PrathikP

modified 6 years ago

Latching Over-Voltage Protection

309

04:56:36

Toggle the SPDT switch to change the input voltage. Push the push button to reset the latch. The circuit doesn't unlatch until the input voltage is below the trip voltage.

This is an over-voltage protection circuit that locks-out and latches when the input exceeds 10V. The lockout voltage is set by the resistor divider. The output of the divider is set to a comparator with a threshold voltage of 2.5V (TL431 can be used for this). The lockout voltage is given by

V(ovlo) = 2.5(1+R2/R1).

The output of the comparator is fed to a latch, which can be reset by pushing the push button. The latch shuts the PMOS off, thus protecting the load from an over-voltage.

Previous circuit: http://everycircuit.com/circuit/5189504508624896

Advantages of this circuit over my previous circuit:
-Uses an op amp to set the lockout voltage; therefore, it is very precise.
-Has a latching feature due to which any fluctuations in the input voltage around the lockout voltage cannot make the circuit keep turning off and on.

Disadvantages:
-More complex.
-The maximum input voltage is limited by the maximum power supply voltage of the op amp (usually around 30V). In my previous circuit, the max input voltage is limited by the Vds(br) of the MOSFET.

The reason why I haven't presented this circuit with a Vout - Vin type graph with an input triangle waveform is because this is a latching type circuit. As soon as the input exceeds the trip voltage, the circuit latches off and the output permanently goes off. The output would be 0 for any input voltage, even when it goes under the trip voltage.

published 6 years ago

kiani

6 years ago

Nice.,, you read my mind, i was thinking about the latch version..

kiani

6 years ago

How does the latch work.!? Is it to do with the +ve feed back on the second comparator.!.. This might be prine ti being triggered accidently with ripple,, noise or spikes,,,,, why not use an actual latch {a diode piggy back on a comparator } !?

2ctiby

6 years ago

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PrathikP

6 years ago

My friend @2ctiby, don't forget that the op amp is powered by a fixed 10V voltage. Input = 15V => Vgs=10-15= -5V => MOSFET is on. How did you miss that!

PrathikP

6 years ago

@kiani you suggested a latching type in the comments section in my last post.

PrathikP

6 years ago

I should have explained the latch better http://everycircuit.com/circuit/6416125961961472

PrathikP

6 years ago

Oh "master" of the FETs, you fail to see why the latch does not stay off for an input above 13.5 volts, for you are not willing to listen and learn. Again, you are forgetting that the op amp is power by a fixed 10V. In real life, if the input voltage is increased to 15V, the op amp would also be powered by that voltage, therefore it would output around 14V, keeping the mosfet off. But you fail to realise that due to your haste to be right, because of your haste to prove others wrong. I quite clearly explained that the op amp's output Cannot go about 10V in this simulation, because it is independently powered, which doesn't happen in real life. My circuit is just fine. You, however, aren't.

2ctiby

6 years ago

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PrathikP

6 years ago

And you talk about Rds on, master, but it makes no sense. Maybe you should learn about MOSFETs before asking others to learn about it. Maybe you should learn a bit of electronics and develop some analytical skills before coming here to post comments.

PrathikP

6 years ago

And learn to accept the fact that you're wrong. Humility, not ego, is what one must possess.

PrathikP

6 years ago

By the way, do you think I'm going to be affected in any way if you refuse to "help" me? Because your "help" isn't help, it's some misleading drivel. I'd be glad if you left, even if you left with the delusion that you're the master of fets. Do you realise that no one is going to respect you if you don't accept you mistakes?

2ctiby

6 years ago

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PrathikP

6 years ago

And I pointed out equally politely, and very clearly that you are wrong. You cannot even do a bit of math! You, however, drivel. You don't know how to accept your mistakes.

PrathikP

6 years ago

I understand completely that it's embarrassing to be wrong. Everybody understands that, because everybody has been there. What makes you a good person is your ability to accept your mistakes and learn from that.

2ctiby

6 years ago

[BLOCKED]

PrathikP

6 years ago

The math is clear: My friend @2ctiby, don't forget that the op amp is powered by a fixed 10V voltage. Input = 15V => Vgs=10-15= -5V => MOSFET is on. How did you miss that!

PrathikP

6 years ago

The value of Vgs for an input of 15V is 10-15 = -5, which is greater than the threshold voltage of -3V, which is why the fet turns on. And I've said this before and I'll say it again: In real life, if the input voltage is increased to 15V, the op amp would also be powered by that voltage, therefore it would output around 14V, keeping the mosfet off.

