Simpler design of multiple line rate cards

12th August 2013

Nat Bowers

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Datasheet

Semtech has today introduced a new low phase noise clock synthesizer, the ACS1790T. Featuring typical RMS jitter below 500 femtoseconds, the ACS1790T is a tiny device offering frequency selection better than one part-per-billion on a low phase noise platform. The ACS1790T is suitable for a wide range of demanding applications including 10G Ethernet, Synchronous Ethernet, SONET/SDH, FibreChannel, CDR, software controlled clock generation and other reference clocks.

“The ACS1790T represents a key milestone in our mission to provide our customers complete timing solutions. It is our first really low phase noise product and is a great leap forward in performance, perfectly complementing our ToPSync product line and also serving as a versatile stand-alone frequency synthesizer with outstanding performance,” comments David Spencer, Marketing Manager for the Semtech Timing Products.

The ACS1790T can be used as a stand-alone frequency synthesizer or as a companion chip to the ACS9522T ToPSync system synchronization solution, generating a low phase noise local reference clock that is aligned to the system timing recovered by the ACS9522T.

The ACS1790T offers outstanding flexibility with a 24-bit fractional feedback divider as a standalone frequency synthesizer. This generates any output frequency with a resolution of 0.5 parts-per-billion, allowing synthesis of any output frequency within the range of 10 MHz to 200 MHz on the LVPECL output and 2 KHz to 125 MHz on the LVCMOS output.

Packaged in a 4mm x 4mm 24-QFN package, the ACS1790T features a total solution footprint ideal for space-constrained applications. All loop components are on-chip, simplifying the circuit board layout. The combination of a high fractional resolution with a simple serial interface makes the ACS1790T an ideal solution for use in software-controlled loops requiring a translated but disciplined or traceable clock.

ACS1790T key features:

Very low RMS phase jitter, < 500 fs typical (integrated from 12kHz-20MHz),
Flexibly generates any frequency within following frequency ranges with 0.5 ppb precision:

- LVPECL output: 10 MHz - 200 MHz,

- LVCMOS output: 2 KHz – 125 MHz.

Supports 1G/10G Ethernet, SONET/SDH, E1/T1, PCI Express and many other standards,
Pin-strapped start-up modes for 1G / 10G Ethernet frequencies,
Simple serial interface for control and configuration,
4mm x 4mm 24-QFN package.

Pricing and availability:

The ACS1790T (order code: ACS1790IMLTRT) is available now in production quantities and is priced at $9.00 each in 10,000-piece lots. Semtech offers comprehensive design assistance, including field- and factory-based support.