Power supply device and household electrical appliance having same

Abstract

The utility model discloses a power supply device and a household appliance with the power supply device, the power supply device is provided with an output control circuit, the output control circuit is connected to an output pin of a power supply management chip, on-off of a transistor is controlled based on output of the output pin, and the output circuit is provided with a third divider resistor and the transistor. Whether the third divider resistor is connected in parallel to the two ends of the second divider resistor is controlled by the on-off state of the transistor. The output of the output pin is different in the standby state and the working state, and the on-off state of the transistor is changed, so that whether the third divider resistor is connected with the second divider resistor in parallel or not can be controlled. In a standby state, the third divider resistor and the second divider resistor are in disconnected connection, the divided voltage of the first divider resistor is reduced, and the voltage output by the power supply device is reduced, so that the electric energy consumed by the load in the standby state is reduced; meanwhile, the voltage of the power input pin of the power management chip is reduced, the electric energy consumed by the power management chip is reduced, and the standby power consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of household appliances, in particular to a power supply device and a household appliance having the same. BACKGROUND

[0002] In the modern household appliance industry, with the enhancement of consumers' awareness of energy saving and environmental protection, the energy consumption problem of household appliances, especially the standby power consumption, has become an important concern. Standby power consumption refers to the power consumed by the device in an inactive state. Standby power consumption usually occurs when the device is not completely turned off but still maintains a certain degree of functional preparation state, such as remote standby, time display, etc. The traditional power supply design still consumes a considerable amount of power in standby mode, which not only increases the electricity bill of the family, but also has a negative impact on global energy consumption.

[0003] In recent years, the household appliance industry has gradually realized the importance of low standby power consumption, and many countries and regions have also begun to formulate relevant energy efficiency standards and regulations, requiring household appliance products to have a standby power consumption not exceeding a certain limit. This has prompted enterprises to pay more attention to energy efficiency optimization in product design. In order to reduce the standby power consumption of household appliances, in related technologies, high-efficiency power management chips are used, or intelligent control algorithms are designed, and some use automatic power-off design to automatically cut off power when the device is not used for a long time. However, these ways of reducing standby power consumption still have some shortcomings in practical application, such as high cost, limited scope of application, etc.

[0004] Therefore, it is urgent to provide a new way to reduce the standby power consumption of household appliances. SUMMARY

[0005] In order to reduce the standby power consumption of household appliances, the present application provides a power supply device and a household appliance having the same.

[0006] In some embodiments of the present application, the power supply device includes a power management chip, a flyback transformer, an output circuit, and an output control circuit. The power management chip has a power input pin and an output pin; the flyback transformer has a primary winding and a secondary winding, and the primary winding is connected to the power input pin.

[0007] The output circuit includes a first voltage dividing resistor, a second voltage dividing resistor, a third voltage dividing resistor, and a transistor. The first end of the first voltage dividing resistor is connected to the secondary winding, the second voltage dividing resistor is connected between the second end of the first voltage dividing resistor and the ground terminal, the transistor is connected to the third voltage dividing resistor and the second voltage dividing resistor, and whether the third voltage dividing resistor is connected in parallel across the second voltage dividing resistor is controlled by the on-off state of the transistor. The output control circuit is connected between the output pin and the transistor, and is used to control the on-off of the transistor.

[0008] Thus, in the technical solution, the power supply device is provided with an output control circuit connected to the output pin of the power management chip, the on-off of the transistor is controlled based on the output of the output pin of the power management chip, the output circuit is provided with a third voltage dividing resistor and the transistor, whether the third voltage dividing resistor is connected in parallel with the second voltage dividing resistor is controlled by the on-off state of the transistor, the output of the output pin of the power management chip is different in the standby state and the working state, the on-off state of the transistor is thus changed, and therefore the third voltage dividing resistor can be controlled to be connected in parallel with the second voltage dividing resistor or disconnected from the second voltage dividing resistor. When the third voltage dividing resistor is disconnected from the second voltage dividing resistor, the voltage division of the first voltage dividing resistor is reduced, the voltage output by the power supply device is reduced, and thus the power consumed by the load in the standby state is reduced; at the same time, the voltage input to the power input pin of the power management chip is reduced, and thus the power consumed by the power management chip in the standby state is reduced. Therefore, the standby power consumption of the household appliance can be reduced.

