Questions tagged [mosfet]
Metal-Oxide-Semiconductor Field-Effect Transistor, a type of field-effect transistor (FET). MOSFETs have an insulated gate, the voltage of which determines the conductivity of the device. This can be used for amplifying or switching electronic signals. (From: Wikipedia)
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Cannot find what causes faults on DRV8353RH
I keep getting faults on a a new batch of ESC boards based on the TI DRV8353RH & Infineon IPT020N10N3ATMA1. Please consider:
When starting a motor at 48V - 56V the DRV asserts a fault after ...
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Parasitic capacitor current of an inductor
I am doing a double pulse test on SiC MOSFETs from 100-800 V and current from 20-80 A. The schematic is shown below (the values are not correct though):
In my first round of tests, I was getting a ...
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High Frequency Oscillations on Mosfet Gate
I am working on a circuit that drives an inductor at its resonant frequency. However certain models of MOSFET I simulate the circuit with experience oscillations at the MOSFET gates as pictured below. ...
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How to mitigate excessive ringing in VDS and VGS
I have a few questions regarding my measurement results in the lab for a double pulse test setup. There are three issues which I want to mitigate
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At turn-on interval, there is excessive ringing in ...
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FET between two grounds, could my circuit idea work?
I have a circuit that does not work as I intended/expected. It's been over a year since I worked on it, but recently Farnell send me the FET I originally intended to use but became "out of stock&...
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Snubbing an H-bridged motor
Mostly a follow up to https://electronics.stackexchange.com/questions/175778/rc-snubber-across-switch-or-inductor…
I've seen RC or RCD snubbers across the switching MOSFETs (and these damp the dV/dt ...
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Sinking an input when pulses are above a certain frequency
I'd like to use a liquid flow meter of type YF-S401 at 12VDC. It produces 1.7-35k pulses per minute (rise time: 0.04us, fall time: 0.18us).
I want to trigger a sinking input of a controller board if ...
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Review of electric circuit with Arduino
I am currently working on a project for which I am in charge of the electronic circuit. Since I have never worked with electronics before, I am really desperate and unsure whether what I am doing is ...
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Fixing overshoot in current regulation of AC electronic load
My AC electronic load (previous question here) shall have a constant-current mode. It is being simulated in LTspice.
@devnull helped design the circuit for AC loads, but for simplicity's sake in the ...
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How to determine Vds(on) and Vds(off) for switching loss calculation?
In the Infineon Application Note, two of the parameters they've used to calculate the switching loss of the MOSFET are Vds(on) and Vds(off).
Is the Vds(off) the blocking voltage?
Where do they obtain ...
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MOSFET Without Gate Resistor is Failing
I have two MOSFET circuits; one is working and the other fails and I'm not sure why. I just want to turn on/off the LED, nothing special, no fast switching.
Below is the working circuit (series gate ...
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How to use MOSFET in avalanche mode?
I'm thinking of a very simple circuit to generate high voltage pulses, like this:
simulate this circuit – Schematic created using CircuitLab
The MOSFET in this case will turn on until the ...
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Controlling 5 V / 2 A power with a photodiode (sensing red/green LED)
I am trying to design a circuit that will switch a 5 V / 2 A power on or off depending on voltage on a photodiode. If the voltage on the photodiode is below 40 mV, then it should be “ON”, otherwise “...
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Very High Spike and Unusual MOSFET Gate Switching Signal
My apology if I describe something wrong in this question, English is not my native language. I've been trying to work on a bidirectional converter simulation, but there are a few problem I met with ...
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Transient Negative voltage on NMOS causing channel to open?
This is my first post here. I am an electrical engineer looking to cure my madness because a 2N7002 NMOS is doing things I cannot explain. If you look into the attachments, you will see some screen ...
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Which parameters should be compared to to replace N-MOSFETS with different package but with same pin functionality?
Since NTZD3154N is used a lot in my design, and I have BSS138PS only for used for one circuit, I want to replace BSS138PS with NTZD3154N in the following DP++ Auxiliary Conversion Block:
Note: This ...
