Another possible application for digital power monitors is in conjunction with multi-cell balancing ICs to provide additional control and alerts. Battery management systems are used in power tools, battery backup systems, and many portable electronics. Due to the small safe operating window of lithium ion batteries, battery management systems have become an important part of modern electronics. The figure shown here is a simplified circuit for a 6-cell battery pack. The ISL94208 is a multi-cell balancing controller and is ideal for Li-ion batteries. The analog voltage of each cell inside a battery pack is sent to the output via an internal mux, as the ISL94208 does not have an ADC integrated. The voltage on the output is measured by the ISL28025 auxiliary channel. The primary shunt channel of the ISL28025 is used to monitor current, while the Vbus channel of the ISL28025 measures the total voltage of the battery pack. If an overcurrent or overvoltage condition crosses the threshold set for the analog comparators, the ISL28025 alerts the MCU with SMBAlert1, and SMBAlert2 disconnects the battery from the charger circuit or load via the NMOS at M2 and the PMOS at M1 driven by Q1. The current measurement is very accurate and can also be used as a fuel gauge for the battery pack. The SMBAlert2 line can also be used to wake up the system when in sleep mode.