SSTC not getting interrupted

[Saattvik24]

I finished building a solid state tesla coil by using the schematics of Kaizer Power Electronics SSTC 1. Its working awesome except the enable pins of the UCC3732x are not working. I had bought them from Aliexpress. So the tesla coil always stays in continuous mode, even when I connect them to ground it still stays in continuous mode. I really wanted to use the musical interrupter. So is there anything i can do?

[coilinator]

If you study the datasheet from TI you will find a table that describes the output-state for a given input and also enable in.
so if enable is 0 - so grounded- our output has to be also 0. If they are not you may bouht some cheap crap 
Or maybe you swaped some pins ? To check your circuit it may help to just take the non inverting ucc out, put it on to an extra testbaord, give always high level on the input, and conect your interrupter as usual on enable. If you scope and see the same output as of the interrupter its fine, if just vcc coming out the enable pin is just a NC pin and your seller linked you...

[Mads Barnkob]

There is a logic table on page 14 here that shows you the combination of enable and IN to your OUT: http://www.ti.com/lit/ds/symlink/ucc27321.pdf

I have previously experienced that non-grounded / unused / floating input pins on ICs can make a SSTC run in continues mode, simply due to interference from the magnetic field of the secondary coil.

[Saattvik24]

I tested the IC separately by connecting the input to Vcc and enable to interrupter and still the scope shows that the output always stays high. So i guess i just purchased crappy IC's, they're from china after all. But aliexpress was the only source where I was able to find these IC's, couldn't find them anywhere else. So I'll just have to stick with a continuous mode tesla coil . If I find a new circuit or create my own that doesn't require them that would be nice. I was considering using the gate drive circuit of the SSTC built by loneoceans which involves a UCC27425 which has both inverting and non inverting outputs on the same IC. Too much changes shouldn't be required to make it work.

[Mads Barnkob]

It seems like they are getting discontinued, so it is also better to find alternative ICs that has the same/almost the same pinout and same specifications and adopt the UD designs to these.

Even digikey can only deliver at a 200 piece minimum order https://www.digikey.dk/product-detail/en/texas-instruments/UCC27321PG4/UCC27321PG4-ND/1911356

[dexter]

single chip double gate drive ic's work well
make sure they are inverting and non inverting
i successfully used MCP14E5 4A gate drivers from Microchip in both half and full IGBT's bridge SSTC's

[Saattvik24]

MCP14E5 is only available in smd package. Can you suggest me some suitable gate drive IC's in THT package? Can I use IR2184? It's maximum current output is only 1.8A so could that be a problem?

[Fumeaux]

MCP14E5 is only available in smd package.

It's not

Can you suggest me some suitable gate drive IC's in THT package?

There is a whole family. like the msp14e11. You have to search yourself. Look for something with

• Similar Vin
• Similar Current output
• Similar Rise/Fall times and turn on/off delay
• Similar "Typical Connection/Application" in the datasheet
• 2 channels in one chip (one inverted one not inverted) or you need two chips (one inverted one not inverted)
• Enable pins

The datasheet tells alot, like what gatecharge the chip can handle and you have to match it with your other components.

Can I use IR2184? It's maximum current output is only 1.8A so could that be a problem?

Probably not, but the chip has long delay times, which result in switching losses (which are bad)

[prabhatkumar]

 You could try this method. Use an AND gate after the interrupter and the signal from 74hc14 and then feed the output of the and gate in the signal pin of the ucc and leave the
Enable pin as it is or maybe tie it to supply volatge .