Questions tagged [mosfet]

An 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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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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Reverse polarity protection for battery powered application

Im designing battery powered application and need reverse polarity protection. My system specs: 4.5v(3x AA batteries) in and system running on 3.3v. Im using MCP1711T-33I/OT LDO to convert 4.5v to 3....
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81 views

Freewheeling diode position [duplicate]

I have a pneumatic solenoid valve switching from IRF830 MOSFET. Solenoid valve connected to MOSFET by 2-3 feet long wire. It's necessary to use a freewheeling diode for this? What is the most ...
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115 views

MAX809 driving a mosfet

I am building a circuit that stops giving power to the load when the voltage drops below 3.08V. I am using MAX809T (3.08V version) and a SI2302 mosfet (\$R_{ds}\$ on 0.056Ω@2.5V) When there is no ...
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Should I use a resistor between the gate driver and MOSFET (gate pin)?

I'm making a PWM driver for a DC motor. After some questions were answered in this post, I ended up with this schematic: And I have some new questions: Do I need a resistor between the gate and the ...
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50 views

In a thin-film transistor (on insulating substrate) what is the difference between putting a load on the source or drain side of the transistor?

My question was incorrectly posed, because I didn't include the capacitor connecting the gate to one of the terminal. So in fact this question is regarding common source vs common drain comparison...
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107 views

Using transistors to switch 12v from a 3.3v signal

I'm a pretty accomplished programmer, but working directly with electricity is giving me the fits. I'm trying to replicate a design that switches a 12v/300ma solenoid based on a GPIO signal from a ...
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38 views

How to drive +-10V Gate-Source N-MOSFET from 30 V

I have N-MOSFET with maximum +-10V Gate-Source voltage and I need to drive it with 30V signal. Is voltage divider way to go?
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211 views

15kV High voltage pulse generator circuit how to have digital control?

first of all I'm fairly new to making a more complicated circuit. I'm trying to make a PCB with an ATmega328PB chip on it. And with that chip I want to control a High voltage pulse generator (Arc ...
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606 views

P-MOSFET failing

I am using this solution to drive a large (huge) relay on a boat. The system works well for months on end, but eventually the MOSFET (T2) dies suddenly. I have modified the schematic to include the ...
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90 views

NE555 power controller not working with big motors

simulate this circuit – Schematic created using CircuitLab Backstory: Ok, so I thought that a making a PWM controller would be a fun weekend project, it's been a week now and I still can't ...
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51 views

Inverted high impedance / pull down circuit

I'm devising a circuit to control the shutdown input on an integrated circuit. The IC accepts a high impedance input (can't be pulled to any voltage) to enable operation, or it can be pulled down to ...
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63 views

How to detect MOSFET's open or not

In case Vgs is supplied and equal or above of its threshold level so that I expect it's open, but how about a fault occured which I don't know, how can I understand it's open or not by looking on its ...
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153 views

Maximizing efficiency in synchronous boost converter

simulate this circuit – Schematic created using CircuitLab The aim is to design a synchronous boost converter using a microcontroller ATMega 2560 switching at 31.25 kHz. 5V PWM signal is fed ...
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37 views

Values of components in ACPL 337J

I was going through datasheet of mosfet gate driver. I wonder why is the value of component the specified one only. On page no. 13 fig 23, why the value of resistor between pin 3 and pin 6 is 10k ohm ...
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Questions regarding Gallium Nitride semiconductor devices in Switched Mode Power Supplies

I have a couple of questions regarding the use of Gallium Nitride MOSFET devices in a DC/DC converter design of mine. My topology is an LCC full bridge converter. My knowledge is not at expert level ...
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148 views

Problems with dc motor driver design: Mosfet fail

I made a brushed dc motor driver. The motor speed is controlled with PWM (from an Arduino). The motor that I'm using draws 3 amps without load. This is the schematic: As you can see there are two N ...
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Electronic load, Problem turning MOSFET on

I am trying to make an adjustable dummy load to test a 12V supply, I’m having trouble with the op-amp feedback circuit. Attached is a simplified schematic. I have tried lots of things and stripped it ...
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43 views

What is the benefit of a mosfet gate drive which is constantly biased instead of driving to ground?

I recently came across a circuit with a drive signal which never went to ground, and instead always kept the MOSFET biased. What it the reason/benefit of doing this? I've drawn an example like the ...
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39 views

negative Vds in SMPS!

Hi, I am designed a full bridge SMPS, like the above schematic. But when I measure the switch node voltage (I put voltage probe across Q2), I see when the mosfet is on, the voltage across it is -1 ...
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75 views

Switching speed of MOSFET and BJT

I've read on the internet that MOSFET is faster switching device than bipolar transistor, however, i don't understand why. Considering the fact that transconductance of bjt is grater than ...
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54 views

Half Bridge Low Side Mosfet vs. Flyback Diode

I intend to use this high side switch in a PWM application with a brushed 12V motor drawing 8A steady state max: https://www.nxp.com/docs/en/data-sheet/MC33981.pdf The switch allows for a half bridge ...
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107 views

DC boost converter output voltage problem when load is connected

I have successfully finished one part of the DC converter. Now I came across a certain problem which I can't solve myself. When I didn't connect a load to the output of the dc converter, there was ...
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140 views

LED to switch ON when an analog signal is outside the range of -10V to +10V

I would like to make a simple circuit to detect when an analog signal goes either above +10V or below -10V, and switch on a single LED if either of these cases occur. I have available only +12V and -...
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48 views

How to find Gate charge

I want to drive a 650V 21A SiC mosfet at 100kHZ. Would this mosfet driver be able to drive the mosfet? How can I find Gate charge of the mentioned mosfet gate driver? The mosfet I am planning to ...
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Test circuits for testing input and output capacitance of an NMOS spice model?

