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TIDA-01573: The measured output rising edge is rather slow

Fred Zheng
Prodigy 90 points
Part Number: TIDA-01573
Other Parts Discussed in Thread: LMG1020

Hi,

I am using the TIDA-01573 board. But the measured output rising edge is rather slow. What is the problem? Is the FET damaged? Or my measurement method is wrong?

The 1st pic is Vg waveform. The second pic is Vk waveform.

Thank you for your help!

  • 0
    TI__Genius 12990 points

    Hi Fred,

    Thanks for asking about TIDA-01573.

    Your Vg looks like LMG1020 output is switching ok with fast rise/fall time so you measurement method look fine. However the cathode waveform K has a fast fall time to turn on but very slow 100ns rise time to turn off. This issue appears to be either a damaged resistor(s) from the dummy load (which is the 4 parallel resistors R5-R8) if its being used or a damaged FET due to using a large switching frequency and duty-cycle combination.

    What is the resistance of your resistor dummy load? It should be 1ohm, if its more then replace the dummy load with four 4ohm resistors. If you are using the EVM with a laser diode, you have to remove the resistor dummy load before testing. If the resistor dummy load correctly reads 1ohm and the issue still exists, does replacing the FET fix the issue? 

    thanks,

  • 0 in reply to Jeffrey Mueller
    TI__Genius 12990 points
    Hi Fred,

    Just checking to see if this helped with your issue, please let me know if you have any questions.

    thanks,