DC-DC converter with reduced electromagnetic interference
First Claim
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1. A DC-DC switching power supply, comprising:
- a power train;
a variable frequency oscillator generating a variable frequency output as a function of a pseudo random number and comprising;
a pseudo random number generator providing the pseudo random number; and
a digital to analog converter that takes the pseudo random number output by the pseudo random number generator and sets a current level as a function of the pseudo random number; and
a control system adapted to control the power train as a function of the variable frequency output of the variable frequency oscillator.
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Abstract
A DC-DC converter includes a variable frequency oscillator, a control system and a power train. The DC-DC converter is well suited for use in a cell phone. The control system uses the output of the oscillator to control the power train. The oscillator varies its frequency as a function of a pseudo random number generator, thereby reducing electromagnetic interference caused by ripple in the output of the DC-DC converter.
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14 Claims
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1. A DC-DC switching power supply, comprising:
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a power train; a variable frequency oscillator generating a variable frequency output as a function of a pseudo random number and comprising; a pseudo random number generator providing the pseudo random number; and a digital to analog converter that takes the pseudo random number output by the pseudo random number generator and sets a current level as a function of the pseudo random number; and a control system adapted to control the power train as a function of the variable frequency output of the variable frequency oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A DC-DC switching power supply, comprising:
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a power train; a variable frequency oscillator having an output and comprising; a pseudo random number generator; and a pair of digital to analog converters adapted to take a pseudo random number output by the pseudo random number generator and set a current level for charging and discharging a capacitor as a function of the pseudo random number; and a control system adapted to control the power train as a function of the output of the variable frequency oscillator.
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10. A method of operating a DC-DC converter comprising:
generating a variable frequency output with an oscillator as a function of a pseudo random number, generating the variable frequency output comprising; generating the pseudo random number with the pseudo random number generator; and providing the pseudo random number to a pair of digital to analog converters to set a current level used to charge and discharge a capacitor, thereby generating the variable frequency output as a function of the pseudo random number; and
controlling a power train as a function of the variable frequency output.- View Dependent Claims (11, 12, 13, 14)
Specification