Part Number: TMS570LC4357
Tool/software:
Dear Ti,
In the datasheet for the TMS570LC4357, the mibADC section lists the following regarding the ADC counts in 12-bit mode:
1 LSB = (AD_REFHI – AD_REFLO) / 2^12
Using this formula, the corresponding voltage should be
AD_REFLO + (ADC_COUNT) * (AD_REFHI – AD_REFLO) / 2^12
This formula does not seem correct to me. Suppose the ADC is reporting the max value for a given pin, 0xFFF. Intuitively, we would expect our voltage to be AD_REFHI (or greater). However, since 0xFFF equals 2^12 - 1,
we instead get a voltage that is less than AD_REFHI. In fact, our ADC is never able to detect voltages equal to AD_REFHI using this formula.
Should the formula instead be
1 LSB = (AD_REFHI – AD_REFLO) / (2^12 - 1)
or is the former formula correct?
