Figure 72 shows a simplified circuit diagram of a battery test system. Use the internal reference (2.5 V) and gain of 1 for an output range of 2.5 V. The reference divider is 1. Select the 16-bit DAC80502 for the best accuracy. The typical value of the TUE is 0.02%FSR, as specified in the Typical Characteristics table. The absolute error at the DAC output includes the error from the reference, the error from the DAC, and the temperatures drifts of offset error, gain error, and reference. Ignore the load regulation, line regulation, and long-term drift of the reference as compared to the initial accuracy and temperature drift. Write the total TUE at the DAC output, as given in Equation 2.
Convert the INL value in LSB to %FSR using Equation 3.
Convert the temperature drift values in ppm/°C to %FSR using Equation 4.
Calculate the total error after the offset and gain of DAC are calibrated using Equation 5
The total error at the DAC output calculated using the previous equations is 0.112%FSR before calibration, and 0.05%FSR after calibration. For better accuracy, perform a temperature calibration. Figure 73 and Figure 74 show the drift in the internal reference voltage and TUE, respectively over 0°C to 100°C.