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TPSI3050-Q1: Is it possible to power an AMC1311 high side with the Iaux power output?

Part Number: TPSI3050-Q1
Other Parts Discussed in Thread: AMC1311, TPSI3050


We are working on a board with a 400V power input. We have an isolated 5V section to power our MCU and a few other LV Circuits. We need to monitor the voltage of our supply, which we are planning to do with the AMC1311DWVR. The original plan was to use the SN6501DBVR transformer driver to create the isolated 5V supply. However looking at the datasheet for the TPSI3050 isolated gate driver it looks like it might be possible to use the VDDM to power the high side supply.  There are two main complications that I can see. First, The second issue is I am not sure the auxiliary supply is going to be an adequate power source for a sensitive voltage monitor. Second, the TPSI3050 is floating VDDM (and VDDH) above the 400V supply to drive high side N-channel MOSFETs meaning that if we followed the recommended voltage divider configuration in the AMC1311 datasheet we would have a potential difference of ~400V. I was thinking this could be solved by switching the 20.5k sense resistor and the 3.9MOhms of series resistance such that there is only a small voltage difference between the the sense resistor and the AMC1311.  Can you please weigh in on this?