The specification for the C5509A core voltage running at 200 MHz is 1.55V min, 1.6V nom, 1.65V max. What would happen if the core voltage were to droop to 1.5V? Would the part run slower? Will the PLL fail to lock? Any other possible issues?
Is there a recommended way to set up voltage supervision for the core voltage? The power supply being used (TPS62302) has an output voltage load regulation spec of .002% / mA max as well as a voltage line regulation spec of .2% / V max and an accuracy of 2%. The C5509A appears to draw .6mA / MHz at 200 MHz for a total of 120mA. The "TMS320VC5503/C5506/C5507/C5509A Power Consumption Summary" application report has a link to a power calculator that suggests a total core current of about 237mW (148mA). I wouldn't expect to see peak currents more than maybe 50% higher. That would mean a load current caused output voltage change of 75*.00002 = 1.5mV. The input shouldn't change more than maybe .2V resulting in maybe a 400uV change. The accuracy of the TPS62302 could put it at .98 * 1.6 = 1.568V. Adding everything together the output could droop to about 1.56V. I'm looking at the TPS3808 adjustable voltage monitor and the negative-going input threshold accuracy is 1.5% max. This means if we were to set the threshold for 1.56V it might not trip until 1.54V.
What's the best strategy for making sure the part is operating correctly?
