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LM5170EVM-BIDIR: EVM did not work

Egon Hirsch
Expert 3550 points
Part Number: LM5170EVM-BIDIR

Hello all,

Some time ago my office buy a DCDC(48V) demo. Recently we have test the board, now I find an issue about the test steps, could you help me check the root cause? Thank you very much!

My test steps is like this:(eg: buck mode 48V to 12V)

  1. Provide the 48V
  2. Use J17-pins 5 and 6 to enable EVM, and provide 3.3V voltage
  3. DIR use J28 to realize
  4. EN1 and EN2 use J29,J30 and J25
  5. Use ISETA, and set J17-pins 11 and 12 voltage is 1.5V
  6. Then I observe the 12 VDC voltage is 24V(Up and down fluctuations), not 12V, so I don’t know why the result is this?

 

The project is ergency, I will wait for your reply, Many thanks!

  • 0
    TI__Guru* 78340 points

    Hi Egon,

    It seems you enters OVP protection.  By giving ISETA=1.5V, you basically commend the circuit to output 60A, but your load does not sink that much current.  Then, the output voltage rises and trigger the OVP (OVPB in this case).

    To avoid this, you must set your output load in a constant voltage mode.  If you want the output voltage regulation, you should use the onboard voltage loop control, then you can set your load either CC or CR, and the output will be regulated at 14.5V.  The regulation level can be adjusted by changing the low side resistor of the output sensing resistor divider.

    Thanks,

    Youhao Xi,  Applications Engineering

  • 0 in reply to Youhao Xi
    TI__Expert 3550 points

    Thank you for your reply.  I will add our hardware connect picture. In the picture, I have connect J34,J35,J36,J37, so I think I have used “onboard voltage loop control”. You say I enter “OVP protection”, could you please tell me how can I cancel it？

    Could you please check our connect method is right or not(through the last email picture)? I think this way is helpful for solving the problem, thank you very much! I will wait for your email.

     

    Best regards

    Olaf

  • 0 in reply to Egon Hirsch
    TI__Guru* 78340 points

    Hi 

    There is a duplicating post, which I just replied.  Please refer to that thread.

    https://e2e.ti.com/support/power-management/f/196/t/828668

    Thanks,

    Youhao