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871 Threads found on edaboard.com: Mosfet Problem
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??
Hello to all. I am trying to design a VCO in 90nm TSMC. The problem is that the current mirror i am designing has large mismatch between the Iref and the Iout. I am using rf nmos transistors to design it. The model i have available has maximum length in nmos 240nm. Can i use a dc mosfet to design the curent mirror? Thnx
i use this mosfet the schematic is the gate of the PMOS is connected to Vcc and the gate of the NMOS is connected to GND, the problem that i found there is a current that pass th
Hi I have been researching and reading everything i can about mosfets and H-Bridges and have come up with the attached schematic. can someone please tell me where i have gone wrong and why i keep destroying my mosfets. I am wanting to run a single small motor in both directions with variable speed. I have a switch mode 9v power source com
A. Situation -------------------------------------------------------------------------- 1. I wanna a pulsed current(1mA, 0mA) to a load resistor(R0). 2. M1, M3 are current mirror pairs. 3. M1 is generating a Vgs1(for 1mA) and M3 is copying a Vgs1 so that M3 can flow current of 1mA. 4. M2 is a switch for shorting and opening between Vg1
there a way to protect the mosfets from saturating using resistors or capacitors? Due you are under development stage, I suppose you are using a DC regulated power supply, with limit current protection, wright ? That´s the standard procedure, and if the case, there is no need to do that you are asking.
Hi! I am trying to build a high power speed controller for a DC motor. I want to control the motor only to one direction. I decide to use a single mosfet with a mosfet driver as the following schematic
Dear friend, Each mosfet model has its merits and drawbaks, like accuracy or simulation time, thus converting them maybe loss the accuracy. some programs like @dv@nced D esign Sys. can open all spice format like HSpice or PSpice without any problem like mosfet modeling incompatibility,also this new softs. have a large number of known and (...)
in fact,you problem is not so easy.but if you want low power dispension,maybe mosfet is the only way.you can use four 20V 0.005 oum mosfet parallel,get a very low instance, only about 1W dispension,and four SO8 chip mosfet can work well with about 30 degree temprature warry about others,if you find a error in one power (...)
hi,can anyone can tell me about how to reduce the rf noise of SMPS? and a strange problem,a build a smps of about 50w ,24v2a.when it works,sometimes is good,but sometimes it will sent out 100Hz sound noise,i find when this hanpens,the voltage of mosfet drain is not the same as it works well.but sometimes it will be ok after a few seconds,and maybe
Consider the DC operating point of both circuits. The second-stage's gate voltage is VDD-|VDS(MP4)|, and approx. equals to VDD-|VGS(MP3)|. This voltage is what the left-hand figure needed. In the right-hand figure, however, the Vgs of the second stage's mosfet will be much greater than Vthn, and changes with power supply -- VDD. This is not desirab
sorry .. how large leakage current about your powerMos ?? as I know power mosfet Ids =6A Cgs=1000p leakage = 0.1ua (Vds=0 Vgs =20v) or SI2031 have large leakage current ..
I have a mosfet that controls a dc motor. Without snubber, mosfet gets hotter and hotter. With a diode snubber, this time diode gets hot. I used a slow diode. I'll also try a fast diode but i wonder that does snubber helps to reduce the dissipated power or does it take it from mosfet onto itself? I mean, must i use a huge diode or can i (...)
I have a 24V dc motor. I'm driving it using a mosfet by using pwm method which is at 20KHz. I remember that i was able to apply max voltage(I mean i suddenly apply any duty cycle e.g. %50) and the motor was responding it before. I don't know what happened but know the motor doesn't start normally. It starts if i connnect a diode across the motor t
It looks like you are making a constant current source or current limiter. You will need to use a P type mosfet for the series pass transistor and put the source to the input and the drain to the output. This is a good situation where SPICE type simulators are very good because you can examine the simulated currents. PSpice has a free studen
If you use normal enhancement nmos (nmos outside nwell) as cap, the S, D and B terminals should be tied to VSS. Only the G terminal can be connected to other node. If you want a mos cap not connected to VSS, please use mosfet in nwell -- either nmos in nwell or pmos in nwell. On the latter case, the mosfet should be properly biased.
