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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14 views

Help troubleshooting diy battery charge/protect/step-up circuit

I am following the schematic below trying to put together the circuit for a battery charger with over/under voltage protection and 3.7 to 5v step up. I have populated only the battery charger part of ...
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10 views

[Digital input over voltage protection solution - varistor or TVS]

I have to select the best safe solution to protect a 5V input. Below 4 solution that I have designed to protect my 5V input against over voltage using varistor and TVS. Different solution are ...
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43 views

Over voltage and reverse polarity protection

I was trying to make an over voltage and reverse polarity protection circuit and create a PCB that I can easily use in some of my projects. My level of electronics it's not so good, and that's why I'm ...
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58 views

Protection circuit for fake-USB device

I'm developing a set of sensor modules that connect to a controller board, that's also developed by me. Though the communication between controller and slaves is RS-485, I'd like to use a USB-C ...
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673 views

How does this overvoltage protection work?

I was looking around for low cost and effective overvoltage protection, and I found this from this page: With this part list: RXE025 - 250 mA PTC resettable fuse Zener diode – 5V6, 1 watt Resistor – ...
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66 views

Problem with overvoltage protection circuits limits

I have a circuit which input voltage shouldn't exceed 50 V, I can't use neither of available overvoltage protection circuits because of the limits each have; Crowbar circuit. While this is a good ...
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74 views

MOSFET Drain - Source overvoltage protection

I am developing project of MOSFET switch that is going to be used as power switch device in application with 12S li ion battery. To keep power wastes in the minimum level, I have to provide the lowest ...
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214 views

Crowbar circuit design: choosing the correct parts

I've designed a crowbar circuit with the aim of protecting my circuit from overvoltage (it cannot exceed 15V) and reverse polarity protection. Looking online,Ii've found that a good solution for ...
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56 views

Overvoltage protection for DC controlled Device

i've designed this schematic using a simple buck converter (LM2596) for my board that powers up some leds and board peripherals. The board will work at 5V with maximum current draw of 2.5A. Now, as ...
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65 views

Is ADC over-voltage protection needed when input isn't external?

In a situation where an ADC is measuring an internal voltage node rather than an external input (where one has little control over input voltage), does one need to implement some over voltage ...
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55 views

Issues with simple NiCd battery charger circuit

Inspired by this circuit, I'm trying the following one for charging 2 NiCd batteries: simulate this circuit – Schematic created using CircuitLab There is a current limiter part, with a red LED (...
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38 views

Why do these diode connected JFETs not clamp my output?

I've attached the LTspice image for some clarification, perhaps someone can see where I've gone wrong. I need to use JFETs to reduce the leakage currents (the outputs are going to an 18 bit ADC). Why ...
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102 views

Please help explain how OVP works using voltage divider

I tried to convert an old 12.09V LiteOn power supply to an adjustable voltage power supply by installing a pot to change the voltage divider for its TL1431C shunt regulator. I was able to make it ...
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48 views

Is it possible dimension a braking resistor according to a specific stopping time for a DC motor?

Assuming that a DC motor is running at 1200 RPM and there is a power cut, the motor will stop in 40 seconds. Now when the power cut occurs, a braking resistor is switched on. What would its value be ...
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29 views

Overvoltage protection for low side MOSFET using TVS or Zener

For the following overvoltage scheme taken from this document, it appears that a zener diode is used to turn the gate of the MOSFET on when the drain voltage exceeds a certain value. For this ...
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85 views

Getting a higher voltage from TL431 in a crowbar circuit

I want to protect a circuit from overvoltage using crowbar circuit, the input voltage shouldn't get above 50 V. TL431 output is 36 V max, can a zener diode in series like schematic below protect the ...
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1answer
57 views

Protecting BJTs from overvoltage

I'm building an electronic load and I need to protect the transistors from overvoltage. This is the over-simplified version of it: simulate this circuit – Schematic created using CircuitLab I ...
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27 views

Frequency of the surge voltage

When analyzing an electrical circuit, and in the occurrence of an impedance mismatch between the supply voltage and the load (connected through a cable) + a high switching frequency, reflection ...
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41 views

Bypass diode 1N5400 series on 48v system

I want to protect my dc motor controller from voltage spikes due regenerative braking. Battery is 48v (54.6v at full charge) li-ion chemistry 100A peak, with "cutt-off protection BMS" from ...
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1answer
44 views

Charge LiPo battery with protection directly through dev board

I am just buying some LiPos (3.6V) and charging circuits for a project. The batteries come with overheating, over-voltage, over- and undercharging protection circuitry. In the reviews, someone ...
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1answer
74 views

Adjustable CC/CV supply with voltage and current limiting having no output voltage at low voltage levels?

Im trying to create a power supply with an addjustable output between 0-12V or 0-3A (CV and CC adjustable). To make sure that the components don’t get damaged I'm trying to implement a protection for ...
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89 views

Do I need >5V power supply to adequately protect against overvoltage >5V? Seems contradictory

My circuit requires 5 volts and roughly 4 amps. I am using a 5V/10A power supply. I would like to protect against overcurrent and overvoltage (>5V). Protecting against overcurrent seems ...
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82 views

Simple and compact Over-Voltage protection with fuse and resistor

I know there are many techniques to protect over-voltage on the power supply. However, it does not apply to my case as it only provides single polarity voltage protection. Additionally, I want to ...
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1answer
65 views

18650 battery pack with “dead” cells, other cells still usable?

I have an 18650 battery pack (12p20s so 240cells) with 2 parallel groups which recently "died" (voltage is 0v or very close to 0v (0.09v for one of the packs 0.0v for other parallel group). ...
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69 views

Zener diode voltage limiter for Intrinsicaly safe application

I am designing a product that should meet ATEX requirements (Intrinsically safe design). Part of the design is a voltage limiter (overvoltage limit of buck-boost converter). Typically Zener diode is ...
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19 views

Connection battery charger IC to battery protection

I'm trying to design a battery charger with protection for 2 cells in series. I'll try to work with this charger: together with this protection IC: Sorry for the dumb question but I'm quite new in ...
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1answer
84 views

How to design a power distribution board? [closed]

I want to design my own power distribution board. But I don't know where to begin and key points. I plan to supply the board with a Li-Po battery (11.1 V, 14.8 V) and the board must supply 5 V and 12 ...
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67 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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51 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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37 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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24 views

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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140 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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86 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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93 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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18 views

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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43 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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78 views

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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34 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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29 views

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
123 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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84 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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1answer
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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1answer
82 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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52 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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129 views

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
42 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
52 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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42 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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81 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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62 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?