For a battery driven application I am considering using the DA14580. The plan is to only turn on the part (from full power down) once a day over a 4 year period. In trying to get as much life span out of the battery as possible I would like to push the operation of chip below 2.5V. The datasheet clearly states that cold boot is not possible below 2.5V due to OTP corruption. It goes further to say that it is not recommended to operate below 2.35V. This raises several questions:
1. Can the DA14580 boot from an external memory below 2.5V?
2. I know the BLE stack is contained in ROM. Can the ROM operate reliably below 2.5V, 2.35V?
3. When operating below 2.35V is performance of the chip compromised in any way?
4. When operating at low voltages in buck mode, does the current draw increase? If I assume constant power I calculated the following curve. Is this accurate?
Thanks for any enlightenment you can provide.