Feedback circuit for power supply device

Abstract

The invention provides a feedback circuit for a power supply device. The power supply device comprises a primary side circuit and a secondary side circuit. The feedback circuit comprises a feedback voltage generation circuit, a reference voltage generation circuit and a compensation signal generation circuit. The feedback voltage generating circuit is electrically connected to the secondary side circuit. The feedback voltage generating circuit generates a feedback voltage according to the bias voltage and an output voltage of the power supply device. The reference voltage generating circuit provides a reference voltage according to the feedback voltage. The compensation signal generation circuit generates a compensation signal according to a feedback voltage and a reference voltage, and provides the compensation signal to a controller in the primary side circuit. The voltage value of the feedback voltage is lower than the voltage value of the bias voltage. The voltage value of the feedback voltage changes along with the change of the output voltage.

Description

Technical Field

[0001] The invention relates to a feedback circuit, and in particular to a feedback circuit for a power supply device. Background Art

[0002] Generally speaking, current power supply devices may include a feedback circuit. The feedback circuit provides feedback results directly based on the change of the output voltage located in the secondary side circuit. The primary side circuit of the power supply device adjusts the operating parameters based on the feedback results. Therefore, the output voltage can be monitored to provide a stable output voltage value.

[0003] However, when the power supply device is a boost circuit, the voltage value of the output voltage is higher. Therefore, the power consumption of the feedback circuit itself is higher. The efficiency of the power supply device will decrease due to the high power consumption of the feedback circuit itself. Therefore, how to reduce the power consumption of the feedback circuit is one of the research focuses of those skilled in the art. Summary of the invention

[0004] The invention provides a feedback circuit for a power supply device, which can reduce the power consumption of the feedback circuit.

[0005] The feedback circuit of the present invention is used for a power supply device. The power supply device includes a primary side circuit and a secondary side circuit. The feedback circuit includes a feedback voltage generating circuit, a reference voltage generating circuit and a compensation signal generating circuit. The feedback voltage generating circuit is electrically connected to the secondary side circuit. The feedback voltage generating circuit receives a bias voltage and an output voltage of the power supply device, and generates a feedback voltage according to the bias voltage and the output voltage. The reference voltage generating circuit is electrically connected to the feedback voltage generating circuit. The reference voltage generating circuit provides a reference voltage according to the feedback voltage. The compensation signal generating circuit is electrically connected to the feedback voltage generating circuit and a controller in the primary side circuit. The compensation signal generating circuit generates a compensation signal according to the feedback voltage and the reference voltage, and provides the compensation signal to the controller. The voltage value of the feedback voltage is lower than the voltage value of the bias voltage. The voltage value of the feedback voltage changes with the change of the output voltage.

[0006] Based on the above, the feedback voltage generating circuit generates the feedback voltage according to the bias voltage and the output voltage. The voltage value of the feedback voltage is lower than the voltage value of the bias voltage. The voltage value of the feedback voltage changes with the change of the output voltage. The voltage value of the feedback voltage is limited. In this way, the power consumption of the feedback circuit is reduced. The efficiency of the power supply device will increase due to the low power consumption of the feedback circuit itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of a power supply device according to an embodiment of the present invention;

[0008] Figure 2 is a circuit diagram of a feedback circuit according to an embodiment of the present invention.

