Quick Circuit Tips #1 - ESD Protection - KiCad

Quick Circuit Tips #1 - ESD Protection - KiCad
This video discusses a few of the common methods to protect a PCB and components from dangerous ESD event.
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[@suncrafterspielt9479]

I would love to see some more design reviews

[@MicroTypeEngineering]

I'm thinking the next video is going to be a review. I don't get many submissions to do them on anymore :/

[@Ray-ej3jb]

Hi microtype Eng. Some feedback. First off I love your videos. Even though you seem to doubt what you do and your content, you have found a niche area that nobody else does - proper design vids, background rules of thumb stuff that just works and EXPLANATIONS of why you decided on a component verses another this is invaluable!!. The amount of hands-on practical experience knowledge your give us is superb. I know theory but have limited experience constructing things that work in the real world - you help fill this gap. Please just keep banging out LOTS of design videos, don't worry too much about ' if we might find them interesting' we might in the future when the info is relevant to our project, and also don't worry too much about the length we want good information. The only criticism I have is your verbal delivery when your trying to talk 'proper' to camera - it is very monotone and Canadian. When you talk to us ad lib and making it up as you go along (like talking to your mates down the pub) it is MUCH easier and enjoyable to listen to. Have you considered a forum like EEVBLOG has - it's another link from KZbin and its search algorithm. Content suggestion - DC powerline filtering how and when to use inductors perhaps. - I am working on electronics in an automotive based environment (12Vdc boat) and cant find suitable info on filtering, voltage regulators etc.

[@MicroTypeEngineering]

Hey! Thanks a lot for the comments. Much appreciated. Yes, I fully understand your critisism and I knew it was an issue. I will work on my summoning my inner "Dave!"

[@Ray-ej3jb]

@@MicroTypeEngineering LOL sweet geesus NOOO dont work on summoning your 'inner Dave' you idiot, it takes too long now stemming the blood coming from my ears (luv ya Dave mate). Apologies, criticism should have have had apostrophes around it, I re-read my post and comes over harshly without them and not what I meant. My comments about Eevblog was directed towards the forum where we might interact and ask question and you could get revenue from some ads perhaps.

[@shoppingoneclick2044]

I am also looking for DC power line filtering and use of inductor ( filters like LC filter + pi filter). Mine case is 5V supply for AVR microcontroller.

[@helmuthschultes9243]

Had an instance of a Automotive module that failed by destroying the MPU on ESD testing. All usual protection applied to the PCB, but someone in layout passed a trace with direct path to the MPU across a incoming trace and placed a through hole a minimum distance right beside the track to a line direct to input connector but infront of ESD protection. On ESD event the track at HT voltage flashed into the through hole and thus direct to the MPU pin on that track and blew the chip. All other 30 odd connections to the world with ESD protection could not help with that layout mistake. Increasing the separation between input track and the through hole....no more ESD fail. Sadly there was great issue to not even pass that track that way across the board at input lines. It was that input or anyone of many others. But not putting the through hole at such minimal spacing was easily done.

[@MicroTypeEngineering]

Well put! I focused on the schematic side here mostly, but yeah, layout can easily have just as big of an impact on ESD and transient protection

[@frankbose544]

Man I love these videos and believe me wen I say your efforts you put in these videos are much appreciated by a hobbiest like me thank you

[@MicroTypeEngineering]

Glad you enjoy it!

[@kassutronics]

Great video and channel! One comment on the Schottky diode to 5V: for overvoltage events it is important that the power rail can actually deal with the injected current. Taking your example, if 15V is applied externally, the 220 Ohm resistor will pass something like ~ 45 mA to the 5V rail. If the MCU (or other circuits on the same rail) draws at least that much current it will be fine, but if not the 5V rail will probably go up in voltage and fry the MCU by overvoltage. One way to deal with this is to additionally have a TVS or Zener diode on the 5V rail to clamp it to within the MCU maximum voltage rating. For ESD events this is probably less of an issue, if there is some bulk capacitance on the 5V rail to absorb the current spike.

[@MicroTypeEngineering]

Yep, spot on. There's certainly a lot of different routes you can go to protect circuits, just depends how much you need!

