SLAZ102AB October 2012 – May 2021 CC430F6137
PMM Module
Functional
False SVSxIFG events
The comparators of the SVS require a certain amount of time to stabilize and output a correct result once re-enabled; this time is different for the Full Performance versus the Normal mode. The time to stabilize the SVS comparators is intended to be accounted for by a built-in event-masking delay of 2 us when Full Performance mode is enabled.
However, the comparators of the SVS in Full Performance mode take longer than 2 us to stabilize so the possibility exists that a false positive will be triggered on the SVSH or SVSL. This results in the SVSxIFG flags being set and depending on the configuration of SVSxPE bit a POR can also be triggered.
Additionally when the SVSxIFGs are set, all GPIOs are tri-stated i.e. floating until the SVSx comparators are settled.
The SVS IFG's are falsely set under the following conditions:
1. Wakeup from LPM2/3/4 when SVSxMD = 0 (default setting) && SVSxFP=1. The SVSx comparators are disabled automatically in LPM2/3/4 and are then re-enabled on return to active mode.
2. SVSx is turned on in full performance mode (SVSxFP=1).
3. A PUC/POR occurs after SVSx is disabled. After a PUC or POR the SVSx are enabled automatically but the settling delay does not get triggered. Based on SVSxPE bit this may lead to POR events until the SVS comparator is fully settled.
For each of the above listed conditions the following workarounds apply:
1. If the Full Performance mode is to be enabled for either the high- or low-side SVS comparators, the respective SVSxMD bits must be set (SVSxMD = 1) such that the SVS comparators are not temporarily shut off in LPM2/3/4. Note that this is equivalent to a 2 uA (typical) adder to the low power mode current, per the device-specific datasheet, for each SVSx that remains enabled.
2. The SVSx must be turned on in normal mode (SVSxFP=0). It can be reconfigured to use full performance mode once the SVSx/SVMx delay has expired.
3. Ensure that SVSH and SVSL are always enabled.