Texas Instruments SN74CBT6800CPW

Overview

SN74CBT6800CPW from Texas Instruments is a 10-bit bidirectional FET bus switch with TTL-compatible control, 3 Ω typical ON-state resistance, −2 V undershoot protection on A/B ports, and B-port precharge via BIASV for live-insertion noise suppression in PCI hot-plug systems.

For engineers reviewing the SN74CBT6800CPW datasheet, SN74CBT6800CPW pinout, SN74CBT6800CPW application, or SN74CBT6800CPW equivalent, key selection criteria include its 0.15 ns propagation delay at 5 V, 5.5 pF OFF-state I/O capacitance, Ioff partial-power-down support, 4–5.5 V VCC operation, and TSSOP-24 package compatibility with hot-swap backplane interfaces.

Technical Context

This device implements a 10-channel analog/digital signal gate using low-ron FETs, with independent undershoot-protection circuitry per A/B port that clamps to −2 V and maintains OFF-state integrity during voltage transients. Its BIASV-biased precharge path (via ~10 kΩ equivalent) actively holds B-port nodes near receiver threshold to suppress live-insertion glitches.

The SN74CBT6800CPW features true bidirectional signal flow with near-zero propagation delay (0.15 ns typ. at VCC = 5 V), supports 0–5 V signaling across 0.8 V to 5 V logic families, and guarantees isolation during power-down via Ioff, preventing backflow current when VCC = 0 V.

Key Specifications

Pinout & Package

TSSOP-24 package (PW), 7.9 mm × 4.5 mm × 1.2 mm max height, 0.65 mm lead pitch, moisture sensitivity level 1, RoHS-compliant NIPDAU finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT6800CPW, SN74CBTD6800CPW adds built-in termination but sacrifices I/O capacitance performance, while SN74CB3Q3257PWR offers multiplexing flexibility at the cost of missing hot-plug–specific protections and scalability.

Availability

SN74CBT6800CPW is available at Aetrix Electronics and suitable for PCI hot-plug interfaces, memory interleaving systems, hot-swap backplane isolation, and legacy bus signal gating requiring stable component supply and long-term lifecycle continuity.

Supply support for SN74CBT6800CPW 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, precision, and industrial-grade performance.

The SN74CBT6800CPW belongs to TI's Widebus™ family of high-speed bus switches, engineered specifically for hot-plug, live-insertion, and partial-power-down applications in computing, telecom, and industrial backplane architectures.

FAQ

What is the maximum undershoot voltage the SN74CBT6800CPW can withstand on its A and B ports?

The SN74CBT6800CPW provides active undershoot protection up to −2 V on both A and B ports, as verified in the absolute maximum ratings and functional description. This clamping behavior ensures the switch remains reliably OFF during transient negative excursions, such as those occurring during live card insertion. The protection circuit senses the event and maintains isolation without requiring external components. SN74CBT6800CPW achieves this while maintaining full compatibility with standard 5 V PCI signaling environments.

How does the BIASV pin function in the SN74CBT6800CPW during hot-plug events?

The BIASV pin on the SN74CBT6800CPW supplies a user-defined bias voltage (0 V to VCC) that precharges the B-port I/Os through an internal ~10 kΩ path when the device is disabled (ON = high) or powered down (VCC = 0 V). During hot-plug, this precharge holds B-port nodes near the input threshold of downstream receivers-typically 2.0–2.4 V for 3.3 V LVTTL-so insertion transients do not cross the logic threshold region. SN74CBT6800CPW thus prevents false switching and bus contention without external circuitry.

Does the SN74CBT6800CPW support partial-power-down operation, and how is it implemented?

Yes, the SN74CBT6800CPW fully supports partial-power-down operation via its Ioff feature. When VCC = 0 V, the device limits backflow current to ≤10 µA even with up to 5.5 V applied to I/O pins, preventing damage to powered-down sections of the system. This capability is explicitly characterized in the electrical specifications and enables safe hot-swap of modules in mixed-power-domain systems. SN74CBT6800CPW maintains high-impedance isolation under these conditions without external supervision.

What is the typical ON-state resistance of the SN74CBT6800CPW, and how does it affect signal integrity?

The SN74CBT6800CPW has a typical ON-state resistance (ron) of 3 Ω at VCC = 4.5 V and IO = 30 mA, with a maximum of 6 Ω across temperature and voltage. This low ron minimizes voltage drop across the switch (e.g., <180 mV at 60 mA), preserving logic high/low margins and reducing IR loss in high-current data paths. It also contributes to the device's 0.15 ns propagation delay and 5.5 pF OFF-state capacitance-key factors in maintaining signal edge fidelity. SN74CBT6800CPW delivers this performance while remaining compatible with standard 5 V bus architectures.

Can the SN74CBT6800CPW interface between different logic voltage domains, such as 1.8 V and 3.3 V?

Yes, the SN74CBT6800CPW supports 0–5 V signaling on its A and B data I/Os, making it compatible with 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, and 5 V logic families without level-shifting circuitry. Its control inputs accept TTL or 5 V/3.3 V CMOS levels, and VCC operates from 4 V to 5.5 V-decoupled from I/O voltage constraints. This allows seamless bridging of mixed-voltage subsystems. SN74CBT6800CPW achieves this while retaining its undershoot protection, BIASV precharge, and Ioff features across all supported I/O ranges.