Serial lighting interface with embedded feedback
AssigneeAdvanced Analogic Technologies, Inc.
InventorsRichard K. Williams, Kevin D'Angelo, David A. Brown
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Abstract
A system for controlling multiple strings of LEDs includes a group of LED driver ICs, each of which includes a current sense feedback (CSFB) sample latch for storing a digital representation of the forward-voltage drop across a controlled LED string. Each CSFB latch is coupled to a register within a serial lighting interface (SLI) bus that both originates and terminates at an interface IC. As the data on the SLI bus is shifted into the interface IC, the interface IC selects the CSFB word that represents the highest forward-voltage drop of any of the controlled LED strings, which is then used by the interface IC to generate a CSFB signal for setting the appropriate supply voltage for the controlled LED strings.
Claims19
A method of generating a supply voltage for a plurality of light emitting diode (LED) strings comprising:
- detecting a highest forward-voltage of the plurality of LED strings;
- generating a digital current sense feedback (CSFB) word representing the highest forward-voltage;
- storing the digital CSFB word in a data register of a serial lighting interface (SLI) bus at a first rate;
- shifting the digital CSFB word along the SLI bus to an interface integrated circuit (IC) at a second rate, the second rate being greater than the first rate;
- and
- generating the supply voltage for the plurality of LED strings based on the digital CSFB word.
A light-emitting diode (LED) drive system comprising:
- a plurality of LED driver integrated circuits (ICs), each respective LED driver IC of the plurality of LED driver ICs including a terminal to connect to a first end of at least one LED string of a plurality of LED strings, each respective LED driver IC of the plurality of LED driver ICs being constructed to generate a digital current sense feedback (CSFB) value based on a voltage level at the terminal of the respective LED driver IC and store the digital CSFB value in a data register in the respective LED driver IC;
- a serial lighting interface (SLI) bus being constructed to serially shift data through the data register in each respective LED driver IC of the plurality of LED driver ICs;
- and
- an interface IC, coupled to the SLI bus, to receive the digital CSFB value from each respective LED driver IC of the plurality of LED driver ICs and identify a lowest digital CSFB value.
Dependencies are inferred from the claim text.