SN74CBT6800CDBQR

Overview

The SN74CBT6800CDBQR is a 10-bit TTL-compatible FET bus switch manufactured by Texas Instruments. It operates within a VCC range of 4 V to 5.5 V and supports bidirectional data flow with near-zero propagation delay (typical 0.24 ns at 4 V). The device features low ON-state resistance (3 Ω typical) and low input/output capacitance (5.5 pF typical). It includes active undershoot protection for A and B ports up to -2 V and precharges the B port via a user-selectable bias voltage (BIASV) to minimize live-insertion noise. Packaged in a 24-pin DBQ (SSOP/QSOP) format, it functions across an operating temperature range of -40°C to +85°C.

Feature Summary

• Active undershoot protection circuitry on A and B ports ensures proper OFF state during undershoot events up to -2 V.
• B-port outputs are precharged by a user-selectable bias voltage (BIASV) to minimize signal distortion during live insertion and hot-plugging.
• Supports partial-power-down mode operation using Ioff feature to prevent damaging backflow current when powered down.
• Data and control inputs provide undershoot clamp diodes for enhanced signal integrity.

Applications

• PCI interface applications supporting PCI hot plug
• Memory interleaving systems
• Bus isolation circuits
• Low-distortion signal gating

Procurement Notes

Verify the specific ordering suffix 'DBQR' corresponds to the SSOP/QSOP tape-and-reel package configuration. Confirm that the 'C' designation aligns with the required commercial temperature range (-40°C to +85°C). Ensure design compatibility with the 24-pin pinout and check for any recent product change notifications or discontinuation notices from Texas Instruments prior to finalizing procurement.

Selection Notes

Select this component for high-speed digital and analog applications requiring low loading and minimal signal distortion. The device is suitable where bidirectional data flow and near-zero propagation delay are critical. Consider the BIASV pin functionality if live-insertion noise reduction is required. Ensure control inputs can be driven by TTL or 5-V/3.3-V CMOS outputs as specified.

Part Context

This part belongs to the Widebus family of high-speed FET bus switches from Texas Instruments. It is designed to replace traditional mechanical switches or slower electronic switches in high-density digital systems. The SN74CBT6800C variant specifically offers robust protection features against undershoot and supports partial-power-down modes, making it distinct from standard bus switches lacking these protections.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided source material.

FAQ

How does the SN74CBT6800C handle live-insertion noise?

The device minimizes live-insertion noise by precharging the B port to a user-selectable bias voltage (BIASV). This ensures that glitches produced during card insertion do not cross the input threshold region of receivers on the active bus.

What is the function of the Ioff feature?

The Ioff feature supports partial-power-down mode operation. It ensures that damaging current will not backflow through the device when it is powered down, providing isolation during power off.

Can the control inputs be driven by different logic families?

Yes, the control inputs can be driven by TTL or 5-V/3.3-V CMOS outputs, providing flexibility in system design.