product brief
[last sentence]
The AVR® SD provides a dual-core lockstep CPU, Single-Error Correcting and Double-Error Detecting (SECDED) ECC on Flash, EEPROM and SRAM, Error Controller, and immutable boot for functional safety.
Now why on earth would they choose to use "SD"? I read the thread title and thought "AVR with SD card interface?" or even "AVR in the physical form of an SD card?"
The product brief was 404'd.