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LM2576 ADJ Noise in Audio App

James Miler
Prodigy 60 points
Other Parts Discussed in Thread: LM2576

Dear all!

I made a power supply use two 2576 ADJ for my fuzzs. I use a transformer 220V to 18V/ 5A (AC), output voltage of diode bridge is 20-22V DC, capacitor after diode bridge is 2200uF. Output voltage of the power supply is 9V and I made 4 outputs from each 2576.

If I use all 4 outputs of a 2576, it's OK. But when I use 2 outputs of a 2576 and 2 outputs from another, it's so noise in my amp. I think having some problem in output power, my fuzz is Boss GT2, Boss NS2, Boss DD 20 and TS7 Tubescreamer

Can you help me fix it?

Thank you!

  • 0
    TI__Genius 15810 points

    Hello James,

    I am not quite clear about your problem. From your schematic it looks like you have two LM2576 regulators and  you have an extra L-C filter at the output of each regulator. The LM2576 is a single channel buck regulator and has only one output. Adding a second stage L-C helps to filter the output of the LM2576. It would not mean that it is another output. Therefore, currently you have two outputs from the two LM2576s.

    Also, calculating the extra L-C filter values properly is important. If you do not have the optimum values, the filter will interfere with the stability of the LM2576. Would you please tell us where you obtained the BOM components from? Also what is your load requirement from the LM2576?

    Regards,
    Akshay 

  • 0 in reply to Akshay Mehta
    Prodigy 60 points

    Hi Akshay Mehta,

    From an output of LM2576, I link to four dc jack 3.5mm parallely, like a power distributor:

    About extra L-C filter I use value in datasheet, L is 20uH and C is 100uF.

    Thank you!