HP Announces Schottky-barrier Diodes for Computer Motherboards and Other Digital Applications; Transient Suppression At Picosecond Switching Rates.

PALO ALTO, Calif.--(BUSINESS WIRE)--Sept. 21, 1998-- Hewlett-Packard Company today introduced a series of n-doped silicon Schottky-barrier diodes specifically optimized to maintain signal integrity and to provide circuit protection without compromising space in digital and analog applications.

Using Schottky diodes to conduct signal spikes to ground minimizes the effects of undershoots or overshoots caused by signal reflection and current transients. Circuit burnout, signal distortion and improper system operation are all potential consequences of undershoots and overshoots.

Low series resistance allows the HP HBAT-540x/HSMS-270x diodes to sustain higher current magnitudes without damaging the diodes themselves. With picosecond switching speeds (100 ps carrier lifetime), the diodes can respond to noise spikes with rise times as fast as 1 ns. Low capacitance helps prevent insertion loss and waveform degradation that lead to distorted data.

In contrast to a conventional p-n junction diode, Schottky-barrier diodes carry current only by majority carriers (electrons). Because no minority-carrier (hole), charge storage effects are present, Schottky diodes are faster switching than p-n junction diodes.

Another significant difference between the Schottky-barrier and p-n diode is the forward voltage drop. Schottky diodes have a typical threshold of 0.3V, in comparison to the 0.6V of silicon p-n junction diodes. This provides signal limiting of undesirable spikes and ringing.

An example of where Schottky diodes termination is useful is on high-speed data lines in computer memory buses. Mismatched impedances lead to signal reflection, which can interfere with timing and output quality of the clock signal generator of the entire system. Schottky diodes are a better alternative to resistive, Thevenin-equivalent, matching circuits because some systems have variable or unknown impedances. Schottky diodes have the special advantage of protecting delicate circuitry from data spikes and consuming less power -- crucial in portable applications where battery life is precious.

Two basic diode types are available. The HBAT-5400 version features lower capacitance than the industry's forward voltage and 30V and 15V minimum breakdown voltage (at 100mA)

These diodes are available in the 7.0 square mm SOT-23 surface-mount package, and the even-smar, SOT-23 .17 HBAT-540B single diode, SOT-323 .165 HBAT-540C series pair, SOT-323 .195 HSMS-2700

single diode, SOT-23 .18 HSMS-2702 series pair, SOT-23

.22 HSMS-ponents.

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Information in this release applies specifically to products available ompany, Components Response Center, 3175 Bowers Ave., M/S 88U Santa Clara, Calif. 95054-9929.