Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [pmos]

A p-channel metal-oxide semiconductor (pMOS) transistor which has has p-type carriers used in the channel. The channel is established by a negative voltage on the gate which inverts the substrate (NWell) under the gate which turns the device on. The term may also be used to describe logic circuits built around pMOS transistors.

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Why old PMOS/NMOS logic needed multiple voltages?

Why does old PMOS/NMOS logic needed multiple voltages like +5, -5, and +12 volts? For example, old Intel 8080 processors, old DRAMs, e.t.c... I'm interested in the causes on the physical/layout level. What was the purpose of these additional…
BarsMonster
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Is there a popular small signal PFET equivalent to NFETs 2N7000 or BS170?

Some days ago I was considering using a small signal P-Channel MOSFET in a design of mine, but could not find a suitable part. The specs I was looking for were something like the following: \$I_D = -500mA\$ (continuous drain current) \$V_{GS} =…
Ricardo
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P-Channel MOSFET Inrush Current Limiting

I have been searching EESE and Google for several weeks now for a solution to this problem, and while I found some proposals that seemed promising, the real-world implementation fell short of expectations. I have a voltage regulator on a board with…
DerStrom8
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P-Channel MOSFET high side switch

I am trying to reduce the power dissipation of a P-Channel MOSFET high side switch. So my question is: is there any way in which this circuit can be modified so that the P-Channel MOSFET will always be "fully-on" (triode / ohmic mode) no matter…
Buzai Andras
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Where are the depletion PMOS transistors?

In school, I was taught about PMOS and NMOS transistors, and about enhancement- and depletion-mode transistors. Here's the short version of what I understand: Enhancement means that the channel is normally-closed. Depletion means the channel is…
Stephen Collings
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Why do we use a CMOS for inverting a circuit when the PMOS already achieves that?

The output in a PMOS is as follows: I/P O/P 0 1 1 0 Why can't I just use this instead of using a CMOS for inverting logic? (Please explain in simple terms as I am a beginner in this topic and subject)
Harshit Pandey
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P-channel MOSFET gating circuit that passes voltages above 17 V

I'm designing a desktop PC motherboard with AMD Ryzen™ 9 7940HS. We have an extension board similar to this one that performs negotiations with USB-PD charger and provides 20 V constant voltage to the platform. This board is designed by outsource…
Firas Abd El Gani
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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 schematic, let's say I have a P-MOSFET (type SiA441DJ),…
Oliver Richter
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Buck converter without oscillator?

I apologise for the attached picture, I just made sure everything is readable so you can assist. So I'm wondering if this is a logical idea, if 12 volts is supplied, to the circuit, as the capacitor reaches the zener 5.1v + 0.65v of the transistor…
BELSmith
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Pull up resistor on P-MOSFET gate. Not working

I am building a battery-powered datalogger that will communicate using cellular signal, based on the ATSAMD21 microcontroller and the SIM5320 cellular modem. To save power, an outside timer periodically switches the microcontroller on/off (not…
Michael Santiago
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Micro SD card power circuit failure

Description I am designing a system in which there's a circuit that controls the power applied to a micro SD card (enable/disable). The circuit is the following: The power control circuit is done by a P-MOSFET that is deactivated by…
johsey
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Reverse polarity protection - PMOS vs Schottkey diode

I have a circuit running from 2 AA cells in series, meaning I get 3.0V when fresh (or 2.4V if NIMH cells) and it goes down to 2.0V, that's when my circuit cannot function anymore (no DC/DC onboard). It's a very low current circuit (<30mA 99% of the…
mindbomb
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What problem is solved by using a PMOS for reverse polarity protection instead of an NMOS?

Many resources suggest the use of a PMOS for reverse polarity protection instead of a diode, as it decreases losses. However, the characterstics of an NMOS are better than a PMOS, so why is using it for reverse polarity not often mentioned? Here's…
Anas Malas
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Why do we need transmission gate for XOR (transistor level design)?

The following image shows a 6-transistor XOR circuit. But I don't know why the last 2 gates are needed at all, the circuit can be simplified to: Is there anything that prevents us from using the last circuit? I tested all 4 scenarios of (A,B) =…
Balawi28
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N-MOSFET driver for P-MOSFET high side switch

I need to create a high side switch to drive a 2.5W resistive load, which must be referenced to ground. I'm planning to use a P-MOSFET as load switch. The problem is there I have an inconstant voltage source from a battery (from 4.2V to 2.5V) and my…
Francesco
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