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 Load Transient Response Test...

A. Select "Load Transient Response" in the Control Panel.

B. Check the load transient settings and adjust them if necessary. The settings include their initial current level, the maximum current level, the rise time of the pulse, the duration (pulse width), and the fall time.

Here we’ve clicked on "lout" and adjusted the load transient to step from 300mA to 1.5A, with a duration of 2ms.  The rise and fall times are unchanged at 50us.  In the Control Panel, the overall simulation time is set to 3ms.

C.  Run the test by clicking the Control Panel button, then click "GO."  When the simulation has completed, the Status will indicate that it is "Ready." 

D. Click on the output voltage probe, and see the waveform there due to the load transient.

It is reasonably well damped, with just one cycle of ringing. We can zoom in on a section in the waveform, and see the output voltage ripple due to the switching action of the regulator. In the zoomed-in view, we can take advantage of the built-in calculator to measure the peak-to-peak output voltage ripple at full load, a little less than 32mV.