All Questions
Tagged with switch-mode-power-supply mosfet
161 questions
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Controlling a spark plug using 555 IC
I built a circuit for ignition system using MOSFET, 555, ignition coil (specs unknown, but current rating is more than 2 A and less than 10 A), SMPS (12 V, 10 A for powering the the whole circuit.)
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1
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672
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why MOSFET Driver [closed]
Why do we youse MOSFET Driver when we use MOSFET as a switch in a high side configuration and we do not use it in low side configuration?
Can we drive a MOSFET ON/OFF with the OUTPUT of UC3842?
- 1,078
2
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1
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SMPS test circuit PWM controller not switching the MOSFET
Trying my fingers on a very old SMPS circuit (15+ years) section.
The open loop test circuit generates 25 kHz pulse train (12 V - 0 V) with 50% duty cycle as designed in the actual SMPS circuit. ...
- 175
0
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1
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954
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SMPS typical drain current when MOSFET goes to saturation
Here an old smps circuit which is very similar to mine. But the gate driving voltage seems to be very high in my opinion.
Q1. If the gate threshold of the MOSFET is 2-4V , will the 12-15V pulse train ...
- 391
2
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3
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371
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High Vds across MOSFET in saturation mode in flyback converter during simulation [closed]
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 ...
- 391
1
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1
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588
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Push-pull MOSFET gate schematic
So I was looking through the MAX713 datasheet and came across the schematic below. In short, MAX713 is a NiCd battery charging IC and below is shown the schematic for it in the the switching mode. The ...
- 1,177
3
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3
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Choosing the correct Gate Driver for a MOSFET in a DC-to-DC Converter
I am building my first simple buck converter, stepping down 12 V to 5 V and driving a small load of 5 Ω - 10 Ω. Something like the following:
or:
The above images both show an N-channel MOSFET. I am ...
- 1,191
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1
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Why is there a gate-source short on the n-channel mosfet? (circuit attached)
I am having a problem with the circuit below.
I am trying to use the IRLR8726TRPBF to switch a 24V pump by turning the Gate HIGH and LOW using the Arduino. However, there when I connect power to the ...
- 17
2
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3
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815
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Can GaN FETs be driven directly by logic level signals?
I've gotten interested in using GaN FETs for their combination of fast switching speed and very low on-state resistance. Most of the eval boards (for example by EPC) use GaN driver chips such as ...
- 3,541
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1
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Driving a MOSFET with Negative Off- State Gate Voltage
I know in practice Mosfet switches are driven by 0V to any Positive gate voltage (e.g. 0V - 15V). I am using a Mosfet pair (PMOS and NMOS) to switch 10A currents in pulses and the datasheet of MOSFET ...
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1
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P-channel mosfet as power switch
I have some questions about this circuit (from the book 'Art of Electronics'):
How can this P-channel mosfet support high source voltage (150 V)? In the datasheet it's mentioned that \$V_{gs}\$ = +- ...
- 355
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1
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MOSFET Based Current Limiter
I know this question is not new, in fact I learned the basics of this circuit from sites including this one. However I am planning on making a PCB with it and do not have the luxury of multiple ...
user56054
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1
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33883 H-Bridge Driver IC Intermittent Switching
I am using a NXP (freescale) 33883 H-Bridge gate driver IC to drive a simple H4 bridge circuit which is connected identically to that in the application schematic in the datasheet:
I am switching at ...
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1
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172
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Question on Mosfet Driver
I have got a PWM board from china that outputs at 5V but at 100 kHz, the voltage drops to about 2.82V. Hence I have implemented a mosfet driver to pull the amplitude ideally to be 10V to drive a ...
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2
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787
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What are the parameters to consider while selecting MOSFET or IGBT for Inverter and SMPS Design [closed]
I'm working on a project to design Buck Converter with following Criteria
Vin: 4.5-60V
Vout:8-15V
Iout:6-12Amps
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462
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Using mosfet with barrel jack shunt pin to shut off regulator
In the below schematic, I am trying to use the shunt pin (normally connected to ground when a barrel plug is not inserted), to allow the switching regulator, U3 to ...
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Mosfet is getting hot in switching circuit
I've built a NiMh battery charger (6-cell battery, 7.2v, 3000Mah) using DS2715.
