TWM654740U - Feedback circuit for power supply device - Google Patents

Abstract

A feedback circuit for a power supply device is provided. The power supply device includes a primary side circuit and a secondary side circuit. The feedback circuit includes a feedback voltage generating circuit, a base 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 generates the feedback voltage according to a bias voltage and an output voltage of the power supply device. The base voltage generating circuit generates a base voltage according to the feedback voltage. The compensation signal generating circuit generates a compensation signal according to the feedback voltage and the base voltage, and provides the compensation signal to a controller in the primary side circuit. A voltage value of the feedback voltage is lower than a voltage value of the bias voltage. The voltage value of the feedback voltage is varied with a variation of the output voltage.

Description

Feedback circuit for power supply device

This novel invention relates to a feedback circuit, and in particular to a feedback circuit for a power supply device.

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

However, when the power supply device is a boost circuit, the output voltage value 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 technical forecasters.

This novel invention provides a feedback circuit for a power supply device, which can reduce the power consumption of the feedback circuit.

The feedback circuit of the novel invention is used for a power supply device. The power supply device includes a primary circuit and a secondary 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 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 the controller in the primary 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 in the primary 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 with the change of the output voltage.

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.

100: Power supply device

110: Primary circuit

111: Controller

120: Secondary circuit

130, 230: Feedback circuit

131, 231: Feedback voltage generating circuit

132, 232: Reference voltage generating circuit

133, 233: Compensation signal generating circuit

2311: Voltage divider circuit

2312:Semiconductor components

2321: Voltage regulator

2322~2324: Voltage stabilizing impedance circuit

2331: Light-emitting element

2332: Photodiode

C1: Capacitor

R1, R2: resistors

RD1, RD2: voltage divider resistors

RS1~RS3: Resistors

SC: Compensation signal

TR: Transformer

VB: Bias voltage

VF: Feedback voltage

VFS: reference voltage

VIN: Input voltage

VO: output voltage

VR: conversion voltage

△VF: Feedback voltage difference

Figure 1 is a schematic diagram of a power supply device according to an embodiment of the present invention.

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

Some embodiments of the present invention will be described in detail with reference to the accompanying drawings. The component symbols used in the following description will be regarded as the same or similar components when the same component 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 precisely, these embodiments are only examples within the scope of the patent application of the present invention.

Please refer to Figure 1, which 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 circuit 110, a secondary circuit 120 and a feedback circuit 130. The primary 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 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 further includes a transformer TR (but the present invention is not limited thereto). The transformer TR is used to provide a conversion voltage VR. In this embodiment, the primary 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 circuit 110. The switching operation of the power transistor can determine the voltage value of the conversion voltage VR.

In this embodiment, the primary 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 responds to the compensation signal SC to provide a corresponding operation, thereby stabilizing the output voltage VO.

In this 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.

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

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.

In this embodiment, the voltage value of the feedback voltage VF is related to the voltage value of the output voltage VO. In addition, the compensation signal SC is related to 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 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 value of the compensation signal SC is higher. 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 lower the value of the compensation signal SC. When the value of the compensation signal SC decreases, the controller 111 increases the duty cycle of the control signal.

Please refer to FIG. 1 and FIG. 2 at the same time. FIG. 2 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 according to 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.

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.

In this 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 the 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 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, thereby enabling the semiconductor element 2312 to operate.

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

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.

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

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 to this). Taking this embodiment as an example, the voltage regulator 2321 can be implemented by a "TL431" component (but the present invention is not limited to this).

In the present embodiment, the compensation signal generating circuit 233 generates a feedback voltage difference △VF 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 △VF. In the present embodiment, the feedback voltage difference △VF 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 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 regulator 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 responds to the feedback voltage difference △VF to provide the optical signal L1.

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

In this embodiment, when the voltage value of the output voltage VO increases, the voltage value of the feedback voltage VF increases. The feedback voltage difference △VF will also increase. 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 will reduce 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 △VF will also decrease. The intensity of the light signal L1 is smaller. This reduces 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. Therefore, the controller 111 increases the duty cycle of the control signal based on the current value of the compensation signal SC.