[0009] In some embodiments of the present application, the output pin is used to output a PWM wave, the output control circuit includes an on-off control element and a filter current limiting circuit, wherein the on-off control element is connected to the transistor and is configured to control the on-off of the transistor; the filter current limiting circuit is connected between the output pin and the on-off control element, and limits the voltage provided to the on-off control element based on the PWM wave output by the output pin, so as to control the on-off control element to turn on or turn off the transistor.

[0010] In the technical solution, the output control circuit is provided with an on-off control element, the on-off of the transistor is controlled through the on-off control element, a filter current limiting circuit is provided, and the filter current limiting circuit is used to control the on-off control element to turn on or turn off the transistor, and the filter current limiting circuit can ensure the normal operation of the on-off control element and avoid damage to the on-off control element caused by excessive current flowing through the on-off control element.

[0011] In some embodiments of the present application, the on-off control element is an optoelectronic coupler, which has a light-emitting diode and a photosensitive triode, the light-emitting diode of the on-off control element is connected between the filter current limiting circuit and the ground terminal, and the photosensitive triode of the on-off control element is connected between the control terminal of the transistor and the ground terminal.

[0012] In the technical solution, the optoelectronic coupler is used as the on-off control element, signal transmission is fast, and the anti-interference ability is strong.

[0013] In some embodiments of the present application, the filter current limiting circuit includes a first resistor, a second resistor and a first capacitor, the first end of the first resistor is connected to the output pin, the second end of the first resistor is connected to the first end of the second resistor and the first end of the first capacitor, the second end of the second resistor is connected to the anode of the light-emitting diode of the on-off control element, and the second end of the first capacitor is grounded.

[0014] In the technical solution, the filter current limiting circuit is composed of two resistors and one capacitor, and has simple structure and low cost.

[0015] In some embodiments of the present application, the transistor has a control terminal, a first terminal and a second terminal, the control terminal of the transistor is connected to the first terminal of the first voltage dividing resistor through the first pull-up resistor, the second voltage dividing resistor is connected between the first terminal of the transistor and the ground terminal, and the third voltage dividing resistor is connected between the second terminal of the transistor and the ground terminal.

[0016] In some embodiments of the present application, the power supply device further comprises a reference source connected to the transistor for providing a reference voltage to the transistor.

[0017] In the technical solution, the power supply device is provided with a reference source, and the transistor is provided with a stable reference voltage through the reference source, so that the transistor can be normally turned on or turned off.

[0018] In some embodiments of the present application, the power management chip has an error amplifier compensation pin and a ground pin, the ground pin is connected to the ground terminal, and the power supply device further comprises a first optoelectronic coupler and a three-terminal adjustable reference voltage source. The first optoelectronic coupler has a light-emitting diode and a photosensitive triode, the anode of the light-emitting diode of the first optoelectronic coupler is connected to the first terminal of the first voltage dividing resistor through the second pull-up resistor, the cathode of the light-emitting diode of the first optoelectronic coupler is connected to the second terminal of the first voltage dividing resistor through the second capacitor, one end of the photosensitive triode of the first optoelectronic coupler is connected to the error amplifier compensation pin, and the other end is connected to the ground pin; the three-terminal adjustable reference voltage source has an anode pin, a cathode pin and a voltage reference pin, the anode pin is grounded, the cathode pin is connected to one end of the second capacitor and the cathode of the light-emitting diode of the first optoelectronic coupler, and the voltage reference pin is connected to the first terminal of the transistor for providing a reference voltage to the transistor.

[0019] In the technical solution, the power supply device is a flyback power supply, and stable voltage output is realized through feedback voltage regulation.

[0020] In some embodiments of the present application, a household appliance is provided, which comprises the aforementioned power supply device.

[0021] In this way, the household appliance in the technical solution consumes less electric energy in the standby state, and the voltage of the power input pin of the power management chip is reduced, so that the power management chip consumes less electric energy in the standby state. Low standby power consumption is realized.

[0022] In some embodiments of the present application, the household appliance further comprises a controller and a voltage conversion device, the voltage conversion device is connected between the output terminal of the power supply device and the controller, and is used for converting the first voltage output by the power supply device into a second voltage and outputting the second voltage to the controller.

