I am studying SCR gate drivers at the moment and I would like to understand their fundamentals.
Looking at a SCR datasheet (for example, this one section 7 or this application note fig 6 p4,) one see that long "trailing" (or back porch) current is demanded on the gate after the SCR is turned on.
My understanding is that the SCR remains on after switching as long as a large enough current (given in the datasheet) is flowing between A and K.
Why is a trailing current demanded on the gate?
Any explanation or pointer toward a reference that describe the reason for a trailing current on an SCR gate will be welcome.