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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3answers
68 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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85 views

Mosfet Driver - High Side Output Problem

I've been trying to make a 3 phase inverter to drive a BLDC motor. Mosfets : IRF3205 Driver : IR2101 Supply voltage for FETs and drivers : 12V BLDC : https://media.digikey.com/pdf/Data%20Sheets/...
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57 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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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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1answer
89 views

Using DC generator as power source and switch in multi

I have the following: DC Generator 5V regulator lipo charger (5v input), 3.3v regulator, lipo battery device requiring 3.3v power I only want the battery to be connected to the 3.3 regulator (and ...
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1answer
104 views

High Vds across MOSFET in saturation mode in Flyback converter during simulation

While simulating a flyback converter, I find that even in saturation mode the MOSFET, in spite of having Rds(on) around 0.74 ohms and the Ids = 5.75mA, is dropping almost the entire drain supply input ...
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1answer
39 views

Freewheeling diode position

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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1answer
97 views

5V digital output to 24V

I'm sure it is a simple solution but I am new to this so please take it easy. I need to come up with something to convert a 5V digital output signal from a USB-1608G DAQ device with DIO to 24V ...
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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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2answers
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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1answer
188 views

Finding Kn from ID vs VDS graph

I have the following simple circuit to obtain characteristics of an N type MOSFET. The gate voltage will be swept from 3 to 6 Volts while the drain voltage will be swept from 0 to 0.5 Volts to ...
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129 views

MOSFET analog switch, Transmission Gate, Bilateral switch circuit questions

Below is an LTSpice simulation of two attempts at a Mosfet bilateral switch or 'transmission gate'. The plot shows the switch (onoff) going from 0 to 5v (in blue) and a sine wave audio signal being ...
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15 views

Hspice dc analysis with op

Is it possible to perform dc analysis and for all or some points get the working region of transistors?
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1answer
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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1answer
76 views

Cash drawer working , if possible schematic [closed]

Can anyone tell me as to how the cash drawer works? A schematic would be helpful too if anyone can find it! This circuit will work after adjusting the resistance and adding diode for reverse current.
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106 views

Need to determine a mosfet, and wouldn’t mind a little education in the process

I want to start off by saying that I am a complete electronics newb. I know a little but am always looking to learn more. With that said I am asking for a little help and a little learning. Here’s ...
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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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2answers
261 views

Reducing effect of MOSFET parasitic capacitance with resistor in series with gate

I have a MOSFET in series with the output of my amplifier to switch the amplifier output to the downstream circuitry. The MOSFET parasitic capacitance is seen as a load capacitance by my amplifier, ...
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1answer
124 views

How do actively driven mosfets or transistors react to floating source?

Attempting to add some lights to a car's "intelligent" lighting system. Want to make sure I understand how my n-channel mosfets will react to losing their ground, while their gates are still connected....
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35 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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169 views

Why Arduino does not suit the to trigger a Spark plug but 555 timer can?

To trigger a spark plug and to control it using an Arduino, I tried following this really well-written guide. Basically, a MOSFET(IRF540N in my case) controls the closing and opening of the primary ...
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79 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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1answer
92 views

high side driver failure

I am having 100% failure rate trying to get this high side driver to operate. The failure happens as soon as the 5v logic signal is turned on. I have had straight shorts from VDD to GND, and I have ...
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2answers
119 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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2answers
571 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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138 views

Using a p channel mosfet to switch a RF switch

I'm very new to electronics, i have the following RF switch (CG2179M2) which i need to control using the output signal of my MCU, which will provide a 3.3V HIGH for transmit mode and LOW for ...
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1answer
75 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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1answer
107 views

How to make a bidirectional power switch for negative supply rail controlled from logic level MCU

I'm looking to build a bidirectional power switch for a negative power rail. I have a +12V, +5V, +3V3 and -5V supply to switch. For the positive supplies, I'm using two P-channel mosfets in a common ...
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4answers
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
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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1answer
3k views

MOSFET in reverse polarity protection

I have such a reverse polarity protection circuit for the power supply: The MOSFET used has a maximum VGS of 10 V, so that's why there's a Zener diode of 7.5 V. But what happens if I ...
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1answer
106 views

Questions from a current regulating and measuring circuit

In my previous question I asked about a simple topology suggestions for regulation of highish currents(around 10A) especially for resistive heating elements in 1...10 Ohm range. I concluded to use a ...
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1answer
31 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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98 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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3answers
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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1answer
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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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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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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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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1answer
125 views

rfp30n06le MOSFET not outputting current

I have a rfp30n06le (N channel MOSFET) that I'm trying to power a brushed motor with. The source is connected to ground of a 1 cell lipo battery. The drain is connected to the negative side of the ...
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2answers
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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3k views

PIR sensor led strip with N channel mosftet

I have a PIR sensor (HC-SR501) and I want it to turn an led strip(12V 0.8A) on when the sensor detects motion and off when there's no motion. I checked a previous thread which is similar in that ...
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100 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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1answer
124 views

Raspberry Pi power switch preventing gnd from HDMI

I got a problem with my Raspberry Pi setup. I'm currently using an arduino to control an IRL520N to switch GND on and off on the rasperry and that works great, or it did... My setup also includes an ...
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1answer
100 views

Channel shape of NMOS in saturation

According to the Sedra/Smith Microelectronic Circuits textbook, 6/7 eds., increasing \$v_{DS}\$ beyond \$v_{OV}\$ has no effect on the channel shape and charge. Why is that? It seems as if (...
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518 views

Speeding up turn-on and off with VOM1271 Photovoltaic MOSFET Driver (/optocoupler)

It's my first post here so please do not hesitate to tell me if I'm not doing it right :-) A bit of context : we need to switch an array of power resistors (1,3kW, 1ohms) in order to test under load ...
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1answer
151 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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25 views

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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2answers
264 views

Limiting inrush current in N Channel MOSFET power switch

I have a N-MOSFET as power switch like this: I want to add a fuse on the power line but I have few capacitors on the across the load and I am worried that the inrush current might blow the fuse off....