Questions tagged [p-channel]

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What is the use of a P-channel FET on a power line?

I was going through a schematic of one controller. I found this circuit for the VIN pin: What is the DMG2305UX (Q1) P-channel MOSFET used for? I have read that MOSFETs are used for reverse polarity ...
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  • 429
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54 views

Help with power supply ORing circuit

I'm checking a system that has an ORing circuit to allow a battery backup for when the power supply is cut and it seems like a MOSFET (Q3) is backwards of how it should be. Vin=3.9 V (at LM66100), ...
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1 vote
3 answers
76 views

P channel to get input signal state

I want to detect when a ground input is connected to my circuit. My specs are, that when there is no ground signal then 0V needs to go to my microcontroller. When I have ground connected to my circuit ...
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High side reverse voltage and overvoltage protection circuit

Can someone provide an explanation why I still have a 50Vp negative waveform after the rectifier (waveform on Vch2) and after the overvoltage (output voltage) we have the same positive cycle. It's ...
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PFET switch design not behaving as expected

I'm trying to use a P-Channel MOSFET as a shutdown switch for a logic circuit. I have what I want working in isolation, it looks like this: These are the voltage curves: As you can see, the initial ...
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2 votes
2 answers
169 views

What is the purpose of the capacitor (C97) in between the gate and drain of the p-channel MOSFET in this power control circuit?

I can't figure out what purpose the capacitor serves.
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3 votes
3 answers
478 views

Would this inrush current circuit work in practice?

I am building a USB hub circuit, which, because of the 120uF capacitance requirements on upstream USB ports, means that I need to charge those large capacitors in my circuit. However, my hub will be ...
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0 answers
61 views

P-MOSFET driver

I need to drive a P-channel MOSFET from an output of a 74HC595 shift register which is controlled by an ESP32. The MOSFET load will be a high power LED. Once the register is latched the outputs will ...
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1 vote
1 answer
91 views

MOSFET PWM issue

I want to dim an LED and have connected a P-channel MOSFET to switch the high side. I added a N-channel MOSFET as a driver. The schematic is attached below. I'm applying a PWM sine signal from an ...
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0 votes
1 answer
159 views

P-Channel MOSFET power selector question

I've seen this circuit used in several ESP32 designs (e.g. the Sparkfun ESP32 Thing) and in an answer on this site that allows a device to be powered by either 5V from a USB connection or a battery. <...
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7 votes
6 answers
2k views

Can you drive a P-MOSFET as a high side switch directly from a microcontroller?

I have an engineering background, but close-to-zero practical experience with discrete electronic circuit design. simulate this circuit – Schematic created using CircuitLab Regarding the above ...
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0 votes
1 answer
51 views

Power consumption for reverse polarity protection using p-channel MOSFET

I'm looking for a way to implement reverse polarity protection for a circuit that runs from a CR2032 battery (The operating voltage of the circuit is from 1.8 V to 3.2 V). I'm considering using the ...
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1 answer
113 views

How to use a MOSFET to switch up to its Vds rated specs (e.g. 100 or 150 V)?

So I'm still learning (old dusty ETE degree I finally got around to making use of lately), so be nice please. I get a ton of snark sometimes when I post a question on here. But then there's always one ...
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4 votes
2 answers
1k views

Reverse Polarity Voltage Protection Using P-MOSFET

Could you please help me understand why in a reverse polarity circuit with P channel MOSFET Source of the MOSFET is connected to the LOAD and DRAIN to the power supply? I understand the concept of a ...
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-1 votes
1 answer
68 views

What is a through-hole equivalent to the irlml6401 P-channel MOSFET [closed]

Newbie here. My hobby project uses the irlml6401 P-channel MOSFET but I'm finding it impossible to solder the surface-mount package it comes in because I have trembly hands (gets worse as I try to be ...
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0 votes
2 answers
217 views

How to calculate base voltage and current for NPN transistor required to drive a P-channel MOSFET gate

I'd like to use a P-channel MOSFET as a on/off switch. I can't pull the gate down directly from my controller because the voltage of the load is 12v, thus I have to use another transistor, as far as I ...
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1 vote
1 answer
129 views

How to operate a P Channel Mosfet with an LM358 OP-AMP to by-pass a DC DC power supply with 5-24vdc in and 5v OUT

I am trying to create a PCB that can operate on 5, 12 or 24 V DC. The PCB will need a 5v rail for the digital signal to LED lights and a 3.3 V rail for the MCU. I would like to make a cost-effective ...
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0 votes
1 answer
83 views

Delay circuit after power on for ESP32 application

I'm using the ESP32 with a sensor connected to UART0 and I want to suppress the first stage bootloader log, since it can lead to delayed response of the sensor later on. Therefore I want to pull the ...
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1 vote
3 answers
138 views

Does the Zener diode in this schematic need a current limiting resistor?

This is a fairly generic P-Channel MOSFET driver. The supply voltage is 12 - 48 V. The Zener used is a BZX84-C12. Would this Zener diode need a current limiting resistor of, say, 1 kiloohm between <...
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0 votes
0 answers
156 views

Which circuit is better for P-Channel MOSFET ESD and over-voltage protection?