[0023] In the technical solution, the voltage conversion device is arranged to convert the first voltage output by the power supply device into a second voltage and output to the controller, so that the power supply voltage required by the controller can be better met.

[0024] In some embodiments of the present application, the voltage conversion device is a low dropout linear regulator or a direct current-direct current converter.

[0025] In the technical solution, the voltage conversion device is a low dropout linear regulator, which has small output ripple, low power consumption and low cost. The voltage conversion device is a direct current-direct current converter, which can realize input-output isolation, low power consumption and high efficiency.

[0026] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0028] Figure 1 A block diagram of a household appliance according to an embodiment of the present application is shown.

[0029] Figure 2 A block diagram of a household appliance according to another embodiment of the present application is shown.

[0030] Figure 3 A circuit schematic diagram of a power supply device according to an embodiment of the present application is shown.

[0031] Figure 4 A circuit schematic diagram of a household appliance according to an embodiment of the present application is shown.

[0032] The reference signs are explained as follows:

[0033] 100, household appliance; 10, controller; 20, load; 30, power supply device; 31, output circuit; 32, output control circuit; 40, voltage conversion device. DETAILED DESCRIPTION

[0034] In order to make the purpose, implementation and advantages of the present application clearer, the following will describe the exemplary embodiments of the present application clearly and completely with reference to the accompanying drawings of the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0035] It should be noted that the brief description of the terms in the present application is only for the convenience of understanding the embodiments described next, and is not intended to limit the embodiments of the present application. Unless otherwise specified, these terms should be understood according to their ordinary and general meanings.

[0036] In addition, the terms "comprising" and "having" and any variations thereof are intended to cover, but not exclusively, inclusion, for example, a product or device including a series of components does not have to be limited to those components clearly listed, but can include other components that are not clearly listed or inherent to these products or devices.

[0037] The terms "first", "second", "third" and the like ordinal numbers are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third" and the like ordinal numbers can explicitly or implicitly include one or more of the features.

[0038] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium; it can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] The technical problem of high standby power consumption exists in the related art household appliances, which is caused by the fact that the voltage output by the power supply device in standby state is the same as that in normal working state, which continuously supplies power to the loads of the household appliances in sleep state, such as relays, fans, etc., resulting in power consumption; and the supply voltage provided to the power management chip of the power supply device is the same as that in normal working state, which results in the power management chip consuming more power in standby state. Ultimately, it leads to high standby power consumption of the household appliances.

[0040] In standby state, the power consumption of the power supply device part is mainly composed of three parts: first, the load carried by the power supply device output, second, the self-loss of the power management chip, including the loss of the internal control circuit and the driving circuit of the chip, and third, the switching loss generated by the switching action of the main switch tube Q2.

[0041] The self-loss of the power management chip includes the loss of the internal control circuit and the driving circuit of the chip, which is related to the VCC voltage. Reducing the VCC voltage can reduce the self-loss of the power management chip. The loss of the driving circuit is caused by the charging and discharging of the parasitic capacitor of the gate of the switch tube Q2 connected to the power management chip. The value of the loss is determined by the product of Qg of the switch tube Q2, the VCC voltage and the switching frequency, that is, the loss is proportional to the VCC voltage.

[0042] Therefore, the power supply device of the embodiment of the present application is provided with an output control circuit connected to the output pin of the power management chip. The output control circuit controls the on-off of the transistor based on the output of the output pin of the power management chip. The output circuit is provided with a third voltage dividing resistor and the transistor. Whether the third voltage dividing resistor is connected in parallel with the second voltage dividing resistor is controlled by the on-off state of the transistor. Since the output of the output pin of the power management chip is different in the standby state and the working state, the on-off state of the transistor is changed, so that the third voltage dividing resistor can be connected in parallel with the second voltage dividing resistor or disconnected from the second voltage dividing resistor. In the standby state, the third voltage dividing resistor is disconnected from the second voltage dividing resistor, and the voltage dividing of the first voltage dividing resistor is reduced, so that the voltage output by the power supply device is reduced, thereby reducing the power consumed by the load in the standby state. At the same time, the voltage input to the power input pin of the power management chip is reduced, thereby reducing the power consumed by the power management chip in the standby state. Therefore, the standby power consumption of the household appliance can be reduced.

