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XL4015 Step-Down DC Module

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    XL4015 Step-Down DC Module

    Hi Folks

    I need help in trouble shooting a "XL4015 Step-Down DC Module with CV/CC Control". This is something i am trying to use to create a variable power supply which will allow me to control/limit both voltage and current. This device has an overall limit of 5A.

    But when i am testing this, the voltage control works fine, but the Current control does not. I need help in troubleshooting why the CC is not working. The schematic of this device and the working is explained here Schematic and explanation

    The problem with testing the CC is that i have to short the output to get some visible current and then adjust the potentiometer to get the current current value. But when i short the output, the display shows high current flowing but changing the potentiometer has no impact on the current value. What is surprising is that the current value displayed is 9A when the system is supposed to have a limit of 5A. I tried this on 2 units, both show the same behavior.

    Any ideas ?

    EDIT: found one issue where i had wired the potentiometer wrongly. But correcting that has the following effect. The current (when i short output) always goes to 5A which is the self limit of the system. Moving the potentiometer has no impact on the current. Still continue to be stumped by this.
    Last edited by jinu_j; 02-10-2022, 12:42 AM. Reason: Some more info

    #2
    Re: XL4015 Step-Down DC Module

    Finally solved this. For whatever reason if the output voltage is kept below 2V the CC does not work. I am not sure why. I retested the whole thing with an output of 2V and the CC works perfectly. Below that it does not seem to work.

    Comment


      #3
      Re: XL4015 Step-Down DC Module

      This is not unheard of this is common for these devices to have a voltage higher than the output voltage
      9 PC LCD Monitor
      6 LCD Flat Screen TV
      30 Desk Top Switching Power Supply
      10 Battery Charger Switching Power Supply for Power Tool
      6 18v Lithium Battery Power Boards for Tool Battery Packs
      1 XBox 360 Switching Power Supply and M Board
      25 Servo Drives 220/460 3 Phase
      6 De-soldering Station Switching Power Supply 1 Power Supply
      1 Dell Mother Board
      15 Computer Power Supply
      1 HP Printer Supply & Control Board * lighting finished it *


      These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

      1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
      2 Hem Saw Computer Stack Board

      All of these had CAPs POOF
      All of the mosfet that are taken out by bad caps

      Comment

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