So hopefully an easy question.. I'm not familiar with this type of IC but I have accidentally fed it 12vdc I believe to the VSS side. I'd rather not embarass myself by explaining how.. From what I can tell the `24` should signify the expected input voltage. Judging by the datasheet 12V is the Maximum but if my bench power supply is putting out 13vdc.. what are the chances I killed it? The only equipment I have is a dig MM so no scope to help diagnosis.. even I I knew how.

https://www.mouser.com/datasheet/2/360/S808xxC_E-1501400.pdf

Thanks!

 

I'm going to say even if it was connected correctly you would have killed it. Absolute maximum ratings are exactly that... the absolute maximum. If you connected it reverse polarity maximum ratings don't even apply... it's pretty rare for something to survive even at a fraction of it's maximum when connected backwards.

 

I have no idea if it was connected backwards.. Im assuming by looking at the schematic and the datasheet that VSS is the input pin. But yeah I get you on the reverse voltage. I can't get the device apart enough to even inspect this component visibly. But I will not set my expectations high in further testing.

 

The data sheet you linked showed two operating voltages:



If you used the 0.65V to 5.0V chip then you most certainly blew it up. If you used the 0.95V to 10.0V chip and over voltaged it chances are you may have blown it. If you reverse connected it - there's a chance that an internal diode may have protected it, but I didn't see anything in the quick scanning of the data sheet.

Often people speak about 12 volts. In an automotive condition, voltages can go as high as 15 volts for a short period of time but then settle down to around 13.8V. And a new automotive battery will rest at around 12.6 to 12.7 volts. Older batteries will rest at lower voltages due to wear. A nearly worn battery will drop to a resting voltage at or below 12 volts. If you want a 12 volt regulated power supply then you'll need at a minimum of around 14.5 volts, that's called headroom. Typical LM7812 regulator will need 14.5V supply minimum in order to maintain a steady 12V output. And that output can vary as much as half a volt either way.

 

... the `24` should signify the expected input voltage...

Nope, the "24" is the threshold in tenths of a volt, i.e. 24 => 2.4V DC. Datasheet table 13 says the absolute maximum applied voltage for a part with this threshold is 12V, above that the device may be destroyed. Your hope is that they have some margin on that, but no guarantee. Yes, your 13V may have destroyed the part, but maybe another will live to 15V. No way to tell without careful testing. How much ripple is on your 13V supply? Does the peak reach 14V? It could still be 13V average and hit 16V. No way to tell with a multimeter. I suggest you invest in any oscilloscope that is somewhat calibrated, even a $45 one could save you a lot of grief. With a nice probe mine ran $54 delivered.

I didn't fully chase your part number, is it an open-collector part? If so it needs a pullup resistor (to 5V would be good) such that you can see the output swing.

And a basic question: These LV detector chips are meant to go on low voltage supply rails to hold something in reset as the supply goes up and down. As such the supply nominal is seldom more than 20-25% above the chip maximum threshold. With a 2.4V threshold I wouldn't even put this on a supply over 3.3V nominal, so what gives with using 12V?

 

Im assuming by looking at the schematic and the datasheet that VSS is the input pin.

VSS is always ground. VDD is your positive supply pin and also in this case the input. OUT is your output signal.

 

Often people speak about 12 volts. In an automotive condition....

Not to nit pick, but the TS did mention a bench power supply in the original post.

 

If you think of automotive as 12V expect your project to be blown up in a real car. A weak battery may charge at 14V or more. A bad regulator may shoot up to 18V, as it did on one of my cars. (Under acceleration the ignition mucked with the regulator, the voltage jumped, and the electric power steering assist shut off to protect itself. Not fun while merging uphill onto a curved expressway. Solution: better grounding of the ignition coil module.) Double battery winter jumps hit 24V for a chunk of a minute, and a load dump can hit 35-40V for a good portion of a second. Much shorter spikes can hit + or - 80V or more. And a reverse battery mistake can power you with a negative "12V" feed. One's design really needs to tolerate all this crap or expect to replace your stuff now and then.

 

VSS is always ground. VDD is your positive supply pin and also in this case the input. OUT is your output signal.

To be more specific than "ground", Vss is the lowest voltage point of the device. and it is NEVER a signal input point.
Along with that, Vdd or Vcc are positive power input designations.

 

Not to nit pick, but the TS did mention a bench power supply in the original post.

Nit Picking accepted. And it's important. This keeps the thread on target.

I have many 12 volt supplies. Most of them are spot on 12 volts, a few of them drift a little higher when not loaded and drift lower when heavily or overloaded. I have a 12 volt supply that is actually 13.8V @ 19A. So even though we're talking about a power supply we still have to consider that there are differing types of supplies. The old transformer / bridge rectifier / filtered supply will likely have a transformer somewhere in the realm of 9 volts. 9V RMS full wave rectified (with diode Vf drop) and filter cap works out something like this:
9.5V RMS x 1.414 = 13.433 Vp (peak volts)
13.433Vp - 0.6Vf - 0.6Vf = 12.233 unloaded volts.