PrathikP

6 years ago

14-15= -1, which is less than Vgs(th). Therefore , the fet stays off.

PrathikP

6 years ago

And can we continue tomorrow? It's bed time where I live. @kiani, I'm going to sleep again:)

PrathikP

6 years ago

And you've been going on and on incorrectly about how my latch doesn't work. How is it that you, the master of fets, didn't start bombing the comments section with comments regarding a protective zener diode and pull-up resistor. Assuming that you know what they are and where they go. And I'm gone for good now. Goodnight. To me atleast.

kiani

6 years ago

@prathikp thanks for the link, , the mr. Schmitt, +ve feed back works ok,, howrver might be set of by spurious spikes and have not,, ,, ,, chk. This out, see if its any good...http://everycircuit.com/circuit/4890140322037760

hurz

6 years ago

@PrathikP, juat set the OpAmp output configuration to 100V for this @2cent idiot, lol. Lets see when he will come and tell you the output configuration is wrong. PMos are tooooooooooo complex for Mr @2cent he is lost and has no idea how mosfets work. His arrogance to help you is unbeatable and he loves todo that, even he is the one who needs help. @2cent is a pain in the ass if he does not see his mistake this happens again and again. He epic fails and want to help you, lol What an Idiot.

2ctiby

6 years ago

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hurz

6 years ago

i had the hope 100V is high enough for you idiot

hurz

6 years ago

You still dont get the point why voltages above 13V are making the pmosfet conducting again, but this is as @PrathikP explaint you not an allowed simulation configuration and wont happen in real life, cause the OpAmp would track with his output voltage. While you little boy tune the input voltage above 13V and wonder why the bulb starts glowing. LOL i think 100V should be high enough for you playing idiot

kiani

6 years ago

Not possible for latch to shut everything down, cause the latch would shut down as well.... Unless a relay is used to shut down the whole substation and subsequently the city.

PrathikP

6 years ago

Oh I can't stop laughing 🤣

PrathikP

6 years ago

@kiani I see you've replaced the resistor with the diode. This makes it less susceptible to noise? Interesting.

kiani

6 years ago

A resistor itself is a source of noise.....try with resistor,, the first time it goes to overvoltage, the output is 1v,, the 2nd and so on, 0 v. With a diode, goes to zero everytime.. Anyway i am thinking about something else, maybe a cross over,,,, it seems fine with a resistor..... specially that you are using a pfet.....,, with a resistor s path is open to the gate independant of opamp.. Use of diode., the fet s gate totslly depends on o/p of opamp..

kiani

6 years ago

@prathikP. Where are you prath. .. Fenland. !!? You sleep so much..

PrathikP

6 years ago

I like to get my 8 hours of sleep:)

PrathikP

6 years ago

Problem with a diode latch is that I cant use a pull-up resistor or protective zener http://everycircuit.com/circuit/5479831278714880

2ctiby

6 years ago

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PrathikP

6 years ago

And regardless of op amps, the circuit is going to work, sir. The op amp is going to be supplied with a higher voltage. If the input goes to 15V, the op amp can output close to 14V. 14-15=-1V. The mosfet stays off. QED.

PrathikP

6 years ago

Since you think that you're right, I'll give you a chance to prove yourself. Redesign this circuit to the way your useless brain thinks is right. You donkey have been going on and on endlessly with your nonsensical reasons about how this circuit doesn't work, but you never posted a correction, because there is no correction needed. Good bye.

kiani

6 years ago

Citiby is obsessive on FETs...lol....

kiani

6 years ago

@prathikP. The opamps internal supplies making the testing confuding for on lookers perhaps,,, while you sre using it as a feature to test the overvoltage happening, cause you increase the supply voltage to mske it happen, while opams supply remain unchanged... Plz. Chk. This,, http://everycircuit.com/circuit/4560804511481856

2ctiby

6 years ago

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hurz

6 years ago

@2cent, you still dont understand, @PrathikP told already at the beginning of this thread, the opamo supply will follow the voltage, its not fix at 10V, DONT YOU UNDERSTAND? Idiot, really why are you so stubborn? You are a pain in the ass, read what @PrathikP told you long long time ago, holy shit.

hurz

6 years ago

Here a last try for our handicaped idiot how this corcuit will behave in a real implementation, idiot give your best and follow this link and TRY at least to understand http://everycircuit.com/circuit/5814580459339776

hurz

6 years ago

Mr @2cent you are the biggest idiot we have on everycircuit, you think you understand something and that mean you know everything, but fact is you know NOTHING. Look for another hobby, moron.

