[volt-nuts] Tilting LTZ1000A
Andreas Jahn
Andreas_-_Jahn at t-online.de
Tue Nov 2 22:11:09 UTC 2010
Hello Frank,
here is my result from tilting the LTZ1000A in battery supply mode.
So connection is only at the output to a LT1043-based 2:1 voltage divider
and my 24-bit battery supplied LTC2400 based temperature compensated ADC.
Connection to the PC is via photocouplers. So the whole cirquit is floating.
To reduce drift of the ADC I had to heat the ADC to about 28 degrees with
a temperature controlling cirquit.
Since a single ADC-measurement has about 10-20uVpp noise I averaged the
measurements within 1 minute (around 330 single measurements) to get the
noise to around 1uV referred to the ADC input. (giving 2uVpp referring to
the LTZ).
For evaluation of the tilting effect I changed orientation every 10 minutes
giving
5 minutes to settle the new value and averaged the last 5 minutes.
Resulting in about 1uVpp noise referred to the LTZ.
with the offset voltage of -0.01706 mV from the voltage divider the final
results are:
Time orientation verbal. coded LTZ voltage diff to zero diff (ppm)
15:20 0 degrees pins down 0 (7143.76684 mV) ( 1.60 uV) ( 0.22 ppm)
(invalid)
15:30 90 degrees pin8 is up 1 7143.76468 mV -0.56 uV -0.08 ppm
15:40 180 degrees up side down 2 7143.76548 mV 0.24 uV 0.03 ppm
15:50 270 degrees pin4 is up 3 7143.76656 mV 1.32 uV 0.18 ppm
16:00 D-SUB up pin6 is up 4 7143.76504 mV -0.20 uV -0.03 ppm
16:10 D-SUB down pin2 is up 5 7143.76552 mV 0.28 uV 0.04 ppm
16:20 0 degrees pins down 0 7143.76524 mV 0.00 uV 0.00 ppm
(zero)
16:30 D-SUB down pin2 is up 5 7143.76548 mV 0.24 uV 0.03 ppm
16:40 D-SUB up pin6 is up 4 7143.76400 mV -1.24 uV -0.17 ppm
16:50 270 degrees pin4 is up 3 7143.76580 mV 0.56 uV 0.08 ppm
17:00 180 degrees up side down 2 7143.76508 mV -0.16 uV -0.02 ppm
17:10 90 degrees pin8 is up 1 7143.76440 mV -0.84 uV -0.12 ppm
17:20 0 degrees pins down 0 7143.76516 mV -0.08 uV -0.01 ppm
The result at 15:20 is off against 16:20 and 17:20 so I decided to exclude
it from the evaluation.
Since all values are near or well within my noise figure I cannot really
tell wether
the values are real or simple accidently. But all changes are below 2uV or
0.3ppm.
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