New Nine-Channel Transceiver First to Support Both Single-Ended and Low Voltage Differential Signaling
DALLAS (March 16, 1998) -- A new nine-channel low voltage differential (LVD) transceiver from Texas Instruments (TI) is the first discrete transceiver in the industry to support both single-ended and LVD signaling. The device allows designers to upgrade their small computer system interface (SCSI) peripheral devices and other products like SCSI host bus adapters to the faster data transfer rates and longer bus segments of LVD SCSI and still maintain compatibility with existing single-ended SCSI buses. SCSI is a high-performance peripheral interface that distributes data independently of the host computer. This interface is used with devices such as hard disk drives, tape drives, CD-ROMs and scanners.
LVD technology supports the Fast-40 SCSI bus. With the faster switching speeds of LVD technology, a computer's SCSI input/output (I/O) subsystem is capable of 40 million data transfers per second over a distance of 12 meters. Single-ended SCSI supports 20 million transfers per second, but only over a distance of 1.5 meters. LVD signaling, or LVDS, has a lower output voltage than the RS-485 signaling used prior to reduce power consumption. LVD technology can also run off of 3.3V power supplies. LVDS is the latest data transmission standard -- following IEEE 1394 and universal serial bus (USB), among others -- enabled by TI's advanced mixed-signal technology.
The new device, designated the SN75LVDM976, supports nine transmission lines so that only three devices are needed for a 27-bit-wide SCSI implementation. The differential signaling of the 'LVDM976 is more reliable than single-ended signaling because it is less susceptible to electrical noise. It also does not interfere with other electronic equipment since it has a low level of electromagnetic radiation. The 'LVDM976 is pin-for-pin-compatible with TI's nine-channel high voltage differential (HVD) transceiver device, the SN75976ADGG, giving designers even more design flexibility.
The SN75LVDM976 is not limited to SCSI applications. It can be used to implement any type of multipoint parallel differential bus including proprietary buses, backplane systems and direct board-to-board connections. For example, many redundant telecommunications switching systems are able to assure system availability by means of a direct parallel bus connection between computer boards.
30 Years of Data Transmission Leadership
By leveraging its 30 years of experience with many data transmission standards, including RS-232, RS-422, RS-485, Fiber Channel, universal serial bus (USB), 1394 FireWire™ and others, TI's Mixed-Signal Product group has quickly established a leadership position with its LVDS technology.
The 'LVDM976 joins TI's growing family of LVDS devices, which already includes two four-channel drivers and receivers. In addition, during the first half of 1998 two more four-channel LVDS drivers and receivers, the SN65LVDS3486 and SN65LVDS3487, are scheduled to be available. The 'LVDS3486 (receiver) and 'LVDS3487 (driver) will feature an enabling scheme whereby only two of the four drivers or receivers can be enabled at a time instead of requiring that all four lines are enabled simultaneously. TI also plans to introduce a dual receiver and a dual driver, the SN65LVDS9637 and the SN65LVDS9638 respectively, in the first half of 1998. Both devices follow the footprint of previous dual receivers and drivers in TI's RS-422 product family.
Pricing and Availability
The SN75LVDM976 device comes in a 56-pin thin shrink small outline package (TSSOP). The SN75LVDM976DGG is available now from TI and its authorized distributors. Suggested resale pricing in quantities of 1,000 is $8.68.
More information regarding TI's mixed-signal product is available on the World Wide Web at 
http://www.ti.com/sc/docs/msp/datatran/default.htm.
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