[0009] Description of Reference Numerals

[0010] 100: Power supply device

[0011] 110: Primary circuit

[0012] 111: Controller

[0013] 120: Secondary circuit

[0014] 130, 230: Feedback circuit

[0015] 131, 231: Feedback voltage generation circuit

[0016] 132, 232: Reference voltage generation circuit

[0017] 133, 233: Compensation signal generation circuit

[0018] 2311: Voltage divider circuit

[0019] 2312: Semiconductor components

[0020] 2321: Voltage Regulator

[0021] 2322~2324: Voltage-stabilizing impedance circuit

[0022] 2331: Light-emitting components

[0023] 2332: Photodiode

[0024] C1: Capacitor

[0025] R1, R2: Resistors

[0026] RD1, RD2: voltage divider resistors

[0027] RS1~RS3: Resistors

[0028] SC: Compensation signal

[0029] TR: Transformer

[0030] VB: Bias voltage

[0031] VF: Feedback voltage

[0032] VFS: reference voltage

[0033] VIN: Input voltage

[0034] VO: Output voltage

[0035] VR: conversion voltage

[0036] ΔVF: Feedback voltage difference DETAILED DESCRIPTION

[0037] Some embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. The referenced element symbols in the following description will be regarded as the same or similar elements when the same element symbols appear in different drawings. These embodiments are only part of the present invention and do not disclose all possible implementation methods of the present invention. More specifically, these embodiments are only examples within the scope of the patent application of the present invention.

[0038] Please refer to Figure 1 , Figure 1 1 is a schematic diagram of a power supply device according to an embodiment of the present invention. In this embodiment, the power supply device 100 includes a primary side circuit 110, a secondary side circuit 120 and a feedback circuit 130. The primary side circuit 110 receives an input voltage VIN. The power supply device 100 provides a conversion voltage VR according to the input voltage VIN. The secondary side circuit 120 receives the conversion voltage VR and provides an output voltage VO according to the conversion voltage VR. The power supply device 100 can be any form of power conversion circuit. For example, the power supply device 100 can be a boost circuit, a buck circuit or an LLC resonant conversion circuit (but the present invention is not limited to this). In this embodiment, the power supply device 100 also includes a transformer TR (but the present invention is not limited to this). The transformer TR is used to provide the conversion voltage VR. In this embodiment, the primary side circuit 110 includes a controller 111. For example, the controller 111 can control the switching operation of a power transistor (not shown) in the primary side circuit 110. The switching operation of the power transistor can determine the voltage value of the conversion voltage VR.

[0039] In this embodiment, the primary side circuit 110 includes a controller 111. The feedback circuit 130 receives the output voltage VO and provides a compensation signal SC according to the output voltage VO. The controller 111 provides corresponding operations in response to the compensation signal SC, thereby stabilizing the output voltage VO.

[0040] In the present embodiment, the feedback circuit 130 includes a feedback voltage generating circuit 131, a reference voltage generating circuit 132, and a compensation signal generating circuit 133. The feedback voltage generating circuit 131 is electrically connected to the secondary side circuit 120. The feedback voltage generating circuit 131 receives the bias voltage VB and the output voltage VO of the power supply device 100, and generates a feedback voltage VF according to the bias voltage VB and the output voltage VO. The reference voltage generating circuit 132 is electrically connected to the feedback voltage generating circuit 131. The reference voltage generating circuit 132 generates a reference voltage VFS according to the feedback voltage VF. The compensation signal generating circuit 133 is electrically connected to the feedback voltage generating circuit 131 and the controller 111. The compensation signal generating circuit 133 generates a compensation signal SC according to the feedback voltage VF and the reference voltage VFS, and provides the compensation signal SC to the controller 111.

[0041] In this embodiment, the bias voltage VB has a fixed voltage value and can be adjusted based on actual usage requirements.

[0042] In this embodiment, the voltage value of the feedback voltage VF is lower than the voltage value of the bias voltage VB. The voltage value of the feedback voltage VF changes with the change of the output voltage VO. It is worth mentioning that the voltage value of the feedback voltage VF is limited by the voltage value of the bias voltage VB. In this way, the power consumption of the feedback circuit 130 is reduced. The efficiency of the power supply device 100 will increase due to the low power consumption of the feedback circuit 130 itself.

[0043] In the present embodiment, the voltage value of the feedback voltage VF is associated with the voltage value of the output voltage VO. In addition, the compensation signal SC is associated with the voltage value of the feedback voltage VF. The controller 111 provides corresponding operations according to the compensation signal SC. For example, the controller 111 uses the control signal to control the primary side circuit 110. The higher the duty cycle of the control signal, the higher the voltage value of the output voltage VO. When the voltage value of the output voltage VO is higher, the voltage value of the feedback voltage VF is higher. The higher the value of the compensation signal SC. The value of the compensation signal SC can be a voltage value or a current value. The compensation signal SC can be a voltage signal or a current signal. Therefore, when the value of the compensation signal SC increases, the controller 111 will respond to the compensation signal SC and reduce the duty cycle of the control signal. On the other hand, when the voltage value of the output voltage VO is lower, the voltage value of the feedback voltage VF is lower. The value of the compensation signal SC is lower. When the value of the compensation signal SC decreases, the controller 111 increases the duty cycle of the control signal.

