In document SPNU499B, revised August 2013, the ECLK module supports output frequencies lower than 20MHz. This applies to the TMS570LS3137.
Looking at SPNU489C (which applies to the TMS570LS20206) the ECLK module used to support up to 80MHz.
As the TMS570LS20206 is not recommended for new designs and the recommendation is to use a TMS570LS21x or TMS570LS31x instead I was wondering why the maximum frequency of the ECLK was limited on the newer version of the device. Is this a limitation that always existed but was only documented on the 3137 ?
I have a design that currently outputs 50MHz (although the datasheet specifies a maximum of 20MHz) on the TMS570LS3137, I have measured the clock and it is appropriate for our use at room temperature. The levels are from 0 to around 3.2/3.3V and the rise/fall times are acceptable.
I would also be interested to understand if the ECLK frequency is likely to degrade at temperature extremes as I can not easily measure 50MHz when the hardware is in the oven.
Is there any safety implication in outputting a frequency above 20MHz on the ECLK module or is it simply the output buffer that will limit rising/falling times, high/low voltages ?
Any help in answering those questions is greatly appreciated.
