SNVSB03D December 2018 – January 2020 TPS3840
A typical application for the TPS3840 is to monitor a voltage rail and switch the power to a back-up battery if the main supply is in undervoltage condition. Because systems that utilize a back-up battery tend to require low quiescent current, TPS3840 serves as the perfect solution as this device only requires 350 nA typically. The TPS3840 monitors the main power rail via the VDD pin and when the main power rail falls, the RESET output asserts causing a switch to close on the back-up battery rail. The diodes provide an ORing logic function to prevent reverse leakage and to allow either rail to connect to the output depending on the status of the main voltage rail.