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Forum Index : Electronics : Can members here please check my MOSFET choice?

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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9305
Posted: 05:47am 12 Sep 2024
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OLD MOSFET - F35W60C3: (can get these anymore, and F47W60C3 lead-time is going to be ages)
f35w60c3.pdf

NEW MOSFET I WANT TO USE:
STP45N60DM6 MOSFET in TO-247 package.pdf

Can the members please look at these two, and tell me if I am on the right track?
The vital stats look about right - case style, pinout, voltage and current rating, Rds-ON resistance.....
Smoke makes things work. When the smoke gets out, it stops!
 
wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 1156
Posted: 06:12am 12 Sep 2024
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I would confidently fit one as a replacement. The replacements turn on and off times are impressive. The new part quotes the internal diode parameters - couldn't see anything on the original parts data sheet except for forward voltage which is fine. The gate voltage of the original is quoted as +/- 35V (new part +/- 25). Cant believe anyone in their right mind would be using more than +/-15 anyway.  Your warranty with my observations is over when you have finished reading them.....  good luck!  - if there are any "gotchas" with the replacement I would have fallen for them too.
Edited 2024-09-12 16:14 by wiseguy
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9305
Posted: 06:42am 12 Sep 2024
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Excellent, thanks very much for your comment.  
I will order some.

The only "Replacements" for the original part, are listings all over ebay and AliExpress for them, but I fully expect those to be fakes or at best 2nd-hand ones taken out of boards, so they could have already had a stressful life.

The ST part, I can get from element-14, so I know they will be the genuine article.  
Smoke makes things work. When the smoke gets out, it stops!
 
Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9305
Posted: 01:47am 19 Sep 2024
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New parts arrived - legs are shorter then the original, so won't fit!  





I never noticed that in the datasheet....  

However, I have cut the legs off the old MOSFETS, and sweat-soldered them on to the legs of the new parts(after trimming them a little), so that the legs are now long enough to poke through the PCB and can be soldered.  I THINK that will work OK.  Full anti-static precautions used during this mod, and also during the install back in the PCB.





The only thing that worries me A LITTLE, is if the legs of the transistor heat up enough to melt the solder and it dribbles off, but I DON'T THINK that will happen, cos the new devices are rated to 160'C, but even that is not hot enough to melt solder, so I THINK I'll be OK.....
Edited 2024-09-19 11:50 by Grogster
Smoke makes things work. When the smoke gets out, it stops!
 
phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2134
Posted: 03:00am 19 Sep 2024
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  Quote  if the legs of the transistor heat up enough to melt the solder and it dribbles off

That is a good thing! They can only get that hot after they have died.
 
Grogster

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Location: New Zealand
Posts: 9305
Posted: 04:24am 19 Sep 2024
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Put it all back together, switched on tentatively, and three seconds later, one of the new MOSFETS exploded!  

I've spent too much time on this bloody thing as it is, and I am trying to work out how to move house, so I am just gonna send it back and say I can't fix it.

You can't win them all!  
Smoke makes things work. When the smoke gets out, it stops!
 
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