Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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)

0
votes
0answers
7 views

two stage open loop comparator question

I am trying to understand the operation of a two stage open loop comparator. simulate this circuit – Schematic created using CircuitLab What is shown is the output stage, current-sink inverter....
1
vote
0answers
23 views

High side mosfet-driver circuit configuration for current bypass

I'm designing a current bypass bms and having trouble switch mosfets between calls When i connect the high side gate drivers and simulate with Proteus the overall voltage appears at the topmost cell ...
3
votes
0answers
45 views

Frequency Divider Analog Circuit issue

I am trying to implement a divide-by-two circuit quoted from the book "Low power CMOS circuits : technology logic design and CAD tools" by Christian Piguet Could anyone advise about the spice error "...
0
votes
1answer
45 views

Mosfet pinchoff, why the n-channel moves towards source?

Suppose we have an NMOS transistor with VGS> VT. When VDS is 0, the channel depth is uniform along the transistor. However, when we increase VDS, the channel becames deeper near the source and ...
1
vote
1answer
46 views

Linear Regulation Concept Confusion

I was watching one of Jacob Baker's videos (http://cmosedu.com/videos/f10/ece5472/lec1_ece5472_video/lec1_ece5472_video.html) At minute 19:30, he explains the concept behind linear regulation: His ...
0
votes
1answer
59 views

Why does the current in MOSFET have a quadratic function (explain logically without using the integration method)?

The current equation relating Vds ,Vgs and Vt is already known to us ,but if there is any way we can find out how it varies quadratically without using the formulae?
1
vote
1answer
88 views

Why does adding a capacitor greatly improve this circuit?

I've been prototyping this pretty simple circuit for a while now: simulate this circuit – Schematic created using CircuitLab Description: C3 is charged to set point. Compatator out put goes ...
0
votes
0answers
30 views

Induction Heater Problem [on hold]

In this simple schematic found here, it shows 2 MOSFETs. One of them seems to be flipped over. It appears to be asking me to connect the source of the top one to the drain of the bottom one. Or is ...
1
vote
1answer
91 views

Matrix of small incandescent lightbulbs - problem with buzzing

I am prototyping a circuit for controlling matrix display of small incandescent lamps with Arduino (each lamp is 6.3V 0.3A). I designed the circuit in Yenka and built it. It is composed from 3 types ...
2
votes
4answers
380 views

N-Channel Mosfet as Switch

I have a few n-channel MOSFETs (the irlb8721's) and I was able to use it as a switch to control an led with the gate at 5 volts. I would like to change the source/drain voltage to 11.1v from 5v and ...
0
votes
1answer
24 views

Parasitic source and gate inductance of SiC MOSFETs

I have a question about a tutorial video from PSIM: https://www.youtube.com/watch?v=iATO3mUKBPc In this video, a MOSFET circuit is created using LTSpice .lib files from Cree. The parasitic drain and ...
1
vote
2answers
67 views

Understanding mosfet drive voltage

I am planning to work with this N-mosfet - SiSA72DN Max ratings: Specs: Does this mean: I need to apply a voltage > 2.4 V on the gate to turn it on fully and the applied voltage must be < 20 V? ...
0
votes
1answer
13 views

Esp8226 with opto mosfet switch LBA110

I want to switch AC load by LBA110 because it has NC switch pole and tiny side. I tried to read datasheet, but with my bad knowledge about electric, I can not find out how to make it work. Is it work ...
1
vote
1answer
37 views

Mosfet testing for short from youtube repair video

In the 23:40 of the youtube video https://youtu.be/YQ7SXJqIpzs , the presenter does a p-channel mosfet test for short, using his bench power supply on the circuit. From what i understood, he ...
1
vote
4answers
69 views

P-Channel MOSFET Flipped on Schematic

I'm designing a circuit which has a bluefruit nrf52832 micro controller built into it. When referencing the schematic provided by Adafruit I noticed that they had +VBAT going to the drain of the p-...
0
votes
1answer
101 views

What are these two components ? I can't identify them

I'm having a hard time finding what these two components are.i can't find them anywhere. The first one is 3 leg MOSFET which has PDB marking on it and DD on the silkscreen The second one i can't ...
2
votes
0answers
52 views

MOSFET switching on

I have a doubt. Consider an N-MOSFET: which is the voltage that can switch on it? The voltage between Gate and? Sometimes I read "between Gate and Bulk", sometimes "between Gate and Source", sometimes ...
0
votes
1answer
73 views

