Texas Instruments SN74CBTD3384CDBR

Overview

SN74CBTD3384CDBR from Texas Instruments is a 24-pin SSOP bidirectional FET bus switch IC with dual 5-bit configuration, 3 Ω typical ON-state resistance, −2 V undershoot protection on A/B ports, and integrated 5-V-to-3.3-V level shifting. It enables low-distortion signal gating in memory interleaving and bus isolation applications operating from 4.5 V to 5.5 V.

For engineers reviewing the SN74CBTD3384CDBR datasheet, SN74CBTD3384CDBR pinout, SN74CBTD3384CDBR application, or SN74CBTD3384CDBR equivalent, key selection criteria include its Ioff partial-power-down capability, 0.15 ns propagation delay, 5 pF OFF-state I/O capacitance, and support for 0–5 V signaling across 7 logic families (0.8 V to 5 V).

Technical Context

This device implements two independent 5-bit FET bus switches with separate OE controls (1OE, 2OE), enabling configurable 5-bit or 10-bit operation. Each switch uses low-threshold MOSFETs with active undershoot-protection circuitry that clamps A/B port voltages down to −2 V while maintaining OFF-state isolation.

The integrated VCC-series diode enables passive 5-V input to 3.3-V output level translation without external components. Control inputs accept TTL or 5-V/3.3-V CMOS logic, and Ioff ensures <10 µA backflow current during partial power-down, supporting hot-insertion and system-level power sequencing.

Key Specifications

Pinout & Package

SN74CBTD3384CDBR uses a 24-pin SSOP (Shrink Small-Outline Package) with 0.65 mm pitch, 7.9 mm × 6.6 mm body size, and 1.2 mm max height per JEDEC MO-150.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3384CDBR, the SOIC variant offers superior thermal performance for sustained high-current operation, while the TSSOP version delivers 30% smaller area at the cost of thermal headroom-making DBR optimal for balanced industrial density and reliability.

Availability

SN74CBTD3384CDBR is available at Aetrix Electronics and suitable for memory interleaving, bus isolation, and hot-swap backplane applications requiring stable component supply, long-term lifecycle continuity, and RoHS-compliant sourcing.

Supply support for SN74CBTD3384CDBR 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 SN74CBTD3384CDBR belongs to TI's CBTD family of high-speed FET bus switches, designed specifically for low-latency, mixed-voltage digital interconnects in industrial, telecom, and computing infrastructure.

FAQ

What is the maximum undershoot voltage the SN74CBTD3384CDBR can tolerate on its A/B ports?

The SN74CBTD3384CDBR tolerates up to −2 V undershoot on both A and B ports under all operating conditions. This is achieved via active undershoot-protection circuitry that senses negative transients and forces the internal FETs into a guaranteed OFF state, preventing unintended conduction and protecting downstream logic. The specification is verified per test conditions in the datasheet with VCC = 5.5 V and switch OFF.

Does the SN74CBTD3384CDBR support true bidirectional signal flow without direction control pins?

Yes, the SN74CBTD3384CDBR supports fully bidirectional signal flow with no direction control required. Its FET-based architecture provides symmetrical conduction between A and B ports when enabled by 1OE or 2OE. Signal polarity, amplitude, and timing are preserved in both directions, making it ideal for data buses, clock distribution, and analog signal routing where direction reversal occurs dynamically.

How does the integrated level-shifting diode in the SN74CBTD3384CDBR function?

The SN74CBTD3384CDBR integrates a diode in series with VCC to enable passive 5-V-to-3.3-V level shifting: when a 5-V signal drives an A-port pin, the diode drops ~1.7 V (typical), delivering ~3.3 V to the B port. This eliminates external components while maintaining rail-to-rail signal swing. The effect is most consistent at moderate frequencies; high-edge-rate signals may exhibit reduced translation due to parasitic capacitance.

What is the purpose of the Ioff feature in the SN74CBTD3384CDBR, and how is it implemented?

The Ioff feature in the SN74CBTD3384CDBR limits backflow current to ≤10 µA when VCC = 0 V and I/O pins are biased to 0–5.5 V, preventing damage during partial power-down. It is implemented via internal transistor biasing that disables all channel conduction paths while maintaining isolation. This enables safe hot-swap operation and multi-rail power sequencing without external isolation circuitry.

Can the SN74CBTD3384CDBR be used for analog signal switching, and what are its limitations?

Yes, the SN74CBTD3384CDBR supports analog signal switching due to its low 3 Ω ron, 5 pF Cio(OFF), and rail-to-rail VI/O range (0–5.5 V). Limitations include no guaranteed monotonicity above 10 MHz, potential THD increase near voltage rails due to FET nonlinearity, and absence of specified analog bandwidth or settling time-making it suitable for DC–10 MHz audio, sensor, and control signals but not RF or precision DAC/ADC interfaces.