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LM2611: Schematic review

Jab
Prodigy 110 points
Part Number: LM2611


Hi,

Could you review the below schematic which is designed for generating -13V from 12.5V input for LCD bias?  Kindly check and let me know if you have any comments.

Parameters that are considered for design:

  • Input voltage: 12.5V
  • Output voltage : -13V
  • output current : 1mA (Max)

Thanks,

Jab

  • 0
    TI__Genius 11215 points

    Hello, 

    Thanks for reaching out. The schematic looks good, the SHDN pin can also be directly connected to the Vin (in case you might prefer this), as the system requires only 1mA of load current then inductors with a lower current rating can also be chosen. Please follow as well the layout guidelines in the datasheet. Let us now if further help is needed. 

    Kind regards,
    EM

  • 0 in reply to EM
    Prodigy 110 points

    Hi EM,

    Thanks for your reply,

    I made up the above schematics by wiring on the LM2611EVAL EVM board. When I power on the device, the input (12.5V) becomes 1.6V, and the output of the regulator was -7.5V.  Could you please let me know why input becomes 1.6V?

    I got the -13V at the output of the regulator after connecting the ground pin of capacitor C388 to Vout (-13_nVGL). This time voltage across the SHDN pin with respect ground pin was 6.5V. can you please let me know why a voltage drop occurred on the SHDN pin?

    Thanks,

    Jab

  • +1 in reply to Jab
    TI__Guru 67685 points

    Hello Jabirali,

    Please share a picture of your setup or explain exactly which component is which on the EVM.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Guru 60991 points

    Hi Jabirali,

    I have not seen an update for the last 13 days, so I assume the questions are/or answered and the issue is solved.
    I close this thread now. If there is still something open reply and the thread will get open again.
    If you have any other question or of the thread gets locked, please open a new one.

    Clicking the Resolved Button also helps us to maintain this forum.

    Best regards,
    Stefan