Part Number: LM, Maunfacturer: Fairchild Semiconductor, Part Family: LM, File type: PDF, Document: Datasheet – semiconductor. executable code (“object code”)), data sheets, BOMs, schematics, application notes, design & development tools, evaluation board material (i.e. BOM, Gerber, . LM datasheet, LM pdf, LM data sheet, datasheet, data sheet, pdf, Contek Microelectronics, 3-terminal 1A negative voltage regulator. Output.

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LM regulator doesn’t work by datasheet. LM regulator doesn’t work by datasheet Hi everyone! I have a dual supply with and I use the proper capacitors for filtering and stability by the application note ST semiconductor’s datasheet.

For the regulator ICs I shifted this voltage down with 8. And it will working well if the regulators are unloaded. With the filament load the still works, but on the ‘s OUT pin the voltage went down to V.

Actually the current in the negative branch, on the Zeners is mA, which is almost the expected value, but it datasheer interesting that the output voltage is changed INPUT voltage was V with load. Also I measured an unused with labour supply. Under V the regulated output falls down.

At V input voltage the lm912 is V, at V input voltage the dataeheet is about V.

LM Datasheet(PDF) – TI store

Only between V and V the IC worked well, so I don’t understand what is the maximum V input voltage by the datasheet. LM regulator doesn’t work by datasheet You should show the circuit diagram, but vatasheet what you have said have you put the diode in series with the ground pin of the the right way around?

LM regulator doesn’t work by datasheet Make sure that the input and common are connected correctly. It is different between the and Input and common is swapped on the compared to the Is it a true “LM” or a dtaasheet source one? Originally Posted by pjmelect. You should show the circuit diagram, but from what you have said have you put the diode in series with the ground pin of the the right way around?

Originally Posted by KlausST. Hi, Show schematic and PCB. Originally Posted by E-design. Make sure that the input and common are connected correctly. LM regulator doesn’t work by datasheet Hi, I wonder why it is so difficult to post your schematic. But you are not alone with this behaviour.

LM7912 Datasheet

We – those who want to help – need informations about your schematic. Not the schematic from the datasheet. The schematic of the datasheet should be verified, and it is very likely that it works as it should. Therefore we need information that are not in the datasheet schematic. Your input power supply, your modifications, your load informations. Last edited by KlausST; 18th February at Replaced capital letters with underlined letters.


LM regulator doesn’t work by datasheet Hi, not so difficult, sorry, but I thougth a 3 terminal regulator circuit I can describe in words. Capital letters are equivalent of shouting as rules say, it is not necessary. I will attach schematic for you. LM regulator doesn’t work by datasheet I agree, that the standard 3 terminal circuit can be well described in words.

With your diode supplements, we would need more words to see clearly how e. Regarding capital letters, I empathize with a certain unhappiness about long winded collection of very basic information. LM regulator doesn’t work by datasheet Hi, Sorry, the capital letters were not meant as “shouting”. It was just to highlight that the datasheet circuit is about useless. To comply with the forum rules I replaced the capital letters with underlined letters And: FvM mentioned a defective device.

But I had a similar problem with a LM regulator doesn’t work by datasheet I’m aware of a possible problem with 79xx negative voltage regulators that is brought up if they drive a load connected to a positive supply node. The output may be reversed and latch to a small positive voltage in this case. Output schottky clamp to ground can prevent it safely.

But I don’t see how an output voltage magnitude above rated voltage can ever happen with a healthy device.

LM regulator doesn’t work by datasheet Thank you Klaus! Could you describe it more? The “second source” type. I don’t understand it. And what is the special load configuration? How your power up sequence solved it? FvM your solution is unbreakable, but it is still interesting that I measured a very new IC with labour supply, because before this my soldered inan other device produced the same error, that with V input voltage the output was V.

And I bought that IC from an other shop.

LM from Texas Instruments

So 2 same device from another shops produced this error for me actually. My soldered in device could go wrong from the V input, but the other device which I measured with labour supply couldn’t. LM regulator doesn’t work by datasheet I’m not sure if is stable without bypassing the ground diode. As a simple test, try if the behavior changes with diode just shorted. Huge output capacitor will force the regulator to start in current limit, but this shouldn’t be a problem regularly. LM regulator doesn’t work by datasheet It makes sense and seems a good idea.

I will try it, thank you FvM. But when I have tested the IC with labour supply there wasn’t diode or huge capacitor. LM regulator doesn’t darasheet by datasheet Are you measuring this supply voltage from the regulator VIN pin to its ground pin?


The regulator don’t know nuthin’ from outside its lmm7912. Are you applying a sensible minimum load current to ensure that through-leakage can be “soaked up” at the set output voltage? If tested at load, is the regulator being provided adequate cooling?

LM regulator doesn’t work by datasheet I wasn’t aware of this, but datasheet doesn’t specify output voltage for load current below 5 mA I mean to remember that quality though worked for me with zero datashewt current.

LM regulator doesn’t work by datawheet I thought on the GND line resistance, but the zener diode’s current catasheet mA, and the voltage difference is about 3.

They give 22Ohm GND resistance, it is too huge. I used about 1mm wide, 35um thick copper on the board, maximum length is about 10cm.

So I don’t think this is the cause. Minimum load current is not either. The schematic of the uses inside resistors in the feedback loop to maintain the output voltage R17,R19 on the figure.

Cooling is interesting, the IC lm7192 quite hot because I just added a small alu heatsink. But not too hot and still not explains why the regulator can’t work under V input datasgeet with the labour supply. I will try to short the ground diode then if it is not help I will buy a new one. Maybe I killed the second IC with the V input. Similar Threads LM regulator output is setting datashet to zero My code doesn’t work!

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