Circuit and System Designs of Ultra-Low Power Sensor Nodes With Illustration in a Miniaturized GNSS Logger for Position Tracking: Part II - Data Communication, Energy Harvesting, Power Management, and Digital Circuits
As battery size decreases due to system size constraints in miniature Internet-of-things systems, the internal resistance of the battery increases, resulting in a large IR drop on the battery voltage, complicating battery supervising functions. In this paper, we discuss low-power battery voltage supervisors (BVSs) that are capable of handling this increased IR drop. Battery voltage, battery internal resistance, required threshold voltages, and power-on-reset delay are discussed. As examples, two low-power BVSs fabricated in a 180 nm CMOS process are described.