A DC output switching power supply

Abstract

The present invention relates to a DC output switching power supply, comprising a switch control chip, a rectifier filter circuit, a start-up circuit, a voltage feedback sampling circuit, a current feedback protection circuit, a high-frequency transformer and an output rectifier circuit; the current feedback protection circuit is connected in parallel with the switch control chip; the input end of the rectifier filter circuit is connected to the AC input voltage, and the output end is connected to the input end of the start-up circuit and the switch control chip; the AC input voltage is rectified and filtered by the rectifier filter circuit to become a DC voltage, and the start-up circuit is connected to the switch control chip; the input end of the high-frequency transformer is connected to the switch control chip, and the output end is connected to the input end of the voltage feedback sampling circuit and the input end of the output rectifier circuit; the output end of the voltage feedback sampling circuit is connected to the switch control chip; and the output rectifier circuit outputs the DC voltage. The DC output switching power supply of the present invention can output a wide range of voltage, current, and power.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a direct current output switching power supply. Background Art

[0002] A DC output switching power supply is a power supply device that uses modern electronic technology to control the on-off time ratio of a switching transistor to maintain a stable output DC voltage. Existing DC switching power supplies are unable to output a wide range of voltage, current and power because the output current and power are limited. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a DC output switching power supply which can output a wide range of voltage, current and power.

[0004] In order to solve the above technical problems, the present invention provides a DC output switching power supply, including a switch control chip, a rectifier and filter circuit, a startup circuit, a voltage feedback sampling circuit, a high-frequency transformer and an output rectifier circuit; the input end of the rectifier and filter circuit is connected to the AC input voltage, and the output end is connected to the input end of the startup circuit and the switch control chip; the AC input voltage is rectified and filtered by the rectifier and filter circuit to become a DC voltage, and the startup circuit is connected to the switch control chip; the input end of the high-frequency transformer is connected to the switch control chip, and the output end is connected to the input end of the voltage feedback sampling circuit and the input end of the output rectifier circuit; the output end of the voltage feedback sampling circuit is connected to the switch control chip; and the output rectifier circuit outputs the DC voltage.

[0005] Furthermore, the switch control chip is an IW1816 chip.

[0006] Furthermore, the rectifier and filter circuit includes a resistor R1 connected to the AC input voltage, a rectifier stack D1 connected in series with the resistor R1, and a π-type filter circuit connected in parallel with the rectifier stack D1; the π-type filter circuit includes an inductor L1, and capacitors C1 and C2 connected in parallel at both ends of the inductor L1.

[0007] Furthermore, the startup circuit includes a resistor R2 connected to the sorting and filtering circuit, and capacitors C4 and C5 which are connected in parallel and have one end connected to the resistor R2 and the other end grounded.

[0008] Furthermore, the voltage feedback sampling circuit includes a resistor R7 connected to the output end of the high-frequency transformer, a resistor R5 connected in series with the resistor R7 and connected to the switch control chip, a resistor R6 and a capacitor C3 which are connected in parallel and have one end connected in sequence between the resistor R7 and the resistor R5 and the other end connected to the ground.

[0009] Furthermore, the output rectifier circuit includes a diode D3 whose anode is connected to the output end of the high-frequency transformer, a capacitor C6, a capacitor C7 and a resistor R8 which are connected in parallel and have one end connected to the cathode of the diode D3 and the other end grounded.

[0010] Furthermore, an auxiliary power supply circuit is included, the input end of the auxiliary power supply circuit is respectively connected to the output end of the startup circuit and the output end of the high-frequency transformer, the output end is connected to the switch control chip, and the startup circuit is connected to the switch control chip through the auxiliary power supply circuit. The auxiliary power supply circuit includes a diode D2 whose anode is connected to the output end of the high-frequency transformer, and a resistor R4 connected to the cathode of the diode D2, and the resistor R4 is respectively connected to the switch control chip and the startup circuit.

