UCC5638FQPTR

Overview

The UCC5638FQPTR is a multimode SCSI active terminator designed for seamless integration into Low Voltage Differential (LVD) and Single Ended (SE) SCSI Parallel Interface architectures. It automatically detects the bus type via the DIFFSEN signal and switches termination modes accordingly. The device supports SPI-2, SPI-3, and SPI-4 standards, operating within a 2.7V to 5.25V supply range. It features integrated regulators for differential and single-ended biasing, providing fail-safe biasing to ensure signal integrity. Packaged in a 48-pin LQFP with thermal grounding, it operates from 0°C to +70°C.

Feature Summary

• Automatically senses the SCSI bus state and switches between single-ended and low voltage differential termination modes without external control logic.
• Integrates dedicated voltage regulators and impedance trimming circuits to maintain precise termination characteristics across varying supply voltages.
• Includes high-impedance shutdown capability when High Voltage Differential (HVD) devices are detected on the bus to prevent electrical conflicts.

Applications

• Termination for Ultra2 (SPI-2) LVD SCSI buses
• Termination for Ultra3 and Ultra160 (SPI-3) SCSI systems
• Termination for Ultra320 (SPI-4) SCSI architectures

Procurement Notes

Verify that the specific ordering suffix matches the required packaging configuration. Confirm the temperature grade aligns with the intended operational environment. Ensure the component status is listed as active production before finalizing procurement plans. Cross-reference the datasheet revision date to guarantee compatibility with current design specifications.

Selection Notes

Select this component for applications requiring automatic mode switching between SE and LVD SCSI terminations. Ensure the system power supply remains within the 2.7V to 5.25V operating range. Verify that the PCB layout accommodates the 48-pin LQFP package dimensions and provides adequate thermal relief for the ground pins to manage junction temperatures effectively.

Part Context

This part belongs to the UCC5638 family of multimode SCSI terminators manufactured by Texas Instruments. It serves as a bridge technology allowing legacy single-ended SCSI devices to coexist with newer low-voltage differential implementations. The FQP designation indicates the specific quad flatpack package variant used for surface mount assembly.

Replacement Considerations

The UCC5638FQPTR.A is an equivalent alternative within the same product family offering identical functionality and pinout compatibility. Both variants share the same active production status and packaging specifications.

FAQ

How does the UCC5638 detect the SCSI bus type?

It monitors the DIFFSEN line voltage levels. A voltage below 0.5V indicates single-ended mode, between 0.7V and 1.9V indicates LVD mode, and above 2.2V triggers a high-impedance shutdown for HVD detection.

What is the purpose of the DISCNCT pin?

The DISCNCT pin shuts down the terminator when the device is not located at the end of the SCSI bus, reducing power consumption and preventing improper termination.

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

No. If an HVD device is detected, the UCC5638 automatically switches to a high-impedance state and does not function as a terminator on HVD buses.