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Have I damaged my EVAL6498L board?

three-phase

Hi All,

 

I have been moving on to testing the double pulse function within the AFG31052. To do this I purchased an EVAL6498LEVAL6498L board as used in the application note from Tektronix.

 

Below is the scribbled out setup I created.

 

image

 

I have successfully loaded the double pulse software onto the AFG31052 and I can capture the pulse output from it on an oscilloscope. I can trace that pulse pattern onto pin 2 of the L6498L MOSFET driver. From the data sheet on the board, I believe the pulse output to the MOSFET should then come out on pin 6 of the chip onto resistor R7.

 

Resistor R7 I soldered in, the 320N20N MOSFET I am using suggests a value of 25 Ohms. As that seemed a little hard to find, I soldered in a 22 Ohm resistor. Initially, I also soldered in R4 to the top MOSFET, but reading the application sheet a few more times, this is not used, and I should have shorted out the gate and source of the top MOSFET. Is the upper MOSFET required at all, can I just short source to drain?

 

I removed R4 and shorted gate to source, but still have no pulse train to R7 and the second MOSFET.

 

Is this looking like I have damaged the board? I have seen that the L6498L chip can be purchased separately, but I am not sure I will be able to solder that in place on the board, so will need to get a new board, but just wanted to make sure that there isn't something else I can check before I purchase a new board.

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  • Hi Donald.

     

    I think (please check the datasheet in case I've made a mistake, I don't want to damage things. I was looking at the datasheet here: https://www.st.com/resource/en/datasheet/l6498.pdf ), doesn't VCC need to be be minimum 10V?

    On your sketch, it is marked connected to 5V Rigol (guessing that's a 5V PSU).

    The IC has protection according to the datasheet, that likely won't allow it to operate at a low voltage, to protect the MOSFETs from not fully turning on.

    If that's the case that it is being powered from too low a voltage, then your board is likely fine due to that cut-out, and it should work fine then with a higher voltage.

  • in reply to shabaz

    Many thanks , I missed the typical settings section and just looked at the minimum / maximum settings and just selected 5V supply due to the TTL compatibility.

     

    The pulses are now coming out of the chip onto R6, but MOSFETs are still not turning on correctly. I think part of the issue is that my power supply is only 3A and there is a lot of voltage instability during the switching.

     

    Kind regards.

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  • in reply to shabaz

    Many thanks , I missed the typical settings section and just looked at the minimum / maximum settings and just selected 5V supply due to the TTL compatibility.

     

    The pulses are now coming out of the chip onto R6, but MOSFETs are still not turning on correctly. I think part of the issue is that my power supply is only 3A and there is a lot of voltage instability during the switching.

     

    Kind regards.

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