A dual output circuit based on primary feedback and single secondary winding

Abstract

The present invention provides a dual-channel output circuit based on primary feedback and a single secondary winding, comprising a transformer, a power and control circuit connected to the primary side of the transformer for realizing main power conversion and control functions, a winding feedback circuit connected to the primary side of the transformer for primary sampling and realizing feedback functions, and a dual-channel output voltage stabilizing circuit connected to the secondary side of the transformer. The present invention proposes a dual-channel output circuit based on primary feedback and a single secondary winding, adopting a primary sampling feedback form and a single secondary winding output to realize two-channel stable output; not only does it greatly reduce the impact of load changes on the output voltage, but it also realizes two-channel output only through a single transformer, which simplifies the circuit structure while reducing the difficulty of making the transformer, thereby reducing the difficulty of making related products.

Description

Technical Field

[0001] The invention relates to the technical field of switch power supply circuits, and in particular to a dual-path output circuit based on primary side feedback and a single secondary side winding. Background Art

[0002] Under the existing technology, there are two common circuit implementation forms for low-power isolation converters with dual output: one is to determine one of the paths as the main path and the other as the auxiliary path, and use an optocoupler or an isolation transformer on the secondary side to perform feedback control on the main path to keep the main path stable, and the auxiliary path uses winding coupling to follow the output of the main path to achieve dual output; the other is to sample the positive and negative outputs of the circuit at the same time, and use an optocoupler or an isolation transformer on the secondary side for isolated feedback to achieve dual output stability.

[0003] Although both of the above two circuits can achieve dual-channel output, they have the following disadvantages: 1) Since the auxiliary output is uncontrolled, its output voltage will change greatly with the change of load; 2) The main circuit is isolated by optocoupler or isolation transformer, and a reference source and error amplifier need to be set up. The circuit structure is complicated, which increases the circuit cost; 3) Each output voltage requires a transformer pin, and another pin is required for the common point. The transformer winding is complicated, which increases the difficulty of manufacturing related products. Summary of the invention

[0004] The object of the present invention is to provide a dual-output circuit based on primary feedback and a single secondary winding to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A dual-channel output circuit based on primary-side feedback and a single secondary winding comprises a transformer, a power and control circuit connected to the primary side of the transformer for realizing main power conversion and control functions, a winding feedback circuit connected to the primary side of the transformer for performing primary sampling and realizing feedback functions, and a dual-channel output voltage stabilizing circuit connected to the secondary side of the transformer.

[0007] Furthermore, the transformer includes primary sides TA1-TA2, TB1-TB2 and secondary sides TC1-TC2, wherein the TA1 terminal serves as a voltage input terminal.

[0008] Furthermore, the power and control circuit includes a PWM controller, a MOS tube V1 and a sampling resistor R1, the PWM controller is connected to the gate of the MOS tube V1, the drain of the MOS tube V1 is connected to the TA2 terminal, the source is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the TB1 terminal and grounded.

[0009] Further, the winding feedback circuit includes resistors R2, R3, and R4, capacitors C1, C2, C3, and diodes V2 and V3. The TB2 end is respectively connected to the positive electrode of the diode V2 and the other end of the resistor R2, the negative electrode of the diode V2 is respectively connected to one end of the capacitor C1 and the PWM controller, the other end of the resistor R2 is respectively connected to the positive electrode of the diode V3 and one end of the capacitor C2, the negative electrode of the diode V3 is respectively connected to one end of the resistor R3 and one end of the capacitor C3, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and the PWM controller, and the other ends of the capacitors C1, C2, C3 and the resistor R4 are connected and grounded.

[0010] Furthermore, the dual-output voltage stabilizing circuit includes a diode V4, a capacitor C4, a resistor R5, and voltage stabilizing tubes V5 and V6. The positive electrode of the diode V4 is connected to the TC2 end, one end of the capacitor C4 is respectively connected to the negative electrode of the diode V4 and one end of the resistor R5, the other end of the capacitor C4 is respectively connected to TC1 and the positive electrode of the voltage stabilizing tube V5, the positive electrode of the voltage stabilizing tube V5 serves as the negative output end, the positive electrode of the voltage stabilizing tube V6 is connected to the negative electrode of the voltage stabilizing tube V5 and is grounded, and the negative electrode of the voltage stabilizing tube V6 serves as the positive output end and is connected to the other end of the resistor R5.

[0011] It can be seen from the above technical solutions that the present invention proposes a dual-channel output circuit based on primary feedback and a single secondary winding, and adopts a primary sampling feedback form and a single secondary winding output to achieve two-channel stable output; not only does it greatly reduce the impact of load changes on the output voltage, but it also achieves two-channel output with only a single transformer, which simplifies the circuit structure while reducing the difficulty of transformer manufacturing, thereby reducing the difficulty of manufacturing related products. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the circuit principle connection of the present invention. DETAILED DESCRIPTION

[0013] A preferred embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific implementation disclosed below.