Input is 12v.
Here is the schematic:
For Q1 I used IRF9540N
For Q3 I used IRLB8721PbF
L1 is a 47uF ferrite choke
R7 (...
- 341
1
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1
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9k
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Current limiting using P-CH MOSFET
I am currently building variable voltage/variable current (lab) power supply out of an ATX switching power supply. I have done voltage regulation tweak of the TL494 so now it gave me variable voltage ...
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1
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653
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Using MOSFETs To Automatically Switch Between 2 Power Supplies [duplicate]
For my circuit the primary Power Supply is a 6V Solar Panel (Note that for the most part the Solar Panel is usually well below 6V but it varies anywhere between 6V to 0V depending on light conditions.)...
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How to cut of the DC supply from a high power motor control?
For my project I built a BLDC motor controller.
Now I have to cut of the controller from the battery.
A relay is not easy because common my application needs >200Amps
The highside switches I ...
- 23
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2
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174
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12V in, 1V @ 12 Amp Out, Buck, Why 100 Amp MOSFETS and 60A Inductor?
I was showing someone the TI Workbench and it came up with this schematic.
94% Efficiency, switching Freq. 100khz
With voltage of 12v and 1v, max Amps of 12, why would it select 25v and 30v 100 Amp ...
- 7,517
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2
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Switch between 2 power sources
I have one power source (bicycle dynamo) A.C 5-6V which will be rectified to D.C, and the other source D.C from a solar panel 12V. It will be 2 input source and one output.
what type of power switch ...
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2
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Switch between two power supplies
[![enter image description here][1]][1]I am trying to build a simple circuit to power a load with two different power supplies (5 V and 0.7 V).
When one is active the other one is not and it's ...
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2
answers
397
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pulse width modulation versus amplification
If I want to make a sine-wave inverter where the output AC voltage is lower than the input DC input voltage, how can I see that using pulse-width modulation will be more efficient that just using a ...
1
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2
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2k
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MC34063 help - step-up with an external switch
I'm attempting to design a ~200V, relatively low-current (10mA expected, I'm allowing a bit more though) power supply for some Nixie tubes, and I've decided on using an MC34063 step-up converter. It ...
- 445
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1
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Will adding an external MOSFET on the switch pin of a boost converter IC increase the output capacity in terms of current?
So, I need a step-up DC-DC converter. I was going to use the LM2577 but I realized that the output capacity wasn't enough for my application. I was wondering if by passing the current through an ...
- 139
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742
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Inductance overheating
I have a circuit designed to run a electro piezotransformer at resonance frequency of around 80kHz. As a controller was used microcontroller Attiny 25, which by measuring feedback current generates ...
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Transistor PWM Generator (No ICs) for practical application
I want to produce a good quality PWM signal with transistors(BJTs, FETS, etc..). I do not want to use an IC at all(learning to use transistors properly). I'm currently using a BJT Astable Mutivibrator
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3
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What causes this knee in my MOSFET drain voltage drop?
FINAL UPDATE: Understand a previously mysterious power MOSFET switching waveform wiggle! @Mario uncovered the root cause here below, distinctive to so-called VDMOS devices, typical of many power ...
- 7,152
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3
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946
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N-Mosfet switch circuit strange behavior laboratory power supply
I'm dealing with an N-Mosfet switch circuit to control, through PWM, the temperature of a heater resistor. The mosfet is a IRFS7430-7PPBF.
The load is driven at 12V and has a power rating of 80W.
...
- 1,045
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1
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869
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Limit the current of a fixed voltage via MOSFET+PWM
I have a SMPS which I would like to current limit. The current limiter should have a negligible voltage drop when not limiting (say, <0.5%). I thought of inserting a MOSFET and a hall-effect ...
- 1,374
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1
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Push-pull switch mode power supply using an attiny84
simulate this circuit – Schematic created using CircuitLab
I'm trying to build a "push-pull" switch mode power supply. I'm not entirely sure if that is the right term, but it consists of ...
- 1,259
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1
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Why won't this PC power supply run my BLDC?
I would like to power my Arduino and BLDC to be powered with an old computer power supply. My Arduino needs 5V and my 3 phase BLDC needs 12V.
simulate this circuit – Schematic created using ...
