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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54 views

How do these Zener diodes limit the maximum voltage seen by other circuit components?

This schematic is given in Texas Instrument's AN-1533 Application Note (Over Voltage Protection Circuit for Automotive Load Dump) On page 4, the author says that the D3 Zener prevents the cathode of ...
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22 views

Overvoltage and overcurrent protection to digital signal lines

I'm looking for a technology that protects digital signal lines like SPI, I2C, UART and general purpose I/O against overvoltage and short circuit. That is, protects the microcontroller's digital ...
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Over voltage protection circuit for Iphone devices

All powerbanks I have found are able to provide 5V, which is perfect for android smartphones, but not for Iphones, which have a nominal voltage of 3.8V. However, powerbanks of 5V may be used to charge ...
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31 views

Metal Oxide Varistor connection

How do I select the MOV for a multiple operating voltages. Consider the diagram below, when switch is in position 2-1 and 5-4 (both primary winding are connected in series), I can apply an input ...
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What is the best TVS/ESD protection for Wheatstone bridge circuit?

I have 150K ohm on three legs of Wheatstone bridge, one leg on human body (skin), bridge excitation voltage is 5V, differential amplifier is be used to read the differential voltage of the Wheatstone ...
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88 views

Type-C Non-Negotiated Power and 20V protection

I'm developing a 5V device and I use 5V for powering/charging the device. I googled the subject of course, and came to the conclusion that 5V device should have 20V protection in case there is some ...
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79 views

Over voltage protection IC keeps burning

I am currently working on a project where over voltage protection is necessary. I made a test circuit using an LP5300 (SOT23-6 type.) https://datasheet.lcsc.com/szlcsc/1912111437_LOWPOWER-...
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60 views

Overvoltage protection using opamp

This circuit is used for overvoltage protection, I can see that the two opamp are comparators that will output 0 or 5V depending on the input, but can't see how it is protecting from overvoltage. ...
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LVCMOS 1.8V PWM Out disabling Circuit

In our project, we have a 12V to 5.4V buck controller implemented with discretes. Buck controller has input PWM signal from ASIC. As part of protection, we have implemented a comparator(here i am not ...
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36 views

Li-ion built-in vs external protection

Many Lithium Ion batteries have an internal chip (a protection circuit I guess). Are External protection circuit (like the TP4056) really necessary due to internal chip? I can't find the answer on ...
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ADC Input Protection with 4-20mA

If you've got a 4-20mA transducer, powered by 14V, and you want to measure it, your analog front end might look something like this: simulate this circuit – Schematic created using CircuitLab .....
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33 views

Relays for switching circuilation pumps

I have a board populated with Omron relays (G5Q-1A4-EU DC5) and I want to use them to switch circulation pumps (https://imp-pumps.com/pumps/ghn/). Is the previous relay appropriate to be used with ...
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Automotive Load-dumps, ISO standards & Meaning behind datasheet

Im looking towards using an system basis IC for one of my designs (UJA1164A) and i noticed that under the features & benefits it notes that "Battery and CAN bus pins protected against ...
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1answer
88 views

5V Crowbar circuit using LM431 not triggering

I'm designing a crowbar circuit to to blow a 1A fuse, when the voltage increases above 5V. I'm using an LM431 and using the design in Figure 20 in the LM431 datasheet. I designed and prototyped the ...
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66 views

Overvoltage + Overcurrent protection

Our compliance agency believes that it is all too likely that a 50 V power adapter is used instead of our 5 V power adapter. Regulation wants a fuse which can protect from 50+ V, and not allow 15 W ...
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30 views

Stopping overvoltage with Solar on Lithium ion tool batteries for an audio application

I am using two Lithium ion tool batteries (18V) to get a 36 V line. When fully charged it is greater then 40V. As they are tool batteries, undervoltage protection is already built in. I want to be ...
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47 views

protection IC stopping battery from charging

So, I'm using an AP9101C as protection IC and MCP73811 as a charger IC for a single cell lipo like this: The load works fine and when I connect +VDC (5V), suddenly CO of AP9101C goes to 0 preventing ...
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51 views

Why does this N-channel MOSFET not turn off?

