at90ls4433 ATMEL Corporation, at90ls4433 Datasheet - Page 47

• Manufacturer Part Number: at90ls4433
• Description: At90s4433 8-bit Avr Microcontroller With 4k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Prevent EEPROM
Corruption
1042H–AVR–04/03
During periods of low V
age is too low for the CPU and the EEPROM to operate properly. These issues are the
same as for board-level systems using the EEPROM, and the same design solutions
should be applied.
An EEPROM data corruption can be caused by two situations when the voltage is too
low. First, a regular write sequence to the EEPROM requires a minimum voltage to
operate correctly. Second, the CPU itself can execute instructions incorrectly if the sup-
ply voltage for executing instructions is too low.
EEPROM data corruption can easily be avoided by following these design recommen-
dations (one is sufficient):
1. Keep the AVR RESET active (low) during periods of insufficient power supply
2. Keep the AVR core in Power-down sleep mode during periods of low V
3. Store constants in Flash memory if the ability to change memory contents from
voltage. This can be done by enabling the internal Brown-out Detector (BOD) if
the operating speed matches the detection level. If not, an external low V
Reset Protection circuit can be applied.
will prevent the CPU from attempting to decode and execute instructions, effec-
tively protecting the EEPROM Registers from unintentional writes.
software is not required. Flash memory cannot be updated by the CPU and will
not be subject to corruption.
CC
, the EEPROM data can be corrupted because the supply volt-
AT90S/LS4433
CC
. This
CC
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