How to Protect Your Devices Against Reverse Polarity Using Ideal Diodes

[@Afrotechmods]

Be very careful with the LM74610. Back in 2016 when it launched I tried making a video about it. It basically didn't work in half the situations I put it through. I concluded that there was fundamentally a problem with the silicon. Try rectifying AC using it and watch what happens at different frequencies and load currents. The LTC43xx family works great though. I am guessing that there is a good reason why there are not more non-ground referenced ICs out there. Too good to be true. Also please be careful posting ChatGPT output. Unless I am mistaken LM74612 and LM74600 do not actually exist and they were just hallucinations.

[@VandalIO]

Miss your videos mate !

[@mihajlopetkovic2003]

I still remember your video with p-channel MOSFET. 👍🏻

[@VandalIO]

@@mihajlopetkovic2003 me too !!! I remember it as if I watched it yesterday

[@justanothercomment416]

People need to understand these systems are simply complex search engines. They will spit out anything which is the median consensus of its training data. It has no correlation with correctness nor accuracy. If you want the best answer it will never come from these types of systems.

[@sc0or]

@@justanothercomment416search engines do not hallucinate. You see an original text in search results. Search engines could manipulate a relevance rate to help their client to sell more goods though on the other hand. I tried to use gpt as a search engine, and realized that I cannot trust it. It can represent someone’s answer on “reddit” and ignore a fact that there were 10 other comments proved the author was wrong. But it’s good in making conclusions. As many other neural networks (because nn were always good in highlighting existing patterns)

[@newburypi]

I've used ideal diodes in a battery "hot swap" situation. When battery 1 was getting low, I could plug in battery 2, then unplug battery 1. Battery 1 could then be recharged. This way, the power to the equipment would not be interrupted when replacing batteries.

[@AndreasSpiess]

Good idea!

[@daw7563]

One thing: The most common failure mode of a diode is that it shorts, they rarely go open so a diode should not be considered a fuse, as the video suggests @4:20 A reveresed diode in series with a fuse (reversed over the load, fuse in series) is an optimal protection.

[@TheTemporalAnomaly]

It was meant as a joke, you know diode turns into a fuse. He never seriously suggested you would use it that way. We should not be in the electronics field if we would entertain the idea of using a diode in place of a fuse, unless in jest.

[@AndreasSpiess]

Indeed, i thought it was a joke (obviously not a good one because it has to be explained). But one other commenter wrote that he uses diodes as a fuse...

[@daw7563]

Yeah, I did not catch it as a joke, but perhaps it was obvious for others. 🙂 But if it can be misunderstood it is a bad joke, it could ruin someones projects while trying to learn electronics and leave the video with the wrong "fact".

[@MadScientist267]

​@@daw7563The people that don't bother to understand first and "just do" don't get my sympathy.

[@LiviuGelea]

"It is rated to 40 Chinese Amps" 😂

[@3d8d]

You got the right point about this. Chinisium ratings are different from ours.

[@letouioui6621]

@@spotonnls3538unless it’s a fuse. In which case it’s 400 of our amps

[@benjaminpauza159]

What is the conversion for Chinese Amps to Amperes?

[@LiviuGelea]

@@benjaminpauza159 Depends on whether it's a fuse or not. Fuses are X2, all others are X0.5

[@AKG58Z]

​@@LiviuGeleawhat kind of sense is that

[@dennyfox3139]

Welcome back! I hope you had a great holiday! This was a very interesting video...

[@AndreasSpiess]

Thank you! Yes, it was a good summer. Lots of travelling and small projects around the house (that are not worth sharing, but still had to be done).

[@kepamurray1845]

I'm so glad you put this out. I have been toying with this exact problem for a couple of weeks. Thanks, I am dealing with this because of a fantastic smoke release episode that resulted in the waste of a week's work.

[@AndreasSpiess]

I am glad the video was helpful!

[@Steve_Coates]

A friend has recently replaced the beefy schotky diodes on all his solar panels with ideal diodes. He claims a 2-3% increase in output but I suspect the main benefit is that the ideal diodes don't melt the plastic box the original diodes were mounted in.

[@AndreasSpiess]

Interesting idea! If he has a lot of shadow on one panel, they could get hot. But I also doubt the big efficiency gain.

[@Steve_Coates]

​@@AndreasSpiessSo do I although if it makes him happy that the work and expense involved were justified I'm not going to argue the point.

[@bennylloyd-willner9667]

My worst (most costly) "reverse current incident" happened in the mid-80s. I was examining a German Z80 computer accessory card, a pretty expensive A/D converter. I put on the power, and it burst into a short flame and then black smoke. Since it was black smoke, it wasn't repairable (you need grey smoke for that as you all know😁) It turned out I should've checked the power connector, the brilliant German engineers who made the card, decided that black should be the positive connector and red the negative, just for this accessory card while all other components in the system were the standard red for positive 🤦‍♂😂

[@xxportalxx.]

Yep, can never trust the colors, there are no true standards, just conventions.

[@jamesphillips2285]

@@xxportalxx. One North American truck (highway tractor) brand (forget which one) enforces that by making every wire yellow. Not sure if they save any money during manufacturing, or if it is to prevent easy wire tracing.

[@xxportalxx.]

