USB-C PD
Power Negotiation
The PD negotiation will occur with the rule that the sink will look for the source PDO which matches the voltage as per its own capabilities, starting from the highest PDO. The Request Message returns one and only one Sink Request Data Object to identify the PDO (Power Data Object) being requested.
More common is for the PD source to be unaware of the capabilities of the sink. The source advertises the
capabilities and, if a match occurs, the sink returns a request-data object (RDO)
This is similar to that used for Source Port capabilities with equivalent Power Data Objects for Fixed, Variable and Battery Supplies as defined in this section. Power Data Objects are used to convey the Sink Port’s operational power requirements
