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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22 views

Error in compensator for buck

I'm trying to put my ZVS buck converter (DCM) in closed loop. I ran some simulations on MATLAB, and figured that just multiplying the transfer function of the open loop buck by 0.5 gives acceptable ...
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53 views

Boost converter MOSFET shorting

I apologize in advance if this is a more common sense question - I'm still learning some of the basics and using this project partially to just build my knowledge. I've built this circuit with an ...
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Is the output resistance of the first amplifier the input resistance of the second amplifier?

If I cascade a MOSFET based amplifier with another one to form a multistage amplifier, then in small signal analysis, will the output resistance of first amplifier become the output resistance of ...
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Mosfet Protection Diode Part Number 3S4L VH10

Mosfet Protection Diode Part Number 3S4L VH10 I can not find it or anything like it. It has 2 leads like a diode, but uses a Mosfet. Very low voltage drop. I am using it for reverse voltage ...
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29 views

Single pulse generator using discrete components

I've a board like this: simulate this circuit – Schematic created using CircuitLab What I want to do is to drive LEDs with OUTPUT pin. This LEDs are used like flash source, so I turn them ON ...
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51 views

Large voltage drop across source terminal

I am using an N-channel MOSFET to enable another IC. My gate voltage=1V, the drain voltage=3.3V. After rigging up the circuit, the voltage across EN_DC23 was measured with reference to ground and it ...
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67 views

Backfeeding MCU gate output bad?

I am trying to modify a work light (1S3P 18650 3,6V) that is controlled by an 8 pin PADUK type micro. An output from the micro goes through a 100 Ohm resistor straight to the MOSFET gate. It has the ...
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41 views

TVS/Bidirectional Zener for N-MOSFET Gate Protection

I am using a MOSFET to read a square wave, which usually ranges between -1 and 16 V. However, on occasion, the signal can reach values of -30 to 45 V. My current setup uses a Zener-protected STN3N45K3 ...
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29 views

Gate noise on KA3525

I am designing a 1kHz inverter in a push-pull configuration with KA3525 and IRF540N MOSFETs. Input - 12V Output - 110Vac - square wave filtered to sine wave Power - 15W at 1000Hz When I fire it up ...
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23 views

Can I use 2 H-Bridge for drive a motor?

I've a 12V 80A motor, for drive this i'll use a H-bridge with mosfet, in order to divide the current per H bridge we can drive a motor with 2 H-bridge? I'll use mosfet, we cant put mosfet in parallel
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62 views

TO-247 case maximum current

I've this TO-247 MOSFET http://www.datasheet.es/PDF/203551/2SK3271-01-pdf.html how much current will support this case? I've to control a 12V 80A DC Motor
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93 views

Getting glitches on GPIO using a MOSFET as a logic level converter

I need to connect an Event Detection pin (pin of the NXP NTAG 5 component) to a GPIO of the NXP i.XM6 processor. The problem is that the NTAG 5 pin has a logic level of 5V and the GPIO has a logic ...
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63 views

High gate pin current leakage on a p channel mosfet

I have added a P-MOSFET before my main circuit, between the v+ of the battery, and the Vcc main power line of the circuit, so that the battery stays disconnected and doesn't drain until I am ready to ...
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29 views

Deviation in the switch current in a flyback converter

This is the current waveform of the switch and the Vds of the MOSFET. Ideally, the current should fall off in a normal fashion with the switch turns off. Here, the current fall stops and becomes flat ...
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77 views

Why are standalone MOSFETs and transistors preferred over integrated load switches?

As a novice to EE concepts who's trying to apply it to Arduino projects, I was doing hours of research on how to electronically switch another higher current (or voltage) device/component/subsystem on ...
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97 views

MOSFET getting hot. Is it normal?

I am using a Diodes AL8871Q IC to power a XHP70 LED at 3.4 A. My thermal cam shows the MOSFET at 108 degees C after 60 seconds with PWM control running at 40% duty. Is this expected? MOSFET I am using ...
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Is there a typical “Active Directivity” for LDMOS components?