@jamesphillips2285 I was just working on a pump controller yesterday, had a wiring diagram in the manual, but my controller had a slightly different revision of one of the boards, they swapped the wire colors between revisions!

[@AndreasSpiess]

Nice story. Thank you! I recently had a new device with black as positive (I think it was for a car). Very misleading! I thought at least red and black are quite common these days,

[@ve2zzz]

Not only Germans, British paging systems use a RED ground.

[@SkyhawkSteve]

I used to design electronics for earthmoving equipment, and reverse battery protection was essential for any piece of electronics. For small sensors, a diode was usually sufficient. For larger items like ECUs, the solution tended to be similar to these devices that controlled series mosfets. The electronics also had to pass a variety of electrical transients tests, EMC tests, etc., so that made things a bit more interesting. 😄 Thanks for the video!

[@AndreasSpiess]

Indeed, adding transitions makes things more complex!

[@OldCurmudgeon3DP]

Informative video. The transitional Morse beeps made me think my BT battery was low.

[@AndreasSpiess]

I never had a BT device capable of doing morse. Mine usually talks chinese. Morse would be better understandable ;-)

[@mcconkeyb]

Nice, I liked the Morse code section delimiters, spelling out the word diode. When it comes to polarity protection, I normally go in a different direction. My go to design is to not put the main power through the protection diode but to put it through a resetable fuse, then I put a Schottky diode in the reverse direction across the power input but behind the resettable fuse. So if the user applies reverse power the diode acts as a short circuit and causes the fuse to open protecting all the circuitry including the protection diode. Once the polarity has been fixed then the fuse resets and operation can continue normally. I think this is a better alternative for 2 reasons, but it has 1 drawback. Its better because it forces the designer to include a fused input which provides protection for both polarities of incoming power, something that all equipment should have. Secondly it does not dissipate any power when the polarity is correct. The 1 drawback is that your internal circuit is subjected to a reverse voltage equivalent to the forward voltage of the protection diode. So if you are designing very sensitive circuitry further internal protection might be required.

[@leocurious9919]

I really did not like the super loud beeps.

[@LanceThumping]

@@leocurious9919 I also really hated getting really loud beeps directly injected into my left ear.

[@AndreasSpiess]

A good idea for low power devices. I assume it has a low voltage loss. It is sometimes called "Crowbar" because you shorten the power cables.

[@mcconkeyb]

@@AndreasSpiess Some call it a crowbar, but it is not quite right to call it that. It also works for any level of power as long as you select the correct fuse. 🙂

[@guytech7310]

Even better use a TVS diode which adds over voltage & surge protection. Cheap & easy!

[@barnowl6807]

Some years ago I was looking at using the AD 8013 log detector. At the time this was an expensive part. The circuit included an op amp and a voltage regulator powered by a 9 V battery. The PC board layout and circuit worked great. The 9 V battery was connected with the typical battery connector taken from a new package o 5 connectors with wires bought from Radio Shack. After installing the board in a shielded metal box a new 9 V connector was used from the battery in it's holder to the board through a switch. When the switch was turned on smoke was released from every IC on the board. Turns out the red - black wire polarity was switched on ONE connector in the package.

[@AndreasSpiess]

That with the colors was bad luck! But using a 9V battery without reverse voltage protection is not a good design. These bricks can easily be reversed because they have absolutely no protection. The same thing can happen today with JST battery connectors. Because there is no standard, each manufacturer choses its setup. If the PCB and the battery are the same, you are lucky. Otherwise not. I also learned it the hard way (similar to you).

[@segwaydave]

Did I just hear DIODE in morse code over the span of the video? Nice video!

[@Sekir80]

Indeed you did!

[@AndreasSpiess]

Congratulations!

[@kmkessler]

Even I can follow Morse Code a 0.1 WPM

[@JimFelich]

I learned something new today. Thank you.

[@AndreasSpiess]

Thank you! Up till recently, I also did not know that these ICs exist...

[@herrgerd1684]

​@@AndreasSpiess that's why I love browsing AliExpress 😁

[@4bSix86f61]

@@AndreasSpiess 9:50 Looks like the most promising part for today. 5A/28V

[@cjhtas]

Went to Antarctica with a mate who was installing a very clever gadget to run a camera in a box to photograph penguins. Sealed in a box, allowance for day/night length, windscreen wipers for blizzards, shutter etc etc. The guy who built it assumed it would have power leads correctly connected. Didn't work. You know why. Months of work wasted for want of a simple diode.

[@AndreasSpiess]

That is a very sad story! Thank you for sharing. Engineers sometimes are too focused on the main reason and forget the obvious.

[@siberx4]

It's also worth noting that while schottky diodes have low forward voltage drop, they do have more reverse leakage current (anywhere from 100-1000 microamps is typical for many parts) compared to standard silicon diodes (usually single-digit microamps or less). In most cases this is small enough to not matter too much, but it can result in "float" voltages higher than you expect on the anode side if there's no circuitry there drawing the leakage down.

[@AndreasSpiess]

Thanks for the clarification! I did not know.

