Texas Instruments SN74CBT3244CDBR

Overview

SN74CBT3244CDBR from Texas Instruments is a high-speed TTL-compatible 8-bit FET bus switch organized as two independent 4-bit switches, featuring 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), and undershoot protection up to −2 V on A/B ports. It supports bidirectional 0–5-V signaling across 1.2-V to 5-V logic families and enables bus isolation in memory and USB interfaces.

For engineers reviewing the SN74CBT3244CDBR datasheet, SN74CBT3244CDBR pinout, SN74CBT3244CDBR application, or SN74CBT3244CDBR equivalent, key selection criteria include Ioff partial-power-down capability, low 5.5 pF OFF-state I/O capacitance, ±128 mA switch current rating, and SSOP-20 package compatibility with legacy board layouts.

Technical Context

The SN74CBT3244CDBR implements dual independent 4-bit FET transmission gates controlled by separate 1OE and 2OE inputs, each enabling bidirectional conduction between corresponding A and B port pairs when asserted low. Its active undershoot-protection circuitry monitors A/B port voltages and forces internal disable during −2 V transients to prevent false turn-on.

Designed for mixed-voltage system interfacing, the device accepts TTL- and CMOS-level control inputs (VIH = 2 V min, VIL = 0.8 V max) while supporting data I/Os across 0–5.5 V. The Ioff feature guarantees isolation during power-down by limiting backflow current to 10 µA when VCC = 0 V.

Key Specifications

Pinout & Package

SN74CBT3244CDBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.2 mm × 5.3 mm body size, and 1.2 mm max height. Pin 1 is marked by a beveled corner or index notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3244CDBR, SN74CBTD3384CDW adds dual-supply flexibility at the cost of transient resilience, while PI3CH480QS trades isolation and protection for marginal speed gain-making SN74CBT3244CDBR optimal for ruggedized, mixed-voltage bus gating.

Availability

SN74CBT3244CDBR is available at Aetrix Electronics and suitable for USB interface isolation, memory interleaving, and industrial bus isolation requiring stable component supply across automotive, industrial, and computing applications.

Supply support for SN74CBT3244CDBR 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 50 years of innovation in high-reliability interface solutions.

The SN74CBT3244CDBR belongs to TI's CBT (CrossBar Technology) bus switch family, engineered for zero-delay, low-distortion signal routing in mixed-voltage systems with stringent transient immunity requirements.

FAQ

What is the maximum undershoot voltage the SN74CBT3244CDBR can withstand on its A and B ports?

The SN74CBT3244CDBR provides active undershoot protection up to −2 V on both A and B ports, as verified in the absolute maximum ratings and undershoot characteristics section of the SCDS130A datasheet. This protection is implemented via internal sensing circuitry that forces the switch into a guaranteed OFF state during transient events, preventing unintended conduction. The SN74CBT3244CDBR maintains this specification across its full operating temperature range of −40°C to 85°C.

Does the SN74CBT3244CDBR support partial-power-down operation, and how does it behave when VCC = 0 V?

Yes, the SN74CBT3244CDBR supports partial-power-down via its Ioff feature. When VCC = 0 V, the device limits backflow current to 10 µA maximum (per electrical characteristics table), ensuring isolation between A and B ports even with live signals present. This behavior is confirmed in the "Ioff" parameter row and functional description, making the SN74CBT3244CDBR suitable for hot-swap and modular power architectures where subsystems power up/down independently.

What is the typical ON-state resistance of the SN74CBT3244CDBR, and how does it affect signal integrity?

The SN74CBT3244CDBR has a typical ON-state resistance (ron) of 3 Ω at VCC = 4.5 V and IO = 30 mA, as specified in the electrical characteristics table. This low ron ensures minimal voltage drop (<90 mV at 30 mA) and preserves signal amplitude across the switch path. Combined with 5.5 pF OFF-state capacitance and near-zero propagation delay, the SN74CBT3244CDBR maintains signal fidelity in high-speed digital and analog applications without requiring external termination or compensation.

Can the SN74CBT3244CDBR interface between 1.8-V and 5-V logic domains, and what are the voltage limits?

Yes, the SN74CBT3244CDBR supports bidirectional signaling between 1.8-V and 5-V logic domains. Its data I/Os operate from 0 V to 5.5 V, and control inputs accept TTL/CMOS levels (VIH ≥ 2 V, VIL ≤ 0.8 V) compatible with both 3.3-V and 5-V drivers. The device does not perform active level translation but relies on its wide VI/O range and low ron to pass signals transparently-verified in the "Data I/Os Support 0 to 5-V Signaling Levels" feature list and recommended operating conditions table for SN74CBT3244CDBR.

What package type and dimensions does the SN74CBT3244CDBR use, and is it compatible with standard SSOP footprints?

The SN74CBT3244CDBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.2 mm × 5.3 mm body size, and 1.2 mm maximum height, matching JEDEC MO-153 standards. Its pinout and mechanical dimensions align with industry-standard SSOP-20 footprints, enabling drop-in replacement in existing designs using SOIC or TSSOP variants-confirmed in TI's DB package drawing MPDS006C and tape-and-reel documentation for SN74CBT3244CDBR.