![](https://www.richis-lab.de/images/REF01/19x01.jpg)
Of course I had to take some pictures of the ADR1000 too.
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/xgrin.gif.pagespeed.ic.QVVz6XIT20.png)
Special thanks to harerod (
https://www.harerod.de/) for donating the part.
![ThumbsUp :-+](https://www.eevblog.com/forum/Smileys/default/icon_smile_thumbsup.gif.pagespeed.ce._JElyJQqdB.gif)
![](https://www.richis-lab.de/images/REF01/19x02.jpg)
![](https://www.richis-lab.de/images/REF01/19x04.jpg)
![](https://www.richis-lab.de/images/REF01/19x07.jpg)
In the ADR1000 pin 4 is connected to the case. In the LTZ1000 (
https://www.richis-lab.de/REF03.htm) the case wasn´t connected to pin 4 directly. There was just a connection through the substrate.
![](https://www.richis-lab.de/images/REF01/19x16.jpg)
The die attache is done with some glue like material.
LTZ1000 was soldered which gave you a temperature resistance of 80K/W.
LTZ1000A was glued with some special fluffy polymer you can see in the LT1088 too (
https://www.richis-lab.de/LT1088.htm). The temperature resistance was risen to 400K/W.
For the ADR1000 216K/W had to be good enough.
![](https://www.richis-lab.de/images/REF01/19x20.jpg)
A very clean edge! Perhaps it´s normal. Perhaps they expended effort to get cleaner edges since impurities due to sawing of the wafer can worsen the stability?
![](https://www.richis-lab.de/images/REF01/19x19.jpg)
Analog applied two layers of metal.
![](https://www.richis-lab.de/images/REF01/19x05.jpg)
![](https://www.richis-lab.de/images/REF01/19x08.jpg)
ADR1000 is quite similar to the LTZ1000 but the heater structure is much simpler, no more spare structures.
![](https://www.richis-lab.de/images/REF01/19x06.jpg)
Let´s take a closer look at the circuit. There are two additional bondpads leading to the reference circuit.
![](https://www.richis-lab.de/images/REF01/19x13.jpg)
![](https://www.richis-lab.de/images/REF01/19x11.jpg)
![](https://www.richis-lab.de/images/REF01/19x12.jpg)
With the two metal layers the circuit is a little harder to read...
![](https://www.richis-lab.de/images/REF01/19x14.jpg)
The active parts are the same as in the LTZ1000 but here we have the possibility of a 4-wire-connection! VREF and GND are connected a second time directly at the zener-transistor-combo so the bias current and the traces conducting the current don´t interfere with the reference voltage. The sense traces are connected to the two unused bondpads.
![](https://www.richis-lab.de/images/REF01/19x15.jpg)
Trying to clarify the connections.
![](https://www.richis-lab.de/images/REF01/19x17.jpg)
![](https://www.richis-lab.de/images/REF01/19x18.jpg)
And of course I had to light it up (5mA).
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/xgrin.gif.pagespeed.ic.QVVz6XIT20.png)
It looks like the light is more uniform than in the LTZ1000. Perhaps here we see one reason for the lower noise figure? A more uniform structure in the buried zener?
https://www.richis-lab.de/REF19.htm ![Tweak :-/O](https://www.eevblog.com/forum/Smileys/default/smiliey_cal.gif.pagespeed.ce.yYMcAvxBJk.gif)