Control circuit and control method for switching regulator and switching regulator with the same
First Claim
1. A control circuit for a switching regulator having a first switch, the control circuit comprising:
- a) an ON signal generator configured to generate an ON signal;
b) an OFF signal generator configured to generate a first control signal according to an input voltage and an output voltage of said switching regulator, wherein said OFF signal generator comprises a first charge and discharge circuit comprising a first capacitor that is charged and discharged to generate a first voltage signal, and a comparator configured to compare said first voltage signal against a reference voltage to generate said first control signal, wherein said reference voltage is proportional to said output voltage;
c) an on time regulator configured to generate an adjustment signal according to a switching signal and said first control signal, wherein an on time of said first switch is controlled to be a constant on time when an off time of said first switch is greater than or equal to a reference time; and
d) a logic circuit configured to generate an off signal according to said first control signal, and to generate said switching signal according to said ON signal and said OFF signal, wherein said on time of said first switch is regulated according to said off time of said first switch when said off time of said first switch is less than said reference time, in order to regulate a duty cycle of said switching signal.
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Accused Products
Abstract
A control circuit for a switching regulator can include: an ON signal generator that generates an ON signal; an OFF signal generator that generates a first control signal according to an input voltage and an output voltage of the switching regulator; an on time regulator that generates an adjustment signal according to a switching signal and the first control signal; and a logic circuit configured to generate an off signal according to the first control signal, and to generate the switching signal according to the ON signal and the OFF signal, where the on time of the first switch is regulated according to the off time of the first switch when the off time of the first switch is less than the reference time, in order to regulate a duty cycle of the switching signal.
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Citations
17 Claims
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1. A control circuit for a switching regulator having a first switch, the control circuit comprising:
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a) an ON signal generator configured to generate an ON signal; b) an OFF signal generator configured to generate a first control signal according to an input voltage and an output voltage of said switching regulator, wherein said OFF signal generator comprises a first charge and discharge circuit comprising a first capacitor that is charged and discharged to generate a first voltage signal, and a comparator configured to compare said first voltage signal against a reference voltage to generate said first control signal, wherein said reference voltage is proportional to said output voltage; c) an on time regulator configured to generate an adjustment signal according to a switching signal and said first control signal, wherein an on time of said first switch is controlled to be a constant on time when an off time of said first switch is greater than or equal to a reference time; and d) a logic circuit configured to generate an off signal according to said first control signal, and to generate said switching signal according to said ON signal and said OFF signal, wherein said on time of said first switch is regulated according to said off time of said first switch when said off time of said first switch is less than said reference time, in order to regulate a duty cycle of said switching signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of controlling a switching regulator having a first switch, the method comprising:
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a) generating a switching signal comprising generating an ON signal in a ripple control mode, generating a first control signal according to an input voltage and an output voltage of said switching regulator, generating an OFF signal according to said first control signal, and generating said switching signal according to said ON signal and said OFF signal; b) said generating said first control signal comprising generating a first voltage signal by charging and discharging a first capacitor, generating said first control signal by comparing said first voltage signal against a reference voltage, and charging, by an adjustable first current and a constant second current, said first capacitor when said first control signal is inactive, and discharging said first capacitor when said first control signal is active, wherein said reference voltage is proportional to said output voltage, said first current is proportional to a high voltage, said second current is proportional to said input voltage, and said second current has an opposition direction to said first current; c) controlling the turn on and off of said first switch by said switching signal; d) comparing an off time of said first switch against a reference time, and generating an adjustment signal; e) controlling an on time of said first switch according to said adjustment signal; f) controlling, by said switching signal, said on time of said first switch to be a constant on time when said off time of said first switch is greater than or equal to said reference time; and g) regulating said on time of said first switch according to said off time of said first switch in order to regulate a duty cycle of said switching signal when said off time of said first switch is less than said reference time. - View Dependent Claims (14, 15, 16, 17)
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Specification