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SCSI bus terminators provide flexible solutions

Edited by the Electronicstalk editorial team Jan 6, 2005

A new family of SCSI bus terminators provides flexible solutions for all SCSI bus operational modes from SCSI 1 to SPI 4 (Ultra 320).

A new family of SCSI (small computer systems interface) bus terminators that provides flexible solutions for all SCSI bus operational modes from SCSI 1 to SPI 4 (Ultra 320) has been released by Siliconix.

Built on a high-voltage 0.8-micron BiCMOS process, which enables production of a broad range of competitively priced SCSI products, these new terminator ICs serve as pin- and function-compatible, lead (Pb)-free replacements for the industry-standard UCC56xx series of SCSI terminators.

The new SiP56xx SCSI terminator family from Vishay Siliconix is intended for use in backplanes, host adapters, cabling in RAID disk arrays, storage area networks (SANs), network attached storage (NAS), servers and workstations, industrial computers, and high-end personal computers.

The six new devices are the SiP5630 and SiP5670 nine-line multimode terminators, the SiP5628 and SiP5668 14-line terminators, and the SiP5638 and SiP5678 15-line terminators.

Each of the new multimode terminators' output channels provides termination for one SCSI data signal, parity signal, or control signal.

The termination provides impedance matching of the SCSI bus to minimise signal reflections from the end of the bus, as well as the required SCSI bus biasing for either single-ended (S/E) or low voltage differential (LVD) operation.

Like the popular UCC5630A and UCC5670, the nine-line SiP5630 and SiP5670 feature a 2.7 to 5.25V TERMPWR range for all S/E and LVD specifications.

Both provide a master/slave input and status indicator pins.

They are available in a lead (Pb)-free, thermally enhanced QSOP 36 package.

The new SiP5628 and SiP5668 14-line terminators and SiP5638 and SiP5678 15-line terminators all are available in a thermally enhanced lead-free SQFP-48 package.

The 14-line SiP5628 and SiP5668 terminators serve as an alternative source to the UCC5628, and the 15-line SiP5638 and SiP5678 provide designers with an alternative source to TI's UCC5638.

Both 14-line terminators also feature status indicator pins.

The new multimode SCSI bus terminators sense the operational state of the SCSI bus via the DIFFSENS bus signal and automatically switch to S/E or LVD operation as required, thereby allowing designers to order and implement a single device for newer LVD products and for the older SE devices that remain in use today.

If a high-power differential (HPD) device is used with the SCSI bus, the terminator IC shifts into high impedance mode.

The new terminators also present high impedance to the SCSI bus if the disable pin is asserted or if the TERMPWR supply voltage is removed from the IC.

The SiP5668, SiP5670, and SiP5678 multi-mode terminators all feature an integrated SPI-3 delay filter.

This on-chip mode-change delay enables designers to reduce the size and cost of external passive components for significant board space savings in SPI-3 designs.

To meet the termination resistance requirements of the SCSI standards, Vishay Siliconix uses fusible link technology to trim the termination value.

All six devices are rated for operation over a temperature range of 0 to 70C.

Vishay Siliconix also plans to release a 27-line programmable terminator in a lead-free LQFP 80 package that will serve as an alternative source for the UCC5696.

By providing precise active termination for 27 LVD SCSI bus lines, the device will achieve peak bus performance, permitting the manufacture of more robust and reliable Ultra320 and Ultra640 systems.

This programmable device will be ideal for backplanes that have a lower bus impedance in the 60 to 90ohm range.

Vishay Siliconix is a member of STA, the SCSI Trade Association.

Samples and production quantities of the new 9-, 14-, and 15-line SCSI terminators are available now with lead times of 8 to 12 weeks for larger orders.

Pricing per device for US delivery in 1000-piece quantities is $2.20 for the SiP5628, $1.95 for the SiP5630, $2.30 for the SiP5638, $2.40 for the SiP5668, $2.15 for the SiP5670 and $2.65 for the SiP5678.