There was damage to some P-channel MOSFETs on the PCB due to ESD and dielectric strength tests during our manufacturing. I think the original circuit design is susceptible to high voltage stress. A ...
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0 votes
0 answers
93 views

Turn on led with p channel mosfet when voltage drops?

I have a project where, without a microcontroller, I am trying to trigger an led when voltage drops by an amount, and increase brightness of that LED steadily as the voltage continues dropping from ...
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1 vote
1 answer
289 views

RDS measurement on P-Channel MOSFET

I want to measure the Rds-ON of a P-Channel MOSFET and I have setup the test circuit as follows: I keep the source at constant +10V and vary the step the gate voltage up in the increments of 1V. Then ...
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3 votes
0 answers
68 views

High-side mosfet switch placement

this is a power circuit I'm trying to complete: the button at top turns the curcuit on, supplying VCC to mcu, and the MCU will output a high signal to a pin (marked in pink) which turns the N-MOSFET ...
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2 votes
1 answer
96 views

Problem Implementing high side P channel mosfet power source selector

I have build the above circuit on a breadboard and it is almost working but not quite. I've spent a number of hours on the problem to no avail. My background is not electrical but I've been building ...
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1 vote
2 answers
101 views

basic p-type mosfet circuit, breaks mosfet?

So I've made this basic circuit to drive Vout between ~0V and ~1.65V. The default state should be ~0V, hence I use a p-type mosfet: https://docs.rs-online.com/d95a/0900766b800ae907.pdf Now, for some ...
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2 votes
3 answers
249 views

How is current flowing through this P-Channel Mosfet?

I am probably being stupid and should probably go to bed but how is current flowing in this circuit below? From my understanding, a P-Channel Mosfet allows current to flow when its gate terminal is ...
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0 votes
1 answer
47 views

what driver chip do i need for a irf4905 p-channel mosfet [closed]

I'm trying to figure out what chips I need to run my irf4905. the mosfets will need to be running 5 amps at 24 volts using pwm to Varey the watts. if anyone has done anything with this mosfet an knows ...
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1 vote
1 answer
80 views

Does this Buck-converter work?

I am using the buck-converter circuit from Low side N-Mosfet buck converter as the base of my design. And I want to replace the diode with a P-channel MOSFET. I also want to drive both MOSFETs with an ...
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0 votes
3 answers
237 views

P-Channel MOSFET has a really high voltage drop

I just got a new P-Channel MOSFET FQP47P06. In the datasheet it says it has an RDSon of 26 milliohms, Vgs(th) of -4V, and a max current of 47A, but when I hooked it up in a simple test circuit like ...
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1 vote
0 answers
699 views

Zero Gate-Voltage Drain Current (IDss) vs Drain Source Voltage (Vds) relation for PMOS

The Drain to Source leakage current Idss at Zero Gate voltage (Vgs= 0) is normally 1uA(max). However the relationship (or Graph) with Vds (Drain-source voltage) is not mentioned in Datasheet. Que: ...
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0 votes
1 answer
80 views

Best way to turn off P-FET with 3.3V available (P-FET Load Switch Application)?

honestly I'm drawing a blank. I am trying to turn on and off a load with a P-CH MOSFET. I used generic resistor values just to be clear. Now, in this example the VGS will clearly never go to 0. It ...
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1 vote
2 answers
338 views

understanding p-channel MOSFET unexpected behavior

I'm fairly inexperienced and while I have an understanding of classic npn and pnp transistors, I'm shaky when it comes to MOSFETs. I'm looking for an element to act as a switch. This element would be ...
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2 votes
2 answers
79 views

Arduino resets randomly when using a DC motor

Following a question I posted here a few months ago Using P-Channel mosfet with arduino I'm using pchannel MOSFET for activating a CR02 valve like this one https://es.aliexpress.com/item/1938516987....
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  • 461
0 votes
1 answer
72 views

Short-Circuit Protection for 3-6 Volts AA batteries

I’m looking for a circuit that can protect 3-6 Volts AA Batteries when a short-circuit happens. When the short-circuit happens, a second circuit (LED blinking) must be triggered and the batteries must ...
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4 votes
2 answers
506 views

Solution for how to drive a P-Channel MOSFET when Gate/Source voltage is too low?

I have used this forum to lookup solutions and suggestions from time to time but this is my first ever post! There are many great P and N-Channel MOSFET Questions and Answers in here, but I cannot ...
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1 vote
1 answer
303 views

P-Channel MOSFET high side switch in an MPPT buck converter gets very hot with no load

I am a novice working on an MPPT solar charge controller. Q5 mosfet (SUP53P06) gets very hot even when I have no load attached. The circuit is just like below except I have no current sensors in it ...
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1 vote
2 answers
734 views

Using P-Channel mosfet with arduino

I want to drive a 12v inductive load with arduino (a motor) . This device has 3 wires a common GND and one wire to go in one direction an another one to go on the opposite direction, as it has a ...
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  • 461
0 votes
1 answer
84 views

Iellegible JFET name, seems to be HEPxxxxx

I have this poor scanned schematic on which there is a Motorola P-channel JFET, labeled as Q5, and I can't read the name. It seems to me that the 2nd note is written "Q5 is HEP*1036" where * ...
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