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Questions tagged [circuit-protection]

A device, components, or safety measure designed to protect circuits from overvoltage, overcurrent, a combination of these; or the theory of same.

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What is the best practice for 2 inputs triggering one device

I am loving this site with so much knowledge. I have a slightly different request and from the notes, i have seen i am still a little confused. My project is I have a 24V source that when switched ...
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2answers
985 views

Overcurrent / short circuit protection for back to back mosfet ac switch

I'm trying to come up with a way to do overcurrent protection for the following circuit: My first thought here was to monitor the increase in voltage drop over one of the mosfets (M1) and via a zener ...
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2answers
72 views

Protecting analog pin from ESD strike

After reading some relevant questions on ESD here, I have come up with the following approach to protect some ADC GPIO pins on my lipo battery operated board that are open to external input, thus ...
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2answers
45 views

Battery powered circuit protection

I’m just curious what kind of protection you would typically expect to see on a battery powered circuit. Circuit in question is a simple 24v dc relay controlled motor. Main power source would be 2x ...
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2answers
73 views

Arduino NANOs sharing input signals and controlling Pixel Ring blowing up

We're a bit stuck on the following problem : We've connected a bunch (18 to be precise) of Arduino NANOs on the same +12V supply and they all share the same PWM output from another device (which goes ...
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2answers
246 views

Protecting external power lines from short circuit

Sadly i am only a software engineer with little electronic knowledge. I build a device with a mcu and a 5-pin connector (3.3v, Gnd, 3 data lines) on it. My mcu has a 3.3v supply pin which i connected ...
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2answers
122 views

Water level controller

I want to design water level controller with PIC micro controller. Simple working is: two inputs 1) tank_high and 2) tank_low which pulled up initially, and one wire will be connected to lowest point ...
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1answer
46 views

Recommendation for series protection resistors on CAN bus?

When implementing an RS-485 interface, I tend to follow TI's recommendation in the SN65HVD75 datasheet to include \$10 \Omega\$ series resistors on the A and B lines. The TVS diodes I'm using clamp ...
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1answer
426 views

Dimensioning SCR crowbar circuit

I need to dimension an SCR crowbar circuit to reach a certain level of protection against overvoltage, without increasing much the complexity of the circuit of my control card. The need is to protect ...
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1answer
138 views

oscillation in overcurrent shutdown circuit

I've tried to design an overcurrent shutdown circuit, what turned out to be more complicated than I thought. The specifications: PSU from 5V to 40V Shut down at currents >= 1A At most a Watt or so ...
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1answer
76 views

Use of internal PCB ground plane as ESD baseplate/EMC reference plane of product in plastic enclosure

I am designing an electronic product which will be housed in a plastic (non-conductive) enclosure. There are a number of, mostly shielded, I/O cables (Copper 10/100/1000Mb/s Ethernet, USB 2.0, RS232, ...
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1answer
64 views

How can I simplify my design for a Surge Protection Device (SPD)?

I have found a basic design for a SPD and I would like to simplify it. However, I have little experience designing SPD circuits. This is my parallel type SPD circuit with embeded LED indicator: In ...
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1answer
60 views

high power - overvoltage protection

I am designing a circuit to protect a load from over-voltage. The voltage at the load must be around 380VDC and the current consumption will be around 2A. In normal operation the Power Supply must ...
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1answer
105 views

In a DC circuit, are there any reasons for wiring overcurrent protection such as fuse or pptc PHYSICALLY near the load?

In a DC circuit, are there any reasons for wiring overcurrent protection such as fuse, pptc, etc.... PHYSICALLY near the load(or inside it)? By wiring "physically near", I mean in the power wire going ...
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1answer
203 views

Calculating energy of transient/surge handled by metal oxide varistors (MOV) or surge suppressors?

As I get to know more about the MOV operation, there are more things needed to understand. My MOV (V420La20AP) has Varistor voltage of 680 Vrms (10%) at 1 mA, and maximum clamping voltage of 1120 V ...
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1answer
41 views

Wiring Up a Li-Ion Battery (Band 2)

I have a Li-ion battery that I pulled from a MS Band 2. It comes with a protection chip, which I am having trouble with. The chip has 4 accessible pins, labeled "P+, K, T, P-". I've tried every ...
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1answer
69 views

Earth& neutral voltage detection

Can someone suggest me circuit to detect the earth to neutral voltage. I would like to trip relay coil using microcontroller if earth to neutral voltage exceeds 3v. There are device RCB and RCBO ...
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1answer
24 views

TPS2559 TI, current switch for circuit protection

I'm researching a current limit switch but I am a bit confused. I need an IC that works as a current switch. I have a battery with charging and protection at one end, and buck boost on the another. ...
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1answer
48 views

Charging devices with different max voltages

I have a project that requires me to make a portable power pack that can be charged up and then power different devices. The product needs to have two USB charging ports and hold around 7Ah. The ...
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1answer
94 views

cheap charge management + protection circuit or fuel gauge + protection circuit

I would like to know if it is possible to have in the same package a fuel gauge ic + a protection circuit for lipo battery, or a charge management + protection circuit, in the same package. I have a ...
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1answer
60 views

How to decide earth trace width in protection circuit?

