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LM2611EVAL: output current issue above 8 mA

Part Number: LM2611EVAL
Other Parts Discussed in Thread: LM2611, , LM2776, LM2775

Dear,

  I bought the EV of the LM2611 device. I tested the performances: Vin = 5V

       - Without loads (Iout = 0 mA), the convertor is operationnal

       - If the output current is growing above 8 mA, the EVAL board do not operate correctly. We do not obtain the correct value. We have an issue due to oscillation. The board is loaded by an ideal resistor.

Wer do not understand the origin of this issue. Please, could you help us ?

Thank you in advance.

Best regards!

  • Hello Ludovic,

    Thanks for reaching out to us via e2e.

    Please make sure that your lab supply is not running into a current limit. Please be aware that the necessary peak current can be much higher than the average current.

    Sometimes, there are issues with the combination of different lab supplies, DC/DC converters and electronic loads.
    Internally all of them are basically switch mode converters and some combinations show strange effects.

    Therefore, please try using a different lab supply and load.

    Best regards,
    Harry

  • We improve the current limitation to 100 mA much more than the 30 mA required. It does not produce effects.

    Best regards

  • Hi Ludovic,

    LM2611EVAL can handle -5V/300mA, so please check your setup.

    Have you checked input voltage when the problem happened? Are you using a resistor as the load?

    Best Regard,

    Feng Ji

  • Hi Feng,

       Yes I have chack the resitor value. It is correct. Besides, the power supply can handle such current. Nevertheless we limit the current at 80 mA in order to keep safe the EVAL.

    Best regards

    Ludovic Bacqué

  • We have a resitor and we use your EVAL.

  • Hi Ludovic,

    Do you have the waveform of the input voltage?

    You may limit the current at 1A.

    Best Regards,

    Feng Ji

  • Yes we have tested with a higher current limitation. It operate correctly. We are very suprising by the very high initial current!

     Do you have a line-up to propose to us in order to convert a +30V input voltage to a + 5V connected to the LM2611.

     In fact our input voltage is equaled to + 30 V and we need to voltages equalled to +5 V and - 5 V. Do you have any advices? 

    Thank you.

  • Hi Ludovic,

    You need a buck converter for +30V to +5V. You may start a new thread for recommended buck device.

    For +5V to -5V, you may consider charge pump like LM2775 or LM2776.

    Best Regards,

    Feng Ji