Texas Instruments SN74CBT3861DBQR

Overview

SN74CBT3861DBQR from Texas Instruments is a 10-bit FET bus switch IC with 5-Ω on-state resistance, TTL-compatible input levels, and single OE control enabling/disabling all channels simultaneously. It operates from 4 V to 5.5 V over –40°C to 85°C and is used in high-speed data path isolation for memory expansion, peripheral multiplexing, and hot-swap I/O buffering.

For engineers reviewing the SN74CBT3861DBQR datasheet, SN74CBT3861DBQR pinout, SN74CBT3861DBQR application, or SN74CBT3861DBQR equivalent, key selection criteria include on-resistance matching across A/B ports, propagation delay under 0.35 ns at 4 V, OE-controlled bidirectional isolation, and SSOP-24 thermal performance (θ_JA = 61°C/W).

Technical Context

This device implements ten independent NMOS transmission gates controlled by a single active-low output-enable (OE) signal. When OE is low, each A_n–B_n pair forms a low-impedance bidirectional path; when OE is high, both ports enter high-impedance states with <5 pF off-capacitance.

It uses TTL-level compatible inputs (V_IL ≤ 0.8 V, V_IH ≥ 2 V) and supports rail-to-rail analog/digital signal switching up to 128 mA per channel. The internal FET structure ensures latch-up immunity exceeding 250 mA per JESD 17.

Key Specifications

Pinout & Package

SN74CBT3861DBQR is housed in a 24-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.9 mm × 6.2 mm body size, and 1.2 mm max height. The package features no internal connection (NC) on Pin 1 and Pin 24, and exposes GND (Pin 11) and V_CC (Pin 12) adjacent to OE (Pin 13) for low-noise enable control routing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3384DBQR and 74LVC4066PW, SN74CBT3861DBQR delivers optimal balance of channel density, on-resistance, and single-supply simplicity for 5 V bus isolation-requiring no external level shifters or multiple ICs to achieve full 10-bit coverage.

Availability

SN74CBT3861DBQR is available at Aetrix Electronics and suitable for industrial control panels, test instrumentation interfaces, and embedded memory subsystems requiring stable component supply and long-term manufacturability.

Supply support for SN74CBT3861DBQR 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 SN74CBT3861DBQR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered specifically for low-latency, low-distortion digital bus switching in industrial and communications infrastructure where signal fidelity and timing predictability are critical.

FAQ

What is the maximum continuous current rating per channel for SN74CBT3861DBQR?

The SN74CBT3861DBQR supports a continuous channel current of 128 mA per A–B path, verified under recommended operating conditions (V_CC = 4 V to 5.5 V, T_A = –40°C to 85°C). This rating ensures reliable operation in high-drive applications such as memory bus termination and peripheral driver buffering without thermal derating at ambient temperatures below 70°C. Exceeding this limit risks permanent damage per absolute maximum ratings.

Does SN74CBT3861DBQR support bidirectional signal flow between Port A and Port B?

Yes, SN74CBT3861DBQR provides fully bidirectional signal conduction when OE is low - meaning data can pass equally well from A1→B1 or B1→A1 with identical electrical characteristics. This behavior is inherent to its NMOS transmission gate architecture and is confirmed in the functional table and logic diagram. No direction control pins or external biasing are required.

Can SN74CBT3861DBQR be operated from a 3.3 V supply?

No, SN74CBT3861DBQR is not rated for 3.3 V operation. Its recommended operating supply range is 4 V to 5.5 V, and the absolute minimum V_CC is –0.5 V (non-operational). Attempting to power SN74CBT3861DBQR at 3.3 V will result in undefined switching behavior, increased r_on, and potential failure to meet timing specifications. For 3.3 V systems, consider TI's SN74CBTD3384DBQR or similar dual-supply alternatives.

What is the significance of the NC pins on SN74CBT3861DBQR?

SN74CBT3861DBQR has NC (No Connection) pins at Pin 1 and Pin 24 - these pins have no internal bond wires or silicon connections. They must remain unconnected in the PCB layout; grounding or driving them may introduce parasitic coupling or violate JEDEC-compliant footprint requirements. TI's DBQ package drawing confirms these pins serve only mechanical alignment and thermal relief functions.

How does the latch-up immunity specification apply to SN74CBT3861DBQR in real-world designs?

SN74CBT3861DBQR exceeds 250 mA latch-up immunity per JESD 17, meaning it withstands transient current injection events - such as ESD discharges or hot-swap surges - without entering destructive thyristor-mode conduction. This is validated across process corners and temperature extremes, making SN74CBT3861DBQR suitable for ruggedized I/O protection in factory automation and field-deployable equipment where accidental shorts or connector mating arcs may occur.