Integrated magnetic field sensor and method of powering on and off a load

Patent metadata

Field	Value
Publication number	US-10088533-B2
Application number	US-201614993495-A
Country	US
Kind code	B2
Filing date	Jan 12, 2016
Priority date	Jan 14, 2015
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

An integrated magnetic field sensor includes a magnetic field sensing circuit and a power driving circuit disposed upon or within a common substrate. A method of powering on and off a load uses the above integrated magnetic field sensor.

First claim

What is claimed is:

1. An integrated magnetic field sensor comprising:
a semiconductor substrate disposed within an integrated circuit package, wherein the integrated circuit package comprises a thermal pad configured to thermally couple the substrate to a circuit board;
a magnetic field sensing circuit disposed upon or within the substrate and operable to generate a two-state signal responsive to a magnetic field; and
a power driving circuit disposed upon or within the substrate and operable to generate, in response to the two-state signal, a power driving signal having a higher power state and a lower power state.

2. The integrated magnetic field sensor of claim 1 , wherein the higher power state is operable to provide at least one hundred seventy milliamps of current.

3. The integrated magnetic field sensor of claim 2 , wherein the integrated magnetic field sensor is operable up to an environmental temperature of about one hundred twenty five degrees Celsius.

4. The integrated magnetic field sensor of claim 3 , wherein the power driving circuit comprises:
a temperature sensor disposed upon or within the substrate; and
a temperature compensation circuit responsive to the temperature sensor and operable to reduce the higher power state of the power driving signal to a reduced power state at environmental temperatures above a threshold temperature.

5. The integrated magnetic field sensor of claim 4 , wherein the threshold temperature is determined by a passive electronic component coupled to the integrated magnetic field sensor.

6. The integrated magnetic field sensor of claim 5 , wherein the threshold temperature comprises a plurality of threshold temperatures and wherein the temperature compensation circuit is operable to reduce the higher power state of the power driving signal to a corresponding plurality of different reduced power states at environmental temperatures above respective ones of the plurality of threshold temperatures.

7. The integrated magnetic field sensor of claim 5 , wherein the power driving circuit further comprises:
a slew limit circuit operable to limit a rate of change of the power driving signal between the higher power and lower power states.

8. The integrated magnetic field sensor of claim 5 , further comprising:
a permanent magnet coupled to the integrated circuit package for generating the magnetic field.

9. The integrated magnetic field sensor of claim 5 , wherein the integrated circuit package further comprises:
a conductor disposed upon or within the semiconductor substrate and proximate to the magnetic field sensing circuit, the conductor for generating the magnetic field.

10. The integrated magnetic field sensor of claim 1 , wherein the magnetic field sensing circuit comprises:
a magnetic field sensing element disposed upon the semiconductor substrate;
a conductor disposed upon the semiconductor and proximate to the magnetic field sensing element; and
a self-test circuit operable to drive a current into the conductor to generate a self-test of the integrated magnetic field sensor.

11. The integrated magnetic field sensor of claim 1 , wherein the magnetic field sensing circuit comprises:
a power on reset circuit operable to hold the two-state signal or to hold the power driving circuit into a condition to result in the lower power state for a predetermined time period following a time when power is applied to the integrated magnetic field sensor.

12. The integrated magnetic field sensor of claim 1 , wherein the higher power state is operable to provide at least one hundred seventy milliamps of current, wherein the magnetic field sensing circuit comprises a Hall effect element having first, second, third, and fourth electrical connection nodes disposed upon the semiconductor substrate, and wherein the power driving circuit is disposed upon the semiconductor substrate at a position to result in a predetermined thermal gradient direction at a position of the Hall effect element with respect to positions of the first, second, third, and fourth connections nodes.

13. The integrated magnetic field sensor of claim 1 , wherein the higher power state is operable to provide at least one hundred seventy milliamps of current, and wherein the magnetic field sensing circuit comprises a Hall effect element disposed upon the semiconductor substrate, and wherein the power driving circuit is disposed at a position upon the semiconductor substrate to result in a thermal gradient at a position of the Hall effect element smaller than one degree Celsius.

14. A method of powering on and off a load, comprising:
providing an integrated magnetic field sensor, the integrated magnetic field sensor comprising:
a semiconductor substrate disposed within an integrated circuit package, wherein the integrated circuit package comprises a thermal pad configured to thermally couple the substrate to a circuit board;
a magnetic field sensing circuit disposed upon or within the substrate and operable to generate a two-state signal responsive to a magnetic field; and
a power driving circuit disposed upon or within the substrate and operable to generate, in response to the two-state signal, a power driving signal having a higher power state and a lower power state, the method further comprising:

sensing a change of the magnetic field with the integrated magnetic field sensor, wherein the higher power state and the lower power state are achieved at different respective strengths or angles of the magnetic field.

15. The method of claim 14 , wherein the load is an automobile light.

16. The method of claim 15 , further comprising:
generating the magnetic field with a back-biasing magnet, the magnetic field influenced by a ferromagnetic object.

17. The method of claim 15 , wherein the higher power state is operable to provide at least one hundred seventy milliamps of current.

18. The method of claim 17 , wherein the integrated magnetic field sensor is operable up to an environmental temperature of about one hundred twenty five degrees Celsius.

19. The method of claim 18 , wherein the power driving circuit comprises:
a temperature sensor disposed upon or within the substrate; and
a temperature compensation circuit responsive to the temperature sensor and operable to reduce the higher power state of the power driving signal to a reduced power state at environmental temperatures above a threshold temperature.

20. The method of claim 19 , wherein the threshold temperature is determined by a passive electronic component coupled to the integrated magnetic field sensor.

21. The method of claim 20 , wherein the threshold temperature comprises a plurality of threshold temperatures and wherein the temperature compensation circuit is operable to reduce the higher power state of the power driving signal to a corresponding plurality of different reduced power states at environmental temperatures above respective ones of the plurality of threshold temperatures.

22. The method of claim 20 , wherein the power driving circuit further comprises:
a slew limit circuit operable to limit a rate of change of the power driving signal between the higher power and lower power states.

23. The method of claim 20 , further comprising:
generating the magnetic field with a permanent magnet.

24. The method of claim 20 , further comprising:
generating the magnetic field with a conductor.

25. The method of claim 14 , wherein t

Assignees

• Allegro Microsystems Llc
• Allegro Microsystems Inc

Inventors

• Rivas Manuel
• Monreal Gerardo A
• Graham Christine M
• Shoemaker Eric G

Classifications

• G01R33/07 Primary

  Hall effect devices · CPC title

• G01R33/007

  Environmental aspects, e.g. temperature variations, radiation, stray fields (G01R33/025 takes precedence) · CPC title

• G01R33/0082

  Compensation, e.g. compensating for temperature changes · CPC title

• B60Q3/30

  for compartments other than passenger or driving compartments, e.g. luggage or engine compartments · CPC title

• G05F3/08

  wherein the variable is DC · CPC title