[0044] Please also refer to Figure 1 as well as Figure 2 , Figure 22 is a circuit diagram of a feedback circuit according to an embodiment of the present invention. In this embodiment, the feedback circuit 230 includes a feedback voltage generating circuit 231, a reference voltage generating circuit 232, and a compensation signal generating circuit 233. The feedback voltage generating circuit 231 includes a voltage dividing circuit 2311 and a semiconductor element 2312. The voltage dividing circuit 2311 divides the output voltage VO to generate a divided voltage VD. Therefore, the voltage value of the divided voltage VD is positively correlated with the voltage value of the output voltage VO. The semiconductor element 2312 generates a feedback voltage VF based on the bias voltage VB and the divided voltage VD. The voltage value of the feedback voltage VF is lower than the voltage value of the bias voltage VB.

[0045] In this embodiment, the first end of the semiconductor element 2312 receives the bias voltage VB. The second end of the semiconductor element 2312 is electrically connected to the reference voltage generating circuit 232. The control end of the semiconductor element 2312 receives the divided voltage VD. The semiconductor element 2312 is implemented by a bipolar junction transistor (BJT). Taking this embodiment as an example, the semiconductor element 2312 can be implemented by an NPN type BJT. Therefore, the voltage value of the feedback voltage VF at the second end of the semiconductor element 2312 is lower than the voltage value of the bias voltage VB at the first end of the semiconductor element 2312.

[0046] In the present embodiment, the voltage divider circuit 2311 includes voltage divider resistors RD1 and RD2. The first end of the voltage divider resistor RD1 receives the output voltage VO. The second end of the voltage divider resistor RD1 is electrically connected to the control end of the semiconductor element 2312. The voltage divider circuit 2311 provides a voltage divider voltage VD through the second end of the voltage divider resistor RD1. The first end of the voltage divider resistor RD2 receives the output voltage VO. The second end of the voltage divider resistor RD2 is electrically connected to the reference low voltage VSS2 of the secondary side circuit 120. The voltage divider circuit 2311 limits the voltage divider voltage VD within the range of the operating point of the semiconductor element 2312, so that the semiconductor element 2312 can operate.

[0047] In this embodiment, the voltage dividing resistors RD1 and RD2 are designed to have a higher resistance value, so the current value flowing through the voltage dividing resistors RD1 and RD2 will decrease. Therefore, the power consumption of the voltage dividing circuit 2311 will decrease.

[0048] In this embodiment, the reference voltage generating circuit 232 includes a voltage regulator 2321 and voltage regulator impedance circuits 2322 to 2324. The voltage regulator 2321 provides a reference voltage VFS from a first end of the voltage regulator 2321. The first end of the voltage regulator 2321 is electrically connected to the compensation signal generating circuit 233. The second end of the voltage regulator 2321 is electrically connected to the reference low voltage VSS2. The first end of the voltage regulator impedance circuit 2322 is electrically connected to the compensation signal generating circuit 233 and the second end of the semiconductor element 2312. The second end of the voltage regulator impedance circuit 2322 is electrically connected to the reference end of the voltage regulator 2321. The voltage regulator impedance circuit 2323 is electrically connected between the first end of the voltage regulator 2321 and the reference end of the voltage regulator 2321. The voltage regulator impedance circuit 2324 is electrically connected between the reference end of the voltage regulator 2321 and the second end of the voltage regulator 2321.

[0049] The voltage stabilizing impedance circuit 2322 is implemented by a resistor RS1. The voltage stabilizing impedance circuit 2324 is implemented by a resistor RS3. The voltage stabilizing impedance circuit 2323 is a resistor-capacitor circuit. The voltage stabilizing impedance circuit 2323 is implemented by a resistor RS2 and a capacitor C1 connected in series.

