11.3.3 Preventing Flash/EEPROM Corruption

A Flash/EEPROM write or erase can cause memory corruption if the supply voltage is too low for the CPU and the Flash/EEPROM to operate correctly. These issues are the same on board-level systems using Flash/EEPROM. The internal or an external Brown-out Detector (BOD) is recommended to ensure that the operating voltage is high enough.

Two circumstances may cause Flash/EEPROM corruption when the voltage is too low:
  1. A regular write sequence to the Flash, requiring a minimum voltage to operate correctly.
  2. The CPU can execute instructions incorrectly when the supply voltage is too low.

The chip erase does not clear fuses. If the BOD is enabled by fuses before starting the Chip Erase command, it is automatically enabled at its previous configured level during the chip erase.

Refer to the Electrical Characteristics section for Maximum Frequency vs. VDD.

Attention: Taking the following measures may avoid Flash/EEPROM corruption:
  1. Keep the device in Reset during periods of insufficient power supply voltage. Do this by enabling the internal BOD.
  2. The Voltage Level Monitor (VLM) in the BOD can be used to prevent starting a write to the EEPROM close to the BOD level.
  3. If the detection levels of the internal BOD do not match the required detection level, an external VDD Reset protection circuit can be used. If a Reset occurs while a write operation is ongoing, the write operation will be aborted.