Texas Instruments SN74CBT3306DR

Overview

SN74CBT3306DR from Texas Instruments is a dual FET bus switch IC with independent 5-Ω on-state resistance switches, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and operation across −40°C to 85°C. It enables bidirectional signal routing in low-voltage data buses, such as between microcontroller GPIOs and peripheral I²C/SPI lines.

For engineers reviewing the SN74CBT3306DR datasheet, SN74CBT3306DR pinout, SN74CBT3306DR application, or SN74CBT3306DR equivalent, key selection criteria include on-resistance matching (5–7 Ω), sub-1 ns propagation delay (tpd = 0.25 ns at VCC = 5 V), OE-controlled isolation, and SOIC-8 thermal performance (θJA = 97°C/W).

Technical Context

The SN74CBT3306DR implements two independent single-pole single-throw (SPST) analog switches using NMOS pass transistors with integrated level-shifting circuitry. Each switch connects A and B ports when its dedicated OE input is logic low (≤0.8 V), and presents high-impedance isolation (>10⁹ Ω) when OE is high (≥2 V).

It operates from 4 V to 5.5 V supply, supports rail-to-rail analog/digital signals up to 7 V (VI/VO range), and delivers <1 ns enable/disable timing (ten = 1.8 ns, tdis = 1 ns at VCC = 5 V) with minimal capacitive loading (Cio(OFF) = 4 pF, Ci = 3 pF).

Key Specifications

Pinout & Package

SN74CBT3306DR is housed in an 8-pin SOIC (D) package (5.3 mm × 6.2 mm, 1.75 mm max height), compliant with JEDEC MS-012AA, with gull-wing leads and RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3306DR, SN74CBTD3306DR adds bus-hold functionality at the cost of higher quiescent current, while 74LVC2G66DP,125 offers footprint reduction and wider voltage flexibility but lacks native TTL-level compatibility and higher on-resistance.

Availability

SN74CBT3306DR is available at Aetrix Electronics and suitable for industrial control interfaces, embedded test instrumentation, and mixed-voltage peripheral interconnects requiring stable component supply and long-term sourcing continuity.

Supply support for SN74CBT3306DR 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 logic and interface solutions.

The SN74CBT3306DR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for low-latency, low-distortion signal routing in high-speed digital systems where timing predictability and voltage translation are critical.

FAQ

What is the maximum signal voltage that can be passed through SN74CBT3306DR?

The SN74CBT3306DR supports input/output signal voltages from −0.5 V to 7 V, independent of VCC. This allows it to safely pass overvoltage transients, hot-swap signals, or mixed-rail logic levels (e.g., 3.3-V signals into a 5-V system) without damage or clamping, provided the absolute maximum ratings (e.g., VI < 7 V) are observed. The SN74CBT3306DR does not include internal ESD protection diodes to VCC or GND beyond its specified clamp-current limits.

Can SN74CBT3306DR operate with a 3.3-V supply?

No - the SN74CBT3306DR requires a minimum VCC of 4 V per the recommended operating conditions. At 3.3 V, the internal level-shifter circuitry fails to fully enhance the pass transistors, resulting in elevated and unstable on-resistance (>20 Ω) and potential signal degradation. For 3.3-V operation, consider alternatives like the 74LVC2G66 or SN74AUC2G66, which are explicitly characterized down to 1.65 V.

Is SN74CBT3306DR pin-compatible with SN74CBT3306D?

Yes - SN74CBT3306DR and SN74CBT3306D share identical SOIC-8 (D) package dimensions, pinout, and electrical specifications. The "R" suffix denotes tape-and-reel packaging; both parts use the same CU306 top-side marking and have identical thermal and switching characteristics. No PCB layout changes are required when substituting SN74CBT3306DR for SN74CBT3306D.

Does SN74CBT3306DR support bidirectional signal flow?

Yes - each switch in the SN74CBT3306DR is fully bidirectional: signals pass equally well from A to B or B to A when enabled. This is inherent to its FET-based architecture with no intrinsic directionality. The device is commonly used to isolate bidirectional buses like I²C, SMBus, or JTAG TDI/TDO lines, where signal polarity and direction change dynamically during operation.

What is the thermal performance of SN74CBT3306DR in its SOIC package?

The SN74CBT3306DR in SOIC-8 (D) package has a junction-to-ambient thermal resistance (θJA) of 97°C/W under standard JEDEC test conditions. With a maximum continuous channel current of 128 mA and typical on-resistance of 6 Ω, power dissipation remains below 100 mW - keeping junction temperature rise under 10°C above ambient even at full load, assuming adequate PCB copper area and airflow.