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LM5111: LM5111

daniel sargezi
Prodigy 60 points
Part Number: LM5111
Other Parts Discussed in Thread: UCC27525

Hi

I'm designing a synchronous CUK converter and I want to replace the rectifying diode with a P-channel mosfet so I will have a N-channel mosfet and a P-channel mosfet. I want to use LM5111 gate driver ic to drive the switches but based on the datasheet, this ic has been designed to independently drive two N-channel mosfets. My question is that is it possible to use this gate driver ic (LM5111) in my application? Is there any way for this gate driver ic to drive a P-channel mosfet? If so, what kind of considerations should i take into account? Furthermore, using this gate driver ic (LM5111) , is there any way to program the dead time externally? As this ic does not have a programmable dead time feature. The files attached below are the datasheet of the mosfet that i'm using and the power stage schematic.

6232.sqj570ep-1019476.pdfcuk topology 1.pdf

  • 0
    TI__Genius 13445 points

    Hello Daniel,

    Welcome to e2e and thank you for your interest in our driver, my name is Mamadou Diallo from the High Power Drivers team.

    It sounds like you are looking for a dual channel driver capable of driving both the P-ch and N-Ch FETs simultaneously. Please correct me if I am wrong! 

    Depending on your specific driver requirement, I can maybe interest in a different driver that might meet your application's needs.

    I would suggest you to consider the UCC2752x family from our low-side driver portfolio Specifically UCC27525 which has an inverting and non-inverting channel as well as a higher operating supply range 20V (vs 15V for the LM5111). I noticed on your schematic, you're operating right at the absolute maximum ratings of the device so I would suggest a low supply voltage OR selecting a driver with a wider drive voltage capability to give yourself enough head room for transients on the supply. 

    With the UCC27525, you may drive the P-ch FET with the inverting channel while the N-ch is driven with the non-inverting channel. 

    Additionally, as far as considerations while using our drivers, I have attached my app note discussing layout guidelines to help ensure best performance from our dual channel drivers. 

    In addition to that, you're currently using a series turn-on gate resistance R1 and R5 of 1-Ohms, depending on how fast you're switching, you may have to tune this value to control the rise times at the gates of the FETs. The link below discusses how to accomplish this.

    http://www.tij.co.jp/jp/lit/an/slla385/slla385.pdf

    Depending on your MCU, you could implement the dead-time on the controller to ensure sufficient margin between turn-on/off the FETs as the driver will not have a programmable dead-time feature. 

    Please let us know if you have further questions.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Prodigy 60 points

    Hi Mamadou,

    Thanks so much for your recommendation. That helped a lot.