Hot answers tagged

59

If your ground strap has a proper current limiting resistor, then you would be perfectly fine connecting it directly to ground. If your ground strap does not have a resistor, then it greatly increases your chances of dying if you connect it directly to ground. If you don't have a resistor in your ground strap, and you touch a live wire while wearing your ...


46

Your problem is the gate drive voltage. If you look at the datasheet for the STP16NF06, you'll see that the 0.08 Ω Rdson only applies for Vgs = 10 V, and you're driving it with only (a bit under) 5 V, so the resistance is much higher. Specifically, we can look at Figure 6 (Transfer Characteristics), which shows the behavior as Vgs varies. At Vgs = 4.75 V ...


33

Components are damaged by two or more of their pins being at a large enough potential difference. If the component has a conductive case, or pad, then that counts as a 'pin' too. It's possible to break them by trying to charge them up to a new potential through one sensitive pin, while the voltage of the other pins is held more or less constant through ...


32

The best way is to use an ESD strap, that is connected to earth via a 1MOhm resistor. This slowly but continuously discharges you without creating high currents. This way it does not hurt or damage anything. But I also want to mention one "trick", when you dont want to use special equipment like an ESD strap. Discharging at the earth connection of mains ...


31

Hopefully your parts are packaged in an ESD-dissipative tray or bag. Then when you set them down on your ESD mat in your lab, any charge that's built up on them can drain away through the packaging and the mat. They won't discharge quickly enough to damage the components because both the bag and the mat have substantial resistance (1 megohm to ground is ...


30

My go to method is my ghetto ESD-gun (a cheap electronic lighter) ala - Long neck lighter Split it open, strip the wires and zap away :) It should produce a few kilo volts.


28

Is static electricity really so dangerous? Yes. The conductive paths inside an IC are really small, so it doesn't take much energy through them to vaporize them.¹ There are millions of such paths inside the ICs of an Arduino, and it only takes damage to one of them to break the device. It is possible that you could get lucky and break some feature that you ...


27

You (and the some of the other answers) focus too much on the actual value of the resistance to ground; the fact is that the actual value is irrelevant regarding ESD. The ESD charge just needs a path. If that path is high-ohmic (few mega-ohms) it will only take slightly longer for the charge to find its way to ground. But it will still be a fraction of a ...


26

Best Practice Firstly (as a bit of a cop out) personally, in designs I always ground through a 0R resistor so that the decision can be changed. This goes for pretty much any shield (Ethernet, USB etc) The main problem that can arise is when the shield is grounded at either end, and the two ends don't agree on what 0V is. This can cause damage to either end, ...


25

You don't actually need to bond your ESD mat to earth. People do, but there is really no need. The idea is not really to earth yourself, but rather to create an equipotential region. You want to keep yourself, your mat, and any components at the same voltage - whether that be earth potential or the potential of your ESD mat. Set up an ESD mat on your desk (...


21

You are forgetting that these voltage sources are "ideal". So if your input is 20V directly from a supply, it will always be 20V. Throw a series resistor in there and you can see how it works. I used LTspice to model the circuit. R1 is the input resistance for some IC pin. I did a DC sweep from -10V to 10V with 1V increments. As you see, as I start to ...


19

The 1meg resistor is needed to safeguard the user from faults from other equipment connected to mains earth. Keep in mind that the wrist strap is a permanent connection to the electric system of the building. If another piece of equipment experiences a fault, there could be a big fault current through the mains earth wiring system. That means that, in ...


17

The point about the gate voltage is valid, but if the MOSFET is not heating up, I'm not sure that is the actual culprit here. 16 meters of 12 V LED strip driven at several amps is going to have a significant inductance at typical PWM frequencies. This causes voltage spikes at the drain every time the MOSFET turns off. These spikes are short in duration, but ...


16

It makes no difference where you connect the anti-static strap to your body. The reason is that your body is much lower resistance between any two points than the strap is. Also, most of the resistance between any two points on your skin is getting thru the skin at each point. You're just a bag of saltwater (electrically, anyway). The bag has a ...


16

You can use a ESD mat, which is directly connected to the electrical ground. Just place it under your electronics and wear the connected bracelet when you are working with them. Touching the mat when you arrive at your desk would also discharge the static charge without affecting your PC. Image source


15

should the alligator clip of the wrap always be grounded to the mains earth in a way? Yes, the alligator clip should be earthed. As should the work surface beneath the work piece. Is this type of wearing antistatic wrist strap aiming to protect the human from ESD shock or sensitive electronic circuits in general? It's meant to protect the electronics, ...


