SLAAEG4 October 2023 MSPM0C1104 , MSPM0L1306
The power-on reset (POR) monitor supervises the external supply (VDD) and asserts or de-asserts a POR violation to SYSCTL. During cold power-up, the device is held in a POR state until VDD passes the POR+. Once VDD has passed POR+, the POR state is released and the bandgap reference and BOR monitor circuit are started. If VDD drops below the POR- level, then a POR- violation is asserted and the device is again held in a POR reset state.
The POR monitor does not indicate that VDD has reached a level high enough to support correct operation of the device. Rather, it is the first step in the boot process and is used to determine if the supply voltage is sufficient to power up the bandgap reference and BOR circuit, which are then used to determine if the supply has reached a level sufficient to for the device to run correctly. The POR monitor is active in all power modes including SHUTDOWN, and cannot be disabled. (The POR triggered waveform is shown in Section 3.2.3).