PMBus: Digital Power Control Protocol

DATA COMMAND FORMATS FOR OUTPUT VOLTAGE AND RELATED PARAMETERS
Data for commanding or reading the output voltage or related parameters can be in one of three different formats depending on the type of device:

• Linear scale commanded and reported using a two-byte unsigned binary integer with a scaling factor (similar in concept to a mantissa and exponent).
• VID code format of popular microprocessors.
• Direct format that uses an equation and device-supplied coefficients.

Power supplies and power converters generally have no way of knowing whether their outputs are connected to ground. However, power supplies treat most output voltages as " positive." Therefore, all output voltages and output voltage-related parameters of PMBus devices are commanded and reported as positive values.