Power controllers and control methods for reducing output voltage ripple when line voltage is low
AssigneeLeadtrend Technology Corp.
InventorsFong Cheng Yang, Kuan Hsien Chou
Life of this patent
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Abstract
Disclosure includes a control method in use of a switching-mode power supply that supplies an output voltage to a load. A line voltage generated by rectifying an alternating-current voltage is detected to compare with a first reference voltage. A control signal is generated in response to the comparison of the line voltage and the first reference voltage. When the line voltage is less than the first reference voltage, the control signal is used to increase converted power that the switching-mode power supply provides to the output voltage. When the line voltage is not less than the first reference voltage, the control signal has no influence to the converted power.
Claims20
A control method in use of a switching-mode power supply to supply an output voltage to a load:
- detecting a line voltage generated by rectifying an alternating-current voltage;
- comparing the line voltage with a first reference voltage;
- and
- generating a control signal when the line voltage is less than the first reference voltage, in order to increase converted power that the switching-mode power supply provides to the output voltage;
- wherein the control signal is directly proportional to a difference between the first reference voltage and the line voltage when the line voltage is less than the first reference voltage.
A power controller in use of a switching-mode power supply for supplying an output voltage to a load, the power controller comprising:
- a feedback node, connected to an auxiliary winding via a resistor;
- and
- a low-line-voltage compensation circuit connected to the feedback node, for comparing a line voltage with a first reference voltage, and generating a control signal when the line voltage is less than the first reference voltage, to increase converted power that the switching-mode power supply provides to the output voltage;
- wherein the control signal is directly proportional to a difference between the first reference voltage and the line voltage when the line voltage is less than the first reference voltage.
A switching-mode power supply generating an output voltage to a load, the switching-mode power supply comprising:
- an inductive device comprising a primary winding, an auxiliary winding and a secondary winding;
- a power switch connected in series with the primary winding between a line voltage and an input ground;
- a power controller providing a PWM signal to control an ON time and an OFF time of the power switch, the power controller comprising:
- a feedback node coupled to the auxiliary winding, wherein the power controller detects the output voltage through the feedback node to generate a compensation signal;
- an ON-time controller controlling the ON time in response to the compensation signal;
- and
- a low-line-voltage compensation circuit, connected to the feedback node, for detecting the line voltage, comparing the line voltage with a first reference voltage, and generating a control signal when the line voltage is less than the first reference voltage, to increase converted power that the switching-mode power supply provides to the output voltage;
- wherein the control signal is directly proportional in proportion to a difference between the first reference voltage and the line voltage when the line voltage is less than the first reference voltage.
A switching-mode power supply generating an output voltage to a load, the switching-mode power supply comprising:
- an inductive device comprising a primary winding, an auxiliary winding and a secondary winding;
- a power switch connected in series with the primary winding between a line voltage and an input ground;
- a power controller providing a PWM signal to control an ON time and an OFF time of the power switch, the power controller comprising:
- a feedback node coupled to the auxiliary winding, wherein the power controller detects the output voltage through the feedback node to generate a compensation signal;
- an ON-time controller controlling the ON time in response to the compensation signal;
- and
- a low-line-voltage compensation circuit, connected to the feedback node, for detecting the line voltage, comparing the line voltage with a first reference voltage, and generating a control signal when the line voltage is less than the first reference voltage, to increase converted power that the switching-mode power supply provides to the output voltage;
- wherein the control signal is directly proportional to a difference between the first reference voltage and the line voltage when the line voltage is less than the first reference voltage.
Dependencies are inferred from the claim text.