SPRUI33H November 2015 – June 2024 TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1
The minimum ADC acquisition window for sampling the PGA_OF filtered signal with one ADC varies based on the values of RFILTER and CFILTER. To make sure of good performance, choose a CFILTER capacitor that is large enough to satisfy most of the ADC sample and hold capacitor (Ch) charge requirements by itself. The CFILTER value can be sized based on the acceptable amount of ADC sampling error (LSBErr):
CFILTER = Ch x 4096 / LSBErr
See Chapter 13 to determine the ADC acquisition window, where the ADC source resistance (Rs) is equal to RFILTER.