Questions tagged [esd]

ElectroStatic Discharge, it's caused by accumulation of electrostatic charge as a result of rubbing, and can damage semiconductor devices like integrated circuits.

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62 views

ESD protection & Current limiter circuit flawed [on hold]

Im working on an EEG, and i implemented an ESD protection and user current limiter circuit , the schematic is For NPN i am using BC547 and for PNP i am using BC557, the first 10p and 100p(C1,C2,C3) ...
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68 views

Should I connect the computer VBUS line to the 5V line of the board?

I am doing a project that needs USB communication with my microcontroller. On the board there is already a 5V power supply. I would like to know if it is correct to ...
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1answer
46 views

Unidirectional vs Bidirectional TVS diode for ESD protection UART bus

On my board comes a UART line with a voltage of 3.3V. To safely communicate with the controller on 5V, I use a level offset based on BSS138 transistors. My goal is reliable ESD protection of the UART ...
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87 views

When should ESD Protection Diodes be used?

I'm working on a heated glove project that uses a Buck-Boost converter to step-up/step-down the voltage across the heating element. This is something that has just occurred to me, but I'm not sure if ...
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3answers
61 views

Confusion about TVS-wiring with RS-485

I'm currently looking into securing my RS-485 connections against ESD. My current understanding is that a TVS diode is put between the data line and GND, so that any discharge will be shorted to ...
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1answer
164 views

I keep zapping mosfet and I don't know why

After asking collagues, trying a few variations and spending days on research, I figured out I could ask there as I am running out of ideas. The most similar discussion I have found is: mosfet is ...
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1answer
60 views

The Thermal relief consideration for TVS diode (for ESD protection)

I am designing a print which has some mircofit connectors, I have placed TVS very close to the connectors on the print and the ground pad connected with a GND polygon directly, this polyon connects ...
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24 views

Can any of the below damage a SIM800L module?

I was developing a simple circuit using an Arduino pro mini and a SIM800L when I understood that SIM800L's Vcc and Gnd pins have been shorted. I tested short circuit using the continuity and resistor ...
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1answer
81 views

Placement and values for ferrite bead/capacitor ESD protection / transient suppression filter

I've been researching but found it difficult to find a clear answer on this. I need to add ESD protection to my circuit, in this Texas Instruments video it talks about combining a TVS diode with a FBC ...
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1answer
64 views

Should isolated GND be tied to logic GND to prevent ground drift?

In an industrial environment, let's say you have an isolated interface that connects to an external sensor or device. This interface separates both logic signals to your main board as well as GND and ...
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2answers
52 views

How to connect the GND with the metal case of the robot

I have a PCB design inside a metal case of the robot. The robot is mobile, it moves on wheels. The problem is how to connect the GND with the metal case of the robot. Direct connection is not safe, ...
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1answer
55 views

ESD protection diodes on audio inputs / outputs?

I'm building a digital audio device with 1/4" stereo in and outputs that connect to a CS4272 codec. I'm wondering if and where I should place esd protection diodes. Pictured below is the analog part ...
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1answer
50 views

How to harden/prevent ESD in a circuit?

I've designed a simple circuit with three LEDs in series with a matching resistor, all powered by an IC. I want to make my circuit less susceptible to electrostatic discharge since it will be ...
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67 views

What is the purpose of R1, R2 in this ESD protection circuit

What is the purpose of R1 and R2 in this circuit? Is it required? I have seen in documents like https://www.onsemi.com/pub/Collateral/AND8169-D.PDF where no resistors are shown in the example ...
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1answer
61 views

ESD Mats failing with constant monitoring system

Good afternoon, This is my first time posting here, and I apologize if I am doing anything incorrectly. I'm already a member on StackExchange so I thought I would stick to this website for this ...
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176 views

What is the purpose of this 5 V protection circuit?

I'm working in the OEM company and I want to know what the purpose of the below circuit is. Whether +VCC5V0 or -VCC5V0, Q8 is off so I don't know the purpose of this circuit. It should be a ...
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70 views

transient protection for 0.5W laser diode switching driver

I'm some way into a project which involves switching 0.5W laser diodes at 100kHz, with a pulse of around 1us in width. I'm having issues with the diodes (which I don't have a datasheet for) failing ...
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1answer
42 views

Location for placing ESD components for UHD video

I am implementing ESD protection for HDMI video input. The HDMI video goes through a custom cable of ours, into a connector board attached to our enclosure, through an edge card connector, into our ...
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49 views

ESD Diode - clamping voltage

I'm trying to replace an existing ESD diode(PESD1CAN) in my application CAN circuitry due to some reasons, I've found an alternative ESD diode(RSB27C2), but compared to the diode that I already have ...
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11answers
5k views

How to safely discharge oneself

At work I have the problem that I seem to collect a lot of static charge as soon as I leave my desk and return. I am not quite sure why this happens. Strangely enough the effect is stronger the ...
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2answers
881 views

Some questions about antistatic wrist strap

The photo below shows an antistatic wrist strap grounded to the chassis of a PC through its alligator clip: I have three basic questions: If the chassis above is not earth grounded, does it make no ...
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1answer
136 views

Overloading of ESD protection diode on CAN lines through current during Bulk current injection - test

I have a design checklist question for a typical CAN circuit for an automotive application as below : The question is related to the ESD suppressor : "Was a capacitor parallel to the diode considered, ...
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1answer
69 views

Placement of RC filter used for slew rate limiting (for EMC)

I've seen RC combinations used on many circuits now which i believe have been included for slew rate limiting. They usually feed off to a connector. Do the placement of these matter in the circuit? ...
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1answer
157 views

How do anti-static wrist strap alarms detect a disconnection of the wrist wrap?