[0011] Furthermore, the current feedback protection circuit is a resistor R3 connected in parallel with the switch control chip.

[0012] The beneficial effects of the present invention are:

[0013] 1. After the AC input voltage passes through the rectifier and filter circuit, it outputs a DC high voltage, which is charged by the capacitors C4 and C5 of the startup circuit. When the VCC terminal of the switch control chip IW1816 reaches about 14V, the chip switch starts to conduct, the high-frequency transformer works, and the DC voltage is output. When the VCC terminal voltage drops to only about 4V, the chip switch is turned off. By designing a voltage feedback sampling circuit for the adjustment of the primary side of the transformer, the output voltage is adjusted through resistors R6 and R7 to achieve the adjustment of the output voltage range.

[0014] 2. By designing a current feedback protection circuit for periodic peak current control and limitation, the output power of the power supply is controlled by the size of the current limiting resistor R3. As the resistance value increases, the output power decreases, thereby achieving output current and power regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and implementation modes.

[0016] Figure 1 It is a structural block diagram of the present invention.

[0017] Figure 2 It is a circuit diagram of the present invention. DETAILED DESCRIPTION

[0018] like Figure 1 , Figure 2As shown, a DC output switching power supply includes a switch control chip I, a rectifier filter circuit II, a start-up circuit III, a voltage feedback sampling circuit IV, a current feedback protection circuit V, a high-frequency transformer VI, an output rectifier circuit VII and an auxiliary power supply circuit VIII. The switch control chip I is an IW1816 chip. The current feedback protection circuit V is connected in parallel with the switch control chip I; the input end of the rectifier filter circuit II is connected to the AC input voltage, and the output end is connected to the input end of the start-up circuit III and the switch control chip I. The AC input voltage is rectified and filtered by the rectifier filter circuit II to become a DC voltage, and the start-up circuit III is connected to the switch control chip I; the input end of the high-frequency transformer VI is connected to the switch control chip I, and the output end is connected to the input end of the voltage feedback sampling circuit IV and the input end of the output rectifier circuit VII; the output end of the voltage feedback sampling circuit IV is connected to the switch control chip I; the output rectifier circuit VII outputs the DC voltage.

[0019] The rectifier and filter circuit II includes a resistor R1 connected to the AC input voltage, a rectifier stack D1 connected in series with the resistor R1, and a π-type filter circuit connected in parallel with the rectifier stack D1; the π-type filter circuit includes an inductor L1, a capacitor C1 and a capacitor C2 connected in parallel at both ends of the inductor L1.

[0020] The startup circuit III includes a resistor R2 connected to the sorting and filtering circuit II, and capacitors C4 and C5 connected in parallel with one end connected to the resistor R2 and the other end grounded.

[0021] The voltage feedback sampling circuit IV includes a resistor R7 connected to the output end of the high-frequency transformer VI, a resistor R5 connected in series with the resistor R7 and connected to the switch control chip, a resistor R6 and a capacitor C3 which are connected in parallel and have one end connected in sequence between the resistor R7 and the resistor R5 and the other end connected to the ground.

[0022] The output rectifier circuit VII includes a diode D3 whose anode is connected to the output end of the high-frequency transformer, a capacitor C6, a capacitor C7 and a resistor R8 which are connected in parallel and have one end connected to the cathode of the diode D3 and the other end grounded.

[0023] The input end of the auxiliary power supply circuit VIII is respectively connected to the output end of the starting circuit III and the output end of the high-frequency transformer VI, and the output end is connected to the switch control chip I. The starting circuit III is connected to the switch control chip I through the auxiliary power supply circuit VIII.

[0024] The auxiliary power supply circuit VIII includes a diode D2 whose anode is connected to the output end of the high-frequency transformer VI, and a resistor R4 connected to the cathode of the diode D2. The resistor R4 is respectively connected to the switch control chip I and the start-up circuit III.