As the title states, I'm having trouble finding resources online for confirming the capacitances of an N-MOS spice model. If there are any resources someone could point me to to learn more or test ...
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31 views

MOSFET channel length

Good day, If you look on google for ARF446/447 in the datasheet you won't find the channel length (in micrometers). I need it to calculate the unity gain cutoff frequency. Also in the case of IRFP360 ...
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Question about a mosfet driver gate resistor

I'm considering the ZXGD3003E6 for driving an N-channel MOSFET - PSMN4R5-40PS,127. There is a typical application schematic in the MOSFET driver datasheet (as shown below). My question is how do I ...
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37 views

Gain of a Dual Gate MOSFET

simulate this circuit – Schematic created using CircuitLab This is the schematic of the circuit but tried to find the gain of this circuit, assuming 50 % of the Duty Cycle for the LO, and M2 ...
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144 views

Complementary transistor pair with a bipolar transistor and a MOSFET

I own a set of Soviet IN-14 Nixie tubes and I would like to use them to make a vintage clock. I found this example schematic of a "Nixie clock": I don't understand what is the purpose of using a ...
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89 views

Difference between cutoff and subthreshold region of nmosfet?

I understand that some current does flow from drain to source when Vgs is below vth and Vds is greater than zero. But why this has a different name?(and a different region in Cadence virtuoso tool) ...
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Where do the electrons come from in nmos channel formation? [duplicate]

For a NMOS, when gate potential is increased from 0 to say 0.1V, the holes in substrate feel repulsion and moves away leaving negative ions behind. But what exactly happens when the gate potential ...
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189 views

High Side Switching Inductive Load with MOSFET

I am attempting to make a PCB that high-side switches an inductive load (water pump) that draws 4.6A peak. The switching scheme will not include any PWM, just basic on/off functionality. My concern ...
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57 views

Can MIC4102 be used to drive Boost Converter

I'm trying to design a high-power Buck-Boost converter, which is meant to convert a 45-63V input voltage into a "constant" 48V. The application requires quite high currents (up to 20A continuous). The ...
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95 views

Switching between battery and external power sources with reverse polarity protection

In my design, I will use AA batteries to power the electronics board. As a requirement, also it should accept the power from external power supply (12V) - The board should automatically switch from ...
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1answer
61 views

Razer Laptop Power MOSFET replacement

I have a failed power mosfet on my board which is PSMN3R0-30 https://assets.nexperia.com/documents/data-sheet/PSMN3R0-30YL.pdf It has low Rds (on) = 3 mΩ It is common for these to fail in these ...
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65 views

Mosfet Gate Resistor

I am building a high power ZVS induction heater. I originally used this famous design. It worked like a charm when I used a 48v 31A power supply. But I want an upgrade. I recently got a few of these ...
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AND gate circuit using mosfet

I'm trying to design an AND gate using mosfet. But it failed at one state. I did the same design with BJT and it works correctly. You see when it's one end is high and the other is low, it gives a 3....
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102 views

Normally closed mosfet circuit

I'm designing a battery charging circuit for a portable device. Conceptually it looks lik so: simulate this circuit – Schematic created using CircuitLab As a safety function, the circuit can ...
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65 views

Current monitor circuit not working

For part of a project, I am needing to monitor the current draw of 4 low power loads simultaneously. I like experimenting with circuits and I found one online in a TI application note (AN-31 page 35) ...
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141 views

Multi channel Mosfet driver ghosting between channels (with suggested fix)

I´m pretty new to the forum (as you will see by my limited electronics knowledge) and I have a wierd problem when trying to control some automotive fans at variable speed. The fans each have an ...
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Driver circuit calculations

I am attempting to built this circuit here: It is used by an LED manufacturer to provide pulses to a high-power LED. In my case, I'm using an ARDUINO to provide the TTL signal. I haven't sourced the ...
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Obtaining D flip-flop mosfet-level schematics from CMOS layout

Could anyone help to derive D flip-flop mosfet-level schematics from the following CMOS layout described in this conference document : Open Cell Library in 15nm FreePDK Technology ?
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Simulation mismatch when shifting a +5v pulse to -12v

I am attempting to switch a N-channel mosfet (IRF740) running on a -12v rail using an arduino which outputs a 0v/+5v pulse. The end goal is to supply a -12v/-7v pulse to the MOSFET gate. After four ...
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MOSFET Capacitance clarification

2 part question here. Are there ways to directly test the input and output capacitance of a MOSFET, Ciss and Coss? On that note, due to internal inductance and capacitance, is it possible for a ...
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149 views

Why does this Mosfet get Hot?

I have an IRF740 mosfet that doesn't get hot in one circuit but then gets completely hot in another identical circuit and for the life of me can not figure out why. Well the circuits aren't exactly ...
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299 views

Problem driving IPB065N15N3G MOSFET with HCPL-316J driver

I want to drive an IPB065N15N3G MOSFET. I am making a boost converter. The driver I am using is the HCPL-316J (a combined optocoupler and driver). Below is a picture of my schematic. Please tell me ...
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How to import MbreakN model from Orcad PSPICE into Tanner T-Spice?

I worked in orcad PSPICE with MbreakN and MbreakP transistor. Could any one help me out to import it to tanner T spice. I have tanner Version 13 and working with 250 nm.
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41 views

High amp multiphase buck

I am looking at designing a multiphase buck that needs to operate from a truck battery (24V) and has a constant output of upto 100amps at 24volts. We need to be able to set the exact amp draw with in ...
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50 views

Effective resistance of a NMOS

How do we calculate effective resistance of a NMOS, operating in linear region across drain and source?