Questions tagged [mosfet]

A transconductance (using voltage to control current) electronic component used for switching and amplification. Acronym for Metal-Oxide-Semiconductor Field-Effect Transistor. (from http://en.wikipedia.org/wiki/Transistor)

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42 views

Laptop won't power up, no sign of life. I suspected X-ray

I know it's very unlikely that x-ray device harm electronics. But I have a laptop lenovo z5070 , 7 years old it's still nice to use some basic purposes, I upgraded it with a SSD drive one year ago. 4 ...
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33 views

Interpreting the value of transconductance shown in a MOSFET datasheet. Why was that particular value chosen to be shown?

Context: I'm a beginner in electronics, self studying MOSFETS. I'm trying to understand why the manufacturer of this MOSFET decided to provide a single particular transconductance value in the ...
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31 views

Trying to simulate channel length modulation effects to see practical considerations, finding negligible results

I'm a beginner, self-learning electronics, currently studying MOSFETS and I have been recently introduced to channel length modulation effects. I understand the theory behind it but after some ...
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N-Channel Mosfet LED Driver issue with PMV13XNEAR

I am testing the below which should be fairly simple unless I am missing out on something. Q1 is PMV13XNEAR. LED_CONTROL is being switched on/off by a PIC micro controller and I can confirm that it ...
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Why does my MOSFET fail? [duplicate]

The source, drain and gate are immediately shorted. There is an inductive load at the drain of the MOSFET and the source is connected to ground. The gate is powered by a voltage divider. However, my ...
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39 views

State space model of a PWM driven circuit

I am trying to write down the state space model of the circuit given below: As it can be seen above, a P channel mosfet transistor is driven by a PWM signal. I am trying to model the circuit ...
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282 views

Should an N channel MOSFET turn on when I apply the rated "gate threshold voltage"?

I purchased an N-channel MOFSET: FQP6N40C I'm trying to use a 3.3V microcontroller output to activate this MOSFET to control a 12V power source. However, when applying the 3.3V signal, the MOSFET ...
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121 views

Why does my MOSFET keep failing?

I am using the IRFZ44N MOSFET for my slayer exciter Tesla coil. The primary has 3 turns and the secondary about 1000 turns. The high voltage output has no load connected, it's just dangling mid-air. ...
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57 views

How to determine the current direction in KCL equation

I always having a hard time in finding the current direction in KCL equation. I ran across this circuit (small signal model for two MOSFETs) and want to find all of the current direct in s1 node. ...
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69 views

Voltage drop on resistor with MOSFET configuration circuit

I have big misunderstanding in calculating voltage and current across resistor in next circuit. I think picture well represent my question
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42 views

MOSFET N-Channel - RCD051N20

I have designed this circuit that outputs 7 or 28 mA depending is the MOSFET is closed or open. The gate of the MOSFET is controlled with an Analog Output from a DAQ that jumps between 0 and 10V. ...
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need help to make a speed controller circuit for 775 dc motor

i made this circuit with 555 timer to generate pwm, the mosfet i am using is irf540. But it is not working for me properly, i am getting maximum 4000 rpm without load but my requirement is to control ...
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Is there a risk of TO-247 Packages conducting current through the internal heat spreader?

It is common to mount a 2N3055 to the chassis. I want to know if it is safe electrically to do so with an IRFP260N and other TO-247 packages?
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Why does the below SPICE simulation show an initial current even before the voltage source is applied?

LT-spice simulation is showing a sudden jump in MOSFET current from 0 to 5mA at t=0. What would be the explanation for this? Is it a tool issue? All the capacitor initial voltages (C2, C1 and C4) are ...
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MOSFET PWM issue

I want to dim an LED and have connected a P-channel MOSFET to switch the high side. I added a N-channel MOSFET as a driver. The schematic is attached below. I'm applying a PWM sine signal from an ...
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60 views

Solid state relay versus n-MOSFET for controlling large loads with a microcontroller?

