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LM5170-Q1: how to check the chip is on the oscillator frequency?

wenwu wang
Prodigy 70 points
Part Number: LM5170-Q1
Other Parts Discussed in Thread: LM5170

I seted the the frequency=100K,  but i can not measure the freuency?

  • 0
    TI__Genius 11215 points

    Hello, 

    Thanks for reaching out. Do you want to see if you converter is really switching at 100kHz? In that case, you might check the switch nodes or the gate of you MOSFETs. Let ne know if further help is needed. 

    Kind regards, 

    EM 

  • 0
    Prodigy 70 points

    Hi,EM

    Thanks for yout help. I can get the 100kHz of the gate pin . but there  is not right issue?

     when apply DC 48V to the HV port, the LV port will get the 20V and i try to adjust the voltage of ISETA pin

    from 0~1.25v, the LV port voltage can not change, what can i do next?

     

    HV

  • 0 in reply to wenwu wang
    Prodigy 70 points

    Hi,EM

    Thanks for yout help. I can get the 100kHz of the gate pin . but there  is not right issue?

     when apply DC 48V to the HV port, the LV port will get the 20V and i try to adjust the voltage of ISETA pin

    from 0~1.25v, the LV port voltage can not change, if LV is in the OVP mode?

     also we check the wave  of the HO2 wave,  this is different with the  datasheet.

     

    /resized-image/__size/320x240/__key/communityserver-discussions-components-files/196/pastedimage1638789158391v1.png

    ...

  • 0 in reply to wenwu wang
    TI__Genius 11215 points

    Hello, 

    Thanks for your feedback. Let me reach out for the expert of this device for further support, we will come back to you as soon as possible. 

    Kind regards,
    EM

  • 0 in reply to EM
    TI__Guru* 78630 points

    Hi Wenwu Wang,

    Please share your complete schematic so we can see how have you set up your circuit and how you close the control loops.

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    Prodigy 70 points

    PWR_V0.1.pdf 

    This is complete sch,  there are a few question need to help:

    1. when power on the LM5170 board , the LV port voltage  about is 20v, can i set  the LV voltage  to 14.8v? 

    2. The HO1/2 wave is not pwm wave and different with the  datasheet, if it is ok?

    3. Can set  the ovpA  protect voltage to 15v, Now the LM5170  chip very easy  damage by LV high voltage.

    4. If the LM5170  have the OCP protect?

  • 0 in reply to wenwu wang
    TI__Expert 7450 points

    Hi Wenwu,

    I think we have your other post question covered here so I'll just close the other one.

    For your questions, I'll need a few more information.

    1. Could you please help me identify the ISETA connection on the schematic? It is tied to "FB" but I cannot find FB elsewhere.

    2. As mentioned in the other post, could you please show where you probe (or which two points you probe) on the board for this waveform? You can mark them on the schematic as well.

    3. What is the LV high voltage?

    4. LM5170 has the cycle-by-cycle current limit protection. You can refer to the datasheet for more details.

    Thanks,

    Yinsong