Questions tagged [protection]

Ancillary circuitry added to a design that provides protection of the main circuitry to enable the main circuits continuing functioning. In some cases the protection circuitry is sacrificial, being destroyed or degraded in the act of protecting. But not all protection circuits may do this. Examples of faults protected against are: Overvoltage, ESD, overheating, Overloading (too high of a current draw) amongst others.

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What is the purpose of this dual-facing diode?

I'm trimming off some parts from an eval board schematic, and I'm not sure what the purpose of this dual-facing diode / rectifier is. The voltage divider from R33 and R48 is scales by a factor of 10 ...
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CAN bus fault protection

Question: Is there a way to implement with discrete components the 70V CAN bus fault protection found in some transceivers, such as TCAN1051H-Q1 ? Background: We are using the CAN transceiver ...
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Code protection (firmware security) in PI PICO RP2040?

What are the available code protection (firmware security) options for off chip flash in PI PICO RP2040 for industrial IP critical designs?
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Simple short, overvoltage and reverse polarity protection

I am looking for a simple way to protect the 3.3 V power supply to which the MCU and other peripherals are connected. The protection is supposed to be against short circuit, overvoltage and reverse ...
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Protect bus and remaning bus-attached devices for bus-attached device failure (CANBus)

What are options to protect CANBus from failure of device connected to bus? For example if CAN Transceiver pulls bus high or low. Or some other sort of electronics failure. Thx
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Opamp output clamp

During power-up, U2A's voltage will be undefined. I would therefore like to clamp it with a relay. Additionally, U2A is buffering a voltage from a 20-bit DAC -- therefore I need to care about thermal ...
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OVP with crowbar + TVS?

I'm looking to design an over voltage protection (for > 13-14V situations) on the input of a power supply (the PS is taking input from a 12V vehicle). I was considering only using a crowbar circuit ...
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How to protect home from the main connection line short circuit?

I am living in a village and we often face issues with main connection input neutral getting shorted and having good amount of current/voltage. The transformer often gets issues, disrupting supply and ...
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1 answer
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Large series resistor to protect from shock

I built a high voltage generator and want to protect myself against shocks. Would putting a large series resistor on the powering circuit be sufficient to protect me in those cases: I build a large ...
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Deep discharge protection of LiFePo4 cell with a single MOSFET with the right threshold voltage

Is it possible to build a deep-discharge protection circuit for lithium based rechargeable batteries by putting a simple enhancement mode MOSFET with a threshold voltage that is equal to the discharge ...
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2 answers
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Negative Voltage Reverse Protection

It's easy enough to use a P-channel MOSFET for doing positive high-side reverse voltage protection. However, is it possible to do something similar for reverse protection for a negative voltage? I've ...
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1 answer
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difference between N and X relays?

I have seen in some SLDs for overcurrent relays there is a X unit and N unit. I understand that the N unit grounding relay is for zero sequence and the G unit is sensing the current flows through the ...
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3 answers
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DC over current protection idea needed for step down converter input

I ride an electric motorcycle which is powered by a 26s 96V Li-ion battery. It has regen braking that charge the battery with 50A current. All the lights are powered by a 60v-120v to 12V 15A DC step ...
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Component selection for IGBT desaturation detection

I am designing a circuit for driving a DC motor, and want to include overload protection, for that I found that detecting desaturation is a good option to detect high current flow. I sketched the ...
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2 votes
2 answers
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Protecting MCU digital input with 300m wires

I need to protect the inputs and a 3.3V MCU (ESP32) from damage (eg lightning) and noise with a switch connected at the end of a cable that can be hundreds of meters long. Based on the schematic (Fig ...
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Can I set a pin high when it is connected to the SDA line?

