New answers tagged mosfet
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How does this PNP transistor and P-channel MOSFET circuit work?
First consider the circuit without Q4. What remains is Q2, R1 and R2:
simulate this circuit – Schematic created using CircuitLab
With Q2 being a P-channel device, gate potential (\$V_C\$ at ...
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How does this PNP transistor and P-channel MOSFET circuit work?
Arranging the circuit so as to be more understandable and easier to analyze, although constants are missing, from an analysis by inspection I obtain:
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How does this PNP transistor and P-channel MOSFET circuit work?
AS already pointed out, it is a "current" source ... unless R3 < 200 Ohm.
The current value is ~ 10/160 = 0.0625 A.
- 11.9k
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Eliminating a weird pulse when switching a valve actuator using a low-side MOSFET
The delayed return to the 24 V level may be due to an RC snubber circuit already within the assembly. Note that in the valve's datasheet there is this entry: "Additional functions - Spark ...
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2
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How does this PNP transistor and P-channel MOSFET circuit work?
It's a current source. The wire from the drain to GND is virtually a short circuit, but it's current is limited to 0,6V/R1. I bet it would often be more useful to have some load instead of a wire. But ...
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Need 120 A current limiter for 200 A source
There are current limiting DC/DC chargers already present on the market, commercialized, for this precise user-case; charging lithium from an alternator source without igniting everything.
The only ...
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-2
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How does this PNP transistor and P-channel MOSFET circuit work?
In principle, it is nothing else than a classical amplifier stage in common-emitter configuration - however, with a pretty uncommon feedback circuitry, controlled by the collector voltage.
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Confused about the safe operating area of a MOSFET graph
Please note the test conditions in the upper right corner.
As long as you have a cooling mechanism that manages to keep the case temperature at 25 °C, the die will not go above 175 °C, and it will ...
- 18.8k
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MOSFET gate driver current requirement for 2000 volt MOSFET
As per the data sheet of the MOSFET, the test condition is given at gate resistor 2 ohm and Vgs change as (18-(-2))=20V. So, as per this, the peak gate current requirement is 10 Amp.
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The condition of linear operation of the transistor Dipole in small signal mode
For a BJT, the voltage scale is the thermal voltage, about 26 mV at room temperature. The base voltage change must be substantially smaller than that to approach linearity.
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Design of 13.56MHz RF generator circuit for driving capacitively coupled plasma
For plasma ignition the two type of systems had been traditionally used. First was the vacuum tube circuits exploiting the parallel resonant tank. Thus tube having anode voltage 1000-1500 V but max 50 ...
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Design circuit for control line operated by GPIO output pin
The control line voltage in the schematics seems to be 1.8v, so why use a voltage divider that delivers 1.65v to the control line and XVS trigger pins? I can see that 1.65v is exactly half of the 3.3v ...
- 16k
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What kind of bridge would reverse DC motor with negative signal
If the voltage of sensor is above +0.6V the T1 and T3 conduct. Is lower than -0.6V the T2 and T4 conduct. You can remove these offsets placing a diode into T1 and T2 bases but the motor will run all ...
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Understanding the circuit 15 Ampere Solar Charge Controller without Microcontroller
That's a very basic charge circuit. Better ones use maximum power point tracking. The article itself gives a description of how it works. Essentially, all it's doing is monitoring the battery ...
- 18.9k
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Clock Driver - What's wrong with my H-bridge design?
Q1 dies because its gate-source voltage goes outside its limits. As you can see from the datasheet, its maximum allowed gate-source voltage is ±12V.
But once you enable it, the gate-source sees -24V (...
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Dual N/P-Channel MOSFET Dies with Smoke
When Q1 turns off, the drive is limited by the 47K resistor. The charge time is about R2 x total gate capacitance, or 47K x 3nf = 141us, and during this slow transition the n and p transistors burn as ...
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driving mosfet gate with an npn bjt
I use the 1st circuit for years now for 24V PWM dimming of LED's.
It works OK for 500Hz down to 1%, but when you go lower than 1% or increase the frequency you need the 3-transistor circuit.
