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ADS131B04-Q1: Error calibration suggestion for ADS131B04-Q1

Songzhen Guo
Intellectual 2840 points
Part Number: ADS131B04-Q1

Hi Experts,

ADS131B04-Q1 is under evaluation on customer side. This device is used for BMS of EV/HEV. Customer need to get accuracy data for the analog input. They need calibration for ADC. 

Could you comment on the current solution and give us suggestions for calibration method? Thanks.

There is the method that used in customer: 

One channel is connected to reference voltage, the rest channels are used for sensing. 

One channel is connected to a reference voltage(such as: REF5030-Q1), all the error information and Compensation value are calculated by this channel. This error information and compensation are used for the rest channels. 

Best Regards

Songzhen Guo

  • 0
    TI__Mastermind 18900 points

    Hello Songzhen,

    Could you comment on the current solution and give us suggestions for calibration method? Thanks.

    We have a good TIPL video that discusses calibrating for gain and offset error which can be found here: https://training.ti.com/ti-precision-labs-adcs-understanding-and-calibrating-offset-and-gain-adc-systems?context=1139747-1140267-1128375-1139104-1134080 

    The offset can be calibrated using the MUX0[1:0] (or MUX1, MUX2, etc) bits in the corresponding CH1_CFG (or CH2_CFG, etc) registers to short the inputs. Then, the offset factor can be applied using OCAL1_MSB and OCAL1_LSB (or OCAL2_xxx, etc). Note, that some users like to average multiple points during calibration to cut down on noise.

    For gain calibration, one of the points during the training is not to pick values that are at or in the non-linear regions of input voltage vs. output code range. Anyways, I wouldn't recommend using that external reference voltage if it is close or exceeds the edges of the full scale range (FSR) of the ADC. In this case, the REF5xxx series wouldn't work as it is outside of all possible FSR options (i.e. 2.048V > +1.2V or -1.2V). Note, the internal test signal mode is not useful for calibration as the true input voltage is not known.

    Then, CHn_GCAL_MSB and CHn_GCAL_LSB can be used to correct for gain after using the equations.

    Best,

    -Cole