During periods of low VDD, the Flash program or EEPROM data can be
corrupted if the supply voltage is too low for the CPU and the Flash/EEPROM to operate
properly. These issues are the same on-board level systems using Flash/EEPROM, and the same
design solutions may be applied.
A Flash/EEPROM corruption can be caused by two situations when the voltage is too low:
- 1.A regular write sequence to the
Flash, which requires a minimum voltage to operate correctly.
- 2.The CPU itself can execute
instructions incorrectly when the supply voltage is too low.
See the
Electrical Characteristics section for Maximum Frequency vs.
V
DD.
Attention: Flash/EEPROM corruption can be avoided by taking these measures:
- 1.Keep the device in Reset during
periods of any insufficient power supply voltage. Do this by enabling the internal
Brown-out Detector (BOD).
- 2.The voltage level monitor 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 low
VDD Reset protection circuit can be used. If a Reset occurs while a
write operation is ongoing, the write operation will be aborted.