EE Product News

Frequency Of New Spread Spectrum Clock Tops Out At 165 MHz

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With a maximum clock frequency of 165 MHz, the SM561 is reported to be the highest frequency spread spectrum clock generator chip available today. The record speed combined with a number of other technical advances are designed to help the new clock chip boost the performance of PCs, notebooks, PDAs, LCD monitors, printers, copiers, modems, routers, and other electronic products. It is said to even qualify for use in driving Ultra Extended Graphics Array (UXGA) devices.
Among the other features touted for the SM561 clock generator is a 3-state programmable logic control that allows two pins to be used to select from nine different percentages for spread spectrum clock variation. Spanning a selection range of from 1% to 3.5%, the automatic clock variation spreads clock energy emissions over side bands and reduces EMI up to 6 dB. In addition, at the higher frequencies the percentage of spread is self-adjusting, further reducing cycle-to-cycle and long-term jitter. This programmable approach to reducing EMI is said to represent a considerably less expensive way of meeting FCC EMI specs than by use of filtering and metal shielding.
The clock generator chip can accept inputs from crystals or another clock generator, with the SM561 offering a 60 to 165 MHz operating range and the SM560 a 25 to 120 MHz range. In quantities of 1,000, the 8-pin SOICs cost $2.15 and $1.95 each, respectively.

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