Connect with us

Regulators filters out ripple?

Discussion in 'General Electronics Discussion' started by TommyF, May 19, 2015.

Thread Status:
Not open for further replies.
Scroll to continue with content
  1. TommyF

    TommyF

    13
    0
    May 18, 2015
    How does a Linear or switching Regulator chip filter out ripple?

    The ripple percentage is filtered out even more when it passes through a regulator chip. I don't see any filtering components inside a regulator chip to filter out ripple.
     
  2. davenn

    davenn Moderator

    13,798
    1,939
    Sep 5, 2009
  3. TommyF

    TommyF

    13
    0
    May 18, 2015
    yes it's called the PSRR

    it eliminates the ripple so how
     
  4. davenn

    davenn Moderator

    13,798
    1,939
    Sep 5, 2009
    lets take the 78/79xx series linear reg

    here's the block diag

    78xx series block.GIF

    The error amplifier using the reference voltage is going to do all it can to keep any variations in the output voltage to a minimum
    it will compensate for variations in voltage on the input. And that is all ripple is ... a slight variation in the DC voltage


    Dave
     
    hevans1944 likes this.
  5. TommyF

    TommyF

    13
    0
    May 18, 2015
    Yes the error amplifier is a comparator , it compares the reference voltage with the output voltage. If there is an difference it will adjust the series pass transistor.

    So it's not filtering out the ripple, it's leveling out the variations to keep it steady
     
  6. TommyF

    TommyF

    13
    0
    May 18, 2015
    Some power supplies are low impedance and other power supplies are high impedance. What is the difference between them and when do you use a low impedance power and when do you use a high impedance power supply?
     
  7. davenn

    davenn Moderator

    13,798
    1,939
    Sep 5, 2009
    and that also (as I said earlier) effectively filters out the ripple

    do you really not understand what ripple is ?
     
  8. TommyF

    TommyF

    13
    0
    May 18, 2015
    Yes it's Smoothing out the ripple by an error amplifier and the series pass transistor

    LDO low drop out regulators use a series pass FET which has no voltage drop and other advantages which i don't know about.
     
  9. TommyF

    TommyF

    13
    0
    May 18, 2015
    Each power supplies technology has different line or load regulation methods.

    When I turn down the AC line voltage under 90VAC until the power supply turns off. The cutting off voltage is between 80vac to 90vac. I'm not sure what sets the cutting off voltage in a power supply.
     
  10. davenn

    davenn Moderator

    13,798
    1,939
    Sep 5, 2009
    probably mainly the combined component values selected in the design
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Thread Status:
Not open for further replies.
Electronics Point Logo
Continue to site
Quote of the day

-