[@BusyElectrons]

Thanks for posting this. I'd never heard of the Bourns TBU series.

[@tuloca011]

Great video, hope to see more of this series!

[@gn6034]

Love your content just want MORE. Please do more designs explaining your justification for components used and your thought/reasons why you go in a certain direction. For a novice just reading a datasheet is not the full story. Suggestion, why don't you buy random breakout boards from eBay, adafruit, sparkfun etc and create a real world projects around them incorporating the above notes.

[@MicroTypeEngineering]

Would I remake the breakout boards on a custom PCB, or just use them as is?

[@dd884e5d8a]

This is exactly what I wanted to learn. Thank you for publishing the video

[@oseyedian]

I cannot thank you enough!

[@frankgrudge8823]

Vids on circuit building considerations are great thanks man

[@SaiKiran208]

Keep up the work man, i am getting to know these imp things

[@toalan]

Good practical knowledge, subbed.

[@10e999]

Quick Circuit Tips Idea: - Good practice to minimize EMC and EMI problems. Great video, as always !

[@MicroTypeEngineering]

Noted! Thanks, glad you enjoyed!

[@wi_zeus6798]

Thanks for the video. I'd like to add some thoughts: there are also Bi-directional TVS diodes available. It may be better to use one instead of the dual schottky diodes since they are designed to protect against static discharge. These devices allow current to flow in both directions, depending on the polarity of the ESD event (equivalent to the dual schottkys). Also, there are varistors, which can be used to protect against ESD. Personally, I have never heard about these more intelligent protection devices, very interesting! :)

[@MicroTypeEngineering]

Yeah, I was going to mention bidirectional TVS's. Actually, they are quite misunderstood, and used in the manner that you mentioned, which isn't actually correct. Since they are essentially just a zener diode reverse biased, you only need one, not two. The only reason for bidirectional is for dealing with an AC signal, one that goes from + to -. A great example of that is an RS485 line, that can be +-12V. For a standard 0/5V signal, there is absolutely no need for a bidirectional TVS, a standard Unidirectional works fine. See: www.onsemi.com/pub/Collateral/AND8424-D.PDF Yep, varistors can be great!

[@wi_zeus6798]

@@MicroTypeEngineering I think that I wasn't very good with my wording there, I didn't want to say that you need two Bi-directional TVS diodes to replace the dual schottkys ;) Yes one from signal to protect to GND will be enough. Please keep up this series, it's really interesting Edit: after reading your answer properly, my statement in this comment doesn't really make sense either. A uni-directional tvs diode is indeed better for this use case. Man, this is getting better and better :D Awesome to get new insights!

[@carlosgarcialalicata]

@@MicroTypeEngineering I'm just realising that. Why do they add bidirectional to UBS then?

[@Excalibur32]

Another extremely useful video, thank you!

[@MicroTypeEngineering]

Glad you liked it!

[@IanJohnstonblog]

Just found your channel. The content is great, and you’re a good teacher. Well paced, and thorough explanations. Thanks!!

[@MicroTypeEngineering]

Thanks and welcome!

[@imboredsauce]

0:00 seconds in and already liked and commented. Please keep these going!

[@MicroTypeEngineering]

Hah, glad you enjoyed!

[@francescocamobreco6425]

Great video thanks :)

[@electromatic2014]

I used the TBU for the same exact application as you did!, pretty good video about ESD, very much what I also do :)

[@MicroTypeEngineering]

Good stuff!

[@Asyss_Complex]

This was very informative! I'm glad you mentioned the series resistors. They are simple yet a very effective solution. In my latest project I'm using a bi-directional TVS diode, like you said they're extremely fast and they usually fail by creating a short. From what I've been reading they're commonly used in the automotive industry. Another ESD protection device worth mentioning is the MOV, although I believe they are preferred for high energy applications, mostly AC mains.

[@MicroTypeEngineering]

Absolutely!

[@AhmadAsmndr]

Thank you very helpfull

[@davidmaruska1641]

I would love to see a topic review on Fab notes to PCB fab house. Discuss the IPC standards and which are called for in pcb fabrication.

[@MicroTypeEngineering]

Yeah, honestly, I've been planning a video like that, with general PCB design rules for like a year now.. I'll get to it some day!

