Henrik, I don't think I've heard of this behavior in this device. However, as you've described it, I think it's likely that the device has gone through some sort of reset. With a surge (or negative surge) of the supplies, it's possible that there's been some problem in the power-on-reset and the device has triggered the reset. To be sure, I would just trigger the event and then read back the registers to see that they have been reset back to the default values. My first suggestion would have been to see if we could protect the device a little bit better to prevent this type of reset from happening. Maybe, increasing the supply capacitance to prevent any dips in supply, or using lower voltage rated TVS, or lower forward voltage Schottky diodes might help. However, I'm just guessing without having seen your schematic. In some devices a reset is tracked in the register to indicate when the device may have loaded internal registers at the startup. However, that's not the case in the DAC8775. In general, the reset is how you would clear an alarm. As for the read of the UBT/UTGL, writing a non-default value into the user register would probably work fine. I had been thinking about other monitoring flags that might help. If the CRC or WDT were enabled by default, then you'd get the error the first time either of these failed during a reset. However, with neither enabled by default, you wouldn't get the error for either case. Enabling either and then going through a reset would just cause a write error, but I don't think it would get flagged. Joseph Wu
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