Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Please can somebody help me with TDA2050

  1. May 20, 2017 #1
    hello
    please can somebody help me
    i am a begginer
    i understeand everything
    just decoupling capacitor, i dont know te value how to select , of how to calculate
    C10, C7, C5
    TDA2050-Amplifier11.png

    thanks
     
  2. jcsd
  3. May 20, 2017 #2
    The capacitor values are marked on your diagram so what do you need to know?
     
  4. May 20, 2017 #3
    hi Manolis,
    i did not put me the value of components, but i find in the internet the circuit(searching for TDA2050, i need for audtio amplifier(i have chip TDA2050),
    and i know all other component value to calculate, but only DECOUPLING capacitor i dont know,
    because Manolis i am beginner, i hope you understand me.
    thnx
     
  5. May 20, 2017 #4

    lewando

    User Avatar
    Gold Member

    What type of power supply will this circuit be using--linear regulator, switching regulator, or battery? How far away will the power supply be from this circuit? Is your plan to build this or simulate only?
     
  6. May 20, 2017 #5
    battery, maybe 1cm , my plan is to build.
     
  7. May 20, 2017 #6
    The value of the decoupling capacitor doesn't matter. What matters is its effective impedance at various frequencies - low to high. The 3 capacitors are chosen to provide a low impedance across the range of frequencies to prevent oscillation.
     
  8. May 20, 2017 #7

    lewando

    User Avatar
    Gold Member

    It is good that you will be building it. Hopefully you are doing a prototype before a PCB. During the prototype build, use those values as a starting point. You got those values from somewhere so perhaps you have specific capacitor part numbers to work with. Make sure the voltage rating of the capacitor can handle the voltage rails. When you have your prototype built, evaluate it. If you are happy with it, you could be done. If you want to learn about the effects of your capacitor selection, experiment by removing them, adding them back one at a time, etc.
     
  9. May 20, 2017 #8

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    Search on bypass capacitor selection
    it's a skill of its own
    in general "more is better"
    but big capacitors, because they're made by coiling a strip of aluminum foil have inductance , and at high frequency no longer behave like a capacitor.
    and that's why you usually see a big one paralleled by a tiny one.


    http://www.intersil.com/content/dam/Intersil/documents/an13/an1325.pdf

    https://www.allaboutcircuits.com/te...-2-choosing-and-using-your-bypass-capacitors/

    https://electronics.stackexchange.c...alue-of-0-1uf-for-bypass-capacitors-come-from
     
  10. May 20, 2017 #9
    thank you for answer, but my problem is i want to know(how it works) because i can use those value, but i dont understand how it works.
     
  11. May 20, 2017 #10
  12. May 20, 2017 #11

    lewando

    User Avatar
    Gold Member

    Have you read and comprehended any of @jim hardy 's excellent links? There is a lot of insight in contained in them. You could then ask more specific questions.
     
    Last edited: May 20, 2017
  13. May 20, 2017 #12
    thnx , but i have very difficult to understand, is possible to explain me a little bit, with e few word,
     
  14. May 20, 2017 #13
    you right ;-)
     
  15. May 20, 2017 #14

    lewando

    User Avatar
    Gold Member

    I understand you are up against a language barrier. I cannot reduce the information in those links in a more meaningful way. All I can tell you is that the selection process is a very general process based on the operating frequency range of your circuit. When you have realized your circuit (built it), you can begin a specialized process of optimizing capacitor values to make your circuit perform better, if necessary.

    What is your operating frequency range?

    After you build it, how will you test it to see if it a good (passes some criteria) or bad (fails some criteria) circuit?
     
  16. May 21, 2017 #15

    thanks for advice,i still not build, because i had no time, but this week for sure i want to build.
     
  17. May 21, 2017 #16

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award



    The basic idea of decoupling is to keep the power supply voltage stable when the amplifier takes a sudden gulp of current.
    If the power supply voltage changes , it will affect the amplifier's output slightly. By how much is indicated by the amplifier's "Power Supply rejection Ratio" .

    That is given in the datasheet, at http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000131.pdf
    page 3

    upload_2017-5-21_22-26-9.png

    as only 45 db@100 hz.
    Since the amplifier has feedback, that change in output will get coupled around to the input
    and when phase shift becomes 180 degrees what was intended as negative feedback becomes positive and it'll oscillate.
    Power supply rejection typically becomes less as frequency increases so it's important to have steady voltage right at the amplifier pins.


    See this application note
    http://www.analog.com/media/en/training-seminars/tutorials/MT-043.pdf
    upload_2017-5-21_22-31-28.png

    Since each type of device has its own gain, frequency response, and power supply rejection ratio , selection of decoupling capacitors is best left to the designer of the device. He will give you his suggested values. Here's what he put in the TDA2050 datasheet for you to use.
    upload_2017-5-21_22-44-50.png
    It is important they be located physically close to the amplifier pins so as to minimize inductance of the interconnecting wires.


    That Analog Devices tutorial makes it clear why you need both a low frequency and a high frequency bypass capacitor. That's C10 and C5 (and C6 & C9) in your example.
    I don't know what is the purpose of the 100 uf C7 in your example.

    And that's the best answer i can give.
     
    Last edited: May 21, 2017
  18. May 22, 2017 #17

    Thank you very much it help me...
    have a nice week.
     
  19. May 22, 2017 #18

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    Interesting,
    in your example schematic they drew the high frequency decoupling capacitor closest to the pins , as it should be physically. That's good draftsmanship.

    Thanks for the kind words , and good luck with your project ! old jim
     
  20. Jun 2, 2017 #19
    thank you very much
    have a nice wekend.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted