Just putting some feelers out there to see if anyone has used these before. I am planning a very simple amp, with minimal board components, and only 2 output devices. These are rated at 500W each, so using one per rail should leave me with a board that will deliver 450W from 70-0-70dc. Any thoughts?
I have used the BUZ901 before in a power amp and got good results.
Be careful how you work out power dissipation.
40% of power is lost in the heatsink in class AB.
However, each MOSFET is only on for half the time.
You lose a bit of dissipation due to cross conduction to eliminate crossover distortion.
Be careful how you work out power dissipation.
40% of power is lost in the heatsink in class AB.
However, each MOSFET is only on for half the time.
You lose a bit of dissipation due to cross conduction to eliminate crossover distortion.
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Hey Nigel
Yes I am aware of that. I usually allow for 50%, thus having plenty room for SOA. These mosfets however are rate at 500W per device. Its package looks like bridge rectifier, and it has 4 tabs. This is why having one P and one N device, I reckon should be safe for 500W RMS Total....?
Also check out BUZ905x4s. Similar setup. If you google it, it should bring up the PDF.
The board, excluding output devices, measures 20mm x 50mm - with no drilled holes! Perfect for DIY!
Should have some pics up later on today...
Yes I am aware of that. I usually allow for 50%, thus having plenty room for SOA. These mosfets however are rate at 500W per device. Its package looks like bridge rectifier, and it has 4 tabs. This is why having one P and one N device, I reckon should be safe for 500W RMS Total....?
Also check out BUZ905x4s. Similar setup. If you google it, it should bring up the PDF.
The board, excluding output devices, measures 20mm x 50mm - with no drilled holes! Perfect for DIY!
Should have some pics up later on today...
I will post the circuit and board asap. Just finishing off some details.
The link to the Mosfets is :
BUZ905X4S pdf, BUZ905X4S description, BUZ905X4S datasheets, BUZ905X4S view ::: ALLDATASHEET :::
I thought that thay were expensive, but if you work it all out, at the end of the day, I think they are worth it. I can get then for AU$28 each. If you take into account that the 125W version is around AU$6, multiply that by 4, and remember all of the gate and drain resistors you don't need anymore, as well as all of the soldering and drilling and board size!
I think we may be onto something, but I am looking for feedback about them - so far, it sounds really good!
The link to the Mosfets is :
BUZ905X4S pdf, BUZ905X4S description, BUZ905X4S datasheets, BUZ905X4S view ::: ALLDATASHEET :::
I thought that thay were expensive, but if you work it all out, at the end of the day, I think they are worth it. I can get then for AU$28 each. If you take into account that the 125W version is around AU$6, multiply that by 4, and remember all of the gate and drain resistors you don't need anymore, as well as all of the soldering and drilling and board size!
I think we may be onto something, but I am looking for feedback about them - so far, it sounds really good!
Those are based on Hitachi die. The Rds on over temperature is about 1R7 per die (1R0 at room temp), or 0R425 for four. 450W/4R requires 15A peak, or a 6.375V loss. The gate drive is about 1V per amp, so add another 3.75V, or ±64V gate drive (over temperature) for 450W/4R.
I hope your ±70V DC is regulated.
Ever wonder why a Hafler DH500 used an unregulated ±93V supply?
I hope your ±70V DC is regulated.
Ever wonder why a Hafler DH500 used an unregulated ±93V supply?
Not to be too much of a buzz kill (sorry...) but take a close look at the thermals. The die to case thermal resistance on the data sheet is almost 50% higher than that of four typical TO-3P devices (where thermal resistances act like resistors in parallel), so you'll run a bit hotter. Success depends on how hard you are pushing it.
The higher the bias the more I'd tend towards separate parts. Just guessing, but on a heat sink with a nice thick base to spread the heat from a concentrated source the BUZ905X4S should do well in moderately biased AB operation.
BTW, where can you buy them?
I didn't dig out the 901 datasheet, I used the IRFP240 as a reference @ .83C/W. That's not as big a delta single to quad, but still something to consider.