I assume the 'high power' of the DC motor is 'DC power supply'. If it's DC power supply, probably you could use mosfet or IGBT to replace the Triac. Can you have that option?
i have problem? i can not design circuit. i want circuit? Plese help me thank.
Speaking for BSS89 small signal nmos, If I do not use gate resistor then the transistor is more likely to be damaged. I throw away tens of these mosfets to find if the problem realy comes from unused gate resistors...and now I am sure....
The mosfet gate drivers are used to ensure a complete on/off state for mosfets . Also, if the mosfet is a high side switch the source will be considered as a floating point while it is not tied to the ground , so it is important to ensure that the voltage Between the gate and the source is more than 12 v to avoid the negative temperature (...)
Hi,sandusty I think the difficulty is the SDF is used for STA and other post simulation,it is from the netlist and library. Unlike analog RC extraction (they can get RC parasitic form mosfet level netlist and layout),it need the timing information in your library,unfortunately,that is what you haven't. So if you want to go on,maybe you can do
I'm trying to drive a mosfet using ir2110. I tried a lot of thing but still couldn't get an output from the 2110. Both high output and low output doesn't give a voltage output. They ara always at zero. What may be the problem? Please help because i'm stuck badly.
hi i'm newly joined member in this forum... doi ng my project in m.tech.. well i'm building a hardware circuit for 60 watts AC-DC 1-φ buck converter... the problem is with the mosfet gate driver. i'm making use of ir2110 driver... as i want to isolate the pulse given to the mosfet so i'm giving pulse only to the high side drievr... (...)
i am design a LNA with ADS recently, now i need to analyze the Fast, Slow, and Typical case of the mosfet in order to find out impact of these three case on the total LNA circuit. I am using TSMC0.18 process. But I do not know the details of Mento Carlo analysis setup in ADS. i wonder who will tell me or give me a document about Mento Carlo analy
Hi all there is a nearly 4Vdc offset in the signal that drives the high side in my H-bridge and i don't know how to remove it . i didn't have this problem when i was driving the motor with a high side switch only i added a RC snubber circuit across the drain and source and every thing was working well i.e no offset ,sharp on/off , n
Hai I want to know which are the capacitances that wll be effected by scaling of a transister.What are the new capacitances that will come into picture.
Your gate must be positive against the source. Thinking upper sides, source side of the mosfet is at bus voltage when it is open. So if your bus voltage is say 48V then your gate must be 60V or so according to the ground and 12V (If your gate needs 12V to be driven) according to the source. To accomplish this, you need a bootstrap circuit or an iso
The problem is of course that you cannot drive the mosfet into saturation. The eaiest thing to do is use a P-ch device and reverse the signal of the PWM. Else, use a charge pump to generate a voltage about 8-10V higher than the input voltage and power your controller from that voltage. That way you will be able to always drive the (...)
Anybody can tell me the meaning of voltage headroom, is there any relationship with voltage swing, thank you very much!
hi, i want to design a h-bridge to control a dc motor. (24V ~15A). i chose mosfet as power switching element. do i need to use mosfet driver component or not?. if i need why? isn't it enough to drive a mosfet drectly using dc voltage.
you can drive step motor with mosfet as like as bjt ,when a signal like as signal come from pc or micro the mosfet must be on and the signal can travell throw this part like switch or relay it is very nice !! isn't it? you must bais mosfet for larg signal.. it is very easy easy than bjt.
I have an IRFP350 commuting 340V to a 71Ohms load. The mosfet need dissipate 28W. If I fix the transistor to the case, this quantity of power can be dissipated, but the problem is that this case is accessible by the operator (the case is electrically connected to the earth terminal). Any body can tell me what kind of insulator can I use in order t
Hi, In Razavi, problem 2.13 (page 40): " The transit frequency of a mosfet is defined as the frequency at which the small-signal current gain of the device drops to unity while the source and drain terminals are held at ground". How can there be current in the transistor when Vsource=Vdrain=0V? As far as I know, this is defined as trio
Hi, i am simulating this circuit using M*I*C*R*O*C*A*P VII and i am not getting any results. In my opinion it seems to work, but that's not what i am getting. I have to build a simple power amplifier to output AC current to a capacitive load, so i decided to use mosfet as output amplifiers (operating in class B). I believe that the OPAM
Hi all i am designing a driver using cascade of inverters to drive a large capcitance (20pf)! But the delay is too large beyond our requirements. The delay should be less than 4.5ns. the power is 1.5v and i use the p35(n35) mosfet. So any other method to do the same thing? i use the UMC0.25u. i want to know if the p25(n
Anyone can helping me to solve my problem? I needed someone to show me how to find the compatible part for Power mosfet STP60NF06. Cause currently in my country- Malaysia can't find this Power mosfet. For your information, this Power mosfet is used in Uninterruptible Power Suppl
I got a problem in a LDO design with standard cmos. I use pmosfet as the pass transistor but the ron is too large even I apply a huge w/l ratio. The dropout voltage increase significantly with load current. Is there any way to impliment a low ron PMOS as pass transistor?
