1 Introduction

At a high level, digital current sense monitors (also called digital power monitors) consist of an analog front end that is designed to take differential measurements across a sense resistor at a high common mode voltage, an internal analog to digital converter, and a digital output to provide the measurement data to the rest of the system. I²C digital current sense monitors, such as the INA233 (Figure 1-1), offer one shot measurement capabilities which allow the I²C controller (main) to tell the current sense monitor (secondary) to initiate a single measurement. Since traditional I²C communication exists between one main and one addressable secondary on the I²C bus, it is not possible for a single main to initiate a synchronized one shot measurement for multiple secondary devices. However there could be exceptions where commands are provided specifically for this function.

The Power Management Bus (PMBus) is a variation of the System Management Bus (SMBus) which was created for controlling power devices with digital interfaces. Both PMBus and SMBus are based on two-wire open-drain electrical signaling like I²C , but have additional application- specific features. In the case of desiring synchronized measurements between or across multiple digital current sense monitors, a group command exists within PMBus that allows the main to address multiple secondaries sequentially, but execute the command at the same point in time.