Note that ...
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MCU signal isolated and Amplified (Optocoupler+BJT+Mosfet)
Let's start from the right.
The MOSFET datasheet mentions a gate charge of Qg=40nC ; i=dq/dt so if you drive the gate with 1mA it will switch in 40µs (more or less). Your switching frequency is only ...
- 71.9k
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Am I using these MOSFETs correctly?
One likely problem is that the \$V_{GS}\$ you're applying to those MOSFETs, which is 5 V, is much lower than what they're designed for. The datasheet for the FQP30N06 promises that if \$V_{GS} \le 2 \ ...
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Am I using these MOSFETs correctly?
FQP30N06 is not a logic level FET so you can never switch it fully on with the Arduinos 5 V. Furthermore, it's a N-channel and you connected it before the load not after leading to even less on-state ...
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TC4420 MOSFET Driver Output Latching Behavior
This device has extensive anti-latch-up circuitry, so will not latch-up.
Since the device input is high impedance, the output can be driven high or low depending on external factors associated with ...
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PMV20XNER MOSFET Overheating
Now after some comments I am quite sure, that your problem is contact bouncing.
While you touch the GPIO or even the gate of the MOSFET with a cable, you create very random contact bouncing. In ...
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Power Dissipation VS Switching Power
Answer to question 1: No. When you are treating a MOS transistor as a switch, it is either ON or OFF. The values stated in datasheet can be interpreted as follows:
The maximum current value (in your ...
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Current into DC/DC or LDO doubt
In comments you clarified the requirements:
from 0 to about 2.5/3V ... output signal must be 3.3V; from 3V to 24V ... the output must be 0V;
To meet this requirement, the safe way is to use a ...
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Current into DC/DC or LDO doubt
I think it can be simplified like this:
So there is no problem with current flowing from 24v to 3v3 except reverse leakage of the diode (nA).
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Simple phototransistor circuit to turn on P-channel MOSFET
An alternative solution is to put a Schmitt trigger in series between the photodiode and the gate. It will gives a perfectly contrasted signal instead of fluctuating and unpredictable voltages.
The ...
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Simple phototransistor circuit to turn on P-channel MOSFET
The circuit looks correct in principle. But you missed some details:
simulate this circuit – Schematic created using CircuitLab
Your thinking is: When there's no light the Vgs of the MOSFET is -...
- 30.2k
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Correct circuit design to light an LED
In the schematic you posted, Q1 is semi-backwards. Connect the source to GND, reverse the LED, and connect the LED anode to the 3.3 V source. Now the transistor will act as a saturated switch for ...
- 18k
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Correct circuit design to light an LED
EDIT: Your fixed circuit will work perfectly. The only thing is 100 ohms will make LED current quite high, you may not want to burn up the LED or be so bright - depends on your LED though. The LEDs I ...
- 137k
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Contactor circuit where MOSFET fails short
It's probably exceeding the "Safe Operation Area (SOA)" of the Mosfet. Have a look at the last graph on page 4 of the datasheet. Assuming the "Contactor En" port signal change is ...
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Audio switch using NMOS (low level signal)
You should switch NMOS and capacitor places, so it will always conduct in both directions, otherwise your gate-source will float and may distort.
Anyway 1K is way too much for 3A, that's 3kW of power. ...
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2
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High-Side Protection IC: what is the Vgs when IC is disabled?
Short answer: Zero.
The external gates are driven with current, not voltage. A charge-pump-driven current source (IGATE = 24uA to the top-left of the block diagram below) drives the output, and an ...
- 30.2k
6
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Which is the more important switching parameter in MOSFET datasheet? Turn on/off/delay times or Input/Output/Reverse capacitances?
Which one should be considered for comparing the MOSFET switching
performance between 2 MOSFET part numbers?
Neither, if you are interested in a real circuit that switches a real load powered from a ...
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4
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Which is the more important switching parameter in MOSFET datasheet? Turn on/off/delay times or Input/Output/Reverse capacitances?
Timing tells you how long it will take for it to switch. So this sets the speed you can operate them, setting maximum frequencies which you can use.
