SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
As seen in Figure 7-146 two sets of DACVAL registers, DACVALA and DACVALS, are present in the buffered DAC module. DACVALA is a read-only register that actively controls the buffered DAC value. DACVALS is a writable shadow register that loads into DACVALA either immediately or synchronized with the next EPWMSYNCPER event. DACVALA update source is selected by the CONTROLSS_DAC0_DACCTL register LOADMODE bit. The power-on default of LOADMODE = 0, which selects the immediate update mode.
The internal DAC reference voltage source, DACREF, is selectable between DACVREF and VDDA18_LDO. The CONTROLSS_DAC0 register DACREFSEL bit selects between these two VREF sources. The DACVREF source routes to the DACVREF pins of the device. The VDDA18_LDO source selects an internal route to the on-die 1.8V analog LDO output. In all normal applications the DACVREF pins should be used as the VREF source. The VDDA18_LDO VREF source option is present only for diagnostic or debug purposes. The power-on default of DACREFSEL = 0, which selects the DACVREF source pins.
Before the selected DACVALA register value is applied to the DAC, an additional calibration offset value is applied. During production DACOUT is calibrated to a nominal 1.8V VREF source offset with the calibration offset stored in e-fuse for use by the buffered DAC. The power-on default options select this pre-calibrated offset value.
Assuming this pre-calibrated, default offset value is used, the output voltage DACOUT (in volts) is calculated with the following equation:
See the below Section 7.4.4.2.2 for more information on the DAC offset adjustment.