SLVUAW9C September 2016 – February 2020 UCD90320
Section 6 of the PMBus specification describes the memory model for PMBus devices. Values used by the PMBus device are loaded into volatile Operating Memory from one or more of the following places:
The UCD90320 contains RAM that is used as Operating Memory. Embedded Data Flash memory is used to implement the hard-coded values and the Default Store values. Hard-coded values require a new firmware revision. Values in the Default Store may be changed using the STORE_DEFAULT_ALL command described in Section 6.3.
Section 6.1 of the PMBus specification describes the ordering of memory loading and precedence. In general, the hard-coded parameters are loaded into Operating Memory first. Second, any pin-programmable settings take effect. Third, values from the Default Store are loaded. Later, commands issued from the PMBus take effect. In all cases, an operation on a parameter overwrites any prior value that was already in the Operating Memory.