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WEBENCH® Tools/LM5176: What value of income current to VIN pin is normal during the operating mode?

Andrey Yakimov
Prodigy 190 points
Part Number: LM5176

Tool/software: WEBENCH® Design Tools

Hi Team,

I'm developing lead battery and supercapacitor charging device based on LM5176.

9-15V VIN   …..  0-15V 9A OUT CCM - mode; DITHERING - disable; NO BIAS supply; Frequency 250 KHz.

If BIAS supply is not connected, LM5176 takes power from VIN pin. I don't use the BIAS supply.

I can not find any information what value of income current to VIN pin is normal during the operating mode.

My part takes approx. 80 mA. Is it normal?

Where can I get this information?

Thanks!

  • 0
    TI__Mastermind 21720 points

    Andrey,

    The LM5176 will draw about 2mA ( VIN operating current spec) if the device is not switching from the VIN pin. If the MOSFETs are switching than more current will be drawn from the VIN pin. This current can be estimated by the following equation (assuming the BIAS pin is not used)

    IIN = VCC*Qg*fsw+IINoperation

    VCC is the VCC rail voltage

    Qg is the sum of all the switching MOSFETs (This is mode dependent)

    fsw is the switching frequency.

    IINoperation is the 2mA specified in the datasheet.

    80mA  seems a little high. are you just measuring the VIN pin or are you including the UVLO divider and other external circuits in the measurement?

    -Garrett

  • 0 in reply to Garrett Roecker
    Prodigy 190 points

    Garrett,

    Thank you very much for detailed answer.

    I used MOSFETs in pairs to make my device more robust.

    Now I removed half and only 4 MOSFETs remains.

    Income VIN current now is 40 mA, but it doesn't depend of mode.

    Best Regards,

    Andrey