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Decoding the i2c data to voltage

Category: Hardware
Product Number: LTC2497

hi team 

We are using the LTC2497 in single-ended mode, with IN- grounded and a reference voltage (Vref) of 2.5V. Channel 11 is connected to an input voltage of 0.85V. The I2C data read from the LTC2497 is 0xAD47C0, which translates to output_reg[21:6] = 0x00B51F = 46367.

Based on the calculation:
1 * (46367 / 65535) * 0.500 * 2.500 = 0.884V


However, the input voltage remains constant at 0.85V. While other channels are being used to calculate current from other devices, we are using this channel specifically to cross-check the calculations. Despite this, we observe a discrepancy in the calculated result.
Could you confirm if there is an issue with the data decoding or calculations?

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  • Hi  ,

    The voltage that you have calculated based on the output code is correct. 

    However, the input voltage remains constant at 0.85V.

    Have you tried measuring in the actual CHx pins just to make sure that the ADC input voltage is really 0.85V?

    Have you tried using other channels with the same input voltage? If yes, are they showing the same behavior?

    For debug, kindly try using a different input voltage and see what the output code would be. 

    Is it also possible to share your schematic so we could also check for potential errors causing this behavior?

    Regards,

    JC

Reply
  • Hi  ,

    The voltage that you have calculated based on the output code is correct. 

    However, the input voltage remains constant at 0.85V.

    Have you tried measuring in the actual CHx pins just to make sure that the ADC input voltage is really 0.85V?

    Have you tried using other channels with the same input voltage? If yes, are they showing the same behavior?

    For debug, kindly try using a different input voltage and see what the output code would be. 

    Is it also possible to share your schematic so we could also check for potential errors causing this behavior?

    Regards,

    JC

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