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31 Threads found on Mosfet Push Pull
What's the duty cycle of your rectangular 500Hz signal? Seems like the bootstrap capacitor doesn't have enough time (or enough current) to charge. What's the voltage across the bootstrap capacitor? It has a high ripple, I suppose. You should try a faster bootstrap diode, a decoupling capacitor across Vcc and a smaller gate series resistor. [COLO
With "snubber" you mean a diode parallel to mosfet drain-source? It doesn't serve a purpose in a flyback circuit ("single mosfet driving a transformer").
Hello dear edaboard members ; I'm really tired of getting the same error from proteus :( I have 48 to 12 V dc-dc converter pre-design(not completed to apply in real life) with UC2525 PWM regulator chip. My problem is when i am trying to drive to mosfet gates(IRFZ44N) PWM-A(pin-11) is nearly correct but PWM-B(pin-14) is about to gnd.(some 1V peak
Need a Heavy Duty Buck Converter with Negative Common. Conditions and Ratings: Input: 18 ~ 30V DC Output: 12.5V / 10A Continuous. Run time: 24hrs at 10A. Cooling system: None / Air Cooling. Input and Output Ground is common. N-Channel mosfet. This was the conditions. I tried with push-pull type, Single Inductor Buck (...)
At least this problems: - RCD not working (wrong D4 polarity) - very slow mosfet turn-off due to bad gate driver circuit. Should use push-pull transistor buffer. It's also unclear if the transformer has right winding polarity for flyback operation.
Do you mean that the external diode is not needed? Yes, very clearly. In addition, you can ask if the diode is needed at all. But that's a theoretical question because it's present in any mosfet. The dominant problem of the transformer push-pull converter is overvoltage after switch-off, caused by the transformer leakage inductan
Your circuit has several issues. Worst of all, 35 V gate voltage will immediately kill the mosfet. You need a voltage limiting means for the gate voltage. Secondly, the relative large load resistor R1 will only slowly discharge the gate capacitance. For fast switching a lower resistance or preferably a push-pull driver circuit is (...)
The oscillation shown in post #6 has rather low energy, transformer main inductance with off-state mosfet output capacitance. The voltage is safely clamped by the FET substrate diodes, no risk to damage anything.
Once a mosfet is switched on, it will not switch off again even if the voltage is removed, because the parasitic capacitance between gate and source (1nF to 5nF typical) will store charge and will maintain the gate-source voltage even when the signal is removed. To remove this charge quickly, a resistor is required in parallel with this capacitor.
You didn't yet mention 8051. It has open drain outputs with weak pull-ups instead of regular push-pull outputs. As a simple solution, you can place strong (e.g. 1k) pull-ups. If you also want safe reset behaviour, an inverting driver (like 74HC04) between 8051 and mosfet is suggested.
Since the two transistors in a push-pull amplifier are in series the current through both will be the same as long as the output is set to 0V output bias (or the output is capacitively coupled). The mosfet resistance to current flow is determined by the gate to source bias voltage on each transistor.
I'm try to run mosfet with high frequency..30 khz..10 duty cycle. i got turn off switching in mickro second but when i read data sheet is about nano second. Is it normal?, or is anybody have idea to reduce this turn off switching90037
First of all check how much current is required for the FAN. Then choose a mosfet as a switch controlled by the microcontroller to give the power supply to the fan. Sometimes the mosfet might need an external driver, because of higher threshold voltage and if isolation is needed between mosfet and uC since mosfet might be (...)
