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Questions tagged [over-voltage-protection]

Additional internal or add-on parts to a fixed voltage regulator to prevent the output voltage from exceeding a preset limit if internal voltage regulation fails. Some OVP designs include an SCR to short the output and blow a fuse, rather than risk damage to downstream hardware.

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30 views

pulled down io protection from overvoltage

I need to protect my IC's io form overvoltage(default is 5v). The pin has the capability to source 10 mA and sink 25mA I tought of using a tvs diode(between pin and gnd) and a resistor(330r from pin ...
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41 views

Over voltage protection without shorting the Output to GND during Over voltage

Here is the circuit diagram i am referring. Vin_12v_ext - Max 12V; Batt_V = max 5.4V; Vin_ext_12v_gen is either Vin_12v_ext or batt_v; 5v_reg - is either generated by an on board regulator or ...
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46 views

resistor placement for zener diode for over voltage protection

i have searched in over voltage protection (like mosfet ) , i wanted to use zener diode parallel so it wont dissipate power unless in over voltage protection , but its power is low so i read that i ...
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Input circuit for MCP3004

I am designing an ADC board for Raspberry Pi using the MCP3004 ADC chip. Please see my circuit below. This circuit is intended to measure voltages form 0 to 10V, to have overvoltage protection (Vin&...
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42 views

Protected Li-ion batteries charging / discharging in parallel?

since there is no longer good source of high quality pouch flat type Li ion cells, I am considering to use high new smartphone batteries from service packs. I need bigger capacity - about 10 - 20 Ah,...
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38 views

How do surge protectors interact with existing circuit protection?

I recently bought a power strip with a surge protector and it came with this warning. Do not install this product if there is not at least 10 meters (30 feet) or more of wire between the ...
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54 views

Limiting voltage transients with a TVS diode

My goal is to suppress transient voltage spikes from damaging the 5V, 600mA Step-Down Voltage Regulator D36V6F5. I believe the transients are a result of high inductance in the wires between the power ...
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55 views

Transient current capacity of sacrifical Zener diode

The common wisdom is that Zener diodes are suited for only very low power surge protection because of their low current capacity. But what about where it was used as a sacrificial device for clamping ...
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68 views

Has there ever been a case of overvoltage in a power grid?

Every now and again we read about blackouts, where the voltage of the power grid drops and the infrastructure is paralyzed. But have there ever been cases where the power grid experienced a massive ...
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43 views

How to select components for crowbar circuit?

I need to make a protection circuit for over voltages (protect from more than 5V, protect from 6V to 30V) and current(protect from more than 5A) Could you please suggest components for following ...
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90 views

Overvoltage and reverse polarity protection

There are two well-known circuits well described in the Internet, including this site: Reverse polarity protection with P-channel MOSFET; Overvoltage protection with SCR and Zener (so-called "...
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73 views

Crowbar circuit fuse placement

I'd like to use the below circuit to protect my device from overvoltage. simulate this circuit – Schematic created using CircuitLab D1 is rated to 15V. SCR1 is supposed to be ON Semi MCR100-8G ...
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59 views

Overvoltage Protection Circuit for 5V limit

I found surfing internet an overvoltage protection circuit where I need to choose the value of R1 and D1 to set the value of the trip voltage to protect the load circuit. How should I correctly ...
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1answer
88 views

GPIO over voltage input protection

I want to design a circuit that can protect GPIO of the microcontroller from high voltages.the GPIO connects externally to mechanical switch. So my approach was to use zener diode to clamp the high ...
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1answer
102 views

Trouble understanding overvoltage protection circuit

I am working on a DALI circuit and came across this app note. App note gives a schematic which is supposed to protect the circuit in case someone connects 220 VAC wires to the DALI lines. Schematic ...
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1answer
240 views

Designing an effective power supply for embedded products

I'm currently designing several embedded microcontroller products to be powered from a wall outlet. I plan to use wall-wart power supplies to give an input of approximately 5-9V DC but I want the ...
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1answer
137 views

Analog input over-voltage protection using Schottky and Zener Diodes. Can it work?