[@NicksStuff]

There's another very simple solution (used very often in old electronic games using batteries for which the voltage drop would be unacceptable): place a reverse biase diode between ground and VCC and a fuse between VCC and the diode branch. In normal operation, nothing happens; if you inverse polarity, the diode will conduct, short VCC and ground and the fuse (which is before the diode) will pop.

[@AndreasSpiess]

I agree. Some commenters named it "crowbar" method. But you have to have a replacement fuse handy...

[@LORRY2000]

I like your reverse engineering approach with ChatGPT, Andreas. The information content of your contribution is worth its weight in gold. Thank you and 73.

[@AndreasSpiess]

Thank you for your kind words! Indeed, ChatGPT is sometimes helpful. Particular with "fuzzy" questions.

[@olipito]

I would be really interested in seeing the Fulll Bridge Rectifier build! Maybe as a short add on to this video?

[@johansvideor]

You can use an LT4320 and four Mosfets.

[@AndreasSpiess]

You know who could do this much better than I can ;-)

[@srenkoch6127]

@@AndreasSpiess Yep with more sparks :-)

[@johanneswerner1140]

That was fun! I taught myself to morse, but I forgot too much.... I had to resort to paper notes and then looking it up. The video was interesting, didn't know about ideal parts actually existing. Next we'll try for the perfectly spherical race horse in s vacuum on a frictionless surface.

[@AndreasSpiess]

That is what I feared! That people will ask for a "Perpetuum mobile" because an ideal diode seems to exist ;-)

[@johanneswerner1140]

@@AndreasSpiess well said! And if Swiss ingenuity cannot pull that off, I fear the laws of thermodynamics still hold.

[@KlemenZhivko]

Perfect, you explain it as it should be. You are real gem Mr. with swiss accent.

[@AndreasSpiess]

Thank you!

[@icebluscorpion]

I don't get the stupid people complaining about the beeping... I had also Headphones on. Those people should be less of a wimp and more like a electronic engineer. Seriously the youth from nowadays should grow some balls and I solved the secret it is Morse code At 0:59 .. _ = D At 1:38 .. = I At 8:00 _ _ _ = O At 9:20 .. _ = D At 10:41 . = E The secret message is: DIODE Great job pal 👍 keep it up! 💪

[@AndreasSpiess]

Congratulations!

[@deangreenhough3479]

Interesting work Andreas. Welcome back from your holidays🏴󠁧󠁢󠁥󠁮󠁧󠁿😁

[@AndreasSpiess]

Thank you! Just was another week off (10th wedding anniversary). This is the reason for my late replay.

[@PexiTheBuilder]

Best reverse polarity experience was with H-bridge in balancing bot. Once realize damage was done, went all in with 2S Li-Ion and let it burn as much as possible. Core of chip went red hot in few seconds and gave nice thick smoke.

[@AndreasSpiess]

Nice story! Indeed, these Li-Ion batteries can do a lot of harm!

[@marcfruchtman9473]

Thanks for the very interesting video. Good to see how increasing current substantially increases the voltage drop across the diode... I had been thinking about this architecture a lot lately... so glad you brought it up!

[@AndreasSpiess]

Indeed, this is an old topic. However, I did not find a lot of videos about it...

[@glasslinger]

Nice video on a rarely covered subject. I had tried the "FET pair" version (no IC type) and had so many fails I gave up on the idea and got a big box of heat sinks.

[@AndreasSpiess]

I saw that the topic was not well covered. That was the reason I made this video...

[@DumahBrazorf]

I not use headphones but i'm sure headphone users hate diodes.

[@4bSix86f61]

Rectified audio rip

[@laserhobbyist9751]

You always do such great work, but calling a failed diode reverse biased across a voltage source a fuse is misleading as it does not act as a fuse. It may fail like a fuse does by internally opening, but has no fuse action to the protected circuit or equipment, it shunts to ground.

[@AndreasSpiess]

It was ment as a joke (obviously a bad one since it needs an explanation).

[@SteveBrace]

Secret message received and understood... ->|- 😄

[@AndreasSpiess]

Congratulations!

[@johnwest7993]

The first time I heard your accent I thought you were Dutch. But I didn't actually know what either accent sounded like so it was just a guess. :) "Energy does not disappear." Mine does.

[@RuddODragonFear]

He does explain very early that he is the guy with the SWISS accent.

[@AndreasSpiess]

Indeed, Dutch and Swiss German are a sort of "dialect" of German. However, I do not understand Dutch (and they usually do not understand Swiss German).

[@ve2zzz]

Thanks for the info... I knew about primitive ideal diode using a P-CH MOSFET, 10V zener diode and a resistor but these IC's use N-Channel MOSFETs which provide a much wider choice of silicons. BTW, the P-Ch reverse polarity protection connects the Source to the INPUT, Drain to the OUTPUT and the Gate is connected to negative rail via a 1k resistor. 10V Zener between G and S protect Gate from over voltage. A 10nF cap. may be. inserted between G and S in RF circuitry. Thank you.

[@AndreasSpiess]

Thanks for the info! Did I make a mistake?

[@LawpickingLocksmith]

Thanks Andreas. You are the first to tell me. As a realist I hate the name given to this product. Just like WEP encryption these diodes have their place. Ideal is not what I would call them. They should be called electronic diodes or controlled diodes. I have come across low loss schottky diodes with amazing low losses.

