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UCC21710-Q1: The maximum fluctuation range of DAPWM is 0.05,how to design to ensure the accuracy of sampling quantity

user6133225
Prodigy 40 points
Part Number: UCC21710-Q1

The maximum fluctuation range of DAPWM is 0.05. Assuming that the sampling high voltage is 600V,

Suppose that the upper sampling resistance of the inlet AD port is 800k and the lower sampling resistance is 3.3k.
 the actual value of AIN at the inlet of AD port is 2.46v,It's about 2.5 volts ,

In normal state, APWM output duty cycle is 0.5, but APWM output duty cycle may fluctuate to 0.55


then in the software
the value of AIN at the inlet of AD port is 2.25v.
Multiplied by the magnification factor, 0.25*(800+3.3)/3.3=60.856V ,the sampling voltage accuracy is sixty volts, am I wrong?

  • 0
    TI__Expert 4875 points

    Hello,

    Yes, you can estimate that the 2.25 V at APWM (based on 0.55 duty) would result in a voltage error of around 10%. However, the voltage accuracy can be easily improved by calibration at a single point at room temperature. This will compensate for part to part process variation or if your system is going to be operating in a high-temperature environment, calibration at temperature will also improve your accuracy. 

    Regards,

    Audrey