| Electronics > Metrology |
| ADR1001 - Ovenized Voltage Reference System |
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| magic:
--- Quote from: Andreas on December 27, 2024, 04:20:37 pm ---But I fear for accurate readings of temperature a pull up resistor will not be sufficient. --- End quote --- IIRC the change in forward voltage from 1°C difference is equivalent to 7% change in bias current. |
| iMo:
What is interesting - the LTspice model outputs temperature in degreesC (at least it did - see the TSET sims in this thread). PS: a 50-100uA current source may help.. |
| Andreas:
--- Quote from: iMo on December 27, 2024, 06:04:04 pm ---PS: a 50-100uA current source may help.. --- End quote --- Hello, shure, but since they are connected to reference ground: how much will the additional current across the bond wires/PCB traces affect the output voltage? Is it ~ 100 mOhm * 0.1 mA = 10 uV or more? The remote sensing ICs normally have at least 2 different current levels to increase accuracy to 0.5 .. 1 deg C without calibrating the sensor. with best regards |
| iMo:
The current source should be stable and then the additional voltage drop on the traces will be constant too (my above sim shows it).. With a simple resistor there in sensor's collector the drop will vary based on the temperature.. |
| Kleinstein:
The 2 current levels would only be needed to get an absolute value. Alternatively one could use only the temerature sensor with a cold chip to get a starting point. Just looking at changes in the temperature, e.g. to compensate a TC in unheated mode could use a constant current. Chances are one could use less, like 10 µA and still have good enough a temperature signal. |
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