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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77 views

Bricked STM32 with Read Out Protection Level 1, can't disable it

So I was testing the boot option bytes of my Nucleo32 STM32G431KB board and somehow my Nucleo board is in Read Out Protection level 1. STLink Utility is unable to revert it, I get the error "Read/...
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29 views

ESD protection - delay time

I am wondering about situation, where there is an ESD to specific part of circuit, conatining IC. As I know TVS diode has defined delay time - it will not protect immadiately. My question is - what is ...
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51 views

Diodes in input protection circuits

I'm studying this protection circuit that protects a microcontroller from inductive transients, switches, and other things in a small aircraft, which would be similar to a car/motorcycle/boat in that ...
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50 views

How to prevent Current Limiting Circuit failing short?

I am utilizing what I believe to be a fairly typical current limiting circuit at the input of a DC/DC converter. I am driving the converter from a battery so I can never exceed a certain current or I ...
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81 views

Reverse polarity protection in PCB design

I've fried the controller on this PCB when by accident connected 24V supply in reverse polarity. The PCB includes a SS34 schottky on a positive side. However the controller still got damaged (...
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67 views

What is the problem with connecting a negative voltage to an op amp's negative lead while the possitive one is grounded?

I'm reading a manual on op. amps that presents the following schematics: And says: [Context: Vin goes from -0.1V to -1V] When Vcc is powered down while there is a negative voltage on the input ...
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64 views

When is a fuse used in tandem with a breaker/MCB?

I have observed that at the input (supply side) of some electrical units, only MCB is used for overcurrent protection; whereas in other units, a fuse is used as well as MCB at the input side. Why and ...
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40 views

What does “1 second short circuit protection” mean?

In the datasheet of R1SE DC-DC family I read: Short Circuit Protection (SCP) below 100 mΩ 1 second What does it mean? After 1 second of short-circuit the device will burn? What kind of "...
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68 views

USB reverse polarity protection - MOSFET

I am thinking about a relatively cheap and simple protection against USB reverse connection/reverse polarity. At the moment I am thinking about P-channel MOSFET, with the drain directed towards the ...
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58 views

Hot-plugging power kills switch-mode converter

We have a small IoT device, that runs of an external 24v DC power supply brick (https://www.rapidonline.com/tt-electronics-t6367st-24vdc-60w-installation-smpsu-85-3795) This 24v supply connects to the ...
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89 views

Back to Back and Ladder Protection Diodes

I'm considering replicating this schematic from a paper (https://ieeexplore.ieee.org/document/5062317). The idea of the circuit is to measure the capacitance of a transistor between the Drain and the ...
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755 views

How to choose protection resistor for I2c devices

Note : I am a beginner. I noticed on the STM32-410RB datasheet page 100 (https://www.st.com/resource/en/datasheet/stm32f410rb.pdf), protection resistors were used in series on the SDA and SCL line. ...
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47 views

MicroSD with STM32 and SPI mode - pull-ups and EMI filters

In the context of using the STM32F103C8T6 microcontroller I wonder I am thinking about the most practical and relevant method of the microsd application in the device from the point of device security....
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38 views

Starter engine reverse voltage/current

I am currently eyeing installing an electric starter to my pocket bike 49cc engine. This question is purely about the electrical part of it, but I am going to give a little context. The starter engine ...
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44 views

ESD protection for power input with several fused branches

I'm designing an industrial board that will be powered with a +24V DC. On the PCB there are several fuses to protect each branch against over-current/short-circuit. Example: simulate this circuit &...
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51 views

Is this design feasible? Door-open warning light circuit with safety interlock switch and general SPDT relay on wall voltage (120VAC)

I am trying to design a very simple system for my workplace that turns on a warning beacon light when a swinging door is opened. My current thinking is to use a non-contact magnetic safety interlock ...
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68 views

MCP73831 charger - how to control low voltage cell

Does the MCP73831 have a way to set a protection to shut down the main output if the supply voltage is too low? I would like to implement (without coding) a protection which disconnects the cell if ...
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How to protect the circuit from Ethernet ESD, overvoltage, etc

Creating a carrier board for a RPI Compute Module4, I am not sure how to protect the circuitry from possible ESD /over-voltage coming through Ethernet connector. In normal circumstances, I would apply ...
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35 views

Reverse voltage protection for lithium battery charging module with smd component(s)

I want to add to this famous single cell lithium ion battery charging module a reverse voltage protection: I ended up with the following circuit (Load draws up to 700mA): Sorry, updated: My ...
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54 views

How to prevent a Lipo/Li-Ion-Battery from catching fire after a complete self discharge with a following accidentally recharge

From the following Youtube video (at 3:15min) I got that it is dangerous to recharge a Lipo/Li-Ion-Battery after it was completely discharged (0V), because it will catch fire. https://youtu.be/...
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61 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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89 views

Very fast short circuit detection

I am working on a high current MOSFET switch project. I would like to implement short circuit/overcurrent protection, that would be fast enough to prevent MOSFETs from blowing up. In the actual ...
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71 views

Name for PCB isolating tape (usually found in notebooks)

Looking for the name and, at best, part number for the tape usually used to isolate the PCBs, in particular inside notebooks (black tape on the pic below): My design is having through-hole capacitors ...
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46 views

Back EMF protection of a bi-directional inductive load

I have been researching this subject for some time now and I found three ways to deal with this issue but I can't make up my mind on which one is the best for my application. I have a high torque 12V ...
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77 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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42 views

Conditioning for automotive electronics [closed]

I have a simple application: convert an automotive throttle 0-5V line to 0-2.5V on a circuit near (and feeding into) a fan controller. Very loose maximum frequency is 10Hz. I reduced R1 because the ...
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59 views

How to protect a GPIO pin with a long input wire from transients?

