Catalyst Semiconductor, Inc.

Semiconductor Components Industries, LLC

Chris B Bartholomeusz

Anthony Gerard Russell

Sorin Stefan Georgescu

A charge pump provides a programmable multiplication factor for generating an output voltage. A first output voltage may be generated by connecting a first plurality of N capacitors in a first plurality of (N+1) configurations. A second output voltage may be generated by connecting a second plurality of M capacitors in a second plurality of M+1 configurations. The first plurality of N capacitors and the second plurality of M capacitors have one or more capacitors in common. The integers M and N may be equal, although this is not required. The first plurality of configurations is different than the second plurality of configurations, thereby providing different multiplication factors for the first and second pluralities of configurations. In one embodiment, the first plurality of (N+1) configurations results in an output voltage of about 3/4&#xd7; an input voltage.

Programmable fractional charge pump for DC-DC converter

A charge pump provides a multiplication factor of &#x2154; by using a three-phase mode of operation. In a first mode, first and second capacitors are charged from an input voltage while a third capacitor drives the output voltage based on stored charge in the third capacitor. In a second mode, the output terminal is connected to the common node of the first and second capacitors. In a third mode, the voltage potential across the second capacitor is subtracted from the sum of the input voltage and the voltage potential across the first capacitor to generate the output voltage. Operated in this manner, the first, second, and third capacitors will provide the desired &#x2154;&#xd7; voltage multiplication. This relatively low multiplication factor can be beneficial in applications requiring 2.5V and 1.8V supplies for integrated circuits, particularly where the input voltage is provided by a lithium battery.

Fractional charge pump for step-down DC-DC converter

A step down switching regulator circuit that is particularly well-suited to drive high power LEDs includes a crossover conduction mode (XCM) control circuit that maintains operation at the crossover point between continuous conduction mode (CCM) and discontinuous conduction mode (DCM). This XCM operation provides an inductor current waveform that ramps up and down between zero and a desired maximum current. One or more comparators in the XCM control circuit can be used to control switching between the inductor current ramp up and ramp down phases. In this manner, complex feedback loop logic and PID controlled PWM signal generation logic can be avoided, and the need for external sense resistors and associated interface pins can be eliminated.

LED current bias control using a step down regulator

A charge pump provides a multiplication factor of 4/3 by using a three-phase mode of operation. In a first mode, first and second capacitors are charged from an input voltage while a third capacitor drives the output voltage based on stored charge in the third capacitor. In a second mode, the voltage potential across the first capacitor is added to the input voltage to generate the output voltage. In a third mode, the voltage potential across the first capacitor is subtracted from the sum of the input voltage and the voltage potential across the second capacitor to generate the output voltage. Operated in this manner, the first, second, and third capacitors will provide the desired 4/3&#xd7; voltage multiplication. This relatively low multiplication factor can be beneficial in applications such as white LED driver circuits, particularly where the input voltage is provided by a battery.

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Santa Clara, CA, United States of America

Chris B Bartholomeusz