[0025] like Figure 2 As shown, the AC input voltage is rectified by the D1 bridge stack, the capacitor C1, the inductor L1, and the capacitor C2 of the π-type filter circuit, and then a DC high voltage is output. After the resistor R2 of the start-up circuit III, the capacitor C4 and the capacitor C5 are charged. When the VCC terminal of the switch control chip I reaches about 14V, the chip switch starts to conduct, the high-frequency transformer VI works, and the DC voltage is output. When the voltage at the VCC terminal of the switch control chip I is reduced to only about 4V, the switch of the switch control chip I is turned off. The 6-pin VSENSE terminal of the switch control chip I is a voltage feedback sampling circuit IV, which is used for auxiliary winding voltage detection and is used to adjust the primary side of the transformer. The output voltage is adjusted by resistors R6 and R7 to achieve the adjustment of the output voltage range; the 7-pin ISENSE terminal of the switch control chip I is a current feedback protection circuit, which performs primary side current detection and is used for cycle-by-cycle peak current control and limitation. The power output power is controlled by the size of the current limiting resistor R3. When the resistance value is increased, the output power is reduced, and the output current and power are adjusted.

[0026] The above description is exemplary and non-restrictive. Through the above description, those skilled in the art can realize many changes and modifications of the present invention, which will also fall within the spirit and scope of the present invention.

Claims

1. A DC output switching power supply, characterized in that: It includes a switch control chip, a rectifier filter circuit, a start-up circuit, a voltage feedback sampling circuit, a current feedback protection circuit, a high-frequency transformer and an output rectifier circuit; the current feedback protection circuit is connected in parallel with the switch control chip; The input end of the rectifier and filter circuit is connected to the AC input voltage, and the output end is connected to the input end of the start-up circuit and the switch control chip. The AC input voltage is rectified and filtered by the rectifier and filter circuit to become a DC voltage, and the start-up circuit is connected to the switch control chip; the input end of the high-frequency transformer is connected to the switch control chip, and the output end is connected to the input end of the voltage feedback sampling circuit and the input end of the output rectifier circuit; the output end of the voltage feedback sampling circuit is connected to the switch control chip; the output rectifier circuit outputs the DC voltage; The rectifier filter circuit includes a resistor R1 connected to an AC input voltage, a rectifier stack D1 connected in series with the resistor R1, and a π-type filter circuit connected in parallel with the rectifier stack D1; the π-type filter circuit includes an inductor L1, a capacitor C1 and a capacitor C2 connected in parallel at both ends of the inductor L1; The startup circuit includes a resistor R2 connected to the rectifier and filter circuit, and capacitors C4 and C5 connected in parallel with one end connected to the resistor R2 and the other end grounded; The voltage feedback sampling circuit includes a resistor R7 connected to the output end of the high-frequency transformer, a resistor R5 connected in series with the resistor R7 and connected to the switch control chip, a resistor R6 and a capacitor C3 connected in parallel with one end connected in sequence between the resistor R7 and the resistor R5 and the other end connected to the ground; The output rectifier circuit includes a diode D3 whose anode is connected to the output end of the high-frequency transformer, a capacitor C6, a capacitor C7 and a resistor R8 which are connected in parallel and one end of which is respectively connected to the cathode of the diode D3 and the other end is grounded; It also includes an auxiliary power supply circuit, the input end of the auxiliary power supply circuit is respectively connected to the output end of the starting circuit and the output end of the high-frequency transformer, the output end is connected to the switch control chip, and the starting circuit is connected to the switch control chip through the auxiliary power supply circuit; The auxiliary power supply circuit includes a diode D2 whose anode is connected to the output end of the high-frequency transformer, and a resistor R4 connected to the cathode of the diode D2. The resistor R4 is connected to the switch control chip and the start-up circuit respectively.

2. The DC output switching power supply according to claim 1, characterized in that: The switch control chip is an IW1816 chip.

3. The DC output switching power supply according to claim 1, characterized in that: The current feedback protection circuit is a resistor R3 connected in parallel with the switch control chip.

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