Active Directivity is a measure of how much an amplifier's source match potentially affects its output impedance, or its load match affects its input impedance. High active directivity is a good thing....
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79 views

Redesigning MOSFET switches

Consider the two circuits below, the first is the original: When HIBERNATE goes high, it switches the MOSFETs Q1 and Q2. However, because of the 10 kΩ bias resistors built into BJT Q3, it pulls ...
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115 views

The voltage becomes zero when the load is connected [closed]

This is my circuit. When I connect the load of 10 Ohm, the voltage goes to zero! The voltage goes to zero even if I put resistor of 10 kOhm.
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Bi-Directional Logic Level converter 1.8V-5V using MOSFET

I need to connect an Event Detection pin (pin of the NXP NTAG 5 component) to a GPIO of the NXP i.XM6 processor. The problem is that the NTAG 5 pin has a logic level of 5V and the GPIO has a logic ...
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1answer
30 views

Bi-directional High Side Load Switch Design

I want to design a high side load switch which can allow or block DC current in either direction based on a 3.3V input. Some considerations: The 3.3V rail is potentially created as a result of power ...
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22 views

Negative voltage to the drain of NMOS

In NMOS, when, Vgs = Vth Vds < (Vgs - Vth = 0) so, Vds is -ve, so initially I thought in nmos, if Vds is -ve, Id direction ...
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51 views

Polarity switching circuit

I have a variable resistor as a load that want the current to remain constant by changing the voltage, This circuit also has polarity switching (like H-bridge). Each time the circuit is turned on, ...
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61 views

Generating Asymmetric AC PWM with MOSFETs

I have a tricky project that requires -10 V low, +40 V high, duty<0.5%, 2 kHz PWM. Load: 50Ohm resistive (forward),backward is probably in MOhm range. max power 1W (only works with very low duty). ...
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55 views

Arduino transistor switch

I'm building an Arduino switch for two different signals and I'd be very grateful if you can revise the schematic and tell me if there's something wrong or if something can be improved. In the ...
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Blocking oscillator/slayer exciter with autotransformer?

So I was making a slayer exciter and I was fiddling with primary to secondary coupling when I got this idea: Tesla coil secondary is a quarter wave resonator, and a device called "Oudin coil"...
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How to drive a high side MOSFET with an optocoupler correctly?

I am trying to create an absolutely minimal motor driver, to create a <5$ low power odrive. But since I am only a software developer, I do not have a 100% understanding of analog components, and ...
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44 views

reverse polarity protection using alternative configuration

it is a typical diagram of reverse voltage protection using N channel MOSFET. what one should do is to connect the anode to the source of the MOSFET. But here instead of that I have connected to the ...
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30 views

Choice of mosfet transistor for linear operation (voltage controlled dummy load / current source)

BACKGROUND I have built very simple dummy load to test thermal behavior of some switching power supply (5V 5A). Vbat is 8-9V from 6F22 battery. Resistors are oversized to reduce working temperature. ...
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64 views

Can two IRLZ44N MOSFETs in parallel handle a current of 20 A without heat sink?

Can two IRLZ44N MOSFETs in parallel handle a current of 20 A without a heat sink? The Vgs command is a square wave at a frequency of 70 Hz. Do I need to attach two big heat sinks or not? Will my two ...
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39 views

Calculation MOSFET max current needed for PCB + pulldown calculation?

I would like to know if there is a calculation that allows me to look up at how much current my PCB would draw in the worse-case scenario if all my MOSFETs would have to change at the same time. In ...
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57 views

Why MOSFET switching load effect gate voltage?

I use this Chinese MOSFET module to drive mini DC pump using control signal from Arduino (simply on off with blibk sketch) I know that we need to add flywheel diode but it this case unfortunately, it'...
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48 views

Control 12v relay in series with 3.3v

I would need to control 4 relays (300 mA each) with an esp32. Relay will open and close at the same time so i not need a dedicated control. As I'm not expert I would like to ask you if you can propose ...
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Why does the output of the mosfet differential pair connect to the gate of the pmos of a common source amplifier?

