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Forum Index : Electronics : What TVS diode to bullet proof the EGS002
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| hary Regular Member  Joined: 15/04/2019 Location: FrancePosts: 89 |
Poida say to use these following TVS 15V diode to protect power mosfets gate drivers : RS part no. 815-2578 Vishay ICTE15-E3/54, Uni-Directional TVS Diode, 1500W, 2-Pin 1.5KE Do I absolutely need these or can I use any 15V TVS diode rated at 1.5kW ? Like these ones |
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poida Guru  Joined: 02/02/2017 Location: AustraliaPosts: 1419 |
Hary, I think it does not matter which TVS diodes you use as long as they are unipolar 15 or 18V. Sort of like a zener diode, but stronger and faster. You only need 4. Place them in a way to prevent voltages originating from the MOSFET gates traveling back to the IR2110 gate drive IC outputs. Locate them with the cathode (band) on the Gate and the anode on the Source. The aims are: - to allow any positive voltage into and out of the MOSFET Gate, up to about 15V to 18V. - to prevent voltages larger than that going into the Gate and into the gate drive output. - to prevent voltages less than -0.3V going into the gate drive output pins All voltages are measured with respect to the MOSFET Source. Certainly, plenty of people have found no need for these. I like to fit them, since they cost so little and the IR2110 specifications state clearly never to exceed certain voltages on the gate drive outputs. If you are unclear with the concept of voltages originating from the MOSFET gate, maybe have a look at this post I made earlier on the subject. wronger than a phone book full of wrong phone numbers |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Hi Poida. I mostly find some bidirectional. As we can find some uni-polar/unidirectional or bidirectional, I'd like to know if it matters to get the bidirectional instead ? From my understanding, it does't matter, they can be either uni or bi directional. But I'd like to be sure. |
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| poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1419 |
I would use unidirectional only. These will clamp negative voltages to approximately a diode drop, 0.3-0.5V This is what we want. Recall the IR specifications? They say never go less than -0.3V The bidirectional only clamp voltages above 18V to +18V and those less than -18V to -18V. Not good enough. We can't let voltages much more than -0.3V appear on the driver chip's output pins. Can you source some unidirectional TVS parts cheaply? If not, RS will, and they are cheap. When you cost a couple of hours on the workbench replacing MOSFETS against maybe $0.50 AU or $0.27 AU each in a pack of 20 you wonder how much time is worth.. wronger than a phone book full of wrong phone numbers |
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LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Looking at the 1.5KE15A/P6KE15A: At 1mA, Vbr variance is 14.3v - 15.8v At 70A, Vc_max is 21.2v I believe the major difference between the two series is that the P6KE series are rated for 600 watt operation while the 1.5KE series are rated for 1,500 watt operation From these specs, to me, the 1.5KE15A/P6KE15A looks like a fine TVS to put across GS? |
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| poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1419 |
My view is the two TVS devices you refer to would do the same job in the application of clamping dv/dt stuff. There is not a lot of current in this. 600W is about 599W too much for the task at hand. And so the 1500W is even more stupidly large for the job. I picked a device I could get in 5 days from RS, cost not a lot and a spec sheet I could read. I just want a fast acting version of a zener. I suspect you would make a better choice than I have and I'm fine with that. wronger than a phone book full of wrong phone numbers |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
So I've ordered 20 P6KE15A Thanks for the help. Should I also a set of 100 HY4008 ? Or any thing else for my little Chinese EGS002 board, bigger caps ? |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I don't know if you should get a hundred of them or not I do know that I've have read a lot about people saying they were very good mosfets for the price I also know that this stuff gets very addictive very quickly so do you think you could use that many mosfets that's the question you got to as be warned i am good parrot but Dumber than a box of rocks |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Well, the HY4008 are quite expensive to me, 1-2€/p, so almost as expensive as chocolate. I don't know if thei're addictive, but chocolate is for sure ! |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
if you plan on going by what some of the greats on here have already done then you probably won't blow very many up if you plan on deviating off what some of the greats already done you might want to get quite a few be warned i am good parrot but Dumber than a box of rocks |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Here in the United States a loaf of bread cost $2 you can get a dozen eggs for around the same so at a little over $1 a piece is quite cheap for mosfets here in the United States be warned i am good parrot but Dumber than a box of rocks |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
The option is always open for me to send you some and as long as shipping isn't over 10 or $15 then I will pay it also The greats have done the same for me the Great have earned their name in more than one way With time you're going to find out there's some really awesome people on this form be warned i am good parrot but Dumber than a box of rocks |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Ok BenandAmber, but don't worry, I know I can get a lot from people on this forum and the offer is very nice from you. But we must be realistic and paying 15USD shipping for 10 HY4008 is not worth it. I'd better pay the 15USD for the mosfet directly ordered from China. But be sure, I'll come to you later on.  |
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