SLAU847D October 2022 – May 2024 MSPM0L1105 , MSPM0L1106 , MSPM0L1227 , MSPM0L1228 , MSPM0L1228-Q1 , MSPM0L1303 , MSPM0L1304 , MSPM0L1304-Q1 , MSPM0L1305 , MSPM0L1305-Q1 , MSPM0L1306 , MSPM0L1306-Q1 , MSPM0L1343 , MSPM0L1344 , MSPM0L1345 , MSPM0L1346 , MSPM0L2227 , MSPM0L2228 , MSPM0L2228-Q1
A certain minimum decoupling capacitor will be required on the VBAT supply pin. This is mainly for noise immunity, but also to supply peak currents during switching activity on a high impedance power source. Specifically, the tamper I/O pins can create fairly high switching noise.
Due to the required decoupling cap, the loss of the VBAT supply will happen in a ramp, rather than a step function, even when the VBAT battery will suddenly be removed from the system. Due to the ramp, the VBAT-DET circuit will observe the loss of the VBAT domain and isolate all signals coming from the VRTC domain.