Capacitance tells you how much energy you need to ...
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Audio switch using NMOS (low level signal)
It is not the capacitor that is causing the increase in circuit gain, it is the 51 ohm resistor. (Reference designators - ?)
At audio frequencies, the cap is pretty much a dead short. It allows the ...
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Audio switch using NMOS (low level signal)
At the moment you flip the switch, your audio will instantaneously distort, since you are changing the operating point of the signal. Assuming you mean steady state distortion, there are a couple ...
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Audio switch using NMOS (low level signal)
This will work perfectly fine. As long as you don't make the MOSFET's body diode conduct with a reverse voltage greater than a few hundred mV, there won't be any difference between a simple NMOS ...
- 15.5k
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P-Channel Mosfet as a switch, always open when voltage to source and digital HIGH to gate
You have the NOR gate outputting 5V which, as Michal Podmanický said, is not high enough to turn off the transistor. Enhancement mode FETs need to have zero (or near-zero) voltage relative to the ...
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IR emitter circuit not working
There's many reasons they don't work or work poorly.
You are transmitting out only the baseband of the IR signal, which looks like NEC protocol. More specifically, it looks like Extended NEC protocol ...
- 137k
3
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MOSFET trouble with Arduino
It sounds like the GND pin you think you are connecting to is actually floating for some reason or another (bad jumper wire, bad solderless breadboard connection, bad solder joint, wrong pin selected, ...
- 383k
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Is keeping average current low a way to avoid damage to PSU and MOSFETs?
PWM is a process in which we reduce the total power by reducing the percentage of time power is supplied. In order for it to work well, there needs to be something to smooth the power out. Things like ...
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Is keeping average current low a way to avoid damage to PSU and MOSFETs?
You will put a lot of stress on the PSU since it will in reality be an overload 50-60% of the time. A SMPS is built to keep a steady voltage, and in this scenario the voltage will fluctuate along the ...
- 1,603
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12V piezo buzzer not working using ESP32
Thanks everyone, your feedback is very much appreciated!
I now tried a 1K reset transisor in parallel to the buzzer pins as proposed in the previous message and it works!
See option 1:
https://www....
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FDMS7658AS SyncFET replacement for a regular one, burned it
The AON6512 is a suitable replacement for the FSMS7658AS. In particular...
Its on resistance is lower at Vgs=10V and equal at Vgs=4.5V. That's an improvement and will lead to lower conduction losses.
...
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Capacitance of MOS capacitor vs orientation
Found the answer in Circuit Design, Layout, and Simulation by Jacob Baker (section MOSFET Capacitance Overview/Review).
The small-signal capacitance is comparable in inversion (\$|V_{GS}| > V_{TH}\$...
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Why does the voltage at the source side change even though it has no connection to the drain on this NMOS?
The simulator treats floating nodes as a connection to the ground through very high resistance – I don't know the actual value but let's say 500 GΩ.
The behaviour also depends on the MOSFET model you ...
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Why does the voltage at the source side change even though it has no connection to the drain on this NMOS?
In your simulation you don't have a load to ground on the source side. Without a load, leakage through the MOSFET channel will cause the source to float up to the voltage of the drain.
However, ...
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The input to the gate of an N-channel MOSFET is a pulsed signal but I am getting a ramp signal
You've got two separate problems.
The first is the low output current. You simply cannot get 10A through a 10 ohm resistor with a power supply of only 50V. Ohm's law (E=IR, rewritten to I=E/R) says ...
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The input to the gate of an N-channel MOSFET is a pulsed signal but I am getting a ramp signal
IRF530 has RdsON of 160 mOhms which corresponds to a dissipation of 16W at 10A, which is unnecessary. Here's an example thru-hole MOSFET with 10mOhm RdsON, although I believe SMD would be better ...
- 71.9k
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12V piezo buzzer not working using ESP32
I have something like it.
I am using a piezo buzzer too, but mine is 5V and I am using a BC846 NPN to drive it with my ESP32S3 pin.
Note that I am using a diode in parallel with the buzzer.
It works ...
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