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Clock synthesizers cut costs

Posted: 20 Oct 2005 ?? ?Print Version ?Bookmark and Share

Keywords:micrel? system-on-chip synthesizer? sy89537l? sy89538l?

Micrel Inc. rolled out two precision, low-jitter clock system-on-chip synthesizers that are said to provide an extremely high level of integration for system timing generation.

The SY89537L and SY89538L include a phase-locked loop (PLL) that accepts a crystal or reference input, multiple clock dividers and four low-voltage pseudo emitter-coupled logic (LVPECL) outputs and one low-voltage differential signaling (LVDS) output bank of three that are all externally programmed for output frequencies between 29MHz and 756MHz.

The clock synthesizers provide a new level of integration for large, differential LVPECL and LVDS clock generation and distribution applications, said Thomas Wong, VP of Micrel's high bandwidth product group. "Using these solutions, networking timing and routing engine cards will see a tremendous cost savings as well as a significant savings in board space and design time when compared to the discrete logic alternatives currently on the market."

The SY89537L and SY89538L both feature a PLL front end that synthesizes a clock from a crystal or clock reference input. Output frequency is programmed between 29MHz and 756MHz with a 6-bit parallel control bus. In addition, each LVPECL output and LVDS output bank can switch between two clock frequencies, making it a suitable clock source for interface cards that require legacy compatibility or interface card timing options, according to Wong.

The SY89537L and SY89538L are both 3.3V 10 percent compatible, and are guaranteed over the full industrial temperature range (-40C to 85C). Total generated jitter (TJ) performance is guaranteed to be less than 100-ps peak to peak. In addition, the unique input isolation on the input multiplexers minimizes the crosstalk-induced jitter contribution to less than 0.7ps rms.

The SY89537L is offered in a 7-by-7mm, 44-pin MLF package (QFN Jedec standard) and the SY89538L is offered in a 10-by-10mm, 64-pin TQFP. Both devices are already available. Pricing starts at $9.94 in 1,000-unit quantities.

- Bettyann Liotta


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