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.

In this embodiment, the feedback circuit 230 also 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 to this. In some embodiments, at least one of the resistors R1 and R2 can be omitted.

For example, the compensation signal generating circuit 233 can be implemented by a "PC817" component (but the present invention is not limited to this).

In summary, the feedback circuit of the novel 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 a voltage value lower than the bias voltage. In this way, the power consumption of the feedback circuit is reduced. The efficiency of the power supply device is increased due to the low power consumption of the feedback circuit itself.

Although the novel creation has been disclosed as above by way of embodiments, it is not intended to limit the novel creation. Anyone with ordinary knowledge in the relevant technical field may make some changes and modifications within the spirit and scope of the novel creation. Therefore, the protection scope of the novel creation shall be subject to the scope of the patent application attached hereto.

100: Power supply device

110: Primary circuit

111: Controller

120: Secondary circuit

130: Feedback circuit

131: Feedback voltage generating circuit

132: Reference voltage generating circuit

133: Compensation signal generating circuit

SC: Compensation signal

TR: Transformer

VB: Bias voltage

VF: Feedback voltage

VFS: reference voltage

VIN: Input voltage

VO: output voltage

VR: conversion voltage

Claims (10)

A feedback circuit for a power supply device, wherein the power supply device includes a primary circuit and a secondary circuit, wherein the feedback circuit includes: a feedback voltage generating circuit, electrically connected to the secondary 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, configured to generate a feedback voltage according to the bias voltage and the output voltage; The feedback voltage is used to provide a reference voltage; and a compensation signal generating circuit is electrically connected to the feedback voltage generating circuit and the controller in the primary circuit, and is 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 wherein the voltage value of the feedback voltage changes with the change of the output voltage. A feedback circuit as described in claim 1, wherein the feedback voltage generating circuit comprises: a voltage divider 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. A feedback circuit as described in claim 2, wherein the voltage divider circuit comprises: a first voltage divider resistor, a first end of the first voltage divider resistor receives the output voltage, and a second end of the first voltage divider resistor is electrically connected to the control end of the semiconductor element; and a second voltage divider resistor, a first end of the second voltage divider resistor receives the output voltage, and a second end of the second voltage divider resistor is electrically connected to the reference low voltage of the secondary circuit. A feedback circuit as described in claim 2, wherein the semiconductor element is implemented by a bipolar junction transistor. The feedback circuit as claimed in claim 2, wherein the reference voltage generating circuit comprises: a voltage regulator, a first end of the voltage regulator is electrically connected to the compensation signal generating circuit, and a second end of the voltage regulator is electrically connected to the reference low voltage of the secondary circuit; a first voltage regulating impedance circuit, a first end of the first voltage regulating impedance circuit is electrically connected to the compensation signal generating circuit and the semiconductor element The second end of the first voltage regulator impedance circuit is electrically connected to the reference end of the voltage regulator; the second voltage regulator impedance circuit is electrically connected between the first end of the voltage regulator and the reference end of the voltage regulator; and the third voltage regulator impedance circuit is electrically connected between the reference end of the voltage regulator and the second end of the voltage regulator. A feedback circuit as described in claim 5, wherein the first voltage-stabilizing impedance circuit and the third voltage-stabilizing impedance circuit are resistors respectively. A feedback circuit as described in claim 5, wherein the second voltage-stabilizing impedance circuit is a resistor-capacitor circuit. A feedback circuit as described in claim 5, wherein the voltage regulator provides the reference voltage from the first end of the voltage regulator. A feedback circuit as described in claim 5, wherein: 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. The feedback circuit as described in claim 9, wherein the compensation signal generating circuit comprises: a light-emitting element, the anode of the light-emitting element is electrically connected to the first end of the first voltage-stabilizing impedance circuit, the cathode of the light-emitting element is electrically connected to the first end of the voltage regulator, wherein the light-emitting element provides a light signal in response to the feedback voltage difference; and a photodiode, the first end of the photodiode is electrically connected to the controller, the second end of the photodiode is electrically connected to the reference low voltage of the primary circuit, and the receiving end of the photodiode is used to receive the light signal.

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