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LM5176: LM5176 IC pin BOOT1 and SW damaged

Rock Shao
Expert 2810 points
Part Number: LM5176

Dears,

LM5176 is used in DC to DC 40W, the specifications are as follows
DC input: 12V ~ 50V
DC output: 16V / 2.5A

At present, when the IC is controlled in the buck-boost region, the LM5176 will be damaged. Please help confirm the problem. The description is as follows:
1. When DC input 12V (boost mode), output 16V/2.5A works normally.
2. When DC input 24V (Buck mode), output 16V/2.5A works normally.
3. When DC input is between 15V~19V (buck-boost region), LM5176 will be damaged (Pin26 BOOT1 and Pin28 SW1 low impedance)

I have checked the waveforms in the buck-boost mode, the Vgs was stable, and also choose the low Vth and Qg MOSFET, but the IC will be damaged after working for a period of time.

Has TI ever encountered this similar problem? Is there a solution?

Thanks and regards.

  • 0
    TI__Genius 11215 points

    Hello, 

    Thanks for reaching out. Unfortunately, the quality of the schematic you shared is very blurry, would you mind to share it again (maybe as a pdf file)? What kind of damage did you see at those two pins? Did you also see any malfunction of the converter as well in buck-boost mode? I'm looking forward to hearing back from you. 

    Kind regards, 
    EM

  • 0 in reply to EM
    Expert 2810 points

    Hi EN,

    Please see the schematic.

    When DC input is between 15V~19V (buck-boost region), LM5176 will be damaged (Pin26 BOOT1 and Pin28 SW1 low impedance)

    I have checked the waveforms in the buck-boost mode, the Vgs was stable, and also choose the low Vth and Qg MOSFET, but the IC will be damaged after working for a period of time, but can not get any waveforms.

  • 0 in reply to Rock Shao
    TI__Genius 11215 points

    Hello, 

    Thanks for your feedback. Is the high side MOSFET being damaged as well? What kind of damage do you see on the IC and how do you check this damage? How long can the IC work in buck boost mode before getting damaged? Is there anything overheating on the board? Can you please try to provide the waveforms so that we can check how the controller is behaving? 

    Kind regards, 
    EM