In my application I need to have the option to clock the TMS320C5515 from both CLKIN @ 12MHz & via 32kHz crystal.
In low power mode I'd like to set CLK_SEL =0, CLKIN=0, and use the 32kHz with PLL to achieve 100MHz system clock.
In synchronous mode I'd like to set CLK_SEL=1, CLKIN=12 MHz oscillator.
I'd like to control CLK_SEL via an external uC. The design currently allows the uC to power on/off the TMS320C5515. I also realize that I can't change the mode without a POR.
I have two questions: 1) does this sound feasible? 2) I'd like to still use the PLL when using the 12MHz oscillator. Since 12MHz is much higher that the PLLIN requirements does this mean that I need to divide down the reference clock in oroder to use the internal PLL to go back to 100MHz?
Thoughts would be appreciated.
Victor