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LM5170EVM-BIDIR: I can not operate in buck-mode

user5897712
Prodigy 100 points
Part Number:




























LM5118








  • 0
    TI__Guru* 78440 points
    Hi User,

    The EVM can directly be used to run in buck mode. You should remove the jumper header on J31, and do not place anything there.

    Please remove all jumper headers, and follow the following instructions (starting from the left side of the board. Not in the order of jumper numbers):

    Close the following jumpers:
    J37
    J35
    J34
    J36
    J5-2-3
    J27
    J2
    J3 (optional, it should work with or without closed for buck mode. Try to close if open does not start up the circuit)
    J8
    J29-2-3
    J28-1-2
    J25
    J1-1-2
    J4
    J12-2-3

    Then you apply the source to the 48V input, the circuit will up running.

    Thanks,
    Youhao Xi, Applications Engineering
  • 0 in reply to Youhao Xi
    TI__Guru* 78440 points
    Sorry the typo for the last on in the list. It is not J12-2-3. It is J21-2-3. Sorry for the confusion.
  • 0 in reply to Youhao Xi
    Prodigy 100 points
    Dear Youhao,

    Thank you quickly response and advise.
    I was relieved that the EVM recognition was right.

    And, I changed the setting of the jumper and confirmed the operation.
    However, the secondary side will not be output unchanged.
    * I confirmed both open and short circuit of J3
    *J12-2,3 -> J21-2-3 changed
    It can not be confirmed that + 10V is occurring.

    By the way, there is an LED (BUCK-MODE: D12) indicating the operation mode.
    I thought that this LED will also be lit by mode selection, but it does not light up.
    (Is it because + 10V is not output ...)

    Is there any place I would like to check other waveforms?

    Best Regards,
  • 0 in reply to user5897712
    TI__Guru* 78440 points

    Please take a photo picture of your circuit and I would like to see if all jumpers are correctly placed.

  • 0 in reply to Youhao Xi
    Prodigy 100 points

    Dear Youhao,

    Please see atacched.

    I do not have a jumper connector, so I connect with a lead wire.

    Best Regards,

    Side-A

    Side-B

  • 0 in reply to user5897712
    Prodigy 100 points
    I connected the jumper with a circuit diagram, and confirmed it myself.

    J31 was that nothing was connected, but I have a question.
    J1 (VIN) is supplied with 48V (1-2 short),
    but R4 (100k) and R6 (49.9k) are not mounted,
    this is UVLO (10pin) of the LM 5170 open?
    And, I thought that the bias supply block is not working too.
    Even if 2-3 of J21 (AUX BIAS) is short, R43 and R44 are not mounted.

    However, even if R4 and R6 are mounted, the rated voltage exceeds the rating of 7V at this dividing ratio at 48V input.
    (It will be just right voltage if taken from the secondary side)
    Is it OK if I input voltage at which LM5170 becomes HI level to J17(5 pin)?

    Thanks your continued support, please check the jumper settings.

    Best Regards,
  • 0 in reply to user5897712
    TI__Guru* 78440 points
    Don't worry UVLO voltage now because R4 or 100k will limit the current to not damage the UVLO pin. In your final product, you can reselect the resistor dividers to reduce the max UVLO voltage to below 7V.

    R43-44 are not supposed to be installed on the EVM, and this should not prevent the circuit from operating.

    Using R4 simplify your setup. With J1 jumper open, you will have to supply a 3.3V dc signal to J17-5. Do not use J31.

    Once 48V is supplies, the 10V, 3.3V and 5V rail should be established. If not, the problem is either in the UVLO signal or the bias supplies.

    Thanks,
    Youhao
  • 0 in reply to Youhao Xi
    Prodigy 100 points
    Dear Youhao,

    Thanks your polite explanation.
    Was my jumper setting OK?

    Once again, + 10V, + 5V, + 3.3V will not be output on the connection of the above picture.
    Is it a breakdown of EVM?


    Best Regards,
  • 0 in reply to Youhao Xi
    Prodigy 100 points
    Dear Youhao,

    I removed J1, J4, J21 and checked with external power supply.
    J4-2: External power supply input + 10 V
    J17-5(EN): input + 5V from external power supply used LDO

    U3, U4 is working OK (5V, 3.3V is outputted)
    And, output of the secondary side was confirmed in Buck-Mode.
    I was able to confirm the lighting of the yellow LED for the first time! !

    I think that U5 is not working,
    Is there a possibility that it was destroyed with the jumper setting presented first?
    If not, I will contact the vendor.

    Best Regards,
  • 0 in reply to Youhao Xi
    Prodigy 100 points
    Dear Youhao,

    I'm sorry to have posted so many times.
    I was able to confirm that it works normally.

    I changed J29 from 2-3 (disable) to 1-2 (enable).
    Also, we changed the power supply turning on order to HV first, then external +10V(include EN signal) according to user's manual.
    I was not able to follow the user's manual.

    I will buy two more sheets and finally check with 6 phases.
    By using this board as a slave, I want to make it operate without external power supply.

    Moreover, I think that I will ask you with multiphase setting, but thank you in advance.
    Best regards and please have a good year.
  • 0 in reply to user5897712
    Prodigy 100 points

    Dear YouHao,

    Refer to this thread,
    https://e2e.ti.com/support/power-management/f/196/t/675889?tisearch=e2e-sitesearch&keymatch=LM5170EVM
    There was such a description.

    Note that, to use the onboard bias supply,
    you need to close J21-Pin2-3 (the right side labeled 48) when your source is on the 48V-port.
    You also need to separately pull up the the UVLO pin
    (J17-Pin5, labeled EN, but not the one next to the label, but the other pin on the same column)
    to >2.4V, to start the operation.
    Pin 6 and other pins on the same row of J17 are GND pins.
    This is the master enable and must need an external pull up on this EVM.

    With reference to this, entering 3.3 V to J17 - 5 worked correctly!
    I finally understood that this power supply is necessary to operate the EVM.
    I apologize for the trouble.

    I'm going to set up 4-phases using 2-EVMs.
    I would like to ask you again, but thank you.
    Best Regards,