Hello All.

We are using STM32f469 in our project. When we use internal clock (16MHz ) for getting ADC clock , the number of ADC samples we are getting - 664
When we use external clock (16MHz) for getting ADC clock , the number of ADC samples are 1100.

Why is the variation in samples for same clock speed?

 

Check the datasheet for clock prescalars and the registers that control them. Phase locked loops, PLLs, allow for easy adjustment of clock frequencies inside of the processors.