Single wire serial interface

• US 9,295,128 B2
• Filed: 09/16/2013
• Issued: 03/22/2016
• Est. Priority Date: 03/28/2002
• Status: Expired due to Fees

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: D'Angelo, Kevin P., Brown, David Alan, So, John Sung K., Nilsson, Jan, Williams, Richard K.
• Primary Examiner(s): Bae, Ji H
• Application Number:
  US14/028,365
• Publication Number:
  US 20140089722A1
• Time in Patent Office: 918 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 1/04 Generating or distributing clock signals or signals derived directly therefrom
• CPC Class Codes: G06F 1/06 Clock generators producing several clock signals G06F1/08 - G06F1/14 take precedence
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators
• CPC Class Codes: G06F 1/22 Means for limiting or controlling the pin/gate ratio
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: G06F 13/4291 using a clocked protocol
• CPC Class Codes: G06F 9/4403 Processor initialisation
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/397 Current mirror circuits

Abstract

A single wire serial interface for power ICs and other devices is provided. To use the interface, a device is configured to include an EN/SET input pin. A counter within the device counts clock pulses sent to the EN/SET input pin. The output of the counter is passed to a ROM or other decoder circuit. The ROM selects an operational state for the device that corresponds to the value of the counter. In this way, control states may be selected for the device by sending corresponding clock pulses to the EN/SET pin. Holding the EN/SET pin high causes the device to maintain its operational state. Holding the EN/SET pin low for a predetermined timeout period resets the counter and causes the device to adopt a predetermined configuration (such as off) until new clock pulses are received at the EN/SET pin.

Claims

1. A backlight driver, comprising:

circuitry configured to count pulses in a received signal to yield a count value, generate a control state for a light source in response to the pulses, generate an output that controls the light source in response to the control state, and reset the control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

2. The backlight driver of claim 1, wherein the count value comprises 32 levels.

3. The backlight driver of claim 1, wherein the output is transmitted on at least four current source pins.

4. The backlight driver of claim 1, wherein the circuitry comprises a read-only memory (ROM).

5. The backlight driver of claim 1, wherein the circuitry is further configured to maintain a control state in response to the received signal having a state that exceeds a second timeout duration, the second timeout duration being longer than a width of at least one of the pulses.

6. A method of controlling a light source, said method comprising the steps of:

receiving a signal;

counting pulses in the signal to yield a count value;

generating a control state for the light source in response to the pulses;

generating an output that controls the light source in response to the control state; and

resetting the control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

7. The method of claim 6, wherein the count value comprises 32 levels.

8. The method of claim 6, wherein the output is transmitted on at least four current source lines.

9. The method of claim 6, wherein the step of generating a control state comprises inputting the count value into a read-only memory (ROM).

10. A method of controlling a light source, said method comprising the steps of:

receiving a signal;

counting pulses in the signal to yield a count value;

generating a control state for the light source in response to the pulses;

generating an output that controls the light source in response to the control state; and

maintaining the control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

11. The method of claim 10, wherein the count value comprises 32 levels.

12. The method of claim 10, wherein the output is transmitted on at least four current source lines.

13. The method of claim 10, wherein the step of generating a control state comprises inputting the count value into a read-only memory (ROM).

14. A backlight driver, comprising:

circuitry configured to count pulses in a received signal to yield a count value, generate a control state for a light source in response to the pulses, generate an output that controls the brightness of the light source in response to the control state, and reset the control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

15. The backlight driver of claim 14, wherein the count value comprises 32 levels.

16. The backlight driver of claim 14, wherein the output is transmitted on at least four current source pins.

17. The backlight driver of claim 14, wherein the circuitry comprises a read-only memory (ROM).

18. The backlight driver of claim 14, wherein the circuitry is further configured to maintain a control state in response to the received signal having a state that exceeds a second timeout duration, the second timeout duration being longer than a width of at least one of the pulses.

19. A method of controlling the brightness of a light source, said method comprising the steps of:

counting pulses in a received signal to yield a count value;

generating a control state for a light source in response to the pulses;

generating an output that controls the brightness of the light source in response to the control state; and

resetting the control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

20. The method of claim 19, wherein the count value comprises 32 levels.

21. The method of claim 19, wherein the output is transmitted on at least four current source lines.

22. The method of claim 19, wherein the step of generating a control state comprises inputting the count value into a read-only memory (ROM).

