Texas Instruments SN74CBT3244RGYR

Overview

SN74CBT3244RGYR from Texas Instruments is an octal FET bus switch organized as two independent 4-bit bidirectional low-impedance switches, featuring 5 Ω typical ON-state resistance, 6 pF typical OFF-state I/O capacitance, and sub-nanosecond propagation delay (0.25 ns typical), used for high-speed signal routing between microprocessors and peripherals in factory automation control boards.

For engineers reviewing the SN74CBT3244RGYR datasheet, SN74CBT3244RGYR pinout, SN74CBT3244RGYR application, or SN74CBT3244RGYR equivalent, key selection criteria include TTL/CMOS-compatible control inputs, 0–5 V data-level support, 200 MHz bandwidth capability, and VQFN-20 package thermal performance (RθJA = 37 °C/W).

Technical Context

The SN74CBT3244RGYR implements eight independent analog/digital signal paths using NMOS transmission-gate topology with active-low output-enable controls (1OE, 2OE). Each 4-bit group operates bidirectionally with near-zero propagation delay and flat on-resistance over temperature (5–7 Ω at VCC = 4.5 V).

It supports mixed-voltage signaling (0–5 V on I/Os) while maintaining TTL-compatible control thresholds (VIH = 2 V min, VIL = 0.8 V max) and draws only 50 µA maximum ICC at VCC = 5.5 V, enabling low-power bus isolation in multi-processor communication systems.

Key Specifications

Pinout & Package

VQFN-20 (RGY) package, 3.35 mm × 4.35 mm body, 0.4 mm pitch, exposed thermal pad; RoHS-compliant, MSL Level-1, peak reflow 260 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3244RGYR, SN74CBTD3384PWR adds dual-supply flexibility but increases layout complexity, while SN74LVC1G3157DCKR offers ultra-small size at the cost of scalability and bus-oriented functionality-neither matches the SN74CBT3244RGYR's combination of octal width, '244 pinout, and 5 V-only simplicity.

Availability

SN74CBT3244RGYR is available at Aetrix Electronics and suitable for factory automation control boards, building automation control boards, and multi-processor communications requiring stable component supply and industrial-grade thermal performance.

Supply support for SN74CBT3244RGYR 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and consumer markets since 1930.

The SN74CBT3244RGYR belongs to TI's CBT (Crosspoint Bus Transceiver) family, designed specifically for high-speed, low-distortion digital bus switching in industrial control and test instrumentation where timing integrity and signal fidelity are critical.

FAQ

What is the function of the 1OE and 2OE pins on the SN74CBT3244RGYR?

The 1OE and 2OE pins are active-low output-enable controls for the two independent 4-bit switch groups. When pulled low, each enables bidirectional conduction between its respective A and B ports; when high, it places those ports in high-impedance isolation. For safe power-up behavior, TI recommends tying both OE pins to VCC through pullup resistors. This ensures the SN74CBT3244RGYR starts in a disconnected state until firmware asserts the appropriate enable signal.

Can the SN74CBT3244RGYR operate with 3.3 V logic levels on its I/O pins while powered from a 5 V supply?

Yes, the SN74CBT3244RGYR supports 0–5 V signaling on all I/O pins (1A1–1B4, 2A1–2B4) regardless of VCC, which must be 4.5–5.5 V. This means 3.3 V CMOS outputs can drive the SN74CBT3244RGYR inputs directly, and the SN74CBT3244RGYR outputs will swing rail-to-rail within the 3.3 V domain when connected to a 3.3 V load. No level-shifting circuitry is required, making the SN74CBT3244RGYR ideal for mixed-voltage system integration.

What is the maximum continuous current per channel for the SN74CBT3244RGYR?

The SN74CBT3244RGYR supports a maximum continuous channel current of 128 mA, as specified in Absolute Maximum Ratings. However, for reliable operation within recommended conditions, TI specifies a maximum load current of ±64 mA per channel in Electrical Characteristics. Exceeding ±64 mA may increase on-resistance variation and thermal stress. The SN74CBT3244RGYR's 5 Ω typical ron ensures minimal voltage drop even at 64 mA (≤320 mV drop), preserving signal margins in high-speed digital applications.

Does the SN74CBT3244RGYR require external bypass capacitors, and if so, what value and placement is recommended?

Yes, TI mandates a 0.1 µF ceramic bypass capacitor between VCC and GND for the SN74CBT3244RGYR. It must be placed as close as possible to the VCC (pin 20) and GND (pin 10) terminals-ideally within 3 mm-to suppress high-frequency supply noise and prevent switching-induced ground bounce. This requirement is critical for maintaining sub-nanosecond propagation delay stability and preventing false triggering. The SN74CBT3244RGYR has only one VCC pin, so a single 0.1 µF capacitor suffices for full decoupling.

Is the SN74CBT3244RGYR pin-compatible with other packages in the SN74CBT3244 family, such as SOIC or TSSOP?

Yes-the SN74CBT3244RGYR shares identical pin functions and '244-type pinout with all SN74CBT3244 variants (e.g., DW, DB, PW), though physical dimensions and thermal characteristics differ. Pin numbering and signal mapping (e.g., 1OE = pin 1, VCC = pin 20) are consistent across SOIC-20, SSOP-20, TSSOP-20, and VQFN-20 packages. This allows direct migration from larger packages to the compact 3.35 mm × 4.35 mm RGY footprint without netlist or schematic changes-only PCB layout adaptation is required for the smaller pad geometry and exposed thermal pad.