Author Topic: 1V zener diode doesn't even break down at 5V!  (Read 12369 times)

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Offline vortexnlTopic starter

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1V zener diode doesn't even break down at 5V!
« on: January 09, 2013, 07:07:23 pm »
I ordered a 1V zener diode from Conrad but it doesn't work for some reason. I'm powering my project using 5V but when I put the zener in backwards no current will flow even when I don't use any resistors at all! When I put it in forward bias it just drops 600-700mV...

Datasheet: http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdf

Am I doing something wrong here?

Thanks in advance,
Nick
 

Offline Bored@Work

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #1 on: January 09, 2013, 07:26:05 pm »
You don't get zener diodes that low. What you have is a normal diode intended to operate in forward direction, sold as a "zener diode".
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Offline olsenn

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #2 on: January 09, 2013, 07:28:38 pm »
I'm guessing it's a 1 Watt rated zener diode and 1V is just a typo for 1W
 

Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #3 on: January 09, 2013, 07:36:36 pm »
Well this is odd I tested all 5 of the 'zener' diodes I ordered, but one of them actually had a break down voltage of 900mV! This is kinda odd. If there are no zener diodes rated for 1V then conrad is just being naughty because they literally stated it had a 1V breakdown...
 

Offline olsenn

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #4 on: January 09, 2013, 07:39:21 pm »
I'm assuming you're measuring the reverse (break-down) voltage and not the forward voltage drop? Just checking.
 

Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #5 on: January 09, 2013, 07:42:42 pm »
Yes, I'm testing the reverse breakdown voltage. I guess this wasn't the best order I did on conrad. Do you guys know if it's a good idea to get a decent voltage reference by just forward biasing the diode?
 

Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #6 on: January 09, 2013, 07:46:02 pm »
Just to clarify, this is literally what you see when you browse the zener diodes on conrad...

 

Offline Bored@Work

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #7 on: January 09, 2013, 07:47:50 pm »
Yes, I'm testing the reverse breakdown voltage. I guess this wasn't the best order I did on conrad. Do you guys know if it's a good idea to get a decent voltage reference by just forward biasing the diode?

They are meant to be operated in forward direction, and will typically exebit the behavior as specified in the data sheet. If that specified behavior matches your definition of "decent" the answer is yes.
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Offline SeanB

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #8 on: January 09, 2013, 07:48:11 pm »
The "1V" is a silicon diode run in forward conduction. Tip is the voltage drop is the same as a lightly doped diode. The one breaking at a low reverse voltage is probably a faulty one that has contaminants on the die causing this. Not found in test as they are not tested at any reverse voltage at all.
 

Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #9 on: January 09, 2013, 07:49:13 pm »

They are meant to be operated in forward direction, and will typically exebit the behavior as specified in the data sheet. If that specified behavior matches your definition of "decent" the answer is yes.

Oh I'm sorry, what I meant to say was... Is it possible to use a regular diode as a voltage reference by just forward-biasing it...  :phew:
 

Offline jeroen74

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #10 on: January 09, 2013, 07:57:26 pm »
The German site of Conrad has a datasheet in German and that states the 1V version is just a plain diode.

http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdf
 

Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #11 on: January 09, 2013, 08:02:07 pm »
The German site of Conrad has a datasheet in German and that states the 1V version is just a plain diode.

http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdf

Too bad my german isn't that great! I guess I'll have to read the datasheet more carefully next time instead of relying on conrad's data.
Many thanks to everyone that responded, my next zener purchase won't be a fail  :-+
 

Offline Bored@Work

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #12 on: January 09, 2013, 08:03:42 pm »

They are meant to be operated in forward direction, and will typically exebit the behavior as specified in the data sheet. If that specified behavior matches your definition of "decent" the answer is yes.

Oh I'm sorry, what I meant to say was... Is it possible to use a regular diode as a voltage reference by just forward-biasing it...  :phew:

Sure, done all the time and there is no magic behind it. Same thing with LEDs. If the resulting regulator is "decent" depends on the requirements for that regulator.
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Offline PA0PBZ

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #13 on: January 09, 2013, 08:21:16 pm »
Too bad my german isn't that great! I guess I'll have to read the datasheet more carefully next time instead of relying on conrad's data.
Many thanks to everyone that responded, my next zener purchase won't be a fail  :-+

It is the same datasheet you linked to in your first post. On the first page there is a footnote (3) behind the ZPY 1. If you look at the footnote it says: "Die ZPY 1 ist eine in Durchlassrichtung betriebene Silizium-Diode". That should not be too difficult to understand for a Dutch speaking person" :)
("De ZPY 1 is een in doorlaatrichting gebruikte Silicium Diode")
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Offline jeroen74

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #14 on: January 09, 2013, 08:29:04 pm »
Quote
That should not be too difficult to understand for a Dutch speaking person"

You think? I find German quite difficult to understand while both languages probably sound very similar to people not speaking either one of them.

