Patent ID: 7550938
Filing Date: 2009-06-23
Classification: G01D

Abstract:
1. A mechanical-electronic position sensor comprising: a housing; an actuating plunger; a potentiometer operatively connected the actuating plunger; an output stage; a DC current supply device configured to supply at least one supply voltage; and a digital-to-analog converter; a microcontroller configured to measure, as a digital value at a data output of the microcontroller, a wiper potential present at a wiper of the potentiometer, the wiper potential corresponding to an instantaneous position of the actuating plunger, the data output being connected via the digital-to-analog converter to the output stage and configured to output an electrical output signal substantially proportional to the wiper potential, the microcontroller including a first watchdog signal output configured to output a dynamically changing periodic first watchdog signal having first interruption intervals applied thereto, the microcontroller including a second watchdog signal output configured to output a dynamically changing periodic second watchdog signal having second interruption intervals applied thereto, the second interruption intervals being offset in time from the first interruption intervals; a first monitoring stage including a first output and including a first charge storage device capable of being regularly discharged by a first charge pump, the first monitoring stage being connected to the first watchdog signal output, the first monitoring stage being configured to pass the applied supply voltage through to the first output when the dynamically changing periodic first watchdog signal is present, the first output being connected via a first diode to a current supply terminal of the output stage and configured to pass the applied supply voltage through, the first monitoring stage being configured to block the applied supply voltage when the first watchdog signal is interrupted, the first monitoring stage being connected at the first output to a first read-back input of the microcontroller so that in an event that the first monitoring stage fails to block the applied supply voltage during the first interruption interval, the first watchdog signal remains interrupted; and a second monitoring stage including a second output and including a second charge storage device capable of being regularly discharged by a second charge pump, the second monitoring stage being connected to the second watchdog signal output, the second monitoring stage being configured to pass the applied supply voltage through to the second output when the dynamically changing periodic second watchdog signal is present, the second output being connected via a second diode to the current supply terminal of the output stage and configured to pass the applied supply voltage through, the second monitoring stage being configured to block the applied supply voltage when the second watchdog signal is interrupted, the second monitoring stage being connected at the second output to a second read-back input of the microcontroller so that in an event that the second monitoring stage fails to block the applied supply voltage during the second interruption interval, the second watchdog signal remains interrupted.