0 Replies Latest reply on Jun 30, 2012 7:57 AM by content.librarian

    CY2305 Output Reaction when Input is stopped!

      This is not recommended way of operation and is not intended either. However, if someone wants to know if the input reference clock is suddenly stopped (0MHz), how many cycles of CLKOUT will keep as the former output clock, then the output changes to unlock, it was measured to see how the CY2305 behaves under nominal conditions (25C and 3.3V).

      The output usually holds the original frequency for only a few cycles. Generally you cannot expect more than 2 or 3 cycles at the normal frequency. It then drops towards a lower frequency. For example,

      100 MHz drops towards 80 MHz, stops after ~120 cycles
      80 MHz drops towards 70 MHz, stops after ~120 cycles
      60 MHz drops towards 50 MHz, stops after ~90 cycles
      40 MHz drops towards 30 MHz, stops after ~50 cycles
      20 MHz drops towards 14 MHz, stops after ~25 cycles
      10 MHz goes very quickly towards 5 MHz, stops after ~10 cycles

      In all cases, the output clock stops in about 1.5 to 2 microseconds.