[@PszemoI]

Good video, thanks. How do you select the parameters of the series resistors? I am trying to protect 4x8 matrix keyboard, so the size of the resistor is important to me - not sure what is the minimal voltage/power to pick. Also, less resistance means more current flowing in impulse to the shunt diode, but also means less power dissipates in the resistor. So resistance might play a role in tandem with voltage and power.

[@electronicrepairservice1705]

ESD is a very interesting topic. I have a power supply board & control board that I believe were victims of ESD from a lightning strike (no board damage). After I get the PSB working again, I'd like to add ESD protection to protect the controller IC (MCU) on the control board it powers. To do something like that would the TVS diode be installed inline near the VCC input to the controller IC?

[@OrbitalCookie]

Thanks, awesome info. How one would go about choosing the power rating of a resistor in this application?

[@MicroTypeEngineering]

Great question! So actually the power rating of the resistor is usually not important. Since resistors fail from prolonged power dissipation due to heat, normal ESD events are too short to matter. You can buy "pulse withstanding" resistors that have a quantified chart on the power and time they can handle. It'll shock you to see how much power a 0402/0603 resistor can handle for a short amount of time.

[@belfalas40]

I really enjoy these videos, so much detail to consider in a good design, always learning. By the way Is that what all those R/Cs are for on desktop CPU packages?

[@MicroTypeEngineering]

Glad you like them! They're used for various things. The huge amount of caps right near the CPU die are going to be mainly for decoupling/bypass.

[@belfalas40]

@@MicroTypeEngineering Yes, I'd always assumed that might be the case but never investigated - it's not like full datasheets are generally available! Another possiblity is series termination for DDR, etc. but in watching your video I wondered whether additional external ESD mitigation might be a reason. I guess it would be much cheaper to just reserve a larger chunk of silicon in the IO sections for this though!

[@arlenalem]

Very useful video, thanks for sharing :), If a have digital signal that is expected to have 3.3V max and that I/O can stand a 3.6V as maximum, I should choose a ESD diode parameter Vrwm = 3.6V? or it could be bigger? , let's say Vrwm=4V or 5V?. BTW diodes with Vrwm = 3.6V are expensives

[@danhellgren5671]

Great video. This is what differs between good and great engineers. Do you have any practical experience of the necessary size of R-C ( 0402, 0603 etc) ?

[@MicroTypeEngineering]

Glad you enjoyed! Typically for RC's in digital circuits in general, you want to make sure that the max frequency of the signal is going to be below the 3dB cutoff frequency of the filter. This is to make sure you don't have any interference with the filter in your signal. It of course depends on the type of signal, as the 3dB might be too much attenuation, and you need to have a "less effective" filter. As for physical size of the components, for standard ESD protection it normally doesn't matter a whole lot. It really would depend on how strong the events are expected, and if you have a specific standard you are designing towards. (Note: look into surge withstanding resistors, check the datasheets and see what they can withstand! Super neat)

[@WagonLoads]

8:20 How about going from left to right on your diagram. Double this circuit from left to right, then make the left pair TVS diodes and right pair Schottky? That way the pair on right absorb the main force, then the pair on left take care of the remaining surge? Can opto isolators block input surges?

[@eons_of_ions8651]

Would it be possible for a video on what it takes to start your own design firm? How did you find your first few clients to get going?

[@BurntTransistor]

Thanks for the video. Would there be any reason to use both Schottky clamp diodes AND a TVS diode in parallel? Also, what's your recommended setup for digital outputs?

[@MicroTypeEngineering]

Sure, if you use them both, the TVS diodes will conduct faster, but since the Schottky's conduct at a lower voltage, if there is a sustained event, they will take the brunt of it, potentially saving the TVS' from burning up. Digital outputs can be much of the same, but making sure to handle the potential for short circuit events. Remember, ESD doesn't care if a pin is set as an input or output, it'll destroy things all the same!

[@BurntTransistor]

@@MicroTypeEngineering Thanks for the reply. I think there could be merit in going for a slightly higher voltage TVS (say, 60V) and let the Schottky clamps take care of any sustained over-voltage up to that value. This way we can avoid the series resistor before the TVS as it could create a challenge for precision voltage divider setups, where that series resistor, and TVS leakage, would need compensation in software. Of course we'd still have a series resistor post-TVS for the Schottky clamp/low-pass filter.

