Switching power supply control circuit

A switching power supply and control circuit technology, applied in the direction of electrical components, output power conversion devices, etc., can solve the problems of adjustment control and impossibility, and achieve the effect of improving poor dynamic characteristics

Active Publication Date: 2020-05-08
MORNSUN GUANGZHOU SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] However, for some current-controlled switching power supplies, externally connecting a resistor with a fixed resistance or a capacitor with a fixed value to the current control pin of the current-...

Method used

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Examples

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Effect test

no. 1 example

[0039] The LLC resonant converter is a typical current-controlled switching power supply. In the design of the LLC resonant converter, the designer generally knows that the higher the frequency of the circuit during the start-up process of the converter, the better. In this case, the high-resistance characteristics exhibited will suppress the large inrush current generated by the action of the semiconductor switching device on the resonant cavity during the start-up process of the converter, and furthermore, it will also reduce the large voltage stress generated at both ends of the resonant capacitor . Obviously, if the operating frequency of the converter is not increased at start-up, power supply designers often choose switching transistors with larger current margins and film capacitors with higher withstand voltage values ​​for the design of LLC resonant converters. However, high-current switching transistors and high-voltage film capacitors also mean increased design cost...

no. 2 example

[0063] Such as Figure 4 As shown, it is a functional block diagram of the second embodiment of the present invention, which is different from the first embodiment in that a resistor R5 is added to the trigger circuit 11 . One end of the resistor R5 is used to connect the bus voltage V of the LLC resonant converter input BUS , the other end of the resistor R5 is connected to the output end of the comparator U1A. Here, the working principle of controlling the frequency during startup of the LLC resonant converter is the same as that of the first embodiment, and will not be repeated here. Only the changes in the principle of the circuit brought about by adding the resistor R5 are described.

[0064] The output pull-up resistors R4 and R5 of the comparator U1A are respectively connected to a constant voltage V CC The bus voltage V of the LLC resonant converter BUS . Since the output terminal of the comparator U1A is connected to the bus voltage through the resistor R5, it pr...

no. 3 example

[0067] Such as Figure 5 As shown, it is the functional block diagram of the third embodiment of the present invention. The difference from the second embodiment is that the trigger circuit 11 also adds a diode D1, a diode D2 and a resistor R6; the anode of the diode D1 is connected to the bus voltage V of the LLC resonant converter BUS , the cathode of the diode D1 is connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the output end of the comparator U1A. The anode of diode D2 is connected to the voltage signal V converted by temperature change TMP, the cathode of the diode D2 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the output end of the comparator U1A. Here, the working principle of controlling the frequency during the start-up of the LLC resonant converter is still the same as that of the first embodiment, and will not be repeated here. Only the changes in the principle of ...

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PUM

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Abstract

The invention discloses a switching power supply control circuit. The method is applied to a current-controlled switching power supply. The switching power supply control circuit is characterized in that the switching power supply control circuit comprises a trigger circuit and a current source control circuit, and the trigger circuit samples a state signal of a working state pin of the switchingpower supply control chip through the input end of the trigger circuit; compared with a reference voltage VREF, when the state signal does not reach the reference voltage VREF, the output end of the trigger circuit provides a current for the input end of the current source control circuit, the current source control circuit works under the action of the current source, and a current value of a current control pin of the switching power supply control chip is increased; and when the state signal reaches the reference voltage VREF, the output end of the trigger circuit does not provide a currentsource for the input end of the current source control circuit, and the current source control circuit does not work. According to the invention, the output frequency can be adjusted and controlled when the switching power supply is in a starting stage, and the problems of large ripple noise and poor dynamic characteristics of the switching power supply in a no-load or light-load state can be solved.

Description

technical field [0001] The invention relates to a switching power supply, in particular to a current source control circuit of a current-controlled switching power supply. Background technique [0002] With the continuous progress and development of switching power supply technology, there are more and more topology options for switching power supply circuits. For these different circuit topologies, major semiconductor manufacturers at home and abroad have also launched their own control chips. However, referring to the technical manuals of switching power supply control chips released by major semiconductor manufacturers, it can be found that a large number of current source circuits are used inside the control chip. The current changes of these current source circuits are often associated with a certain function or state of the power control chip. [0003] In order to better describe the background technology of the present invention, relevant terms are defined as follows...

Claims

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Application Information

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IPC IPC(8): H02M1/08H02M1/36
CPCH02M1/08H02M1/36
Inventor 张聪杨志潘成章
Owner MORNSUN GUANGZHOU SCI & TECH
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