Standby RAM Brownout Detect

[jeromebrown_at_]

Has  Anyone used Standby RAM Brownout Detect on the MPC5777C?

Is there any additional information on how reliable it is?

[lukaszadrapa]

Hi,

the data retention in Standby RAM is guaranteed down to 0.95V as specified in datasheet. Also the brownout detect should work as described. There are no known issues.

Are you facing any troubles with this feature?

Regards,

Lukas

[jeromebrown_at_]

Lukas,

I am trying to use it as signal to the Micro to Clear the Ram and reboot

the device.

Can it be used in this Fashion?

[lukaszadrapa]

Hi Jerome,

this flag can be used to detect if the RAM memory contains valid data after reset or power-on.

If the STND_BY_RAM_BR_DETCT is set after power-on, it says that the content of RAM has been lost (voltage fell below 0.95V on VSTBY). So, whole RAM including standby RAM must be initialized due to ECC. Then you can initialize the standby RAM, so it contains valid useful data. Then clear the STND_BY_RAM_BR_DETCT flag (first write 1 to STND_BY_RAM_BR_CLR and then write 1 to STND_BY_RAM_BR_DETCT).

After next boot (after next power-on or reset), just check the flag STND_BY_RAM_BR_DETCT. If it is 0, the content of standby RAM is valid. You do not need to initialize standby RAM, initialize only the rest of the RAM.

Regards,

Lukas