A way around to cheaper LM317K voltage regulator.

Discussion in 'Analog & Mixed-Signal Design' started by Kuki Muki, Oct 3, 2018.

  1. Kuki Muki

    Thread Starter New Member

    Apr 3, 2018
    11
    0
    Hello there,i wanted to build an power supply,but LM317T specifications are under the requirements,because my supply can output 1.5A,but LM317T can only control up to 0.8,and there is another variation called LM317K which is just right for my requirements(1.5A),but costs 13$ more.
    So i thought if we could use two LM317T as one shown in the circuit bellow:
    [​IMG]
    So i though this maybe would get the job done,still i am not sure about those passive components values,and those are what i found on the internet.
    And these two would get a heatsink and a fan.
    Thanks you in advance!
     
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
    7,440
    1,763
    A more typical approach to increase current capacity would be to use an external pass transistor. Examples should be in the datasheet.
     
  3. ericgibbs

    Moderator

    Jan 29, 2010
    6,209
    1,178
  4. danadak

    Well-Known Member

    Mar 10, 2018
    1,905
    395
    Do NOT parallel regulators like that because they do not
    have a current sharing mechanism (in circuit you posted).
    Thats because their Vref error amp and reference are not
    matched, device to device.

    Regards, Dana.
     
  5. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    7,605
    1,261
    You need a Pass Transistor like this circuit, make Rb 22 to 47 ohms, put power transistor on an heatsink, or use a TIP147.

    lm317pass1.jpg
     
Loading...