[@AndreasSpiess]

I agree that they are not ideal ( and many data sheets do not use this expression). But it is a handy and short name...

[@LawpickingLocksmith]

@@AndreasSpiess Sometimes they create a box where you plug in some ethernet cables. Because the word hub is already taken they also find that abusing upper side band finds rejection so they use an entire now and never never never ever used word: Here we are, call it SWITCH!!

[@KnowledgePerformance7]

Most smoke was accidentally discharging 10kV directly into an ADC chip running at 3.3V. Made a surprisingly large hole in the package, almost the size of the entire die.

[@Sekir80]

That sounds just great! :D

[@AndreasSpiess]

I hope it was not an expensive precision ADC ;-) Thanks for sharing!

[@ifell3]

40 Chinese amps 😅 Great video as always sir

[@AndreasSpiess]

Thanks! 😃

[@borisjevic6338]

Loved your morse code secret... Previously known as a "rectifier" 😉 it starts with a 'D' & ends aith an 'E'

[@AndreasSpiess]

Congratulations!

[@de-bodgery]

Thanks..I knew of these implementations of mosfets, but never really spent any time thinking of how I'd use them instead of schottky's.

[@AndreasSpiess]

You are welcome!

[@GapRecordingsNamibia]

In the old days, we made "diodes" like this using a P channel mosfet a resistor and a zener diode..... Pretty simple, we rated the mosfet for the current and to a lesser extent the voltage and the zener diode for the gate voltage of the mosfet.... The resistor was something rediculosly high to make sure that there was some current flowing but never enough that the zener diode would ever burn out but that the gate would never see more than the 5, 10, or 20V limit it had....

[@AndreasSpiess]

Still works ok if you can spare the current across the zener diode and the resistor.

[@Validole]

My pro lem with ideal diodes is that I'm usually looking for them in situations where battery life is critical. And they invariably have more quiescent draw than I would lose on the diode. The old "series mosfet with gate tied to GND" works for single-supply situations with low load-side capacitance, but fail in situations where multiple sources are available. To be fair, I usually measure current in micro amps, not milliamps...

[@AndreasSpiess]

Thank you for sharing your experience!

[@jamesmichener7526]

One use case you failed to mention was for power supply ORing (okay the solar charger is kinda the case) To power my network equipment with a "UPS", I have two power supplies, one fed by the mains, the other is powered from a battery. Two Diodes (ideal) OR the voltage to feed the load, (all of my networking stuff). In the past I used a 95SQ015, an over doped Schottky diode, but these devices have terrible reverse leakage current at low offset voltages, the leakage current is very temperature sensitive. This required >350mv offset voltage between supplies. Enter the world of ideal diodes... they work perfect even down to 60mv offset between supplies. Since, in my case I was ORing 12v power supplies, using an ideal diode that requires > 9 volts and saved from cash. -.. .. --- -.. .

[@AndreasSpiess]

Indeed, I did not name it "ORing" because I did not like the name (even if it is technically correct). It took me a while to understand its meaning. Your scnario is a very good example. And others also mentioned that Schottky diodes are not ideal for that purpose because of the high reverse current. I di not know that fact.

[@jamesmichener7526]

@@AndreasSpiess The 95SQ015 is a special Schottky diode, with a lower threshold voltage, at the expense of a high leakage current with a slight reverse bias, and is often used for reverse voltage protection for Vcc < 15 volts. I thought "ORing" diodes was a common term (it is in the US)

[@AndreasSpiess]

@@jamesmichener7526 As a non-native speaker, I definitely sometimes behave strangely. I am influenced by German and occasionally French words or concepts...

[@jamesmichener7526]

@@AndreasSpiess Fear not... in the US a two transistor NPN/PNP amplifier, is often called a "69" amplifier... a term that I doubt made it to the EU

[@PatrickFelstead]

I found this useful and interesting. Definitely a fresh idea around power supplies 😊

[@AndreasSpiess]

Thanks!

[@avejst]

Great find Good introduction as always Thanks for sharing your expirences with all of us 🙂

[@AndreasSpiess]

You are welcome!

[@flack3]

Great video! Got yourself a new subscriber, thank you from Canada!

[@AndreasSpiess]

Welcome aboard the channel!

[@ShinesMonkey1]

Sounds like the LM73100 would be perfect for small voltage/current Arduino or Pi pico projects. Thanks for the info!

[@AndreasSpiess]

I think so, too.

[@graemebrowne1463]

Loved the morse ... always interesting and informative.

[@henkoegema6390]

So did I. 😄 73, de PA2HO

[@Sekir80]

@@henkoegema6390 why do I feel we are a dying species? A lot of complaints in the comment section about those beeps...

[@henkoegema6390]

@@Sekir80 The beeps are too complicated for most people.

[@Sekir80]

@@henkoegema6390 Then maybe I'm really a freak. If i'd hear the same bleeping I'd not give it a second of thought. But if I hear it is different in every chapter without any seeming logic (ie 1 bleep for chapter 1, 2 for 2) I'd try to figure it out. Or at least think about it as something that might have meaning and not dismiss it as "those load beeps sux, man!". I'm really a freak. For sure. Sorry 'bout that, guys! :D

[@AndreasSpiess]

Glad you enjoyed it!