PrathikP

6 years ago

@kiani why did you turn the input voltage comparator into a latch?

PrathikP

6 years ago

That way the circuit will never turn on again, unless we use 2's idiotic method by fixing the op-amp voltage and increasing the input

2ctiby

6 years ago

[BLOCKED]

2ctiby

6 years ago

[BLOCKED]

hurz

6 years ago

The fraud is you @2cent, what a piece of shit you are. Learn the following sentence for your life, you have to use it many times "sorry i have no idea what im takling, im an idiot and i like drivel nonsense". But say first "sorry". Just because you epic fail its not me or PrathikP who has a problem, its you Mr Messy

2ctiby

6 years ago

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2ctiby

6 years ago

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kiani

6 years ago

@2ctiby my stupod Fet mos library is what most simulators have,, si people don't have to feel suicidal after trying to go though you Fet, enlightens posts. ,, you are not jealous are you !? I was hoping you be the first ti bring us a few models.

2ctiby

6 years ago

[BLOCKED]

PrathikP

6 years ago

Sir I'm still waiting for your modification of the circuit. Where is it? Oh wait, I completely forgot! There's nothing to modify!

hurz

6 years ago

@PrathikP, dont expect he can help you in anything. Give him a circuit and he will mess it up. Thats why i call him Messy. Over years he did messing every circuit you will see. He is a nightmare and fraudster Mr Messy

2ctiby

6 years ago

[BLOCKED]

hurz

6 years ago

@2cent, stop twisting facts upside down. In all spec also for Pmos its Vgs and not Vsg. Thats why its negative which is for you additional complexity, LOL. @PrathikP, gave you already a nice formula many commonts above which you ignores till here and you seems to not understand. Vgs is just a voltage and say nothing. Vgsth is a voltage which defines in most specs a conductivity of the mosfet for 250uA in some specs its 1mA specialy from nexperia formula Philips. If you need more help then ask politely, but i would prefer you go away cuz nobody needs your ridiculous and rude inputs. And dont tell us PMOS are more complex then NMOS, LOL

2ctiby

6 years ago

[BLOCKED]

hurz

6 years ago

What you call stupid is well known and used in all specifications. You should go back to your second comment here in this thread and read what @PrathikP as told you, dont you understand his simple calculation? You continue yout stupid show, isn't that embarrasing for you to be that wrong and continue talking nonsense. Your second comment and any futher is not needed and you are going deeper and deeper into mess. Read first then ask. Stop this bullshit to call all around you as unknown while obviously your are the idiot.

kiani

6 years ago

What is the diff, PNP,,,, P type FET,,,,, in transistors ee don't call Vbe,, Veb cause its pnp,,,,, we could do and then chsnhe its sign, -Veb,,,,,, why all the complications,,,, it doesn't have to be negstive, just liwer than gate........ It is the fault of some of these new university phd students, ehom are srlected not by brain size. But by the size of momy, dady pocket size.....

kiani

6 years ago

Whats a big deal about Vth and Vto. , its obvious,, Vth = threshold voltage,, it does not exist., its a level, which Vto. Which does exist must reach. For PFet. {poor fet} to start seeing.. Vimto...

2ctiby

6 years ago

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2ctiby

6 years ago

[BLOCKED]

kiani

6 years ago

The models i have made., if yiu check the the detaiks in the setuo menu of each diode the Vth, is bern set to the value offered by data sheet..si there we can see what Vth is from the models... one needs dsta sheets ti dedign with, and a model ti simmulate with.., yiu can check if you like my modrls agsinst data in data sheets, and they follow curves closely, given the very limited parameters by EC,,.

kiani

6 years ago

As in transistors the base current is taken negative a little to remove the charge in fast switching ccts...

2ctiby

6 years ago

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2ctiby

6 years ago

[BLOCKED]

hurz

6 years ago

Why you guys messing on a foreign circuit, dont you think you should open your own thread to continue this nonsense? @PrathikP is propably not so happy about your messing here.

kiani

6 years ago

@prathk. chk. The modified irf4095., i ve readjusted and is spot on now.....thank fir bringing to my attention.

hurz

6 years ago

irf4905 you mean?

kiani

6 years ago

Yes my error typing, IRF4905,

kiani

6 years ago

Btw. @2ctiby. You just talk, snd words, and more,, do it, you csn do better.. Then do it.. Here is EC, and everything , just do it. Mske a model with +, - vgs, and vdss,, etc.. Do it.

kiani

6 years ago

Ehen it comes to doing, a nmos, you put up an led, and write 10 pages. ,

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