Normal IR remote controls pulse the LED at 1~2A. That is right, amperes. Thus, for a 5V supply you need about a 3 ohm resistor in series with the LED. Use a transistor that can give you that peak current, either mosfet or bipolar. If that still does not solve the problem, use two or more LED's, each with its own series resistor and drive them
Dear I build a simple avr circuit that on/off a small dc motor.The power supply of circuit is a simple linear regulator(7805).for driving the motor a power mosfet(irf9540) was used.But when motor is on the avr did not work correctly and reset and lock. I used an filtering of power supply by inductor and tantalium capacitor but this problom oc
When i was simulating the boost converter,i found the power dissipation on the switch mosfet sometimes was bigger than the power source,and sometimes approximated to the power of power source,then the total power dissipation in the converter components was bigger than the power supply ,so where does this power come from? Is my simulation method wro
For two series connected Nmos, i have apply a Vdd at M2. Please refer to attachment(voltage.jpg). I am intrested to know the current flow. How to make such calculation? Other know value is gate voltage of M2 and gate voltage of M3. Since the Vds2 is Vd2-Vs2 and Vds3=Vd3-vs3, now i dont know what is Vd3 and Vs2, how to calculat this ? cause
Hi I'm working with MultiSIM 8 to design an Amplifier, but I need 2SJ162 and 2SK1058 mosfet's, I found this link but when I created these components and simulated the circuit I had an error. I thought that these models are wrong. I hope you can help me. Thx. PD. Sorry but
The circuit as shown has no switching driving ciruit to drive the mosfet gate, , as u connect the gate to the 12 v positive of the battery , means that the motor operates continously, i.e. no inductive overvoltage will happen,. This makes the o.v. cause out of occurance, i think the mosfet explodes due to insufficient gate voltage to achieve li
Hello, Does anyone have a good way to protect a mosfet that is driven by a PIC from a short???
i mean how to calculate mosfet circuit (h-bridge) i want to control motor. i want to equation concerned with mosfet. Pleace advice me. thank u
I have a problem with this circuit (see the atached file please). When J3 is closed and J4 is open the led is on because the mosfet is conducting. How could avoid this problem. This circuit represent a backplane with two cards. And what I want is: - J4 closed and J3 open or closed (doesn't matter) then LED2 is on. - J4 open and J3 open (...)
i like the idea of going to 100V. your motor's winding inductance is large, so there is probably some killer voltage spikes that need to be properly addressed. mosfets come with their own body diode (well, 99% of them do) and so you should not need to put external another diode! check the datasheet for the diode conduction ratings, you wan
THANKS A LOT FRIEND. I FIXED THE TV BY REPLACING THE mosfet AT THE POWER SUPPLY AND IT WAS OK. APPARENTLY A COCHROACH SHORTED BETWEEN THE GATE AND THE DRAIN, DAMAGING THE 'FET.
Hi, I'd like to run basic gm/id methodology on nmos device to extract the plot of ft versus gm/Id, Id/W versus gm/Id, and Id/W versus vgs-vt, etc. But when I plot those relationship in calculator with "OP" operation, it does not show me the right figure (The curse is straight, it seems that cadence only give me one operating point when I sweep t
hi when i do swept PSS only run on Variable say Resistance value How to see Current in certain component i try in direct plot window choose current but what terminal shoud i select it give error invalid selection is there another way to view current variation in mosfet transistor by the variabl