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National analog equalizer affords high ESD protection

Posted: 08 Dec 2004 ?? ?Print Version ?Bookmark and Share

Keywords:national semiconductor? national? analog equalizer? storage area network? san?

National Semiconductor Corp. introduced a multi-gigabit analog equalizer that extends the reach of high-speed switch, router, storage area network (SAN) and server backplanes. "Without the equalizer, the I/O can drive 12 to 20 inches. With the equalizer, however, the I/O can drive 40 to 60 inches. That is extending the reach of the signal over the PCB," said Vasanta Madduri, product marketing manager for National Semiconductor's Communications Interface group.

The EQ50F100 offers best-in-class signal integrity and 8kV of electrostatic discharge (ESD), providing manufacturers with the greatest backplane protection in the industry, according to the company.

High-speed I/Os need ESD protection to meet the high performance and reliability requirements of telecom, datacom and storage systems. "During normal maintenance servicing of these systems, the line cards interfacing to PCBs or cable I/O connector pins are susceptible to damaging ESD pulses. These applications require robust ESD structures to prevent such damage," Madduri said.

ASICs and FPGAs are designed with smaller geometries (0.13nm to 90nm) to enable higher densities and lower power, but these smaller geometries also cause higher ESD susceptibility and these products mostly provide only 1kV to 2kV of ESD protection. Discrete signal conditioning devices like the EQ50F100 can be easily designed to provide up to 8kV of ESD protection. The EQ50F100 buffers the incoming signals and protects the more expensive ASICs and FPGAs from ESD, Madduri said.

This device was jointly developed with analog signal processing developer Quellan Inc.

The EQ50F100 backplane equalizer compensates transmission medium losses and reduces the medium-induced deterministic jitter in printed circuit backplanes, resulting in data rates up to 6.25Gbps. The EQ50F100 meets data rates for 10Gb attachment unit interface (XAUI), fiber channel and advanced telecom computing architecture (ATCA) backplanes.

"The small package size, very high ESD protection and signal driving capabilities of the EQ50F100 make it an ideal complement to any board driving a high-speed signal over a backplane," said Jeff Waters, product line director for National Semiconductor's Communications Interface group. "Our EQ50F100 will allow communications, SAN and telecommunications equipment makers to meet their high-density, low-power requirements without replacing their existing line cards."

The EQ50F100, comprised of an equalizer, limiting amplifier and output driver, reduces system cost and power consumption by packing more high-speed backplane channels into less space. The EQ50F100 is coding-independent, operates equally well on 8B/10B or scrambled bit signal streams, and features on-chip current mode logic (CML) terminations on data inputs and outputs. Its 3-by-3mm packaging allows easy placement and routing.

The EQ50F100 can be paired with National's SCAN50C400 high-speed quad multi-gigabit serializer/deserializer (SerDes) transceiver introduced earlier this year to extend signal reach and enable the SCAN50C400 to transmit 5Gbps signals across legacy backplanes that were originally designed for lower data transfer rates (1.25Gbps).

The higher rate of data transmission removes the need for "fork-lift upgrades" in existing backplanes, Madduri said. "With a simple switch card upgrade, the system vendor can reuse the existing chassis, line cards providing a migration path to higher bandwidth line cards with more services and lower cost. The other option is to completely redesign the chassis (a forklift upgrade), which is expensive," she said.

The EQ50F100 and SCAN50C400 also can interface easily with an ASIC, FPGA, or other discrete SerDes that operates from 1.25Gbps to 6.125Gbps, providing customers with higher signal integrity, better ESD protection and greater design flexibility.

"As backplanes are designed to handle XAUI and higher data rates, a higher level of robust operation is demanded between the passive components of the channel and the electrical I/O driving it," said John D'Ambrosia, manager for semiconductor relations at Tyco Electronics. "National Semiconductor and Tyco Electronics have demonstrated error-free operation with the SCAN50C400 SerDes and EQ50F100 equalizer over different Tyco Z-PACK HM-Zd platforms based on low-cost FR-4 substrate."

Packaged in a 6-pin LLP package, the EQ50F100 is priced at $4.95 in 1,000-unit quantities. National's high-speed SerDes (SCAN50C400) sells for $99 each in 1,000-piece quantities.

- Bettyann Liotta

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