[0050] In this embodiment, the voltage regulator 2321 determines the reference voltage based on the voltage difference between the reference terminal of the voltage regulator 2321 and the second terminal of the voltage regulator 2321. Therefore, the reference voltage is fixed at a voltage value. For example, based on the operation of the voltage regulator 2321, the voltage value of the reference voltage is stabilized at 2.5 volts (but the present invention is not limited thereto). Taking this embodiment as an example, the voltage regulator 2321 can be implemented by a "TL431" component (but the present invention is not limited thereto).

[0051] In the present embodiment, the compensation signal generating circuit 233 generates a feedback voltage difference ΔVF according to the voltage value of the feedback voltage VF and the reference voltage VFS at the first end of the voltage regulator 2321, and generates a compensation signal SC according to the feedback voltage difference ΔVF. In the present embodiment, the feedback voltage difference ΔVF is positively correlated to the voltage difference between the voltage value of the feedback voltage VF and the voltage value of the reference voltage VFS. The controller 111 controls the primary side circuit 110 in response to the compensation signal SC. In the present embodiment, the compensation signal generating circuit 233 includes a light emitting element 2331 and a photodiode 2332. The anode of the light emitting element 2331 is electrically connected to the first end of the voltage stabilizing impedance circuit 2322. The cathode of the light emitting element 2331 is electrically connected to the first end of the voltage regulator 2321. The light emitting element 2331 provides a light signal L1 in response to the feedback voltage difference ΔVF.

[0052] A first end of the photodiode 2332 is electrically connected to the controller 111. A second end of the photodiode 2332 is electrically connected to a reference low voltage VSS1 of the primary circuit 110. A receiving end of the photodiode 2332 is used to receive the optical signal L1.

[0053] In the present embodiment, when the voltage value of the output voltage VO increases, the voltage value of the feedback voltage VF increases. The feedback voltage difference ΔVF also increases. The intensity of the light signal L1 is greater. This causes the current value of the compensation signal SC flowing through the first end of the photodiode 2332 and the second end of the photodiode 2332 to increase. Therefore, the controller 111 reduces the duty cycle of the control signal based on the current value of the compensation signal SC. When the voltage value of the output voltage VO decreases, the voltage value of the feedback voltage VF decreases. Therefore, the feedback voltage difference ΔVF also decreases. The intensity of the light signal L1 is smaller. This causes the current value of the compensation signal SC flowing through the first end of the photodiode 2332 and the second end of the photodiode 2332 to decrease. Therefore, the controller 111 increases the duty cycle of the control signal based on the current value of the compensation signal SC.

[0054] In some embodiments, the controller 111 may use the current value of the compensation signal SC as a charging current or a discharging current of an internal voltage. The controller 111 may increase or decrease the duty cycle of the control signal based on the charge change speed of the internal voltage.

[0055] In this embodiment, the feedback circuit 230 further includes resistors R1 and R2. The resistor R1 is electrically connected between the second end of the semiconductor element 2312 and the first end of the voltage-stabilizing impedance circuit 2322. The resistor R2 is electrically connected between the first end of the voltage-stabilizing impedance circuit 2322 and the anode of the light-emitting element 2331. The present invention is not limited thereto. In some embodiments, at least one of the resistors R1 and R2 may be omitted.

[0056] For example, the compensation signal generating circuit 233 may be implemented by a “PC817” component (but the present invention is not limited thereto).

