Author Topic: Successful TPU-ECD replication ! (Read 1147513 times)

ronotte · « **Reply #840 on:** July 16, 2007, 11:52:56 AM »

@Darren,

the pin numbers on my diagram are correct. You can check-it on IR 7307 Application attached. Of course remember that you can drive the 7307 with +12V without any problems (on past I used only the +6V for safety purposes...but it doesn't need).

Best luck for your work!

@GK,

thanks for assembling my speech! ...are you ready for firing your Mobius?

ronotte · « **Reply #841 on:** July 16, 2007, 11:58:29 AM »

...sorry here's the attachement

z_p_e · « **Reply #842 on:** July 16, 2007, 02:59:59 PM »

Quote from: ronotte on July 16, 2007, 11:52:56 AM

@Darren,

the pin numbers on my diagram are correct. You can check-it on IR 7307 Application attached. Of course remember that you can drive the 7307 with +12V without any problems (on past I used only the +6V for safety purposes...but it doesn't need).

Best luck for your work!

@GK,

thanks for assembling my speech! ...are you ready for firing your Mobius?

Roberto,

Thanks for the app note.

I see the problem now....the error is in their application note.

They have the N-channel and P-channel devices connected opposite. The P-channel needs to be at +V, and the N-channel at gnd.

I'll email IR and let them know.

Thanks,
Darren

giantkiller · « **Reply #843 on:** July 16, 2007, 05:45:29 PM »

Quote from: ronotte on July 16, 2007, 11:52:56 AM

@Darren,

the pin numbers on my diagram are correct. You can check-it on IR 7307 Application attached. Of course remember that you can drive the 7307 with +12V without any problems (on past I used only the +6V for safety purposes...but it doesn't need).

Best luck for your work!

@GK,

thanks for assembling my speech! ...are you ready for firing your Mobius?

I have TC4427's on the way. They are faster fet drivers.

--giantkiller.

nong · « **Reply #844 on:** July 16, 2007, 07:24:59 PM »

This is for high speed mosfet here.

z_p_e · « **Reply #845 on:** July 17, 2007, 01:03:35 AM »

Thank you nong for that very good writeup

Ok, Roberto, I've done a little more studying of that circuit connection.

It is not an error per se, but it is somewhat unconventional to configure the driver that way. What IR has done is configured the MOSFETs in a Source-Follower topology.

This is good for a low impedance drive, but has other disadvantages. There is a minimum 3.5V loss in the drive voltage due to the Vgs threshold, which explains why there were problems driving the Power MOSFET fully ON and OFF with only a 6V supply. Also, there is a rather large "gap" in the switching, which amounts to a "break-before-make" switch sequence.

At any rate, it will work if sufficient voltage drive is implemented, but it still is unconventional in the sense that Driver chips using complementary MOSFETs on the output, do not do this. They use an inverter topology. I would encourage you to try a "purpose-designed" MOSFET driver to see if there are any differences/improvements.

I'm using the MAX4420 as a driver chip. There are many good ones to choose from. No sense in redesigning the wheel

Regards,
Darren

giantkiller · « **Reply #846 on:** July 17, 2007, 03:04:13 AM »

Quote from: z_p_e on July 17, 2007, 01:03:35 AM

Thank you nong for that very good writeup

Ok, Roberto, I've done a little more studying of that circuit connection.

It is not an error per se, but it is somewhat unconventional to configure the driver that way. What IR has done is configured the MOSFETs in a Source-Follower topology.

This is good for a low impedance drive, but has other disadvantages. There is a minimum 3.5V loss in the drive voltage due to the Vgs threshold, which explains why there were problems driving the Power MOSFET fully ON and OFF with only a 6V supply. Also, there is a rather large "gap" in the switching, which amounts to a "break-before-make" switch sequence.

At any rate, it will work if sufficient voltage drive is implemented, but it still is unconventional in the sense that Driver chips using complementary MOSFETs on the output, do not do this. They use an inverter topology. I would encourage you to try a "purpose-designed" MOSFET driver to see if there are any differences/improvements.

