[volt-nuts] Thaler references

shalimr9 at gmail.com shalimr9 at gmail.com
Fri Sep 30 00:26:57 UTC 2011


Just a note in passing.

Through this group, I found out about Thaler who made precision voltage references. I ended up recommending using a VRE4100 (in the most expensive grade) in a military program with several hundred units. It worked perfectly.
 
Several years later, the same customer comes back for several hundred more, but now that Thaler has been bought by Cyrrus Logic, apparently some of the secret sauce was not transferred and now CL cannot make that best grade of parts, no matter what the price we would be willing to pay. 
So we did the next best thing, we designed in an LTZ1000 (thanks to this group again).

The mod was a little painful since the LTZ1000 requires a few more parts around it and since we have to be able to run at very low temperature, we had to boost the supply voltage to make sure the heater would not run out of headroom, but its all working now.

So I want to express my heartfelt thanks to this group (and time-nuts since that's where it started) for the collective wisdom and sharing.

In the process, I developed a rough LTSpice model for the heater circuit using an arbitrary behavioral voltage source to simulate the effect of heater temperature (via the heater power and the thermal resistance from the LTZ1000 data sheet) on the Vbe of the two transistors, so that the heater regulator loop can be closed. Even though I used 2N2222 models for the 2 NPN in the LTZ1000, the simulation shows the heater voltage and the temperature match closely with the actual unit. I thought that was neat.

I will upload it to my web site when I am back at work.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...


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