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UCC27524: output current

kura
Genius 4840 points
Part Number: UCC27524

Our customer has a question about Absolute Maximum Ratings of output pulsed source/sink current at over 0.5us.

Do you have derating curve ?

They would like to use following MOSFET.

Ciss:6650pF

Crss:490pF

Coss:4300pF

Internal Gate resister:4.1ohms

Exteranal Gate resister:22ohms +/-5%

Drain voltage:12V +/-5%

3.3ms pulth width. 

In this case they found peak current 504mA  and rise time is estimated about 1.6us in their simulation.

They would like to know whether they can use UCC27524 or not in this case.

  • 0
    TI__Genius 13445 points

    Hello Kura, 

    Thanks for your help promoting our drivers, my name is Mamadou Diallo, I am an applications engineer in High Power Drivers group.

    I have few questions that I need to clarify in order for me to comment and provide appropriate recommendations: 

    Can you please clarify the gate drive voltage VDD? What is the total gate charge of the MOSFET? Do they have a target range for turn-on/off times of the MOSFET? What is the switching frequency? Having those details will help me approximate the required current to turn-on/off the MOSFET.

    Having said an external gate resistance of 22-Ohms will significantly reduce the gate drive current as the peak current seen at the gate will VDD / Rgate, where Rgate is the total impedance (IC internal resistance + external gate resistance + MOSFET internal resistance) on the turn-on/off paths.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    TI__Genius 13445 points

    Hello Kura,

    I have not heard from you in a while, I will therefore assume this issue is closed and mark this thread as resolved. If so, please press the green button or let us know if you have further questions by further posting on this thread.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Mastermind 9530 points

    Hi, Mamadou

    Can UCC27524 tolerate 1.6us 504mA pulse current?

    Does it conflict with the DC0.3A rating?

    Best Regards,

  • 0 in reply to Hirotsugu Kobayashi
    TI__Genius 13445 points

    Hello Hirotsugu,

    UCC27524 can source/sink up to 5A for 0.5us as a pulsed current whereas the 0.3A DC current is the continuous DC. Think of it as the average current that the driver can handle continuously without stressing the internal transistors at the driver's output stage.

    The pulsed current ratings do not conflict with the DC current ratings.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Genius 4840 points

    Mamadou-san

    I'm sorry I'm late.

    We got information you requested from customer.

    the gate drive voltage VDD:12V +/-5%

    the total gate charge of the MOSFET:Total gate charge (gate-source plus gate-drain):typ 85nC (VDD ≈ 32 V, VGS = 10 V, ID = 150 A @25C) in datasheet.

    MOSFET ON time period :3.3ms ,OFF time period :long time...

    target range for turn-on/off times of the MOSFET: <5us

    Regards,

  • 0 in reply to kura
    TI__Mastermind 23105 points

    Hello Hirotsugu,

    I work with Mamadou and will address your questions while he is out of the office.

    Based on your description the current ratings of the driver should be not a concern.

    The driver ratings are 5A peak and 0.3A DC or average. Your description of the operation timing indicates low frequency, although the frequency is not specified.

    The driver average current based on the Qg is the following: Iavg= Qg x Fsw. So with 87nC and I am going to assume on time of 3,.3ms and off time of 3.3ms just to calculate the current. Iavg=87nc x 1/6.6ms = 13.2uA.

    Since the frequency is so low the average current to drive 87nC is very small. There should be no concern for the driver current rating.

    Please confirm if this addresses your questions, or you can post additional questions on this thread.

    Regards,

  • 0 in reply to Richard Herring
    Genius 4840 points

    Richard-san

    Thank you for your reply.

    Our customer carried out a simulation.

    They would like to drive MOSFET(TPWR7904PB) using with UCC27524.

    They found 504mA 3.3ms pulse current.(In this case rise time is 1.6us)

    This exceed 0.3A(Abs MAX Rating IOUT_DC).Please give us delating curve (IOUT MAX vs TIME)  or equation.

  • 0 in reply to kura
    TI__Mastermind 23105 points

    Hello Hirotsugu,

    We do not have a published curve for current Vs time for the UCC27524 as you request.

    The pulse is 504mA and pulse width is 3.3ms is what we understand. Can you explain the load that the driver is driving? If there is a capacitive load, or MOSFET gate, the driver peak currents should only exist for the rising and falling times. Is there a low resistance from driver output to ground?

    If the driver output pulse width is 3,3ms with 1.6us rise time, and I will assume 1.6us fall time, There will be a driver peak current ~1.6us wide at the rising and falling edge. Confirm if this is the waveform. If this is the case, the average current will be very low and not a concern.

    Can you provide the minimum pulse off time, or maximum frequency of the UCC27524 operation? We still would like information that can provide average current of the driver.

    Regards,

  • 0 in reply to Richard Herring
    Genius 4840 points

    Richard-san

    Block diagram is:

    UCC27524 --- 22ohms---- TPWR7094PB-----MAGSIGN


    This function is for  status indication, when accident is detected.So off time is very long time...

    MAGSIGN website is following.

    regards,

    Kura

  • 0 in reply to kura
    TI__Genius 13445 points

    Hello Kura, 

    Thanks for the additional information.

    What tool are they using for the simulation? Can you please share details of the simulation schematic via email if possible so that I can take a look? (If yes, will send you a friend request). 

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Genius 4840 points

    Mamadou-san

    We got their schematic and simulation information.I sent you a friend request.

  • 0 in reply to kura
    TI__Genius 13445 points

    Kura-san, 

    I have sent you an email. 

    Please reply to that email with simulations schematic and results so that we can further debug.

    Thanks.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Genius 4840 points

    Mamadou-san

    I had sent you email with schematic and results.

    Please let us know your advise.

    Regards,

    Kura

  • 0 in reply to kura
    TI__Genius 13445 points

    Hello Kura, 

    Thanks for the email. 

    Please see my response on the private email thread. 

    Feel free to further post here for non-NDA content.

    Thanks.

    Regards,