[volt-nuts] Trimming the LTZ1000 tempco
bruce.griffiths at xtra.co.nz
Fri Oct 7 07:01:28 UTC 2011
Andreas Jahn wrote:
>> It seems that the page 6 trick slightly reduces the tempco but it
>> still stays in the 50ppm/C area. Or I have forgot something in my
>> calculations. I don't have a spare LTZ1000 available at the moment to
>> run the tests but maybe Andreas has time in the future.
> But consider: a resistance change on the 200R resistor of page 6
> will directly affect output voltage. 200R * 5mA = 1V.
> A 100 ppm change of the 200R Resistor has a 1V/8.2V = 12 ppm change on
> output voltage.
> All other resistors have below 1ppm change with 100ppm resistance change.
> So the 200 Ohms resistor will be the most critical for tempco and
> ageing in the whole system.
> So in my opinion its only worth to consider if you really need to save
> the 20-30 mA for the heater.
> With best regards
Except that in your case you should only need around 10% of 200 ohms
with a correspondingly reduced sensitivity to the tempco of this resistor.
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