UCC5673PWPTR

Overview

The UCC5673PWPTR is a multimode SCSI terminator manufactured by Texas Instruments, designed for SPI-3 and Ultra2/Ultra160 compliant systems. It integrates both single-ended (SE) and low voltage differential (LVD) termination networks into a monolithic component. The device operates on a TRMPWR supply ranging from 2.7V to 5.25V. In LVD mode, the typical supply current is 35mA, while SE mode draws 25mA. The device features automatic mode selection based on the DIFSENS signal level: below 0.5V selects SE, between 0.7V and 1.9V selects LVD, and above 2.4V enters high impedance disconnect mode. It utilizes a 28-pin TSSOP package.

Feature Summary

• Automatically detects and switches between Single Ended and Low Voltage Differential termination modes based on bus signals.
• Integrates complete termination networks for up to nine data/control lines within a single chip.
• Includes built-in noise filtering and delay mechanisms to prevent false mode changes during bus transitions.
• Supports High Impedance Disconnect state when High Voltage Differential devices are detected on the bus.

Applications

• Termination for SCSI Parallel Interface (SPI-3) buses
• Ultra2 (SPI-2 LVD) and Ultra3/Ultra160 compliant storage systems
• Multi-mode active termination in mixed SE/LVD SCSI environments

Procurement Notes

Verify that the ordering suffix PWPTR corresponds to the specific tape-and-reel packaging configuration required for automated assembly processes. Confirm that the component revision matches the SLUS438 datasheet specifications to ensure compatibility with existing design parameters. Cross-reference the manufacturer's latest documentation to validate any potential updates to pinout or electrical characteristics before finalizing procurement orders.

Selection Notes

Select this component for designs requiring compliance with SPI-3 standards where mixed SE and LVD devices coexist on the same bus. Ensure the PCB layout accommodates the thermal requirements of the TSSOP package, specifically connecting the HS/GND pins to ground planes. Verify that the system power supply remains within the 2.7V to 5.25V range to maintain proper regulator operation and termination accuracy.

Part Context

This part belongs to the UCC5673 family of multimode SCSI terminators produced by Texas Instruments. It serves as a critical interface component for managing signal integrity at the ends of SCSI chains. The device simplifies board design by replacing discrete resistor networks with an integrated solution capable of handling multiple SCSI signaling standards dynamically.

Replacement Considerations

No public confirmed substitute part numbers are available in the provided documentation.

FAQ

How does the UCC5673 determine the termination mode?

The device monitors the voltage on the DIFSENS pin. If the voltage is below 0.5V, it activates Single Ended mode. Between 0.7V and 1.9V, it switches to Low Voltage Differential mode. Above 2.4V, it enters a high impedance disconnect state.

What is the purpose of the DIFFB pin?

The DIFFB pin receives the filtered DIFSENS signal through a 50Hz noise filter. It is used by internal comparators to detect valid mode changes and prevent false triggering due to bus noise.

How should the HS/GND pins be handled in the PCB layout?

The HS/GND pins must be connected to large ground area PC board traces or feed-throughs connecting to the ground plane layer. This facilitates heat dissipation from the die to reduce junction temperature.