That is a pretty interesting idea.
Hello,
See Pickering patend.
But in my case I only increase the setpoint.
Some measurement values from the setpoint excitation on LTZ#5 with LTZ1000A:
first:
Current for the whole unit measured between battery and the voltage regulator.
After changeing setpoint it needs the full 10 minutes to finally stabilize for the current.
When setting the low setpoint it needs several seconds (around 10-15s) until the heater is switched on again.
(The rest of the cirquit consumes around 7mA).
The difference between high (around 90 deg C) and Low (around 50 deg C) temperature is around 8mA in current in steady state.
So having around 0.2 mA / deg C. (most probably not linear).
2nd:
Zener output voltage (unbuffered).
On heating the output voltage rises quickly (within 2 seconds until less than around 2ppm of final value).
On cooling down we have the 10-15 sec delay until the zener output is near stability.
Voltage rises from 7204 mV to 7220 mV (around 2220 ppm) or 54 ppm/deg C.
By the way: the "step" within the curves is due to the fact that the 2 resistors are switched on/off with around 4-5 sec delay one after the other.
The X-axis of the voltage measurements is number of measurements with 10 NPLC+offset compensation (0.4 sec/measurement).
3rd:
Setpoint voltage (measured over 1K Resistor).
Setpoint voltage behaves inversely with temperature.
At ~50 deg C we have 533.3 mV
At ~90 deg C we have 451.4 mV
Again the cooling phase needs longer whereas the heating phase goes "instantly".
With best regards
Andreas