Texas Instruments SN74CBTD3861DWR

Overview

SN74CBTD3861DWR 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 control inputs (VIH = 2 V, VIL = 0.8 V), and single OE-enabled switching. Used in mixed-voltage memory expansion and processor peripheral interfaces.

For engineers reviewing the SN74CBTD3861DWR datasheet, SN74CBTD3861DWR pinout, SN74CBTD3861DWR application, or SN74CBTD3861DWR equivalent, key selection criteria include its 5-Ω Ron, 0.35 ns propagation delay, ±1 µA ICC, 24-pin SOIC-DW package, and verified level-shifting behavior under 4.5–5.5 V supply conditions.

Technical Context

The SN74CBTD3861DWR implements a single 10-bit bidirectional analog switch array using NMOS FETs with integrated VCC-referenced clamping diodes to enable 5-V input → 3.3-V output level translation. Its OE-controlled architecture provides high-impedance isolation when disabled, with no internal latching or direction control logic.

Switch operation relies on low-threshold NMOS conduction with on-resistance specified at 5 Ω (typ) under 30 mA current and 4.5 V VCC. Propagation delay is RC-limited (tpd = 0.35 ns typical), and timing parameters ten (2.6–10 ns) and tdis (1–6 ns) are defined relative to OE transitions - confirming fast enable/disable response without internal buffering.

Key Specifications

Pinout & Package

SN74CBTD3861DWR uses a 24-pin SOIC (DW) package measuring 15.4 mm × 7.5 mm × 2.35 mm (JEDEC MS-013), with 1.27 mm pitch and gull-wing leads. Pin 1 is located at top-left corner with index marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3861DWR, SN74CBT3244DWR offers lower Ron but no level-shifting, making it viable only in uniform-voltage systems; SN74LVC1G3157DCKR trades bus width and pin compatibility for ultra-small footprint - neither serves as a drop-in replacement, but both address adjacent signal-routing needs in compact or single-line designs.

Availability

SN74CBTD3861DWR is available at Aetrix Electronics and suitable for industrial control systems, legacy hardware upgrades, and embedded data acquisition requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74CBTD3861DWR 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 logic solutions with over 50 years of innovation in high-reliability interface and signal-path components.

The SN74CBTD3861DWR belongs to TI's 74CBT family of FET bus switches, engineered specifically for low-latency, low-power, mixed-voltage interconnect in industrial, computing, and communications infrastructure.

FAQ

What is the maximum continuous current rating per channel for the SN74CBTD3861DWR?

The SN74CBTD3861DWR supports a maximum continuous channel current of 128 mA per switch path, as specified in its absolute maximum ratings. This rating applies under recommended operating conditions (VCC = 4.5–5.5 V, TA = –40°C to +85°C) and assumes proper PCB thermal management. Exceeding this current may degrade Ron stability or accelerate wear-out mechanisms in the NMOS FET structure.

Does the SN74CBTD3861DWR require external pull-up resistors on its control inputs?

No, the SN74CBTD3861DWR does not require external pull-up resistors on its OE input because its TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) allow direct connection to standard 5-V logic outputs. However, TI recommends tying all unused control inputs to VCC or GND to prevent floating states that could cause erratic switching or increased ICC.

Can the SN74CBTD3861DWR be used for 3.3-V-to-5-V level shifting?

No, the SN74CBTD3861DWR is designed specifically for 5-V-to-3.3-V level shifting via its integrated VCC-referenced clamp diode. Driving 3.3-V signals into port A will not produce valid 5-V outputs at port B, as the internal diode structure and Ron characteristics are optimized for forward translation only. Reverse-direction translation requires a separate device such as the SN74AVC4T245.

What is the thermal resistance (θJA) of the SN74CBTD3861DWR in its SOIC-DW package?

The SN74CBTD3861DWR in the SOIC-DW package has a junction-to-ambient thermal resistance (θJA) of 46°C/W, as documented in the absolute maximum ratings table. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad, 2 oz Cu). Actual thermal performance may vary based on PCB layout, airflow, and nearby heat sources - derating is advised above 70°C ambient.

Is the SN74CBTD3861DWR pin-compatible with other members of the 74CBT family?

The SN74CBTD3861DWR shares the same 24-pin SOIC-DW footprint and pinout with SN74CBT3244DWR and SN74CBT3245DWR, but functional differences exist: SN74CBTD3861DWR includes level-shifting diodes and a single OE, whereas SN74CBT3244DWR has dual OE controls and no level-shifting. Thus, mechanical compatibility exists, but electrical substitution requires verification of control logic and voltage-domain requirements.