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AMC0106M25: Drift in measured values at elevated device temperature

Arttu Räsänen
Prodigy 30 points

Part Number: AMC0106M25

Dear TI,

we're using the AMC0106M25 isolated ADC in our isolated Wired M-Bus interface project.

On the isolated side, the AMC0106M25 is measuring the current flowing through the M-Bus via a low-side shunt resistor. On the non-isolated side, the DOUT and CLKIN are interfaced with the MCU (RP2040) via 47R series termination resistors. 

On our prototype we have been puzzled by the behaviour of the AMC0106M25 with respect to temperature changes. We have noticed an increase in measured current values when the PCB or the chip became warm. Even relatively small temperature increases (e.g. warming the chip with a finger, etc.) started showing exaggerated current measurements.

We managed to work around the problem by soldering a 47pF/0402 ceramic capacitor between the CLKIN pin and DGND. This seemed to help with the temperature drift problem, although we are not able to explain why. Do you have any ideas?

  • 0
    TI__Guru 60142 points

    Hi, 

    Can you please help quantify what magnitude of increase you see? 

    If you have not done so already, can you please probe CLK and DATA near the input of the SDFM and check for magnitude and timing violations compared to the datasheet?