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Creating an LTspice model of a MOSFET not in the standard library
I want to model this power MOSFET in LTspice.
I went into the standard library and noticed that all the MOSFETs there are created by VDMOS(...). Reading up on this command in this resource, I noticed ...
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Stability simulation - breaking the loop for a MOSFET - op-amp current source
The task at hand is to create a voltage controlled current source of 60 mA driving a valve coil (64 mH, 139 Ω). I am aware the MOSFET used is insufficient powerwise; it was a quick attempt to have a ...
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Why do we use silicon in the crystal direction [1 0 0]?
In MOSFET, we use silicon in crystal direction [1 0 0] , while we use direction [1 1 1] in BJT. What is the reason? I expect the opposite, because we see more atoms on the surface in the direction [1 ...
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Connecting two identical mosfets in series
I'm required to prove the above claim. I've written a few equations in my attempt to prove that and some of them obviously might not make sense.Could you tell me please if I'm in the right direction ...
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MOSFET transistor with coupled drain and gate
The below circuit is part of a КР580ВM80A, a clone of an Intel 8080 by Vslav.
I'm trying to understand the purpose of coupled transistors T1 and T2. Vc is 12 V.
What will be "state" or ...
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High-side mosfet switch placement
this is a power circuit I'm trying to complete:
the button at top turns the curcuit on, supplying VCC to mcu, and the MCU will output a high signal to a pin (marked in pink) which turns the N-MOSFET ...
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Half-bridge circuit not working, high side running hot
As I'm a noob in this field I’m experimenting with a half bridge circuit to run a buck converter to learn about it. First I tested my circuit by putting everything together on a breadboard and it ...
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MCU, N-channel MOSFET, ~15m led strip, 24V power supply. Whats happening?
Disclaimer
Hi,
Firstly, I'd like to underline, that I do not have masters degree from electrical engineering and I didn't study electrical engineering on high school. I'm software engineer who likes ...
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Danfoss BD2.5 on 12V starting problem. Good signal on only one gate of both driving MOSFETs
The winding resistances are OK, not shorted to ground. One of 3 compressor coils is 3.6 ohms (should be 3.5). Driver coil resistances is 0.2 ohm instead of the normal 0.3. Compressor turns 1/2 turn or ...
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Eagle SPICE MOSFET Simulation Has the Wrong Operating Point
Having a lot of trouble getting an N-Channel MOSFET to work correctly in any spice program. Trying something really simple to get started and I can't seem to get the MOSFET to "turn-on". ...
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Using a single MOSFET as an RF switch
I'm assembling a receiver kit from QRP labs. It is an inexpensive kit designed to cover HF. This kit has a BS170 at the input which I assume is intended to disconnect the receiver when the transmitter ...
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How to suppress noise in my circuit
I illustrated what my circuit do as you see. Switching frequency is 800 Hz. When I increase the load, a noise is heard from my circuit.
Here is my drain oscillocope view in frequency domain. What can ...
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Pulse Transformer design problem: cant understand for sure whats the reason or irregular output waveform?
A ferrite core pulse transformer provided with 12V PWM signal (as primary winding input voltage) as shown in Fig-1, produces irregular output voltage across the secondary winding as shown in Fig-2. I ...
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Bootstrap capacitor calculation - Which formula should I pick?
In order to calculate capacitance of bootstrap capacitor, I searched around and found two different formula from Ti and Infineon. The Ti version states:
while Infineon version say:
I think the basic ...
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Calculate the junction temperature of a MOSFET during pulse
Hi all I have a question regarding using a MOSFET for a constant current source. I have found this question with some answers but it wasn't clear to me yet.
I want to create a constant current LED ...
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Large negative current spike in N-Channel MOSFET source when turn-off
I am working on repairing a power supply board of a LCD TV (200W power), more specifically, the PFC section (active power factor correction). See schematic (adapted from here):
I've replaced some ...
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Controlling IRL2703 with 3.3V (Reading MOSFET datasheets)
I have an application where I want to switch on/off a resistive load (24V/300mA) from a 3.3V MCU GPIO pin at a rate of 1 HZ or slower. I also have some IRL2703 MOSFETs, and I wonder if they would do ...