[0014] The dual-channel output circuit based on primary feedback and single secondary winding described in this preferred embodiment includes a transformer, a power and control circuit connected to the primary side of the transformer for realizing main power conversion and control functions, a winding feedback circuit connected to the primary side of the transformer for primary sampling and realizing feedback functions, and a dual-channel output voltage stabilization circuit connected to the secondary side of the transformer. Specifically, Figure 1 As shown:

[0015] The transformer includes primary sides TA1-TA2, TB1-TB2 and secondary sides TC1-TC2, wherein the TA1 terminal serves as a voltage input terminal;

[0016] The power and control circuit includes a PWM controller, a MOS tube V1 and a sampling resistor R1, wherein the PWM controller is connected to the gate of the MOS tube V1, the drain of the MOS tube V1 is connected to the TA2 terminal, the source is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the TB1 terminal and grounded;

[0017] The winding feedback circuit includes resistors R2, R3, and R4, capacitors C1, C2, and C3, and diodes V2 and V3. The TB2 end is respectively connected to the positive electrode of the diode V2 and the other end of the resistor R2, the negative electrode of the diode V2 is respectively connected to one end of the capacitor C1 and the PWM controller, the other end of the resistor R2 is respectively connected to the positive electrode of the diode V3 and one end of the capacitor C2, the negative electrode of the diode V3 is respectively connected to one end of the resistor R3 and one end of the capacitor C3, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and the PWM controller, and the capacitors C1, C2, and C3 are respectively connected to one end of the resistor R4 and the PWM controller. And the other end of the resistor R4 is connected and grounded; wherein the diode V2 and the capacitor C1 form a rectifier filter circuit, which is used to rectify the high-frequency pulse voltage output through the winding TB1-TB2 to obtain a DC voltage to power the PWM controller, and the resistor R2 and the capacitor C2 form a low-pass filter, which is used to suppress the leading edge voltage spike of the high-frequency pulse signal generated by the positive electrode of the diode V2. The signal is output to a DC voltage signal after passing through the rectifier filter circuit composed of the diode V3 and the capacitor C3, and the DC voltage signal is output to a feedback signal entering the PWM controller after passing through the voltage divider circuit composed of the resistors R3 and R4.

[0018] The dual-path output voltage stabilizing circuit includes a diode V4, a capacitor C4, a resistor R5, and voltage regulator tubes V5 and V6. The positive electrode of the diode V4 is connected to the TC2 end, one end of the capacitor C4 is respectively connected to the negative electrode of the diode V4 and one end of the resistor R5, the other end of the capacitor C4 is respectively connected to TC1 and the positive electrode of the voltage regulator tube V5, the positive electrode of the voltage regulator tube V5 serves as the negative path output end, the positive electrode of the voltage regulator tube V6 is connected to the negative electrode of the voltage regulator tube V5 and is grounded, and the negative electrode of the voltage regulator tube V6 serves as the positive path output end and is connected to the other end of the resistor R5; wherein the diode V4 and the capacitor C4 form a rectifier and filter circuit, which is used to rectify the high-frequency pulse voltage output through the windings TC1-TC2 to obtain a DC voltage.

[0019] It can be seen that the present invention adopts the primary side sampling feedback form and the single secondary winding output to realize two-way stable output; not only the influence of the output voltage on the load change is greatly reduced, but also compared with the prior art, the optocoupler or isolation transformer in the secondary side feedback is omitted, and the two-way output is realized only by a single transformer, which simplifies the circuit structure and reduces the difficulty of transformer manufacturing, thereby reducing the difficulty of manufacturing related products.

[0020] The above-described embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A dual-output circuit based on primary feedback and a single secondary winding, comprising a transformer, characterized in that: It also includes a power and control circuit connected to the primary side of the transformer for realizing main power conversion and control functions, a winding feedback circuit connected to the primary side of the transformer for primary sampling and realizing feedback functions, and a dual-channel output voltage stabilization circuit connected to the secondary side of the transformer; The transformer includes primary sides TA1-TA2, TB1-TB2 and secondary sides TC1-TC2, wherein the TA1 terminal is used as a voltage input terminal; The winding feedback circuit includes resistors R2, R3, and R4, capacitors C1, C2, and C3, and diodes V2 and V3. The TB2 end is respectively connected to the positive electrode of the diode V2 and the other end of the resistor R2, the negative electrode of the diode V2 is respectively connected to one end of the capacitor C1 and the PWM controller, the other end of the resistor R2 is respectively connected to the positive electrode of the diode V3 and one end of the capacitor C2, the negative electrode of the diode V3 is respectively connected to one end of the resistor R3 and one end of the capacitor C3, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and the PWM controller, and the other ends of the capacitors C1, C2, C3 and the resistor R4 are connected and grounded; The dual-path output voltage stabilizing circuit includes a diode V4, a capacitor C4, a resistor R5, and voltage stabilizing tubes V5 and V6. The positive electrode of the diode V4 is connected to the TC2 end, one end of the capacitor C4 is respectively connected to the negative electrode of the diode V4 and one end of the resistor R5, the other end of the capacitor C4 is respectively connected to TC1 and the positive electrode of the voltage stabilizing tube V5, the positive electrode of the voltage stabilizing tube V5 serves as the negative path output end, the positive electrode of the voltage stabilizing tube V6 is connected to the negative electrode of the voltage stabilizing tube V5 and is grounded, and the negative electrode of the voltage stabilizing tube V6 serves as the positive path output end and is connected to the other end of the resistor R5.

2. The dual-output circuit based on primary feedback and single secondary winding according to claim 1, characterized in that: The power and control circuit includes a PWM controller, a MOS tube V1 and a sampling resistor R1. The PWM controller is connected to the gate of the MOS tube V1. The drain of the MOS tube V1 is connected to the TA2 terminal, the source is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the TB1 terminal and grounded.

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