5V Regulator for Automotive application.

Discussion in 'The Projects Forum' started by Geoffr67, Dec 5, 2011.

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  1. Geoffr67

    Thread Starter Member

    Dec 5, 2011
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    Hello,
    I am posting in hope the more seasoned vetrans here can give me some input on how to construct a Stable 5v regulator for use in a noisey Automotive enviorment i need just under 2 amps of current so i am looking at the LM323T 3A linear vreg in the to-220 case i plan to put a large heatsink on this to dissipate heat generated. My question is what would be the best choice in capacitors to Filter the output? Also is there anything i can do to provide some sort of protection to the regulator itself (diodes) Im sorry if my question seems very beginner. But this is the first time im going to use one in a noisy automotive enviorment and need a stable clean voltage.
    Thank you all for reading my questions and i look forward to hearing your ideas!
    Geoff
     
  2. T.Jackson

    New Member

    Nov 22, 2011
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    Arr you can go with the cheaper 1A reg and use a series pass trans-resistor transistor.

    You want to go with this one?
     
  3. Geoffr67

    Thread Starter Member

    Dec 5, 2011
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    id like to keep the circuit simple and the lowest parts count as possible. while having reliability in the harsh automotive enviorment. Id really like to use the LM323T because i think it would be most simple for me.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    Automotive applications are usually taboo here, but some exceptions do exist. Truth to tell I'm still trying to figure the rules out myself. Before this thread goes much further could you fill us in on what you are trying to do?

    I may have to close this thread, but I want to give you a chance to explain your application first. Read out TOS (Terms of Service) at the bottom of this page to find out more.
     
  5. Geoffr67

    Thread Starter Member

    Dec 5, 2011
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    i am designing a simple logic in pic basic to switch on an off some simple Vacume solenoids on a turbocharged Sandrail i built. the solenoids will be used to switch boost levels of the turbocharger. while i could easily buy something off the shelf, ive always had an interest in electronics and would like to be able to make this myself.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The LM323T will shut down or burn up on you due to the power dissipation.

    2A * 5v = 10 Watts; that's the power dissipation of your load.
    When the alternator is charging, it's putting out roughly 13.8v to 14.2v. Let's call it 14v.
    14v-5v = 9v; 9v*2A = 18 Watts.

    Total of 28W power dissipation, and 18 of that is in the regulator. Just a tad under 36% efficiency.

    You'd need a really big heat sink.

    The regulator is designed for an absolute maximum input of 20v. In an automotive electrical system, you routinely get "load dumps" which cause voltage spikes exceeding 60v. The first time a load dump occurred, the regulator would be toast.
     
    Last edited: Dec 6, 2011
  7. T.Jackson

    New Member

    Nov 22, 2011
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    Do you require an explanation on how it works, or do you feel it to be simple enough?
     
  8. Geoffr67

    Thread Starter Member

    Dec 5, 2011
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    I appreciate the Help guys,is there anything i could do that would reduce the parts count of what T.Jackson has posted? or alternatives that would not require many components. i am trying to package something in a small box and plan on writing my logic to a Surface mount pic chip. one of my goals is to keep it as small as possible.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    I was afraid of this.

    The All About Circuits forum Administrative Team has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

    This thread is against the AAC forum rules, Chapter 6, as seen here:

    http://www.allaboutcircuits.com/l_tos.html


    Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

    Please try to understand the reasons behind this action, and feel free to browse and use the forums.

    You might find answers to your questions in one of these forums:

    http://forum.allaboutcircuits.com/sh...ad.php?t=54400
     
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