Patent Issued for 1-Wire Communication Protocol and Interface Circuit

By a News Reporter-Staff News Editor at Journal of Engineering -- A patent by the inventors Lin, Allan Ming-Lun (Pleasanton, CA); Neyman, Leonid A. (Sunnyvale, CA), filed on January 29, 2010, was cleared and issued on December 4, 2012, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8324824 is assigned to IXYS Corporation (Milpitas, CA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Light-Emitting Diodes (LEDs) are being used increasingly in display devices, lighting applications, etc. For example, some modern liquid crystal display (LCD) devices use white LEDs as the backlight for the LCD display. These LEDs are typically driven by an LED driver that functions as a constant current device to supply a constant sink current fed through the LEDs to provide a constant luminescence or that functions as average current devices to supply a switching pulse width modulation sink current fed through the LEDs to provide a dimming luminescence. The amount of constant sink current driving the LEDs by the LED driver is typically controlled by a host controller residing in an electronic device (e.g., a mobile telephone, computer, etc.) that utilizes the LEDs.

"The host controller interfaces with the processor of the electronic device to receive pulse width modulation (PWM) commands directing the average intensity of illumination to be generated by the LED driver, and sends the PWM signals to the LED driver to adjust the average current for driving the LEDs. The host controller also communicates with the LED driver to send a variety of commands other than the PWM signals to the LED driver to program the LED driver, such as commands for setting the DC current to be provided by the LED driver to the LEDs.

"Conventional communication protocols and interface circuitry between a host controller and a LED driver require two separate communication channels (e.g., wires and IC pins) for communication of the PWM signals and the commands for programming the LED driver. Specifically, conventional 1-wire communication protocols are typically used by the host controller to communicate commands for programming the LED driver based on the number of pulses sent via the conventional 1-wire interface. All pulses sent over the conventional 1-wire interface are typically interpreted as commands. The conventional 1-wire communication protocols cannot be used for dynamic communication of PWM signals to adjust the average current for driving the LEDs. Thus, conventional LED drivers require an additional control pin on the LED driver integrated circuit (IC) to receive PWM pulses for adjusting the average LED drive current, in addition to the pin used by the 1-wire interface to receive commands from the host controller. This adds to the complexity and manufacturing cost of the LED driver and host controller ICs."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "According to various embodiments of the present invention, a 1-wire communication protocol and interface circuitry for communication between a host device (e.g., host controller) and a driver device (e.g., LED driver) is provided. The 1-wire communication protocol is configured such that both PWM signals and other commands (e.g., DC current setting commands) for programming the LED driver may be transmitted from the host controller to the LED driver via the same 1-wire interface. The 1-wire communication protocol uses the length of the pulses (i.e., pulse width), rather than the number of pulses, to distinguish between different modes of communication (PWM signal transmission mode or command pulse transmission mode) and different commands of the same type (specific DC current programming commands, or specific average PWM drive current for the LEDs, within each transmission mode). Because the same 1-wire interface is used for transmitting both PWM signals and programming commands for the LED driver, the same 1-wire interface may be used by the host controller and the LED driver for both DC current programming and PWM current adjustment without an additional wire or an additional pin on the host controller IC and the LED driver IC.

"In some embodiments, a communication system includes a host device and a driver device coupled to the host device via a 1-wire interface. The host device includes a first 1-wire interface controller and the driver device includes a second 1-wire interface controller. The second 1-wire interface controller communicates with the first 1-wire interface controller via a 1-wire communication protocol. Interface commands are transmitted from the host device to the driver device via the 1-wire interface and are decoded by the second 1-wire interface controller. The interface commands include PWM signals and command signals for programming the driver device. The 1-wire communication protocol transmits the PWM signals during PWM signal transmission mode and transmits the command signals during command signal transmission mode.

"In some embodiments, a communication system includes a host controller, an LED driver device coupled to the host controller via a 1-wire interface, and a plurality of LEDs coupled to the LED driver. The host controller includes a first 1-wire interface controller, and the LED driver includes a second 1-wire interface controller. The second 1-wire interface controller communicates with the first 1-wire interface controller via a 1-wire communication protocol. Interface commands are transmitted from the host controller to the LED driver via the 1-wire interface and are decoded by the second 1-wire interface controller. The interface commands include pulse width modulation (PWM) signals and command signals for programming the LED driver. The 1-wire communication protocol transmits the PWM signals during PWM signal transmission mode and transmits the command signals during command signal transmission mode. Each interface command comprises a preamble pulse, at least one command pulse and a post amble pulse. Each interface command begins with the preamble pulse and ends with the post amble pulse."

URL and more information on this patent, see: Lin, Allan Ming-Lun; Neyman, Leonid A.. 1-Wire Communication Protocol and Interface Circuit. U.S. Patent Number 8324824, filed January 29, 2010, and issued December 4, 2012. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=62&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=3052&f=G&l=50&co1=AND&d=PTXT&s1=20121204.PD.&OS=ISD/20121204&RS=ISD/20121204

Keywords for this news article include: IXYS Corporation.

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