kingearlkwan
Junior Member level 1
Hi All,
One way to trigger the SCR is by dV/dt triggering.I understand the part that when a forward bias voltage is applied between anode to cathode, J1 and J3 junction is forward bias and J2 is reverse bias. This triggering occurs because of the junction capacitance in J2. a high slew rate (dv/dt) means high current on this junction by i=C(dv/dt).
My question is how is the SCR is turned on by the capacitance of J2?Can anyone explain the current flow that happens and how the Q1 and Q2 transistors of the SCR are turned on by this kind of triggering? It well help me better understand if I can clearly imagine what is really happening in the circuit. How is the pnp Transistor turned on if there is no path way to its base junction since the NPN transistor in which it is connected is still off. I'm not sure if I understand how the circuit behaves completely.
Your inputs are highly appreciated.
Thanks!
- - - Updated - - -
Am I correct that the Q2 transistor is triggered by the charging current during transient in capacitor?initially the capacitor acts like a short circuit at the start.
One way to trigger the SCR is by dV/dt triggering.I understand the part that when a forward bias voltage is applied between anode to cathode, J1 and J3 junction is forward bias and J2 is reverse bias. This triggering occurs because of the junction capacitance in J2. a high slew rate (dv/dt) means high current on this junction by i=C(dv/dt).
My question is how is the SCR is turned on by the capacitance of J2?Can anyone explain the current flow that happens and how the Q1 and Q2 transistors of the SCR are turned on by this kind of triggering? It well help me better understand if I can clearly imagine what is really happening in the circuit. How is the pnp Transistor turned on if there is no path way to its base junction since the NPN transistor in which it is connected is still off. I'm not sure if I understand how the circuit behaves completely.
Your inputs are highly appreciated.
Thanks!
- - - Updated - - -
Am I correct that the Q2 transistor is triggered by the charging current during transient in capacitor?initially the capacitor acts like a short circuit at the start.