SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
The EVENT_UP_SEL enables 4 different modes of DPWM Event Updating. The DPWM needs a period of 72 nanoseconds (nominal) to update its timing for the next period. During this period, it takes the latest Filter outputs and any firmware changes to register values and recalculates the timing of the DPWM signals. The time selected for update should NOT have any DPWM edges moving in or out of the window.
If DPWM edges move in or out of the Event Update Window, those transitions may be missed, leading to DPWM pulses longer or shorter than expected.
The modes are:
Note that all modes except for mode 1 make the Event Update timing dependent on the position of the sample trigger. For most topologies, mode 1 is used, and dead times or minimum pulse widths are used to keep moving edges out of the first 72nsec of the DPWM period. Please refer to the reference firmware code provided with UCD3138 EVMs for specific guidance regarding each topology.