23. A method of controlling the brightness of a light source, said method comprising the steps of:

counting pulses in a received signal to yield a count value;

generating a control state for a light source in response to the pulses;

generating an output that controls the brightness of the light source in response to the control state; and

maintaining the control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

24. The method of claim 23, wherein the count value comprises 32 levels.

25. The method of claim 23, wherein the output is transmitted on at least four current source lines.

26. The method of claim 23, wherein the step of generating a control state comprises inputting the count value into a read-only memory (ROM).

27. A backlight driver, comprising:

circuitry configured to progressively select control states based on the pulses received at an input, generate an output that controls the brightness of the light source in response to the control states, and reset an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

28. The backlight driver of claim 27, the circuitry further configured to progressively increase the brightness of the light source in response to the control states.

29. The backlight driver of claim 27, wherein the circuitry is further configured to maintain a control state in response to the received signal having a state that exceeds a second timeout duration, the second timeout duration being longer than a width of at least one of the pulses.

30. A method of driving a light source, said method comprising the steps of:

progressively selecting control states based on pulses received in an input signal;

generating an output that controls the brightness of the light source in response to the control states; and

resetting an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

31. The method of claim 30, further comprising progressively increasing the brightness of the light source in response to the control states.

32. A method of driving a light source, said method comprising the steps of:

progressively selecting control states based on pulses received in an input signal;

generating an output that controls the brightness of the light source in response to the control states; and

maintaining an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

33. The method of claim 32, further comprising progressively increasing the brightness of the light source in response to the control states.

34. A backlight driver, comprising:

light source control circuitry in communication with an input, the light source control circuitry configured to count pulses to yield a count value and to progressively select a plurality of control states until a desired control state is reached, generate a control state in response to the pluses, and generate a boosted-output in response to the control state, the boosted-output configured to control brightness of the plurality of light emitting diodes (LEDs); and

an output pin in communication with the LED driver circuit and configured to output the boosted-output for the plurality of LEDs.

35. The backlight driver of claim 34, wherein the count value comprises 32 levels.

36. The backlight driver of claim 34, wherein the circuitry is further configured to reset an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

37. The backlight driver of claim 34, wherein the circuitry is further configured to maintain a control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

38. A method of driving a plurality of light emitting diodes (LEDs), said method comprising the steps of:

receiving an input;

counting pulses in the input to yield a count value and to progressively select a plurality of control states until a desired control state is reached;

generating a control state in response to the pluses;

generating a boosted-output in response to the control state, the boosted-output configured to control brightness of the plurality of LEDs; and

outputting the boosted-output to the plurality of LEDs.

39. The method of claim 38, wherein the count value comprises 32 levels.

40. The method of claim 38, further comprising the step of resetting an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

41. The method of claim 38, further comprising the step of maintaining a control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

42. A backlight driver, comprising:

an input pin configured to be able to receive power from a power source;

light emitting diode (LED) driver circuitry in communication with the input pin and configured to drive a plurality of LEDs, the LED driver circuitry configured to count pulses, generate a control state in response to the pulses, and generate a boosted-output in response to the control state, the boosted-output configured to control brightness of the plurality of LEDs; and

an output pin in communication with the LED driver circuit and configured to output the boosted-output for the plurality of LEDs.

43. The backlight driver of claim 42, wherein the circuitry is further configured to reset an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

44. The backlight driver of claim 42, wherein the circuitry is further configured to maintain a control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

45. A method of driving a light source, said method comprising the steps of:

receiving power, by an input pin, from a power source;

communicating, by light emitting diode (LED) driver circuitry, with the input pin;

counting pulses, by the LED driver circuitry;

generating a control state in response to the pulses;

generating a boosted-output in response to the control state;

controlling brightness of the plurality of LEDs using the boosted-output; and

outputting the boosted-output to the plurality of LEDs using an output pin.

46. The method of claim 45, further comprising the step of resetting an existing control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.

47. The method of claim 45, further comprising the step of maintaining a control state in response to the received signal having a state that exceeds a timeout duration, the timeout duration being longer than a width of at least one of the pulses.