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In the figure below is shown the dynamic behavior of an SCR in terms of its current during switch off. I'm interested in calculating the maximum reverse current (iR in the plot). The parameters that I know are the common one that datasheet usually report: Vrrm, Irrm, trr..

What I don't know is actually Qrr that would have been useful.

Iak of an SCR during switch off process

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  • \$\begingroup\$ Parameter descriptions are here: st.com/content/ccc/resource/technical/document/application_note/… If that doesn't help, we need a more specific question. \$\endgroup\$ – Mattman944 Apr 16 at 21:11
  • \$\begingroup\$ @Mattman944 I hope that now it's more clear! \$\endgroup\$ – Nick Lombardo Apr 16 at 21:23
  • \$\begingroup\$ You can not calculate that. If the reverse recovery parameters can not be obtained from the manufacturer, the device is not suitable for applications where that matters. \$\endgroup\$ – Charles Cowie Apr 16 at 21:56
  • \$\begingroup\$ @CharlesCowie I suspected that. Though what I noted is that its magnitude is proportional to diR/dt so probably I can derive some coefficient from experimental evaluations? My final purpose is to characterize a specific SCR device \$\endgroup\$ – Nick Lombardo Apr 16 at 22:30
  • \$\begingroup\$ With the proper equipment, you can test any given device to determine the reverse recovery characteristics, but I don't think you can use the characteristics of one device to accurately predict the characteristics of a different device. \$\endgroup\$ – Charles Cowie Apr 17 at 1:59

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