[@princeoftheblues]

I invented this. Too bad I am so lazy. But what this is really good for is the freewheeling diode on a buck converter. That is, if the switching frequency isn't too high. Those diode losses are serious. Especially in big stuff like cars. But for protection against reverse polarity you can always just use a diode that will short it out, like a crowbar, and blow the fuse. You would need a fuse. No forward drop! Cheap! But need that fuse.

[@AndreasSpiess]

I agree with the crowbar. Unfortunately, my "ideal" diodes were not very good with 50Hz sine waves. This is why I did not mention this use case.

[@theoldbigmoose]

Love your presentations... please DITCH the LOUD morse code malarky. Your too good and professional for that kind of stuff

[@AndreasSpiess]

Thank you for your feedback!

[@tonyh6309]

LCSC has a good selection of 'ideal' diodes many with the FET included on chip, found under Products/Power Management (PMIC)/Synchronous Rectifier Controllers. They are *MUCH* cheaper than TI and LT parts - eg. the DK5V100R15S, a 2 terminal 100V, 15milliohm part is only $0.3 @ 100 off. The datasheets tend to be *very* sketchy, or in Chinese only, so you'd need to be prepared to do a lot of testing to understand their limits. (Eg. avalanche and max dV/dT ratings for the MOSFETs) As others have pointed out, all 'ideal' diodes have limitations in replacing standard diodes, especially wrt the speed at which they can turn off. Eg. most are too slow to replace the diode in a non-synchronous buck converter in CCM mode or they are only suitable for relatively slow switching regulators. Also many 2 terminal parts require a reverse voltage to provide their operating power so won't work in a DC application. The $0.23 NDP7935KC looks interesting with an integrated 8milliohm 60V MOSFET with a fast 12ns turn off time (typical only soec) - but that is actually the time to switch the gate of the MOSFET so the overall response might be much slower. Even the TI LM73100 might have issues when used for battery charger circuits; the fast turn off time in reverse current flow is only specified as 1us 'typical' - no maximum. Eg. consider a solar panel charging a large battery, or capacitor. What happens if the solar panel gets shorted? Depending on the inductance of the input and output wiring the battery could deliver many hundreds of amps into the short in that 1+ us. Would the device survive that? The datasheet doesn't help. Similarly when the input is connected to a battery and the load gets shorted. The LM74610 is interesting in that, whilst it doesn't require a gnd connection so it (along with an external MOSFET) can replace a diode without other cct changes, it has to get its power by periodically turning off the FET to harvest the power from the .5V drop across the MOSFET's body diode. That could be a problem if the cct relies on the low forward voltage of the diode in operation - eg. a circuit with a 3V minimum supply driven by a 3.2V LiFePO4 cell. After all that I expect that they would all work really well in a 50/60Hz linear supply replacing the bridge rectifiers which often run rather hot and waste a fair bit of power. You probably wouldn't want to use 4 x LTC4357 at $5 a pop though!

[@AndreasSpiess]

Thank you for the additional info! I did not mention 50/60Hz applications because my two devices did not behave properly in these situations and they also were not mentioned in the datasheets. My focus was more on the reverse voltage protection. Concerning the "energy harvesting": I assume there is enough capacity available on the load side if your device is sensitive to voltage drops.

[@tonyh6309]

@@AndreasSpiess A reservoir capacitor across the load doesn't help as the diode device can only harvest its energy from the .5 to .6V voltage drop across the MOSFET body diode when the MOSFET is turned off. That voltage arises from the current flowing through the body diode which means the output has to drop 0.5V or more below the input. A large reservoir capacitor merely prolongs the MOSFET off time waiting for the output voltage to drop .5V below the input. In practice that capacitor won't make a lot of difference, unless it's *very* large (compared to the load current), given that typically the MOSFET is turned on for 2.66s and off for 55ms using the recommended Vcap.

[@AndreasSpiess]

@@tonyh6309 Good point!

[@rdyer8764]

If needed, just one "beep" is best (like the last one), and a bit quieter please.

[@Sekir80]

The last one, single beep represented the letter E.

[@AndreasSpiess]

Thank you for your proposal.

[@SuperBrainAK]

I love ideal diodes! I once blew up my Rui Deng DC-DC bench supply (DP30V5A) by messing about late at night, wanted to charge up a large 35Ah SLA. I didn't look at the polarity and connected it up backwards. It sounded really bad! A spark and a fizz. The unit does power up but doesn't output anything. 😢 It was replaced with a newer RD DPS5005 and I used the included conventional diode because it isn't necessary to have an ideal one. I would just like the Ruid Deng units to have output voltage compensation.

[@AndreasSpiess]

Thank you for sharing. I never tried if they have reverse voltage protection (which they should have, I think).

[@SuperBrainAK]

@@AndreasSpiess They definitely don't The shipped a lot of them with diodes in order to connect them to batteries which was stated in the manual.

[@MatthiasWelwarsky]

For my simple, low power devices I usually go for a simple p-channel mosfet like an IRLML6402. No overvoltage protection but plenty sufficient for any micro controller board powered from a 5V source. The cost is neglegible.

