PS081 datasheet(47/155 Pages) AMSCO

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PSØ81

from the temperature measurement before it is used for the correction of the strain measurement.

Make sure that the bits mod_rspan & rspan_by_temp are set (configreg_01, bit 6 and 8, page ALU

in the evaluation software).

3.5.8.1

Resistors Rtemp and Rref

The sensitive resistor may be a carbon film resistor with a temperature coefficient in the range of

200-300ppm/K. The reference resistor can be a metal film resistor which have typically <50ppm/K.

Please make sure, that the temperature coefficient of the carbon resistor is not <200ppm/K be-

cause in this case the temperature measurement will not work properly.

The values for Rtemp and Rref have to be adjusted to the strain gage resistance and the kind of

bridge.

Therefore the resistors should have following values:

Normal :

R = Rsg (e.g. 1000 Ohm with 1000 Ohm bridges)

(= Half-, Full-, Quattro Bridge)

Wheatstone Bridge:

R = 0.75*Rsg

(e.g. 750 Ohm with 1000 Ohm Bridges)

Note:

The two resistors have to be connected in any case as they are used also for the comparator delay

correction. In case of no temperature measurement both resistors can be of the same type (e.g.

carbon resistors).

The sensitive resistor may be a carbon film resistor with a temperature coefficient in the range of

200-300ppm/K. The reference resistor can be a metal film resistor which have typically <50ppm/K.

Please make sure, that the temperature coefficient of the carbon resistor is not <200ppm/K be-

cause in this case the temperature measurement will not work properly..

For more information about this method of gain drift correction see application note AN021.

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