ADS7052: Works abnormally when the temp is lower than -14℃

Hi Team,

My customer use ADS7052IRUGR and found that it works abnormally when the temp is lower than -14℃.

Test environment: Thermometer box, which could keep temp  to -25℃~0℃

Test method: Provide 2.048V DC signal to the input of ADS7052 and then read the value of ADC output through FPGA.

SCH：

Test Result:

Customer has confirmed that the input voltage(2.048V), the DVDD(3.3V) and AVDD(3.3V) are all normal during the temperature( -25℃~0℃).

However, when the temp is lower than -14℃, the output of the ADS7052 is abnormal. You could see that the result is only 600 and 0.311V...

It seems that ADS7052 is abnormal. Could you please kindly give some advice about this?

Thanks！