felixd / ADRmu-10v-standard-adr1000

ADR1000 10V standard

ADR1000 10V standard

Scope

Low cost 10V DC reference standard in DIN 41612 modular enclosure. Based on ovenized LTZ1000 / LTZ1000A or ADR1000A zener diodes. Fits into standard 100x160mm project boxes too. The most promising strategies for configuring the zener and buffering the output are accomodated.

TODO

Align JP and R designators Remove JPB and JPH enumeration add lt5400 and other gain resistor options film -> SMD capacitor alternatives TC network trim footprint discrete push-pull driver LC filters a la mac re-test LTZ 4 vias per transformer winding

Assembly advice

Recommended 5:7 transformer (pri:sec) when using 12V input

Spec speculations

Output Voltage Stability (± µV/V):

24 hour: < 0.3

30 day:

90 day:

1 year:

Output Voltage Noise (0.1 - 10 Hz)(±µV/V rms)

< 0.02

Output Voltage Tempco (±µV/V/K)

< 0.04

Short circuit current (mA)

9-11

Power consumption (W)

< 2W

Isolation (MΩ to AC,PE)

> 10 000 MΩ

< 1000 pF

Output Protection

Output can be shorted indefinitely with battery life derating. Output protected against ESD and input up to 60V.

Temperature Range (°C)

15 - 35

Measured results

SN	U202	.1-10Hz Noise	Tempco 15-35°C	24h Stab	30d Stab	90d Stab	1yr Stab
		[µV/V rms]	[µV/V/k]	[µV/V]	[µV/V]	[µV/V]	[µV/V]
1	ADR	0.0179		0.25	0.4
2	LTZ	0.0189
3	LTZ	0.0247	-0.024
4	ADRx	0.0346	-0.133
5	ADR	0.0134	+0.015
7	ADR	0.0157	+0.032
9	ADR	0.0147	+0.156
107	ADR	0.0242	+0.049
108	ADR	TBD	+0.030
11	ADR		+0.015
12	ADR	0.0135
13	ADR	TBD	-0.024

Initial drift & burn-in

SN	PCB	U202	Powered on	Preparation	Initial ΔV	Hours to plateau	.1-10Hz noise before	Special
1	0.4	ADR1000A 2017	Jul 2021	1yr dummy circuit	no data
2	0.4	LTZ1000A	Apr 2022	none	no data
3	0.5	LTZ1000A	Mar 2022	none	no data
4	0.5SE	ADR1000x	May 2022	none	no data			Popcorn noise
5	0.9	ADR1000A 2022	Jan 2023	7d 150°C b&b
7	0.9	ADR1000A 2022	Jan 2023	7d 150°C b&b
9	0.9	ADR1000A 2022	Jan 2023	none	1.1 µV/V	310
107	0.9	ADR1000A 2018	Dec 2022	none	3.8 µV/V	640		Transplanted to 108
108	0.9	ADR1000A 2018	Dec 2022	none	3.8 µV/V	640
11	0.9	ADR1000A 2022	Feb 2023	7d dummy circuit
12	0.9	ADR1000A 2022	Feb 2023	7d in situ b&b
13	0.9	ADR1000A 2022	Feb 2023					Ultrasonic cleaned

Trim levels

The PCB is prepared for various configurations to adapt to different needs and part availabilities. Here's what I have built so far:

SN	U202	DCDC Trafo	R213 / Pin4	R214 / Pin5	R220 / Pin3	Oven divider	R225 / Iz Down	R223 / Iz Up	10V gain divider
1	ADR	Screened Wdgs	1445 95.3R	1445 61.9k	0R	1445 13 ratio	open	open	1445 2 ratio
2	LTZ	Screened Wdgs	Z201 100R	61.9k SMD Foil	SMD Foil	VHD200 13 ratio			VHD200 2.5 ratio
3	LTZ	Bare Wdgs	100R TOMC	50k S102	100R TOMC/5	TDP10k 13.5 ratio	open	230k RN73	TDP10k 2.5 ratio
4	ADRx	Bare Wdgs	100R VHP100T	TBA	TBA	TBA	TBA	TBA	TBA
5	ADR	Screen Spacer	Alpha MCY	Alpha MAY	0R	TDP10k 11.5 ratio	open	470k RN73	TDP10k 2 ratio
7	ADR	Screen Spacer	Z201?	Z201?	0R	TDP10k			TDP10k 2 ratio
9	ADR	Spacer	1445 95.3R	1445 61.9k	0R	1445 13 ratio	open	open	1445 2 ratio
107	ADR	Spacer	Z201T	Z202T	0R	TOMC10k 11.5 ratio	200k RN73	open	TDP10k 2 ratio
108	ADR	Spacer	Z201T	Z202T	0R	TOMC10k 11.5 ratio			TDP10k 2 ratio
11	ADR	Bare Wdgs	Z201T	Z201T	0R	TDP10k 11.5 ratio			TDP10k 2 ratio
12	ADR	Bare Wdgs	RCK02	RCK02	0R	TDP10k 12 ratio	1M	open	TDP10k 2 ratio
13	ADR	Bare Wdgs	RCK02	RCK02	0R	TDP10k 11.5 ratio	open	1M	TDP10k 2 ratio

ADR1000 & Vishay 1445 All-in-one Resistor Network

My SN 1 is built this way. This is a no-bainer or easy mode. When I got my first glimpse at the ADR1000 datasheet I went straight to Vishay Foil Resistors and ordered an all-in-one resistor network with all the critical resistors from the datasheet plus a simple divider for buffering the 6.62V output to 10V. By specifying at least 2 ppm/°C TC tracking for the two critical dividers I am guaranteed great performance. And thanks to the hermetically sealed DIP14 package I expect little long term drift from the resistors. This solution comes at a hefty price.

LTZ1000A & Discrete Resistors

My SN 2 is built this way. This is probably the most popular way of building LTZ1000 voltage standards. Digikey carries quite a few hermetically sealed Vishay Bulk Metal Foil resistors without MOQ these days, giving you all the design freedom. The two most critical parts are the LTZ-temperature-configration divder i.e. 13k/1k and the 7.1V to 10V buffer divder i.e. 2k/5k. For these two I used hermetically sealed Vishay VHD200 dividers. These have guaranteed TC tracking and little long term drift. The remaining LTZ-configruation resistors i.e. 70k, 70k, 120R are not very critical. For best performance you can add an additional resistor to LTZ pin 3 to improve the Vrefs tempco, see "Adjusting Temperature Coefficient in Unstabilized Applications" in the LTZ1000 datasheet. 20 Ohm seems to be a reasonable approximation, suitable for most LTZs. In my case I determined 18 Ohm to be an optimal resistor with a TC peak at the oven setpoint. Careful, this additional resistor, if equipped, has a lot of influence on zener voltage and should be of high quality.