SPRUHX5I August 2014 – May 2024 TMS320F28374S , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376S , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378S , TMS320F28379S
The CMPSS has two sources of offset errors: comparator offset error and compdac offset error. In the data sheet, the comparator offset error is referred to as Input referred offset error and compdac offset error is referred to as Static offset error. See the device data sheet for the values.
If both inputs of the comparator are driven from a pin, only the comparator offset error applies. However if the inverting input of the comparator is driven from the compdac, then only the compdac offset error applies. This is because the compdac offset error includes comparator offset error.
Due to the offset errors, the CMPSS must be calibrated to make sure trips happen at the expected levels. The following flow outlines how the calibration can be performed if the inverting input of the comparator is driven from the compdac.
Notes before calibration:
This approach sweeps down the compdac:
It is also possible to calibrate the CMPSS, if both inputs of the comparator are driven from a pin. For this case, the flow stays the same but the voltage on the inverting pin of the comparator is swept externally.