Let's say I'm trying to control a relay using a microcontroller. This relay requires a 500mA input current which is too large for a microcontroller to drive. It seems like I could use either a n-...
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68 views

Can I bias a depletion mode FET with a diode?

I'm trying to work out how to bias a dual gate MOSFET that I'm working with. Its behavior is halfway between depletion and enhancement modes. That is, its ideal VG range is about -1.5V up to about 0....
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56 views

Currentless voltage difference in MOSFET? [closed]

How does a MOSFET have a voltage difference on the gate without current running through?
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Using a power MOSFET for reverse current/battery protection

In the setup below, I am using an FQP47P06 power MOSFET for reverse current/battery protection. The picture doesn't show it, but the battery voltage is 36 V and the current passes through a 12 V ...
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96 views

Self resetting crowbar circuit for over voltage protection

I'm trying to design an over voltage protection circuit that doesn't rely on custom chips (the chip shortage has shown the danger of relying on this,) so I put together a crowbar circuit like this: I ...
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2answers
65 views

What does this mean about MOSFET load capacitance?

I was reading a paper regarding fault detection in combinational logic circuits and read something that I do not understand. It is about the downsizing of transistors making them more prone to hard ...
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What is the best way to find an RF FET device for a design?

I'm searching for a jfet or mosfet for a receiver front end, but there doesn't seem to be many options. Everything I find seems to be obsolete. The closest thing I've found to a component that matches ...
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63 views

How to separately charge two LiPo batteries wired in serial?

I would like a circuit where 1) two protected LiPo batteries are wired in serial to power the load; and 2) when external power is plugged in the load is disconnected and the batteries are charged ...
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138 views

PWM control of a water pump with a MOSFET - can't find the errror

I have a 5 V water pump and a 5 V/2.4 A power source. These work together. Now I want to control it with a PWM signal from an STM32 board using a FQP30N06L N-Channel MOSFET and that doesn't work - ...
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Is the VDsat the same for these transistors?

Here is the circuit : Can i say that the VDsat of transistors M1 and M1a is the same? And what about M3 and M3a? Also can i say that the VDsat of M6 is equal to : VdsatM6 = VdsatM1a + VdsatM3a ?
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Simulation of MOSFETs as high-speed switches

I’m trying to simulate high-speed switches (2xSPDT) made of MOSFETs. The MOSFETs should switch so that while “I2” flows into output, “I1” flows into “U_1” (or vice versa). I couldn’t interpret the ...
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86 views

MOSFET power on delay

I have a circuit where when first plugged in I need to delay a few hundred milliseconds to avoid trying to draw power during contact bounce/not all pins connected. I havent done much with designing ...
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122 views

Why does the MOSFET turn on?

I have this circuit for load sharing: VS1 symbolizes a 12 V power supply and V1 is a three-cell battery. When VS1=0, Vgs is negative and the MOSFET turns on, the load draws current from the battery....
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54 views

Need help understanding current source loading common source amplifier

For the circuit in the diagram, I observe that Vgs is around 3V and so is Vds on the breadboard. I do not understand if it is necessary to keep the drain at 1/2 of V1 as it is done when using a drain ...
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65 views

Driving high side MOSFETs

I am designing a BMS using BQ76940 IC. I will be implementing high side MOSFETs for charging and discharging. I read in a theory document that in order to switch ON the MOSFETs in high side, the gate ...
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85 views

Which has lower power consumption? BJT or MOSFET?

I on a project which is making a device with Arduino with low power consumption. There are multiple sensors and my plan is to power on and off the sensors when it necessary. So, use BJT/MOSFET as a ...
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Load sharing MOSFET selection

I have 3S series Li-Ion batteries and load sharing circuit. Like this link Sorry one-cell is shown in the figure but I have three-cell battery instead of one. How can I specify suitable P-channel ...
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Will a MOSFET operated above SOA, max. IDM (package limited), survive having the current pulse way narrower than SOA limit?

