UCC5628FQP

Overview

The UCC5628FQP is a multimode SCSI terminator manufactured by Texas Instruments, designed for seamless integration into low-voltage differential (LVD) and single-ended (SE) parallel interfaces. It automatically detects the bus type via the DIFFB pin and switches termination modes accordingly. The device supports SCSI-1 through Ultra320 standards and operates within a supply voltage range of 2.7 V to 5.25 V. It features integrated regulators providing 1.25 V, 1.3 V, and 2.7 V outputs with specific source and sink current capabilities. The component is housed in a 48-pin LQFP package and functions reliably across an operating temperature range of 0°C to 70°C.

Feature Summary

• Automatically senses the bus state and transitions between single-ended and low-voltage differential termination modes without external control logic.
• Provides differential failsafe biasing to maintain signal integrity during mode transitions or when no devices are connected.
• Integrates thermal packaging with heatsink ground pins to minimize junction temperature and improve mean time between failures.
• Detects high-voltage differential (HVD) devices and automatically enters a high-impedance disconnect state to prevent bus conflicts.

Applications

• Termination for SCSI-1, SCSI-2, and SCSI-3 parallel interface buses
• Ultra (Fast-20), Ultra2 (SPI-2 LVD), Ultra3, Ultra160 (SPI-3), and Ultra320 (SPI-4) systems
• Multimode active terminators requiring automatic SE/LVD switching

Procurement Notes

Verify that the ordered part number matches the exact suffix FQP, which denotes the 48-pin LQFP package variant. Confirm the operating temperature range requirement aligns with the specified 0°C to 70°C limit. Ensure the design accommodates the necessary bypass capacitors for the TRMPWR, REG, and DIFFB pins as detailed in the application information section of the datasheet.

Selection Notes

Select this component for applications requiring a monolithic solution for both SE and LVD SCSI termination. It is suitable for designs needing automatic bus detection to simplify board layout and reduce component count. Verify that the system power supply remains within the 2.7 V to 5.25 V range to ensure proper regulator operation and termination accuracy.

Part Context

This device belongs to the Unitrode family of SCSI terminators, specifically engineered to support the evolution from single-ended to low-voltage differential signaling. It addresses the need for backward compatibility in mixed-mode SCSI environments while maintaining signal integrity for high-speed data transfers up to Ultra320 speeds.

Replacement Considerations

UCC5628FQPG4 is a lead-free and RoHS-compliant version of the same device offering identical electrical characteristics and pinout compatibility.

FAQ

How does the UCC5628FQP detect the bus mode?

It monitors the DIFFSENS line voltage. A voltage below 0.5 V indicates single-ended mode, between 0.7 V and 1.9 V indicates LVD mode, and above 2.4 V indicates HVD mode, causing the device to enter a high-impedance state.

What is the function of the DISCNCT pin?

The DISCNCT pin shuts down the terminator when it is not located at the end of the bus. Pulling this pin low enables the terminator functionality.

Can this device be used on a High Voltage Differential (HVD) bus?

No. If an HVD device is detected, the UCC5628FQP switches to a high-impedance state and cannot terminate an HVD bus.