Sensor integrated circuits and methods for safety critical applications

Patent metadata

Field	Value
Publication number	US-10380879-B2
Application number	US-201715622459-A
Country	US
Kind code	B2
Filing date	Jun 14, 2017
Priority date	Jun 14, 2017
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A sensor integrated circuit includes at least two processing channels responsive to the same or different analog input signals to generate respective processed signals. The two processing channels are non-homogenous and, in some embodiments have different processing accuracies. A checker circuit receives the first and second processed signals and is configured to detect a fault in the sensor integrated circuit when the first and second processed signals differ from each other by more than a predetermined amount.

First claim

What is claimed is:

1. A sensor integrated circuit comprising:
a first processing channel responsive to a first analog signal to generate a first processed signal, wherein the first analog signal is provided by a first type of magnetic field sensing element;
a second processing channel responsive to a second analog signal to generate a second processed signal, wherein the second processing channel is non-homogenous with respect to the first processing channel, and wherein the second analog signal is provided by a second type of magnetic field sensing element that is different than the first type of magnetic field sensing element; and
a checker circuit responsive to the first processed signal and the second processed signal and configured to detect a fault in the sensor integrated circuit and generate a fault signal indicative of the fault when the first processed signal and the second processed signal differ from each other by more than a predetermined amount, wherein the checker circuit comprises a first sample circuit configured to sample the first processed signal and generate a first sampled signal, a second sample circuit configured to process the second processed signal and generate a second sampled signal, and a window comparator responsive to the first sampled signal and the second sampled signal and configured to generate the fault signal.

2. The sensor integrated circuit of claim 1 wherein the first processing channel has a first accuracy and the second processing channel has a second accuracy different than the first accuracy.

3. The sensor integrated circuit of claim 1 wherein the first processing channel comprises at least one different circuit element than the second processing channel.

4. The sensor integrated circuit of claim 1 wherein the first processing channel comprises a circuit to generate the first processed signal according to a first sensing methodology and the second processed signal comprises a second circuit to generate the second processed signal according to a second sensing methodology that is different than the first sensing methodology.

5. The sensor integrated circuit of claim 1 further comprising a single semiconductor die configured to support the first processing channel, the second processing channel, and the checker circuit.

6. A sensor integrated circuit comprising:
a first processing channel responsive to a first analog signal to generate with a first accuracy a first processed signal, wherein the first analog signal is provided by a first type of magnetic field sensing element;
a second processing channel responsive to a second analog signal to generate with a second accuracy a second processed signal, wherein the second accuracy is different than the first accuracy, and wherein the second analog signal is provided by a second type of magnetic field sensing element that is different than the first type of magnetic field sensing element; and
a checker circuit responsive to the first processed signal and the second processed signal and configured to detect a fault in the sensor integrated circuit and generate a fault signal indicative of the fault when the first processed signal and the second processed signal differ from each other by more than a predetermined amount, wherein the checker circuit comprises a first sample circuit configured to sample the first processed signal and generate a first sampled signal, a second sample circuit configured to process the second processed signal and generate a second sampled signal, and a window comparator responsive to the first sampled signal and the second sampled signal and configured to generate the fault signal.

7. The sensor integrated circuit of claim 6 further comprising:
at least one first magnetic field sensing element configured to sense a magnetic field and generate the first analog signal for coupling to the first processing channel; and
at least one second magnetic field sensing element configured to sense the magnetic field and generate the second analog signal for coupling to the second processing channel.

8. The sensor integrated circuit of claim 7 wherein the at least one first magnetic field sensing element and the at least one second magnetic field sensing element comprise different types of sensing elements.

9. The sensor integrated circuit of claim 8 wherein the different types of sensing elements comprise one or more of: a Hall effect element or a magnetoresistance element.

10. The sensor integrated circuit of claim 9 wherein the different types of sensing elements comprise one or more of a planar Hall effect element, a vertical Hall effect element, a circular vertical Hall effect element, Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance (AMR) element, a tunneling magnetoresistance (TMR) element or a magnetic tunnel junction (MTJ) element.

11. The sensor integrated circuit of claim 6 further comprising a sensing element configured to sense a parameter and generate both the first analog signal for coupling to the first processing circuit and the second analog signal for coupling to the second processing circuit.

12. The sensor integrated circuit of claim 11 wherein the sensing element comprises a resistor and the parameter comprises a current.

13. The sensor integrated circuit of claim 6 wherein the first processing channel comprises a first analog-to-digital converter configured convert the first analog signal into a first digital signal and the second processing channel comprises a second analog-to-digital converter configured to convert the second analog signal into a second digital signal.

14. The sensor integrated circuit of claim 13 wherein the first analog-to-digital converter has a first conversion accuracy and the second analog-to-digital converter has a second conversion accuracy different than the first conversion accuracy.

15. The sensor integrated circuit of claim 14 wherein the first analog-to-digital converter and the second analog-to-digital converter are different ones of a sigma-delta analog-to-digital converter, a dual slope analog-to-digital converter, and a successive approximation analog-to-digital converter.

16. The sensor integrated circuit of claim 6 wherein the sensor integrated circuit comprises an angle sensor and wherein the first processing channel comprises a zero crossing detector and the second processing channel comprises a CORDIC processor.

17. The sensor integrated circuit of claim 16 further comprising:
a circular vertical Hall element configured to sense a magnetic field and generate the first analog signal for coupling to the first processing channel; and
a pair of vertical Hall elements configured to sense the magnetic field and generate the second analog signal for coupling to the second processing channel.

18. The sensor integrated circuit of claim 6 wherein the sensor integrated circuit comprises a current sensor and wherein the first processing channel comprises a first analog filter having a first accuracy and the second processing channel comprises a second analog filter having a second accuracy different that the first accuracy.

19. The sensor integrated circuit of claim 18 wherein the first analog filter comprises a switched capacitor filter and the second analog filter comprises an RC filter.

20. The sensor integrated circuit of claim 6 further comprising:
a PWM generator responsive to the first processed signal to generate a PWM output signal having a duty cycle related to a level of the processed sign

Assignees

• Allegro Microsystems Llc

Inventors

• Haas David J
• Cesaretti Juan Manuel

Classifications

• G01R33/0023

  Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration (G01R33/0017 takes precedence) · CPC title

• H04L25/4902

  Pulse width modulation; Pulse position modulation · CPC title

• G01R31/2829

  Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844) · CPC title

• G01D3/08 Primary

  with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown · CPC title

• G08B21/182

  Level alarms, e.g. alarms responsive to variables exceeding a threshold · CPC title