126DGVR pinout, SN74CBT3126DGVR application, or SN74CBT3126DGVR equivalent, key selection criteria include on-resistance matching across channels, propagation delay consistency, latch-up immunity (>250 mA per JESD 17), thermal performance in TVSOP packaging, and compatibility with 3.3-V/5-V mixed-signal bus architectures.

Technical Context

This device implements four independent NMOS transmission-gate bus switches, each controlled by a dedicated OE input. Each switch connects A and B ports bidirectionally when OE is high, presenting high-impedance isolation when OE is low. The architecture avoids internal latching and requires no external biasing beyond standard pull-down resistors on OE pins for power-up safety.

Designed for hot-swap and partial-power-down scenarios, the SN74CBT3126DGVR maintains I/O integrity under VCC ramp conditions via robust input clamp diodes (VIK = −1.2 V) and supports up to ±1 μA input leakage. Its 5-pF typical control-input capacitance and 4-pF off-state I/O capacitance minimize signal distortion in high-frequency data paths up to 100 MHz.

Key Specifications

Pinout & Package

SN74CBT3126DGVR 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 to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3126DGVR, SN74CBTD3384DBR offers double channel count but sacrifices 5-V compatibility and increases Ron, while 74LVC1G3157DCKR trades integration for broader voltage range and smaller footprint per switch-neither provides identical quad-channel, 5-V, low-Ron performance in TVSOP.

Availability

SN74CBT3126DGVR is available at Aetrix Electronics and suitable for memory subsystems, FPGA peripheral interfacing, hot-plug backplanes, and JTAG test infrastructure requiring stable component supply and long-term industrial lifecycle support.

Supply support for SN74CBT3126DGVR 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 logic and interface solutions.

The SN74CBT3126DGVR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for low-latency, low-distortion signal routing in high-speed digital interconnects-including memory, processor, and test-access architectures.

FAQ

What is the maximum continuous current rating per channel for the SN74CBT3126DGVR?

The SN74CBT3126DGVR supports a continuous channel current of 128 mA per switch, as specified in its absolute maximum ratings. This rating applies under steady-state DC conditions with proper PCB thermal design-particularly important in the TVSOP (DGV) package, which has a θJA of 127°C/W. Derating is recommended above +70°C ambient.

Does the SN74CBT3126DGVR require external pull-up or pull-down resistors on its OE pins?

Yes-the SN74CBT3126DGVR requires a pulldown resistor on each OE input to ensure high-impedance state during power-up or power-down. TI specifies tying OE to GND through a resistor whose minimum value depends on the driver's current-sourcing capability; typical values range from 1 kΩ to 10 kΩ for robust default isolation.

Can the SN74CBT3126DGVR be used for bidirectional level translation between 3.3-V and 5-V logic domains?

No-the SN74CBT3126DGVR does not perform active level translation. While it operates from 4 V to 5.5 V and accepts TTL-compatible inputs, its A/B ports conduct passively: output voltage swing is limited by the lower of the two connected rail voltages. For true 3.3-V ↔ 5-V translation, a dedicated level shifter like TXB0104 is required.

What is the thermal pad requirement for the SN74CBT3126DGVR in TVSOP packaging?

The SN74CBT3126DGVR in TVSOP (DGV) package includes an exposed thermal pad that must be soldered to a PCB copper pour connected to GND. TI recommends ≥80% solder coverage of the pad area (3.3 mm × 3.3 mm) to achieve optimal thermal dissipation and mechanical reliability-failure to do so may impair θJA performance and long-term solder joint integrity.

Is the SN74CBT3126DGVR pin-compatible with other packages in the same family, such as SN74CBT3126PWR?

Yes-SN74CBT3126DGVR shares identical pinout and function with SN74CBT3126PWR (TSSOP), SN74CBT3126DR (SOIC), and SN74CBT3126DBR (SSOP). All variants use the standard '126-type pin assignment: pins 1–7 and 8–14 follow the same OE/A/B/GND/VCC/... mapping, enabling direct PCB footprint interchangeability within the same package footprint class.