[0043] The household appliance of the embodiment of the present application can be any household appliance with a power supply device, such as a clothes dryer, a washing machine, an air conditioner, a refrigerator, etc.

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] Figure 1 The composition block diagram of the household appliance of one embodiment of the present application is shown.

[0046] As shown in Figure 1 The household appliance 100 of the embodiment of the present application includes a controller 10, a load 20 and a power supply device 30.

[0047] The controller 10 is connected to the power supply 30 to obtain the electrical energy required for operation from the power supply 30. The controller 10 may be a microcontroller unit (MCU). Of course, the controller 10 may also be other types of controllers, and this embodiment of the application does not limit this.

[0048] Load 20 is connected to power supply 30 to obtain the electrical energy required for operation from power supply 30. There can be multiple loads 20, and the number and type of loads 20 can vary depending on the specific type of household appliance 100. For example, load 20 can be a relay, fan, display, etc.

[0049] The load 20 can also be connected to the controller 10, which controls the start and stop of the load 20. For example, when the home appliance 100 is in normal working condition, the controller 10 sends a control signal to the load 20 to start working; when the home appliance 100 enters standby state, the controller 10 sends a control signal to the load 20 to stop working.

[0050] As previously described, the power supply unit 30 connects the controller 10 and the load 20 to provide the controller 10 and the load 20 with the electrical energy required for their operation.

[0051] Figure 2 A block diagram of a household appliance according to another embodiment of this application is shown.

[0052] like Figure 2 As shown, in some embodiments, the home appliance 100 may also include a voltage conversion device 40, which is connected between the output terminal of the power supply device 30 and the controller 10, for converting the first voltage output by the power supply device 30 into a second voltage and outputting it to the controller 10.

[0053] In some embodiments, the voltage conversion device 40 is a low dropout regulator (LDO). When the voltage input to the output terminal of the power supply device 30 or the current of the controller 10 changes, the LDO can still maintain a stable voltage output with low output ripple, low power consumption, and low cost.

[0054] In some embodiments, the voltage conversion device 40 is a DC-DC converter. DC-DC converters can achieve input-output isolation and have low power consumption and high efficiency.

[0055] In some embodiments, the first voltage is greater than the second voltage. Since the power supply device 30 outputs different voltages in the working state and the standby state, that is, the first voltage can represent different voltages in different states of the household appliance 100. For example, when the household appliance 100 is in the working state, the first voltage is 12V and the second voltage is 5V; when the household appliance 100 is in the standby state, the first voltage is 7V and the second voltage is 5V.

[0056] Figure 3 A circuit schematic diagram of the power supply device of one embodiment of the present application is shown.

[0057] As Figure 3 shown, in some embodiments, the power supply device 30 includes a power management chip N1, which has a power input pin VCC, an output pin DRV, an error amplifier compensation pin COM P, and a ground pin GND.

[0058] The power input pin VCC is used to receive a power supply input to enable the power management chip N1 to work. The output pin DRV is used to output a PWM wave. The duty cycle of the PWM wave output by the output pin DRV is different in the working state and the standby state. Specifically, in the working state, the PWM wave output by the output pin DRV has a larger duty cycle, and in the standby state, the PWM wave output by the output pin DRV has a smaller duty cycle. The ground pin GND is connected to the ground.

[0059] Of course, the power management chip N1 can also have other pins to meet the power management needs. For example, the power management chip N1 can use a chip of the UC3842 series. The present application does not describe the power management chip N1 in detail.

[0060] In some embodiments, the power supply device 30 can include a flyback transformer T1, which has a primary winding (not shown in the figure) and a secondary winding (not shown in the figure). The primary winding of the flyback transformer T1 is connected to the power input pin VCC of the power management chip N1, and the secondary winding of the flyback transformer T1 is connected to the output circuit as an output. When the voltage of the secondary winding of the flyback transformer T1 changes, the voltage of the primary winding of the flyback transformer T1 changes accordingly, thereby changing the voltage of the power input pin VCC of the power management chip N1, and further changing the energy consumption of the power management chip N1.

[0061] The specific composition of the flyback transformer T1 is known in the art and will not be described here.

