AD7770 Transfer function

Question

Hi 
 
 AD7770 ADC data can be read by the following table given in datasheet

Please let us know how can we calculate the ADC digital output code for the different voltage levels(2.1168V, 2.16V, 2.2032V) 
 As per our design we are external Vref of 3.3V 
 Please provide the digital output code for the full scale range of 3.3V 
 Thanks and Regards 
 Abishek V

JoanOrtega · Accepted Answer

Hi Abishek 
 
 The following function is the one I am currently using and it seems to work properly. 
 ref= value of the reference 
 raw_code= the 24bits data 
 voltage= pointer where the calculated voltage is stored. 
 
 void ad7771_data_to_voltage(double ref, uint32_t *raw_code, double *voltage) { if((*raw_code <= 0x7FFFFF) && (*raw_code >= 0x00)) { *voltage = (double)(*raw_code * (ref/16777216.0)); } else { *voltage = (double)((*raw_code * (ref/16777216.0))-ref); } }

JoanOrtega · Answer

XLS 
 This excel file will help you calculate the voltage. You only need to insert in the blue cell the value read from the ADC. 
 Regards 
 Joan

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AD7770 Transfer function

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