Posted on May 17, 2011 at 15:03Hello floodever,
from your description, the problem is not very clear. I guess that you mean the following:
- the RAM shall keep the data you have written previously, even if the supply voltage is going down.
Is this correct ?
If yes, then you need to consider that keeping the RAM content cannot be guaranteed below 2.6V. It is undefined what happens to the RAM below this voltage.
In order to keep data over a voltage brown out, you need to
- either ensure that the VDD of the micro does not drop below 2.6V during this time
- or use the internal NVM (data EEPROM) to store the data. It then is important how frequently you update the concerned data in the RAM.
- If it is updated rarely (let's say up to 100k time during the life of the application), then you can store the concerned data directly in EEPROM
- If it is updated more frequently, you need to follow another strategy: Monitor the supply voltage and if the voltage drops below the nominal one, you need to write the concerned data to the EEPROM before the voltage falls below the minimum operating voltage of 3.0V. Of course this strategy needs correct dimensioning of the filter capacitors and low power strategy. OK before going more in depth, let us know more details. Have a good day Alexander [ This message was edited by: alexanderc on 04-06-2009 09:48 ]
