Strengths, faults of LVDS fail-safe circuits

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In recent years, LVDS for high-speed data interconnections has found many applications in consumer electronics, high-speed computer peripherals, telecoms/networking and wireless base stations. LVDS has distinctive performance, power, noise, EMI-reduction and cost advantages. With the right settings at a data rate of 100-800Mbps, the LVDS signal can reach as far as 10-15m in a twisted-pair cable link or >1m in a PCB trace pair. The power dissipated by the 100 load is a mere 1.2mW relatively independent of frequency.

In this article, Senior Engineer Chung Wu of Maxim Integrated Products Inc. discusses the design, operation, strengths and shortcomings of three different fail-safe circuits: external-biasing, in-path and parallel circuits. There is no single all-perfect solution for an LVDS fail-safe function. The analysis shows, however, that the parallel method can work well in more situations than either of the other two methods.

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