Low cost LED driver with integral dimming capability
AssigneeAdvanced Analogic Technologies, Inc.
InventorsRichard K. Williams, Kevin D'Angelo, David A. Brown, George A. Hariman
Life of this patent
Estimating the term…
Abstract
A distributed system for driving strings of series-connected LEDs for backlighting, display and lighting applications includes multiple intelligent satellite LED driver ICs connected to a an interface IC via serial bus. The interface IC translates information obtained from a host microcontroller into instructions for the satellite LED driver ICs pertaining to such parameters as duty factor, current levels, phase delay and fault settings. Fault conditions in the LED driver ICs can be transmitted back to the interface IC. An analog current sense feedback system which also links the LED driver ICs determines the supply voltage for the LED strings.
Claims20
A method of controlling a plurality of light emitting diode (LED) strings by a plurality of LED driver integrated circuits, the method comprising:
- shifting digital data representative of a desired magnitude of current for each LED string of the plurality of LED strings into a shift register of each LED driver integrated circuit of the plurality of LED driver integrated circuits at a clock rate, each of the plurality of LED driver integrated circuits being serially connected together in a daisy chain;
- copying the digital data from the shift register of each LED driver integrated circuit at a frame rate, the clock rate being greater than the frame rate by a factor equal to at least a total number of bits of each shift register in each of the plurality of LED driver integrated circuits;
- and
- controlling a magnitude of current in each LED string based on the digital data.
A system for controlling a plurality of light emitting diode (LED) strings comprising:
- a plurality of LED driver integrated circuits, each of the plurality of the LED driver integrated circuits including a serial shift register to receive data representative of a desired magnitude of current in at least one LED string of the plurality of LED strings, each of the LED diver integrated circuits being constructed to copy the data representative of the desired magnitude of current from the shift register at a frame rate and control a magnitude of current in the at least one LED string based on the data representative of the desired magnitude of current;
- and
- a serial lighting interface bus, the serial lighting interface bus including the serial shift register in each of the plurality of LED driver integrated circuits connected in a daisy-chain, the serial shift register constructed to receive the data representative of the desired magnitude of current at a clock rate, the clock rate being greater than the frame rate by a factor equal to at least a total number of bits in the serial lighting interface bus.
Dependencies are inferred from the claim text.