選擇合適的系列電壓基準源的絕對精度電壓輸出
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Max Error Target
Each example is analyzed, focusing on the specifications that apply to that particular design. The results of this analysis, along with the results of the previous section, are summarized in an error budget in Table 5.
It is most convenient to do the error-budget accounting in ppm, although this could be done equivalently in other units such as %, mV, or LSBs. It's important to apply the proper scaling and to use the proper normalization factor to get the correct error values. Reference error terms can be equivalently calculated relative to the reference voltage or the DAC output voltage. For example, if we assume a reference error of 2.5mV (noise, drift, etc.) and a reference voltage of 2.5V, we get the following:
Reference Output Error = 106 × 2.5mV / 2.5V = 1000ppmIf we assume that the DAC output amplifier has a gain of 2.0, both the error and the reference voltage are scaled, so we get the same result at the DAC output (5V full-scale range):
DAC Output Error = 106 × (2.5mV × 2) / (2.5V × 2) = 1000ppmTable 5. Error-Budget Analysis
Main Design Objectives | ||||
Example Application | ||||
Reference Initial Error | ||||
Reference/DAC Post- Calibration Error | ||||
Reference Tempco Error |
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