Thyristor question

[NMNeil]

Part of my CDI project involves sending a 20mA pulse to the gate of a TYN612M thrystor to discharge the storage capacitor. The spec sheet gives a minimum of 1.5mA and maximum of 5mA to turn it on, but gives no latching current. The circuit works perfectly and the gate gets the full 20mA, but the thyristor turns off when the pulse stops.
My question is will this harm the thyristor if it only turns on, but doesn't latch?.

 

[Minder]

If an SCR is turned off , no current, I assume it turns off because there is no voltage present??
Presumably the capacitor has discharged? Show the circuit.
M.

 

[dorke]

The Thyristor will be just fine,
why do you think it may be harmed if it turns off?

And yes,there is a holding current(there always is in the datasheet!).
Once you have triggered the thyristor, for it to stay on (regardless of the gate state),
you should keep it's current(IT) above IH =20mA.

 

[73's de Edd]

If the thyristor was successfully able to dump its charge into the coil, it has done, and held up under its most critical job.
With the capacitor then discharged, there is then being no steady DC power across the thyristor to hold it latched on .

 

[NMNeil]

It's my first dealings with thyristors and I was unsure if they had the same issues as transistors or mosfets, that is if it's not in saturation you would have a lot of heat build up.
Here's the datasheet, but nothing is obvious as to the latch current, well obvious to me anyway, as it's still a little cryptic to my untrained eye.
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00041395.pdf

 

[Arouse1973]

Look at Fig 6 graph on the data sheet maybe there you will find some useful information.
Thanks
Adam

 

[NMNeil]

Thanks.
I was looking for something along the lines of a minimum and maximum value rather than a calculated value.
Still have a lot to learn.