Comparator loses voltage when connected to mosfet

I want to make a discharger for 18650 batteries so I can store them at a specific voltage. I built a comparator (LM393) with a voltage reference to 3.8V at the inverting input and the voltage of the ...
0
votes
2answers
72 views

Cheap alternative to limit inrush current (eg. relay bypassing a fixed resistor or MOSFET)

I'm editing the question because several (great) answers focus on the fact that the LTC3780 module (inside ajustable my power supply) can handle the inrush current (maybe, maybe not). I'm glad to know,...
1
vote
2answers
61 views

Can I do KVL around transistors? (MOSFET and BJT)

I'm having a lot of trouble with more complex transistor DC circuits (can't wait for the AC, heh). Basically, what I want to ask is does KVL holds "around" a transistor as well? For example, if I ...
0
votes
0answers
50 views

pwm RC filter question

I'm new here but been playing with electronics for a while now. I have this project where I'd need to read pwm controlled signal from mosfet. This is how stock application controls pwm valve: I want ...
0
votes
0answers
20 views

Does my PWM led circuit controlled with NodeMCU and Mosfet work properly. What should I do to improve it? How to calculate for each components?

If I understand it right, when there's is signal from ESP, the PNP and NPN be ON, and Vgs=0. If they're OFF Vgs=+12V and the LED will shine. R=1K is to limit the Ib of NPN, and R=10K is the resistor ...
0
votes
0answers
28 views

How to calculate R1 and R2,? How do Mosfet IRF540 and ESP work in the circuit

So the 3.3V PWM signal from ESP is sent through R2 to the Gate to breakthourgh the Vgs(th) to make Mosfet ON, and the author of the circuit say Gate is pulled high to 12V by R1. But I don't understand ...
3
votes
1answer
132 views

Is there any advantage to using multiple tracks in this PCB design?

I'm fairly new to PCB designing, but I'm loving experimenting with it. Currently, I'm trying to develop a simple PWM circuit using MOSFETs to control an RGBW strip, using an Arduino with an integrated ...
1
vote
2answers
40 views

Understanding Mosfet Circuit with PWM

I am wanting to control a voltage range of 0-10v across a 10k load with PWM from a micro. Now I was told to use this circuit with an n channel mosfet: This is what I understand so far: R1 is to ...
1
vote
0answers
33 views

BeagleBone Black Driving NFETs w/GPIO

In short, I want to drive some NFETs directly from some of the BBB's GPIO. 3 of the NFETs will pass 1-3 Amps of D-S current and 1 NFET will pass <1 Amp from the D-S. As you may know the BBB's ...
-1
votes
2answers
49 views

trying to figure out the differences between the six transistors provided by the schematic tool [closed]

My background consists of a BS in Computer Science and an MS in Computer Science and Engineering, both from the University of Washington. My MS consisted mostly in the very high level design of a ...
4
votes
3answers
852 views

Resistor Selection to retain same brightness in LED PWM circuit

I am making a simple LED PWM brightness control circuit. I am using a relatively high power White CREE LED, N-channel Enhancement MOSFET BSS316N and Resistor R. The circuit is as shown below. I am ...
0
votes
1answer
46 views

Designing a circuit using an LT1073 DC-DC Converter

I'm currently designing a circuit to convert a 24V (±30%) to supply a 3,3V IC used to monitor currents. I need to use the LT1073 which has the following diagram. The operations of the component and ...
0
votes
1answer
43 views

Testing 8 pin P-Channel MOSFETS on Laptop Motherboard

My laptop died recently and I’m testing the motherboard. I’m led to believe these two MOFSETs on the board may be part of the issue PQ301 and PQ302. Using a multimeter continuity and diode mode; ...
1
vote
1answer
47 views

Single MOSFET current source (JFET like)

Is it possible to build MOSFET current source similar to JFET current source like this: simulate this circuit – Schematic created using CircuitLab With MOSFET it should be something like this: ...
-1
votes
1answer
32 views

MOSFET switch, ATtiny10, Raspberry Pi

I had posted a question earlier but I was using a BJT at the time and the solution provided led me to use a MOSFET for my application instead. I switched to the FET but still unable to provide stable ...
0
votes
3answers
64 views

ON-OFF MOSFET Switch for Induction Heater

The induction heater was tested using a relay as an ON-OFF switch before and worked so i just want to focus on the MOSFET switch part of the schematic. When i tested the circuit using a MOSFET switch ...
15
votes
3answers
1k views

Why are BJTs common in output stages of power amplifiers?

