Microchip — PAC194x and PAC195x Multi-Channel Current and Power Monitors

The PAC195x family of products from Microchip are 1-, 2-, 3- and 4-channel energy monitoring ICs for measuring the power behavior of complex electronics systems such as servers and laptop computers. They comprise bus-voltage monitors and current-sense amplifiers which interface to high-resolution on-chip ADCs.  

The PAC195x ICs’ digital circuitry performs power calculations, and measures an accumulated value for energy consumption based on the results of coulomb counting. It can sustain energy monitoring over integration periods of longer than a year. Bus voltage, sense resistor voltage and accumulated proportional power are stored in registers for retrieval by the system host or embedded controller.  

There are two versions of the PAC195x products: the PAC195x-1 devices are for high-side current sensing, and the PAC195x-2 devices are for low-side current sensing, or for applications that have a floating bus voltage.  

The PAC195x provides an SMBus and I2C interface for controlling the sampling rate up to 1,024 samples/s, as well as the energy integration period. Active channel selection, single-shot measurements and other controls are also configurable via SMBus or I2C. 

The PAC195x power monitors use real-time calibration to minimize offset error. No input filters are required. An external sense resistor is used to set the full-scale current-measurement range. A very low input current simplifies routing.