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Class D Switching Power Amplifiers and Power D/A conversion

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Old 7th May 2011, 09:16 AM   #11
Pafi is offline Pafi  Hungary
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Quote:
Originally Posted by jeppson View Post
Hi, sorry I've not been able to reply to this thread. Yes R5 and R6 are there only for simulation, since pspice doesn't have the right component. Regarding the picture of the oscilloscope, I forgot to add that we only used +/-5V for that picture.
I saw it was +/-5 V, but which voltage was it, and what was the other supply voltages? On your picture there are 5 batteries! What is their voltages in reality (if you changed them during different tests, then you should mention the variations too!), and how really implemented them?

Quote:
So what I want to know is how I'm gonna get 0 to (-15)V after the optocoupler, I've read that a schmitt trigger can be used but I can't get that to work.
Schmitt trigger means only that it has hysteresis. It's a nonimportant feature here. What is important is simply the input and output voltage. There are many ways. The simplest discrete amplifier is common emitter configuration. You can see it in the UCD schematic for example. Or you can use a dedicated gate driver IC, or an NE555, etc...

But I suggest you to forget that "0 to (-15)V" specification! Gate voltage should be referenced to source voltage, not to GND! Low side gate power supply should be "Vss+10V"!

Quote:
Should I look for an opto that has 15V output, or what do you think is the best way to go.
I think the best way is dedicated gate driver IC. UCC27200 up to 100V. For small power the best is integrated PWM amplifier IC.
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Old 7th May 2011, 11:49 AM   #12
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Pafi

What's your experience with UCC27200?
I mean all the things not included in the datasheet, like tolerance to transients, general robustness etc.
Have you compared it to some similar drivers like LM5101 or HIP2100?

Adam
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Old 7th May 2011, 12:49 PM   #13
Pafi is offline Pafi  Hungary
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Adam!

I used UCC27200 only twice. My experience is very good, but it has some speciality compared to for example IR2110. It is very fast, and input is not histeretic, this because you have to take attention to assure clean, fast input transition.

I incidentally applied 120 V to the amplifier, MOSFETs were FDP3652, and everything survived despite of 1...2 A current drawn for some seconds.

My biggest problem with it is the lack of shutdown pin.
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Old 7th May 2011, 05:12 PM   #14
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Thanks for information
One thing I like most about IR2110 is separate 'ground' connections for input and low side source return, the UCC lacks that.
Are you using a dedicated source return track or a plane?
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Old 7th May 2011, 08:40 PM   #15
Pafi is offline Pafi  Hungary
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Quote:
Originally Posted by darkfenriz View Post
...
Are you using a dedicated source return track or a plane?
I'm not sure what do you mean, but I don't use any special track.

(I attached the first version, but later I had to add some dead time.)
Attached Images
File Type: gif UCC27200.GIF (54.0 KB, 62 views)

Last edited by Pafi; 7th May 2011 at 08:43 PM.
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