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LM43601: Inverting configuration not regulating above 150mA

Part Number: LM43601

Requirements +5Vin, -15Vout @ 0.3A

Circuit designed from Webench using these specs. When prototyped, it does not regulate well above 150mA. Even at this modest load, inductor gets hot but -15V is present. Above 150mA, regulation is lost and droops to around -8V. Also this regulator would not start up into a very light load (20mA) without a 22n capacitor connected to the SS pin.

  • Hello,

    Thank you for sharing the schematic for your design.

    Would you be able to help share additional information about this design?

    1. Can you share the inductor part number?
    2. Can you share the PCB layout?
    3. Do you have an oscilloscope waveform of VIN, SW, VOUT when the output voltage drops to -8V above 150mA and one waveform when the device is regulated at -15?

    Thank you,
    Katelyn
  • Hello,

    I want to follow up with you. Would you be able to share additional information about this design?

    1. Can you share the inductor part number?
    2. Can you share the PCB layout?
    3. Do you have an oscilloscope waveform of VIN, SW, VOUT when the output voltage drops to -8V above 150mA and one waveform when the device is regulated at -15?

    Thank you,
    Katelyn
  • Hello,

    I want to follow up with you. Are you still seeing this issue? If so, could you help share additional information about this design?

    1. Can you share the inductor part number?
    2. Can you share the PCB layout?
    3. Do you have an oscilloscope waveform of VIN, SW, VOUT when the output voltage drops to -8V above 150mA and one waveform when the device is regulated at -15?

    Thank you,
    Katelyn
  • Hello,

    Due to inactivity, I am going to close this thread. Please feel free to respond to this thread if you have any additional questions.

    Best Regards,
    Katelyn