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| On the top of each screen in WEBENCH is a navigation header that indicates in which step of the design process the user is. The steps currently highlighted in red, "Analyze a Design" and "Electrical Simulation," indicate your current place in the process |
An example Startup Test...
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A. Select "Startup" in the Control Panel. Accept the default time of 5ms, and click the "GO" button to start the simulation. |
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B. After pressing "GO," you will see red waves moving in the "Simulator Control" box. The Status will state "simulating." When the simulation has completed, the Status will indicate that it is "Ready." The actual simulation time is usually a few seconds or less, though it may take a minute or so to send the data back and forth, depending on your connection speed. | |
C. Click on the V_OUT probe point. The waveform graph will update automatically if you change a compontent or value. |
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Time to achieve 5.0 volts=3.2 miliseconds.
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FEATURES of Waveform Viewer:
Under File, you may print.
Under Data, you may store a waveform and retrieve it for comparison to a subsequent simulation.
Under View, you may change between an AC and DC autoscale, reset the plot scale, show/hide individual data points, and refresh the graph.
To use a measurement cursor, click on the M1 or M2 button. Then click and drag your mouse across teh graph. The values will be updated in teh rightmost columns of the viewer. Click on the "Done" button to stop using the cursor or switch to another cursor. |
In this case, you can see that with an input voltage step of 0V to 20V in 50us, the output rises to the target value of 5V in 3.2 milliseconds, with a bit of overshoot (this is very close to what is seen on the bench).
D. The rise time can be controlled with the soft start Capacitor (Css). Change the soft start capacitor from 10nF to 12nF and run another simulation. |
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E. New Vout waveform: Use the M2 Measurement bar to measure the rise time. You can see that raising the softstart capacitor value has increased the time to reach 5 volts.
Time to achieve 5.0 volts=3.9 miliseconds.
Other WebSIM test help pages:
Load Transient Response Test help page
Loop Gain Measurement Test / Bode Plot help page |
Moving on...
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