# 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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### 2 E-Mosfets connected in series calculations [closed]

So suppose we have two E-MOSFETS connected in series across a 10V supply, and the upper MOSFET has its drain connected to the gate, and the lower one is unbiased. (The input is taken to be the gate of ...
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### p mosfet calculations reverse polarity for high power ( 48 V , 30 A )

i want to make reverse polarity protection for input 48 voltage , load 30 Ampere 2 dc buck converters. i was searching many solutions like diodes , but i wanna make it with p fet , so i came across ...
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### MOSFET Gate voltage

I have a series resonant circuit where I will have a lot of capacitors. I want to select a capacitor value for resonance for a particular frequency and want to turn on that capacitor using a MOSFET. ...
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### Rs and Rd in series in MOSFET circuit?

Can we consider Rs and Rd to be in series? That is, is the equation ID = (Vdd)/(Rd+Rs) correct? What is confusing me is that they have the same current, but there's a voltage drop across the drain-...
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### Switch that turns on and off as voltage changes

I want to control a 12 Vdc, 2 A fan. I'm connecting it to a battery bank in a sailboat. I want to turn on the fan when the voltage reaches 14 Vdc. When the charger turns off, the battery voltage will ...
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### Turn off and turn in time of Mosfet

Why mosfet have different turn on and turn off time? If I am correct, mosfet have higher turn off time. Why?
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### 65V Square wave Switching Circuit

I am trying to generate a 65V square wave very similar to the post found here: Mosfet PWM signal not square My load is in a slightly different configuration (i've tried them both ways), but the ...
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### LED driver: how to choose current and voltage?

In my project I have a microcontroller which has to light 3 groups of LED. Group A has 3 LED, Group B has 2 LED, Group C has 1 LED. There are all the same LED. In each group the LED are in series. ...
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### 6T SRAM write operation calculations

C: Cut off , L: Linear , S : Saturation [keep in mind I am teaching this to myself ahead of time] I understand how to go about finding desired ratio (W/L) for read operation. In the image, M1 would ...
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### Wireless power transfer circuit to attain ~5W of power on the receiving end

I am designing a WPT system to run a ws1812 based pixel chain. The ws2812 pixel chain runs on 5v and consumes 500-800ma of power, means 2.5w-4w. The system I made is not able to transfer adequate ...
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### How to prevent reverse current/voltage on a sense line?

I'm designing a rocket launch controller, that incorporates an Arduino to provide a safer and more controlled launch. Original rocket launch controllers used to use an incandescent light bulb and a ...
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### Why are diodes a fundamental part of a MOSFET [duplicate]

I noticed that there are diodes inside a N-Channel Mosfet. I am curious as to a simple explanation of what the diode does exactly?
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### Is the switching speed of MOSFET comparable to that of a Schottky diode?

Assuming identical voltage and current rating, which is having higher switching speed? MOSFET or Schottky diode? In synchronous buck converter, we replace Schottky diode with MOSFET (low side) for ...
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### Is it possible to implement a high-side current mirror with only NMOS FETs?

I need to implement a difference amplifier only using NMOS technology. I am struggling when trying to reference the voltage difference to ground. From my reading it looks like I need a high-side ...
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### Arduino RGBW 24v LED strip driver

This might not even be the right place for me to ask, but I hope somebody can help; I have an arduino mega with 4 PWM outputs (5v, fitted with 220 ohm resistor) that I would like to use to control ...
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### How to choose the correct N channel Enhancement MOSFETs?

Having little to no experience on MOSFETS i am having trouble part sourcing the correct one, one that will work for my applications. But before i go with the terms let me show the circuit first ...
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### Is Vout in this circuit loop-grounded when Vin becomes 0V?

I don't have expertise in this area. So any answer or instruction would be helpful to relieve my pain. I think Vout would lose its GND when Vin becomes '0V' because C is located before GND. Am I ...
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### ZXM61N03FTA as a replacement for Si1308EDL

I'm working on a e-Paper display driver. The reference design uses Si1308EDL as part of the boost converter. I'm sourcing the components from LCSC, but unfortunately Si1308EDL is not in their stock. I ...
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### Dual MOSFET Switch Circuit not switching

I'm trying to switch a high-current, 12V load (large parallel LED strip, with the anode connected to LOAD-) using a PWM chip. My approach right now is to use a ...
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### Designing an over discharge lithium ion protection circuit

I am trying to build a portable RGB LED display that runs off a Lithium Ion battery. After a few days of research, I understand the importance of using a dedicated IC to handle charging the battery, ...
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### Turn-on and turn-off switching energy

Is it possible to calculate the turn-on and turn-off energy of SiC-MOSFETs with datasheet parameters? The method with Ā½ * U * I * tr (or tf) cannot be used here. Let us take the C2M0080120D from Cree ...
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### Making a more efficient replacement for my diode

I am making a boost converter using the LM3481 IC (although it might be considered a sepic topology as well). Typically in a boost topology, you put a diode before the output capacitors so they don't ...
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### Would this shift register schematic avoid master/slave if I extended it to four billion bits? [duplicate]

simulate this circuit – Schematic created using CircuitLab The basic data structure for the machine I want to build is a shift register. Quite some time back someone told me that if I could ...
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### Parasitic Inductance - DPT circuit

I have a question about parasitic inductances. Let's take the figure below as an example, a DPT circuit is shown here. I have added an inductor (parasitic loop inductance). I would like to have a ...
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### How do I solve the input resistance of this BJT and MOSFET in series?

