ADR1001 - Ovenized Voltage Reference System

[iMo]

Obviously, the output resistance has also been recognized at Analog Devices. It would have been ideal to resolve the node at the output of the opamp so that the feedback resistors could be contacted externally. However, this would have meant changing the pinout. Instead, the output stage is now connected to the bondpad via a relatively large metal surface. The connection to the feedback resistors is made via a long contact between the two metal layers. This contact is located as close as possible to the bondpad.

There is still one square worth of resistance outside the loop in addition to the whole bondwire.

Most references have no force/sense pins, but what they do is run separate force/sense bondwires to the output pin. Several types like LT1027 or MAX6250 are able to guarantee <10mΩ output resistance. AD's own AD587 uses this technique and guarantees <100mΩ.

The ADR1001 doesn't even have a load regulation spec in 10V mode...

You are right, two bondpads and bondwires to the output pin/pad would have been a small impact solution for the resistance problem.

I think ADI had not considered the ADR1001 for the 10V output mode seriously. So they did not test this mode much and let the "1R7" bug there (I identified here in DEC2022). Also the output resistance I measured in the 5V mode at that time (see the post) was around 8m\$\Omega\$, thus 5V mode was ok..
Anyhow, the grounding scheme and the issue with the output divider (and perhaps other issues people will find) is something they will deal with in the future, my bet..

PS: there are 3 "free" pins ADI my utilize in the future revisions - the one you get in my 1002 version, the "power-good" one you do not need, and the "NC" pin wired to the internal temperature sensor you do not need..

[Andreas]

Several types like LT1027 or MAX6250 are able to guarantee <10mΩ output resistance.

Hmm,

according to the data sheet the output impedance of the LT1027 is typically -0.015 Ohms (so negative).

"Note 6: Devices typically exhibit a slight negative DC output impedance of
–0.015W. This compensates for PC trace resistance, improving regulation
at the load."

with best regards

Andreas

[magic]

Sorry, my mistake. The specs are in ppm/mA rather than μV/mA, so 3 ppm/mA actually means 15mΩ and the worst case is 40mΩ.

For AD587 the units are μV/mA so 100mΩ maximum, no typical value given.

[CalibrationGuy]

I don't know if this was discussed elsewhere, but anyone use a PLCC 20 pin socket for aging/testing purposes in various test boards? I was able to order 5pcs., hope the stock is actually real. I want to test in various configs. and I don't want to kill the part by (even careful) hand soldering. If anyone has tried a socketed board for testing, I would like to know how it went.

TomG.

[iMo]

For a burn-in the socket might be ok, for "testing" (like long term measurement) most probably not.
My gut feeling is the chip requires a good thermal insulation and a flexible attachment to a pcb for best results..

[CalibrationGuy]

@iMo: I was thinking the same thing, but the gold plated socket has little fingers that press into the sides of the chip. These should allow for good stress relief. Also, I am going to insulate the top and bottom of the board just like the demo board. Either way, I'll test different configurations to see.

TomG.

[iMo]

..also mind there is still an external resistor of about 110ohm (the zener current setting, output voltage setting) required, it is TC sensitive. I measured aprox -250uV at the 10V output per its +1ohm change.

[CalibrationGuy]

..also mind there is still an external resistor of about 110ohm (the zener current setting, output voltage setting) required, it is TC sensitive. I measured aprox -250uV at the 10V output per its +1ohm change.

Thank you. I will use a low TC resistor and put it close to the ADR1001 and keep everything together under the insulating cap.

TomG.

[aronake]

I just got order update to shipped for two ADR1001AEZ from Mouser.

There is a link to a tracking number, but package not registered with UPS yet. But kind of seems like things are moving.

[JK21]

The doorbell just rang (not in the afternoon as announced, but in the morning  ) and Fedex brought me my ADR1001AEZ from Mouser. Order date 27-MAY-24.
So the deliveries are now underway!

[ITArchitect]

I ordered mine on the 13th of May and I'm still waiting but they say it's coming from the manufacturer.

[Electro Fan]

The doorbell just rang (not in the afternoon as announced, but in the morning  ) and Fedex brought me my ADR1001AEZ from Mouser. Order date 27-MAY-24.
So the deliveries are now underway!

Congrats on your delivery!

Just checking to what is involved (what would the level of complexity be) for a rookie metrology enthusiast to get one of these (a ADR1001AEZ or maybe a ADR1001E-EBZ) powered and outputting a 10 MHz signal?  How plug n play is this vs. what circuitry needs to be built around it?

https://www.mouser.com/datasheet/2/609/adr1001-3401813.pdf

Looking at Figure 45. Basic Hookup for 5 V Output (on Page 20) it appears that there is more involved than connecting a power supply and connecting the SMA to a counter.

https://www.mouser.com/ProductDetail/Analog-Devices/ADR1001E-EBZ?qs=dbcCsuKDzFVDd32CmVL%252BIw%3D%3D

Given the disclaimer:  "Images are for reference only See Product Specifications" it isn't clear there is a SMA connector   The attachment below is just a screen capture of the disclaimered item shown in the pdf.

Thanks for any guidance.

[Jacques]

Just checking to what is involved (what would the level of complexity be) for a rookie metrology enthusiast to get one of these (a ADR1001AEZ or maybe a ADR1001E-EBZ) powered and outputting a 10 MHz signal?
[..] it appears that there is more involved than connecting a power supply and connecting the SMA to a counter.

It's a voltage source, so you're getting DC rather than 10 MHz. I can see how the SMA connector could give someone the wrong impression though.

Edit: if you're in need of a stable 10 MHz, consider an oven-controlled crystal oscillator ('OCXO') or a GPS disciplined oscillator ('GPSDO'). The former only needs a high quality power supply, the latter you can buy off-the-shelf, e.g., from Leo Bodnar Electronics.

[Electro Fan]

Just checking to what is involved (what would the level of complexity be) for a rookie metrology enthusiast to get one of these (a ADR1001AEZ or maybe a ADR1001E-EBZ) powered and outputting a 10 MHz signal?
[..] it appears that there is more involved than connecting a power supply and connecting the SMA to a counter.

It's a voltage source, so you're getting DC rather than 10 MHz. I can see how the SMA connector could give someone the wrong impression though.

Edit: if you're in need of a stable 10 MHz, consider an oven-controlled crystal oscillator ('OCXO') or a GPS disciplined oscillator ('GPSDO'). The former only needs a high quality power supply, the latter you can buy off-the-shelf, e.g., from Leo Bodnar Electronics.

Thanks Jacques, I don't want to get this thread off track but I'd like to follow-up, so I'm going to start a new thread.
Thx again.  EF

New thread here:
https://www.eevblog.com/forum/metrology/metrology-100-101-projectinquiry-for-volt-and-time-nuts/new/#new

[aronake]

Anyone have any PCB designs to share for ADR1001? Ideally in KiCad or some other EDA format. Or maybe there still are too few chips around for someone to have done something yet?

[iMo]

TiN is designing a small PCB for the ADR1001 afaik, at least he shows something at his xdevs page..

https://xdevs.com/pow/adr1k1_pow/

Anyone have any PCB designs to share for ADR1001? Ideally in KiCad or some other EDA format. Or maybe there still are too few chips around for someone to have done something yet?

[iMo]

FYI - below the FRA stability analysis for the ADR1001 with the NE5531 buffer and the 5V output..