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  • TI Thinks Resolved

LM2731: Why does the Vout change bigger?

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Replies: 7

Views: 1872

Part Number: LM2731

Dears:

From the datasheet when the VOUT is 12V, and the Iout is 500mA.

However, when we test our board Vout will change bigger  if the load is bigger.

Could you kindly help to check the schematic and give some suggestions about the issue?

Thanks a lot!

Best regards!

Luck Wu

Thanks a lot!

Best regards

Luck Wu

  • Hi Luck

      Firstly, please check the power supply's current limit, you can set it ahout 2A.

    If there is still an issue, could you describe the issue clearly?

    How much current is the bigger load?

    Could you test the Vout, SW and Vin waveforms? It will be helpful for me to analysis the problem.

    Best Regards,

    Jing Ji

    Step-up (boost) Switching Regulator Solutions

  • In reply to Jing Ji:

    Thanks a lot for your reply,can you tell me how to set the current limit to 2A?
  • In reply to Jing Ji:

    Thanks a lot for your reply,
    can you tell me how to set the current limit to 2A?
  • In reply to gaogao01:

    Hi gaogao

      set power supply's current limit depends on your power supply equipment. You can check the instruction of your power supply.

      another way, you can check the Vin waveform to check if power supply is current limit or not.

    Best Regards,

    Jing Ji

    Step-up (boost) Switching Regulator Solutions

  • In reply to Jing Ji:

    Hi,Jing
    I could't understand the method of adjusting the power supply's current limit(such as 2A),Could you explain it again?
    By the way,If I use a electrolytic capacitor(the value is 100uF)at the output of LM2731 as the schematic as shown。
    Is there any influence about the output voltage of LM2731?


    Thanks and Best Regards!
    Gao
  • In reply to gaogao01:

    Hi Gaogao

      there is a easy way to check power supply's current limit, when the LM2731 works, you can test input voltage to check it is stable or not.

      you can put a 100uF electrolytic cap in the output. it will make output ripple smaller.

    Best Regards,

    Jing Ji

    Step-up (boost) Switching Regulator Solutions

  • In reply to gaogao01:

    Hi Gao
    Did you solve the problem?
    if not, could you describe the problem in detail and tell me the value of Vout and Iout.
    Could you test some waveform for me? switching node, FB node and Vin?
    it will be helpful for me to analysis the issue.

    Best Regards,

    Jing Ji

    Step-up (boost) Switching Regulator Solutions

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