As explained by the Power Management Bus Implementer's Forum, “The Power Management Bus (PMBus) is an open standard power-management protocol with a fully defined command language that facilitates communication with power converters and other devices in a power system. The protocol is implemented over the industry-standard SMBus serial interface (a version of I2C) and enables programming, control, and real-time monitoring of compliant power conversion products. This flexible and highly versatile standard allows for communication between devices based on both analog and digital technologies, and provides true interoperability which will reduce design complexity and shorten time to market for power system designers. Pioneered by leading power supply and semiconductor companies, this open power system standard is maintained and promoted by the PMBus Implementers Forum (PMBus-IF), comprising 30+ adopters with the objective to provide support to, and facilitate adoption among, users.”
Using PMBus commands, a designer can set a power supply's operating parameters, monitor its operation and perform corrective measures in response to faults or operational warnings. The ability to set a power supply's output voltage allows the same hardware to provide different output voltages by merely re-programming. The ability to monitor and maintain a PMBus system enhances its reliability and availability.
As it stands today, all users of PMBus for dc-dc converters must obtain a license from Power-One (Camarillo, CA), holders of the patents for digital control of dc-dc converters.
Linear Technology has licensed Power One's Digital Power Technology so users of Linear's digital system management products do not require it.