UcD like topology amp.

[Whortless]

Hi Luka and others,

Here the rapidshare video link of my amp. RapidShare: 1-CLICK Web hosting - Easy Filehosting
I decrased the sw frequency to 440kHz to ensure safe operation. I think it is time to play with DT resistors. My camera is not so professional so the sound quality seems a bit decrased with my record. Only the midranges are better. But you can guess the bass and treble.

Regards

NB. Last night I adjusted the dead time to 35ns and saw a SW frequency of 750kHz which is too close the upper operating frequency limit of IRS20954S. Therefore to play with dead time I decrased the frequency by increasing the 1K to 2K2 on the FB circuit. Now the spikes on the speaker output are decreased down.

 

[Whortless]

Here another video of the amp; RapidShare: 1-CLICK Web hosting - Easy Filehosting . I hope this is more audible.

Regards

 

[luka]

looks very good, thanks for this, I uploaded it to youtube in order to watch it, you record it with Nokia?

 

[Whortless]

Hi, Luka thanks for your upload it doesn't matter . I recorded the vid. with may cell phone ( samsung,SGH-i450. It uses Nokia software ) and then my old camera KODAK C330 (quick time *.mov format). Last night I sync. the amp to 400kHz with ceramic resonator osc with the aid of 74HC14. It is pretty well synch to that frequency and really stable. The other module that shown in the video is my other UCD application with MAX5048. It is stable also and works at 400-450k without sync. I again fixed the Fsw to 400k by sync. It is necessary to prevent Ps. pumping effect, crosstalk ect. if your are running multiple modules.

Anyways, the UCD amps that I created seems stable and cool working while providing good sound quality. They are suffering from many accidental errors ( short circuit on somewhere). Therefore the concept is very usefull for newbeis and DIYers.

Regards

 

[luka]

Thanks for the vids, watched them today again

Cool board with 6 channels on, that would make really small home amp for movies
waveforms are great, 400khz is where you wanna be, at least some where close to this

Sound must be really good
So what's next to do?

 

[Whortless]

The IRS20954S was for only fun purpose . But, I might to think replace my UCD car amp(remember my old fully discrete application) with these. I created the 6 CH module( hybrid shown in vid.) for my hometheatre system. It is waiting me to create and complete the house keeping PS' and SMPS(600-700W powerfactor corrected AC-DC). All the amps has its own disable and OC protection circuits which must be connected to the system controller. Also the output DC protection circuits has to be added. I am also intend to use pushbutton interface audio processor like MAX5406 for kareoke applications of my daughter .

This last module will go to my cousin, who is an electronic engineer, to show him the ability of a Chemist in electronics .

Regards

 

[Whortless]

What is youtube search keyword?

looks very good, thanks for this, I uploaded it to youtube in order to watch it, you record it with Nokia?

Luka, what is youtube search keyword for my vid. I used the original names and did not get result .

 

[luka]

oh I set it on privet, me only, unless you allow me, so everybody can see it, then I can change this + post link

 

[Whortless]

Luka,

It does not matter. You can upload it as public vid. You do not need to give my name or nick. Upload it as yours .

 

[luka]

You already know my name

Here is the link

 

[acid_k2]

Whortless, really nice work.
Now I'll try to obtain the IRS20954 from my local electronics shop... hard job

 

[Whortless]

Good luck

Hi,
Thanks and good luck. Will you use compementary output comparators like mine?(LT1016,LM361,TL3016 LT1116, MAX913,MXL1016 etc.). Please use good mosfets like IRF540Z, IRFB5615,5620 and similar like these. I also advise you to use add passive poles into your amp. If it would not better philips won't use the circuit in their home appliance( FM730). I enclosed shematic for non SWCAD users.

Regards

 

[Cro maniac]

Nice design Whortless !

Do you have some measurements of THD of your amp ? That 2nd passive pole looks interesting ,every UcD paper I had read mentions it but I never saw one diyer implementing it. I wonder how much can one expect the THD to decrease when adding the second pole to the FB.
At the moment I'm in a process of designing a half bridge amp with irs20957 and that's how I bumped to this wonderful thread.
I see that you have set overcurrent limit very high. Was there a problem with false triggering of ocp ? For low side it is set at 50A and for high side 38A if I calculated it correctly, and I see from the datasheet that those Philips mosfets can "only" take max 22A @25°C.
Are you using balanced input to your amp ? The feedback configuration suggests you are, otherwise, I think it could be made simpler if using only single ended input.
Do you have emi problems ? I see the toroid is mounted vertically and you have the connections on both sides of the PCB.
The board looks very well made. My boards containing smd elements usually don't look nearly half as good as yours . Nice work !