Using a switching power supply 12 volts remains pretty constant until you reach and exceed the amperage capability of the PS.

Home brew PS using LM7812 regulator can give a fairly constant 12V - again until you reach and exceed its capabilities. Then you start to overheat the device. The more headroom you have the more heating you get. An LM7812 needs a small headroom of around 2.5V. So if you have a 14.5 volt source feeding an LM you'll get the most efficiency out of it. That's not to say it's efficient. It is still dissipating 2.5V as heat. If you run 16 volts you are dissipating 4V as heat. Almost twice the heat energy. And you will need to manage the heat with heat sinks and possibly fans. Switching power supplies (SMPS = Switch Mode Power Supply) is the most efficient and consistent way of powering a project. Provided you're not drawing tons of amperage or wattage.

OK, that was a bit off topic, and a bit of a rant on my part. My apologies. Is your S-80824KNUA dead? Hard to say. If you reverse powered it - it may have its own internal reverse voltage protection. But even that has a limit on what it can handle. If you blew through the protection then you blew through the chip as well. I'll say the most important part of that sentence again: - IF -. It's a little difficult to tell if your chip is blown from my work bench location. If you can test it then test it. If not - build your project with a socket for the chip. Wire it correctly and verify verify verify the wiring before you power it. Then plug the chip in. If it works - guess what you didn't blow up! If it doesn't work - - - .

Given - the data sheet spoke of two different chips; one that operates up to 5V and one up to 10V. 12 or 13VDC wired correctly or backwards may have spelled doom for that chip.

 

I remember powering 11 74HC logic IC's with -48 volts, (telecommunications equipment) by a misswire on my part. I was convinced they were bad once the 2 indicators had proved it. The first was the crack across the top of every chip and the second was the smoke that exited the cracks just milliseconds after I applied power. They did not survive, your part may or may not have as has been pointed out, you only have testing to determine that, in my case, no testing was needed, just an IC puller... Good luck.

 

Agree. Not all failures present as visual evidence. Build. Test. If it works then the chip is not blown. If not - make sure your build is done correctly. If built correctly and it doesn't work then replace the blown chip. End of story.

 

Many times I get the complaint from those who don't understand. The tell me it does not work but ai do not see any burned up parts, so they must all be OK. OR, even worse, they see one burned part and think that must be the cause of the failure. So they replace the burned part and the replacement burns up. Guess what folks, that was the victim, not the bad guy.

 

To be more specific than "ground", Vss is the lowest voltage point of the device. and it is NEVER a signal input point.
Along with that, Vdd or Vcc are positive power input designations.

I always hesitate to say ground as in many cases "ground" would actually refer to safety / machine / earth grounding. On the other hand though it's also a universally recognized term for 0 V to most people in cases where there is no other grounding. It's kind of like slip joint pliers and Channel Locks, but in reverse.

As far as Vss being the lowest I have to ask what happens with negative voltages? Normally I see them listed as -Vcc, -Vdd, and such and 0 V as Vss. Numerically it's not the lowest voltage in that case, but it's not every day that people work with negative voltages either.

 

Negative voltages are lower in that they are less positive. and I don't recall seeing a "-Vcc" ever. It could be corect for a PNP device but not an IC connection.

 

I always hesitate to say ground as in many cases "ground" would actually refer to safety / machine / earth grounding.

Goes hand-in-hand with the universal misuse of the Earth GND symbol !

 

A very good friend of mine, (Rich Hartley) says, "Ground is where you grow potatoes", chassis ground is connected to it, and ground in a circuit is the return path. It's all in how you look at it. Common return path is just that, but everything else is a voltage whether it is a positive or negative with respect to the return path... Perspective... Sorry, got off the subject a bit, but I'm a train guy too, sometimes I get off the rails...

 

Maybe we need a new symbol for "Common".

 

The solution is to use the word "common" instead of the word "Ground", no new term to be needed.
Already, for PCB artwork generation, the ground symbol was not used for the program they had where I worked, since on a PCB the common needed to be explicitly defined. and in these forums, using common would avoid confusing those who are not yet aware of what is actually intended. So switching to a less ambiguous term will be an improvement in communication.

 

Maybe we need a new symbol for "Common".

The solution is to use the word "common" instead of the word "Ground", no new term to be needed.

Didn't say "Word" I said "Symbol" for common. IDK, maybe something like this:

The "Common Ground" still has the connotation of being a ground when it's more a "Common" than a ground. It COULD be a ground point, but then that's more likely to be a Chassis Ground than a Common Ground. Having a symbol for Common might alleviate the confusion. Besides, ground is nothing more than a zero point reference. You can have a machine with a chassis ground that could be several thousands of volts above absolute zero. To me - absolute zero Kelvin would indicate zero volts since there is no activity whatsoever in an atom. An atom above zero K would have some sort of an electron activity or electron volt, hence not a true "Zero".

Calling it common takes the notion of grounding out of the equation. No?

[edit] By the way, that last symbol is not an official symbol, it's something I just made up on the fly. [end edit]