[0062] In some embodiments, the power supply device 30 can include an output circuit 31, which includes a first voltage dividing resistor R1, a second voltage dividing resistor R2, a third voltage dividing resistor R3, and a transistor Q1. The first end of the first voltage dividing resistor R1 is connected to the secondary winding of the flyback transformer T1, the second voltage dividing resistor R2 is connected between the second end of the first voltage dividing resistor R1 and the ground, the first end of the third voltage dividing resistor R3 is connected to the transistor Q1, the second end of the third voltage dividing resistor R3 is grounded, and the transistor Q1 is also connected to the second voltage dividing resistor R2. The third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2, or disconnected from the second voltage dividing resistor R2, by the transistor Q1.

[0063] In detail, whether the third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2 is controlled by the on-off state of the transistor Q1. When the transistor Q1 is on, the third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2, and when the transistor Q1 is off, the third voltage dividing resistor R3 is disconnected from the second voltage dividing resistor R2.

[0064] In detail, whether the third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2 is controlled by the on-off state of the transistor Q1. When the transistor Q1 is on, the third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2, and when the transistor Q1 is off, the third voltage dividing resistor R3 is disconnected from the second voltage dividing resistor R2.

[0065] In detail, the transistor Q1 has a control end, a first end, and a second end. The control end of the transistor Q1 is connected to the first end of the first voltage dividing resistor R1 through a first pull-up resistor R4, the second voltage dividing resistor R2 is connected between the first end and the ground of the transistor Q1, and the third voltage dividing resistor R3 is connected between the second end and the ground of the transistor Q1.

[0066] In Figure 3 In the embodiment shown, the transistor Q1 is a P-type metal-oxide-semiconductor field-effect transistor (MOS transistor), the control end of the transistor Q1 is the gate of the transistor Q1, the first end of the transistor Q1 is the source of the transistor Q1, and the second end of the transistor Q1 is the drain of the transistor Q1. Of course, in other embodiments, the transistor Q1 can also be an N-type field-effect transistor, and the connection relationship between the transistor Q1 and other devices is changed accordingly; or other transistors, such as a triode, can be used.

[0067] It can be understood that the power supply device 30 can also include a reference source connected to the source of the transistor Q1 to provide a reference voltage to the transistor Q1, so that the on-off control of the transistor Q1 can be achieved.

[0068] In some embodiments, the power supply device 30 can include an output control circuit 32 connected between the output pin DRV of the power management chip N1 and the transistor Q1, for controlling the on-off of the transistor Q1.

[0069] In detail, when the household appliance 100 is in the working state, the PWM wave output by the output pin DRV of the power management chip N1 can enable the output control circuit 32 to control the transistor Q1 to be turned on; when the household appliance 100 is in the standby state, the PWM wave output by the output pin DRV of the power management chip N1 can enable the output control circuit 32 to control the transistor Q1 to be turned off. Thus, whether the third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2 can be controlled, so as to change the voltage division of the first voltage dividing resistor R1, and then the voltage output by the power supply device 30 is changed.

[0070] As shown in FIG. 2, in some embodiments, the output control circuit 32 includes an on-off control element O1 and a filter current limiting circuit. Figure 3

[0071] The on-off control element O1 is connected to the transistor Q1 and is configured to control the on-off of the transistor Q1.

[0072] In some embodiments, the on-off control element O1 is an optocoupler, which has a light-emitting diode and a photosensitive triode. The light-emitting diode of the on-off control element O1 is connected between the filter current limiting circuit and the ground, and the photosensitive triode of the on-off control element O1 is connected between the control terminal of the transistor Q1 and the ground.

[0073] The filter current limiting circuit is connected between the output pin DRV of the power management chip N1 and the on-off control element O1, and limits the voltage provided to the on-off control element O1 based on the PWM wave output by the output pin DRV of the power management chip N1, so as to control the on-off control element O1 to turn on or turn off the transistor Q1.