I was playing around on CircuitLab to see if I can add an overvoltage cutoff to the reverse voltage protection circuit in TIs slva139. Using a zener, I expect OVS to start rising beyond the zener ...
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Sustained over-voltage protection for a 1 MHz digital logic line

I am working on a board which is user-insertable into a DIP socket. Incorrect insertion is always a concern, and in this specific case insertion "shifted-by-one-pin" is especially worrying. What then ...
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1answer
34 views

Circuit Charging Sealed Lead-Acid Battery (NP1270M)

I have a project (remote gate opener...) I have made good progress but its the first time I have built a charging circuit so I have some questions I need help with. The battery I am using is a sealed ...
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2answers
37 views

How to choose the right clamp diodes for CT overvoltage protection

I have seen back to back diodes and TVS diode (no both at the same time) used for protection in current transformers. In my case, I have a CT signal with a DC offset of 2.5V. The max voltage I will ...
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30 views

Active transient voltage suppression clamp parts/design

I am revising a design that was originally specified with a SMBJ54CA [2] bi-directional TVS protection diode in front of an LM76202-Q1 [3]; this is in conformance with the design example in section 9....
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63 views

How to protect/enhance an LDO so that it can sink current in the event of an external wiring fault?

Background I'm designing a signal acquisition board and one of its parts has several differential op-amps which are not very good from PSRR standpoint. So they need a very clean power supply, and ...
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57 views

What is this MOSFET for?

What is this MOSFET for? First I thought it's some sort of over-voltage protection but right after this, there's Zener diode doing the same?
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Fault protection circuit

I've searched the electronics stackexchange site but couldn't find an answer for the following 2 questions: For a home project I'm designing a circuit that is powered by a 24V battery. This battery ...
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78 views

Voltage protection with 555 timer not working

Briefing I am using Multisim to simulate a circuit before building it. The voltage protection circuit with a regulator works fine and the timer circuit works fine as well separately. When I try ...
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47 views

MOSFET Gate-Source voltage in protection circuit

I'm creating board which is supposed to withstand OV/UV and reverse voltage. I've chosen LTC4365CTS8#TRMPBF(datasheet) IC to deal with this problem. In reference schematic for 24V input they are using ...
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Isolated Dc Dc comverter OCP triggers Output OVP on another converter with their inputs connected in parallel and common output ground

In a system we have a bank of isolated dc dc converters that feed a bank of bldc motors with their respective ESCs. These converters have their input connected in parallel to another identical one's ...
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64 views

Why is the maximum voltage of a surge, 6kV inside home wiring?

I was reading about the benefits and cons of series mode surge protectors vs MOV-based surge protectors for home use. First, why is the probability that a surge will exceed 6kV extremely low due to a ...
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87 views

Varistor - Place before or after the fuse? [duplicate]

What is safer? Before or after the fuse? In my case the varistor is 10mm, 275Vrms, and it is currently placed after a 250Vac, 7A, 20mm glass fuse. Would the varistor blow the fuse easily if placed ...
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65 views

Overvoltage protection Piezo Harvester

I have a piezo harvester, capable of creating spikes of 50+Volts. My harvesting circuit which will be connected to the harvester output, has a maximum rating of 20Volts. Therefore I need some kind of ...
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34 views

Multicell overvoltage protection with op amps, how to get rid of oscillating behavior?

Still a beginner in analog electronics, so excuse me for being inaccurate. Also I am playing with circuitjs@falstad.com which might not be the most accurate sim... I wanted to provide a very sharp ...
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270 views

Op-amp based over-current protection circuit not operating as expected

I am trying to make an over-current protection circuit using an LM358 opamp and an N-type Mosfet. I have only done it on Proteus simulation, not in real life. The problem I am having is that the ...
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37 views

14.8V LiPo Battery Protection

Disclaimer: This is my very first time I have to work with batteries so I have basically no idea whatsoever. I need to protect a 14.8V LiPo Battery from overcharging/overdischarging. I have looked up ...
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105 views

ADC protection best practice

Say you were wanting to measure a signal with a higher voltage than the ADC could handle. Is there some best practice or commonly used circuitry that goes beyond a simple voltage divider to protect ...
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47 views

Can I extend the allowed Vin range of a voltage detector IC with a simple zener shunt regulator?

I'm trying to solve a particular corner case in the behaviour of a system I designed. The issue can be boiled down to this: I don't want a particular LDO to operate if it's input voltage is below 4V (...
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87 views

exceed drain-source voltage on mosfet

what happens if I exceed the maximum rating of the drain-to-source voltage of an N-MOSFET I am using NTNS3C94NZ so 12 V in this case datasheet: https://www.onsemi.com/pub/Collateral/NTNS3C94NZ-D....
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125 views

Why Zener diode doesn't fire at specified voltage?

I have the following schematic, which would be used as a over-voltage and reverse polarity protection: simulate this circuit – Schematic created using CircuitLab Both D1 and D2 are rated at ...
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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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53 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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131 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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70 views

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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79 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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1answer
51 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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1answer
80 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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69 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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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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65 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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1answer
401 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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132 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 ...