I have an STM32 development board. I want use DCMI (camera interface) with this board. Unfortunately there is an AT24C02 E2PROM mounted on board with its SDA pin connected to the same pin used in the ...
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Folded Overload Protection in Linear regulator

Can someone please explain how Q1 is able to protect from overload this linear circuit? Please see below for a simpler schematic of the above:
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Undervoltage protection circuit design review

I want to design an undervoltage protection circuit. The nominal supply voltage is \$48 V\$ and the maximum load current is about \$ 0.5A\$. If the supply drops to about \$39 V\$ or below, a P-FET ...
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1 answer
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Difference between a relay and a fault passage indicator (FPI)?

What is the difference between a fault passage indicator (FPI) and a relay (for example relay 50, 51, 67N) ? Are they the same thing?
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4 answers
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What component is like a jumper, but doesn’t actually conduct?

I suppose you all know jumpers, those little things you put on top of 2 male, 2.54 mm pitch, pins. They serve to connect the 2 pins together (often used to "configure" a prototyping board), ...
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22 votes
3 answers
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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. ...
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Fault Protected RS485 circuit

I am designing a product for use in the industry and it needs to include a fault protected RS485 interface. In the industry the most normal voltage for the power supplies in the machinery is 24V, but ...
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1 vote
1 answer
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333mV Current transducer - how to read it and protect the Atmega328p input

i have this CT current transducer: it outputs 333mV at 5A full scale. I'm planning to use it in my house/office in order to detect if a load is switched on or off, but i'm worried about how i can ...
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Protection of short from 48 V to RS 485 data line

In a cable I carry a 48 Vdc supply line and a RS 485 differential signal pair from a SN75176A transceiver. The 48 Vdc line is protected by a 5 A fuse, and the SN75176A transceiver inputs and outputs ...
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3 votes
0 answers
90 views

What is an "integrated self-opening load switch" actually called?

Here is a throw-away circuit to illustrate the behaviour I'm looking for: simulate this circuit – Schematic created using CircuitLab Basically a load switch, but during an over-voltage event ...
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8 votes
9 answers
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Do I misunderstand fuses?

A statement that I often read here goes: "Fuses protect the wire, not the load." However, in basically all cases I use fuses, I think they are there to protect the load - I.e. the device on ...
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3 votes
2 answers
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What kind of weird current protection "circuit" is this?

After seeing this schematic in this answer (from @VictorTito ... and others) in this post ... I was curious to try it ... Added one resistor and I simulated this (?) (DC Analysis) ... Meanwhile, by @...
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High-power LED Shunt Protection using Zener diodes with constant-current LED Driver

I'm about to build a custom high-power lamp. The lamp will operate a total of 60 high-power LEDs (operating point: 2800mA @3.1V per led) connected in series. The original plan was to have the LEDs ...
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3 votes
4 answers
417 views

60V ADC Input Protection with Unpowered Micro

I am having some trouble solving an input protection issue for a design that has to measure the voltage of an input between ~10V two 60V DC via a microcontroller ADC. The issue is the micro may be ...
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2 answers
63 views

Isolated Switch

I have three question on designing Isolated switch (Protected Microcontroller and from accidentally inserting power) Does it matter which side is the switch - on 15V(Isolated side) (image 1) side or ...
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2 votes
2 answers
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What kind of protection does a circuit need to have for reading the output of a CT?

A CT (current transformer) is installed to measure the line current for digital measurement and protection devices. In many cases, the CT is installed in open weather or on poles, making it vulnerable ...
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1 vote
1 answer
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Does USB have some kind of current cutter that cuts the current for safety? [closed]

I accidentally got 24V into the GND on my Arduino and then the USB shut off - but not all of them. When I restarted my computer, then all USB shut off and they are not giving out any current. Notice ...
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13 votes
3 answers
2k views

Why is there a Schottky diode connected to the low-side switch

I am trying to understand the reason for having a Schottky diode for protection in a buck switch by reading here. To summarize, I can understand why two the switches should not be turned on at the ...
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How to protect this circuit from shorting out / reverse polarity?

I'm building a device that uses multiple TRS jacks for power and communication. (I know that audio jack is not the best choice for power but it's important for overall design and I really want to make ...
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1 answer
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How to arrange input protection components?