If the mounting surface is electrically isolated then you are actually ahead of singles with their required isolators' thermal resistance. The data sheet does not show a connection.
If the mounting surface is electrically isolated then you are actually ahead of singles with their required isolators' thermal resistance. The data sheet does not show a connection.
Yes I saw that it makes no reference to any pins being connected to case, so it will be interesting to see.
Well now. I ordered a pair from RS, and they pitched up yesterday, but they sent me the 901's and 906's instead of the x4s varient. A little bit upset because I waited so long, and I specifically underlined the x4s part in the email to them...... Anyways - you can't win them all.
I have sent a mail to magnatec and have asked them directly about them, so as soon as I get an answer, I will post here.
In the meantime, lets assume that they will work, but at the same time trying to prove that they won't. We can then weigh up the odds when the price arrives.....
Keep the comments coming...
Well now. I ordered a pair from RS, and they pitched up yesterday, but they sent me the 901's and 906's instead of the x4s varient. A little bit upset because I waited so long, and I specifically underlined the x4s part in the email to them...... Anyways - you can't win them all.
I have sent a mail to magnatec and have asked them directly about them, so as soon as I get an answer, I will post here.
In the meantime, lets assume that they will work, but at the same time trying to prove that they won't. We can then weigh up the odds when the price arrives.....
Keep the comments coming...
The BUZ 900 160V and 901 200V fets are the same die, the 200V parts are selected. If you are going to use a single pair, the BUZ900X4S 160V part will be adequate.
The 140V voltage you have chosen is quite conservative. Unless you are going to use a very high current supply and a low impedance load I would think you could easily increase this to 150V (75 - 0 - 75).
The best thermal performance with the Semefab mosfets is acheived with the single die T03 steel package, preferably mounted on a heatsink without any insulators. The heatsink then has to be isolated as it is at output potential.
If the SOT 227 package is electrically isolated then this could be quite a useful part. It is still going to need a fair sized heatsink though.
The gate capacitance is likey to be quite high, so best not driven directly by the VAS.
These packages have been listed as under development for years, If you can actually source these parts please keep us posted with your progress.
The 140V voltage you have chosen is quite conservative. Unless you are going to use a very high current supply and a low impedance load I would think you could easily increase this to 150V (75 - 0 - 75).
The best thermal performance with the Semefab mosfets is acheived with the single die T03 steel package, preferably mounted on a heatsink without any insulators. The heatsink then has to be isolated as it is at output potential.
If the SOT 227 package is electrically isolated then this could be quite a useful part. It is still going to need a fair sized heatsink though.
The gate capacitance is likey to be quite high, so best not driven directly by the VAS.
These packages have been listed as under development for years, If you can actually source these parts please keep us posted with your progress.
@ XOC1
I was going to use the 200V version, as I would like to increase it to 84-0-84dc eventully. I would increase the count to 2 devices per rail in this case, but initially I would run 70-0-70 for some R&D.
I was thinking of driving them with mje340/350's, with a fairly high bias. I am a fan of doing this any way.
I agree about the thick alloy to dispearse heat. This call for some engineering. I reckon a 10mm piece then bolted onto the heatsink should do.
What does anyone think about gate resistors? 68r 1/2watt??? Just thinking about the current at HF seeing as the diagram shows that all 4 gates are tied...
I was going to use the 200V version, as I would like to increase it to 84-0-84dc eventully. I would increase the count to 2 devices per rail in this case, but initially I would run 70-0-70 for some R&D.
I was thinking of driving them with mje340/350's, with a fairly high bias. I am a fan of doing this any way.
I agree about the thick alloy to dispearse heat. This call for some engineering. I reckon a 10mm piece then bolted onto the heatsink should do.
What does anyone think about gate resistors? 68r 1/2watt??? Just thinking about the current at HF seeing as the diagram shows that all 4 gates are tied...
