Voltage regulator differences

  • Still trying to expand my skill set. Using the newbie PCB, I need to have a regulator to take the 5v output of a mini pro down to 3.3 for the radios. Looking around I see several options. Ld1117, lm317 and lm33 are a few of them. Looks like they all take it down to 3.3v. After researching online there are many opinions as to which to use. I’m still learning and some (most) of these words are foreign to me but can someone explain the differences between the 3? Or is there a better option? Thanks in advance.

  • @thecricketer
    There are so many things to consider when selecting components but for us hobby-tinkerers there are a few that are most important e.g.
    Max input voltage: Vinmax
    Max output current: Iout
    Size or package

    You will find all these answers in the data sheets. Normally available from your components supplier or else on the internet. Below is a simple table:

    Type Vinmax Iout Package Price (SEK, single units)
    LD1117 15 V 800 mA TO220 5:50
    LE33 20 V 100 mA TO92 9:-
    LP2950 30 V 100 mA TO92 9:-
    LM317 40V delta 1500 mA TO220 9:- (There is also an 100 mA version for 6:25)

    If you are using the Sundberg newbiePCB the design is for an TO92 package so either LE33 or LP2950 is the choice.
    The LD1177 is TO220 package and you do not need 800 mA for the radio. It only consumes about 30 mA when transmitting.
    The LM317 is an adjustable regulator so it can regulate to 5 V or 3.3 V or whatever you like but it takes two more resistors to set the voltage. In this case it is overkill and does not fit the Sundberg board.

    If you plan to run your design on batteries I think the LP2950 is better than the LE33 because the LP2950 consumes less power internally, only 75 microamps. The LE33 can use as much as 500 microamps internally.

    This is just scratching the surface of component choice but keep it simple in the beginning.
    Happy tinkering!

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