I'm developing an analog input module based on TI's ADS8668 and want to protect the input channels from over-voltage. According to the datasheet, each analog input channel withstands voltages from -...
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3answers
149 views

Designing reverse and overvoltage protection at 3.3V

I have a barrel jack powered design that I'm making, but I would like to prevent damage in the case of reverse polarity (sleeve is positive instead of negative) and overvoltage (plugging in a 12V ...
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87 views

If an MCB protects from overcurrent, which device protects from overvoltage?

In the context of whole house protection devices used in distribution panel, if an MCB protects from overcurrent, which device protects from overvoltage? Surge Protection Devices (SPD) can only ...
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132 views

Polyfuse with Crowbar for Over Voltage

I am looking to add overvoltage protection to a circuit of mine. A standard way of doing this is with a crowbar circuit with a fuse to blow when tripped, thus disconnecting the circuit. However, I ...
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105 views

Running 3.3v over a USB, How to protect against 5V input

I am running 3.3V over a USB cable from circuit A to supply voltage to another circuit B. I am worried that someone may plug 5V into this line and fry my board(s) There are two scenarios. 5V ...
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58 views

How to protect against line transients?

I am designing a circuit that can detect if a cable is connected to mains voltage (e.g. via an external relay or switch). The device will be installed in electric cabinets. The circuit is tested and ...
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88 views

Radio module resetting when fluorescent tube switched on/off

I have a PCB powered by an IRM-30-12 power supply (230VAC to 12VDC). On this PCB, I have a MRF24J40MD from Microchip and a Udooneo to drive it + a 5VDC regulator and the 3.3VDC of the Udooneo. After ...
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73 views

Should I include over-voltage protection for a 3.63V max device using a Lithium-SOCl2 3.65V battery?

When designing an ultra-low-power device that is powered by a primary lithium battery, is it necessary to include over-voltage protection? Specifically, I am using a Microchip (Atmel) SAML21J which ...
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2answers
510 views

Voltage monitor circuit (reverse polarity protection with high voltage cut-off)

I want to make a circuit which performs these tasks: 1) Protect the load against reverse polarity. 2) Protect the load against over voltage. Load = Raspberry pi Reason for this circuit - Pi is not ...
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1answer
115 views

How do I size a zener diode for use as a freewheel diode for a ZVS induction heater?

My electronics experience is "hobbyist" and I'm in some new territory with this question, so forgive me if this question turns out to have an easy answer or prove to be dumb. I have a basic ZVS ...
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75 views

Why do protective relays have a delay?

6I am a software engineer with a small amount of experience in electrical engineering that has been tasked with designing an embedded OS for a IDMT relay (uni project). However, I don't understand ...
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2answers
213 views

Protect ADC input from over-voltage with Schottky diodes

Alan Walsh on this article has suggested using Schottky diodes to protect ADC input from over-voltage, the circuit looks like below: simulate this circuit – Schematic created using CircuitLab ...
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125 views

Overvoltage Protection for Battery Charger

I'm trying to come up with some form of precise overvoltage protection between battery chargers and batteries between 12V and 48V batteries. I have 12 and 24 sorted using different methods: crowbar ...
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0answers
103 views

Overvoltage protection circuit - Serial zener diodes and op-amp

I need to prevent people from plugging in batteries with incorrect voltage. The 2 cell LiPo with voltage range from 6.4 to 9.8 V is alright, EN=1. But 3 cell LiPo is too much and I need the below ...
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2answers
276 views

Why would this (simple) over voltage protection circuit raise the output voltage?

as a beginner I have recreated this circuit: I found it in this guide, and I was hoping it would work as intended but instead it gave me some weird results. I connected power to the circuit and ...
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3answers
247 views

Overvoltage protection with zener - How do you get a sharp knee clamp for analog input?

