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LM3489-Q1: Buck operation issue and mosfet switching issue

VINAY KUMAR
Prodigy 10 points
Part Number: LM3489-Q1
Other Parts Discussed in Thread: LM3489

the buck converter simulation circuit is given above with LM3489 model.

In this application of input voltage range of 8,12, 18 Volts and output required is of 12V. But what we observed is the output voltage same input, for all the input values.so our question is regarding buck operation.

and the pulse given to mosfet from diver is not switching its turning mosfet continuously on. so we would like to know about mosfet switching also.  

  • 0
    TI__Guru 50120 points

    Hi,

    Can you provide the switching waveform and possibly inductor current for me to understand the behavior of the circuit?

    Also can you provide the PCB layout and make sure that the components were properly soldered/mounted on the the PCB?

    In the mean time I will look through the schematic and comment if I find anything.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Prodigy 10 points

    Hi Jimmy,

    Thank you for your response. sorry to inform you that i am not able to insert or upload the images.

    The switching waveform of the P-Mosfet is continues -8V dc.

    And the inductor current is also continues DC current of 0.4A.

    Regards

    Vinay kumar

  • 0 in reply to VINAY KUMAR
    TI__Guru 50120 points

    Hi Vinay,

    How many units have this issue? Have you tried ABA swap to see if failure follows the IC or the PCB?

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    TI__Guru 50120 points

    Hello,

    I have not heard back from you for some time so I will assume that you were able to resolve the issue on your end.

    Because of this I will be closing this thread. If you have any further question, please reply back to this thread and it will reopen for further discussion.

    Regards,

    Jimmy