2 Fixed Errata

One erratum in the non-A MSP430F67xx devices was the AUXPMM1 errata that is listed in the device erratasheets. This erratum covers the AUX module, which is a module that allows switching the supply that powers the chip from DVCC/AVCC to AUXVCC1 or AUXVCC2 if DVCC/AVCC falls below a certain voltage threshold. After DVCC/AVCC rises above the associated threshold, the chip should automatically switch back to being powered by DVCC/AVCC. However, in this erratum, there could be a case where the AUX module would not switch back to DVCC when it is running from AUXVCC1 or AUXVCC2. In particular, when the system is running with the AUXVCC1/AUXVCC2 supply after DVCC/AVCC is lost, and if the AUXVCC1 voltage goes lower than the SVSH setting for POR but above the BORH level, the system cannot switch back to DVCC after DVCC ramps back up again. In a typical application, DVCC/AVCC is powered from mains through a power supply, while AUXVCC1 or AUXVCC2 are connected to batteries. As a result of this configuration and this erratum, the chip would continue to be powered from the battery despite Mains being present. This would eventually lead to the battery being depleted. In the MSP430F67xxA devices, this erratum has been fixed, which prevents this sequence of events from happening.

Another erratum fixed in the MSP430F67xxA devices was the RTC8 erratum mentioned in device erratasheets. This particular erratum is most pertinent to the high-accuracy poly-phase metering SoCs, because they have the RTCCAP functionality present. For this RTCCAP feature, whenever there is an event (a rising or falling edge) detected on any of the RTCCAP pins, the RTC time when this occurs is logged. In a typical application, the RTCCAP pins could be connected to a meter case so that whenever someone tries to open the case, a switch would trip and send a rising or falling edge signal to the RTCCAP pin. From there, the time of this case tamper event could be logged.

In the F67xx devices, the backup subsystem that includes the RTC is powered independently by AUXVCC3 (instead of by DVCC/AVCC, AUXVCC1, or AUXVCC2). Because the rest of the chip does not need to be powered, this reduces the current draw when only the RTC needs to be functional. However, due to the RTC8 erratum, the tamper detection function triggered by the RTCCAP0 and RTCCAP1 pins cannot get a correct time stamp value when DVCC and AUXVCC1 are off. To ensure that the correct time stamp is obtained, DVCC and AUXVCC1 should not be off. As a result, the current draw is increased when this feature is necessary. For the MSP430F67xxA devices, this erratum is fixed so that the correct time stamp can be captured with only voltage at AUXVCC3 present, thereby preventing the increase in current from having to power the rest of the chip via DVCC/AVCC, AUXVCC1, or AUXVCC2.