Low noise fast dithering switching power supply
First Claim
1. A circuit comprising:
- switching circuitry adapted to;
receive a switching signal having a switching frequency;
transfer energy from a power source to an energy transfer circuit based on the switching signal; and
transfer energy from the energy transfer circuit to a load to create a load voltage, which has a first ripple voltage at the switching frequency and a second ripple voltage at a dithering frequency, based on the switching signal; and
control circuitry adapted to;
provide the switching signal to regulate the load voltage based on the power source and a setpoint; and
frequency-dither the switching frequency between a first frequency and a second frequency at the dithering frequency such that the second ripple voltage is approximately zero;
wherein the switching signal further comprises;
a first transitional period immediately following a period at the first frequency, and immediately preceding a period at the second frequency; and
a second transitional period immediately following a period at the second frequency, and immediately preceding a period at the first frequency wherein the first transitional period and the second transitional period compensate an inductor current such that an average inductor current remains substantially constant.
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Accused Products
Abstract
The present invention is a switching power supply that switches (dithers) between at least two switching frequencies without introducing a ripple signal at the dithering frequency, which is based on the time duration of a dithering cycle. In one embodiment of the present invention, an average current in an energy transfer element, such as an inductive element, during operation using one switching frequency is regulated to be approximately equal to the average current during operation using any other switching frequency. The average current may be regulated by controlling the durations of transition periods between operating using one switching frequency and operating using another switching frequency. By maintaining a constant average current while operating using different switching frequencies, dithering frequency ripple may be significantly reduced or eliminated.
9 Citations
24 Claims
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1. A circuit comprising:
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switching circuitry adapted to; receive a switching signal having a switching frequency; transfer energy from a power source to an energy transfer circuit based on the switching signal; and transfer energy from the energy transfer circuit to a load to create a load voltage, which has a first ripple voltage at the switching frequency and a second ripple voltage at a dithering frequency, based on the switching signal; and control circuitry adapted to; provide the switching signal to regulate the load voltage based on the power source and a setpoint; and frequency-dither the switching frequency between a first frequency and a second frequency at the dithering frequency such that the second ripple voltage is approximately zero; wherein the switching signal further comprises; a first transitional period immediately following a period at the first frequency, and immediately preceding a period at the second frequency; and a second transitional period immediately following a period at the second frequency, and immediately preceding a period at the first frequency wherein the first transitional period and the second transitional period compensate an inductor current such that an average inductor current remains substantially constant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method comprising:
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transferring energy based on a switching signal from a power source to a load, which has a first ripple voltage at a switching frequency and a second ripple voltage at a dithering frequency; and regulating power at the load based on the transferring and a setpoint; and frequency-dithering the switching frequency of the switching signal between a first frequency and at least one other frequency at the dithering frequency, such that the second ripple voltage is approximately zero; wherein the switching signal further comprises; a first transitional period immediately following a period at the first frequency, and immediately preceding a period at the second frequency; and a second transitional period immediately following a period at the second frequency, and immediately preceding a period at the first frequency wherein the first transitional period and the second transitional period compensate an inductor current such that an average inductor current remains substantially constant.
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Specification