UCC5630AMWPR/81365

Overview

The UCC5630A is a multimode SCSI terminator designed for LVD and SE bus architectures. It automatically senses the bus via DIFFB to switch between single-ended (SE) and low voltage differential (LVD) termination, entering high impedance for HVD devices. Operating on a 2.7V to 5.25V supply, it supports SPI-2 through SPI-4 standards with integrated fail-safe biasing. The device features a 3pF channel capacitance and includes MSTR/SLV input control. Available in 36-pin SSOP and 48-pin LQFP packages, it operates within a 0°C to 70°C temperature range.

Feature Summary

• Automatically detects and switches between Single Ended (SE) and Low Voltage Differential (LVD) SCSI modes based on bus signals.
• Integrated differential failsafe biasing ensures signal integrity across various operating conditions.
• Supports Master/Slave configuration via the MSTR/SLV pin to manage DIFSENS driver activity among multiple terminators.

Applications

• Termination for Ultra2 (SPI-2), Ultra3 (SPI-3), and Ultra320 (SPI-4) SCSI parallel interfaces.
• Multi-mode active termination environments where SE and LVD devices coexist on the same bus.
• System designs requiring automatic mode selection without manual hardware intervention.

Procurement Notes

Verify the specific package variant required, as the UCC5630A is available in both 36-pin SSOP and 48-pin LQFP configurations. Confirm that the selected part number corresponds to the desired tape and reel quantity or tube packaging. Ensure the component meets the necessary RoHS compliance standards for the target assembly process.

Selection Notes

Select this component for applications requiring seamless transition between SE and LVD SCSI modes. Ensure the design accommodates the 2.7V to 5.25V operating voltage range. Verify that the PCB layout supports the thermal requirements of the HS/GND pins and maintains the strict capacitance balance specified for SPI standards.

Part Context

Originally developed by Unitrode and later acquired by Texas Instruments, the UCC5630A serves as a legacy solution for SCSI bus termination. It addresses the complexity of mixed-mode SCSI systems by integrating multiple termination networks into a single monolithic device, simplifying board design for older computer storage architectures.

Replacement Considerations

UCC5630AFQP

FAQ

How does the UCC5630A determine the termination mode?

It monitors the DIFSENS line voltage. If the voltage is below 0.5V, it selects SE mode; between 0.7V and 1.9V, it selects LVD mode; and above 2.4V, it enters a high impedance state for HVD detection.

What is the function of the MSTR/SLV pin?

The MSTR/SLV pin enables or disables the internal DIFSENS driver. Typically, one master device drives the line while slave devices disable their drivers to prevent contention.

Can the UCC5630A be used on an HVD SCSI bus?

No. If an HVD device is detected, the UCC5630A switches to a high impedance state and disconnects from the bus rather than providing termination.