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US 8,576,583 B2Granted
Sampled charge control for resonant converter
AssigneeFairchild Semiconductor Corporation
InventorHangseok Choi
Life of this patent
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Abstract
This document discusses, among other things, apparatus and methods for controlling a converter. In an example, a voltage-controlled oscillator (VCO) can be configured to provide a first pulse train to control the converter. The frequency of the first pulse train of the VCO can be modulated using information indicative of an operating condition of the converter to maintain a desired DC voltage at an output. In an example, the VCO can include a frequency divider configured to provide a second pulse train to the output using information from the first pulse train.
Claims20
An apparatus to control a converter, the apparatus comprising:
- a first input configured to receive first information indicative of an operating condition of the converter;
- an output configured to couple to a switch of the converter;
- a voltage-controlled oscillator (VCO) configured to provide a first pulse train having a first frequency, and to modulate the first frequency responsive to the first information;
- a frequency divider configured to provide a second pulse train to the output, the second pulse train having a second frequency lower than the first frequency;
- wherein the VCO includes a threshold comparator to generate the first pulse train;
- and
- wherein the VCO is configured to adjust a threshold input of the threshold comparator in response to the first information.
4 more elements
A method to control a converter, the method comprising:
- receiving first information indicative of an operating condition of the converter;
- providing a first pulse train having a first frequency using a voltage-controlled oscillator (VCO);
- modulating the first frequency in response to the received information;
- providing a second pulse train to an output coupled to a switch of the converter;
- adjusting a second frequency of the second pulse train using the first pulse train and a frequency divider;
- wherein the receiving first information includes sensing a voltage indicative of current flow through a primary winding of a transformer of the converter while the switch is conducting;
- and
- wherein the sensing a voltage indicative of current flow includes:
- sensing a resistor voltage indicative of current flow through the primary winding;
- generating a current proportional to the resistor voltage;
- charging a feedback capacitor using the proportional current;
- sampling and holding a value of a voltage of the feedback capacitor when a second switch of the converter is conducting;
- and
- processing the sampled value with a threshold reference value to set a threshold of the VCO.
11 more elements
A system comprising:
- a converter including:
- a transformer;
- first and second switches coupled to the transformer, the first and second switches configured to provide a first alternating current (AC) signal to a primary winding of the transformer;
- and
- an output rectifier configured to rectify a second alternating signal from a secondary winding of the transformer to generate a direct current (DC) voltage at an output of the converter;
- a controller coupled to control inputs of the first and second switches, the controller configured to switch the first and second switches in a complementary fashion to generate the first AC signal, wherein the controller includes
- a voltage-controlled oscillator (VCO) configured to provide a first pulse train at a first frequency and a second pulse train at a second frequency to control the switching of the first and second switches;
- wherein the second frequency is about half of the first frequency to equalize a duty cycle of the first and second switches;
- wherein the VCO includes a threshold comparator to generate the first pulse train;
- and
- wherein the VCO is configured to adjust a threshold input of the threshold comparator in response to the first information;
- and
- a first sensor circuit configured to sense an operating condition of the converter and to adjust the first frequency of the VCO each switch cycle of the first switch in response to the sensed operating condition to maintain a desired DC voltage at the output of the converter.
10 more elements
Dependencies are inferred from the claim text.