Motorola Corporation

Jeffery T Barylak

Brian R Kemper

Mark X Stavropoulos

The output terminals (15, 16) of an analog sensor (14) are monitored by a microprocessor (17). The microprocessor is DC coupled to a main analog ground terminal (16) of the sensor, while also separately being connected to a main power ground terminal (13) at which ground reference potential is provided to the microprocessor. A resistor (38), a semiconductor switch (36) and a printed circuit board metalization trace (35) provide a normal low resistance connection between the main analog sensor ground terminals (20) and the main power ground terminal (13). Current sensing circuitry (33) limits the current passed through the low resistance connection and thereby prevents excessive current from damaging printed circuit board metalization paths (34, 35) connecting the sensor analog ground terminal (16) to the main power ground terminal (13). Also, additional circuitry (32) is provided for independently sensing the voltage at the main analog sensing ground terminal (20) and preventing an excessive voltage at this terminal from being coupled (via 22) to the microprocessor. During non fault operation, the above provides low resistance, low offset voltage connections between the sensor output terminals (15, 16) and the microprocessor (17).

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Palatine, IL, United States of America

Jeffery T Barylak