AN-1378Method for Calculating Output Voltage （一个- 1378方法计算输出电压）.pdf

Application Report SNVA112A– July 2005– Revised May 2013 AN-1378 Method for Calculating Output Voltage Tolerances in Adjustable Regulators ABSTRACT When working with voltage regulator circuits, the designer is often confronted with the need to calculate the tolerance of the regulated output voltage. For fixed voltage regulators, this problem is easily managed because the required information is directly supplied on the semiconductor manufacturer’s data sheet. Contents 1 Introduction 2 2 The Commonly Encountered Circuits 2 3 The Worst Case Approach 2 4 Sensitivity Analysis 3 5 Review of Random Variable Mathematics 4 6 Statistical Variation of Resistors, Semiconductors, and Systems 4 7 The RSS Method 6 8 Random Variable Theory vs. Worst Case Over PVT 6 9 Errors Caused by Adjust Pin Current 8 10 Conclusion 9 11 References 10 List of Figures 1 Ground Referenced 2 2 Not Ground Referenced 2 3 Adjustable Regulators: Common Topologies 2 4 – Sensitivity to Resistor Variations vs.Vout