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Tool/software:
Hi
I was giving differential voltage output from the current sensor to the differential pins of EADC pins. I need to calculate total EADC error calculation for the microcontroller. Can you provide a formula to calculate the Total ADC error. and ADC count calculation.
And for the single ended ADC pin i Calculated the total error using the following formula. i would like to get the correct formula from your side.
DATASHEET Values
ADC12 INL integral nonlinearity, end point –3.9 ±2 4.5 LSB
ADC12 DNL differential nonlinearity(2) –0.8/+2.4 LSB(Typical Value)
Formula,
TUE= SQRT (INL^2+DNL^2)
Hello Lithiyashree,
Are you asking about the Error ADC or the 12-bit ADCs calculation? The Error ADC and the 12-bit ADC or two different pins that measure signals differently. The Error ADCs are primarily used as the input to the PID filter for the control loop. The Error ADCs have faster sense so the control loop has a fast transient response. The 12-bit ADCs are used for general signal measurement or as a comparator to trigger a fault. The 12-bit ADCs typically have sampling rate of 268kS/s, which is considerably slower than what the control loop will require.
Please see this E2E post as an example on how the 12-bit ADC values are calculated in the Half Bridge LLC firmware: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1343727/ucd3138allcevm150-calculations-for-sensing-of-primary-current-signal-ips-and-calibration-in-firmware-for-the-same/5170546?tisearch=e2e-sitesearch&keymatch=%25252525252525252520user%2525252525252525253A525510#5170546
Regards,
Jonathan Wong
Hi jonathan ,
Thank for the reply, i need calculation for total ADC error and ADC count ,for Both single ended ADC pin and Differential EADC pin.
we are giving the output of the current sensor to the microcontroller to the differential ADC pin. And another current sensor output to the single ended ADC pin
You can refer to the datasheet for the error type.
Please refer to the following thread for the total error calculation.