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LMR14020 with large output capacitor

Kazuya Nakai59
Guru 21515 points
Other Parts Discussed in Thread: LMR14020

 Hello guys,

 One of my customer is going to use LMR14020 for their products.

 Also they want to use 1mF capacitor as the device output capacitor for driving some ICs which is connected to LMR14020 output shortly after the device input power is shut down.

 But the device output voltage is unstable on their trial board when 1mF is connected to output. I know the capacitor value is too large for LMR14020 but the output capacitor value can not be decreased.

 S. could you please tell me any advice for stable output voltage? If we can not solve the issue, the customer may replace LMR14020 with a competitor part.

 Your advice would be appreciated.

 Kazuya Nakai.

 

  • 0
    Guru 21515 points
    Hello guys,

    I forgot to inform you the IN/OUT voltage condition.

    The input voltage = 32V ~ 40V.
    The output voltage = 5V.
    The output current = 2A.

    Your advice would be very helpful for us.

    Best regards,
    Kazuya Nakai.
  • 0 in reply to Kazuya Nakai59
    TI__Intellectual 2790 points

    Hi Kazuya,

    Pls advise ctm to try adding a small cap parallel with the low side of the feedback divider resistor (Rfbb). The cap value is quite depending on the configurations of the circuit (for 10kohm Rfbb, usually a 100pF~500pF cap is preffered for such application). It will help us analysis if you can provide the schematic and layout. Also pls provide the part number of the 1mF Cout.

    BR

    Luke