Fairchild Semiconductor Corporation

Broadcom Corporation

James Zeng

Sridhar Kotikalapoodi

Lajos Burgyan

Rendon A Holloway

Farzan Roohparvar

Tivadar Szabo

Manisha P Pandyn

An LED driver circuit is disclosed that can drive a plurality of LED strings that are arranged in parallel, each LED string having a plurality of component LEDs that are series-connected. The LED strings can be the same type of LEDs in each string, or have different types of LEDs from one string to another. The LED driver includes a voltage control loop that dynamically regulates the output voltage across the parallel arrangement of LED strings. The output voltage is dynamically adjusted to accommodate the LED string with the largest operational voltage drop. This enables LED displays to constructed using different types of LEDs strings, but still supply the LED strings in a power efficient manner. Further, each LED string also includes its own individual current regulation loop so that the current, and therefore brightness, of each LED string can be individually adjusted.

Single inductor serial-parallel LED driver

A system and method providing output voltage control in a power supply circuit. Various aspects of the present invention may comprise at least a first module adapted to receive an input DC voltage and at least one voltage control signal and output an output DC voltage that is a function of the input DC voltage and the voltage control signal. At least a second module may be adapted to receive a feedback signal representative of the output DC voltage and output the at least one voltage control signal as a function of at least the feedback signal. The second module may, for example, be a digital module adapted to generate the at least one voltage control signal utilizing digital active components. The second module may also, for example, utilize transistors and/or passive components controlled by the digital active components to generate the at least one voltage control signal.

Voltage-locked loop

A power control circuit is provided containing a switch array, which includes segmented switches, a flying capacitor, an output voltage terminal, a feedback loop, and a digital voltage regulator block. The digital voltage regulator block includes an A/D converter, an encoder, an add-subtractor, and a gate logic. These power control circuits do not include pass transistors. A method is also provided, where the charge pumps of the power control circuit are operated in two-phase cycles including a charging phase and a pumping phase. The power control circuit is controlled in both of these phases, thereby reducing the ripple of the output voltage.

Digital loop for regulating DC/DC converter with segmented switching

A charge pumping system capable of a forward operation mode and a reverse operation mode is provided. In forward operation mode the charge pumping system can step-up an input voltage at a ratio of &#xbd;:1 and can step-down the input voltage at a ratio of n:m where n and m are both integer values and n is equal to or greater than m. In reverse operation mode the charge pumping system can step-down the input voltage at a ratio of 1:&#xbd; and 1:1 and can step-up the input voltage at a ratio of p:q where p and q are both integer values and p is less than q.

Charge pumping system and method

A charge pumping system capable of a forward operation mode and a reverse operation mode is provided. In forward operation mode the charge pumping system can step-up an input voltage at a ratio of &frac12;:1 and can step-down the input voltage at a ratio of at east one of 1:1, 3:2, 2:1 and 3:1. In reverse operation mode the charge pumping system can step-down the input voltage at a ratio of 1:&frac12;and 1:1 and can step-up the input voltage at a ratio of at least one of 2:3, 1:2 and 1:3.

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Cupertino, CA, United States of America

James Zeng