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Will linear voltage regulator step up current?


Can a DC regulator reduce/step down DC voltage?Using Linear Voltage Regulators in Series?What is used to reduce to 220v AC voltage to lower voltage for DC conversionChoosing a linear regulator vs. switching regulator for low-power application?Setting a step-down regulator to provide constant drop on the following linear regulatorLinear regulator with external switchLinear voltage regulator currentBest design choice: linear regulator or switch converterSwitching pre regulator and linear regulatorsAny downside to feeding a buck regulator into a linear one?













2












$begingroup$


I have a regulated 9 volt 300mA power supply I want to step it down to 5 volt using Linear Voltage Regulator LM7805 , I want to know how much current can I can draw at 5 volts, will it be 300mA or will it be close to 540mA, since power = voltage * current.










share|improve this question







New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • $begingroup$
    With a 9V*0.3A=2.7W supply you can only achieve >90% efficiency with an SMPS to store energy and transfer with rapid switching.
    $endgroup$
    – Sunnyskyguy EE75
    2 hours ago
















2












$begingroup$


I have a regulated 9 volt 300mA power supply I want to step it down to 5 volt using Linear Voltage Regulator LM7805 , I want to know how much current can I can draw at 5 volts, will it be 300mA or will it be close to 540mA, since power = voltage * current.










share|improve this question







New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$












  • $begingroup$
    With a 9V*0.3A=2.7W supply you can only achieve >90% efficiency with an SMPS to store energy and transfer with rapid switching.
    $endgroup$
    – Sunnyskyguy EE75
    2 hours ago














2












2








2





$begingroup$


I have a regulated 9 volt 300mA power supply I want to step it down to 5 volt using Linear Voltage Regulator LM7805 , I want to know how much current can I can draw at 5 volts, will it be 300mA or will it be close to 540mA, since power = voltage * current.










share|improve this question







New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




I have a regulated 9 volt 300mA power supply I want to step it down to 5 volt using Linear Voltage Regulator LM7805 , I want to know how much current can I can draw at 5 volts, will it be 300mA or will it be close to 540mA, since power = voltage * current.







power-supply linear-regulator






share|improve this question







New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 2 hours ago









Jayant PahujaJayant Pahuja

111




111




New contributor




Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Jayant Pahuja is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • $begingroup$
    With a 9V*0.3A=2.7W supply you can only achieve >90% efficiency with an SMPS to store energy and transfer with rapid switching.
    $endgroup$
    – Sunnyskyguy EE75
    2 hours ago


















  • $begingroup$
    With a 9V*0.3A=2.7W supply you can only achieve >90% efficiency with an SMPS to store energy and transfer with rapid switching.
    $endgroup$
    – Sunnyskyguy EE75
    2 hours ago
















$begingroup$
With a 9V*0.3A=2.7W supply you can only achieve >90% efficiency with an SMPS to store energy and transfer with rapid switching.
$endgroup$
– Sunnyskyguy EE75
2 hours ago




$begingroup$
With a 9V*0.3A=2.7W supply you can only achieve >90% efficiency with an SMPS to store energy and transfer with rapid switching.
$endgroup$
– Sunnyskyguy EE75
2 hours ago










2 Answers
2






active

oldest

votes


















7












$begingroup$

No. A linear regulator works by burning off excess voltage as heat, therefore current in equals current out. The linear regulator is essentially throwing away the excess energy in order to regulate, rather than converting it to the output. You need a switching regulator if you want to take advantage of power in equals power out in order to convert a high input voltage, low input current into a lower output voltage, higher output current.



