3.1.4 Battery Unit

A 5.0V battery (supercapacitor C23) is implemented to permanently maintain the VDDBU voltage. An LDO (U2 - MCP1711) is assigned to this supercap to decrease the VDDBU voltage down to 1.8V. That allows the VDDBU domain power consumption to be decreased. This LDO has an ultra-low quiescent current and can drive a very low load. For more information on the device, refer to the product webpage.

This function allows the user to shut down the MPU and the system, thus entering a low-power mode, and still keep the custom configuration that was previously set in the MPU backup area.

Jumper JP1/J2 must be in place for proper operation of the MPU, and can be removed if the user wants to bring the MPU back to the initial configuration, by resetting the General Purpose Backup Registers (GPBR).