Anything related to depletion-mode devices (e.g. depletion MOSFETs, JFETs), i.e those semiconductor devices (largely FETs) whose output current (e.g. \$I_D\$) may be non-zero when the controlling signal (e.g. \$V_{GS}\$) is zero.
Questions tagged [depletion-mode]
19 questions
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1 answer
Alternative to depletion mode P-channel MOSFET based voltage limiter?
I find this voltage limiter circuit very simple and useful:
simulate this circuit – Schematic created using CircuitLab
To my surprise, neither Mouser nor Digikey have P-Channel Depletion Mode MOSFETs available anymore.
My question: What is the…
HannesW
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Identifying / distinguishing between PIN photodiode and avalanche photodiode
Is there any way to determine whether an unidentified photodiode is a regular PIN photodiode or is an avalanche diode? The photodiode is part of a small scintillation detector unit.
Eric Slighton
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3
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In depletion MOSFETs, what is the drain current value when \$V_{GS}\$ is zero?
When \$V_{GS}\$ is very negative \$I_D=0\$, whereas it conducts a little current when \$V_{GS}\$ is a little negative.
What is the value of \$I_D\$ when \$V_{GS}=0\$?
ema
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Schematic for input protection with NMOS? Does this really work?
I was reading an old schematic and found this and sketched it up;
(see box in image "Some kind of protection")
The closest thing to this schematic that I've been able to find, that could have briefly explained how it was works used a depletion mode…
user103776
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Unicorn Mode PMOS For Hurricane Flooded Golf Cart Controllers
We have saltwater flooded golf carts after hurricane Ian. Their old 0-5k Ohm throttle pots are shot, and replacing them is very expensive. The new throttle systems can be fitted more cheaply, but their resistances start about 800 Ohms rather than…
Elkrat
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Are there any substitutions for depletion PMOS transistors?
I am currently building a low-voltage cut-off circuit. When the battery is under 10 V, the microcontroller should pull the battery power to ground which will blow the fuse with high current and cut all the power to the loads. (Assuming the micro can…
Terry
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MOSFET depletion region
I was reading the answer from placeholder and re-posting his excerpts from an answer.
I didn't understand the following points well:
the channel has p-dopants in it which when the voltage is applied get ionized by the E-field. This is what…
Singh
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LED Driver IC to charge batteries
I would like to use the ZXLD1350 LED driver IC to provide constant current to some NiMH batteries to charge them.
However the negative terminal of the LEDs go to an inductor instead of ground.
My aim is to swap the LEDs below for my battery, however…
JC123
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Normally closed mosfet circuit
I'm designing a battery charging circuit for a portable device. Conceptually it looks lik so:
simulate this circuit – Schematic created using CircuitLab
As a safety function, the circuit can be interrupted by the transistor, thus interrupting the…
Sergi MF
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1 answer
Universal voltage input using depletion mode N-FET - Advice
In an attempt to idiot proof a device I am designing that needs both 24V DC and 120V AC inputs for logic, I set out to create an input system that could handle either voltage going to a simple 3.3V micro controller. Below is the schematic of what I…
MadHatter
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Capacitor problem using an NMOS inverter with depletion load
When Vin is low the enhancement type NMOS is off. That means the drain current of both transistor is zero, isn't it?
If it is, then how will the parasitic capacitor charge? I'm not understanding! And if it charges, how much will the maximum…
Enthusiast
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Depletion-mode P-channel MOSFET availability?
I need a P-channel depletion-mode MOSFET for a circuit I'm building. However, there is no model available in LTspice that I have found, nor is there any available that I have found to buy online.
How can I simulate this kind of MOSFET in LTspice,…
Allenph
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How turn a transistor ON when the control signal is OFF
I am creating a light control circuit with a low-power tilt switch (>0.1A) to automatically turn lights on and off when the switch is tilted. When the switch is level, it is open, and I want the lights to be on. When the switch is tilted, it closes,…
Raddy
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Can I bias a depletion mode FET with a diode?
I'm trying to work out how to bias a dual gate MOSFET that I'm working with. Its behavior is halfway between depletion and enhancement modes. That is, its ideal VG range is about -1.5V up to about 0.5V. It looks like it needs VG-S to be biased to…
Toby Eggitt
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Advice for P-Channel Mosfet in Depletion Mode
i want to be able turn off a led with a mosfet and a pushbutton. In order to do this i want the led to be in off state when voltage is applied to the gate of the mosfet. After researching for a while i found out that i probably need a p-channel…
abdussamed17
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