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ADuCM360 ADC calibration using AVDD as reference

Question asked by Aladdin on Mar 14, 2013
Latest reply on Mar 20, 2013 by MMA

Hello everyone


I am using ADuCM 360 with its 2 ADC converters. The AVDD is used as reference voltage for the ADCs and gain of 1. The readings of the ADCs contains a slight error of 20 mV. It is stated in the data sheet a calibration is needed when AVDD is used as a reference to update ADCxVDDGN. I did the calibration in the initialization of the ADC as follow


AdcMski(pADI_ADC0,ADCMSKI_RDY,1);              // Enable ADC0 ready interrupt source 

AdcFlt(pADI_ADC0,157,8,FLT_NORMAL|ADCFLT_NOTCH2|ADCFLT_RAVG2); // ADC filter set for 4.5Hz update rate

AdcRng(pADI_ADC0,ADCCON_ADCREF_AVDDREF,ADCMDE_PGA_G1,ADCCON_ADCCODE_INT); // VDD reference selected, Gain of 1, Signed integer output

AdcGo(pADI_ADC0,ADCMDE_ADCMD_IDLE);       // Place ADC0 in Idle mode

AdcGo(pADI_ADC0,ADCMDE_ADCMD_INTOCAL); // Internal zero offset calibration


AdcGo(pADI_ADC0,ADCMDE_ADCMD_INTGCAL);  // Internal full scale gain calibration to update ADC0VDDGN



but still the output readings of the ADC are not accurate. please can any one help me, is this calibration steps are correct? 


Many thanks in advance