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Dual-input clock generator maximizes network uptime, system stability

Posted: 04 Apr 2007 ?? ?Print Version ?Bookmark and Share

Keywords:dual-input clock generator? network clock generator? clock generator IC?

AD9549 dual-input clock generator from ADI

Analog Devices Inc. (ADI) has unveiled the AD9549 dual-input network clock generator that promises a new performance standard to maximize network uptime and increase system stability and reliability.

DDS technology
Using a new architecture based on the company's direct digital synthesis (DDS) technology, the AD9549 enables a stable holdover, allowing additional time for designers to restore the clock reference in the event of a failure. If an input reference clock fails, the clock generator IC continues to "hold" the output frequency until the reference failure is recovered. With the AD9549, there is no time limit to holdover, which means the output will be maintained until the system is powered down or a new reference is provided. Compared to other solutions, this holdover functionality claims to improve stability by as much as two orders of magnitude, resulting in increased system uptime.

The AD9549 features A and B reference inputs with switchover. This feature enables a system output clock to maintain operation in the event the primary reference clock fails. The device also enables users to set loop bandwidth to optimize reference-A-to-reference-B switching time.

600fs jitter
This dual-input network clock generator reduces jitter to 600fs. The device has a programmable digital loop filter capable of bandwidths down to below 1Hz. Its integration with DDS technology enables such narrow loop filter bandwidths and switchover with extended holdover capability functions. For example, these narrow bandwidths enable the device to clean jitter from noisy input clocks, maximizing data converter performance.

Additionally, the AD9549 provides flexible output frequency options, enabling system designers for non-networking applications to avoid additional frequency translation circuitry.

When combined with AD951x family of clock distribution ICs and high-speed AD9445/6/7 ADCs, the AD9549 can be used to create a complete clock path.

The AD9549 will be available in full production quantities June 2007. The device is priced at $10.95 per unit in 10,000-unit quantities and is available in a 64-lead LFCSP package.

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