EMI REDUCTION OF POWER CONVERTERS BY WAY OF CONTROLLED RANDOMIZED MODULATION OF OSCILLATING SIGNALS
First Claim
1. A switching control circuit for generating a switch control signal for a switch of a power converter, the switch being operated so that the power converter produces reduced electromagnetic interference, the switching control circuit comprising:
- an output voltage monitor circuit configured to monitor the output voltage of the power converter, the output voltage monitor circuit producing an output voltage monitor signal;
a randomized signal generator configured to create a randomized signal;
a variable frequency oscillator configured to generate an oscillating signal, the frequency of the oscillating signal being based on a current state of a frequency modulation signal;
a frequency range converter configured to produce the frequency modulation signal, the current state of the frequency modulation signal being based upon a current state of the randomized signal, the frequency range converter limiting the current state of the frequency modulation signal so that the oscillating signal operates within a frequency range; and
a comparator configured to compare the voltage of the oscillating signal and the voltage of the output voltage monitor signal, the comparator producing the switch control signal.
1 Assignment
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Accused Products
Abstract
A switching control circuit for a switching power converter utilizes an oscillating signal that causes reduced electromagnetic interference by the power converter by way of modulating the frequency of the oscillating signal within a specified frequency range. An output voltage monitor circuit monitors the output voltage of the power converter, thus producing an output voltage monitor signal. Also, a randomized signal generator creates a randomized signal, which is then used to drive a frequency range converter that is employed to produce a frequency modulation signal. The current state of the frequency modulation signal is based on the current state of the randomized signal, with the frequency range converter limiting the current state of the frequency modulation signal so that the oscillating signal will only operate within the specified frequency range. A variable frequency oscillator then generates the oscillating signal whose frequency is based on the current state of the frequency modulation signal. A comparator then compares the oscillating signal with the output voltage monitor signal to produce a switch control signal, which is then employed to control a switching element of the power converter.
27 Citations
45 Claims
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1. A switching control circuit for generating a switch control signal for a switch of a power converter, the switch being operated so that the power converter produces reduced electromagnetic interference, the switching control circuit comprising:
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an output voltage monitor circuit configured to monitor the output voltage of the power converter, the output voltage monitor circuit producing an output voltage monitor signal;
a randomized signal generator configured to create a randomized signal;
a variable frequency oscillator configured to generate an oscillating signal, the frequency of the oscillating signal being based on a current state of a frequency modulation signal;
a frequency range converter configured to produce the frequency modulation signal, the current state of the frequency modulation signal being based upon a current state of the randomized signal, the frequency range converter limiting the current state of the frequency modulation signal so that the oscillating signal operates within a frequency range; and
a comparator configured to compare the voltage of the oscillating signal and the voltage of the output voltage monitor signal, the comparator producing the switch control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A switching control circuit for generating a switch control signal for a switch of a power converter, the switch being operated so that the power converter produces reduced electromagnetic interference, the switching control circuit comprising:
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means for monitoring the output voltage of the power converter, the monitoring means producing an output voltage monitor signal;
means for creating a randomized signal;
means for generating an oscillating signal, the frequency of the oscillating signal being based on a current state of a frequency modulation signal;
means for producing the frequency modulation signal, the current state of the frequency modulation signal being based upon a current state of the randomized signal, the producing means limiting the current state of the frequency modulation signal so that the oscillating signal operates within a frequency range; and
means for comparing the voltage of the oscillating signal and the voltage of the output voltage monitor signal, the comparing means producing the switch control signal. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A method for generating a switch control signal for a switch of a power converter, the switch being operated so that the power converter produces reduced electromagnetic interference, the method comprising:
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monitoring the output voltage of the power converter, the monitoring step producing an output voltage monitor signal;
creating a randomized signal;
generating an oscillating signal, the frequency of the oscillating signal being based on a current state of a frequency modulation signal;
producing the frequency modulation signal, the current state of the frequency modulation signal being based upon a current state of the randomized signal, the producing step limiting the current state of the frequency modulation signal so that the oscillating signal operates within a frequency range; and
comparing the voltage of the oscillating signal and the voltage of the output voltage monitor signal, the comparing step producing the switch control signal. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45)
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43. The power converter of claim 43, wherein the monitoring step comprises:
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dividing the output voltage of the DC/DC converter to produce a reduced output voltage signal; and
comparing the reduced output voltage signal with a DC voltage reference to produce the output voltage monitor signal.
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Specification