I am using the earth trace for protection circuit in telecom system. The protection circuit includes MOV, sidactor & fuse. So please suggest How to calculate the Earth trace width.
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1answer
134 views

A couple of questions about relationship with transformer, ELCB/RCCB and MCB

Q1. Which will be the correct way between circuit 1 and 2? Q2. For circuit 1, the transformer looks like not protected by ELCB and MCB. If short circuit happen after the MCB, the transformer will ...
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0answers
47 views

Testing eurorack input protection

I'm building a eurorack synth module, and I'm about to do the final tests on the design to make sure that the module cannot be destroyed (electronically, using what's available in the rack, so ...
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0answers
75 views

High power / high current clamping circuit

I am looking for ideas on how to clamp high energy surges in the input of a high current / high power system. The input to the system is 24V. During steady state, the system sources 85A of current ...
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0answers
61 views

Dual diode connection for return path

I want to use the following dual diode for the return path with a fuse. The diode is dual with each diode rated 25A, the cathode is the same, which means I have to connect it like in the figure? Do I ...
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0answers
92 views

How to protect a buck DC-DC being backfed from the load (e.g. a battery as a load)?

Background I want to design a DC-DC adapter that is foolproof and has some protections in place so that it doesn't accidentally damage the somewhat expensive equipment downstream. Here's what I have ...
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0answers
205 views

Tp4056 overcharging

I have combined five 18650 cells in parallel and i am charging them using a single tp4056 circuit . The problem i am facing is that the module keeps on charging. I had to stop the charging manually at ...
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0answers
93 views

TVS protection burnt too easily

It's about an year that I'm using TVS diodes to suppress spikes from the AC motors (240V - max 240W) that drives my roller shutters and protect the solid state relay that actuate the motor. What is ...
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0answers
64 views

Help in identifying two parts

I need to identify two parts that I need to replace, but I'm having a hard time doing it. These are the parts: Part 1: From my research I think it is a trigger switch (http://www.jiaben.com/en/pro....
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0answers
148 views

LT4363 High surge stopper shutdown at start up

I was asked to protect a DC/DC Buck converter against overvoltage and overcurrent event. During my research, I found the LT4363-2 component from Linear Technology that is defined as a High Voltage ...
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0answers
286 views

How to protect MCU IO and 5V from shorted +12V

I would like to protect an MCU from 12V being shorted either to IO or it's 5V supply. This is very similar to the question asked by kamil here: How to protect microcontroller board 1-wire from ...
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0answers
116 views

Identifying a input protection diode from a power supply by a photo

block schematic is . And connector photograph is . and broken element is . It seems to be TVS (Transient Voltage Suppressors) diode. Maybe, %20 unidirectional. Because, there is a mini hole in ...
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0answers
2k views

Speaker protection using only zener diodes?

It is crucial to match amplifiers to speakers correctly and use them with care. But in some cases you want extra protection from blowing up the speaker. I have thought of a ridiculously simple idea -...
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0answers
333 views

over-heating with AMS1117-1225L

When connected an external voltage to vout of this 5v regulator, the chip get very hot. I connected a 4v to its Vout, and it draws 500ma. The protection diode from vout to vin doesn't help. My doubt ...
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0answers
160 views

continuous DC voltage across output pin of an IC (DAC output)

I would like to ask you one question. Actually in the automotive there is chance of 20v or 5v continues output come across output of my IC (PGA400)i.e output of DAC. I would like to know in general ...
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0answers
57 views

How the oscilloscope input voltage rating is independent from attenuator setting

Since I'm taking part in a quite interesting educational project that incorporates the design and testing of the analog front-end of a relatively high speed ADC (up to 200 MSps) I've been studying the ...
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0answers
26 views

Seperate protection circuit for charger and system for Li-ion battery

I'm thinking of using the BQ2971x for battery protection. http://www.ti.com/lit/ds/symlink/bq2971.pdf One thing that anoys me is that most batterys (18650 Li-ions) usually have a lot higher ...
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0answers
76 views

Impedance of Bus Bar vs Wire

My question was simply. If a meter of wire has impedance of 1 uH. What is the impedance of a meter of bus bar? yesterday: To make it simpler. The longer the leads of SPDs (Surge Protector Device) ...
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0answers
61 views

Protection against ESD/EFT/Surges

One of my project architectures looks like this: GPIO / 595 output / 12 VDC wire lengths will not exceed 25 cm. I have faced MCU lockup issues due to EFT in the past and want to make sure this ...
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0answers
20 views

Lion Battery Shutdown Mode and Wake on Charge

I'm currently designing a BMS that doesn't rely on a TI bq-series IC for gas gauging, protections, etc. So far, I have analog circuitry handling over and under-voltage cutoff, overcurrent cutoff, ...
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0answers
45 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
36 views

US/Can - Maximum current in a single circuit in a 100A panel

I hope this is the right sub... I have a 100A pony-panel in the garage. I'd like to have someone add a wall plug for EV charging, ideally a 14-50, but I'd settle for a 14-30 if need be. I seem to ...
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0answers
56 views

chances of A4988 motor driver creating back current through the STEP and DIR pins

I am trying to drive 2 stepper motors using A4988 motordrivers and I am using the following circuit diagram as shown in the image Only change from the above circuit diagram is that I have not ...
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0answers
42 views

How can I build my own over voltage protection circuit up to 480 VAC

I am rigging up a portable test panel, will be using a true-meter APM that will do up to 600 VAC or 600 VDC. I would like to be able to use it to measure typical U.S. 120 VAC or 240 VAC and 480 VAC. ...
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0answers
252 views

Circuit protection incorporating a Transient Voltage Supressor and Polyfuse

I want to protect some microprocessor equipment ( 5.0v, max 700mA ) which is powered by usb cell phone type chargers from damage due to such things as polarity reversal, over-voltage, power surges etc....
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249 views

Resettable fuse failure

I have a 1.1A, 33V resettable fuse in SMD 1812 package. To test it, I connected a 6A 20V source across it. It went up in a flame that lasted a few seconds. Should I conclude that the fuse is out of ...