[0057] In summary, the feedback circuit of the present invention includes a feedback voltage generating circuit. The feedback voltage generating circuit generates a feedback voltage based on a bias voltage and an output voltage. The voltage value of the feedback voltage is lower than the voltage value of the bias voltage. The voltage value of the feedback voltage changes with the change of the output voltage. The voltage value of the feedback voltage is limited to be lower than the voltage value of the bias voltage. In this way, the power consumption of the feedback circuit is reduced. The efficiency of the power supply device will increase due to the low power consumption of the feedback circuit itself.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A feedback circuit for a power supply device, characterized in that: The power supply device comprises a primary side circuit and a secondary side circuit, wherein the feedback circuit comprises: A feedback voltage generating circuit, electrically connected to the secondary side circuit, configured to receive a bias voltage and an output voltage of the power supply device, and to generate a feedback voltage according to the bias voltage and the output voltage; a reference voltage generating circuit, electrically connected to the feedback voltage generating circuit, and configured to provide a reference voltage according to the feedback voltage; and a compensation signal generating circuit, electrically connected to the feedback voltage generating circuit and the controller in the primary side circuit, configured to generate a compensation signal according to the feedback voltage and the reference voltage, and provide the compensation signal to the controller, wherein the voltage value of the feedback voltage is lower than the voltage value of the bias voltage, and The voltage value of the feedback voltage changes with the variation of the output voltage.

2. The feedback circuit according to claim 1, characterized in that: The feedback voltage generating circuit comprises: A voltage dividing circuit configured to divide the output voltage to generate a divided voltage; and A semiconductor element, wherein a first end of the semiconductor element receives the bias voltage, a second end of the semiconductor element is electrically connected to the reference voltage generating circuit, and a control end of the semiconductor element receives the divided voltage.

3. The feedback circuit according to claim 2, characterized in that: The voltage divider circuit comprises: a first voltage-dividing resistor, a first end of which receives the output voltage, and a second end of which is electrically connected to a control end of the semiconductor element; and A second voltage-dividing resistor, wherein a first end of the second voltage-dividing resistor receives the output voltage, and a second end of the second voltage-dividing resistor is electrically connected to a reference low voltage of the secondary-side circuit.

4. The feedback circuit according to claim 2, characterized in that: The semiconductor element is implemented by a bipolar junction transistor.

5. The feedback circuit according to claim 2, characterized in that: The reference voltage generating circuit comprises: A voltage stabilizer, wherein a first terminal of the voltage stabilizer is electrically connected to the compensation signal generating circuit, and a second terminal of the voltage stabilizer is electrically connected to a reference low voltage of the secondary side circuit; a first voltage-stabilizing impedance circuit, wherein a first end of the first voltage-stabilizing impedance circuit is electrically connected to the compensation signal generating circuit and a second end of the semiconductor element, and a second end of the first voltage-stabilizing impedance circuit is electrically connected between reference ends of the voltage regulator; a second voltage-stabilizing impedance circuit, the second voltage-stabilizing impedance circuit being electrically connected between the first terminal of the voltage regulator and a reference terminal of the voltage regulator; and A third voltage-stabilizing impedance circuit is electrically connected between a reference end of the voltage regulator and a second end of the voltage regulator.

6. The feedback circuit according to claim 5, characterized in that: The first voltage-stabilizing impedance circuit and the third voltage-stabilizing impedance circuit are resistors respectively.

7. The feedback circuit according to claim 5, characterized in that: The second voltage-stabilizing impedance circuit is a resistor-capacitor circuit.

8. The feedback circuit according to claim 5, characterized in that: The voltage regulator provides the reference voltage through a first terminal of the voltage regulator.

9. The feedback circuit according to claim 5, characterized in that: The compensation signal generating circuit generates a feedback voltage difference according to the voltage value of the feedback voltage and the reference voltage, and generates the compensation signal according to the feedback voltage difference, and The controller controls the primary circuit in response to the compensation signal.

10. The feedback circuit according to claim 9, characterized in that: The compensation signal generating circuit comprises: a light emitting element, wherein an anode of the light emitting element is electrically connected to a first end of the first voltage stabilizing impedance circuit, and a cathode of the light emitting element is electrically connected to a first end of the voltage regulator, wherein the light emitting element provides an optical signal in response to the feedback voltage difference; and A photodiode, wherein a first end of the photodiode is electrically connected to the controller, a second end of the photodiode is electrically connected to a reference low voltage of the primary side circuit, and a receiving end of the photodiode is used to receive the optical signal.

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