Method for operating a magnetic field detector circuit and a magnetic field detector circuit

Patent metadata

Field	Value
Publication number	US-10018685-B2
Application number	US-201615366401-A
Country	US
Kind code	B2
Filing date	Dec 1, 2016
Priority date	Dec 1, 2015
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

A method is provided for operating a magnetic field detector circuit, whereby the magnetic field detector circuit is operated alternately in an active state or in a sleep state and the magnetic field detector circuit has a magnetic field measuring device and a wake-up timer, whereby the magnetic field measuring device comprises a magnetic field sensor. In the active state, the magnetic field measuring device is operated with a supply voltage and an output signal is generated by the magnetic field sensor. The magnetic field detector circuit comprises a wake-up timer, whereby the wake-up timer is operated with the supply voltage in the sleep state and a wake-up signal is generated by the wake-up timer after a predetermined sleep interval, and the magnetic field measuring device changes from the sleep state to the active state.

First claim

What is claimed is:

1. A method for operating a magnetic field detector circuit, the method comprising:
operating alternately the magnetic field detector circuit in an active state or in a sleep state, the magnetic field detector circuit having a magnetic field measuring device and a wake-up timer, the magnetic field measuring device having a magnetic field sensor;
operating, in the active state, the magnetic field measuring device with a supply voltage, an output signal being generated by the magnetic field sensor;
providing the magnetic field detector circuit with the wake-up timer that is operated with the supply voltage in the sleep state and a wake-up signal is generated by the wake-up timer after a predetermined sleep interval, the magnetic field measuring device changing from the sleep state to the active state based on the wake-up signal; and
providing the magnetic field detector circuit with a first predetermined threshold and a second predetermined threshold, the first predetermined threshold and the second predetermined threshold being voltage thresholds,
wherein the magnetic field measuring device changes to the sleep state when the output signal of the magnetic field sensor is below the second predetermined threshold, or
wherein the magnetic field measuring device changes to the active state when the output signal of the magnetic field sensor is above the first predetermined threshold.

2. The method according to claim 1 , wherein the magnetic field measuring device remains in the active state and a control signal is output, as long as the output signal of the magnetic field sensor in the first alternative is above the second predetermined threshold or in the second alternative below the first predetermined threshold.

3. The method according to claim 1 , wherein the predetermined sleep interval is 5 ms to 500 ms.

4. The method according to claim 1 , wherein the predetermined sleep interval is 50 ms to 100 ms.

5. The method according to claim 1 , wherein a duration of the wake-up signal is made shorter than a third or is made shorter than a tenth of a duration of the predetermined sleep interval.

6. The method according to claim 1 , wherein a control signal during the active state is applied to a control input of an output transistor unit, and wherein a resulting output of the output transistor unit is monitored based on a current during the active state.

7. The method according to claim 1 , wherein the first predetermined threshold is made greater than the second predetermined threshold.

8. The method according to claim 1 , wherein the magnetic field measuring device changes from the sleep state to the active state based on the wake-up signal, and remains in the active state based on the output of the magnetic field sensor.

9. A magnetic field detector circuit, the circuit comprising:
a magnetic field measuring device having an input for a supply voltage and being connected to a control input of an output transistor unit, the magnetic field measuring device being configured to output a control signal, the magnetic field measuring device having a magnetic field sensor;
a state control unit with an input for the supply voltage and an input for the control signal;
a wake-up timer having an output connected to the state control unit for a wake-up signal, the wake-up timer being connected to the supply voltage,
wherein the output of the state control unit is connected to the magnetic field measuring device,
wherein the state control unit has an output for a state signal formed depending on the control signal or depending on the wake-up signal,
wherein the state signal has a first value and a second value, and
wherein the magnetic field measuring device and the wake-up timer are controlled by the first and second values of the state signal,
wherein the magnetic field detector circuit operates the magnetic field measuring device in an active state or in a sleep state, the supply voltage being applied to the magnetic field measuring device only in the active state,
wherein the wake-up signal is generated by the wake-up timer after a predetermined sleep interval, the magnetic field measuring device changing from the sleep state to the active state based on the wake-up signal,
wherein the state control unit changes the magnetic field measuring device to the sleep state if an output signal of the magnetic field sensor is below a predetermined voltage threshold.

10. The magnetic field detector circuit according to claim 9 , wherein, when the first value is applied, the magnetic field measuring device enters the sleep state in order to apply the wake-up signal to the state control unit by the wake-up timer after a predetermined sleep interval, wherein the state signal assumes the second value upon application of the wake-up signal and changes the magnetic field measuring device to the active state upon application of the second value.

11. The magnetic field detector circuit according to claim 10 , wherein a short-circuit current monitoring unit is provided as part of the control unit to monitor a current of the output transistor during the active state.

12. The magnetic field detector circuit according to claim 9 , wherein the wake-up timer has a clock and a counter.

13. The magnetic field detector circuit according to claim 9 , wherein the magnetic field sensor of the magnetic field measuring device has at least one Hall element.

14. The magnetic field detector circuit according to claim 9 , wherein the magnetic field measuring device activates the control input of the output transistor unit by the control signal.

15. A magnetic field detector circuit, the circuit comprising:
a magnetic field measuring device with an input for a supply voltage and an output for a control signal, the output being connected to a control input of an output transistor unit, the magnetic field measuring device having a magnetic field sensor;
a state control unit with an input for the supply voltage, an input for the control signal, and an output for a state signal formed depending on the control signal; and
a state switch and a wake-up timer, the wake-up timer having an output for a wake-up signal and an input for the supply voltage, the state switch being arranged between the supply voltage input and the magnetic field measuring device and the wake-up timer,
wherein the state switch has an input for the state signal, and
wherein, based on the state signal, the magnetic field measuring device or the wake-up timer is supplied with the supply voltage by the state switch,
wherein the magnetic field detector circuit operates the magnetic field measuring device in an active state or in a sleep state, the supply voltage being applied to the magnetic field measuring device only in the active state,
wherein the wake-up signal is generated by the wake-up timer after a predetermined sleep interval, the magnetic field measuring device changing from the sleep state to the active state based on the wake-up signal,
wherein the state control unit changes the magnetic field measuring device to the sleep state if an output signal of the magnetic field sensor is below a predetermined voltage threshold.

Assignees

• Micronas Gmbh
• Tdk Micronas Gmbh

Inventors

• Kauter Thomas
• Muthers David
• Ritter Joachim

Classifications

• G01R33/07

  Hall effect devices · CPC title

• G01R33/0023 Primary

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