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Remote relay control application with a MOSFET
I need to control eight solenoid-valves for water drainage outdoors, remotely and simultaneously. The valves are normally closed (NC) type which I guess, in that context, means they open and let the ...
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Gate of a transistor and mosfet damaged
In my schematic, I found that the base of transistor Q7 (2n2222) was damaged. I tried to replace it with a BS170 MOSFET, and the same thing happened where the gate was damaged.
The microcontroller ...
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Load Sharing/Isolation Circuit with ADP5063
I'm designing the battery power/charging circuit for the Reform DIY laptop which uses a (big) LiFePo4 cell. For the charger IC I've now settled on ADP5063 as it seems simple and can charge with 1.5A ...
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Level shifting with BSS138 - weird values
I need to connect 5V and 3.3V devices via I2C as follows:
I've connected 3.3V and 5V pull-ups and tried to measure the voltage. There is 5V on HV and TX_HV but 4,7V on LV / TX_LV.
Putting TX to LOW ...
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Help identifying this MOSFET
Trying to figure out what this is, and suitable replacements. Markings are "1 Wt 77" Cannot seem to find anything.
Edit: I removed and sized it today, looks like 2.04 mm square package, ...
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Why does the signal MOSFET keep failing in this circuit?
The following is the power control part of the circuit I use in my car to control the wing mirror folding motors, the idea is that the whole circuit can power itself off after its done its job to ...
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Peak Current in Electrical Discharge Switch FET
I am in the process of a designing an Electrical Discharge Machine (EDM) pulsed power supply. Many designs use a power FET to switch the voltage from a supply cap to appear across the spark gap where ...
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PMDC motor stops spinning when speeding up with pedal
I am driving a PMDC motor with a half bridge circuit in which the low side MOSFET is a freewheel diode and it is always at "on" stage. I am only switching with the high side MOSFET via an ...
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DC-DC Converter MOSFET Failures
I've been seeing failures in a few of my circuits in which Q17 and sometimes also Q16 are failed closed in the DC-DC converter. MOSFETs used are Vishay SiHP12N50E.
Below is a schematic reference for ...
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Circuit that turns on an LED and turns it off after some time
I want to create a circuit that turns on an LED when a switch is flipped and automatically turns it off after some time. I use a capacitor for the timedelay.
Because I want it to be able to be reused ...
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ESP8266 + MOSFETs + LED strips
I'm trying to drive with PWM the usual 12V LED strip with a WeMos D1 Mini and a bunch of MOSFETs.
Here's the circuit:
What do you think of it regarding MOSFET choice and resistor placement?
Edit (...
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FET Drive for 200A Battery Charger Question
I have 12V, 650A-hr house batteries I want to charge from the alternator when traveling. The alternator has a continuous rating of 240A @ 14.6V. The alternator regulator drops the voltage some.
The ...
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High-side switch on N-MOSFET for 1-Wire
I have two devices that both control 1-Wire data line:
The system is designed in a way that only one of devices will be working and another will be in power-off state. When device is turned off it ...
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Relay/Mosfet circuit for outputting source of highest voltage?
Currently using ntc thermistors to measure temperatures, I’m then using a comparison circuit to filter through a set of 3 thermistor-passed voltages (outputting the highest voltage).For overall design,...
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MOSFET is messing up the voltage seen on the drain, when it should be either an open or closed circuit
I have this eFuse which uses voltage dividers to turn on an enable pin, and also set the proper voltage threshold for over-voltage protection. This circuit works just fine on its own, but I wanted to ...
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Design of heatsink - increase in ambient temperature during heat transfer
I have gone through few resources available online on how heat flow from die to ambient and how its is modelled as current source, thermal resistance and ambient temperature as voltage source.
I have ...
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MOSFET body diode current rating vs Schottky diode
How is it possible that a MOSFET's body diode in a TO-220 package, such as the N-channel IRL3803 or P-channel IRF4905, has a much higher average/continuous current rating than a high-current Schottky ...
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