Connect with us

Cut heatsink tab off 7805

Discussion in 'General Electronics Discussion' started by kickit2, Feb 11, 2012.

Scroll to continue with content
  1. kickit2

    kickit2

    14
    0
    Nov 20, 2011
    Hey everyone.

    I am putting together a circuit which draws only about 30ma from a 7805 (14v input). I'm trying to get everything as small as possible (without going smd) and I want the 7850 to lay flat. Issue is the heatsink tab turns this into a large footprint.

    I'm am assuming that at 30ma the 7805 should do just find with its tab cut off. Can anyone confirm this?

    It is not even getting warm with it on.

    Kickit2
     
  2. Raven Luni

    Raven Luni

    798
    7
    Oct 15, 2011
    At 14v there will be a bit of heat even with 30 mA draw. It is better to keep the tab and use the copper on the bottom of the board as a heatsink.
     
  3. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
  4. BobK

    BobK

    7,680
    1,685
    Jan 5, 2010
    You can get a 78L05 in T092 if you want to save space.

    Bob
     
  5. GonzoEngineer

    GonzoEngineer

    321
    0
    Dec 2, 2011
    Just be careful how you cut it.......you can easily distor tit and fracture the die inside.
    Don't ask me how I know!
     
  6. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    I'm with Bob, with a mere 0.3W of dissipation a 78L05 is the way to go to save space.
     
  7. Raven Luni

    Raven Luni

    798
    7
    Oct 15, 2011
    How do you know :p
     
  8. GonzoEngineer

    GonzoEngineer

    321
    0
    Dec 2, 2011
    Too embarrasing to talk about!
     
  9. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
    Yes the TO92 package can handle the 0.3W, but adding a zener diode at the regulator input can give a bit more headroom (without being too bulky).

    Olivier
     
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.
Electronics Point Logo
Continue to site
Quote of the day

-