In order to avoid corrupted data, the EEPROM is protected while the power is outside of normal operating conditions. On power-up, Vcc should begin at zero and rise directly to its normal voltage and not linger below the minimum operating voltage. If Vcc falls below the minimum operating voltage for the EEPROM, the brown-out reset will bring Vcc down to 0V allowing both devices to be reset together. In order to maintain proper operating conditions, the operating voltage should always be higher than the minimum allowed voltage for the entire write cycle to ensure data integrity.