National Semiconductor Corporation

D V J Ravi Kumar

Gururaj Ghorpade

Theertham Srinivas

Mehmet Aslan

K Krishna Mahesh

A digital sensing device includes a sensor diagnostic system for detecting sensor fault conditions. The sensor diagnostic system including an input multiplexer applying a first burnout current or a second burnout current to a selected input channel and a near-rail detector configured to detect when an input voltage of the digital sensing device is near a positive power supply or near a negative power supply. The burnout current injection is applied without interfering with the sensor data. In other embodiments, the sensor diagnostic system may further include an overload detector configured to detect an overflow or underflow condition at the analog-to-digital converter. The sensor diagnostic system may further include a window comparator to detect when the ADC digital output is near a zero digital value. Finally, the sensor diagnostic system may further include a sensor flag generator to generate data flags indicative of sensor fault conditions.

Background sensor diagnostic for multi-channel ADC

A rail-to-rail buffer receiving a differential input signal and generating a differential output signal includes first and second amplifier circuits configured in a pseudo differential buffer structure and first and second comparators coupled to compare the respective part of the differential input signal and a first voltage and to generate select signals. Each of the first and second amplifier circuits includes first and second complementary differential input stages and the first and second comparators generate respective select signals to turn on only one of the first or the second differential input stage in each amplifier circuit depending on a value of the respective part of the differential input signal. In operation, the first and second complementary differential input stages of each amplifier circuit not being turned on at the same time.

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Bengaluru, India

D V J Ravi Kumar