Switching power source control circuit and switching power source

Abstract

The invention relates to a switching power source control circuit and a switching power source. The switching power source comprises a transformer, a power supply circuit, a power switch, an output circuit, a sampling feedback circuit and a control circuit; the transformer comprises a primary winding, a secondary winding and an auxiliary winding; the power supply circuit is connected with the auxiliary winding and is used for inputting auxiliary voltage outputted by the auxiliary winding and outputting power supply voltage based on the auxiliary voltage; the power switch is connected with the primary winding; the output circuit is connected with the secondary winding; the sampling feedback circuit is connected with the output circuit and outputs feedback signals; and the control circuit is connected with the sampling feedback circuit, the power switch and the power supply circuit and controls current in the primary winding through the power switch based on the feedback signals so as to make the secondary winding output variable and adjustable power source voltage and to make the auxiliary voltage outputted by the auxiliary winding provided for the control circuit as power supply voltage through the power supply circuit. With the switching power source of the invention adopted, the power supply requirement of the control circuit is satisfied, loss can be reduced, efficiency can be improved, and costs can be effectively saved with the same function requirements satisfied. The switching power source is suitable for circuits which have requirements for the range of power supply voltage.

Description

technical field [0001] The present invention relates to the technical field of switching power supply, and more specifically, relates to a switching power supply control circuit and a switching power supply. Background technique [0002] In the current switching power supply, due to the relatively large output voltage range (generally 5V-20V), the power supply voltage (VDD) of the control IC of the switching power supply is too large to exceed the maximum VDD of the control IC and cannot work. However, the current switching power supply is mostly single-stage output, and the VDD power supply of the control IC is provided by the transformer, and the output voltage changes the same, so the voltage fluctuation range is large. And because the transmission of the previous USB cannot meet the needs of the current social development, a new standard has been introduced. The new standard can be applied to a wider range of electrical equipment and signal transmission, saving equipment...

AI Technical Summary

Problems solved by technology

[0002] In the current switching power supply, due to the relatively large output voltage range (generally 5V to 20V), the power supply voltage (VDD) of the control IC of the switching power supply is too large to exceed the maximum VDD of the control IC and cannot work.

However, the current switching power supply is mostly single-stage output, and the VDD power supply of the control IC is provided by the transformer, and the output voltage changes the same, so the voltage fluctuation range is large.

And because the transmission of the previous USB cannot meet the needs of the current social development, a new standard has been introduced. The new standard can be applied to a wider range of electrical equipment and signal transmission, saving equipment and equipment, power supply and equipment. The advantages of connecting wires between the

However, this new standard has greater requirements for power supply equipment. For example, due to the large output voltage range mentioned above, the VDD of the power supply IC exceeds the working range of the power supply IC. The common method for this problem is to increase the voltage regulator circuit to adjust the power supply IC. VDD, but this practice will often make the voltage added to the voltage regulator circuit, causing the power device to heat up and increase the loss, which will affect the safety of the switching power supply and shorten the service life

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