Robust failsafe system for extending backup battery life in real-time low-power MCU systems

A method and system are provided for supplying power to a backup power domain by connecting a battery voltage to a power supply terminal of a backup power domain in a low-power microcontroller when a primary power supply voltage is present during a start-up mode, detecting application of the primary power supply voltage to the low-power microcontroller at a predetermined safety voltage level, and activating a selection control circuit to supply power to the backup power domain in the low power microcontroller from the primary power supply voltage or a backup power supply voltage based on a software controlled configuration bit, wherein the selection control circuit is configured to connect the primary power supply voltage to the power supply terminal of the backup power supply domain when the primary power supply voltage is less than the battery power supply voltage in response to the software controlled configuration bit having a first user selected value. 提供一种用于通过以下方式向备用电源域供电的方法和系统：在启动模式期间当主电源电压时将电池电压连接到低功率