What is down spread modulation and when is it used?
When a system can not tolerate an operating frequency higher than the nominal frequency (often called over-clocking), then a down spread option should be considered. In Figure 8 above, the down spread diagram provides an example of a device with a +/-2.0% down spread percentage. For this example, if a customer was concerned about over-clocking and had a maximum operating frequency requirement of 100MHz (FO), typical frequencies for FMIN and FMAX would be 98MHz and 100MHz, respectively. For a down spread device, the maximum instantaneous output frequency (FMAX) is limited to the nominal frequency (FO).
