Constant on-time converter with frequency control
AssigneeSilanna Asia Pte Ltd
InventorsRawinder Dharmalinggam, Tiong Lim
Life of this patent
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Abstract
An improved power converter produces power through a power switch in response to an activation signal that has an on-time and a switching frequency. An on-time signal has a constant on-time and controls the on-time of the activation signal. An error signal indicates that the switching frequency is not equal to a reference frequency. A step up signal and a step down signal are based on the error signal. A count signal is increased in response to the step up signal and decreased in response to the step down signal. An on-time pulse has a duration that is related to a value of the count signal. The on-time pulse controls the constant on-time of the on-time signal and maintains the switching frequency at about the reference frequency.
Claims20
A power converter comprising:
- an output at which an output voltage is produced;
- a power switch through which power is produced for the output voltage in response to an activation signal that has an on-time and a switching frequency;
- a constant on-time feedback loop receiving a feedback signal from the output and generating an on-time signal in response to the feedback signal, the on-time signal having a constant on-time and controlling the on-time of the activation signal;
- a frequency error detector producing an error signal indicating that the switching frequency is not equal to a reference frequency;
- a filter configured to produce a step up signal and a step down signal based on the error signal;
- a counter producing a count signal and configured to increase the count signal in response to the step up signal and to decrease the count signal in response to the step down signal;
- and
- a pulse generator producing an on-time pulse having a duration that is related to a value of the count signal, the pulse generator providing the on-time pulse to the constant on-time feedback loop to control the constant on-time of the on-time signal and to maintain the switching frequency at about the reference frequency.
A method comprising:
- generating an output voltage by a power switch of a power converter in response to an activation signal that has an on-time and a switching frequency;
- providing a feedback signal based on the output voltage;
- generating an on-time signal based on the feedback signal, the on-time signal having a constant on-time;
- controlling, based on the on-time signal, the on-time of the activation signal;
- producing an error signal indicative of whether the switching frequency is lower than or greater than a reference frequency;
- producing a step up signal and a step down signal based on the error signal;
- producing a count signal by increasing the count signal in response to the step up signal and decreasing the count signal in response to the step down signal;
- producing an on-time pulse having a duration that is related to a value of the count signal;
- and
- controlling, based on the on-time pulse, the constant on-time of the on-time signal, the controlling of the constant on-time resulting in maintaining the switching frequency at about the reference frequency.
Dependencies are inferred from the claim text.