[0074] In detail, when the household appliance 100 is in the working state, the PWM wave output by the output pin DRV of the power management chip N1 is continuous and has a certain duty cycle. The filter current limiting circuit drives the light-emitting diode of the on-off control element O1 to be turned on, and the photosensitive triode of the on-off control element O1 has a current passing through, so as to lower the voltage at the control terminal of the transistor Q1 and turn on the transistor Q1. At this time, the third voltage dividing resistor R3 is connected in parallel across the second voltage dividing resistor R2. Since the resistance value after being connected in parallel is reduced, the voltage division of the first voltage dividing resistor R1 is increased, so that the power supply device 30 outputs a larger first voltage. At the same time, the voltage induced by the primary winding of the flyback transformer T1 is larger, that is, the voltage of the power input pin VCC of the power management chip N1 is larger, so as to meet the voltage requirement for the normal working of the power management chip N1.​

[0075] When the household appliance 100 is in standby state, the output pin DRV of the power management chip N1 has frequency hopping or the duty cycle of the output PWM wave is very low, and the voltage filtered by the filtering current limiting circuit is not enough to turn on the light-emitting diode of the on-off control element O1, and the photo triode of the on-off control element O1 is also in the off state, the voltage at the control end of the transistor Q1 is pulled up to the voltage output by the power supply device 30 by the first pull-up resistor R4, so that the transistor Q1 is turned off, and at this time the third voltage dividing resistor R3 is disconnected with the second voltage dividing resistor R2. Because of the voltage division of the second voltage dividing resistor R2 and the first voltage dividing resistor R1, the voltage division of the first voltage dividing resistor R1 is small, so the power supply device 30 outputs a smaller first voltage, and at the same time, the voltage induced by the primary winding of the flyback transformer T1 is small, that is, the voltage input to the power supply input pin VCC of the power management chip N1 is small, so as to reduce the power consumption of the power management chip N1 in standby state.

[0076] As shown in Figure 3 some embodiments, the filtering current limiting circuit includes a first resistor R5, a second resistor R6 and a first capacitor C1, the first end of the first resistor R5 is connected to the output pin DRV of the power management chip N1, the second end of the first resistor R5 is connected to the first end of the second resistor R6 and the first end of the first capacitor C1, the second end of the second resistor R6 is connected to the anode of the light-emitting diode of the on-off control element O1, and the second end of the first capacitor C1 and the cathode of the light-emitting diode of the on-off control element O1 are grounded.

[0077] In the above embodiment, the filtering current limiting circuit is composed of two resistors and a capacitor, which has simple structure and low cost.

[0078] As shown in Figure 3 some embodiments, the power supply device 30 further includes a first optocoupler O2 and a three-terminal adjustable reference voltage source N2.

[0079] The first optocoupler O2 has a light-emitting diode and a photo triode, the anode of the light-emitting diode of the first optocoupler O2 is connected to the first end of the first voltage dividing resistor R1 through a second pull-up resistor R7, the cathode of the light-emitting diode of the first optocoupler O2 is connected to the second end of the first voltage dividing resistor R1 through a second capacitor C2, one end of the photo triode of the first optocoupler O2 is connected to the compensation pin COMP of the error amplifier of the power management chip N1, and one end is connected to the ground pin GND of the power management chip N1. The second pull-up resistor R7 is used to set the current through the light-emitting diode of the first optocoupler O2.

[0080] The three-terminal adjustable reference voltage source N2 has an anode pin, a cathode pin, and a voltage reference pin. The anode pin of the three-terminal adjustable reference voltage source N2 is grounded. The cathode pin of the three-terminal adjustable reference voltage source N2 is connected to one end of the second capacitor C2 that is connected to the cathode of the light-emitting diode of the first optocoupler O2. The voltage reference pin of the three-terminal adjustable reference voltage source N2 is connected to the first end of the transistor Q1 to provide a reference voltage to the transistor Q1.

[0081] Of course, the three-terminal adjustable reference voltage source N2 can also have other pins to meet the requirements of the reference voltage source. For example, the three-terminal adjustable reference voltage source N2 can be a TL431. This application does not provide a detailed description of the three-terminal adjustable reference voltage source N2.

