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Patent Issued for Switch Control Device, Multi-Channel Converter Including the Same, and Switch Controlling Method

September 10, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Yeon, Jae-Eul (Seoul, KR); Kang, Won-Seok (Chungbuk, KR), filed on March 14, 2011, was published online on August 26, 2014.

The assignee for this patent, patent number 8817502, is Fairchild Korea Semiconductor Ltd. (Bucheon, KR).

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to a switch control device, a multi-channel converter, and a switch control method, and particularly relates to a frequency modulation method. More particularly, the present invention relates to a switch control device using a multi-phase interleaving frequency modulation method, and a multi-channel converter and a switch control method thereof.

"In a case of an LLC resonant converter used as a power supply device of a display device such as PDP or LCD, it is not suitable for supplying a low voltage and a high current output power. In the LLC resonant converter, the high current load generates large current stress such that the output voltage may have a large ripple or the output capacitor may be heated. These problems reduce the life span of the converter.

"The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "The present invention reduces stress caused by the high current output from the converter, improves the life span of the converter, and improves the efficiency of the converter.

"A switch control device according to an exemplary embodiment of the present invention includes at least two converters having at least one power switch, and sums the output power of at least two converters to control a switching operation of a multi-channel converter supplied to a load. The switch control device includes a gate driver generating at least two gate signals for a switching operation of at least one power switch of two converters; and a multi-phase frequency modulation device modulating a switching frequency of at least one power switch according to the load, determining the number of phases of the multi-channel converter according to the load, and controlling the gate driver for a phase difference corresponding to the number of determined phases between at least two gate signals to be generated.

"The multi-phase frequency modulation device includes a frequency modulator generating a reference clock signal to modulate the switching frequency according to the load; a count generator determining the number of phases of the multi-channel converter according to the load, determining a reference clock number to count the number of determined phases, and counting the reference clock signals as a unit of the reference clock number to generate a count signal; and a count comparator comparing the count signal with at least two reference signals corresponding to the number of at least two converters to generate at least two comparison signals for generating the at least two gate signals.

"The count generator includes a phase management unit determining the reference clock number according to the load; and a MOD-n counter counting the reference clock signals to generate the count signal, wherein the phase management unit resets the MOD-n counter if the MOD-n counter counts the reference clock signals to the reference clock number.

"The phase management unit includes an error amplifier amplifying a difference between a predetermined reference voltage and the detecting voltage corresponding to the current flowing in the load to generate an error voltage; an AD convertor digital-converting the error voltage to generate the load detection signal; and a phase comparator determining the reference clock number according to the load detection signal, and resetting the MOD-n counter if the count signal arrives at the reference clock number.

"The counter generator includes a MOD-n counter reference counting the clock signals; and a phase management unit resetting the MOD-n counter after the MOD-n counter latches the count signal of the time counting the reference clock signal to a predetermined preset value.

"The phase management unit includes a comparator comparing the count signal and the preset value to determine whether the count signal arrives at the preset value; a phase latch latching the count signal if the count signal arrives at the preset value, and generating a clear signal to reset the MOD-n counter; and a delay unit transmitting the MOD-n counter after delaying the clear signal during a predetermined time.

"The count comparator includes at least two dividers dividing the latched count signal into the number of at least two converters, and multiplying the corresponding weight value among at least two weight values to generate the corresponding reference signal among two reference signals; and at least two comparators generating a comparison signal according to a comparison result of the corresponding reference signal and the count signal.

"The gate driver generates at least two gate signals according to at least two comparison signals.

"The frequency modulator includes an optocoupler through which the current corresponding to the output voltage of the multi-channel converter flows; a current mirror mirroring the current flowing in the optocoupler; a first dependant current source generating a first dependant current according to the mirrored current; a second dependant current source generating a second dependant current according to the mirrored current; a capacitor charged by the first dependant current and discharged by the second dependant current; a first comparator comparing the charged voltage to the capacitor and a predetermined first reference voltage; a second comparator comparing the charged voltage to the capacitor and a predetermined second reference voltage; and an SR flip-flop generating the edge of the reference clock signal according to the edge of the output signal of the first comparator, and generating the edge of the reference clock signal according to the edge of the output signal of the second comparator.

"The counter generator includes a phase control unit generating at least two phase control signals determining the number of phases of the multi-channel converter according to the load, and generates at least one compensation count signal according to the reference clock signal;

"The reference clock number is fixed according to the number of at least two converters, the at least one compensation count signal is a signal to control the operation of at least one converter among at least two converters when at least two converters all not operated; and

"The gate driver selects at least one of at least two comparison signals and at least one compensation count signal according to at least two phase control signals to generate at least one among at least two gate signals.

"The phase control unit detects the output current flowing in the load to generate a detecting voltage, and generates at least two phase control signals according to the comparison result of the predetermined first reference voltage and the predetermined second reference voltage.