15

Yes, mosfets drains are sensitive to ESD. If you look at the Vds spec in the datasheet, it cannot be exceeded (for the IRF530, it's 100V), even for short amounts of time. ESD over-voltage conditions can reach thousands of volts. To prevent failure of the mosfet, install ESD protection. One way to do this would be to use a TVS diode that limits the voltage on ...


15

It's very tempting to casually say that the discharge is the return path, but it would be more correct to say that it is a path of resolution which dilutes an imbalance of charge created by some other means. We tend to think of current flow circuits but actually, circuits are just one particular behavior of charge. Another is the accumulation of charge (say, ...


14

Does this answer your question (emphasis added)? 9.3.2 Test method The test method shall be in accordance with EN 61000-4-2 [2]. For radio equipment and ancillary equipment the following requirements and evaluation of test results shall apply. The test severity level for contact discharge shall be 4 kV and for air discharge 8 kV. All other details, ...


13

The circuit protects against overvoltage and ESD subject to certain conditions. The main assumption is that Vd is "stiff" compared to the energy source on Vpin. This is usually true for Vd = power supply of say 1 A + capabilty amd Vpin is a typical signal source. If Vpin is eg a car battery all bets may be off as to how long it is before D3 is destroyed. . ...


13

Don't get hung up about connecting things 'to ground', that is, that brown stuff outside the door. What is important for you, your worktop, your tools, your components, is that they are all at the same voltage, before anything touches anything else. That's all you have to achieve, it doesn't matter how you achieve it. People who say it must be done this ...


13

My understanding is that ESD safety things are designed to bring everything that can touch a component to the same electrical potential energy That's when you're right. ground. And here's when you're wrong. There is no such thing as "universal ground". Not even Earth is. You just pick a point of a circuit and say "Hereby, by the power vested in me by ...


13

Grounding yourself is only part of mitigating ESD. You can still cause damaging discharges while properly grounded when the device you're working on is itself charged, when the tools you use (like a multimeter or screwdriver) are carrying a charge or when your workbench/parts bin is charged. Ideally you'd ground everything that can come into contact with ...


12

The answer to this question requires us to look at both the threat and the specifics of this circuit. ESD protection is not a one size fits all, unfortunately. The threat is IEC61000-4-2, 8kV contact. Note that the 15kV air discharge test is considered to be equivalent, as explained by this exremely useful note from On Semiconductor. Your amplifier ...


11

You may or may not be over thinking this, it depends on what your application is, and if you have to pass any regulatory inspections for a product. The general idea is to shunt the ESD to ground through the chassis and away from your electronics. This depends on if your enclosure is insulated or not. Another thing to keep in mind is you can also have RF ...


11

Electrically, it doesn't matter where it makes contact, with contact being the key word! I find however that it doesn't suit my workflow round either wrist or ankle. If worn on my wrist, the trailing wire interferes with stuff on my bench. If worn on my ankle, it's a long way down to attach and detach, and being out of sight, it's easy to be working for a ...


11

Even if I doesn't take such precaution, chips behave as expected. Is that normal? Yes, ESD is an unpredictable event, and you can't see it (most of the time, sometimes you can see damage on IC's). Sometimes it only damages a trace partially and it could take months or years for a chip to fail, sometimes the effect is immediate and the circuit ceases to ...


11

I also live in the Netherlands and these contacts are indeed quite common. However, I assume somewhere in your house you also have the ground version (see picture below), which includes ground. I'm not a technician, neither a professional electronics guy, however, I suggest you connect your ESD mat to a version like above. Another reason to do this, is that ...


10

Either is ok, The idea of an ESD band is to slowly remove charge from your body and equipment you contact. If there was no resistance, there would be two problems: Danger of electrocution if you touch a high voltage with respect to the ESD strap ground. You could have rapid voltage shifts causing ESD like scenarios. If we look at the 8kV Human body model (...


10

Here is an excerpt from chapter 7 of Note: copying images because PDF files are protected and text cannot be copied. BTW: here you will find the entire book freely: OP AMP APPLICATIONS.


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