[@BusyElectrons]

Same here, but my go-to has been the Si2301C. The IRLML6402 looks interesting. Similar specs but a higher Max Vgs and slightly lower Rds(on). I'll add some to my next order. Thanks!

[@AndreasSpiess]

Indeed a good solution for 5V and low current devices. And simple! Thanks for mentioning.

[@Dav_Wilson]

Loved the video we are currently looking at using idea diodes as by solar cell pass diodes for a solar race vehicle good coverage of products!

[@AndreasSpiess]

Another commenter also mentioned this application. I do not know how much the efficiency is increased...

[@Dav_Wilson]

@@AndreasSpiess Very important you are right its currently looking like ~5W when also including additional weight compared to a traditional Schottky diode

[@jps-ib8vh]

Thank you for the video. These devices are fine for reverse current blocking. Could be also nice as parallel diodes in solar panels for shunting shadowed panels. For protection I prefer a 1N4007 or the like parallel to the input and a short circuit protected power supply. The you have no voltage drop at all and you are also safe if there is a short in the cable or connector.

[@AndreasSpiess]

A good idea. Often used with a fuse in series. Sometimes called "Crowbar" ;-)

[@AJB2K3]

I have reverse polarity several time but never had spectacular fails or release of Magic Smoke (even when done on purpose), I never get to have any fun!

[@AndreasSpiess]

What a misfortune. And no high repair invoices neither (as other commenters wrote). So sad ;-)

[@MiguelDeMarchena]

I once had this dilema so i tried to make what i called the (I don't care circuit) with mosfets and relays which was designed to deliver the right polarity no matter what polarity on the input but for efficiency and cost I went back to the diode and fuse simple design.

[@AndreasSpiess]

Indeed, this is a good thing for low power devices.

[@skovgaard79]

You always do such great work

[@AndreasSpiess]

Thank you!

[@RyanJ_]

No beeps please

[@emmatitova2154]

Agree, not a fan

[@Sekir80]

That was the secret code.

[@Sekir80]

@@emmatitova2154 Indeed, not a fan. Diode.

[@geleigh]

Great video. Good reminder of diode operation.

[@AndreasSpiess]

Thank you!

[@BobHannent]

My lecturer in electronics suggested that a rectifier would be the best thing for reverse voltage protection.

[@AndreasSpiess]

I do not know your age. But a few years ago he would have been right.

[@guytech7310]

Cheap & easy solution for Reverse voltage, over voltage & surge: TVS diode & PTC Fuse. PTC Fuse on high side power source, than a TVS diode on the other side of the Fuse connected to ground. if the power supply is reversed, the TVS diode works like a diode with a forward voltage applied. causing a short. the PTC fuse will trip, limiting input current. On over voltage or surge, the TVS diode clamps down at its breakdown voltage. PTC fuse will limit current if the supply is in Over voltage. PTC Fuse is reuseable over & over as it does not blow like a standard fuse. Under excessive current it heats up & resistance increases until it reaches equilibrium. When current flow reduces the resistance falls back to a low resistant state.

[@AndreasSpiess]

A good idea. It is sometimes called "crowbar". But not often used with PTC fuses!

[@guytech7310]

@@AndreasSpiess I know what a crowbar circuit its. I designed a surge protect that uses a 3 way crowbar circuit for AC. Crowbar is uses for high power AC systems. Using the PTC + TVS diode is a much simplier circuit for DC protection.

[@michaelbruns473]

Interesting development - I don´t really have an application for it, but that does not matter. I did learn something today!

[@AndreasSpiess]

You never know when you will need it ;-)

[@y2ksw1]

I like the solar charger application. We are using both standard and Schottky diodes, but we have the suspect, the latter have a substantial backflow. With these "chinese amp" diodes, we can give it another shot. Or copy the idea by using a stabilizer and a MOSFET.

[@AndreasSpiess]

Another commenter wrote that Schottky diodes are not ideal for that purpose. I should have used "power" diodes... But an ideal diode is worth a try, I think.

[@jessstuart7495]

A single PMOS transistor can be used for reverse polarity protection. I've used this on my designs, and have seen this used on commercial PCBs.

[@AndreasSpiess]

you are right, if you use one that has a proper Vgs voltage or use a Zener diode to protect it.

[@bsod5608]

I reversed polarity connected solar panels to the inverter. Absolutely nothing happened, the inverter had reverse polarity protection, thank god!

[@AndreasSpiess]

That is probably a common mistake. Our solar cables were all black. So it is easy to mount a wrong connector!

[@Lion_McLionhead]

Lions always use fuse diodes. Ideal diodes are an interesting concept for DC-DC converters & battery chargers though.

[@AndreasSpiess]

I did not know that fuse diodes are used in professional designs. I thought they use "real" fuses. So I learned something.

[@TheMrDrMs]

That seems to be a pretty smart design

[@AndreasSpiess]

I agree!

[@shas150]

Very good video about "ideal diodes" and this chinese module was LisinYT youtube channel

[@AndreasSpiess]

Indeed. And even "autotranslate" worked quite well ;-)

[@iosifferencz5432]

Mulțumim pentru aceste informatii certe❤

[@AndreasSpiess]

Cu plăcere

[@PhG1961]

Awesome video and what a great solution from ChatGTP!

