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LM5170EVM-BIDIR: LM5170EVM-BIDIR:

Kartavya Agarwal
Intellectual 500 points
Part Number: LM5170EVM-BIDIR
Other Parts Discussed in Thread: LM5170

Hi,

I am trying to use the V48_SN and V12_SN pins on header J17 of the LM5170 EVM to measure the voltage on the 48VDC and 12VDC ports, respectively.

I am seeing a voltage signal of less than 2V on the V12_SN pin when the EVM is configured for buck mode operation, DC supply on 48VDC port is 48V, and measured voltage on 12VDC port is approximately 20V.

Could you please help me out with the conversion equation that needs to be applied to voltage measured at V12_SN to map it to the actual voltage being observed on 12VDC port? I have looked through the datasheet and EVM user guide but I'm unable find this information.

Sincerely,
Kartavya Agarwal.

  • 0
    TI__Guru 68495 points

    Hi Kartavya,

    You can get the ratio by V48 / V(OVPA), and V12 / V(OVPB).  These two pins will vary linearly with V48 and V12, respectively. 

    Specifically, as mentioned in the datasheet, there are two internal pull-up resistors.  3Meg from VIN to OVPA, and 1Meg from CSB1 to OVPB.   These internal resistor and the external OVPA and OVPB forms a the resistor dividers, and they can be used as the V48 and V12 rail voltage.

    Hope this clarifies.

    Thanks,

    Youhao Xi, Applications Engineering.