$P_{in} = P_{out}$



but for a linear regulator it looks like this:



$V_{in} times I_{in} = (V_{out} times I_{out}) + [(V_{in} - V_{out}) times I_{out}]$



The last term in square brackets is the excess voltage being converted to heat. If we expand and simplify the right hand side, a bunch of things cancel out and we get:



$V_{in} times I_{in} = V_{in} times I_{out}$



Therefore:



$I_{in} = I_{out}$






share|improve this answer










New contributor




Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$













  • $begingroup$
    I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
    $endgroup$
    – Sparky256
    2 hours ago










  • $begingroup$
    Thanks. I changed the sentence structure halfway through but missed changing "burn".
    $endgroup$
    – Toor
    2 hours ago












  • $begingroup$
    @Toor * means convolution and not a multiplication.
    $endgroup$
    – Jan
    1 hour ago










  • $begingroup$
    Right. How lemme try and figure out how to get a multiplication sign in there.
    $endgroup$
    – Toor
    1 hour ago










  • $begingroup$
    Changed. It's rather inelegant to need to go "times"
    $endgroup$
    – Toor
    1 hour ago





















1












$begingroup$

No, it won't step up current. You can think of a regulator as a resistor that adjusts it's resistance to keep the voltage stable.



However, you can buy DC to DC converters that 'boost' the current. But DC to DC converters are usually called by what they do to the voltage, not the current.



A boost converter 'boosts' or steps up the voltage from a lower voltage to a higher one (at the expense of current and a small loss in power)



A buck converter or step down converter takes a higher voltage into a lower one (with potentially more current than is on the input of the converter, also with a small loss)



They actually make 78XX series DC to DC converters that are drop in compatible with linear regulators that buck or boost voltage.






share|improve this answer









$endgroup$













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    2 Answers
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    active

    oldest

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    2 Answers
    2






    active

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    active

    oldest

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    active

    oldest

    votes









    7












    $begingroup$

    No. A linear regulator works by burning off excess voltage as heat, therefore current in equals current out. The linear regulator is essentially throwing away the excess energy in order to regulate, rather than converting it to the output. You need a switching regulator if you want to take advantage of power in equals power out in order to convert a high input voltage, low input current into a lower output voltage, higher output current.



    $P_{in} = P_{out}$



    but for a linear regulator it looks like this:



    $V_{in} times I_{in} = (V_{out} times I_{out}) + [(V_{in} - V_{out}) times I_{out}]$



    The last term in square brackets is the excess voltage being converted to heat. If we expand and simplify the right hand side, a bunch of things cancel out and we get:



    $V_{in} times I_{in} = V_{in} times I_{out}$



    Therefore:



    $I_{in} = I_{out}$






    share|improve this answer










    New contributor




    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    $endgroup$













    • $begingroup$
      I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
      $endgroup$
      – Sparky256
      2 hours ago










    • $begingroup$
      Thanks. I changed the sentence structure halfway through but missed changing "burn".
      $endgroup$
      – Toor
      2 hours ago












    • $begingroup$
      @Toor * means convolution and not a multiplication.
      $endgroup$
      – Jan
      1 hour ago










    • $begingroup$
      Right. How lemme try and figure out how to get a multiplication sign in there.
      $endgroup$
      – Toor
      1 hour ago










    • $begingroup$
      Changed. It's rather inelegant to need to go "times"
      $endgroup$
      – Toor
      1 hour ago


















    7












    $begingroup$

    No. A linear regulator works by burning off excess voltage as heat, therefore current in equals current out. The linear regulator is essentially throwing away the excess energy in order to regulate, rather than converting it to the output. You need a switching regulator if you want to take advantage of power in equals power out in order to convert a high input voltage, low input current into a lower output voltage, higher output current.



