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  • PCB heat up

    If I am using 7805 regulator and it gets heated up. So would it heat up the pcb if I use SMD 7805 and not through hole?

  • #2
    You said "7805 Regulator gets heated up": Did you check for any short?(GND pin with supply pin ). OR Load is trying to draw more current from this.
    How much does the load consumes?
    Currently you're using through hole?

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    • #3
      Yes load is drawing more current. But I can not avoid it. Also, 7805 regulator does get burned. So my point of interest is to save my pcb from heat. If I use through hole, its heat sink gets heated up. Now I want to know if I use SMD, will it heat up the whole pcb or not?

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      • #4
        Yes you cannot control the load current instead why don't you change the regulator to suit your Load current.
        You didn't answer to this."How much current does load draw? Did you check for the short? "
        As I can see from the Data sheet of 7806 can only provide up-to 1.3-1.5A If your load draws more current than this you should change the Regulator and design.
        The problem here is not about through hole/SMD but I think it's the regulator which is not able to give the current which the load requires.
        until unless you specify source and Load specs It's hard to tell what's happening.

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        • #5
          Theoratically, It requires a peak of 2A (only peak current, not continuous and I have never seen this huge current on Ammeter). For continuous operation, it requires 1A current. Yes I am currently using Through hole. The load current is being fulfilled, other wise it does not catch the signals. Only heat sink of regulator heats up. IC provides the required current, it does get burned if I run it for Hours.

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          • Lakshmi
            Lakshmi commented
            Editing a comment
            Even when it says peak current is 2A you must have chosen a regulator with Output current of at least of 2.7-3A.
            You never know when what current load requires.
            Yes if course in your current case IC will burn out.
            You need to change the regulator quickly. Do not use that regulator.

        • #6
          And there is no short circuit. It is the Load that requires this current. Can you suggest me any other IC? I do not want to go for DC-DC converter side, as it consumes a lot of space.

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          • Lakshmi
            Lakshmi commented
            Editing a comment
            As I don't know the Input and Output Voltage It's hard to tell what you require.
            These things need to be taken care by yourself as you've designed the circuit.
            Look for the Output current rating slightly more the actual Output current( I meant more than 2A).
            If you'd ask me i would go with Switching regulator.
            It's not about the Size it's about the efficiency and throughput.
            If there's not much of difference between the Vout and Vin then you can use the LDO. Usually LDO's are preferred when output voltage is very close to the input Voltage(say for eg., If i/p is 5V and Output is 3.3/3.8V then you can go with LDO).
            Since In your case current is bit high I'd recommend you with Switching regulator.

        • #7
          Input is 12V car battery, Output is 5 or 6V.

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          • #8
            Choose which one is suitable for your application from Digikey:
            https://www.digikey.com/products/en/...ors-linear/699

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            • #9
              But my question remains there. Would there be any difference in using SMD instead of Through hole? I mean would it heat up my pcb or not?

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              • #10
                Well that depends on several factor. you could google.
                Wait for some other people to give their verdicts like @robertferanec
                If you're using SMD chose one with the Thermal Pad that way you reduce the heat and dissipates.
                If you chose to go with Through-hole you may have to add external heat sink.
                Last edited by Lakshmi; 06-27-2019, 03:58 AM.

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                • #11
                  Ok, Waiting for his reply

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                  • #12
                    your generating heat because of the drop in voltage.. the 7805 is dissipating that 6Volts stepping down from 12V.
                    regarding your question you can go to SMD, but you have the ensure there is a large GND plane connected with a lot of via's (preferrably multiple planes on different layers)
                    this way the heat can dissipate in the plane and thus it will heat up your PCB. either way some airflow would be recommended.

                    a switching regualtor would be better in this case..

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                    • #13
                      this way the heat can dissipate in the plane and thus it will heat up your PCB.

                      But I want my pcb not to be heated up

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                      • #14
                        then change over to another type of powe supply.. there are plenty of switchmode power supplies that will do what you want. these will not heat up your pcb

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                        • #15
                          Can you please explain? I mean I could not understand switchmode power supplies.

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