Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [protection]

Ancillary circuitry that protects the main circuitry in case of a fault. Examples of faults protected against are: overvoltage, ESD, overheating, and overloading (too high of a current draw). In some cases the protection circuitry is sacrificial, being destroyed or degraded in the act of protecting.

Recommended reading:
How to protect low-speed interfaces and power supply circuits by Littelfuse (2021)

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What measures should I take to protect the USB ports of my PC during development of a USB device?

I'm going to start developing a USB 1.1 device using a PIC microcontroller. I'm going to keep one of the USB ports of my PC connected to a bread board during this process. I don't want to destroy my PC's USB port by a short circuit or connecting…
hkBattousai
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Understanding an 'ideal' diode made from a p-channel MOSFET and PNP transistors

The Raspberry Pi B+ models have a protection circuit between the USB connector and the 5V net on the board. They recommend putting a similar protection circuity on a Pi HAT before 'backpowering' the pi through its GPIO header along with a polyfuse.…
Mark Walker
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Correct use of Flyback or Snubber diode across Motor or Transistor?

From seeing a few schematics where the flyback or snubber diode has been placed across the transistor C-E terminals (Right Configuration), instead of what I typically seen as the the flyback being placed across the coil terminals (Left…
Passerby
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Reverse polarity protection

I read somewhere that this can be used for the reverse polarity protection in the circuit. But I am quite confused with its operation. Can somebody help me with this. simulate this circuit – Schematic created using CircuitLab
IamDp
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How diodes protect H-bridge DC motor driver?

I don't really understand how these diodes in this circuit and similar circuits (like driving a relay circuit) protects the controller circuit from the energy stored by the inductance of the coil. I really appreciate if someone could graphically…
Mehrdad Kamelzadeh
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Scam? Does having this capacitor wired as shown provide any surge protection?

Bought this on Amazon as a dryer 240V SPD. I was trying to find out if this device is an outright scam. I found a similar post on here from several years ago but that did not answer my question. Apparently this device was originally sold as a "power…
Jason P
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OR-ing power supplies (diode or mosfet)

I have got two power supply options on my board: USB 5.0V DC Power Jack of 5.0V My intention is to design a or-ing power supply option, as either of them will be used at a time. Possible solutions are shown below: Using oring diodes or using two…
AKR
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Lithium Battery Protection Circuit - Why are there two MOSFETs in series, reversed?

I was studying a battery protection chip and reference circuit (below) commonly used in cell phone Li-ion batteries, and am confused by the two MOSFETs in series on the negative terminal EB-. According to this question, I now understand that MOSFETs…
Ryan Griggs
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What is "foldback short circuit protection" in a power supply?

I am looking at buying a 24V power supply. Two of the options are these: PSP24-060S 24 VDC 2.5A (60W) power supply PSB24-060-P 24 VDC 2.5A (60W) power supply The first offers "foldback short circuit protection" and "overvoltage protection," but it…
Steven
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Regulated Joule Thief: why it works?

Please explain to me why this circuit can give me a regulated 5 V? I understand the Joule Thief part, but why the regulator part work? simulate this circuit – Schematic created using CircuitLab Especially, why the Zener diode D2 is crucial at…
Maxthon Chan
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Does an over voltage, over current and reverse polarity protection IC exist?

I'm designing a circuit that has the following protection requirements: Reverse polarity Over voltage (60v max) Over current (approx 1A) There's quite a large input voltage range, 10v to 60v. 48v is nominal, drawing about 150mA. At 10vin, it draws…
raaymaan
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Circuit to protect against undervoltage?

What is the simplest way to regulate the min DC voltage in a circuit? Is it possible to do with zener diodes? Desired performance: Input > 3.3 VDC Output = Input Input = 3.3 VDC Output = Input Input < 3.3 VDC Output = 0.
PICyourBrain
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How does a diode clamping circuit protect against overvoltage and ESD?

I always see this circuit when talking about overvoltage or ESD protection (does this circuit accomplish both, or just one?): However, I don't understand how it works. Say I put in 20V at Vpin. So Vpin is at a higher potential than Vdd, so current…
tgun926
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Optocoupler input protection

I have to provide some isolated inputs that accept 12-24V. There should be some protection against reverse polarization, transient over-voltage and permanent over voltage (up to 40V) to some degree. So far, I came up with the following…
Rev
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What happens after a zener diode breaks down?

I've strapped a 6V zener diode across the 5V/GND rails of my circuit, and I want to know what will happen if my supply were to somehow fail pass 12V straight to the rest of my board. The zener will definitely fry, but what happens afterwards? Can I…
wjin
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