TWO_SIMPLE_TEMPERATURE_TO_TIME_CONVERTERS

Published:2009/7/7 23:55:00 Author:May | From:SeekIC

Both of these converters use CM0S inverters. Figure 105-1A shows a free-running circuit having both the pulse duration and pulse pause dependent on temperature of the diode DS. It can be used where a synchronization between the converter and something else is not required. Figure 105-1B shows a one shot circuit that produces a pulse with its duration dependent of temperature of diode DS. The additional diode Df should have inverse current low enough to not influence the discharging process in the network rc when the INVA output is low. A silicon component or a GaAsP LED can be used.The converter is intended for a digital system producing a RADY pulse which disappears after the conversion process is ended. The pulse duration is approximately:where VD is the sensor diode forward voltage and VDD is the supply voltage of the CM0S chip.Resistance R must be much higher than RS A 0.1-μF capacitor can be applied in parallel with DS, if necessary, to repulse stray pickup and noise in a long cable. The circuits described can be used with a temperature sensitive resistor instead of the diode DS.



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