[@TomLeg]

A question concerning resistors and capacitors for analog audio synthesizer circuits (eurorack). The RC time constant determines timings and resistor ratios determine op-amp amplification factors. But what are the best values to use? Too small an R will waste current. Too large will, I suspect, increase the amount of noise. But how much is too much?

[@matthollandsf]

I recommend checking out "small signal audio" by Doug self. It's geared towards audio circuits not synth circuit but you can use the same principles. In general I'd think Johnson noise is less of an issue in synth circuit.

[@carlosgarcialalicata]

Can you use the same for a power line? For example, in case there are inductance spikes

[@radudum1]

Please , if you can ,make an explicit video for high power circuit board (circuit schematic, pcb, device selection, parts selection,etc)! You will help me so much!Thanks and keep with the good work!

[@MicroTypeEngineering]

Have you watched my "High Power Circuit Board Design" series at the beginning of the channel?

[@radudum1]

@@MicroTypeEngineering Yes, but those videos are fast forward and i need more information about the design,pcb routing, how you choose width trace, how you choose components, maybe a 4 layer design.A more explicit tutorial would help me better.

[@MicroTypeEngineering]

Makes total sense. Any idea's on an interesting design/project for something like that?

[@radudum1]

@@MicroTypeEngineering For example i will like to see your ideea about how to make a circuit design (circuit schematic, parts to use and why you choose those parts, protection circuits, safety measures,maybe a pcb layout)for power a UV-C lamp using a 5V power supply and ESP-32 to control that UV lamp (start/stop) via bluetooth connection.I must add the fact,but i think you already know, that UV-C lamps are used for sanitation ,sterilization and the voltage needed for them to work is main power supply voltage.

[@sanjaybatra6593]

tvs diode can be used as input filter ?

[@111chicane]

I'm confused by those Schottky diodes being used as an ESD protection. Most are usually rated for no more than 30V reverse voltage in smaller packages. I understand that the surge will get clamped through the open diode and not affect the other one in reverse, but is that safe enough? Also, a negative surge will be sent to the positive rail and from there it still has to reach GND through something else, that will also get zapped with a few kilovolts. I'm not convinced that's a good design for ESD protection. I would rather go with TVS to GND or TSS to GND. You may want to look at TSS (Thyristor Surge Suppressor) if aiming high reliability. They also don't need that resistor in series of the I/O, as they can withstand a lot higher current than a TVS.

[@alexstone691]

Im interested when should you add esd protection, should you add esd protection on all headers for example

[@MicroTypeEngineering]

Ahh, you know what, I didn't mention that did I..? Oh well.. Yeah, so ideally, any "thing" that see's the outside world (buttons/switches/connectors/plugs/screens/etc.) should be protected from ESD. Of course due to BOM costs/size/etc. that may not always be possible. So then it's just a matter of nailing down the most important and/or vulnerable components, and protecting them.

[@WagonLoads]

Can ESD be conducted through 3D plastic? Lets say all of your buttons light up an LED. The LEDs are ported through one side of 3D plastic (light tubes) with photo transistors on the other end. Would the plastic conduct the ESD to the other side?

[@davidgrey943]

I am setting up a test bench I would like to know if I need to ground my test bench equipment to your ESD mat so that they all at the same potential. And the risk between your scope and switch-mode power supply under test when fed from an isolating transformer to protect your scope. I hope you can understand the question I am trying to ask it will probably require a two answer.

[@MicroTypeEngineering]

Uh, standard practice is to earth ground all ESD mats, regardless of where else power is coming from to you DUT.

[@davidgrey943]

@@MicroTypeEngineering Thanks for your reply I am enjoying the content of your channel and learning a whole heap of stuff. I am a new user of Ki-Cad and have learnt a lot of tips and tricks I did not know for the software. Thank you for the hard work you have put in producing the various topics on your channel.

[@robottalks7312]

How do we design a TTL to RS485 converter with proper protection

[@prasaddivate3753]

ESD Capacitor calculation formula ?