I would think that you will need a higher resistance than that. Check out this thread on the dual die parts. Post 21
http://www.diyaudio.com/forums/solid-state/114953-vbias-semelab-double-die-lmosfet-3.html
The real fun will probably involve stopping this amplifier from oscillating.
Be sure to check it out with a fast scope! You may want to investigate local decoupling caps for the Mosfets, using different values for the N and P gate resistors, and / or capacitance added to the N channel gate.
http://www.diyaudio.com/forums/solid-state/114953-vbias-semelab-double-die-lmosfet-3.html
The real fun will probably involve stopping this amplifier from oscillating.
Be sure to check it out with a fast scope! You may want to investigate local decoupling caps for the Mosfets, using different values for the N and P gate resistors, and / or capacitance added to the N channel gate.
@XOC1
Thanks for the thread. Had a brief look through, and it seems a bit of a redisign is i9n order...
I am trying to keep the board as simple as possible with the smallest component count. Obviously keeping sound quality and safety.
I have worked around the generic mosfet amp design, and tested on a pair of k1058 and j162's just to get the board layout and circuit working properly. I am aware that the BUZ's will be very different, but we will cross that bridge when we get the devices!
Everyone happy with driving them with 340/350's ??? 2n5401/2n5551 on diff and vas???
Thanks for the thread. Had a brief look through, and it seems a bit of a redisign is i9n order...
I am trying to keep the board as simple as possible with the smallest component count. Obviously keeping sound quality and safety.
I have worked around the generic mosfet amp design, and tested on a pair of k1058 and j162's just to get the board layout and circuit working properly. I am aware that the BUZ's will be very different, but we will cross that bridge when we get the devices!
Everyone happy with driving them with 340/350's ??? 2n5401/2n5551 on diff and vas???
Hi Coastben
I think you will find that these devices have never been released.
Between 2005-7 I worked very close with a UK company that had ties with Semefab and Semelab the distributors of the BUZ lateral mosfets.
I even went to Semefab in Scotland and spent two days with the then CEO of Semefab, Allan James. So I know quite a lot about these devices.
The only ones they ended up releasing in any qty was the dual die variants.
And with these they had enormous amount of problems with them.
They have since taken them off the market.
I spent over two years developing commercial amplifiers using these devices.
My advise would be to stick to the Renasas/ Hitachi Laterals, they are much easier to work with and IMHO are a much better device.
Cheers
Anthony
Hi Anthony
Well that clears up a lot of questions we were about to start asking - thanks for the info...
If I recall correctly I think I spoke to you n the phone about 2 years ago in regards to them. My memory could be fading though...
I will continue with the board and circuit, and apply different outputs. Keep it simple! I am trying to get as much useable power out of as few devices as possible - less soldering, less part count etc - A fairly "bang it together" kind of amp. Aiming for around 500W into 4R or so. I might change over to mjl21193/94's, or 5200/1943's... They are fairly affordable in Qty.
Well that clears up a lot of questions we were about to start asking - thanks for the info...
If I recall correctly I think I spoke to you n the phone about 2 years ago in regards to them. My memory could be fading though...
I will continue with the board and circuit, and apply different outputs. Keep it simple! I am trying to get as much useable power out of as few devices as possible - less soldering, less part count etc - A fairly "bang it together" kind of amp. Aiming for around 500W into 4R or so. I might change over to mjl21193/94's, or 5200/1943's... They are fairly affordable in Qty.
If you want the most bang for buck I would use the mj21193/94s or what I use in all of my current amplifier modules is the Toshiba 2sk1530 2sj201 devices. the latter which are most excellent and very powerful and rugged.
and no oscillation issues at all at any power level. for 500 watts you will need 4 pairs of the toshiba devices, the bipolar devices are likely to require at least another extra pair.
The latter devices will depend on who you talk too as far a ruggness, for my money and experience you cannot go past the toshiba mosfets.
They are very easy to work with and very fast. My amps are able to produce very clean sinewaves at 500khz -3db using these devices and not cross conduction issues at all...
Cheers
Anthony
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