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LM5010: LM5010 layout issues

Anurag Kumar2
Prodigy 180 points
Part Number: LM5010

Hi,

We are trying to achieve 10V/1A using LM5010 with Input voltage range of 12V-70V.

At 12V-24V, its gives 9.4V at 1A.

And above that, like at 36V, 48V. It drops till 9.4V at 0.5A and 2V at 1A.

Following is the waveform for Switching output(yellow), Vout(green) and Fb(Blue):

Another issue is that, as I am varying load current above 500mA, Feedback voltage is falling from 2.5V to 2.4-2.3 and so on.

This is my layout and schematic, if someone can review it:

Regards,

Anurag

  • 0
    TI__Genius 10685 points

    Hello Anurag,

    Thank you for sharing your schematic and layout. Your schematic looks fine, however your layout could be improved. The connection between the diode and the ISEN pin should be shorter and thicker as this is part of the power path. The same goes for the SW node connection.

    Do you notice a reduction in the switching frequency between the following two cases:

    When Input Voltage=12V-24V, 10Vout, 1A vs. when the input voltage=36V-48V, 10Vout, 1A?

    If the switching frequency does indeed drop, then it may indicate that the device current limit is being sensed which is causing the converter to limit the output current and cause the output voltage to drop below the desired set point.

    Regards,

    Harrison Overturf

  • 0 in reply to Harrison Overturf
    TI__Mastermind 28020 points

    Hi Anurag,

    We have not heard back from you in several weeks. I hope this means that you have resolved your issue.

    If support is still needed, please let us know.

    Thanks, Jason

  • 0 in reply to J Arrigo
    Prodigy 180 points

    Hi,

    Thanks for your response.

    I have noticed reduction in switching frequency.

    But, I haven't been able to get a new PCB to test it out, though.

    Regards,

    Anurag

  • 0 in reply to Anurag Kumar2
    TI__Mastermind 28020 points

    Hi Anurag,

    Please let us know if you are still having questions after you receive the new PCBs.

    Regards, Jason