{"id":4481,"date":"2020-06-25T08:00:50","date_gmt":"2020-06-25T06:00:50","guid":{"rendered":"http:\/\/medtech-ingenieur.de\/?p=4481"},"modified":"2021-08-06T14:34:41","modified_gmt":"2021-08-06T13:34:41","slug":"worst-case-analyse-mit-ltspice","status":"publish","type":"post","link":"https:\/\/medtech-ingenieur.de\/en\/worst-case-analyse-mit-ltspice\/","title":{"rendered":"Worst-case analysis with LTSpice"},"content":{"rendered":"

When developing circuits, one always has to deal with components that have tolerances that can influence the circuit's functionality to a greater or lesser extent. To determine the influence of component tolerances on the output variables of interest, a simulation with LTSpice is a good option. Common methods such as Monte Carlo analysis are already integrated into LTSpice. This article focuses on a simplified, significantly faster analysis method, worst-case analysis, which considers only the extreme limits of component tolerances.<\/p>\n

Worst case with a simple power source<\/h3>\n

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In this example you can see the construction of a simple current source with an npn transistor, 3 resistors (R1<\/strong>, R2<\/strong> and R3<\/strong>) and a load resistor (R_LOAD<\/strong>). The current through the load resistor is \u201cload-independent\u201d and limited to approximately 1.84 mA<\/strong> set.<\/p>\n

To determine the influence of resistance tolerances of R1<\/strong>, R2<\/strong> and R3<\/strong> on the load current by R_LOAD<\/strong> To determine this, LTSpice offers several ready-made functions to vary component values across multiple simulation runs.<\/p>\n