This particular sentence wasn't too difficult though ;)
 

Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #15 on: January 09, 2013, 11:19:05 pm »
Unfortunately german isn't really my thing, I only like to learn the naughty words  :palm:
 

Offline SeanB

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #16 on: January 10, 2013, 05:35:02 am »
We probably have left the US and UK, along with the Australian readers wondering what we were discussing........ ;)
 

Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #17 on: January 11, 2013, 06:02:15 pm »
If you want a 1V reference you can use something like a TL431 this is a 2,5V Vref and you can use a voltage divider to get 1V. They can not deliver power. In that case you need some more electronics behind it ( like an opamp and power transistor)

Also do some reading about the difference between diodes and zeners. It is in every basic electronics book.
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Offline UPI

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #18 on: January 11, 2013, 06:32:44 pm »
If you want a 1V reference you can use something like a TL431 this is a 2,5V Vref and you can use a voltage divider to get 1V.

TL431 Calculator:
http://xtronic.org/download/regulator-designer-voltage-current-shunt-adjustable/

Maybe something like the attached image. You would use a divider to get it down to 1V as PA4TIM suggested.


 

Offline Bored@Work

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #19 on: January 11, 2013, 07:14:32 pm »
The TL431 can't be easily configured for anything below it's internal 2.5 V reference.
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Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #20 on: January 11, 2013, 07:51:49 pm »
Hmm, maybe if you are at one time bored at work you can read the application notes, datasheet and a book bout opamps  :-DD
( just kidding)
I made several at 1V. But it depends wat you find easy  ;)


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Offline Bored@Work

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #21 on: January 11, 2013, 08:30:03 pm »
Pah. Your four references are all configured for 2.5 V and then you throw how many, 20, 30 more parts at it? All that for what started as a simple diode, and while this http://www.digikey.com/product-detail/en/ADR510ARTZ-REEL7/ADR510ARTZ-REEL7CT-ND/820440 can be had starting at $1.75.
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Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #22 on: January 11, 2013, 08:50:49 pm »
Yeah, indeed, very complex, two opamps and for a dollar worth of resistors. You are right, very heavy analog voodoo stuff. Is the modern EE afraid of everything more then one part (  most times named atmel or pic) ? They make the most simple things with an overload of digital stuff but two opamps and some resistors is heavy.  I'm afraid f the future of anlog design. It takes me more time to type this than to build it.
But i'm just ranting ;-)

All depends on what the topic starter wants to do. If he just wants 1V and not much accuracy he can use two resistors. If he wants to make a moderate accurate Vref he can use one TL and one sinple opamp and less then 10 resistors. If he wants to make 1.000,000V he just has to forget t for now ;)
And there are many more options
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Offline vortexnlTopic starter

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #23 on: January 12, 2013, 11:02:11 am »
Unfortunately I live in the Netherlands and I don't have that many resources when it comes to IC's and stuff. (except ebay and stuff like that)
That is why I usually like to build everything from analog parts because I don't feel like waiting 2 weeks for an IC to arrive.   :(
 

Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #24 on: January 12, 2013, 11:33:22 am »
Strange, i do not have that problem and I live in the same country.
Besides Conrad there are dozens of webshobs like Kent electronics, 
Or look here : http://www.circuitsonline.net/shops/1/name/0?type=&name=&city=&region=&country=nl

But we still do not know what you want to use a zener diode for. Where you need 1V for and how accurate should this be. Maybe there is an other way to solve this.
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Offline Bored@Work

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #25 on: January 12, 2013, 04:00:11 pm »
Is the modern EE afraid of everything more then one part

No, the modern EE is cost, energy, effort and space conscious and doesn't throw 30 parts on a board if a single 1.000V, three pin SOT-23-3 reference is easily available.

Unfortunately I live in the Netherlands and I don't have that many resources when it comes to IC's and stuff.

In this thread http://mightyohm.com/blog/2010/11/where-do-you-shop-for-electronics/ someone mentioned RS, Farnell (aka Element14) and dickbest  :-DD for the Netherlands. And someone points to a list of 120 mail-oeder shops in your neighbor country Germany http://www.mikrocontroller.net/articles/Elektronikversender

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Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #26 on: January 12, 2013, 04:50:10 pm »
Again, we first have to know what the TS needs.

Maybe 1.0V is good enough ( because of his limmited knowlegde I do not think he want up to 1 uV precsion ;-)  so probably your suggestion will be a usefull one)

The ADR510 is 1.000V plus/min 3.5 mV and if he is a beginner the sot23-3 can be a problem.
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Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #27 on: January 17, 2013, 11:18:20 am »
I never tried but I just read a IR led is a good 1.1V zener.
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Offline ConKbot

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #28 on: January 17, 2013, 12:20:11 pm »
Again, we first have to know what the TS needs.

Maybe 1.0V is good enough ( because of his limmited knowlegde I do not think he want up to 1 uV precsion ;-)  so probably your suggestion will be a usefull one)

The ADR510 is 1.000V plus/min 3.5 mV and if he is a beginner the sot23-3 can be a problem.

Oh cmon now ;) you can put SOT-23-3 on a 0.1" pad-per-hole perfboard. Its not the prettiest thing, but at least you dont need to buy an adaptor.
 

Offline PA4TIM

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Re: 1V zener diode doesn't even break down at 5V!
« Reply #29 on: January 17, 2013, 12:31:47 pm »
Hey, i solder 0603 by hand, but i have good eyes and a good solderstation. There are biginners with cheap bad solder, using S-39 and a 50W plumbers iron  >:D
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