This is a sedra-smith microelectronics excercise question for which I can not find the answer and I hoped for perhaps a solution here?
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### How to get the gain for this MOSFET amplifier?

This is a common drain MOSFET amplifier: simulate this circuit – Schematic created using CircuitLab This is its small signal model at low frequency: simulate this circuit I am at a loss as ...
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### What is wrong with this circuit simulated in Proteus?

When simulating this circuit in Proteus, I expect the LED to light up when the switch is closed, but it does not light up. What am I doing wrong?
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### Parking Light And Signal light with same LED using MOSFETS

I have a project where I have an existing 12v parking light and I want to also have the turn signal use the same light. I've constructed a circuit using 2x NMOS and 1x PMOS. I think it will work and ...
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### high current passing through mosfet is damaging the nrf52

simulate this circuit – Schematic created using CircuitLab recently trying to make a led strip that can be controlled over bluetooth. I need high currents up to 10A. for the test purposes I ...
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### MOSFET simulation model

I am trying to model a synchronous buck converter, for which I need to choose mosfet models for simulations. I am seeing that it has various parameters out of which length and width is affecting the ...
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### Where is the voltage drop? / How can I test circuit this without using an actual battery?

I've put together the following circuit, it's just a rechargable LED torch, just to try load sharing: simulate this circuit – Schematic created using CircuitLab BAT1 is a LiPo battery, 5.2 V ...
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### IRF7821: is one of them fake?

Left looks like genuine (logo), right looks like fake. Is it, really? Edit: this part is expected to be IRF7821.
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### MOSFET Triggers with Electrostatic Energy

In the attached circuit with a 5V relay and a 30V load across it, I've noticed the FQP30N06L MOSFET triggers with even electrostatic energy (touching the gate). The difference between the circuit ...
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### Gate Current Calculation and Practical Mosfet Selection

Vnoo3 is the drive voltage, and Ig is the gate current. What I am wondering is: 1) How to calculate the peak Ig on the rising edge of the pulsed gate voltage? For instance, using the spice image ...
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### NMOS Switch, Drain Source Location

I just have a bit of confusion about which way to orient MOSFETs in IC switches for sample and hold circuits Which one is it? Or does it not matter?, since the Source and Drain potentials will be ...
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### Power Gain in a Small Signal Mosfet Circuit

let's consider this circuit, which is the equivalent of a small signal Mosfet amplifier. where RG is a gate series resistance which takes into account of the oxide leakage, and CGS and CGD are the ...
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### Isolating grounded resistance? Glow plug thru MOSFET

Have an Arduino triggering an LED array AND a MOSFET that burns a glow plug for 1 second, from the same power supply (3.7V 720mAh Lipo). The issue is that when the mosfet is triggered, it seems to ...
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### Short Channel MOSFET model

I was reading on a book (Thomas Lee, The Design of CMOS Radio Frequency Integrated Circuits) that in a short channel model, since the phenomenon of drift speed saturation is very relevant, it is a ...
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### Need help for using N-Mosfets to switch on either one battery or the other

I'd like to add a second battery (36V Li-ion) to an ebike to increase its range. My goal is to use one battery at a time, not using both in parallel with e.g. ideal diodes or something. I'd like to ...
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### Finding node voltages in a MOSFET circuit

simulate this circuit – Schematic created using CircuitLab Considering Vdd=5v I want to calculate the node voltages at P,Q and R.
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### Back-to-Back PMOS high power dissipation

I have created a circuit in LTspice to switch between two power sources (10s Li-Ion batteries). V1 and V3 resemble the power sources which vary from 30-42V. V2 and V3 are output pins of an ĀµC. R3 is ...
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### Automotive High Side Switch vs. E-Fuse

I've been looking for a solution to provide solid-state overcurrent protection for automotive loads such as small water pumps (0.6A continuous), fans (3.5A continuous) and fuel pump (8A continuous). ...
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### How to select a MOSFET when using 3.3v / 5v Logic level [duplicate]

I want to control/dim a 12V LED strip. When using an Arduino, I used a MOSFET IRLZ44N, and a 12V DC adapter - it works as needed. I wish to use same hardware to control it remotely; a Wemos Mini is ...
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### MOSFET Driver increase maximum duty cycle

I have a piece of test gear I am working on designing, in which there I need to drive a number of N channel mosfets, (3 high side, 2 low side) I found there is a very large range of gate drivers ...
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### Is isolation required for MOSfet gate driver's and microprocessor's power supply?

I have designed a 62W , 24V-5V buck converter operating at 250KHz. I am using TI's UCC27200A gate driver and Infineon's Optimos 4. The problem is that the driver doesn't have any kind of isolation ...
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### Half H-Bridge Control

I need to control a Half H-Bridge circuit to move a DC motor on both clkwise and ctrclkwise directions. I've tested the following circuit: It worked as it was supposed to: when the digital input ...
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### How to prevent capacitive discharge on my load after MOSFET off state

I built a button on off latch circuit using nand Gates then connected latched output to Nmosfet's gate with a resistor. My load is a smps circuit drives the power Led and this circuit has emc filter ...
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### MOSFETs Cascode Configuration

The following schematic is from Texas Instruments: http://www.ti.com/tool/PMP10195 I have some questions on it: Is Q1 always on? How do I calculate the voltage that the gate sees? It looks like this ...