Method for controlling the output voltage of a DC-DC converter
First Claim
1. A method for controlling the output voltage of a DC--DC converter, comprising the steps of:
- generating an error output signal indicating the voltage difference between the output voltage the DC--DC converter and a reference voltage;
generating a comparison signal by comparing the voltage difference and a predetermined offset voltage, wherein the comparison signal having a predetermined level is generated when the voltage difference is equal to or greater than the predetermined offset voltage;
generating a triangular wave signal;
generating a duty control signal having a predetermined duty ratio by comparing the triangular wave signal and one of the error output signal and the comparison signal, wherein the duty control signal having the maximum duty ratio and the comparison signal having a predetermined level are generated substantially simultaneously; and
generating the output voltage by causing an output transistor to turn on or off in response to the duty control signal, wherein the output transistor is turned on while the duty control signal having the maximum duty ratio is being supplied to the output transistor.
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Accused Products
Abstract
A DC--DC converter includes an offset comparator that compares an output voltage with a reference voltage in parallel with an error amplification circuit, which also compares the output voltage with the reference voltage. The offset comparator has a predetermined offset voltage set between its input terminals so that the offset comparator outputs a high signal when the voltage difference between its inputs exceeds the predetermined level. The output of the offset comparator is input, along with the error amplification circuit output, into a PWM comparator. The signal output by the offset voltage comparator allows the DC--DC converter to more quickly respond to a sudden increase in current consumption by a connected load. In responding to the increased current draw, the DC--DC converter quickly converges back at the reference voltage, such that the DC--DC converter provides a very stable output voltage.
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Citations
29 Claims
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1. A method for controlling the output voltage of a DC--DC converter, comprising the steps of:
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generating an error output signal indicating the voltage difference between the output voltage the DC--DC converter and a reference voltage; generating a comparison signal by comparing the voltage difference and a predetermined offset voltage, wherein the comparison signal having a predetermined level is generated when the voltage difference is equal to or greater than the predetermined offset voltage; generating a triangular wave signal; generating a duty control signal having a predetermined duty ratio by comparing the triangular wave signal and one of the error output signal and the comparison signal, wherein the duty control signal having the maximum duty ratio and the comparison signal having a predetermined level are generated substantially simultaneously; and generating the output voltage by causing an output transistor to turn on or off in response to the duty control signal, wherein the output transistor is turned on while the duty control signal having the maximum duty ratio is being supplied to the output transistor.
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2. A method for controlling the output voltage of a DC--DC converter, comprising the steps of:
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generating an error output signal indicating the voltage difference between the output voltage of the DC--DC converter and a reference voltage; generating a triangular wave signal; generating a duty control signal having a predetermined duty ratio by comparing the error output signal and the triangular wave signal; generating a comparison signal by comparing the voltage difference between the output voltage and the reference voltage and a predetermined offset voltage, wherein the comparison signal having a predetermined level is generated when the voltage difference is equal to or greater than the predetermined offset voltage; and generating the output voltage by causing an output transistor to turn on or off in response to the duty control signal, wherein the comparison signal is supplied to the output transistor instead of the duty control signal to cause the output transistor to be turned on.