- 803
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1
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812
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How much power IRFP460 can proccess?
I decided to use IRFP460 in a two-switch forward converter. This Mosfet can dissipate 280 watts. Can I get 1000 Watt from my converter?
As a general rule how much power a Mosfet can transfer with ...
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2
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High side Driver Issues
I am currently developing a small low power (high switching) Buck converter and have run into a strange issue that I have never seen before and was looking for some insight into the issue. I am also ...
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invert mosfet gate
Is there any way to invert the gate voltage of a mosfet. Weird question, but english is not my native language. I mean: Can I turn OFF a mosfet by applying a voltage at the gate?
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MC34063 Current Mode
I'm trying to build a LED driver using an MC34063 dc-dc converter in step up mode. Since LEDs need current mode operation to run stably, I elected to use a 51mOhm current sense resistor combined with ...
- 567
1
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2
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875
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Design/Build SMPS- PMOS or NMOS
I'm trying to design and build a simple ac/dc smps that outputs 5v dc and capable of 2 amps. I currently have it mostly designed using a nmos but the problem I'm running into now is how to get a pwm ...
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1
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668
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What is the circuit for the PMOS driver found in synchronous buck regulator ICs?
Some synchronous buck regulator ICs sport a NMOS lowside switch and a PMOS high side switch. I understand why these use a PMOS/NMOS pair instead of a NMOS/NMOS pair, but I can't seem to make sense of ...
- 1,388
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Using a SMPS converter IC as a controller
I'm building an LED driver using the LM3410. The internal switch supports a current of about 2A which should be adequate for my needs, but if I need more, can I use an external MOSFET to act as a ...
- 567
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2
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801
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5V 5A rail controlled by 3.3v microcontroller - dual switching or power mosfet?
I think this is a common situation so hopefully an answer helps more than just me. I have a 3.3v low power MCU which will be controlling a 5v 5A run of LEDs. When the LEDs are off the system will go ...
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2
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How to bypass DC-DC converter with N-channel high side MOSFET
I have a DC-DC SMPS converter which is used as a pre-regulator in the power supply with linear post-regulator. A specific requirement is to provide mode of operation when pre-regulator is bypassed. ...
- 179
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1
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Boost SMPS getting very hot. Why?
I tried to experiment with boost SMPS with multiple supply rails and I almost burned myself when touching parts when running.
Here is the circuit and the part getting hot:
simulate this circuit &...
- 2,883
1
vote
1
answer
2k
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Flyback converter current flow?
If you look at the flyback converter circuit above, the current only flows in one of the coils at any instant of time. What stops the magnetic field generated by the coil in series with the MOSFET to ...
- 221
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1
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Do AC inverter H bridges ever get driven this way?
There's a google competition going on at the moment called the little box challenge. It's to design a very efficient AC inverter. Basically the inverter is fed a DC voltage of a few hundred volts and ...
- 473k
2
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1
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993
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How does the PWM from MCU get translated into a output voltage as in Power Electronics [closed]
Background: I am preparing for a full-time employment starting in May. I am coming from a computer engineering background so I only have some working knowledge regarding EE. The job duty is Firmware ...
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2
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How does power dissipation for surface mount components work?
I know that with usual through hole components we can attach heatsinks etc. But how does it work with surface mount components? Is having a copper plate around the component the way to go? How do we ...
- 1,831
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2
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3k
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Driving MOSFET of 3.3 V gate voltage with 1.8V PWM pulse [closed]
My micro-controller is giving a PWM output of 1.8V. I need to drive a MOSFET with typical gate voltage of 3.3V. I am planning to use two cascaded switches (NOT gate configuration).
I have checked ...
- 1,635
1
vote
2
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913
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What transistor or combination of transistors should I use to make a fully controllable AC switch?
Suppose I want to switch AC. I want to control (allow, prevent, or interrupt) current flow in either direction. SCRs won't do because I want to interrupt current, and I don't recall seeing many IGBTs ...
- 17.7k
2
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3
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4k
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Switching 60V with 3.3V microcontroller at 50kHz - 1MHz
I'm playing around with some switching mode power supply things. For this reason, I'd like to switch the input voltage with a microcontroller, from the PWM output or other output pins.
The specifics:
...
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