I am planning to use a protection with a PNP like this (approx.), for a PMOS device (schematic is just for illustration purposes, please ignore it). My transistor is FDMS86163P. In my simulations, ...
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What MOSFET is needed?

I'm working with a motor at 350 W, 36 V DC, and 13 A current. On the MOSFET info sheet, it says it should be able to handle all of this. I just want to confirm before losing buying as to not break the ...
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What is the "current - output high, low" referring to on these dual gate drivers?

(Not asking for component suggestions, please don't yank my question) I am looking at two components, (SI8230BD-D-IS and SI82391AD-IS) and think that they both could be used almost interchangeably. ...
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MOSFET Switch in 120 Vac application with Arduino Uno

I am working on a project that requires an Arduino Uno to activate a safety mechanism using 120 Vac from a power supply. I have little experience in electronics and EE. I want to ask if the following ...
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104 views

Is this a reasonable way to drive an H-bridge?

I currently need to drive a 400W (12-48V) DC motor via an H bridge. Therefore, I set out to think of a way to drive the motor itself and came up with something like this: I use drivers to drive the ...
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Connecting an Arduino to both panel and load side of charge controller, can this work?

I just joined this site because my searches haven't turned up an answer to this question, so apologies in advance if I missed something. I have an Arduino powered by the load side of a 12V solar ...
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101 views

When should you use a gate driver, and how do you choose one?

I'm building an amp using the NXP MRF300AN 300W LDMOS RF power amplifier device and was originally planning to use a DAC to drive the gate bias until @Hearth mentioned that I should use a gate driver. ...
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103 views

ESP (ESP8266/ESP32) Mosfet switch problem

My aim is to automatically power off the ESP by turning off the pinout. When I test the circuit I get the out voltage 1.6 V when I assume to get 3.3 V. What I'm doing wrong?
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How do LDMOS datasheets label current draw through the gate?

I'm trying to figure out how much current is required to bias a FET's Vgs so I can choose a DAC to set the gain. If I understand correctly, very little is required, but I couldn't find something ...
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21 views

MOSFET on-time calculation vs. measured

I'm trying to compare the measured on-time of a fet compared to the theoretical on-time of the fet. My calcs are not aligning with the measured result. Here is my approach: The fet is a NIKO-SEM ...
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On-state resistance limit in the MOSFET safe operating area figure

I'm trying to understand the upper-left corner of a typical MOSFET safe operating area (SOA) figure. Specifically why the region marked in red on the figure below, above the "Limit Rds(on)" ...
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How can I measure switching power losses in a MOSFET accurately?

I am going to measure under scope the switching power losses in the MOSFETs of my micro power inverter. In any case, the handling load current doesn't exceed 1 A at 24/48 Vrms. Firstly, I've thought ...
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60 views

What component should I use to regulate power during runtime? [closed]

I have been thinking about a way to reduce heat produced by my resistive wire based on some user input. My circuit is basically a simple resistive wire and arduino, both powerd by Li-Ion battery pack ...
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MOSFET current bidirectivity [duplicate]

Can this MOSFET pass current in 2 directions? I want to use it as switch but VCC and GND may be changed by the user. I'm worried about the diode inside.
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85 views

Invented logic switch to supply power to DC/DC

I have a controller where by the GPIO's pins when ACTIVATED is pulled low. simulate this circuit – Schematic created using CircuitLab I want to use transistors and FETs in such a way that when ...
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Why is my MOSFET ON when there is no gate voltage and OFF when there is a gate voltage? [closed]

I have been working on a coil gun but am having trouble with the firing mechanism. My coil gun capacitor bank supplies 400v and instantaneous current of 666 amps based on the resistance of the coil. ...
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64 views

Odd step preceding square wave in simple brushed motor driver

I am attempting to build a simple controller for a cordless angle grinder motor. I have constructed a very simple motor controller, but when running it under load the MOSFET keeps dying. The schematic ...

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