best half bridge ic for high power SMPS - Page 1
Forum section: electronics / beginners

author: Herschel
author_rank: Regular Contributor
timestamp: December 31, 2024, 06:05:46 pm
content: So i have decided to make a 5.1 Home audio system which could output 1000watts. So for the the powersupply I decided to make a half bridge SMPS powersupply using sg3525. But the problem is, the IC creates high frequency switching noises at the output and seems to be pretty slow at feedback responding.Is it a good idea to go with TL494's ? I do have a led strip driver powersupply with TL494 and It dose'nt seems to create any noise.Are there any better IC's other than TL494 and SG3525 which has much lower output noice level and a good builtin feedback circuit, or should i continue with TL494 ?

author: jmelson
author_rank: Super Contributor
timestamp: December 31, 2024, 06:57:44 pm
content: The noise from the driver IC will be microscopic compared to the noise from a 1000 W power supply. It may be possible to put the supply in a separate, shielded box and place RC filtering at the output. But, using a switching power supply in audio equipment is going to be a bit difficult.Jon

author: janoc
author_rank: Super Contributor
timestamp: December 31, 2024, 11:36:42 pm
content: Given that it is for 1kWoutputthat supply would need to provide probably 2x as much if not more, depending on how efficient (or not) that amplifier is.Building a 1kW amp as a beginner with limited experience (judging from where it has been posted) is probably not the smartest idea, IMO.

author: Herschel
author_rank: Regular Contributor
timestamp: January 01, 2025, 01:45:35 am
content: Quote from: jmelson on December 31, 2024, 06:57:44 pmfor the amplifier, the powersupply, poweramplifier and the preamp with equilizer are in seperate metal boxes (like a rack type music system). I have already tested my amplifier at its full power and it did finethe only problem is the noise from the audio output of the amplifier when not playing a music.I did try changing the sg3525 with IR2153, the noise at the output reduced a bit, but it was a different noiselater found out it was due to the sg3525 switching noise

author: Herschel
author_rank: Regular Contributor
timestamp: January 01, 2025, 01:49:23 am
content: Quote from: janoc on December 31, 2024, 11:36:42 pmthe powersupply i made was able to produce nearly 1500watts. but the noise at the output of speakers was the only problem...also I'm not sure where to post this topic...

author: Herschel
author_rank: Regular Contributor
timestamp: January 01, 2025, 08:45:43 am
content: Is this transformer noise caused by PWM burst or pulse skipping? also the inductor values i used are pretty high more than the 20uH inductors used hereThis from an another articlehttps://www.diysmps.com/forums/index.php?threads/sg3525-ir2110-50khz-900w-smps-question.708/also a small modification in feed back circuit is said to do the job...

author: MathWizard
author_rank: Super Contributor
timestamp: January 01, 2025, 09:08:17 am
content: It's no big deal, but this would probably go in the Project's/Design's/Technical page

author: Herschel
author_rank: Regular Contributor
timestamp: January 04, 2025, 07:27:23 am
content: I think, I might have solved the issueA) transformer making a high frequency sound affecting the output audio:output inductors where meant to be 20 uH but I used one of 30 uH (calculated with coil 32 as i don't have a meter to measure inductance)B) transformer making a ticking sound while operation and may gets reduced under loads (you can hear this in the speaker outputs):replaced the 4n25 optocoupler with PC817C) PowerAmp output gets clipped under high volumes:snubber circuit should be used before the SMPS tranformer input after the mosfets and after the output inductors (20uH). I forgot to use them(this problem not only happens with base, but also with the mid frequencies)Also make sure the transformer frequency is not too high.(the tranformer core will be the one that gets warm instead of the windings reducing its effiency)BUT, why did replacing the 4n25 optocoupler with PC817 soved the issue?

author: Andy Chee
author_rank: Super Contributor
timestamp: January 04, 2025, 08:15:58 pm
content: Quote from: Herschel on January 04, 2025, 07:27:23 amOptocouplers have a specification called CTR Current Transfer Ratio. This spec has a significant impact on control loops.Unfortunately CTR can vary a lot. In order to deal with it, you need to;a) make your design tolerance wider, and/orb) measure the CTR and select a device with adequate spec