SN74CBT6800CDWR

Overview

The SN74CBT6800CDWR is a high-speed TTL-compatible FET bus switch featuring 10-bit bidirectional data flow within a 24-pin SOIC (DW) package. It operates on a supply voltage range of 4 V to 5.5 V and supports data I/O levels from 0 V to 5 V, including 0.8-V, 1.2-V, 1.5-V, 1.8-V, 2.5-V, 3.3-V, and 5-V signaling. The device provides low ON-state resistance with a typical value of 3 Ω at VCC = 4.5 V and near-zero propagation delay of approximately 0.15 ns at VCC = 5 V. It incorporates active undershoot protection for off-isolation up to −2 V and precharges B-port outputs via the BIASV pin to minimize signal distortion during live insertion.

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 the user-selectable bias voltage (BIASV) to minimize signal distortion during live insertion and hot-plugging.
• Supports partial-power-down mode operation using the Ioff feature to prevent damaging backflow current when powered down.
• Data and control inputs provide undershoot clamp diodes, allowing control inputs to be driven by TTL or 5-V/3.3-V CMOS outputs.

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 'CDWR' corresponds to the SOIC-24 tape-and-reel configuration. Confirm that the 'C' designation indicates the specific device variant with active undershoot protection and BIASV functionality. Ensure the procurement documentation matches the manufacturer's part number exactly to avoid confusion with similar widebus family members lacking these features.

Selection Notes

Select this component when designing systems requiring low propagation delay and minimal signal loading for high-speed digital buses. The inclusion of the BIASV pin makes it suitable for environments where live insertion noise must be mitigated. Verify that the control logic can drive the required input thresholds and that the operating temperature range of -40°C to 85°C aligns with the system requirements.

Part Context

This device belongs to Texas Instruments' Widebus family of high-speed FET bus switches. It is designed to replace traditional mechanical switches or slower electronic switches in high-performance digital systems. The SN74CBT6800C variant specifically adds active undershoot protection compared to earlier iterations, enhancing reliability in dynamic bus environments.

Replacement Considerations

SN74CBT6800CDW (Tube packaging)

FAQ

How does the BIASV pin function during power-off?

When the device is powered down (VCC = 0 V) or in the OFF state, the B port is precharged to the BIASV voltage through an equivalent 10-kΩ resistor.

What is the purpose of the Ioff feature?

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