Power conversion apparatus and over current protection method thereof
First Claim
1. A power conversion apparatus, comprising:
- a transformer, having a primary side and a secondary side, wherein a first end of the primary side receives an input voltage, and the secondary side provides an output voltage to an electronic device;
a power switch, having a first end coupled to a second end of the primary side, a second end coupled to a first node, and a control end receiving a pulse width modulation signal;
a first resistor, coupled between the first node and a ground potential;
a feedback unit, coupled to the secondary side, for receiving the output voltage, and accordingly outputting a feedback signal related to a loading status of the electronic device; and
a pulse width modulation controller chip, coupled to the control end of the power switch, the first node and the feedback unit, for generating an over current protection reference signal with variable slope according to the feedback signal and a system operation voltage of the pulse width modulation controller chip, and accordingly comparing a voltage of the first node and the over current protection reference signal with variable slope to determine whether or not to generate the pulse width modulation signal to switch the power switch.
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Abstract
A power conversion apparatus and an over current protection (OCP) method thereof are provided. The OCP method includes generating a pulse-width-modulation (PWM) signal according to a loading status of an electronic device, so as to switch a power switch in the power conversion apparatus and thus making the power conversion apparatus providing an output voltage to the electronic device; generating an OCP reference signal with variable slope according to a feedback signal related to the loading status of the electronic device and a system operation voltage of a PWM controller chip in the power conversion apparatus that is used for generating the PWM signal; and comparing a sensing voltage corresponding to a current following through the power switch on a resistor, and the OCP reference signal with variable slope to determine whether to activate an OCP mechanism to control the PWM controller chip whether to generate the PWM signal.
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Citations
9 Claims
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1. A power conversion apparatus, comprising:
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a transformer, having a primary side and a secondary side, wherein a first end of the primary side receives an input voltage, and the secondary side provides an output voltage to an electronic device; a power switch, having a first end coupled to a second end of the primary side, a second end coupled to a first node, and a control end receiving a pulse width modulation signal; a first resistor, coupled between the first node and a ground potential; a feedback unit, coupled to the secondary side, for receiving the output voltage, and accordingly outputting a feedback signal related to a loading status of the electronic device; and a pulse width modulation controller chip, coupled to the control end of the power switch, the first node and the feedback unit, for generating an over current protection reference signal with variable slope according to the feedback signal and a system operation voltage of the pulse width modulation controller chip, and accordingly comparing a voltage of the first node and the over current protection reference signal with variable slope to determine whether or not to generate the pulse width modulation signal to switch the power switch. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An over current protection method, adapted to a power conversion apparatus, the over current protection method comprising:
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generating a pulse width modulation signal according to a loading status of an electronic device, so as to switch a power switch in the power conversion apparatus and thus make the power conversion apparatus to provide an output voltage to the electronic device; generating an over current protection reference signal with variable slope according to a feedback signal related to the loading status of the electronic device and a system operation voltage of a pulse width modulation controller chip in the power conversion apparatus that is used for generating the pulse width modulation signal; and comparing a sensing voltage corresponding to a current following through the power switch on a resistor to the over current protection reference signal with variable slope so as to determine whether or not to activate an over current protection mechanism to control the pulse width modulation controller chip whether or not to generate the pulse width modulation signal. - View Dependent Claims (8, 9)
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Specification