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LMP90080: sensor short detection

Jerry Chen
Expert 5110 points
Part Number: LMP90080

Hi,

Below shows the connection of RTD to LMP90080. I found, after shorting VIN_B0/B1 to B2 or shorting B0/B1/B2 to GND, in Register 0x19, Bit 7 and 6 remained as 0. It didn't show a short happened.

I want to detect the sensor short issue. What configuration I could make?

Thanks. 

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    TI__Guru**** 169535 points
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  • 0
    TI__Guru* 92735 points
    Jerry,


    I'm not exactly sure what the problem is, but I do have a guess. The sensor diagnostic flags are not always active and depend on which channel being used.

    To make sure the sensor diagnostic flags are triggered, first make sure the proper input channel is selected. If the wrong input channels are selected, the diagnostic flags will not trigger. In the schematic, it looks like the device is reading an RTD through VIN1 and VIN2. Make sure that those two inputs are selected.

    Second, take a normal reading from that channel. I believe that in some cases, sensor diagnostic flags are not triggered until after a normal data reading has taken place. As an example, using the sensor diagnostic burnout current does not occur until after a channel has completed a conversion (so that the burnout current does not affect the reading).

    If these two changes do not help trigger the flag, I'll need more information about how the device is set up and the sequence and timing of commands that are used.


    Joseph Wu