Step Down 5VDC, 2A to 3.7VDC, 1A

Discussion in 'General Electronics Chat' started by Rnc Ebm, Aug 14, 2015.

  1. Rnc Ebm

    Thread Starter New Member

    Aug 14, 2015
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    anyone can help me to CONVERT from 5VDC, 2A TO 3.7VDC, 1A using LM317 ?

    my SOURCE is ORIGINAL PSP Charger 5VDC, 2A

    I need only SIMPLE SCHEMATIC for this CIRCUIT, thank you


    best regard
    RNC_EBM
    PHILIPPINES
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    if the 1 amp load were constant, a 1.3 ohm resistor would work.
     
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  3. Rnc Ebm

    Thread Starter New Member

    Aug 14, 2015
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    thanks for the reply, can u give some SIMPLE Schematic with VALUE of the component so that I can make a circuit ?

    NOTE: my source is ORIGINAL SONY PSP CHARGER (5VDC, 2A)


    best regard

    RNC_EBM
    PHILIPPINES
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
    619
    Won't work if the charger output is 5V; dropout voltage of the regulator is around 2V at 1A.
    lm317do.jpg
    Measure the adapter output with a 1.5A load to see what you really have.
     
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  5. TheButtonThief

    Active Member

    Feb 26, 2011
    219
    38
    We need to know more ABOUT your requirements and about the CIRCUIT.

    Is THE load constant? If it is then there's no NEED for an LM317

    WHAT is the load?
     
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  6. Rnc Ebm

    Thread Starter New Member

    Aug 14, 2015
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    okay, thanks, coz I will use this as a TEST BATTERY directly to iPhone4/4s/5/etc.

    any solution to workout to make it 3.7VDC at .5A(500mA) ?


    best regard

    RNC_EBM
    PHILIPPINES
     
  7. Rnc Ebm

    Thread Starter New Member

    Aug 14, 2015
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    0
    THANKS,

    "THE LOAD IS AN iPHONE"

    I will use as a TEMPORARY TEST BATTERY for iPhone4/4s/etc.


    best regard

    RNC_EBM
    PHILIPPINES
     
  8. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
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    Use a rectifier diode, or two, to drop the output to something in the range of the battery.
     
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  9. Rnc Ebm

    Thread Starter New Member

    Aug 14, 2015
    6
    0
    any CIRCUIT DIAGRAM / SCHEMATIC DIAGRAM inorder to make it and the VALUE of the component/s ?

    NOTE: I have this one BELOW (see attached), I want to modify it with the use of ORIG. PSP CHARGER AS A SOURCE

    The 1 BIG PCB is for BATTERY CHARGER, the SMALL PCB's are GOING to iPhone as a TEMPORARY TEST BATT.

    the SUPPLY to charge the battery is 5VDC, and the other one is to supply the iPhone with the VOLTAGE of 3.7VDC, any suggestion ?


    best regard

    RNC_EBM
    PHILIPPINES
     
  10. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
    619
    Measure the output of your charger with no load and a 1.5A load to see if it's really 5V.

    You can use 1N4001 diodes to drop the voltage. Drop depends on current; one diode will drop the voltage around 0.8-0.9V.
     
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  11. Rnc Ebm

    Thread Starter New Member

    Aug 14, 2015
    6
    0

    thanks, i'll try all your suggestions and post result tomorrow, it's 10:37PM-GMT+8 here, thanks again

    best regard

    RNC_EBM
    PHILIPPINES
     
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