I want to protect the input of my 5V micro-controller from two types of disasters, I am detecting a low on the input (0V): The input is from a switch. When the switch is on it provides a ground. Over-...
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0 votes
0 answers
49 views

Simple undervoltage lockout

I have a generator that outputs upto 20v dc, to power a 12v led light I tried a buck+boost converter (xl6009 based), light requires 1Amp on 12v. Problem is when engine is not accelerated, generator ...
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-1 votes
1 answer
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Using P-Channel Mosfet as reverse polarity protection and load switch

I was wondering if a reverse polarity protection P-channel Mosfet could be used in addition with a small switch on the same circuit. As an example, the image has the original circuit (A) and the other ...
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-1 votes
1 answer
59 views

Grounded Reference Power Supply Output Problem

I have several cabinets. Each cabinet have 24V power supply that has option to select ground reference output or floating reference output. Please look at the picture, at the bottom of power supply, ...
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0 votes
1 answer
49 views

Typical power limit of zener in integrated IC input protections

I am using NCP1031 as a first stage voltage regulator IC in a PCB. Here is the block diagram of the regulator: And here is the link to its datasheet for easy access: NCP1031 datasheet There were a ...
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Li Ion cell charging and thermistors

I am designing a circuit to charge a small Li Ion flat cell with a capacity of around 300mAh. I want to charge it at around 75mA to 150mA max in the CC part of the cycle. It will always be charged ...
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0 votes
1 answer
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Is it possible to use 48V relay in 120V circuit by adding current limiting resistor and capacitor. Will this also speed up the response of the relay?

simulate this circuit – Schematic created using CircuitLab title kinda says it all, Was talking to another engineer and didn't quite follow how they said they could get faster trip coil response ...
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Transformer secondary conductor protection: how do NEC 240.21(C) and NEC 240.4(B) make sense together?

NEC 240.21 says all ungrounded circuit conductors require overcurrent protection, with a list of exceptions: One of those exceptions is 240.21(C): 240.4(B) says that if you're under 800 amps, you ...
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0 votes
1 answer
48 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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2 answers
228 views

AC overvoltage protection using Zener diodes (and some other things)

I am considering building an AC protection circuit using the following schematics. I am a physicist and have little practical experience with implementation of electric circuits. Looking forward to ...
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How can I connect ( and if required isolate a single module ) multiple LI-ion battery modules(with different SOCs) in parallel sharing common load

1.Need to connect two or more Li ion battery modules(having different SOC levels) in parallel with the help of bidirectional dc-dc converters sharing a common load(say 48V). 2.Isolating individual ...
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0 votes
1 answer
65 views

How should fuses be used for MOSFET temperature protection?

I am using high voltage MOSFET in TO-220 package with a heatsink like this one: Under normal conditions, the temperature of heatsink does not exceed 90 degrees. My MOSFET can run up to 120 degress ...
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1 vote
1 answer
119 views

How long TVS diode lifespan?

Do TVS diode have a lifespan? Do TVS diode protect against how many lightning strike during own lifespan? Can ı calculate life expectancy? I don't found any document about this issue
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0 answers
33 views

Protection and filter on USB Power Lane device

Struggling finding good information, I would like to know which protections should be on a USB device ? The device is custom battery charger pcb (using MP2607 from MPS) which should be plugged on AC ...
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0 votes
2 answers
74 views

How can I provide time-controlled current protection?

I need a component name or solution. I have a fan motor that I run with AC. I am controlling with MCU and driver. Operation logic: 0.75 s on, 9.25 s off. My circuit works flawlessly with this logic. ...
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2 votes
2 answers
158 views

How to protect a cheap RF amplifier from spontaneously dying?

I've bought a few RF amplifiers based on the SPF5189z LNA chip. These have decent performance for their price but there is a common issue where they just kinda die from pretty much any reason. I've ...
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