 

[Whortless]

Nice design Whortless !

Many thanks! And sorry for the delayed answer.

Do you have some measurements of THD of your amp ? That 2nd passive pole looks interesting ,every UcD paper I had read mentions it but I never saw one diyer implementing it. I wonder how much can one expect the THD to decrease when adding the second pole to the FB.

Un fortunately I do not have chance to measure distorsion values yet. But, one of my friend really like its tonal quality.

At the moment I'm in a process of designing a half bridge amp with irs20957 and that's how I bumped to this wonderful thread.
I see that you have set overcurrent limit very high. Was there a problem with false triggering of ocp ? For low side it is set at 50A and for high side 38A if I calculated it correctly, and I see from the datasheet that those Philips mosfets can "only" take max 22A @25°C.

I set OCP limits high for test purpose because my PS has OCP protection. Also the mosfets that I have used has 35S forward transconductance so, they can suffer from some short circuit or inproper timing events for a while. But, I would really suggest to use IRS20957 instead of 20954 for this purpose because 20954 has not matched internal protection circuits.

Are you using balanced input to your amp ? The feedback configuration suggests you are, otherwise, I think it could be made simpler if using only single ended input.

I did not decide the balanced or unbalanced input yet. But this desing can let both application. If you are asking about not using the 2nd pole components on unused input. I can say I did not test that configuration. But, this can make some offset on output.

Do you have emi problems ? I see the toroid is mounted vertically and you have the connections on both sides of the PCB.
The board looks very well made. My boards containing smd elements usually don't look nearly half as good as yours . Nice work !

I do not have EMI problem, my FM radio can drive the amp (single ended) and also can work near to amp while the amp driven by computer. But, if I connect the ground pin of my scope to center of output mosfets to measure the high side gate timig my LAB PS's LCD shows some silly values . I think it is normal because the probe cable became a very good antenna for the amp. The output filter do not have connetction on both side. It has connections only on component side of PCB. I do not have much experience of desining a good PCB and I usually do not consider some "musts" while drawing it. But, at the end I usually like my desings and up to now i did not faced some interference problems or something like this. Futhermore, I desinged a bit complicated version of the amp and I think you do not want to see it.

Best regards and good luck on your desing.

 

[Bender.ru]

Hi Whortless! Nice project, my congratulations .

 

[Whortless]

Thanks

Hi Whortless! Nice project, my congratulations .

Dear Bender,

Please excuse me because of posting some improvements in your thread like mine. I think you can try passive pole version and can post the distorsion measurements for DIYers. I do not have much time to do these issiues and also have to barrow some instruments from my friends. Anyways, again many thanks and my congratulations about the idea.

Best Regards

 

[savu]

Dear Bender and all,

I realised that Bender and the others are not interested with the above questions. Anyway! Therefore I tried to make my own desing and get the smallest amp below. Bender, please excuse me if I get you bother by posting in your thread.

First of all simulate the shematic. I used the chip IRS20954S which is known as unsable( Make a diyaudio search) and old IC. I get it from Farnell, it is cheap for now. I did not faced a problem by implementing it. My output mosfets are IRFB5615PBF. SW frequency is 550-600kHz. Input comparator is MXL1016 from Maxim and sound is very good just for my firts testing. DT adj is max(45ns) for first test purpose. I think I have to decrase the sw frequency down to 400k and set the dead time into a suitible time(25ns?).

Regards

NB. If someone interested I can give the PCB toner file

Hello Worthless ...
I am a bit curious about the pcb ... looks very tight.
I am triyng to make my own pcb's but have problems with understanding the layout for class D because i'm new in class D. But i will learn a lot from youre schematic and PCB.

Thanks a million.

Savu Silviu

 

[MOER]

Irs20955

I have many in stock. Price is $3.25 + shipping.

 

[savu]

I have many in stock. Price is $3.25 + shipping.

I live in Romania and shippment is 50$, and I want to make my own PCB because I want to learn.
I just wanted to look at the design to see the gate traces, the ground planes and so on ...

Best regards,

Savu Silviu

 

[savu]

First of all simulate the shematic.

Hello Wortless,
Do you have the LTSpice model for IRS2095?

Best regards,
Savu Silviu