ADR1001 - Ovenized Voltage Reference System

[magic]

But I fear for accurate readings of temperature a pull up resistor will not be sufficient.

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]

PS: a 50-100uA current source may help..

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.

[magic]

As far as I see there is no GND force/sense, all reference ground current flows through one fat trace to the two REF_GND pins.

Thermal diode current also joins this path at one point so extra voltage drop is inevitable, but not sure if you need much current there? Wouldn't 1MΩ to REF6P6 do the job?

Also, note that this trace already conducts a substantial reference transistor current, which is not stable with temperature (proportional to zener voltage). A resistor from TCHIP to REF6P6 would simply increase this current by a small fraction.

[iMo]

Simplest variant ala magic..