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Linear or switching regulator?

Discussion in 'General Electronics Discussion' started by Gergo, Sep 11, 2017.

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  1. Gergo


    Jul 23, 2017
    For my microcontroller based system, I need regulated 5V from a 24VDC input supply. Should I design the power supply unit with a switching regulator, or is it fine if I just use a simple LDO, capable of accepting 24V input voltage? As I saw, its cheaper and less complicated circuitry. What do you think?
  2. kellys_eye


    Jun 25, 2010
    Depends what you feel is acceptable 'losses' in the system.

    For a simple LDO regulator and 5V drawing 3A you will have to drop 19V @ 3A in the regulator - a power loss (heat dissipation) of some 27 watts.......

    A switching regulator might have 90% efficiency so losses would be only 2.7W

    Sounds like a simple choice to me......

    Equally, you usually only use LDO regulators when the input voltgae is close to the output voltage - it's probably irrelevant but that's what LDO regulators were designed for.
    Gergo likes this.
  3. Gergo


    Jul 23, 2017
    Sounds reasonable, thank you! :)
  4. BobK


    Jan 5, 2010
    Well, it depends on the current. If you are using only 1mA, the wasted power is only 19mW , and a linear regulator is a no brainer. The changeover point is probably somewhwe in the region of 50mA, which results in 1W of loss, which can be handled by a TO220 case woth no heat sink.

    Gergo likes this.
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