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Recent content by Bjtpower_magic

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    Magnetics- Safe operating temperature

    Hi, Someone has designed transformer 10 years ago and left company and i am poor at Magnetics, Can you please help? Specifications: Flyback Converter Input Voltage range: 20-28VDC Output Voltage: 5VDC Output Current: 8A Switching Frequency: 130KHZ What is safe temperature to magnetics to...
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    MOSFET parasitic capacitance and charge

    Yes.. Output Load. Secondary of Flyback. 1. Loaded with 10% of full load. 2. Leaded with 50% of full load. 1691159538 VGS at 1A VDS at 1A
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    MOSFET parasitic capacitance and charge

    Hi, Is there any relation of Load vs gate drive voltage. I have observed that Vgate_Plateu voltage changes with load. Gate drive with 10% load Gate drive with 50% load:
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    MOSFET parasitic capacitance and charge

    Hi All, Thanks for your responses. I hope this post will help everyone who would like to understand Mosfet and Gate drives, it has helped me a lot. Thanks once again all of you to have a great discussion, Keep discussing.. Keep helping.
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    MOSFET parasitic capacitance and charge

    Captured with more accurate oscilloscope Offtime Ontime: 1690363995 Hi, I mean is there any criteria from Datasheet of Thumb rule for Plateau time? What is acceptable range? how to derive it? Sorry for asking too much questions but honestly i am trying to understand.
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    MOSFET parasitic capacitance and charge

    Hi, Gate resistor is 4.7R/0.25W. Turn off did not capture yet, but will share once get. How do you know 70nS is acceptable?
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    MOSFET parasitic capacitance and charge

    Hi, Do we need to relate this with Mosfet Dataseet? How one will know that everything is well? Mosfet is turning right? Lets say if i reduced/increased gate resistance? still i will see similar graph of VGS?
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    MOSFET parasitic capacitance and charge

    Hi, I think it has already charged Cgs, during miller plateu where Gate voltage and Drain voltage about to equal or less than Gate voltage then Cgd comes into play and during that time, it charge Cgd. I wonder is this behavior acceptable as shown in Scope image? How one can be sure is it fine...
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    MOSFET parasitic capacitance and charge

    Hi, Now i have done some practical experiment and have some results. We have UCC3809 and Mosfet IRFZ44. VDD for UCC3809:10.6V Drain Voltage or Input Voltage: 24V Frequency: 130KHZ Condition: No Load. I cannot understand this is right behavior? This waveform captured across Gate to Source...
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    What is Mosfet static characteristics and Dynamic characteristics

    Hi, I have been tasked to perform Static and Dynamic power analysis of Mosfet for Flyback converter (Allready designed ) And we have found mosfet closer to IRF60B217 (IRF60B217 Datasheet Link) but we would like to do Static and Dynamic power analysis. I have never done this kind of analysis...
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    MOSFET parasitic capacitance and charge

    Hi Klaus, Thanks for detail explanation. Now its pretty clear and good informative for others as well. I have last doubts. I see you considered Fall time and not Rise time Rise time for IRZ44=97nS Rise time for IRZ44=37nS I have rearranged equations: IRFZ44: Miller charge (Q_GD during t_f) =...
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    MOSFET parasitic capacitance and charge

    Hi, Which tr and tf are you cosnidering. Gate driver has different values and Mosfet has different values. Which needs to consider? Also you only considered Qgd and not Qgs which is also important, What do you think? My Switching frequency is 135KHZ, Total cycle time=7.4uS, Max Turn on Time...
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    MOSFET parasitic capacitance and charge

    For Gate drive calculations for Particular mosfet. I see that, IRF60B217 is good candidate over IRFZ44VPbF RDS ON is better, Gate charge is lower but i have concern on Rise time. I want to keep UCC3809 which has source current of 0.4A Can you please help me with Gate drive current required...
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    MOSFET parasitic capacitance and charge

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    MOSFET parasitic capacitance and charge

    Hi, Thanks for your reply. But if you look into Mosfet Driver UCC3809, capable of provide 0.4A source current and i feel it cant drive IRF60B217. FOR IRFZ44VPbF From Datasheet: Total Gate Charge: 67nC Total Rise Time: 97nS I_Peak=dQ/dT=67nC/97nS=0.69A FOR IRF60B217 From Datasheet: Total Gate...
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