Texas Instruments SN74CBT3245ARGYR

Overview

SN74CBT3245ARGYR from Texas Instruments is an octal FET bus switch IC designed for high-speed TTL-compatible bidirectional signal routing between two 8-bit data ports (A and B). It features 5-Ω on-state resistance, 0.25 ns typical propagation delay at 5 V, and operates from −40°C to 85°C with supply voltage 4–5.5 V. It is used in address/data bus isolation, hot-swap interface buffering, and level-translating I/O expansion.

For engineers reviewing the SN74CBT3245ARGYR datasheet, SN74CBT3245ARGYR pinout, SN74CBT3245ARGYR application, or SN74CBT3245ARGYR equivalent, key selection criteria include on-resistance matching, OE-controlled bidirectional switching timing, thermal performance in QFN packages, and compatibility with standard '245-type board layouts.

Technical Context

The SN74CBT3245ARGYR implements eight independent analog FET switches controlled by a single active-low output-enable (OE) input. When OE is low, all A–B paths conduct with minimal R_ON (5–7 Ω), enabling near-transparent signal pass-through; when OE is high, both ports enter high-impedance states. Its architecture avoids internal latches or logic, supporting true bidirectional DC-coupled signal flow without direction control pins.

Designed for 5-V TTL systems, it accepts VIH ≥ 2 V and VIL ≤ 0.8 V, ensuring robust noise margin. The RGY package's 37°C/W θ_JA enables stable operation under sustained 128 mA channel current per switch, with input clamp current rated to −50 mA for transient protection.

Key Specifications

Pinout & Package

VQFN-20 (RGY) package: 3.5 mm × 4.5 mm, 0.5 mm pitch, 1 mm max height, exposed thermal pad. Pin 1 index located at top-left corner (quadrant Q1) per JEDEC MO-220.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3245ARGYR, SN74CBTD3384ADBR offers wider voltage range but less precise timing control, while 74LVC245APW provides stronger drive but lacks true bidirectional transparency and adds direction logic overhead.

Availability

SN74CBT3245ARGYR is available at Aetrix Electronics and suitable for industrial PLC backplanes, PCIe slot buffering, and memory-mapped FPGA configuration requiring stable component supply and long-term lifecycle support.

Supply support for SN74CBT3245ARGYR 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 over 90 years of innovation in industrial, automotive, and communications markets.

The SN74CBT3245A product line delivers high-speed, low-R_ON FET bus switches optimized for bidirectional signal isolation in 5-V TTL systems, targeting applications demanding minimal propagation delay and seamless '245-pinout compatibility.

FAQ

What is the maximum continuous current rating per channel for SN74CBT3245ARGYR?

The SN74CBT3245ARGYR supports a continuous channel current of 128 mA per switch. This rating ensures reliable conduction under sustained load conditions without thermal runaway, provided the junction temperature remains within −40°C to 125°C limits. Derating is required above 85°C ambient, based on the RGY package's 37°C/W θ_JA.

Does SN74CBT3245ARGYR support 3.3-V logic inputs?

No, SN74CBT3245ARGYR is specified for TTL-compatible 5-V operation only, with VIH ≥ 2.0 V and VIL ≤ 0.8 V. While it may function with 3.3-V inputs in some cases, TI does not guarantee performance outside the recommended operating conditions (VCC = 4–5.5 V, VI = 0–VCC). For 3.3-V systems, consider SN74CBTD3384ADBR instead.

How should the OE pin be handled during power-up to ensure safe default state?

To ensure high-impedance state during power-up or power-down, OE must be tied to VCC via a pull-up resistor. TI specifies the minimum resistor value based on the driver's current-sinking capability; a 10-kΩ resistor is commonly used. Leaving OE floating risks undefined switching behavior and potential bus contention.

Is SN74CBT3245ARGYR pin-compatible with standard 74LS245 devices?

Yes, SN74CBT3245ARGYR uses the standard '245-type pinout across DB, DBQ, DGV, DW, PW, and RGY packages. Pin assignments for A1–A8, B1–B8, OE, VCC, and GND match industry-standard octal transceivers, enabling direct PCB footprint reuse without layout changes.

What is the significance of the NC pin (Pin 20) in the RGY package?

Pin 20 in the SN74CBT3245ARGYR RGY package is designated NC (No internal connection). It must remain unconnected - neither grounded nor tied to VCC. Using it as a thermal pad anchor or ground tie violates TI's mechanical specifications and may compromise thermal performance or cause electrical malfunction.