Light emitting diode driver for dimming and on/off control

Patent metadata

Field	Value
Publication number	US-10219344-B2
Application number	US-201815957004-A
Country	US
Kind code	B2
Filing date	Apr 19, 2018
Priority date	Dec 14, 2016
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

In one aspect, an integrated circuit (IC) includes a first magnetic field sensor configured to sense a ring magnet, a second magnetic field sensor configured to sense the ring magnet and processing circuitry configured to receive a first signal from the first magnetic field sensor and to receive a second signal from the second magnetic field sensor. The processing circuitry is further configured to control an on/off state of at least one light emitting diode (LED) and brightness of the LED based on movement and position of the ring magnet with respect to the first and second magnetic field sensors.

First claim

What is claimed is:

1. An integrated circuit (IC) comprising:
a first magnetic field sensor configured to sense a magnet;
a second magnetic field sensor configured to sense the magnet; and
processing circuitry configured to:
receive a first signal from the first magnetic field sensor, wherein the first signal is based upon movement and position of the magnet with respect to the first magnetic field sensor;
receive a second signal from the second magnetic field sensor, wherein the second signal is based upon movement and position of the magnet with respect to the second magnetic field sensor; and
control an on/off state and brightness of a light emitting diode (LED) based on the received first and second signals.

2. The IC of claim 1 , wherein the processing circuitry is configured to hold the LED in an off state while the magnet is at a distance from the IC greater than a threshold distance.

3. The IC of claim 2 , wherein the LED is turned on when the magnet moves to a distance from the IC less than the threshold distance from the distance greater than the threshold distance.

4. The IC of claim 3 , wherein the processing circuitry is configured to hold the LED in an on state when the magnet returns to the distance from the IC greater than the threshold distance from the distance less than the threshold distance.

5. The IC of claim 4 , wherein the LED is turned off when the magnet moves to a distance from the IC less than the threshold distance from the returned to distance greater than the threshold distance.

6. The IC of claim 2 , wherein a waveform corresponding to an output waveform of the IC goes from low to high when the magnet moves to a distance from the IC less than the threshold distance from the distance greater than the threshold distance.

7. The IC of claim 1 , wherein the LED is turned on if the magnet is a first distance from the IC.

8. The IC of claim 7 , wherein the LED is turned off if the magnet is a second distance from the IC.

9. The IC of claim 1 , wherein the first magnetic field sensor and the second magnetic field sensor are both planar magnetic field sensors.

10. The IC of claim 9 , wherein at least one of the planar magnetic field sensors is a planar Hall element.

11. The IC of claim 1 , wherein the first magnetic field sensor and the second magnetic field sensor are both vertical magnetic field sensors.

12. The IC of claim 11 , wherein at least one of the vertical magnetic field sensors is at least one of vertical Hall element, a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance element (AMR) and a tunneling magnetoresistance (TMR) element.

13. The IC of claim 1 , wherein one of the first magnetic field sensor and the second magnetic field sensor is a vertical magnetic field sensor and the other one of the first magnetic field sensor and the second magnetic field sensor is a planar magnetic field sensor.

14. The IC of claim 13 , wherein the planar magnetic field sensor is a planar Hall element, and
wherein the vertical magnetic field sensor is at least one of vertical Hall element, a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance element (AMR) and a tunneling magnetoresistance (TMR) element.

15. The IC of claim 1 , further comprising a third magnetic field sensor configured to sense a magnet,
wherein processing circuitry is further configured to receive a third signal from the third magnetic field sensor and to control an on/off state of a light emitting diode (LED) and brightness of the LED based on movement and position of the magnet with respect to the first, second and third magnetic field sensors.

16. An integrated circuit (IC) comprising:
a first magnetic field sensor configured to sense a magnet;
a second magnetic field sensor configured to sense the magnet; and
processing circuitry configured to:
receive a first signal from the first magnetic field sensor, wherein the first signal changes in response to movement and position of the magnet with respect to the first magnetic field sensor;
receive a second signal from the second magnetic field sensor, wherein the second signal changes in response to movement and position of the magnet with respect to the second magnetic field sensor; and
control current to at least one light emitting diode (LED) based on the received first and second signals.

17. The IC of claim 16 , wherein the LED is off if the current supplied to the LED is zero.

18. The IC of claim 16 , wherein a waveform corresponding to an output waveform of the IC is low when the magnet is at a distance from the IC greater than a first threshold distance.

19. The IC of claim 18 , wherein the waveform is high when the magnet is at a distance from the IC less than a second threshold distance.

20. An integrated circuit (IC) comprising:
a first sensor means for sensing a magnet;
a second sensor means for sensing the magnet; and
processing means for controlling current to at least one light emitting diode (LED) in response to movement and position of the magnet with respect to the first and second sensor means, wherein the processing means is configured to hold the at least one LED in an off state while the magnet is at a distance from the IC greater than a threshold distance.

Assignees

• Allegro Microsystems Llc

Inventors

• Rivas Manuel
• Monreal Gerardo A

Classifications

• H05B45/10

  Controlling the intensity of the light · CPC title

• G01P13/04

  Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement · CPC title

• G01R33/077

  Vertical Hall-effect devices · CPC title

• G01D5/145

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title

• G01R33/093

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title