I am building a custom doorbell system that will support multiple doorbell buttons and annunciators. I am using an Adafruit Feather and a couple of FeatherWings for each unit. The project can be ...
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48 views

How can I measure the reverse leakage value of a TVS diode?

Compared to the component's datasheet without protection circuit, for quality control purposes. Can I use a multimeter for that?
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105 views

How does a MOSFET gate resistor reduce ringing? [duplicate]

I desiged P-MOSFET for reverse voltage protection, without gate resistor. The reason that I tend to use it is protect from reverse DC voltage when someone connects the battery. Do I need a gate ...
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43 views

Reverse charge protection for parallel primary lithium cells (CR2450)

First time poster, long time follower here. I am looking into the safety aspect of using primary lithium cells in parallel. The reason behind using parallel cells is to increase overall capacity. In ...
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96 views

UC3845 flyback add a OVP (OVC) protection

I built SMPS based on this schematic: It's working nicely - I recalculated transformer and flyback to 24V, I used EI33 transformer with airgap (put 6 pieces of paper between halves of the core). I ...
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134 views

Help me identify this IC marked “CI” next to the LiPo battery. (It's not the charger IC)

The IC (descriptor U5) with its peripheral resistors (R55, R84, R59) is right next to the battery connector, on the path prior to connecting to the battery charger IC (which is the ISL9230). The IC is ...
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69 views

What to use for neutral protection

I need information on "the protection of distribution system through effective grounding techniques." I want to know the possible protection schemes for neutral as fault current or return ...
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81 views

Do capacitors provide ESD protection even if they are already charged?

I've read about ESD protection with capacitors and it seems that if one knows its limitations it could in some cases be a cheap alternative for or addition to designated ESD protection circuits. The ...
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29 views

Protection and charging circuit for LIR2032 or ML2032 battery

I am designing a tiny device with very low power consumption. The device needs a rechargeable battery which should be charged from USB. I have found LIR2032 and ML2032 batteries that can provide ...
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51 views

The Best Place for the Reverse Polarity Protection Diode

I have several RS485 devices. All of them are connected together and power by a 12V power supply. Each device has its own 5V voltage regulator. I want to use diodes for each of them to protect aginst ...
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34 views

Is it harmful to touch only one point in a 200V circuit

Consider an LED setup where several modules are connected in series so their forward voltages (~20V each) add up to something around 200V. The setup is driven by a Mean Well HLG-480-C2100 driver. Now ...
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96 views

How can I protect an analog output from high voltage?

I have a DAC output from my STM32 microcontroller. The DAC output gives 0-3.3V and I want to protect it from high voltage backwards, e.g if I apply e.g 30V onto the DAC output by mistake. Is this the ...
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57 views

Reverse current protection

I design a wearable, battery-powered device with a watertight enclosure. It will have a waterproof USB connector for battery charging. Here is a schematic. J2 is the USB connector, MCP73831 is the ...
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45 views

Choosing fuse for 2S li-po

I Have 2S 8000 mAh li-po battery I want to use as an external power source for my DSLR camera (Canon 7D Mark II). Previously, I failed to power it with power bank and DC-DC converter, most probably ...
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181 views

Can I assume input protection diodes in all modern ICs, even when not mentioned in the datasheet?

I use the A3906 motor driver on a board supplied by 8V. The µC on the board is supplied by 3.3V and is connected to the A3906 via the logic pins. I realised this is a potential pitfall, when supplying ...
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119 views

Implementing Active Miller Clamp

I am using UCC21732 gate driver IC. This has an external miller clamp, meaning the "Clamp" pin must be connected to the Gate of the external MOSFET. However, I want to build my own miller ...
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30 views

What breaker should I use to protect downstream?

I have a 16A supply connected to a junction box to split into a 16A feed and a 13A double socket. The issue is the 16A is connected to a load that will have high inrush current. I have protection for ...
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Circuit protection - Is this sufficient?

I have a situation where I need to test a PCB to make sure it is working correctly. This PCB has 2 power and 2 signal lines (and GND). The 2 power lines are 12V and 3.3V. The signals are all 3.3V. ...
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49 views

Is it recommended to add external ESD protection to devices that have internal ESD protection?

I have to design a system composed of a main PCB and enclosure (with multiple interfaces - UART, RS-232, SPI, I2C, GPIO) and an external interface board without enclosure (with only connectors for ...
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93 views

Quad SPI series resistors on lines for short circuit protection?

I am designing a circuit where MCU connects to LCD driver IC (FT813) using Quad SPI. Since there is a risk of Both MCU and FT813 pins becoming output at the same time with different values (i.e. one ...
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37 views

Current sense amplifier for overcurrent protection

I'm trying to compare the use of a current sense amplifier with a sense resistor for overcurrent protection of SiC MOSFET. Here is my schematic using INA210 current sense amplifier, UCC21732-Q1, and ...
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47 views

How does the TP4056 overdischarge protection work?

I want to buy this integrated circuit (IC) to charge li-po battery. TP4056 Type-C 1S 3.7V It looks nice for charging but I am afraid of the overdischarge protection of this IC because in the ...
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27 views

MAX882 battery protection

I am thinking of using the MAX882 IC to protect my battery from overdischarging. What I could not understand from the datasheet I provided is that, if I use the STBY pin to set a threshold for my ...
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111 views

How does the back-power protection of the pi function?

The Raspberry Pi HAT design guide states that it is important to build in protection should the user want to back-power the pi via GPIO. I believe I understand its function (to stop current flowing ...

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