The Power Management Bus (PMBus) is an open-standard, two-wire digital communication protocol designed specifically for configuring, monitoring, and controlling power conversion devices. It is built on top of the physical layer of the System Management Bus (SMBus), which itself is a derivative of the I2C protocol. PMBus defines a standardized command language for power supply-related tasks. This allows for interoperability between PMBus-compliant devices from different manufacturers.
A system's host controller (like a main processor or microcontroller) can use the PMBus to communicate with and manage multiple power converters, power supplies, or battery systems within a single piece of equipment. Using PMBus, the controller can precisely configure output voltages and currents, set protection limits (like over-voltage and over-current trip points), and monitor a wide range of parameters in real-time. This includes reading back the actual output voltage and current, measuring the device's internal temperature, and checking its status for faults or warnings.
This level of digital control and monitoring enables more intelligent and efficient power management, improves system reliability by allowing for early fault detection, and can provide valuable telemetry data for performance analysis. It is commonly found in complex systems with multiple power rails, such as servers, networking equipment, and high-end industrial systems.