Texas Instruments SN74CBTD3861DW

Overview

SN74CBTD3861DW from Texas Instruments is a 10-bit FET bus switch with integrated level-shifting capability, designed for bidirectional 5-V-to-3.3-V signal translation between logic domains. It features 5-Ω on-state resistance, TTL-compatible inputs, and a single OE control enabling/disabling all ten channels simultaneously. It is used in mixed-voltage system interconnects such as memory expansion interfaces and processor peripheral buses.

For engineers reviewing the SN74CBTD3861DW datasheet, SN74CBTD3861DW pinout, SN74CBTD3861DW application, or SN74CBTD3861DW equivalent, key selection criteria include its 5-Ω r_on, 0.35-ns propagation delay, 4.5–5.5-V V_CC operation, OE-controlled high-impedance isolation, and SOIC-24 package compatibility with legacy board layouts.

Technical Context

The SN74CBTD3861DW implements a passive FET-based switching architecture with no internal logic gates-signal paths are direct analog connections between A and B ports. Its integrated diode-to-V_CC enables level shifting from 5-V inputs to 3.3-V outputs without external components.

Operation is controlled solely by the OE input: low enables conduction (A↔B), high places both ports in high-Z. The device does not buffer, invert, or regenerate signals-it preserves edge rate and voltage swing while adding minimal RC delay via its 5-Ω r_on and sub-5-pF off-capacitance.

Key Specifications

Pinout & Package

SN74CBTD3861DW is housed in a 24-pin SOIC (DW) package with 1.27-mm pitch, 7.5-mm body width, and 15.4-mm length. Pin 1 is located at the top-left corner adjacent to the index notch or dot marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3861DW, SN74CBT3245DW offers identical performance in an 8-bit form factor but cannot replace the 10-bit channel count without layout changes; SN74LVC245APW introduces direction logic and lacks native 5-V-to-3.3-V translation, increasing BOM count and timing uncertainty in mixed-voltage designs.

Availability

SN74CBTD3861DW is available at Aetrix Electronics and suitable for memory expansion interfaces, processor peripheral buses, legacy system voltage bridging, and industrial control backplanes requiring stable component supply and long-term obsolescence management.

Supply support for SN74CBTD3861DW 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 logic and interface solutions.

The SN74CBTD3861DW belongs to TI's CBTD-series of FET bus switches, engineered specifically for low-latency, bidirectional level-shifting in mixed-voltage digital systems-targeting industrial, communications, and computing infrastructure.

FAQ

What is the maximum operating temperature range for the SN74CBTD3861DW?

The SN74CBTD3861DW is rated for operation from –40°C to +85°C ambient temperature. This industrial-grade range ensures reliable performance in embedded controllers, programmable logic systems, and factory automation equipment where thermal margins are constrained. The SOIC-24 package exhibits a θ_JA of 46°C/W, supporting continuous operation at full load within this envelope when mounted on standard FR-4 with adequate copper area.

Does the SN74CBTD3861DW support true bidirectional signal flow?

Yes, the SN74CBTD3861DW supports fully bidirectional signal flow between Port A and Port B with no direction control pin required. When OE is low, the 10 FET switches conduct equally in either direction-enabling seamless use in data buses, address lines, or control signals that change direction dynamically. Signal polarity, edge rate, and voltage swing are preserved without inversion or buffering.

Can the SN74CBTD3861DW be used for 3.3-V-to-5-V level shifting?

No-the SN74CBTD3861DW is designed specifically for 5-V-to-3.3-V level shifting via its internal diode-to-V_CC structure. Driving Port B with 3.3-V signals will not produce 5-V outputs at Port A. For reverse translation, a dedicated 3.3-V-to-5-V translator (e.g., TXB0108) or discrete solution is required. The device's absolute maximum ratings allow 3.3-V inputs safely, but no active up-shifting function exists.

Is the NC pin on the SN74CBTD3861DW electrically usable?

No, Pin 24 (NC) on the SN74CBTD3861DW has no internal connection and must remain unconnected on the PCB. It is not intended for grounding, heat sinking, or signal routing. TI's mechanical drawings confirm it is a true no-connect terminal; soldering or routing to this pin provides no functional benefit and risks mechanical stress or contamination during assembly.

What is the recommended PCB layout practice for minimizing noise on the SN74CBTD3861DW's V_CC and GND pins?

Place a 0.1-µF ceramic decoupling capacitor between V_CC (Pin 12) and GND (Pin 11) as close as possible to the device-ideally within 3 mm-with short, wide traces. Use a solid ground plane beneath the SOIC-24 footprint and avoid splitting the plane under the device. Route V_CC and GND traces directly to the capacitor pads, not daisy-chained; this reduces high-frequency impedance and suppresses switching noise coupling into adjacent channels.