Hi ı am both newbie in this forum and power electronics. I have a 1kVA UPS project and ı have some issues about making the DC bus voltage stable 311VDC for getting 220VAC in h-bridge across the mosfets. My inverter has approx. 10-11 volts PWM output. I have 36VDC from 3 lead acid battery and ı have to boost the voltage about 311VDC i
Hi, Sorry if the questions sound stupid!! I'm just confused and need help! I'm working on a power inverter project, im using two Power mosfets 'FQP30N06', at 100KHz PWM, do I need a gate driver to control the FETs or connecting the gate directly to the PWM pin output from STM32F4 is enough? I tried connecting them directly from the pinout, t
I can't seem to find anything on the topic of mounting high power mosfets directly to hunks of metal to carry a bunch of current. How is such a thing done and does anyone have a link to someplace I could look at to get a good idea of the property way to connect the drain, sink, and gate if I wanted to use metal bars to carry power. Thanks. Edit:
You can measure the primary leakage inductances on your push pull transformer, you can assume the dominant cap will be the mosfet, use a snubber cap 5-10x this value. calculate R from 0.5 x SQRT(L/C), if you have very high leakage and/or reflected energy from the secondary there are other ways to work out the RC based on Ipk at (...)
Hello, Are you working on a push-pull converter with center-tapped transformer? When you are using mosfets, the magnetizing current will find its way through the body diode of the mosfet that was off. Depending on the leakage inductance of your two windings that form the center-tapped primary, you may need a (...)
... It should deliver as much power as possible to a 20 ohm load. Therefore, I am trying to make the output impedance as near to 20 ohm as possible. No, to achieve this, Rout ≪ 20Ω ! Thus, obviously I should use a common drain mosfet. However, the problem is output impedance of a common drain mos
Hi everyone,can anyone please explain to me how the circuit in the above link works?How the mosfet push pull driver works in the circuit?and what is the purpose of putting a capacitor at the gate of the P-channel mosfet.(main concern is to understand how the push pull driver opereate and the (...)
By increasing the gap the inductance wil go down. The inductor current will increase but, as previously mentioned, this is a technique used to avoid saturation. Your mosfet will heat more, leakage will increase (bad regulation) and the EMC will increase.
Check ringing frequency .refer to Unitrode app note on snubber design you can calculate values of res. & cap. First check leakage inductance of your transformer. Increase value of gate resistor to reduce rise time / fall time. This will also reduce ringing. But increase heating in mosfet so don't increase beyond 33E/47E
Hello guys, I am driving DC motor 12volts 6Amp via mosfets with Heat sink & cooling fan, the problem is that when I decrease the duty cycle below 20% the mosfets become very very hot (some times burns out), It works fine above 50% duty cycle runs motor under normal temperature. How I can protect mosfets from burning??
Hi Friends I am doing my project on inverter. So I want gate driver circuit for mosfet and at the same time circuit diagram of multilevel inverter
How to invert 3Vdc to 115 Vac using mosfet circuit, send me the circuit if anybody possible to support . Also is it reliable for some long time usage for their components:idea::D
the way you have biased the circuit is right only also the mosfet is stable even through temperature changes.... i think you have to be careful in the selection of resistors and caps to be used....
Hi people, I'm trying to design a 1 Watt push pull amplifier using dual NPN RF mosfet at 40MHz and a 24 Volt single supply. I'm not using any inductors or transformers. I'm not sure how to bias the mosfet correctly. What type of biasing circuit should I be using ? Since I'm using dual NPN, does this mean I need a phase (...)
Hi any one help me irfp250 push pull configuration what is maximum dc volt use how to calculate?(Vdss-200V - Rds_on 0.085- Id 33A) Regards kicha in a push-pull configuration the voltage across the mosfet in off state is double the power supply. Moreover there are spikes due to the leakage inductance of (...)
first circuit is you give supply voltage to the output or pull the output to gnd.. and second circuit open collector(if you use mosfet then open drain) you can just pull the output to gnd..
SELECT DEVICES. see the application notes. search google for "push pull amplifier" mosfet .pdf look for similar examples. start with
Hi, How can i design a simple push pull with mosfet (like the classical push pull with an NPN and PNP bipolar transistor) ??? At the input, i have a feedback current Amp Op and i want to use it to cancel the distorsion.. Regards