Atmel Corporation

Msilica, Incorporated

Kien Vi

Hendrik Santo

Dilip Sangam

Dilip S

Gurjit Thandi

Ranajit Ghoman

Matthew D Schindler

Zhiyu Yang

Tushar Heramb Dhayagude

Jeff Kotowski

Charles Cai

Timothy James Herklots

Ronald William Young

System(s) and method(s) are provided for power management in an electronic display via compensation of a power source of a light-emitting-diode (LED) backlighting system. A compensation feedback loop includes a load-aware controller that receives the bad condition from a dimming controller and supplies a control signal to the power source. An efficiency regulator functionally connected the backlight circuitry closes the compensation, feedback loop and provides an input signal to the load-aware controller. The dimming controller implements phase-shifted pulse-modulation dimming, which based on duty cycle can establish a dimming equilibrium with two load conditions. The load aware controller includes a set of compensation blocks arranged in parallel, with a single compensation block connected to the input signal and that provides the control signal. A selector component in the load aware controller determines a compensation block to be connected to the compensation feedback loop based on the received load condition.

Load-aware compensation in light-emitting-diode backlight illumination systems

A power conversion circuit of two feedback loops is disclosed that includes a feedback control circuit for ramping up or down a commanded voltage to a load (e.g., LEDs). The second feedback loop feeds into the first feedback loop, and the second feedback loop operates at a slower bandwidth than the first feedback loop. When ramping up or down the commanded voltage, a voltage overshoot results because of delay in the system. The overshoot can be compensated for by a final adjustment to the commanded voltage.

Power conversion feedback control circuit for reaching a goal voltage

System(s) and method(s) are provided for power management in an electronic display via compensation of a power source of a light-emitting-diode (LED) backlighting system. A compensation feedback loop includes a load-aware controller that receives the load condition from a dimming controller and supplies a control signal to the power source. An efficiency regulator functionally connected the backlight circuitry closes the compensation feedback loop and provides an input signal to the load-aware controller. The dimming controller implements phase-shifted pulse-modulation dimming, which based on duty cycle can establish a dimming equilibrium with two load conditions. The load aware controller includes a set of compensation blocks arranged in parallel, with a single compensation block connected to the input signal and that provides the control signal. A selector component in the load aware controller determines a compensation block to be connected to the compensation feedback loop based on the received load condition.

The present invention relates to circuits and methods for limiting the operating area of a transistor in a constant current source. The circuits and methods use a detector and a driver to limit the operating area of a transistor. The detector and driver have parameters selected so that, when the voltage at the drain of the transistor satisfies a reference condition, the driver causes drain current of the transistor to decrease. The reference condition is determined relative to the maximum safe drain-to-source voltage at the design drain current of the constant current source.

Method and circuit for an operating area limiter

The present invention involves an electrical system in which an analog signal channel passes through various integrated circuit chips (ICs). The channel can carry one or more analog signals. Each IC can modify the signal(s) passing through it and pass it on to another IC or system component. The channel can be programmable. Each IC can include a comparator or a multiplexor to receive the channel signal from another IC or system component and to modify the received signal before transmitting it to another IC or system component. The comparator or the multiplexor can be programmable and can be selectively configured to compare the incoming signal from the channel with a variety of other signals and thresholds, or to simply act as a flow through gate and allow the signal to pass without any modification. The comparison can determine the output of the comparator. The operation and programming of the comparators, the multiplexors and the channel can be centrally controlled by a system controller, can be independently controlled by the ICs, or a combination thereof.

Architecture and technique for inter-chip communication

The present invention relates to circuits and methods for detecting transistor operation in the triode region including a circuit for a transistor in a constant current source. The circuit comprises a detector having a first input, a second input, and an output. The first input of the detector is coupled to the source of the transistor and the second input of the detector is coupled to the set point terminal of the constant current source. The circuit also comprises a flag coupled to the detector output. The detector has parameters selected so that, when the voltage at the source of the transistor satisfies a reference condition, the output of the detector sets the flag. The reference condition is established relative to the voltage at the set point terminal of the constant current source and relative to the triode transition voltage of the transistor at a selected drain-source current.

Methods and circuits for triode region detection

System(s) and method(s) are provide to efficiently assess performance of a set of light emitting diode (LED) strings in an illumination system. A multiplexer component collects input signal from the one or more LED strings via a first set of one or more monitoring pins, processes the collected input signal, and extracts at least one output signal. The at least one output signal is conveyed to a demultiplexer component through a second set of one or more monitoring pins, wherein the number of elements in the second set of monitoring pins is equal to or smaller than the number of monitoring pins in the first set. The collected input signal is processed in accordance with at least one mode of operation of the multiplexer component, the mode of operation autonomously configured by the demultiplexer component. The multiplexer component can autonomously generate intelligence on operating status of the set of LED strings.

Smart monitoring of light emitting diode strings

The techniques of the present invention relate to automatically controlling display intensity. The present invention includes a calibration step in which the display intensity settings are correlated to the ambient light intensity conditions. The present invention also includes an automatic adjustment step in which the ambient light intensity is measured and the display intensity is automatically adjusted according to a correlation defined in the calibration step.

System and method for ambient-light adaptive intensity control for an electronic display

The present invention provides a controller for controlling strings of LEDs in a liquid crystal display. The hybrid controller uses both analog and digital circuit components. Error amplifiers are used to compare analog feedback signals received from the LED strings with reference signals. The results of those comparisons are converted to digital data and processed by a digital signal processor (DSP). The DSP calculates the drive voltages for the LED strings based on the deviation between the actual current flows (represented by feedback signals) and the desired current flows (represented by reference signals) through the LED strings. Analog drivers provide the drive voltages to the LED strings.

Hybrid analog and digital architecture for controlling backlight light emitting diodes of an electronic display

The present invention relates to displays that use LED strings for backlighting. A lead string is provided with continuous drive voltage and the non-lead strings are provided with pulsed drive pulses. The string having the highest forward voltage is selected as the lead string. Feedback information indicative of the currents flowing through the non-lead strings is used to determine the duty cycles of the voltage pulses provided to drive the non-lead strings. The non-lead strings are controlled using pulsed drive voltages to minimize power dissipation in the circuit.

System and method for controlling a multi-string light emitting diode backlighting system for an electronic display

The present invention provides a controller for regulating current in LEDs in electronic displays. The controller uses temperature sensing diodes to detect changes in the LED ambient temperature. As the LED ambient temperature changes, the forward voltage of the temperature sensing diode decreases. A signal processor adjusts the current passing through the LEDs based on the temperature induced changes in the forward voltage of the temperature sensing diodes. The present invention can reduce costs over the present methods of regulating current in LEDs and may more easily be integrated into a single integrated circuit chip. The temperature sensing may also be implemented outside the integrated circuit chip.

Temperature dependant LED current controller

The present invention uses two transistors instead of a sensing resistor to provide a constant current source for a load such as an array of light emitting diodes ('LEDs'). In the present invention, a bias current is applied to a branch of the circuit. The drain-to-source voltages of two transistors are matched. The voltage at the gate of both transistors is controlled based on the bias current and the drain-to-source current of the first of the two transistors. The second of the two transistors is sized such that source current of the second transistor is a multiple of the source current of the first transistor for a given gate voltage. By the techniques of this invention, the load current in a circuit is efficiently kept constant at a multiple of the input bias current.

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Palo Alto, CA, United States of America

Kien Vi