TMS320F280025C: SYSCLK与CPUCLK

Since the frequency tolerance of the Internal oscillator is 10MHz +/-2% over full operating range and max device clock frequency is 100MHz, we have some risk of exceeding 100MHz if we choose 10x PLL multiplier with this clock source.  Because of this we step back to give 95MHz nominal, and with variation of internal oscillator we will still not violate the 100MHz max. 

CCS flash tool always uses internal oscillator since it is known frequency and eliminates need or risk of customer manually entering the value of their external clock(if they have one).

For external X-tal, with tighter tolerance, this is not a concern so we can set PLL to full 100MHz when that is the clock source.