Texas Instruments SN74CBT3244CDWR

Overview

SN74CBT3244CDWR from Texas Instruments is a high-speed TTL-compatible 8-bit FET bus switch organized as two independent 4-bit switches, featuring near-zero propagation delay (0.15 ns typical at 5 V), low ON-state resistance (3 Ω typical), and bidirectional signal flow. It supports 0–5-V signaling across multiple logic families (0.8 V to 5 V) and enables bus isolation in memory and USB interface applications.

For engineers reviewing the SN74CBT3244CDWR datasheet, SN74CBT3244CDWR pinout, SN74CBT3244CDWR application, or SN74CBT3244CDWR equivalent, key selection criteria include undershoot protection to −2 V, Ioff partial-power-down capability, low 5.5-pF OFF-state capacitance, and SOIC-20 packaging with 100% lead-free NIPDAU finish and Level-1 MSL rating.

Technical Context

The SN74CBT3244CDWR implements dual 4-bit FET-based analog/digital switches with independent OE control (1OE, 2OE), enabling flexible configuration as either two 4-bit or one 8-bit switch. Each switch channel features active undershoot-protection circuitry that maintains OFF-state integrity when A/B port voltages dip to −2 V.

It operates from 4 V to 5.5 V VCC, supports TTL- and CMOS-level control inputs, and delivers rail-to-rail data I/O compatibility (0–5.5 V). The Ioff specification ensures backflow current blocking during partial power-down, while latch-up immunity exceeds 100 mA per JESD 78 Class II.

Key Specifications

Pinout & Package

SN74CBT3244CDWR is housed in a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 2.65 mm max height, with 1.27 mm pitch and gull-wing leads. Pin 1 index located at top-left corner with notch marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3244CDWR, SN74CBTD3384CDW trades undershoot robustness and voltage flexibility for lower cost in 3.3-V-only systems, while PI3CH400LE prioritizes ultra-low capacitance over safety features - making SN74CBT3244CDWR the optimal choice for industrial bus isolation requiring −2 V tolerance and Ioff.

Availability

SN74CBT3244CDWR is available at Aetrix Electronics and suitable for USB interface design, memory interleaving, and industrial bus isolation requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for SN74CBT3244CDWR 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 high-reliability components.

The SN74CBT3244CDWR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital systems and analog-sensitive applications like USB and memory interfaces.

FAQ

What is the maximum undershoot voltage the SN74CBT3244CDWR can withstand on its A/B ports?

The SN74CBT3244CDWR provides active undershoot protection up to −2 V on both A and B ports, verified per datasheet Figure 2 and electrical characteristics table. This ensures the switch remains reliably OFF during negative transients, preventing false conduction or latch-up. The protection circuit senses the event and holds the internal FET gate in cutoff, independent of OE state. SN74CBT3244CDWR maintains this rating across its full operating temperature range (−40°C to 85°C).

Does the SN74CBT3244CDWR support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT3244CDWR supports partial-power-down via its Ioff feature, specified at 10 µA maximum when VCC = 0 V and I/O ports biased between 0–5.5 V. This blocks damaging back-current flow through the switch during power sequencing or hot-swap events. The design relies on internal transistor cutoff rather than external circuitry, and SN74CBT3244CDWR maintains high-impedance isolation even with VCC unpowered - critical for modular system architectures.

Can the SN74CBT3244CDWR be used for analog signal switching, and what limits its performance in that role?

Yes, the SN74CBT3244CDWR is explicitly qualified for analog applications per its datasheet Applications section. Its symmetric FET structure, absence of body diodes, and low 3 Ω ron ensure minimal THD and flat frequency response. Performance is limited primarily by Cio(ON) (14 pF), which introduces slight high-frequency roll-off above 500 MHz, and by the 5.5-V absolute maximum I/O voltage rating - SN74CBT3244CDWR must not be used with signals exceeding this threshold.

What is the recommended power-up sequence for the SN74CBT3244CDWR to ensure high-impedance state at startup?

To guarantee high-impedance during power-up, OE pins (1OE and 2OE) must be tied to VCC through a pullup resistor - minimum value determined by the driver's sink capability (typically ≤10 kΩ). This prevents floating OE states that could momentarily enable the switch before system control asserts. The SN74CBT3244CDWR datasheet specifies this requirement in the Ordering Information section, and failure to implement it risks bus contention or signal corruption at power-on reset.

Is the SN74CBT3244CDWR pin-compatible with other members of the CBT3244 family, such as SN74CBT3244CPWR or SN74CBT3244CDGVR?

Yes, all CBT3244 variants - including SN74CBT3244CDWR, SN74CBT3244CPWR, and SN74CBT3244CDGVR - share identical 20-pin functional pinouts and logic behavior. Differences are strictly in package type (SOIC vs. TSSOP vs. TVSOP), thermal performance, and moisture sensitivity level. SN74CBT3244CDWR uses SOIC-DW, offering highest thermal dissipation (θJA = 58°C/W) among the group, making it preferred for high-density or thermally constrained layouts.