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AFAIK, the 1/f noise of a Zener operated in avalanche mode [like the LTZ1K is], will be inversely proportional to the square root of the Zener current. So, going from 5mA to 20mA would (theoretically) reduce the 1/f noise by 1/2. I got that from my ancient Motorola Zener Diode Handbook.
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Is there any way to speak with a scientist or engineer at the factory where those Zeners were made to get some additional information on them?
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Is there any way to speak with a scientist or engineer at the factory where those Zeners were made to get some additional information on them?
I tried but no result. I cannot find anything of related publications neither. They didn't mention that 2DW233 in their website in particular(such as special process or ultra-low noise). Those low noise 2DW233 is selling at similar price(all very cheap) as other manufactures with severe noise. The low noise feature of this 2DW233 is only recognized by amateurs like me.
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Is there any way to speak with a scientist or engineer at the factory where those Zeners were made to get some additional information on them?
I tried but no result. I cannot find anything of related publications neither. They didn't mention that 2DW233 in their website in particular(such as special process or ultra-low noise). Those low noise 2DW233 is selling at similar price(all very cheap) as other manufactures with severe noise. The low noise feature of this 2DW233 is only recognized by amateurs like me.
Maybe it's just a typo
JS
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Is there any way to speak with a scientist or engineer at the factory where those Zeners were made to get some additional information on them?
I tried but no result. I cannot find anything of related publications neither. They didn't mention that 2DW233 in their website in particular(such as special process or ultra-low noise). Those low noise 2DW233 is selling at similar price(all very cheap) as other manufactures with severe noise. The low noise feature of this 2DW233 is only recognized by amateurs like me.
Maybe it's just a typo
JSIf you meant the noise, no.
There is no specification for the noise in the datasheet. The ultra-low noise feature of 2DW233 was found out by actual measurement of many people at different places and on different times.
I tried but no result. I cannot find anything of related publications neither. They didn't mention that 2DW233 in their website in particular(such as special process or ultra-low noise). Those low noise 2DW233 is selling at similar price(all very cheap) as other manufactures with severe noise. The low noise feature of this 2DW233 is only recognized by amateurs like me.
I tried to buy these from the ali-express seller you mentioned but after 75 days and no shipment I canceled the payment. .........
I tried to buy these from the ali-express seller you mentioned but after 75 days and no shipment I canceled the payment. .........
I'm sorry to hear that. I didn't know AliExpress before I came across some people at an electric unicycle forum who often buy electronic parts from AliExpress with free international shipping(which is slow). I buy most of my electronic parts at taobao.com that backstaged by the same Alibaba but has a dedicated on-line chat system allowing sellers and buyers to talk. One difference(of taobao and aliexpress with eBay) is that they don't charge/tax e-stores on per item base therefore the average unit price tends to be very low and the number of items in a e-store is huge so is the number of daily packages. These often result in poor management and poor service especially when they are short handed.
Any way, I've bought 500+ pieces of 2DW233 just in case they stop producing it using the same technique(and I may not find the ultra-low noise zener anywhere in the world in that case).
After difficulties with PWW resistors I finally finished all 4 LTZ1000 boards from TiN and started collecting data.
Almost all resistors are PWW made by Edwin except 4x 100k resistors which were out of tempco spec.
He has some manufacturing issues with potting.
Missing PWW were replaced by pre-selected Vishay UXB series resistors.
Initial measurement by 34411A/34410A is rock stable, so I used ratio measurement with 34401A and 34420A.
Very cool! I'm looking forward to your measurement results! Is that your temperature chamber on the right side of the photo?
-Ken
Data sheet thermal resistance specification for the LTZ1000 (non-A version) doesn't seem right. Looking at the "Die Temperature Rise vs Heater Power" graph in the data sheet, I see 85C rise with 0.5W of heater power which equates to 170 C/W or about twice the specified 80 C/W data sheet value. The "A" version does looks about right: ~82C rise with 0.2W is close to the 400 C/W data sheet value. Can anyone explain this discrepancy? Am I supposed to add normal circuit configuration power dissipation of the transistors & zener to the heater power when doing this calculation?
I ask because I'm leaning towards a 4-layer board layout with considerable copper pours for the leads and inner layers to equalize lead temperature per data sheet recommendation. I'm wondering what this will cost by way of heater power. To answer this, I'm trying to determine how much heat escapes by way of the leads versus the case. I thought comparing thermal resistances of the highly isolated "A" part versus non-A would yield insight. Instead, I can't seem to make the numbers add up...
Neat setup. I see my earpick trick works for you too . Will you have datalogging running as well?
Would like to see reference board pics in your setup, once you done with measurements.
And what would be the ultimate plan of using these modules? Long-term testing or some practical application, if that's ok to ask?
Usually the thermal resistance for a TO99 is about 160 K/W. Also the similar size TO39 is in that range. So I guess the 80 K/W number is wrong, or in forced air or with rather short leads.
The thermal resistance of the wire can be estimated form the dimensions and the known material. My calculation give something like 900 K/W for the 8 full 15 mm leads, and about 300 W/K for 5 mm leads. So there is quite some power going through the leads, especially if short. With extra thermal insulation around the case the heat flow through the pins can be the major part.
Due to the extra about 300 K/W extra internal thermal resistance the A version can operate with a lower heating power if the temperature is choose for the same maximum ambient
temperature. However the difference is not that big - comparing long an short leads can be a similar difference.