0 Replies Latest reply on Jun 20, 2011 4:15 PM by content.librarian

    PPM Stability Spec in Datasheet of CY25701 Explained!


      The ppm values specified in datasheet is ppm with no spread.





      Here is what the data says for each component of PPM in non-spread mode:

      1. Frequency Stability at Room Temp (25C, 3.3V) +/- 25ppm
      2. Frequency Stability Over Temp Range (-20C to 70C, 3.3V) +/- 25ppm
      3. Frequency Stability Over Voltage Range (3.0 to 3.6V) +/- 12ppm
      4. Frequency Stability Over Output Freq Range (10 - 166MHz) Determined from CyberClocks
      5. Aging is +/- 5ppm @25C, First year







      The 4th item is the PPM due to the P & Q that CyberClocks will select for the customer's desired output frequency. This error if any will be a calculated error based upon the one’s exact frequency and application. This will be in addition to the above stated crystal and circuit variations.     



      Since the P and Q values affect the total operation of the internal PLL there is no blanket error budget for the calculated error. One should simply input their frequency into CyberClocks Online and add that error if any to the total PPM budget.







      An example calculation to clear things up is as follows:    



      The CY25701 may be 25 PPM low at room temperature and another 25PPM low at -20C. For this example, the temperature and room tolerance accuracy error would be a total of -50ppm at 3.3 volts and -20C.    



      If you add the stability over voltage and use as an example -12ppm at 3.0V this would set the PPM error at -62ppm low not including aging or the calculated error if any.     



      Next the calculated error for the exact application may be -8ppm.    



      Therefore the total error in this example not counting aging would be -70ppm low at 3.0V,-20C.