    $P_{in} = P_{out}$



    but for a linear regulator it looks like this:



    $V_{in} times I_{in} = (V_{out} times I_{out}) + [(V_{in} - V_{out}) times I_{out}]$



    The last term in square brackets is the excess voltage being converted to heat. If we expand and simplify the right hand side, a bunch of things cancel out and we get:



    $V_{in} times I_{in} = V_{in} times I_{out}$



    Therefore:



    $I_{in} = I_{out}$






    share|improve this answer










    New contributor




    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    $endgroup$













    • $begingroup$
      I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
      $endgroup$
      – Sparky256
      2 hours ago










    • $begingroup$
      Thanks. I changed the sentence structure halfway through but missed changing "burn".
      $endgroup$
      – Toor
      2 hours ago












    • $begingroup$
      @Toor * means convolution and not a multiplication.
      $endgroup$
      – Jan
      1 hour ago










    • $begingroup$
      Right. How lemme try and figure out how to get a multiplication sign in there.
      $endgroup$
      – Toor
      1 hour ago










    • $begingroup$
      Changed. It's rather inelegant to need to go "times"
      $endgroup$
      – Toor
      1 hour ago
















    7












    7








    7





    $begingroup$

    No. A linear regulator works by burning off excess voltage as heat, therefore current in equals current out. The linear regulator is essentially throwing away the excess energy in order to regulate, rather than converting it to the output. You need a switching regulator if you want to take advantage of power in equals power out in order to convert a high input voltage, low input current into a lower output voltage, higher output current.



    $P_{in} = P_{out}$



    but for a linear regulator it looks like this:



    $V_{in} times I_{in} = (V_{out} times I_{out}) + [(V_{in} - V_{out}) times I_{out}]$



    The last term in square brackets is the excess voltage being converted to heat. If we expand and simplify the right hand side, a bunch of things cancel out and we get:



    $V_{in} times I_{in} = V_{in} times I_{out}$



    Therefore:



    $I_{in} = I_{out}$






    share|improve this answer










    New contributor




    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    $endgroup$



    No. A linear regulator works by burning off excess voltage as heat, therefore current in equals current out. The linear regulator is essentially throwing away the excess energy in order to regulate, rather than converting it to the output. You need a switching regulator if you want to take advantage of power in equals power out in order to convert a high input voltage, low input current into a lower output voltage, higher output current.



    $P_{in} = P_{out}$



    but for a linear regulator it looks like this:



    $V_{in} times I_{in} = (V_{out} times I_{out}) + [(V_{in} - V_{out}) times I_{out}]$



    The last term in square brackets is the excess voltage being converted to heat. If we expand and simplify the right hand side, a bunch of things cancel out and we get:



    $V_{in} times I_{in} = V_{in} times I_{out}$



    Therefore:



    $I_{in} = I_{out}$







    share|improve this answer










    New contributor




    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    share|improve this answer



    share|improve this answer








    edited 25 mins ago





















    New contributor




    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    answered 2 hours ago









    ToorToor

    3917




    3917




    New contributor




    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.





    New contributor





    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    Toor is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.












    • $begingroup$
      I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
      $endgroup$
      – Sparky256
      2 hours ago










    • $begingroup$
      Thanks. I changed the sentence structure halfway through but missed changing "burn".
      $endgroup$
      – Toor
      2 hours ago












    • $begingroup$
      @Toor * means convolution and not a multiplication.
      $endgroup$
      – Jan
      1 hour ago










    • $begingroup$
      Right. How lemme try and figure out how to get a multiplication sign in there.
      $endgroup$
      – Toor
      1 hour ago










    • $begingroup$
      Changed. It's rather inelegant to need to go "times"
      $endgroup$
      – Toor
      1 hour ago




















    • $begingroup$
      I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
      $endgroup$
      – Sparky256
      2 hours ago










    • $begingroup$
      Thanks. I changed the sentence structure halfway through but missed changing "burn".
      $endgroup$
      – Toor
      2 hours ago












    • $begingroup$
      @Toor * means convolution and not a multiplication.
      $endgroup$
      – Jan
      1 hour ago










    • $begingroup$
      Right. How lemme try and figure out how to get a multiplication sign in there.
      $endgroup$
      – Toor
      1 hour ago










    • $begingroup$
      Changed. It's rather inelegant to need to go "times"
      $endgroup$
      – Toor
      1 hour ago


