[@AndreasSpiess]

Indeed, I was astonished, too. I first asked google without success.

[@Tr0nism]

pls no more beeps

[@overamped23042]

The beeps say "diode" in Morse code. That is the secret he mentioned at the beginning.

[@Sekir80]

@@overamped23042 Some are so whiny nowadays.

[@ergindemir7366]

It depends on your source voltage, if your input is 25V a 250mV drop will result in 1% power loss.

[@AndreasSpiess]

You are right.

[@jrapplefan2231]

Could we use it as a shunt resistor to read current ?

[@AndreasSpiess]

I do not know why I would do it. And: They have an extremely low and varying resistance.

[@MrI8igmac]

Im working on 8 amp drone, 2 amps per motor. I have burnt out gpio pins and a few esp32 boards. I plan to put diode on gpio pins and diode on esp32 5v pin. I also consider capacitor on the esp32 5v power.

[@AndreasSpiess]

I hope you will use Schottky diodes on the GPIOs because otherwise, the signals can degrade.

[@RomanDvoryadkin]

Several years ago I designed one device for semi-industrial use. So for input 12V DC I installed full bridge rectifier, MOV and PTC. You can connect any voltage to it. If it in the 7-18V range (any polarity) - it will work. On higher voltage PTC breaks circuit. Below 7V MCU didn't start. But full consumption of the device below 1A so power loss on rectifier is negligible.

[@AndreasSpiess]

That was a well thought strategy! I think that many users were happy that you went the extra mile to protect them from hassle when they did a mistake.

[@RomanDvoryadkin]

@@AndreasSpiess They asked me what it means below input connector "12V AC/DC" :)

[@ghlscitel6714]

Morse code paragraph separation: "d i o d e" This dude must be a radio amateur class "Old Man".

[@AndreasSpiess]

Definitively. And I was a professional radio operator for the Red Cross when I was young ;-)

[@ghlscitel6714]

@@AndreasSpiess Respekt , 73 & 55 aus DE/Münster/NRW

[@4bSix86f61]

I found the LM74700 on LCSC which is cheaper than the ICs used on the Ali Modules.

[@AndreasSpiess]

Thanks for the hint. LCSC is a good supplier, particularly for parts because you can trust them.

[@henrybecker2842]

Welcome back. Love the Morse Code bullets 😂

[@AndreasSpiess]

Thank you. It seems that not all lover them...

[@captaintlamlam2093]

Did you place only the ideal diode between the big and the small battery?

[@AndreasSpiess]

Yes.

[@jocool7370]

Those beeps are very irritating. They're not what we want.

[@DVSProductions]

It's some sort of Morse code

[@TheDutchGuyOnYT]

It ís morse code

[@rimmersbryggeri]

I think ideally a bridge rectifier should be used in all projects with a power brick but that a UX consideration rather than an engineering one.

[@AndreasSpiess]

A bridge rectifier is a good and cheap idea. However, it has 2 diodes in the path (with all disadvantages)...

[@rimmersbryggeri]

@@AndreasSpiess Yeah that's a problem to be calculated for surely. But also you can use any power supply ac or dc as lont as it has enhough tension.

[@soufbel3455]

🌟 I need a sensor that detects a mAmps current, just detect it, I don't need to measure it, the current is about 20mA, can you advice? Nice video as usual, thank you 👍

[@lukeparker8559]

Hi Andreas, hope to see you at European microwave next week. Best regards Luke from murata / Psemi

[@AndreasSpiess]

Unfortunately, I was not aware of this event :-(

[@tomhelo4523]

Hi Andreas, very nice Video. Just a question, ist there a way to use the ideal Diode as a " Switch"? e.g from a arduino or esp Controller or a Mini mechanical Switch for Higher Power switching? Is a pin on the Chips for that purpose? Thx and 73

[@AndreasSpiess]

The chips I used did not have such a switch. But maybe others would have one. Search also for "MOSFET drivers". They are made for the switching scenario.

[@bastiannenke9613]

4:35, kinda expected you to say "lets use 5 of them". I used one of those on my first solar battery project between a meanwell HLG psu and the fuses because i was not sure if the meanwell enjoys a reverse voltage wjen powered off. Used the meanwell instead of a normal 8s charger because i could adjust the voltage, or the maximum SOC from mains since its a island system with mains fall back.

[@AndreasSpiess]

With an adjustable voltage you can use a diode, no problem (if it does not get too hot).

[@derdieterhans]

Hey, how about a video about mmwave radars which can be used for traffic detection. They are expensive but quite impressive! Check out the TI 4316 and their examples. Great stuff, impressive range of 70+ meters.

[@AndreasSpiess]

I agree, many such radars must exist becuase they seem to be rather standard in newer cars. However, they seem to be protected by the suppliers. I once investigated in using such devices from old cars...

[@derdieterhans]

@@AndreasSpiess I don't mean the front assist radars which are used in adaptive cruise control, but the ones which are used on poles or traffic lights for counting cars.

[@alexwang007]

The last scenario uses what is called a power OR-ing circuit, relating to logical OR-ing

[@AndreasSpiess]

You are right!

[@Beatfreak19831]

Diode 👍😁

[@AndreasSpiess]

Bravo!

