SLAAE76B march 2023 – june 2023 MSPM0G1105 , MSPM0G1106 , MSPM0G1107 , MSPM0G1505 , MSPM0G1506 , MSPM0G1507 , MSPM0G3105 , MSPM0G3106 , MSPM0G3107 , MSPM0G3505 , MSPM0G3506 , MSPM0G3507
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 Figure 3-2).
The brownout reset (BOR) monitor supervises the external supply (VDD) and asserts or de-asserts a BOR violation to SYSCTL. The primary responsibility of the BOR circuit is to ensure that the external supply is maintained high enough to enable correct operation of internal circuits, including the core regulator.The BOR threshold reference is derived from the internal bandgap circuit. The threshold itself is programmable and is always higher than the POR threshold. During cold start, after VDD passes the POR+ threshold the bandgap reference and BOR circuit are started. The device is then held in a BOR state until VDD passes the BOR0+ threshold. Once VDD passes BOR0+, the BOR monitor releases the device to continue the boot process, and the PMU is started. (The BOR triggered waveform is shown in Figure 3-2).
When the supply voltage (VDD) drops below POR-, the entire device state is cleared. Small variations in VDD which do not pass below the BOR0- threshold do not cause a BOR- violation, and the device will continue to run. The BOR circuit is configured to generate an interrupt rather than immediately triggering a BOR reset.