I'm told that a simple operational amplifier made from MOSFETs can be shown in the picture below. M1 M2 M6 and M7 make a differential amplifier. M3 is used as the reference mosfet to create a current ...
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65 views

Short circuit current determination in MOSFET [closed]

Can anyone please help me solve this problem: A test needs to be performed in order to know if the MOSFET that is opening and closing the battery power delivery will sustain a short circuit current. a....
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29 views

No output for N-Channel MOSFET on PWM on STM32F0

I am using dual N-Channel MOSFET FS8205A, following is a screenshot from its datasheet. and the following is the schematic I am using in my project. The Gate is also pulled down to the ground with a ...
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28 views

IV characteristics of NMOS transitor

I have used the model of the GPDK90 transitor in Cadence. I have few questions regarding the IV characteristics: Why does the threshold voltage change with change with Vds (Vds= 0, 1.25, 2.5, 3.75 ...
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51 views

MOSFETs in push-pull configuration: possible short circuit during transition?

I have created a test schema since I received a late response that I might be short circuiting my own push-pull setup in this post Offsetting Op-Amp output offset in combination with charge pump. It ...
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MOSFET triode small-signal modeling

TL;DR: Why do seemingly all treatments of MOSFET small-signal operation ignore the nonzero \$g_m\$ contribution in triode? Is the implicit assumption here that if the MOSFET is operated in triode then ...
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Negative gate transients on high side half bridge FET

I am trying to simulate a half bridge for a 3 phase motor driver. When my high side FET transitions off, during the dead time, the switch node voltage is 25V. I would expect this voltage to be a ...
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59 views

H-bridge made of MOSFETs

If we have an H-bridge made of 4 N-MOSFETs, the gate voltage applied to each pair must be different because in an active circuit the sources will have different voltages. How much?
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46 views

MOSFET Switching Loss Formula

I'm trying to calculate the switching loss of the MOSFET which is used for a DC-DC Boost converter. Input Voltage : 9V-16V Output Voltage : 30V Output Current : 0.3A. Switching Freq : 455kHz Based on ...
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99 views

How can I decrease power losses of H-bridge with 4 N-channel MOSFETs?

This is my H-bridge circuit. I need to change the polarity and found this circuit from the site. I need 0-200 amperes for the load. I want to use the IRF1404 and parallel them, but I have two problems:...
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107 views

How does this simple circuit work?

I'm trying to create a project but I'm stuck somewhere. I decided to put a small portion into a simulator and it seems like the MOSFET is able to turn on and electrons can flow from the second diode. ...
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32 views

How can I increment PWM resolution for PMSM FOC control?

The pwm resolution effect torque ripple value. My motor should be turn low speed . When the motor is turning slowly , the effect can be seen barely. I have 1024 pulse encoder per tour . The hardware ...
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79 views

How to switch “best” between two voltage sources (5V & 3V3) for a single output (“MUX for VCC”)?

How to switch best between two voltage sources (5V & 3V3) for a "load" (e.g. a sensor in the application field or Arduino/Raspberry Pi/etc.). The basic setup is as follows: there are two ...
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How to Find the Thermal Resistance Junction to Ambient

I have this BUK9M12-60E MOSFET. I have calculated the maximum power dissipation of the MOSFET to be 14W (Conduction loss, Switching Loss and Gate Loss). I believe that I don't require any heatsink. I'...
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204 views

Will this circuit manage to kill a 2-stroke engine?

I'm currently building a project that involves a 2-stroke engine. I have tapped into the wires where you would normally place a kill switch in order to get power for some electronics. The voltage is ...
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25 views

PFC formula for calculating conduction losses across MOSFET

I am not able to demonstrate the formula above where Vin is the input voltage of the PFC, Vout is the output voltage, Po is the output power, and Rds(on) is the on resistance of the mosfet. This ...
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707 views

Why are all the MOSFETs' drains connected together and to nowhere else?

I was studying the schematic for the "Waveshare UPS HAT", just because I am a beginner and find it educational. This part is really confusing for me: Why are all the drains of those AO4406A ...

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