First 9-Bit Transceiver Achieves Speeds of Fast-20 SCSI

DALLAS (September 13, 1995) -- The industry's first nine-channel differential transceiver for the Small Computer System Interface (SCSI) I/O bus achieving the speeds of Fast-20 SCSI, or 20 million data transfers per second, is now available from Texas Instruments.

This device, the SN75976A, is ideally suited for applications such as hard disk drives and host adapter add-in boards which interface a computer system to a differential SCSI I/O subsystem. Increased data switching performance, compact packaging and very high protection from electro-static discharge make the SN75976A appropriate to use in today's smallest peripheral devices.

Fast-20 SCSI, formerly known as Ultra-SCSI, has been defined by the ANSI X3T10 Committee in document X3T10/1070D, which recently passed its public review period without comment. Fast-20 SCSI doubles the synchronous transfer rate from the current SCSI-2 standard of 10 million transfers per second, while maintaining compatibility with older synchronous and asynchronous protocols.

The throughput of a computer's I/O subsystem has become increasingly critical with the advent of multi-user systems and applications that require frequent transfers of large amounts of data. Doubling the speed of the SCSI bus to 20 million transfers per second with Fast-20 SCSI prevents the I/O bus from becoming a performance bottleneck in today's high-performance computer systems.

Key Features/Benefits

• Fast-20 SCSI speeds
  Capable of performing 20 million data transfers per second over a SCSI I/O bus. Also compatible with the Intelligent Peripheral Interface (IPI) specification.
• Small SSOP and TSSOP packages
  Saves space on the smallest host bus adapters or devices.
• ESD protection six times greater than industry standard
  Increased ESD and noise protection on the RS-485 I/O terminals that can be coupled to external cables (12kV per human-body model and 600 V per machine model).
• Differential signals
  Reduced channel cross-talk and improved signal-to-noise ratio. Increased cable lengths from 1.5m (single-ended) to 25m.

End Equipment Applications

The SN75976A can be used in host bus adapter add-in boards for computer systems or peripheral devices such as hard disk or tape drives. Differential SCSI (and the SN75976A) are typically used in multi-user computing environments such as;

• Video servers
• Network servers
• Minicomputers
• Mainframe computers
• RAID's (redundant array of inexpensive disks)

Pricing, Packaging and Availability

The SN75976A comes in two packages and two speed grades. The speed grades can achieve Fast-SCSI's 10 million transfers/sec. or FAST-20's 20 million transfers/sec. Packages include a 56-pin shrink small outline package (SSOP) with 25 mil terminal pitch and a 56-pin thin shrink small outline package (TSSOP) with 20 mil terminal pitch.

The SN75976A is available now from TI and its authorized distributors. Suggested resale pricing in quantities of 1,000 in SSOP packaging begins at $10.60 for Fast-10 speeds and $14.44 for the Fast-20 version. In a TSSOP package, pricing is $11.55 and $15.44 for the Fast-10 and Fast-20 versions respectively.

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