I'm working with an MCU that sees a 0-5V input range. I have a possibility where they may accidentally see 12V (user error). My problem is this analog input using a 5V Zener has a knee that isn't as ...
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63 views

Smart undervoltage protection

what is the simplest way to regulate the min DC voltage in a circuit? ...
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2answers
172 views

Understanding STEVAL-ILM001V1 DALI transceiver schematic + adding protections

I'm working on implementing a DALI bus interface circuit. DALI has a few specifics that make this tricky: The device should draw at most 2mA when receiving, it transmits by shorting the bus (250mA is ...
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1answer
88 views

Over voltage protection for a buck controller 24V in. 4-5V out

Please see Image below, if the output votlage here is 4-5V with current out 3A-15A(depending on LOAD). Could I stick a Zener diode to clamp any over voltages to protect the load from over voltages? ...
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1answer
83 views

USB Overvoltage and ESD protection

lets say, i am using a LTC4361 ic to protect an usb device from overvoltage and -current. Top Left is GND, below is VBUS, +5V is protected output. How would i deal with ESD protection for the 5V line?...
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80 views

Will my zener diode work again with a polyfuse after a overvoltage?

I am trying to make a simple overvoltage & current limiting circuit for my PCB. I made the following circuit. The zener will break down and conduct current to ground. Since its resistance has ...
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1answer
117 views

overvoltage protection of opamps

simulate this circuit – Schematic created using CircuitLab I see diodes arranged like D1 and D2 sometimes used to prevent nuisance tripping of a power supply's internal overvoltage protection ...
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3answers
118 views

Over-voltage protection system for a 7 - 20 A Load with 4 - 5.5 V output from PSU

The power supply used on the product, is a DC-DC buck controller 24 V in (3 - 5.5 V out). I need some suggestions to help protect a load (LED Display) which draws roughly 5 - 15 A the power supply on ...
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2answers
100 views

How much buffer room is required for a varistor?

I am working on a circuit board design that uses a fuse resistor for protecting from short circuits and a varistor to protect from over voltage. The board is a simple power supply of only a few watts. ...
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2answers
128 views

Voltage regulator and loss of ground

I have a design that has a +24VDC supply, a 7805 voltage regulator converting it to 5 volts and then a microcontroller and some peripherals behind the regulator. The design and the 24V supply ...
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1answer
120 views

Digital voltage stabilizer relay diagram

I am using this voltage stabilizer relay diagram below, which provides a 16 step-up level. I need to edit it, so that I can made it to work as step-down in case of high voltages such as 245 and above. ...
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201 views

How to shutdown SG3525 inverter with op amp

I'm trying to make an overload protection and low battery indication circuit for my 50 watt inverter. I have made an overload protection circuit using op-amp, but when an overload event occurs the ...
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1answer
73 views

Input protection on a DC jack

I am designing an battery powered instrument with around 20-40Ah 3S li-ion batteries in it along with a 10A 3S(12.6v) external charger. Due to ease of availability and the current capacity I have ...
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0answers
80 views

Over voltage and under voltage with time delay device

I made a circuit as shown in the attached picture. It is an " over voltage and under voltage protection device with delay time" it worked properly at the first, but later it stopped giving any output. ...
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85 views

DMX protection circuit (diode clipper)

TL;DR I’m building a board that bridges the common types of DMX connector (various forms of XLR, RJ45, tails and product-specific terminals). There is a possibility that someone could accidentally ...
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0answers
20 views

Voltage applying to cpld I/O pin while VCCio isn't connected

I have a pcb based around a coolrunner II cpld . My problem is as follows. An other ic generated at it's output a logic '1' (around 3.5V ) and the signal was driven to an input pin of the cpld while ...
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1answer
54 views

LED current source circuit design concerns

TL;DR: Read the bulleted list below. I am designing a simple constant current source to power up some LEDs inside arcade buttons. My project consists of 20 of these buttons. Every button is ...
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1answer
178 views

Crowbar Circuit for 35V OVP - What parts should I use?

Please excuse my confusion, because I really don't understand what the "150mA max continuous cathode current" means on the datasheet for the LM431. I'm also not sure it'll work in the crowbar circuit ...
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1answer
139 views

LTC4366 killing MOSFETs

I designed a circuit around LTC4366 as per the picture below. However numerous MOSFETs have been damaged and become useless. Mosfets used : STH12N120K5-2; IXFT50N85XVH; STW13NK100Z - All are rated to ...