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  • TI Thinks Resolved

UCC28180EVM-573: UCC28180 Evaluation module blows up repeatedly

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Replies: 8

Views: 813

Part Number: UCC28180EVM-573

Hello

We boguht the ucc28180evm-573 for evaluating the circuit.

But we ended with a problem, the evaluation module blown up at the power up, without any load connected to it.

I tried to investigate this further, I noticed there should be a specific power up sequence???

Apply the AC then the AUX 12V supply.

The power up process I am using now is Apply AC, then Apply AUX then BOOOOOOM

I had to repair the board by replacing the Mosfet and the dead UCC28180, repeat the process, BOOOOOM

By searching the internet, I came across this file TIDA-00776, and this module has an AUX supply already, BUT there was a switch to power up the circuit, NOT directly powered up once you apply the power.

It is clear there is some trick out there in the power up sequence.

I would love to hear from ti regarding this issue.

Thanks

  • Hello 

    Sorry to hear that you are having this issue with the UCC28180EVM. Obviously this is not meant to happen and I will try to find out what is happening.

    A normal startup sequence is for AC power to be supplied to the pfc followed by startup of an auxiliary power supply that generates bias power to the pfc controller.
    This will initiate a soft start of the pfc which then generates the high voltage DC output.
    It is also possible to first supply bias power (from say a 12V DC lab supply) to the UCC28180 and then apply AC power to the EVM. This should not cause failure of the EVM. So it should be possible to startup the EVM in any sequence.

    Do you think it is possible that you are applying DC bias, turning it off and turning it back on again ? Perhaps an intermittent connection on the 12V DC input ?
    If so this will cause failure of the EVM because the output voltage is at its set point and when you re-apply bias power the UCC28180 will go to full duty cycle which will cause an over voltage on the output, destroying the semiconductors.

    Regards

    John

  • In reply to John Griffin1:

    Hello John,

    To tell you the truth, I did that maybe once when first time testing the module.

    After that the 12V was applied all the time, then the AC was applied.

    I think also the AC was disconnected quickly and re applied,then BOOM.

    Today will try to connect a 12VDC supply, and power up at the same time.

    But I never had such thing with other controllers.

    Please advice if we can put this controller into our project and use it, we are unable to determine if this is a failure in the chip or it has specific requirements?

    Thanks

  • In reply to Micro:

    Hello Micro,
    This is what I think is happening :
    A controller that measures input voltage will go into brownout when the high voltage input drops below a set level.
    In brownout, the soft start capacitor is discharged and once the input voltage is re-applied the soft start cap starts to charge again.
    This causes a gradual increase in gate drive pulse width.
    But with the UCC28180 if the high voltage input drops out the gate drive goes to max duty cycle because the input voltage is not being monitored and all the UCC28180 see is that VOUT is low.
    Once the input voltage comes back online, the converter will go to an over voltage condition because of the slow loop response of the pfc.
    This is causing the catastrophes you are witnessing.
    If your design is likely to see large brownout conditions then I recommend that you use the UCC28019A or use an external brownout circuit with the UCC28180. Also some other multi pin pfc controllers have brownout and some have a non-linear error amplifier which has low gain for large error signals followed by high gain for small deviations in error signals. TI calls this Enhanced Dynamic Response (EDR) .
    I recommend that you investigate the UCC28019A for your application.
    Regards
    John
  • In reply to John Griffin1:

    Hi John,

    Its not that my application see large brown out, but its is common for the application to get the AC line disconnected and re connected quickly, this will happen for sure.

    But still one test to go today, I will feed the UCC28180 from an AUX supply that will power up at the same time.

    Any brownout circuits to suggest?


    Regarding the UCC28019A, 3 years ago I had very nice results with that chip, but there was an inductor noise. connect / disconnect from no load to full load, no issues at all, even at 5A output @ 385VDC @ 115VAC input. facing 1200W load at power up even no problems.

    It was very nice chip except that inductor noise.

    Will update you on this.

  • In reply to Micro:

    0243.EPGI Discrete brownout function of UCC28180.pdfHello Micro,

    Attached is a brownout circuit that was designed for use with the UCC28180.

    The inductor noise issue with the UCC28019A is probably not related to the UCC28019A but something to do with the winding or manufacture of the inductor itself.

    I really cant say but audible noise from pfc circuits can happen with any controller and is more related to construction of the power supply than the control architecture.

    Regards

    John

  • In reply to John Griffin1:

    Hi John,

    Last update for the UCC28180

    I had no success to make it working, it keeps blowing up, even when I connect it to its own AUX supply that powers up at the same time.

    I have just rebuilt the UCC28019 PFC circuit, everything is working fine, load the PFC full then power up, no issues at all.

    I only still facing 1 major problem with that chip, witch is the output over voltage issue.

    In idel i have 409VDC, load the PFC with 300W still 409VDC, no problems at all.

    Remove the load, voltage goes to 426VDC then goes back to 409VDC witch makes my regulated SMPS to become unstable at that moment causing its output to increase by 2VDC then goes back to its normal output voltage.

    I will appreciate your help if you can take a look at the attached paper, my problem is shown in page 6, I only need help on designing that circuit using the TL431 to tighten the voltage regulation.

    Your help will really solve my issue with this chip, as it is robust and I am welling to use it into the design.

    Kind regards

    8562.Optimizing the UCC28019A to Avoid Audible Noise.pdf

  • In reply to Micro:

    Hello Micro,

    I am glad that you are making some progress with your issues and I will help with utilizing the SLUA688 document you attached.

    But before you  try this you should realize that your overshoot is only 4% and the best way to reduce this is to increase the output capacitance.

    The OVP for the UCC28019 is set at 5% so your circuit is probably not going into OVP anyway.

    My opinion is that the issue is with your regulated DCDC converter.

    It needs to be able to handle a small 4% variation in input voltage.

    The schematic is attached above and the idea behind it is very simple.

    You set the voltage divider from Vout ( this is 409V in your application ) so that the voltage on VSENSE is 5V.

    If the upper resistor is 1MOhm then the sum of the lower two resistors will be 12.37kOhms.

    Then you set one of these lower resistors at say 5.6k Ohms. If you know the voltage you want the circuit to trip at then you calculate the final resistor based on getting 2.51V with the overvoltage on VOUT.

    Regards

    John

  • In reply to John Griffin1:

    Hello Micro,
    I am going to close this thread since there has not been any new posts in 3 weeks.
    Please open a new thread if you have any further queries.
    Regards
    John

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