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3. A control circuit for controlling the output voltage of a DC--DC converter by controlling a first output transistor of the DC--DC converter, comprising:
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an error amplification circuit for comparing the output voltage of the DC--DC converter and a reference voltage and generating an error output signal indicating the voltage difference between the output voltage of the DC--DC converter and the reference voltage; an offset comparator for comparing a predetermined offset voltage and the error output signal and generating a comparison signal, wherein the comparison signal has a predetermined level when the error output signal is equal to or greater than the predetermined offset voltage; a triangular wave oscillation circuit for generating a triangular wave signal; and a first PWM comparator, connected to the error amplification circuit, the offset comparator, and the triangular oscillation circuit, for comparing the triangular wave signal and one of the error output signal and the comparison signal, generating a first duty control signal having a predetermined duty ratio and supplying the first duty control signal to the first output transistor, wherein the first duty control signal has a maximum duty ratio which turns on the first output transistor when the comparison signal having the predetermined level is supplied from the offset comparator to the first PWM comparator. - View Dependent Claims (4, 5, 6)
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7. A control circuit for controlling the output voltage of a DC--DC converter by controlling a first output transistor of the DC--DC converter, comprising:
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an error amplification circuit for comparing the output voltage of the DC--DC converter and a reference voltage and generating the error output signal indicating the voltage difference between the output voltage of the DC--DC converter and the reference voltage; an offset comparator for comparing a predetermined offset voltage and the error output signal and generating a comparison signal, wherein the comparison signal has a predetermined level when the error signal is equal to or greater than the predetermined offset voltage; and a triangular wave oscillation circuit for generating a triangular wave signal; a first PWM comparator, connected to the error amplification circuit and the triangular oscillation circuit, for comparing the error output signal and the triangular wave signal and supplying a first duty control signal having a predetermined duty ratio; and a selection circuit, connected to the offset comparator and the first PWM comparator, for selecting one of the comparison signal and the first duty control signal and supplying the selected signal to the first output transistor, wherein the selection circuit supplies the comparison signal to the first output transistor to turn on the first output transistor when the comparison signal having the predetermined level is generated. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A DC--DC converter for generating an output voltage, comprising:
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a smoothing circuit; a first output transistor, connected to the smoothing circuit, for generating the output voltage; an error amplification circuit for comparing the output voltage and a reference voltage and generating an error output signal indicating the voltage difference between the output voltage and the reference voltage; an offset comparator for comparing a predetermined offset voltage and the error output signal and generating a comparison signal, wherein the comparison signal has a predetermined level when the error output signal is equal to or greater than the predetermined offset voltage; a triangular wave oscillation circuit for generating a triangular wave signal; and a first PWM comparator, connected to the error amplification circuit, the offset comparator, and the triangular oscillation circuit, for comparing the triangular wave signal and one of the error output signal and the comparison signal, generating a first duty control signal having a predetermined duty ratio and supplying the first duty control signal to the first output transistor, wherein the first duty control signal has a maximum duty ratio which turns on the first output transistor when the comparison signal having the predetermined level is supplied from the offset comparator to the first PWM comparator. - View Dependent Claims (14, 15, 16)
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17. A DC--DC converter for generating an output voltage, comprising:
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a smoothing circuit; a first output transistor, connected to the smoothing circuits, for generating the output voltage; an error amplification circuit for comparing the output voltage and a reference voltage and generating an error output signal indicating the voltage difference between the output voltage of the DC--DC converter and the reference voltage; an offset comparator for comparing a predetermined offset voltage and the error output signal and generating a comparison signal, wherein the comparison signal has a predetermined level when the error signal is equal to or greater than the predetermined offset voltage; and a triangular wave oscillation circuit for generating a triangular wave signal; a first PWM comparator, connected to the error amplification circuit and the triangular oscillation circuit, for comparing the error output signal and the triangular wave signal and supplying a first duty control signal having a predetermined duty ratio; and a selection circuit, connected to the offset comparator and the first PWM comparator, for selecting one of the comparison signal and the first duty control signal and supplying the selected signal to the first output transistor, wherein the selection circuit supplies the comparison signal to the first output transistor to turn on the first output transistor during the time when the comparison signal having the predetermined level is generated. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A control circuit for controlling the output voltage of a DC--DC converter, comprising:
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an error amplification circuit having an inverting input terminal that receives the output voltage of the DC--DC converter and a noninverting input terminal that receives a reference voltage, the error amplification circuit comparing the output voltage and the reference voltage and generating an error amplification signal; an offset comparator having an inverting input terminal that receives the output voltage of the DC--DC converter and a noninverting input terminal that receives the reference voltage, the offset comparator comparing the output voltage and the reference voltage and generating a comparison signal, wherein when the output voltage is less than the reference voltage by more than a predetermined offset voltage value, the comparison signal has a high value; a triangular wave oscillation circuit for generating a triangle wave signal; and a first PWM comparator having a first noninverting input terminal connected to the error amplification circuit and receiving the error output signal, a second noninverting input terminal connected to the offset comparator and receiving the comparison signal, an inverting input terminal connected to the triangular wave oscillation circuit and receiving the triangle wave signal, and an output terminal connected to an output transistor of the DC--DC converter, the first PWM comparator comparing the triangle wave signal to the larger one of the error output signal and the comparison signal, and generating a first duty control signal therefrom, wherein the first duty control signal has a maximum duty ratio which turns on the output transistor when the comparison signal has the high value. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification