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Class D Switching Power Amplifiers and Power D/A conversion

My 1st Class-D Amp -TPA3255 with PFFB
My 1st Class-D Amp -TPA3255 with PFFB
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Old 6th March 2017, 10:50 PM   #11
mantabernd is offline mantabernd  Germany
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Perfect thanks.
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Old 6th March 2017, 11:43 PM   #12
doctormord is offline doctormord  Germany
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Quote:
Originally Posted by mantabernd View Post
Nice work!
In my design this snubber dissipates a lot of power and sometimes even dies if amp
clips without load. I need to replace the R then... But I'm actually using 1.33uF + 3.3 Ohms so corner frequency is a bit lower in my design.
What do you expect, do a simulation and see for yourself. It's totally normal without any bw-limit on the inputs. With values from application note, the snubbers resonance frequency is at about 47kHz.

Been there, done that:

http://www.diyaudio.com/forums/class...ml#post4987732

30A current in the snubber.

Last edited by doctormord; 6th March 2017 at 11:46 PM.
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Old 13th March 2017, 03:20 AM   #13
JohnnyInBris is offline JohnnyInBris  Australia
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Originally Posted by mantabernd View Post
Perfect thanks.
With no load and with audio signal levels just below clipping there is no heating of the snubber resistors. I would suggest that there may be a HF instability in your design or that you are testing with unrealistic signal levels in the 10s of KHz region
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Old 13th March 2017, 06:27 AM   #14
mantabernd is offline mantabernd  Germany
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Quote:
Originally Posted by JohnnyInBris View Post
With no load and with audio signal levels just below clipping there is no heating of the snubber resistors. I would suggest that there may be a HF instability in your design or that you are testing with unrealistic signal levels in the 10s of KHz region
Thanks for checking this in your design.

It only happens when the amp clips. Shortly before clipping it's all ok.
And no, my test signal was 1kHz sinus.

But actually I could solve this problem already by compensating the post filter feedback loop. It's stable now even with no load.

My phase shift is now between 15 and 45.
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Old 6th October 2017, 01:57 AM   #15
JonesySA is offline JonesySA  Australia
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Have you used the SMPS much? Would you recommend it?
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Old 6th October 2017, 03:15 AM   #16
JohnnyInBris is offline JohnnyInBris  Australia
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I've used both linear and SMPS and I can't hear any difference except for fan noise in the SMPS
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Old 6th October 2017, 06:38 AM   #17
JonesySA is offline JonesySA  Australia
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Quote:
Originally Posted by JohnnyInBris View Post
I've used both linear and SMPS and I can't hear any difference except for fan noise in the SMPS
Could you link to the one you purchased? I'm interested in alternatives to the Meanwell which can be dearer in Australia.
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Old 6th October 2017, 07:25 AM   #18
JohnnyInBris is offline JohnnyInBris  Australia
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Originally Posted by JonesySA View Post
Could you link to the one you purchased? I'm interested in alternatives to the Meanwell which can be dearer in Australia.
free shipping 360W 48V 7.5A Switching Power Supply Driver for CCTV camera LED Strip AC 100 240V Input to DC 48V output-in Switching Power Supply from Home Improvement on Aliexpress.com | Alibaba Group
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