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LMG3422R030: The continuous current flowing through the drain and source of LMG3422

haricky yu
Prodigy 40 points
Part Number: LMG3422R030

Hello everyone

In the following figure, the current that LMG3422 can withstand is tested. In the following figure, the power supply is 48V, and the inductor connected to 3.2ohm in series is connected to the drain of LMG3422. The control signal is given by the function generator with a period of 10ms and a 5V pulse signal with a duty cycle of 1%, whose high level time is only 100us. After the power is turned on, the smell of burnt plastic is smelled. After the power is turned off, the 12V input pin is measured and no short circuit occurs. After the power is turned on, the voltage at both ends of the C36 is -4.7V. The Id current in the data manual is 55A. Why is LMG3422 damaged when the duration of the current given by me is 14.5A for 1us? Under what conditions will continuous current not burn this chip?

best，

haricky

  • 0
    TI__Expert 7435 points

    Hi Haricky,

    What is the thermal setup for this test? The device datasheet has an Abs. Max ID(RMS) of 55A, however you still have to dissipate the heat from the device to keep the junction temp below the data sheet specified Abs. Max operating junction temp of 150C.

    Best,

    Kyle

  • 0 in reply to Kyle Wolf
    Prodigy 40 points

    Hi Kyle

    As mentioned in the data manual of the LMG3422 chip, there are corresponding protection mechanisms in the chip for short circuit, overcurrent, overtemperature, undervoltage, etc. Once the above errors occur, the control signal of the chip port will not be effective until the error disappears. The GaN power IC integrates overcurrent protection (OCP), short-circuit protection (SCP), overtemperatureprotection (OTP) and undervoltage lockout (UVLO)”“The overcurrent protection (OCP) circuit monitors drain current and compares that current signal with an internally set limit. Upon detection of the overcurrent, the LMG342xR030 conducts cycle-by-cycle overcurrent protection ”“ In this mode, the GaN device is shut off when overcurrent happens, but the overcurrent signal clears after the input PWM goes low. In the next cycle, the GaN device can turn on asnormal”，According to this information, there is no risk of damage to this chip. When the power supply is less than 200V, there is damage in the time application. Please help analyze what causes the damage, thank you

    Best，

    Haricky

  • 0 in reply to haricky yu
    TI__Expert 7435 points

    Hi Haricky,

    I've sent you an email to set a meeting to continue this conversation and the conversation in the other thread.

    Best,
    Kyle