New Bus LVDS Family Offers Superior Combination of High Speed (155-400 Mbps), Low Power, Low Cost and Low Noise/EMI

May 25, 1998 -- National Semiconductor Corporation® today announced a family of communication interface ICs that extends the advantages of National's LVDS technology to bus/backplane systems. The Bus LVDS (Bus Low Voltage Differential Signaling) family provides an ideal combination of high speed (155-400 Mbps), low power, and low noise/EMI. The initial family consists of five devices: a low skew 9-channel transceiver, a 10:1 serializer and 1:10 deserializer chip set, a single bus transceiver, and a 1:2 bus repeater.

"As the bandwidth requirements of the information highway explode, clearly the interconnect is still the bottleneck," said Patrick Brockett, vice president and general manager of National's Analog Group. "Bus LVDS is a breakthrough technology that cost effectively solves many of the high bandwidth system issues."

In high bandwidth communications applications such as switched Ethernet, wireless basestations, and telecommunications switching and transmission systems, the new Bus LVDS devices allow designers to achieve major gains in bandwidth without compromising on other features that must be retained to be competitive. For example, Bus LVDS is able to drive a 20-card backplane at 155 Mbps while allowing important bus features such as high impedance on power down and hot insertion capability.

Bus LVDS Breakthroughs
To achieve reliable bus operation, National's Bus LVDS uses a 10 mA loop current (higher than point-to-point LVDS), which ensures enough signal (Vod) in a heavily loaded backplane with double terminations. In addition, its balanced output impedance means that any bus reflections are common mode noise, and therefore do not compromise signal integrity.

A bus or backplane implemented with Bus LVDS devices is simple (only two termination resistors are needed), has high impedance on power down for system fault tolerance, and gives the hot insertion capability needed for system maintenance. These features help decrease system failure issues that commonly occur with today's backplanes.

The combination of features provided by Bus LVDS is truly outstanding, as indicated in the table below:

Parameter	Bus LVDS	TTL/CMOS	GTL/BTL	PECL
Output voltage swing	+/- 300mV	2.4-5.5V	1V	+/- 800mV
Receiver threshold	+/- 100mV	1.2/1.5V	+/- 200mV	+/- 200mV
Max speed(per channel)	>400Mbps	<50Mbps	50Mbps	>400Mbps
Drive	10mA	75mA	40-80mA	40-60ma
Noise	low	high	medium	medium
Hot insertion	yes	no	yes	yes
High Z on power down	yes	no	yes	yes
Implementation	simple	simple	complex	complex

Product innovations
National's Bus LVDS products provide innovative features that improve system performance and cost. For example, the DS92LV1021 and DS92LV1210 serialize and deserialize a 10-bit datapath (and clock) to a high-speed Bus LVDS link. This link is then bussable to multiple deserializers. The serializer/deserializer chipset reduces the amount of bus interconnect by more than an 80 percent, thus reducing overall system cost.

For high-speed parallel multipoint busses, skew across channels and multiple devices is always a concern. The 9-channel transceiver (DS92LV090) features an on-board delay lock that guarantees low chip-to-chip skew -- as low as +/- 200 ps across process, voltage and temperature. This enables multiple datapaths to run at hundreds of Mbps across a multipoint bus.

Pricing and availability
National's Bus LVDS family consists of five devices, with more planned. The DS92LV010 and DS92LV222 are available now in production volumes. The DS92LV090, DS92LV1021 and DS92LV1210 are available for sampling, with production scheduled for Q3, 1998.

Part Number	Description	Speed capability	Package	Price (1ku quantity)
DS92LV010ATM	Single bus transceiver	155 Mbps	8-pin SOIC	$2.50
DS92LV222ATM	1:2 bus "repeater"	200 Mbps	14-pin SOIC	$3.40
DS92LV090TVEH	Low skew 9-channel transceiver	200 Mbps	64-pin TQFP	$8.50
DS92LV1021TMSA	10:1 serializer	400 Mbps	28-pin SSOP	$9.50
DS92LV1210TMSA	1:10 deserializer	400 Mbps	28-pin SSOP	$9.50

For additional product information, visit our World Wide Web site at www.national.com (under Quick Search, type LVDS), or contact National's Customer Response Group at 1-800-272-9959.

National Semiconductor Corporation produces system-on-a-chip silicon solutions for the information highway, based on its leadership in analog and mixed signal technologies. National is headquartered in Santa Clara, California, and focuses on the communications, personal systems and consumer markets. National has annual sales of approximately $2.5 billion and 13,000 employees worldwide. Additional company and product information is available on the World Wide Web at http://www.national.com.

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