Circuit for output voltage error detect and feedback in smps

An error feedback circuit for a Switching Mode Power Supply (SMPS), the error feedback circuit detecting an error of an output voltage of the SMPS from a winding voltage of a magnetic energy transfer element, and feeding back the detected error, comprising:

• a flyback period detection circuit for detecting a flyback period from the winding voltage;
• a comparison unit for comparing the winding voltage with a reference voltage and outputting a result of comparison;
• a logic unit for outputting error information of an output voltage of the magnetic energy transfer element according to a flyback period detection output of the flyback period detection circuit and an output of the comparison unit;
• and
• an up/down control unit for outputting a feedback value corresponding to the error information output from the logic unit,
• whereby the error feedback circuit detects a period during which the winding voltage is higher than a reference voltage, and a period during which the winding voltage is lower than the reference voltage, in a flyback period of the magnetic energy transfer element, determines a difference between a ratio of the period, during which the winding voltage is higher than the reference voltage, to the flyback period and a preset value, detects an error of the output voltage of the SMPS, and feeds back the detected error.

An error feedback circuit for a Switching Mode Power Supply (SMPS), the error feedback circuit detecting an error of an output voltage of the SMPS from a winding voltage of a magnetic energy transfer element, and feeding back the detected error, comprising:

• a flyback period detection circuit for detecting a flyback period from the winding voltage;
• a comparison unit for comparing the winding voltage with a reference voltage and outputting a result of comparison;
• an up/down control unit for outputting a charge current or a discharge current according to the result of comparison;
• a switch, an on/off operation of which is controlled by the flyback period detection circuit and which is configured to transfer the charge current or the discharge current from the up/down control unit to a subsequent stage;
• and
• a feedback condenser charged and discharged with the charge current and the discharge current, respectively, which are output from the up/down control unit, when the switch is in a closed state, wherein the charge voltage of the feedback condenser is fed back,
• whereby the error feedback circuit detects a period during which the winding voltage is higher than a reference voltage, and a period during which the winding voltage is lower than the reference voltage, in a flyback period of the magnetic energy transfer element, determines a difference between a ratio of the period, during which the winding voltage is higher than the reference voltage, to the flyback period and a preset value, detects an error of the output voltage of the SMPS, and feeds back the detected error.

An output voltage control method for a Switching Mode Power Supply (SMPS), the SMPS including a magnetic energy transfer element for storing magnetic energy using an excitation current, and transferring the magnetic energy;

• a switching element connected to one end of the winding of the magnetic energy transfer element and configured to control current of the winding of the magnetic energy transfer element;
• a control unit for controlling the switching element through feedback;
• and a feedback winding of the magnetic energy transfer element, wherein said method comprises:
• detecting a period, during which a voltage of the feedback winding is higher than a reference voltage, and a period, during which the voltage of the feedback winding is lower than the reference voltage, in a flyback period of the magnetic energy transfer element;
• determining a difference between a ratio of the period, during which the voltage of the feedback winding is higher than the reference voltage, to the flyback period and a preset value, detecting an error of the output voltage of the SMPS;
• and
• feeding the detected error back to the control unit, thus controlling the output voltage.