Linear Technology has introduced a family of silicon oscillators, LTC6905-xxx, that generate a fixed frequency clock output from 20 MHz to 133 MHz and can operate over the full automotive temperature range (-40° C to 125° C). Available in a 3x3 mm ThinSOT package and requiring no external trim components, the oscillators operate with a single 2.7 V to 5.5 V power supply and provide a rail-to-rail CMOS output. Applications include timing solutions for FPGAs, CPLDs microprocessors and DSPs.
Silicon oscillators offer significant advantages over traditional resonating elements, according to Doug LaPorte, design section lead at Linear Technology. “Silicon fabrication and assembly ensures that these devices are inherently immune to shock and vibration,” he said. “Typical canned oscillators are challenged by long startup, duty cycle drift, and significant power usage. The LTC6905-xxx improves on all of these features with a consistent startup (100 us typical), low duty cycle variation (+/-2.5%) and half of the power consumption (12 mA max at 100 MHz).
The LTC6905-xxx family is available with a master clock frequency of 133 MHz, 100 MHz, 90 MHz, or 80 MHz. An internal three-state divider (DIV input) allows for division of the master clock by 1, 2 or 4 providing a wide range of possible frequencies. For non-standard frequencies, the LTC6905-xxx can be factory trimmed to any output between 2.2 MHz and 170 MHz. A resistor programmable version is also available for applications requiring factory or field adjustment to any frequency from 17 MHz to 170 MHz.
