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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Problem driving MOSFET with ACPL 337J optocoupler

I want to drive a mosfet. I am using an ACPL 337J optocoupler to drive it. Here is the schematic:- But I am facing problem while driving the mosfet. The signal at gate of mosfet should be a PWM but ...
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41 views

Switching 48V using irfz44n mosfet

I have a 48V source which i need to turn off and on using an irfz44n mosfet. I can give a gate voltage of 16V at maximum. What would be the circuit? The 16V gate voltage is being obtained from an op-...
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26 views

Nanopower Fiber Optics / MOSFET Switch

I'm a newbie at designing at the nanopower level, hence my question. In this circuit, I have plastic fiber optical inbound signal that drives D1 photodiode, whose dark current is extremely low (tens ...
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48 views

Replacing TO-220 MOSFET with SMD DPAK

This MOSFET IRFBG30 is being used in an old design. It even has a little heat sink attached. The FET is used as a current limiter. During normal operation, a current about 13 mA passes through it. ...
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91 views

Why this H-bridge with only N-channel FETs didn't work?

Based on this answer here in StackExchange and the Motorola article it cites, I've designed a dual h-bridge motor driver with push-pull transistors to switch the FETs faster, layed out a PCB in KiCad ...
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32 views

What does it imply when substrate terminal of Nmosfet is short-circuited with the source terminal? [on hold]

What does it imply when substrate terminal of N-MOSFET is short-circuited with the source terminal?
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31 views

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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59 views

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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39 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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75 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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Hspice dc analysis with op [on hold]

Is it possible to perform dc analysis and for all or some points get the working region of transistors?
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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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42 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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61 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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36 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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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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574 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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76 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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45 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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61 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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111 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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1answer
32 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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42 views

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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99 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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66 views

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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41 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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31 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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63 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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43 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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101 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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120 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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43 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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28 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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56 views

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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27 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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101 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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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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73 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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46 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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3answers
45 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
48 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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54 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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41 views

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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77 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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1answer
56 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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135 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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1answer
32 views

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 ?