[@mvdswaluw]

@@AndreasSpiess Next time send the morse code at a frequency > 12kHz. Secret for OM's and still a challenge for young HAM's.

[@RuddODragonFear]

@@mvdswaluw GOOD TIP!

[@jmr]

​@@AndreasSpiessBeyond the Morse code you saying "front row" instead of "first row" seemed strange. Just a slip up though?

[@AndreasSpiess]

@@jmr No, this is a suggestion of my correction service. I correct all my scripts with Grammarly to use correct American English.

[@hyneklos]

i like your sherlock homes mode! :)

[@AndreasSpiess]

Thanks! 😊

[@h1tec]

Great video! If you guys want an ideal diode with a power switch by using a second FET, I have posted a video on it a few weeks ago. Thanks!

[@AndreasSpiess]

Cool video. And cool channel. Subscribed!

[@h1tec]

@@AndreasSpiess Thank you so much! I’ve been watching your videos for a while now, they are great 😁

[@leocurious9919]

The graph at 02:38 is only correct with a linear scale. It will be like a nearly perfect line on a log scale. Zeners are different here, they really show a sudden change in conductivity (far faster than the otherwise exponentially rising) somewhere around their nominal voltage rating. Example data matching a measurement I made: Voltage [V], Current [mA] 0.2, 1e-4 0.3, 1e-3 0.4, 1e-2 0.5, 1e-1 0.6, 1e0 0.7, 1e1 0.8, 1e2 [getting too hot] At 03:36 you did not turn the powersupply on, by the way.

[@AndreasSpiess]

Thanks for the additional info. I switched the power on after chaning polarity, but obviously cut it afterwards. My mistake. You are a good watcher!

[@isoufacker]

do you think that they can be used to audio amplifiers ? to solar/wind power inverters ? for smaller more efficient machines :)

[@AndreasSpiess]

I tried them with 50Hz sine waves and they did not perform well. Maybe there are other ICs for such applications.

[@merkatorix]

I think I have never reversed polarity yet, but I'm paranoid about it. I used Molex plugs for my old projects and switched to USB. USB is not really replacing variable power supplies for prototyping. Although I get 28V and 5A, it probably doesn't replace those diodes. Thanks for the overview of working ideal diodes. Is there already a video about working USB decoy boards? I found so many decoy boards, which don't always work. They always provide 9V instead of any promised voltage. 20V at one power supply and 15V at the other.

[@AndreasSpiess]

I agree, USB is a good alternative. I made a video on USB in general where I explain how it works.

[@mfx1]

Iv'e used MOSFETS as diodes before but never with an additional IC not sure what extra benefit the IC offers is?

[@AndreasSpiess]

It works with higher voltages than Vgs max. , for example.

[@tullgutten]

Can always make the cheap crude version. And diode in paralell to input at reverse and a input fuse. If the voltage is reversed it shorts and blow the fuse, seen this in many circuits even expensive gear

[@AndreasSpiess]

A good idea for reverse polarity protection if you have a spare fuse handy. Not so good for the "two power supplies and one load".

[@hyneklos]

really nice video!

[@AndreasSpiess]

Glad you liked it!

[@clifforddicarlo9178]

Wiped out an ATtiny85 microprocessor by plugging it in backwards making the ground pin (pin 4) the +Vcc pin and the Vcc pin (pin 8) the ground pin. Result: dead microprocessor due to reverse polarity. Lesson: Always be aware of where pin 1 is (pint the the dot should be upper left)

[@AndreasSpiess]

The same happened here last week (mixed the two cables on my breadboard. The ATTiny became quite hot ;-)

[@insanemainstream3633]

Great video!

[@AndreasSpiess]

Thanks!

[@McShakyFPV]

I was born colorblind but how do you know? I let the magic smoke out of more electronics than I care to admit

[@AndreasSpiess]

I worked in the photofinishing industry and learned about colorblindness (and that only males get it). There, it was a killing factor for most jobs, and a test was made before the interview started. I can imagine that this can also create problems in our profession.

[@Richardincancale]

Secret codes at 1 word per 11.66 minutes! I can just about keep up with that, although the official WPM word is PARIS!

[@AndreasSpiess]

You are right. It was exactly one 5 letter word!

[@IanCliveKerrCoelho]

Diode in morse.... Cool!

[@Sekir80]

Interesting. There are fewer likes on the answer to the secret message than for the whiners "no more beeping". :/

[@AndreasSpiess]

Congratulations!

[@jamesphillips2285]

My largest smoke incident was probably installing a 486 CPU backwards. After I managed to pull the CPU out of the damaged ZIF socket: I saw what appeared to be solder around one of the pins.

[@Sekir80]

How did you do that? If I remember correctly the socket and CPU was coded in a corner leaving 2 pins out from the grid forming a point, or arrow.

[@jamesphillips2285]

​@@Sekir80 While the socket has a key pin: you can see it is not actually used by the CPUs if you look up pictures of 486 CPU pins. I made sure to line up the mark on the package properly after that incident!

[@AndreasSpiess]

Indeed an expensive mistake! I think, such a mistake is no more possible with newer sockets.

[@jamesphillips2285]

@@AndreasSpiess 486 CPUs were not actually that expensive at the time. I think the Pentium II was the new hotness.