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LMG1210EVM-012: Heating Issue with LMG1210

Farhan Nasir
Prodigy 50 points
Part Number: LMG1210EVM-012
Other Parts Discussed in Thread: LMG1210

Tool/software:

Hello.

I am using the LMG1210 to drive a full H- bridge, but it heats up when I apply a 5MHz PWM signal. For testing i set  supply voltages 10V DC, and the current is 500mA.I have attached the design files. Can you guide me to resolve this issue. Thanks

Best Regards.

Farhan

GATE DRIVER BOARD (21-03-2024 03-35-33).zip

  • 0
    TI__Expert 8400 points

    Hello Farhan,

    What device or devices on the board are heating up? What is the temperature?

    This device has a maximum recommended junction temperature of 125C. Is this being exceeded?

    Please try the calculator on this FAQ for the maximum switching frequency based on the driver, FETs, and Vin.

    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1025075/faq-ucc27282-how-to-calculate-the-max-operating-frequency-of-a-half-bridge-gate-driver

    Thanks,

    Walter

  • 0 in reply to Walter Zollinger
    Prodigy 50 points

    Hello Walter.

    Thanks for reply. LMG1210 IC is heating up .I don't know the exact temperature but if I can run it for few minutes its heat a lot .so I cant even touch it and current also increase continuously .Can you please once review the design file  and guide me if i did any mistake. Thanks

    Farhan

  • 0 in reply to Farhan Nasir
    TI__Expert 8400 points

    Hello Farhan,

    Are you testing the board at room temperature 25C? With a 5MHz switching frequency, the part might theoretically heat up to around 75C.

    Is the output to the FETs normal? If the thermal shutdown is triggering I suggest adding a heatsink if possible.

    I do not see anything too abnormal with the design.

    Thanks,

    Walter

  • 0 in reply to Walter Zollinger
    Prodigy 50 points

    Hello Walter.

    Thank you for your response. Yes, I am testing the circuit at room temperature. I have attached the output waveforms of the LMG1210 at the high and low output pins (pins 10 and 8).

    I have selected a maximum dead time of 20 ns. However, if you look closely at the attached figure, there is a point where both outputs are slightly high simultaneously. Could this be the cause of the heating issue?

    Secondly, right now I am testing at 10Vdc and 500mA but in real application i have to operate at 160vdc and 6A  that time there will be more heat? And while testing as long as temperature is increased the current is also increasing.

    When the thermal shutdown is triggering the device will be damaged or shutdown?

    Thanks

    Best Regards

    Farhan

  • 0 in reply to Farhan Nasir
    TI__Expert 8400 points

    Hello Farhan,

    I don't think the 160V/6A bus current should cause the overheating since that is handled by the FETs. 

    The device will progressively shut down as the temperature increases to prevent damage.

    Thanks,

    Walter

  • 0 in reply to Walter Zollinger
    TI__Expert 8400 points

    Can you increase the deadtime? The overlap might be causing an issue.

  • 0 in reply to Walter Zollinger
    Prodigy 50 points

    Hello Walter,

    Thank you for your response. I selected a maximum deadtime of 20 ns using a 20 kΩ resistor, but I'm still seeing around 3 ns of overlap. I also checked the temperature of the LMG1210, and it was around 85°C at a switching frequency of 3.2 MHz. I will test it at 5 MHz as well. Do you think this temperature is within the normal range? Can you recommend  heatsink or cooling material for Lmg1210 and GaN FETs . Thanks

    Best Regards

    Farhan

  • 0 in reply to Farhan Nasir
    TI__Expert 8400 points

    Hello Farhan,

    85C is slightly high. I estimate around ~55C for 3.2MHz but the temperature is also dependent on the board material and layout.

    There is no recommended heatsink but it would require good conduction to the mold compound. It would most likely be most effective to optimize the board layout to dissipate heat through the bottom thermal pads.

    Using a FET with a smaller gate charge will also improve the thermal performance.

    Thanks,

    Walter