Texas Instruments SN74CBT3244DBQR

Overview

SN74CBT3244DBQR 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 0.25 ns typical propagation delay-enabling high-speed signal routing in microprocessor-peripheral interconnects.

For engineers reviewing the SN74CBT3244DBQR datasheet, SN74CBT3244DBQR pinout, SN74CBT3244DBQR application, or SN74CBT3244DBQR equivalent, key selection criteria include TTL/CMOS-compatible control inputs, 4.5 V to 5.5 V VCC operation, bidirectional zero-delay switching, and SSOP-20 package compatibility with standard '244 pinout layouts.

Technical Context

The SN74CBT3244DBQR implements eight independent analog/digital signal paths using NMOS transmission-gate topology, with two active-low output-enable (1OE, 2OE) controls isolating respective 4-bit A↔B channels. Its near-zero propagation delay arises from low r_on–C_io product (5 Ω × 6 pF), supporting up to 200 MHz data rates without signal distortion.

Each channel operates bidirectionally with rail-to-rail voltage tolerance (0 V to 5 V on I/O pins), while maintaining CMOS/TTL-compatible OE thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2 V) and consuming only 50 µA max ICC at 5.5 V-making it suitable for hot-swap-capable, low-power digital backplanes and test instrumentation interfaces.

Key Specifications

Pinout & Package

SN74CBT3244DBQR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 8.65 mm × 3.90 mm body size, and 2.0 mm max height-designed for high-density PCB layouts while maintaining mechanical robustness and thermal performance (R_θJA = 68 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3244DBQR, SN74CBTD3384DBQR offers greater bit width but sacrifices independent dual-group OE control and 5 V VCC support, while SN74LVC1G3157DCKR provides compact single-channel switching at the cost of scalability and pinout compatibility-making SN74CBT3244DBQR uniquely suited for legacy '244-replacement and dual 4-bit bus isolation.

Availability

SN74CBT3244DBQR is available at Aetrix Electronics and suitable for multi-processor communications, test and measurement systems, and factory automation control boards requiring stable component supply and long-term obsolescence management.

Supply support for SN74CBT3244DBQR 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 specializing in analog and embedded processing technologies, with over 50 years of leadership in logic, interface, and signal-chain innovation.

The SN74CBT3244DBQR belongs to TI's CBT (Crossbar Bus Transceiver) family-designed specifically for high-speed, low-distortion digital signal routing in industrial control, instrumentation, and computing infrastructure.

FAQ

What is the maximum operating frequency supported by the SN74CBT3244DBQR?

The SN74CBT3244DBQR supports data rates up to 200 MHz due to its low 5 Ω typical ON-state resistance and 6 pF typical OFF-state I/O capacitance, which together yield a minimal r_on–C_io time constant. This enables clean signal edges and low jitter in high-speed parallel bus applications such as microprocessor-peripheral interconnects and JTAG boundary-scan chains-provided PCB layout follows TI's recommended trace-length and bypass-capacitor guidelines.

Is the SN74CBT3244DBQR compatible with 3.3 V control logic?

Yes, the SN74CBT3244DBQR accepts TTL and 5 V/3.3 V CMOS-compatible control inputs: V_IL ≤ 0.8 V and V_IH ≥ 2 V over the full –40°C to +85°C operating range. This allows direct interfacing with 3.3 V microcontrollers or FPGAs without level-shifting circuitry-even when VCC is operated at 5 V, as confirmed in Section 6.3 (Recommended Operating Conditions) of the official datasheet.

Does the SN74CBT3244DBQR require external pull-up resistors on OE pins?

Yes-TI recommends tying both 1OE and 2OE to VCC through pull-up resistors to ensure high-impedance state during power-up or power-down. The minimum resistor value depends on the driver's current-sinking capability, but typical values range from 4.7 kΩ to 10 kΩ. This prevents unintended bus connections before system initialization completes, as detailed in Section 8.4 (Device Functional Modes) of the SN74CBT3244DBQR datasheet.

Can the SN74CBT3244DBQR interface between 3.3 V and 5 V systems?

Yes-the SN74CBT3244DBQR supports 0 V to 5 V signaling on all I/O pins (1A1–1B4, 2A1–2B4) regardless of VCC voltage (4.5 V to 5.5 V). This allows bidirectional voltage translation: a 3.3 V microcontroller can safely drive and read signals from a 5 V peripheral through the switch, with no level shifters needed. This capability is explicitly stated in the "Data I/Os Support 0- to 5-V Signaling Levels" feature list.

What is the thermal performance of the SN74CBT3244DBQR in SSOP-20 package?

The SN74CBT3244DBQR in DBQ (SSOP-20) package has a junction-to-ambient thermal resistance (R_θJA) of 68 °C/W, as specified in Section 6.4 (Thermal Information) of the datasheet. With its 50 µA max ICC and low r_on, self-heating is minimal-typically less than 1°C above ambient at full 8-channel conduction. For sustained high-current operation (>64 mA per channel), TI recommends verifying board-level copper area and airflow per the layout guidelines in Section 11.