ADuCM355 internal temp sensor transfer function

Hi,

1) Are you using the InitAfeADC() function in page 62 of UG-1262?

2) You can use Sinc2 filter by enabling it as below:

pADI_AFE->AFECON &= (~(BITM_AFE_AFECON_SINC2EN)); // Clear AFECON[16]

pADI_AFE->AFECON |= BITM_AFE_AFECON_SINC2EN; // Set AFECON[16]

Result shall be obtained from SINC2DAT instead of ADCDAT.

Yes, of course the AFE is configured properly. The provided transfer function is incorrect. This isn't the first time I've found mistakes in the data sheet or library code.

I've tried many different settings and some change the output value. For example, if I change the gain, the output value is vastly different. If the transfer function was correct, then the output should be the same, because the gain setting is included in the calculation.

Hi,

 As per the design, this is the correct transfer function.

May I know if you have done ADC calibration (updated  ADCOFFSETTEMPSENS0 and ADCGAINTEMPSENS0 ) before measuring temperature?

No, I have not done a calibration. I thought those values were factory set? Does it affect the result that much? For example, I'm reading around 900C and a board mounted temp sensor is reading around 25C.

The ADCOFFSETTEMPSENS0 register has a value in it of 0x7F53 (data sheet says this is supposed to be 0).

The ADCGAINTEMPSENS0 register has a value in it of 0x4000.

Also, I see no procedure in the data sheet for calibrating TEMPSENSOR0. Further, the data sheet does not say that it must be done.

The datasheet says that values in the ADCOFFSETTEMPSENS0 and ADCGAINTEMPSENS0 registers will be used for temperature calculation:

Are you using the example in Github : ad5940-examples/examples/AD5940_Temperature at master · analogdevicesinc/ad5940-examples (github.com)