"The count comparator includes at least two comparators generating at least two comparison signals according to the comparison result of the count signal and the corresponding reference signal; and a logic calculator inverting the output state in synchronization with one of the increasing and decreasing edges of the reference clock signal to generate a compensation clock signal, and inverting the output state in synchronization with one of the increasing and decreasing edges of the compensation clock signal generating at least one compensation count signal.

"The gate driver includes at least three multiplexers selecting and outputting one of at least two comparison signals and at least one compensation count signal according to at least two phase control signals.

"The multi-phase frequency modulation device includes a frequency modulator generating a reference clock signal to modulate the switching frequency according to the load; a phase control unit generating at least two phase control signals determining the number of phases of the multi-channel converter according to the load; and a count generator generating at least one compensation count signal according to the reference clock signal, and modulating the reference clock signal according to the number of at least two converters to generate at least two modulation clock signals, wherein at least one compensation count signal is a signal to control the operation of at least one converter among at least two converters when at least two converters are not operated, and the gate driver selects at least one of at least two modulation clock signals and at least one compensation count signal according to at least two phase control signals to generate at least one of at least two gate signals.

"The count generator includes at least two D-flip-flops of the same number as the number of at least two resonant converters, and the gate driver includes at least two multiplexers of the same number as the number of at least two resonant converters. Each clock terminal of at least two D-flip-flops is input with the reference clock signal, one output terminal of at least two D flip-flops is connected to the input terminal of a neighboring D flip-flop, at least two D-flip-flops respectively generate the corresponding modulation clock signal,

"Each output terminal of at least two D flip-flops is connected to the input terminal of the corresponding multiplexer among at least two multiplexers. At least two multiplexers respectively output the modulation clock signal of the corresponding D flip-flop according to at least two phase control signals.

"A switch control method according to the present invention is a method to control a switching operation of a multi-channel converter including at least two converters having at least one power switch, and supplying the sum of the output power of at least two converter to a load. The switch control method includes generating at least two gate signals for the switching operation of at least one power switch of at least two converters; modulating a switching frequency of at least one power switch according to the load; determining the number of phases of the multi-channel converter according to the load; and generating at least two gate signals to have a phase difference corresponding to the determined number of phases.

"The modulating of the switching frequency includes generating the reference clock signal for the modulation of the switching frequency according to the load, and the switch control method further comprises: determining a reference clock number to count the determined number of phases, and counting the reference clock signals according to the reference clock number; and comparing the counting result with at least two reference signals corresponding to the entire number of at least two converters to generate at least two comparison signals.

"The switch control method further includes resetting the counter result if the count result arrives at the reference clock number.

"The modulation of the switching frequency further includes generating at least one compensation count signal according to the reference clock signal, the determining of the number of phases of the multi-channel converter includes generating at least two phase control signals to determine the number of phases of the multi-channel converter according to the magnitude of the load, and the generating of the gate signal includes selecting at least one of at least two comparison signals and at least one compensation count signal according to at least two phase control signals to generate at least one among at least two gate signals.

"The generating of at least two phase control signals includes detecting the output current flowing in the load to generate a detecting voltage; generating one of at least two phase control signals according to the comparison result of a predetermined first reference voltage and the detecting voltage; and generating the other of at least two phase control signals according to the comparison result of a predetermined second reference voltage that is different from the first reference voltage and the detecting voltage.

"A multi-channel converter according to the present invention includes at least two converters including at least one power switch; an output capacitor connected to each output terminal of at least two converters; and a switch control device controlling the switching operation of at least one power switch, wherein the switch control device modulates a switching frequency of at least one power switch according to the load, determines the number of converters to be operated among at least two converters according to the load, and generates the phase difference corresponding to the number of determined converters between at least two gate signals for the switching operation of each of at least one power switch of at least two converters.

"The switch control device generates a reference clock signal of the load for the modulation of the switching frequency, determines a reference clock number to count the number of the determined converters, counts the reference clock signal as a unit of the reference clock number to generate the count signal, and compares the count signal and at least two reference signals corresponding to the number of at least two converters to generate at least two comparison signals to generate at least two gate signals.

"The switch control device generates a reference clock signal to modulate the switching frequency according to the load, counts the reference clock signals as a unit of the reference clock number corresponding to at least two converters to generate the count signal, and generates at least one compensation count signal according to the reference clock signal, and at least one compensation count signal is a signal to control the operation of at least one converter of at least two converters when at least two converters are not operated.

"As above described, the present invention provides a switch control device, a multi-channel converter including the same, and a switch control method.

"Accordingly, the converter according to the present invention is effective to a device requiring low voltage and high current."

For more information, see this patent: Yeon, Jae-Eul; Kang, Won-Seok. Switch Control Device, Multi-Channel Converter Including the Same, and Switch Controlling Method. U.S. Patent Number 8817502, filed March 14, 2011, and published online on August 26, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8817502.PN.&OS=PN/8817502RS=PN/8817502

Keywords for this news article include: Electronics, Fairchild Korea Semiconductor Ltd., Semiconductor.

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Source: Electronics Newsweekly


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