From my understanding, the role of the output stage is to decrease the output impedance to almost 0. For that, MOSFETs seem better suited since they've got way lower \$R_{ds}\$. Yet I see quite often ...
1
vote
1answer
40 views

High current, high frequency IC PWM switching with MOSFETs

I'm designing a circuit for an automotive application (chassis ground) that has a number of MOSFET outputs to drive large LED arrays and smaller motors (application tends to favour non inductive modes,...
0
votes
0answers
39 views

Problem with MAX1645B test circuit?

Please consider the schematic: The MAX1645B is a level 2 battery charger. My problem is with the P-Channel MOSFETs. There are two P-Channel MOSFETs in the above circuit. From the datasheet: ...
0
votes
1answer
69 views

How do I drive a MOSFET when I have an 11.1v power-supply and an arduino [duplicate]

I am trying to use a irlb3034 as a switch to power an airsoft motor and control it with an arduino. I am using a diode between the source and the drain and a 2.2k resistor between the gate and the ...
1
vote
2answers
107 views

Using Mosfet with seperate Logic Converter and Arduino

I am trying to use an IRLB3034 with an Arduino even though it is not a logic level MOSFET. I am planning on using an LM2937 12v regulator like the schematic below: The connection going off the page ...
1
vote
2answers
59 views

Correctly using MOSFETs

I'm using a P-Channel (DMP1045UQ) and an N-Channel (BSS138K) FET to pull a 12v Logic line (12v @ 5mA) high (from GND) from a Logic Level(3.3v) MCU I/O pin. Here is the schematic, where ...
0
votes
1answer
24 views

Voltage or Current Control with a Microcontroller for Pressure Regulator

I am wanting to control the flow rate of a pressure regulator (https://www.festo.com/net/SupportPortal/Files/505126/VEAB_2018-05a_8080669g1.pdf). My idea is to control this with a PWM signal 0-5v. ...
0
votes
2answers
70 views

Forward diode characteristics not starting from zero Ampere

Why the current is not starting from zero, whats the diode characteristic when current is near zero? Reading the datasheet for N-channel 60V MOSFET, I encountered this source-drain characteristic of ...
0
votes
1answer
56 views

How to calculate gate charge time for a mosfet?

I am designing the circuit shown above using mosfet NDS355AN. MCU is 5 V. However, I have become stuck as I am unsure of how to calculate the gate charge time of the mosfet. Hence what is the formula ...
0
votes
0answers
30 views

What test points to do for a switching system measurements?

I am working on a high-performance switching system. I the old ones there was no big issue in just touching a gate with an oscilloscope probe, but this time I have high voltage and very short (5nsec) ...
0
votes
2answers
85 views

If a short circuit occured across the mosfet would anything happen in this scenario?

I am just confused about understanding a simple concept. For the following circuit: Say the blue line acts as a short for whatever reason. If the LED has a forward voltage drop of 23 V and forward ...
0
votes
0answers
53 views

IRF3205 switching problem

I bought a power mosfet(IRF3205) and tried to switch but mosfet is not behaving as I expected when gate pin is triggered it doesnt change its position. Below is how my schematic looks like, I could ...
4
votes
0answers
138 views

How to identify SMD device marked LEFBV?

I have a SOT23-3 component marked \$\underline{\textrm{L}}\,\underline{\textrm{E}}\,\overline{\textrm{F}}\,\overline{\textrm{B}}\,\textrm{V}\$ as shown in the following images: The following ...
0
votes
2answers
42 views

MOSFET Controled Relay Problem

As a way to power-on/-off a circuit load, a MCU is used to drive a relay through two MOSFETs. The problem is, when the MCU GPIO output is measured 0-volt, the relay could stay connected. Can anybody ...
0
votes
1answer
40 views

How to find the Common Mode Rejection Ratio of this circuit?

My attempt was like, by using the formula, I can get, \$CMMR=\frac{\sqrt{2\cdot4\cdot8\cdot5\cdot10^{-6}}\cdot44000\cdot2}{x}\$ For the denominator, I used both 10% and 20%, but all the finals were ...
3
votes
1answer
70 views

Constant-gm bias circuit

I am doing a study on Improvements in biasing and compensation of CMOS opamp. Do you guys know how to come up with the equation for RDS4C ?
-1
votes
0answers
73 views

Mosfet not turning off when gate is grounded

I have a FQP50n10 mosfet which I used to drive an Arduino and it was working great. For the past few months I've been trying to make a circuit but it’s not working with the values I want because I’m ...