    $begingroup$
    I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
    $endgroup$
    – Sparky256
    2 hours ago




    $begingroup$
    I fixed your minor grammar errors. Takes time to learn details of English. +1 for solid answer.
    $endgroup$
    – Sparky256
    2 hours ago












    $begingroup$
    Thanks. I changed the sentence structure halfway through but missed changing "burn".
    $endgroup$
    – Toor
    2 hours ago






    $begingroup$
    Thanks. I changed the sentence structure halfway through but missed changing "burn".
    $endgroup$
    – Toor
    2 hours ago














    $begingroup$
    @Toor * means convolution and not a multiplication.
    $endgroup$
    – Jan
    1 hour ago




    $begingroup$
    @Toor * means convolution and not a multiplication.
    $endgroup$
    – Jan
    1 hour ago












    $begingroup$
    Right. How lemme try and figure out how to get a multiplication sign in there.
    $endgroup$
    – Toor
    1 hour ago




    $begingroup$
    Right. How lemme try and figure out how to get a multiplication sign in there.
    $endgroup$
    – Toor
    1 hour ago












    $begingroup$
    Changed. It's rather inelegant to need to go "times"
    $endgroup$
    – Toor
    1 hour ago






    $begingroup$
    Changed. It's rather inelegant to need to go "times"
    $endgroup$
    – Toor
    1 hour ago















    1












    $begingroup$

    No, it won't step up current. You can think of a regulator as a resistor that adjusts it's resistance to keep the voltage stable.



    However, you can buy DC to DC converters that 'boost' the current. But DC to DC converters are usually called by what they do to the voltage, not the current.



    A boost converter 'boosts' or steps up the voltage from a lower voltage to a higher one (at the expense of current and a small loss in power)



    A buck converter or step down converter takes a higher voltage into a lower one (with potentially more current than is on the input of the converter, also with a small loss)



    They actually make 78XX series DC to DC converters that are drop in compatible with linear regulators that buck or boost voltage.






    share|improve this answer









    $endgroup$


















      1












      $begingroup$

      No, it won't step up current. You can think of a regulator as a resistor that adjusts it's resistance to keep the voltage stable.



      However, you can buy DC to DC converters that 'boost' the current. But DC to DC converters are usually called by what they do to the voltage, not the current.



      A boost converter 'boosts' or steps up the voltage from a lower voltage to a higher one (at the expense of current and a small loss in power)



      A buck converter or step down converter takes a higher voltage into a lower one (with potentially more current than is on the input of the converter, also with a small loss)



      They actually make 78XX series DC to DC converters that are drop in compatible with linear regulators that buck or boost voltage.






      share|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        No, it won't step up current. You can think of a regulator as a resistor that adjusts it's resistance to keep the voltage stable.



        However, you can buy DC to DC converters that 'boost' the current. But DC to DC converters are usually called by what they do to the voltage, not the current.



        A boost converter 'boosts' or steps up the voltage from a lower voltage to a higher one (at the expense of current and a small loss in power)



        A buck converter or step down converter takes a higher voltage into a lower one (with potentially more current than is on the input of the converter, also with a small loss)



        They actually make 78XX series DC to DC converters that are drop in compatible with linear regulators that buck or boost voltage.






        share|improve this answer









        $endgroup$



        No, it won't step up current. You can think of a regulator as a resistor that adjusts it's resistance to keep the voltage stable.



        However, you can buy DC to DC converters that 'boost' the current. But DC to DC converters are usually called by what they do to the voltage, not the current.



        A boost converter 'boosts' or steps up the voltage from a lower voltage to a higher one (at the expense of current and a small loss in power)



        A buck converter or step down converter takes a higher voltage into a lower one (with potentially more current than is on the input of the converter, also with a small loss)



        They actually make 78XX series DC to DC converters that are drop in compatible with linear regulators that buck or boost voltage.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 48 mins ago









        laptop2dlaptop2d

        25.3k123278




        25.3k123278






















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