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LM5145-Q1: Issue with LM5145-Q1 buck Switching regulator IC

Venu Gopal
Prodigy 90 points
Part Number: LM5145-Q1
Other Parts Discussed in Thread: LM5145

Good evening!

This question is regarding load test of the LM5145 Buck regulator IC.

I have designed my circuit for 24V output voltage and 30A output current. for the load purpose i have connected 10 number of 168-ohm resistors in parallel to the buck converter output it should draw a current of 1.42A but the IC gone instead of giving output current. we have checked by connecting electronic load which can be used as power supply as well as load at that time also the IC was gone. can you please let me know what the reason behind this IC failure and a possible solution for the same problem.

One more issue with the same circuit was it is taking input but not giving gate pulse to the MOSFET gate pin. we thought that was a assembly issue since it was a QFN package IC. We bought solder paste and we did the assembly, and we did lead free soldering also in both cases we are facing the same challenge that gate pulse is not coming from the LM5145 IC.  can you please let me know what the reason behind this IC failure and a possible solution for the same problem.

kindly provide answer to my queries.

Thanks in advance.

  • 0
    TI__Mastermind 40160 points

    Hello Venu,

    Can you check VCC if this comes up? It maybe the IC got damaged and recommend replacing and retrying.  I hope the issue, if you are still facing problems, then please reopen this thread, please fil out the calculator sheet to help me understand your requirements, link below, also please send me your schematic you have implemented to check.  Thanks.

    LM5145DESIGN-CALC Calculation tool | TI.com

    Hope this helps,

    David.

  • 0 in reply to David Baba
    Prodigy 90 points

    good morning,

    Thank you for your prompt response, sir. in this reply I am attaching my calculations excel and schematic file for better understanding on my problem.

    Same IC have another issue that is I am mentioning below.

    I have designed my circuit for 24V output voltage and 30A output current. for the load purpose I have connected 10 number of 168-ohm resistors in parallel to the buck converter output it should draw a current of 1.42A but we lost the IC instead of getting output current. we have checked by connecting electronic load which can be used as power supply as well as load at that time also the IC was gone. can you please let me know what the reason behind this IC failure and a possible solution for the same problem.

    /resized-image/__size/320x240/__key/communityserver-discussions-components-files/196/pastedimage1708583668314v1.png

    LM5145_Calculations.xlsx

  • 0 in reply to Venu Gopal
    TI__Mastermind 40160 points

    Hello Venu,

    I checked your design, I don't see anything that stands out to me that would case failure.  How is your layout?

    Did you follow the guidance provided in the datasheet, if not, this may  be the cause of the failure.  Also do check you have installed the correct values and there are no shorts on your board.

    Layout concept based on datasheet guidlines. 

    Hope this helps,

    David.

  • 0 in reply to David Baba
    Prodigy 90 points

    Thank you for your prompt response, sir.

    I will check my layout of the PCB whether we are missing any guideline's or not. 

    kindly provide response for the below query 

    I have designed my circuit for 24V output voltage and 30A output current. for the load purpose I have connected 10 number of 168-ohm resistors in parallel to the buck converter output it should draw a current of 1.42A but we lost the IC instead of getting output current. we have checked by connecting electronic load which can be used as power supply as well as load at that time also the IC was gone. can you please let me know what the reason behind this IC failure and a possible solution for the same problem.

  • 0 in reply to Venu Gopal
    TI__Mastermind 40160 points

    Hello Venu,

    If the layout is poor and guidelines not followed, this can cause failure to the device.  instability can cause a device to fail in addition to noise causing the device to malfunction, turning on a FET when it is supposed to be off during the period is one example.  Hope this helps.

    David.

  • 0 in reply to David Baba
    Prodigy 90 points

    Thank you for your prompt response sir, can you please explain in detail about the turn of FET and gate pulse from LM5145 IC.

  • 0 in reply to Venu Gopal
    TI__Mastermind 40160 points

    Hello Venu,

    Accurately describe here under the sub heading. "Shoot-Through in Synchronous Buck Converters"

    Analyzing Power Modules (ti.com)

    Hope this helps,

    David.