Toy box from Czesh republic got into my hands from one of my readers
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
Knowing my precision-sickness there are no less than 12 x MAB399 ovenized 7V references, which are on first glance clone of LM399 series, one MAC01 (10V trimmable reference in metal can 8-pin LTZ-style package and pair of Pt100 RTDs.
![](https://doc.xdevs.com/doc/Tesla/tesla_kit_1.jpg)
I was wondering if these MAB399 any good, as they are rather cheapies (if one can find them
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
.
![](https://doc.xdevs.com/doc/Tesla/tesla_hood_1.jpg)
Let's take a look on datasheet first..
![](https://doc.xdevs.com/doc/Tesla/MAB399_2_1.jpg)
Package is much taller (both zener can and outer plastic box), but following same style as LMx99. Nominal output voltage is bit higher, 7.25V +/-5%, same dynamic impedance <1.5Ohm, <5ppm/K TC (LT LM399 rated <2ppm/K for -A version, <1ppm/K f or regular), no max specification for noise on MAB399.
Now let's look under the hood. I milled top of the can on one of MAB399's and took quick photo:
![](https://doc.xdevs.com/doc/Tesla/tesla_die_1.jpg)
Stay tuned..
P.S. I know there is another MAB399 thread
in here, but decided not to necropost.