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
Each reference 12-bit DAC can be configured to drive a reference voltage into the negative input of the respective comparator. The reference 12-bit DAC output is internal only and cannot be observed externally.
Two sets of DACxVAL registers, DACxVALA and DACxVALS, are present for each reference 12-bit DAC. DACxVALA is a read-only register that actively controls the reference 12-bit DAC value. DACxVALS is a writable shadow register that loads into DACxVALA either immediately or synchronized with the next EPWMSYNCPER event. The high and low reference 12-bit DAC (DACx) can optionally source the register DACxVALA value from the ramp generator instead of the register DACxVALS.
The operating range of the reference 12-bit DAC is bounded by DACREF and VSSA. The high-voltage reference is VDDA by default, but the high voltage reference can be configured to be VDAC using the COMPDACCTL register. The reference 12-bit DAC is illustrated in Figure 16-3.
The output of the reference 12-bit DAC can be calculated as:
Users must design the system carefully so that if the input signal crosses either DACH or DACL and trips the associated comparator, the input signal stays more than a “CMPSS DAC output disturbance” away from the other comparator trip point for “CMPSS DAC disturbance time”.