Gallium Arsenide technology is on its way into high-performance personal computers courtesy of Vitesse Semiconductor Corp, Camarillo, California, albeit only in clock distributors. The VSL4485 and VSL4586 are the first two products in a planned family of multi-feature, low skew clock distribution chips. Designed for use with microprocessors clocked at 50MHz and up, the clock drivers are a direct result of requests from microprocessor manufacturers that identified the need for the function and have worked with Vitesse during the development. The VSL4485 and VSL4586 are designed to simplify distribution and regeneration of TTL clock signals: each features eight outputs with a maximum output-to-output skew of 500pS. The devices also feature optional clock multiplication on two (VSL4485) or six (VSL4586) of the outputs at two or four times the input frequency. Both devices can output tightly controlled clock signals at between 20MHz and 70MHz. Both include a fully integrated phase-lock loop which operates as high as 840MHz and does not require any external analogue components such as capacitors or loop filters. The clock chips can intentionally adjust the outputs in increments as small as 1.25nS for system design flexibility. A test input is provided that enables the phase-locked loop to be bypassed for open-loop operation. The parts are fabricated in Vitesse’s 0.8 micron H-GaAS II process, require a single +5V power supply and are completely compatible with standard TTL input-output levels. The VSL4485 and VSL4586 are being sampled to early customers and general sampling will start next month; for 10,000 units or more, the VSL4485 will be $25, the VSL4586 $27.