I'm using the MAX4420 as a driver chip. There are many good ones to choose from. No sense in redesigning the wheel

Regards,
Darren

Review: http://datasheets.maxim-ic.com/en/ds/MAX4420-MXT429.pdf
on page 5. They comment about vil and vih. The input must not be allowed to stay between vil and vih for more than .5us. One interesting note is that ringing may be problem.

Saw that and it piqued my alarms.

--giantkiller. Ya just never know the rules being outside the boundaries.

ronotte · « **Reply #847 on:** July 17, 2007, 09:31:39 AM »

YES Darren,

you are right! I did not noticed that in fact it is a sort of double source follower.....of course it does show the potential problem you correctly said.... but on the positive side there is the 'very low output impedance' which is mandatory if you want charge correctly and full the Power Mosfet Gate capacitance + Miller effect capacitance. Said fact is necessary to put the Mosfet in avalache state that is our target. Sorry about my typo on +6V: THE IR7307 MUST BE SUPPLIED WITH +12V.
In the past I spent lot of time trying to drive the Power Mosfet in every possible way -> always experienced big problems readily shown by my high bandwidth scope! The IR solution was the first to meet the full IRFP460 specifications, but of course the Micrel MIC4426/4427 are also a very good and easier alternative as well as other providing that are able to show less than 3 Ohm driving impedance to power mosfet gate! (GK : sorry I did not try the MAX4420 chip..so I can't say anything).

Regards to all from

Roberto

z_p_e · « **Reply #848 on:** July 17, 2007, 02:36:06 PM »

Roberto/GK,

The MAX4427 is an upgrade to the TC4427.

The MAX4420 is the "single" version of the MAX4427, but has double the drive capacity.

Darren

giantkiller · « **Reply #849 on:** July 17, 2007, 10:34:04 PM »

Thanks Darren,

Maxim-ic has a very liberal samples policy also.

--giantkiller.

otto · « **Reply #850 on:** July 18, 2007, 07:49:36 AM »

Hello all,

what to say??

In short:

I made a magnetic amplifier, pulsed it and now again, I have nothing anymore. Everything burned. A lot of smoke and power supply and oscillators are damaged. Totally. Scope, OK, because it was NOT connected.

As Im on vacation from next Monday so please, dont sent me PMs and mails because I cant answer.

For at least I month Im out of "Game".

I wish and I KNOW that the people here can built a good TPU in this month.

Good luck to you all, be very carefull.

Otto

Bruce_TPU · « **Reply #851 on:** July 18, 2007, 09:32:53 AM »

Hello Otto,

I am very sorry to hear about your loss of your oscillators, controller and power supply. I can imagine how frustrating that can be. Hang in there!

Warm regards and peace,
Bruce

Earl · « **Reply #852 on:** July 18, 2007, 09:36:39 AM »

Otto,

so sorry to hear this.

May I suggest to all experimenters to only use batteries for testing and NEVER use
regulated power supplies.

Earl

Quote from: otto on July 18, 2007, 07:49:36 AM

Hello all,

what to say??

In short:

I made a magnetic amplifier, pulsed it and now again, I have nothing anymore. Everything burned. A lot of smoke and power supply and oscillators are damaged. Totally. Scope, OK, because it was NOT connected.

As Im on vacation from next Monday so please, dont sent me PMs and mails because I cant answer.

For at least I month Im out of "Game".

I wish and I KNOW that the people here can built a good TPU in this month.

Good luck to you all, be very carefull.

Otto

ronotte · « **Reply #853 on:** July 18, 2007, 10:24:08 AM »

Hello Otto,

what happened exactly? We all are anxious to help you if possible!!

P.S. and oscillators are not a big problem.

Roberto

otto · « **Reply #854 on:** July 18, 2007, 11:37:30 AM »

Hello all,

yesterday I tried to make a magnetic amplifier like in the picture showed yesterday. A little bias voltage.....2 contra connected coils like in the picture.....and thats it. In 1 moment rised the amperage from the power supply to an value that I even cant imagine.

Now you will say a short. Yes, but this is impossible. ALL my wires are very good isolated....

I really dont know what happened. I only pulsed the coils, changed the frequencies...

OK. Now I finally have the chance to build good oscillators.

@Roberto,

are your oscillators OK??
I have the 4427 ICs, not using them....I think I will build my oscillators like you have done it.

Otto

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