Sometimes I need to disconnect my ESD wrist strap, but forget to reconnect it again. Apart from improving my discipline to work more structured and more carefully, I wondered if there was any device/...
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1answer
654 views

Why is my ESD wriststrap failing with nitrile gloves on?

I have recently ordered some nitrile gloves for the cleanroom of which I am lab manager. I noticed that when I wear the gloves and test the ESD wrist straps, they are all failing. Can someone ...
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93 views

how to make an ESD sensitive circuit?

I have an experiment where I plug a sensor to an ESD (Electrostatic Discharge) protection circuit. Sensors are very expensive and very sensitive to ESD. I have tested my protection circuit it is ...
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67 views

Bulk Current Injection on CAN bus

I'm trying to understand how the Bulk current injection would look like on the CANH and CANL lines, to understand the overloading of the ESD protection diode on the CAN lines and capacitors in ...
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2answers
119 views

Grounding of IT equipment for office ESD protection

We've been having a lot of problems in my office with ESD. People touch cubicle frames and monitors shut off momentarily, painful shocks through laptops, etc. I'm worried about equipment getting ...
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5answers
6k views

Is it a bad idea to plug the other end of ESD strap to wall ground?

I have gone through this answer on Superuser, while it provides good information, I still have a specific question from electrical/electronics engineering point of view. Is it wrong and unsafe to ...
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1answer
127 views

ESD protection of battery operated device in metal case

I have a board design inside a metal case (video processing MCU), and it has one external USB port with ESD protection on all pins. It's battery powered and handheld. The exterior metal case is not ...
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1answer
141 views

Adding SMA conectors to a device whose metal casing is connected to earth ground through at a single point

We are iterating a device whose metal chassis is internally connected to an ESD guard ring that is connected to the PCB signal ground through a 0Ohm resistor in a single point close to the power ...
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1answer
164 views

ESD diode with zener configuration is equivalent to a circuit containing diode, transistor and zener diode, so how this could be equivalent

please tell me in the following link (https://www.onsemi.com/pub/Collateral/ESD9101-D.PDF), the ESD diode with zener configuration is equivalent to a circuit containing diode, transistor and zener ...
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2answers
974 views

Test pad's ESD protection

I design a module with onboard test-pads. I put ESD protections to all out-world connections like sockets etc. But I want to ask that; should I put ESD protections to test-pads and ISP socket inputs?...
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102 views

TVS diode selection for 3.3 V GPIO

Please refer to my project architecture in the image below: Power supply is isolated flyback smps type. GND is not connected to Earth or Neutral of 220 VAC. All parts of circuit are powered up with ...
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88 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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1answer
156 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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111 views

Soldering Iron and Electrostatic Bracelet Connection

I have a DIY soldering station and I want to ground the soldering iron and I also want to use a electrostatic bracelet connector for the soldering station. Can you please help me how to connect the ...
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1answer
142 views

ESD protection using capacitor

Will a capacitor actually help to lessen the effects of ESD? Because, with rise time of about 1 ns, the frequency of the ESD signal will be well above the self-resonance frequency of the capacitor and ...
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113 views

USB fail to pass ESD test even with TVS diode protection

I have read some articles about USB ESD protection and followed the suggestion to add TVS Diode Array USB6B1 in my design. However, my design is still failed to pass the ESD test and I don't know ...
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1answer
96 views

ESD Grounding Straps with No Chassis Ground

I've got water pump device that needs to pass ESD testing (IEC 61000-4-2, 8kV contact, 15kV air discharge). On this device (as circled in red), there are these four metal inlets. At 2kV with an ...
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1answer
174 views

DC floating ground and TVS Diodes for ESD

I want to provide ESD protection for a low voltage battery powered device and I do not understand what sort of net I should attach to the cathode side of the TVS diodes: I do not have a strong ...
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2answers
94 views

Preventing under-voltage from ESD strike to ground in floating circuit?

Consider a circuit like this... simulate this circuit – Schematic created using CircuitLab What happens to the voltage seen by the MCU between VCC and GND when this circuit takes a positive ...
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2answers
114 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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299 views

Any tricks for finding the path taken by small ESD sparks across a PCB?

A small ESD spark is able to find its way across my PCB at a relatively low voltage (low kV). It is not obvious which path the spark is taking and the sparks only jump when the board is sealed up ...
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69 views

Should I touch the metal surface of my ESD wristband?

Most ESD wristbands have a little metal surface (something like 20mm*15mm) and a part of plastic or some sort of cloth that goes around the arm. Is it enough to touch the non-metal part or should I ...
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2answers
505 views

The role of the series resistors for ESD protection

When one needs to protect a transistor or I/O pin of a processor, then a TVS diode can be placed between the connector and the transistor. Also a series resistor (R1) can be placed between the ...
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2answers
115 views

ESD problem on water tank?

We have a water level monitor attached to a water tank. The water monitor has an hydro-static (output 0-5V) water sensor that goes to the bottom of the the tank. (See figure) In most cases this works ...
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1answer
191 views

ESD protection for battery powered device

I have module that will be plugged into another device. The unit itself has no power and receives all power, and signaling from the mating devices. It has a 10 pos exposed connector (male pins) to the ...
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1answer
73 views

Connection of LAN8742A nRST pin causes failure when ESD strike

My circuit uses LAN8742A ethernet phy. The system has a metal case and gets 220V AC to power supply board. After converting 5V DC it goes to my board that has Ethernet and mcu. I screwed case and ...
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2answers
354 views

Protecting USB hub from ESD

I am working with a robot that uses USB (not by choice lol) in a very static-prone environment, and I'm having problems with ESD locking up my USB hub. I found an "Industrial" USB hub that claims it ...