Low-power consumption feedback circuit for control chip of AC-DC switching power supply

A technology for controlling chips and feedback circuits, applied to electrical components, output power conversion devices, and conversion of AC power input to DC power output. Simple, solve the effect of large no-load loss

Inactive Publication Date: 2011-04-06
西安英洛华微电子有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This compromise setting fails to solve the problem of large power supply no-load loss, and the resulting loss gen...

Method used

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  • Low-power consumption feedback circuit for control chip of AC-DC switching power supply
  • Low-power consumption feedback circuit for control chip of AC-DC switching power supply
  • Low-power consumption feedback circuit for control chip of AC-DC switching power supply

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Embodiment Construction

[0012] see figure 1 , 2 , it has a resistor divider, the resistor divider of this example is made up of current-limiting resistor 101, diode 102, resistor 103, resistor 104 connected in series, the feedback terminal FB of described control chip 10 is connected to resistor 101 and diode 102 At the positive pole series point, the built-in power supply Vdd outputs current to the feedback terminal FB through the resistor 101, and then flows to the ground through the photosensitive tube in the optical coupler 601; the diode 102 acts as a one-way conduction to prevent the current in the resistor divider from being reversed. to flow; the series connection point of the resistor 103 and the resistor 104 provides a divided voltage value, which is used as the threshold for the detection of the drain-source current of the switching tube 20, and the divided voltage value is sent to the positive input terminal of the comparator 105, and the comparator 105 The negative input terminal of th...

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PUM

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Abstract

The invention relates to a low-power consumption feedback circuit for a control chip of an AC-DC switching power supply. The feedback circuit comprises a resistor divider; a current limiting resistor for controlling the output current of the feedback end of the chip is connected in the resistor divider in series; a parallel branch consisting of a bleeder resistor and a bleeder switch which are connected in series is arranged on the current limiting resistor; the bleeder switch is controlled by a comparator; and a comparison signal is obtained from comparing a resonant signal with a reference voltage. In the invention, the resistance of the current limiting resistor is increased to reduce the output current of the feedback end of the control chip in an idle state, so as to reduce no-load loss. The resonant detection signal is skillfully multiplexed to indirectly detect an output voltage VO so as to cause the feedback end of the control chip to bleed when the VO shoots down, thereby preventing the response speed reduction of the control chip, which is caused by only increasing the current limiting resistor. By using the invention,the problem of large idle loss of the power is solved,and the feedback circuit has the advantages of simple circuit structure and low cost and is convneient to be integrated.

Description

technical field [0001] The invention relates to a control chip of an AC-DC switching power supply, in particular to a low-power feedback circuit of the control chip of an AC-DC switching power supply. Background technique [0002] The existing flyback AC-DC switching power supply such as figure 2 As shown, it mainly includes a transformer 30, an output voltage sampling circuit 60, a control chip 10, a switching tube 20 and a quasi-resonant signal detection circuit 80. The transformer 30 is used to isolate input and output, and the control chip 10 is based on the load (ie The change of the output terminal voltage) controls the input voltage V accordingly by adjusting the duty cycle of the switch tube 20 conducting in The energy transferred from the primary side of the transformer to the secondary side in each cycle, so that the output voltage V O Follow the set value and keep unchanged, meanwhile, the control chip 10 also controls the conduction of the switch tube 20 at the...

Claims

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Application Information

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IPC IPC(8): H02M7/217
Inventor 许煌樟方建平宋利军
Owner 西安英洛华微电子有限公司
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