EP0469821A2
Expired / Lapsed
EP
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Switch mode power supply
Assignee: International Business Machines Corp
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Filing: 1991-07-29
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Granted: —
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Expires: 2011-07-29
Abstract
Abstract A switch mode power supply comprises a drive circuit (7) for generating first and second switching signals in response to first and second input signals of different frequencies, and a switching regulator (9) for generating one or more regulated power supply output voltages in response to the first and second switching signals. The power supply further comprises a control circuit (3,4,6,10,15) for determining, in response to the first and second input pulse signals, a first frequency range containing the frequencies of the first and second input signals when respectively multiplied by first and second integer multiples that is narrower than a second frequency range containing the frequencies of the first and second input signals when each multiplied by a common integer multiple. The control circuit (3,4,6,10,15) configures the drive circuit (7) to generate the first switching signal at a frequency which is the first integer multiple of the frequency of the first input pulse signal and the second switching signal at a frequency which is the second integer multiple of the frequency of the second input pulse signal in such a manner that the frequencies of the first and second switching signals are within the first range.
Inventors
- 👤 Masaki Kobayashi
- 👤 Masaki Mori
- 👤 Norishige Morimoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 12:45
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/18; H04N3/185; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/33507
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
202 words
A switch mode power supply comprising: a drive circuit (7) for generating first and second switching signals in response to, respectively, first and second input signals of different frequencies; and a switching regulator (9) for generating one or more regulated power supply output voltages in response to the first or the second switching signal; characterised in that the power supply further comprises a control circuit (3,4,6,10,15) for determining, in response to the first and second input signals, a first frequency range containing the frequencies of the first and second input signals when respectively multiplied by first and second integer multiples that is narrower than a second frequency range containing the frequencies of the first and second input signals when each input signal is multiplied by a common integer multiple, the control circuit (3,4,6,10,15) configuring the drive circuit (7) to generate the first switching signal at a frequency which is the first integer multiple of the frequency of the first input signal and the second switching signal at a frequency which is the second integer multiple of the frequency of the second input signal in such a manner that the frequencies of the first and second switching signals are within the first range.
Claim 2
Dependent Claim
91 words
A power supply as claimed in claim 1 wherein the control circuit (3,4,6,10,15) comprises: a control device (10) for initially configuring the control circuit (3,4,6,10,15) to determine the first and second integer multiples in response to the first and second input signals and for subsequently configuring the drive circuit to generate the first switching signal as a function of the first multiple in response to the first input signal and to generate the second second switching signal as a function of the second multiple in response to the second input signal.
Claim 3
Dependent Claim
84 words
A power supply as claimed in claim 2 wherein the control circuit (3,4,6,10,15) comprises: an oscillator circuit (3a) connected to the control device (10) for generating a sawtooth signal of one of a plurality of predetermined frequencies; and a synchronous circuit (3b) connected to the oscillator (3a) for configuring the drive circuit (7) to generate the first and second switching signals in response to the sawtooth signal and for synchronising the first and second switching signals to the first and second input signals respectively.
Claim 4
Dependent Claim
55 words
A power supply as claimed in claim 5 wherein the control circuit further comprises a switch (15) controlled by the control device (10) for initially connecting the output of the synchronous circuit (3b) to a frequency detecting circuit (4) and for subsequently connecting the output of the synchronous circuit (3b) to the drive circuit (7).
Claim 5
Dependent Claim
172 words
A power supply as claimed in claim 4 wherein the control circuit (3,4,6,10,15) comprises a frequency detecting circuit (4) connected to the control device (10) and a first register (6a) connected to the frequency detecting circuit (4), the control device being initially configured to determine a plurality of common integer multiples of the frequencies of the first and second input signals, to store the common integer multiples in the first register (6a), and to sweep the frequency of the sawtooth signal generated by the oscillator (3a) through a predetermined range of frequencies, the frequency detecting circuit (4) being configured to compare the sweeping frequency of the sawtooth signal with the common integer multiplies to detect a first plurality of frequency ranges for the sawtooth signal within which the synchronous circuit (4) can synchronise the first switching signal to the first input signal, and to detect a second plurality of frequency ranges for the sawtooth signal within which the synchronous circuit (4) can synchronise the second switching signal to the second input signal.
Claim 6
Dependent Claim
34 words
A power supply as claimed in claim 5 wherein the control circuit (4,6,10,15) comprises a second register (6b) connected to the control device (10) for storing the first and second pluralities of frequency ranges.
Claim 7
Dependent Claim
26 words
A display device comprising a switch mode power supply as claimed in any preceding claim, the first and second input signals being horizontal synchronisation pulse signals.
Claim 8
Independent Claim
173 words
A method of operating a switch mode power supply, the method comprising: generating first and second switching signals in response to first and second input signals of different frequencies; generating one or more regulated power supply output voltages in response to the first and second switching signals; determining, in response to the first and second input pulse signals, a first frequency range containing the frequencies of the first and second input signals when respectively multiplied by first and second integer multiples that is narrower than a second frequency range containing the frequencies of the first and second input signals when each multiplied by a common integer multiple; and generating the first switching signal at a frequency which is the first integer multiple of the frequency of the first input pulse signal and the second switching signal at a frequency which is the second integer multiple of the frequency of the second input pulse signal in such a manner that the frequencies of the first and second switching signals are within the first range.
References Cited (Backward Citations)
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