Stereo Class-D amp HIP4081

[Whortless]

Hi to every body,

I started to desing a class-D amp(enclosed shematic). I would likte to make it stereo for full range at least 100W/4ohms. I used modified self oscillating iraud amp1. Also I choose HIP4081 instead of IR2110/2113. As I showed in the shematic, now I am using IRFP250 as output mosfets. I know they are slow, has high Qg and other worse parameters but they are working in my bread bord without heating. I am now using only one channel oscillating about 220KHz. I also tested IR2113 with same shematic but output mosfets warm up. Again I tested IR2113 with IRF540(ST) and saw high side ise still warming up. Therefore I think my last desing is ok for only 12V. For final desing, I think I need level shift and symetrical PS for input opamp and output mosfets. Now all of them running on the supply voltage of mosfet driver.

I need some help on calculating closed loop gain of this desing.

Any suggestions will help much from you experienced DIY'ers.

Regards

[Whortless]

Are not there someone to give me some idea?

[luka]

Hi

I can't help you with loop gain, but I have a question.

I also tested IR2113 with same shematic but output mosfets warm up. Again I tested IR2113 with IRF540(ST) and saw high side ise still warming up.

What was your capacitance for upper, HI side drive?

[Whortless]

Hi Luka,

If you are asking about C8 it is 680nf. But tried 220nf and get it working without heat of high side mosfet and UVL protection of HIP4081. And now I am using 100nf+1uf(electorlitic). No problem with HIP4081 there is no heat on both mosfet. I also replaced R105 4.7K to 1K and now oscillating frequency is 330KHz and better sound.

Regards

[luka]

Hi

You used 680nf with IR? That is too small. Use 22uF or more, when you will go in hard clipping you will need it. I use 100uF elco and 22uF tantal in parallel, with no heating in upper mosfet

[Whortless]

OK
I will take this suggestion to care. But IR2113 failed in my most desings. I did some SMPS circuits with 2113 also one of my friend, who has a scop(oscilloscope), did a fulbridge SMPS with IR2113. We saw there with scop the H side mosfet is not turned off properly although there is a dead time on input stage of 2113. Therefore I used HIP4081 because, it has delay time adjusment for H and L side. You can have a look to data sheet and also application note of HIP4081 on www.intersil.com . The delay resistors with 30K there is a dealay lets say about 30-40ns or so.

Kind regards

[luka]

Hi

Could you post or send me schema of that smps or amp (if you did it with IR), I'll take a look of what you used.
I have both smps and ClassD amp running with IR and that is with no problems. Didn't destroyed not even one IR.

Hip are great but limited by max voltage. If you will be making one with HIP you should look here first.

But you made this one
Didn't it work? From that picture I made my, which look pritty much the same

[Whortless]

Hi luka,

As I saw you know what I did before. OK the scop photo belong to driver transformer version of my SMPS. But, both of them still working. The problem is IR version of my SMPS heating a bit up. Also scop result of IR version like a sinus. I enclosed the shematic of my smps' IR version. And also many thanks to you for the HIP link.

[Whortless]

My final desing enclosed. The input section of CH-B is same with CH-A. I put there a level translator but, i think i should put a reverse polarity 1N4148 to B-E legs of Q105. +/-Vss is about 35 to 38V so the final total power supply 70 to 76V.

Ps: My circuit is not a full bridge. But ,stereo signals will be 180 degree phase angle with additional input buffers. That will give me the chance of briging two channells.

[luka]

Hi

I can tell you right now that 0.47uF is not enough, use much high C and I would use irfp450 reather then 460,rest will check later.