ATTINY15 ATMEL [ATMEL Corporation], ATTINY15 Datasheet - Page 38

• Manufacturer Part Number: ATTINY15
• Manufacturer: ATMEL [ATMEL Corporation]

Preventing EEPROM
Corruption
38
ATtiny15L
The calibrated oscillator is used to time EEPROM. In Table 16 the typical programming
time is listed for EEPROM access from the CPU.
Table 16. Typical EEPROM Programming Times
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
Parameter
EEPROM write
(from CPU)
voltage. This can be done by enabling the internal Brown-out Detector (BOD) if
the operating voltage 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.
Number of Calibrated RC
Oscillator Cycles
CC
, the EEPROM data can be corrupted because the supply volt-
8192
Min Programming
4.6 ms
Time
Max Programming
8.2 ms
Time
CC
. This
CC
1187D–12/01