Flyback power supply circuit with programmable function and control method thereof
First Claim
1. A flyback power supply circuit with a programmable function, comprising:
- a transformer circuit, which includes;
a primary winding, for receiving an input voltage;
a secondary winding, for generating a programmable output voltage at an output node; and
a tertiary winding, for generating a feedback signal related to the programmable output voltage according to the programmable output voltage;
a power switch circuit, which is coupled to the primary winding, for operating a power switch therein according to an operation signal, so as to convert the input voltage to the programmable output voltage;
a primary side control circuit, which is coupled to the power switch circuit, for generating the operation signal according to a target control signal;
an opto-coupler circuit, which is coupled to the secondary winding, for generating the target control signal according to the programmable output voltage and a programming signal; and
a secondary side control circuit, which is coupled to the opto-coupler circuit and the secondary winding, for generating the programming signal according to the programmable output voltage and a setting signal;
wherein the primary side control circuit determines whether an over voltage condition occurs according to a rate of increase of the feedback signal and a control level of the target control signal, or according to the rate of increase of the feedback signal and a rate of change of the target control signal, and the primary side control circuit generates an over voltage protection signal when the over voltage condition occurs.
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Accused Products
Abstract
The present invention discloses a flyback power supply circuit with a programmable function and a control method thereof. The flyback power supply circuit includes: a transformer circuit, a power switch circuit, a primary side control circuit, an opto-coupler circuit, and a secondary side control circuit. The primary side control circuit determines whether an over voltage condition occurs, and further determines whether to generate an over voltage protection signal to turn OFF a power switch of the power switch circuit according to a rate of increase of a feedback signal and a control level, or according to the rate of increase of the feedback signal and a rate of change of a target control signal.
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Citations
23 Claims
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1. A flyback power supply circuit with a programmable function, comprising:
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a transformer circuit, which includes; a primary winding, for receiving an input voltage; a secondary winding, for generating a programmable output voltage at an output node; and a tertiary winding, for generating a feedback signal related to the programmable output voltage according to the programmable output voltage; a power switch circuit, which is coupled to the primary winding, for operating a power switch therein according to an operation signal, so as to convert the input voltage to the programmable output voltage; a primary side control circuit, which is coupled to the power switch circuit, for generating the operation signal according to a target control signal; an opto-coupler circuit, which is coupled to the secondary winding, for generating the target control signal according to the programmable output voltage and a programming signal; and a secondary side control circuit, which is coupled to the opto-coupler circuit and the secondary winding, for generating the programming signal according to the programmable output voltage and a setting signal; wherein the primary side control circuit determines whether an over voltage condition occurs according to a rate of increase of the feedback signal and a control level of the target control signal, or according to the rate of increase of the feedback signal and a rate of change of the target control signal, and the primary side control circuit generates an over voltage protection signal when the over voltage condition occurs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A control method of a flyback power supply circuit with a programmable function, comprising:
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receiving an input voltage; operating a power switch according to an operation signal, to converting an input voltage to a programmable output voltage; generating a feedback signal according to the programmable output voltage; generating the operation signal according to a target control signal; generating the target control signal according to the programmable output voltage and a programming signal; generating the programming signal according to the programmable output voltage and a setting signal; and determining whether an over voltage condition occurs according to a rate of increase of the feedback signal and a control level of the target control signal, or according to the rate of increase of the feedback signal and a rate of change of the target control signal, and generating an over voltage protection signal when the over voltage condition occurs. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A flyback power supply circuit with a programmable function, comprising:
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a transformer circuit, which includes; a primary winding, for receiving an input voltage; and a secondary winding, for generating a programmable output voltage at an output node; a power switch circuit, which is coupled to the primary winding, for operating a power switch therein according to an operation signal, so as to convert the input voltage to the programmable output voltage; a primary side control circuit, which is coupled to the power switch circuit, for generating the operation signal according to a target control signal; an opto-coupler circuit, which is coupled to the secondary winding, for generating the target control signal according to the programmable output voltage and a programming signal; and a secondary side control circuit, which is coupled to the opto-coupler circuit and the secondary winding, for generating the programming signal according to the programmable output voltage and a setting signal, and for determining whether to control the opto-coupler circuit to set the target control signal to a maximum level according to a fault signal; wherein when the target control signal is not set to the maximum level, the secondary control circuit controls the opto-coupler circuit to maintain the target control signal not to exceed a predetermined control level, wherein the predetermined control level is lower than the maximum level; and wherein when the target control signal is set to the maximum level, the primary side control circuit determines that an over voltage condition occurs and generates an over voltage protection signal. - View Dependent Claims (18, 19, 20)
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21. A control method of a flyback power supply circuit with a programmable function, comprising:
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receiving an input voltage; operating a power switch according to an operation signal, so as to convert the input voltage to a programmable output voltage; generating the operation signal according to a target control signal; generating the target control signal according to the programmable output voltage and a programming signal; generating the programming signal according to the programmable output voltage and a setting signal, and determining whether to set the target control signal to a maximum level according to a fault signal; when the target control signal is not set to the maximum level, the target control signal is maintained not to exceed a predetermined control level, wherein the predetermined control level is lower than the maximum level; and when the target control signal is set to the maximum level, determining that an over voltage condition occurs, and generating an over voltage protection signal. - View Dependent Claims (22, 23)
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Specification