In my efforts to reduce the current consumption of my F5419 based system, I came across the SVS/SVMs. The datasheet says, that each of these modules needs 200nA when turned on, so turning all 4 off would give a benefit of 0.8µA. Which is quite a lot...
Unfortunately, if you turn all off, there is no supervision anymore (of course - besides the BOR, which will kick in much to late then), and supervision is always a good thing (well, at least in the technical world). My strategy is now like that:
1. VCC is measured with the ADC once a day.
2. If VCC is above 2.7V, which will be for the first part of lifetime (normally some years), all SVM/SVS is disabled. In my case, the Li battery is not user removable and battery is new, so there is no (imaginable) way, to have a dangerous sudden drop in voltage during this time
3. When VCC is discovered to sink below 2.7V, only the SVS High side is enabled, set to 2.16V and configured to generate a POR.
My assumptions/questions are: Low Side Supervision is not needed, because when High Side voltage is above 2.2V, it should be enough to have 1.8V on Low Side. The SVS H will prevent the system from running at dangerous low voltage levels. And finally: Why should the SVM (monitor) be used? The only advantage I can see is the overvoltage protection. Which is not needed in my case, too.
Any comments/suggestions for improvement? Am I right with my assumptions?
Regards,
Johannes