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Thread: IFX007 parallelizing

  1. #1
    New Member New Member wilopaan is on a distinguished road
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    IFX007 parallelizing

    Hi all,

    I tested the IFX007 (no heatsink) with up to 20A current and it got very hot: 4W * 19K/W = 76K above ambient temperature.

    Is it possible to parallelize IFX007, also in an PWM use case?

    Thanks!
    Wilhelm

  2. #2

    Infineon Employee
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    Jing.N is on a distinguished road
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    Hi Wilheim,

    It is possible to use to parallelize IFX007T in PWM mode. Of course the power dissipation highly depends on your mission profile: Vs, I, frequency, switching time(slew rate resistance)...
    If you can provide more detailed information, I could perform some thermal simulation to figure out if the device is able to be used for applications.

    Regards,

    Jing
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

  3. #3
    New Member New Member wilopaan is on a distinguished road
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    Thanks for your reply.

    Vs = 24V
    I > 20A
    PWM-Freq=16KHz
    slew-rate: as fast as possible

    But isn't it a problem due to delay variations, because either to high-sie or the low-side is conducting?

  4. #4

    Infineon Employee
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    Since we have protection feature integrated into IFX007T, we won't have any cross current caused by the delay variations. But due to the variation the output duty cycle might be a bit different from the input duty cycle.

    I did some thermal simulation based on your mission profile and some other assumptions:

    Load to Vs
    Vs = 24V
    I = 20A
    PWM-Freq=16KHz
    Duty cycle: 50%
    slew-rate: as fast as possible
    PCB: 2s2p

    The temperature increase is roughly 90C after 10s. The switching loss is the main contributor to it. If the application keeps running afterwards, the temperature will keep increase and the device might be turned off by over temperature protection feature.
    If would be quite helpful if lower frequency is acceptable for your application.
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

  5. #5
    New Member New Member wilopaan is on a distinguished road
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    If I use two IFX007T for one half-bridge, I have to connect Vs, Gnd and Ouput. If the switching delay in one IFX007T is slightly different (say 0.9us) from the other IFX007T (say 1us), we have a shoot-through from one FET from one IFX to the other FET from the other IFX. This is a matter of how large is the variation in switching delay in the production process of the different IFX.

    Well, the PWM-frequency can be dynamically lowered down to 1KHz. Would you please simulated the switching losses in this case too?.

    Thanx!

  6. #6

    Infineon Employee
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    I did thermal simulation for the new mission profile below:

    Load to Vs
    Vs = 24V
    I = 20A
    PWM-Freq=1KHz
    Duty cycle: 50%
    slew-rate: as fast as possible
    ambient temperature: 25C
    PCB: 2s2p

    In this case, the temperature increase is only 59C after 500 seconds, and the temperature curve is going flat afterwards. Therefore it should be ok for your application.
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

  7. #7
    New Member New Member wilopaan is on a distinguished road
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    Did you consider my quote belonging the parallelizing in general?

    From above:

    If I use two IFX007T for one half-bridge, I have to connect Vs, Gnd and Ouput. If the switching delay in one IFX007T is slightly different (say 0.9us) from the other IFX007T (say 1us), we have a shoot-through from one FET from one IFX to the other FET from the other IFX. This is a matter of how large is the variation in switching delay in the production process of the different IFX.

    Do you still see no problems?

    Thanx!

  8. #8

    Infineon Employee
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    I thought you might use more than one IFX007T on one PCB. Sorry for my misunderstanding. Now I understood your point.

    We don't recommend our customers to use two devices for one half bridge. Due to the variation of the delay time, we might have some current flow through HS of one device to the LS of the other.

    For the simulation, I only take one device into account.
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

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