commutationthyristor
In datasheets, they give this value at a certain operation point (voltage, current, and di/dt). My question is… What are the effects of changing these parameters.
For example, if di/dt is increased, will this make the circuit commutated turn-off time less? Or is the circuit commutated turn-off time an inherent property of the thyristor?
Thanks!
The 180Ω resistor will probably need to be altered for 12VAC, what value it needs to be depends on the minimum trigger/latching current needed for the main triac. Also, a 0.25W resistor is only suitable if the wattage doesn't exceed 0.25W, so you need to calculate max voltage across it times current through it.
This Fairchild app note is worth a read for deciding on the values of components to use.
For a resistive load the circuit shown below:
The relevant part of this note with the formulas is:
Triac Driving Requirements
Figure 2 shows a simple triac driving circuit using the MOC3011M. The maximum surge current rating of the MOC3011M sets the minimum value of R1 through the equation:
R1 (min) = Vin(pk)/1.2A
If we are operating on the 115 Vac nominal line voltage, Vin (pk) = 180 V, then:
R1(min) = Vin(pk)/1.2A = 150 ohms.
In practice, this would be a 150 or 180 ohm resistor.
If the triac has IGT = 100 mA and VGT = 2 V, then the voltage Vin necessary to trigger the triac will be given by:
VinT = R1 * IGT + VGT + VTM = 20 V.
vtingole
Best Answer
Some parameters do effect others. For example, see the following from the General Electric SCR Manual 5th ed. 1972