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LM5176: Using LM5176 for high voltage

Shlomi Weiner
Prodigy 10 points
Part Number: LM5176
Other Parts Discussed in Thread: AMC1100

Hi All,

We want to use the LM5176 Buck-Boost Controller in High voltage application.

VIN=270V-360V

VOUT=340V

IOUT=6A

We are aware that the controller is for 60V maximum, so we plan to do some modifications (such as using high voltage drivers, etc..) so it will be suitable for our requirements.

But we haven't found a solution for connecting the current sense resistor to ISNS(–),ISNS(+) pins due to the high voltage at input/output.

Are there any suggestions for solving the issue?

Thanks. 

  • 0
    TI__Guru 58225 points

    Hello Shlomi,

    You need to make sure that the voltage on these pins is not going above the abs max rating. So I would recommend using an external current sense device and use the output signal of this to connect to the internal average current sensing.

    Best regards,
    Brigitte

  • 0
    Prodigy 10 points

    Thanks for the quick answer.

    Using an external current sense device is still an issue at this input voltage range.

    Do you have any suggestions?

    Maybe using low-side current-sensing.

    Thanks 

  • 0 in reply to Shlomi Weiner
    TI__Guru 58225 points

    Hello Shlomi,

    Please be aware that every IC takes the signal that you connect to the GND pin as reference. This means that not every IC you want to use needs to be referenced to the system GND signal. But be careful with the abs max rating of the IC on all pins, if you are referencing to another signal.

    Nevertheless, low side sensing is a possibility as well. But for the topic current sensing in general, I will forward your thread to another team as my knowledge about the available solutions TI is offering here, is limited.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Guru*** 140186 points

    Hello Shlomi,

    Look here and search the page for "current" and seven choices will be highlighted. AMC1100 is a good place to start.

    https://www.ti.com/isolation/isolated-amplifiers/products.html

    For high side, high voltage current monitoring , you need isolation otherwise the common mode will become a serious headache.

    Once you have output current signal, Brigitte can help you interface that to the LM5176