[0082] like Figure 3 As shown, the power supply device 30 of this application is a flyback power supply. Linear optocouplers are only suitable for transmitting low-frequency signals and generate significant transmission errors during transmission. To eliminate the transmission error of the optocoupler, the error amplifier of the three-terminal adjustable reference voltage source N2 is placed on the input side of the first optocoupler O2. Once the output voltage of the power supply device 30 is too high, the reference voltage of the three-terminal adjustable reference voltage source N2 increases slightly, which is equivalent to an increase in the voltage at the inverting input of the operational amplifier. The cathode of the three-terminal adjustable reference voltage source N2 is equivalent to the output of the operational amplifier, and its voltage will decrease. The current flowing through the light-emitting diode of the first optocoupler O2 increases, and the current of the transistor in the first optocoupler O2 also increases. Therefore, the voltage at the COM P compensation pin of the error amplifier of the power management chip N1 decreases, the voltage at the inverting input of the comparator inside the power management chip N1 decreases, the duty cycle decreases, and the output voltage decreases, thereby achieving the regulation of the entire feedback voltage.

[0083] Below, with Figure 3 The working principle of the power supply device 30 of this application will be explained using the illustrated embodiment as an example.

[0084] like Figure 3 As shown, the power supply device 30 of this application is equipped with a first resistor R5, a second resistor R6 and a first capacitor C1 to perform voltage division and filtering on the output pin DRV of the power management chip N1, and is equipped with an optocoupler O1, a transistor Q1 and a third voltage divider resistor R3 to control the secondary feedback, and the resistance values ​​of the second voltage divider resistor R2 and the third voltage divider resistor R3 are reasonably set.

[0085] The voltage of the output pin DRV of the power management chip N1 is affected by the load condition. In the standby state (light load), the output pin DRV of the power management chip N1 has frequency hopping or a very low duty cycle of the output PWM wave. In the normal working state, the duty cycle of the output PWM wave is high. The average voltage of the output pin DRV of the power management chip N1 can determine the load condition, that is, whether the current is in the standby state.

[0086] As described above, in the normal working state of the power supply device 30, the PWM wave output by the output pin DRV of the power management chip N1 is continuous and has a certain duty cycle. The filter current limiting circuit composed of the first resistor R5, the second resistor R6 and the first capacitor C1 drives the primary light emitting diode of the optocoupler O1 to be turned on. The secondary light-dependent triode has a current flowing through it, so that the gate of the secondary transistor Q1 is pulled to a voltage of 1V (based on the characteristics of the optocoupler O1 itself) to ground. The source of the transistor Q1 is connected to the reference voltage of the three-terminal adjustable reference voltage source N2, which is fixed at 2.5V (based on the characteristics of the three-terminal adjustable reference voltage source N2 itself). At this time, the voltage between the GS of the transistor Q1 is -1.5V, the transistor Q1 is turned on, and the resistance ratio of the second voltage dividing resistor R2 and the third voltage dividing resistor R3 in parallel is 1:0.265 to the resistance ratio of the first voltage dividing resistor R1. The output voltage of the power supply device 30 is kept at 12V, that is, the upper end voltage of the first voltage dividing resistor R1 is 12V. According to the winding ratio of the flyback transformer T1, the VCC voltage induced in the primary winding is 16V, which ensures the normal working of the power management chip N1.

[0087] In the light load state (standby state) of the power supply device 30, the output pin DRV of the power management chip N1 has frequency hopping or a very low duty cycle of the output PWM wave. The voltage after filtering by the first resistor R5, the second resistor R6 and the first capacitor C1 is not enough to turn on the light emitting diode inside the optocoupler O1. The secondary light-dependent triode is also in the cut-off state. The gate voltage of the transistor Q1 is pulled up to the output voltage of the power supply device 30 by the first pull-up resistor R4, that is, the upper end voltage of the first voltage dividing resistor R1. The source of the transistor Q1 is still stable at 2.5V. The gate-source voltage of the transistor Q1 is positive, and the transistor Q1 is cut off. At this time, the output circuit 31 only has the first voltage dividing resistor R1 and the second voltage dividing resistor R2. The resistance ratio of the first voltage dividing resistor R1 and the second voltage dividing resistor R2 is 1:0.556. The output voltage of the power supply device 30 is reduced to about 7V. According to the winding ratio of the flyback transformer T1, the VCC voltage induced in the primary winding is reduced to about 9V.

[0088] In the light-load state (standby state) of the power supply device 30, if the load is increased, the duty cycle of the PWM wave output by the output pin DRV of the power management chip N1 increases, the optocoupler O1 and the transistor Q1 are turned on again, the output voltage of the power supply device 30 automatically increases to 12V, and the corresponding VCC voltage of the power management chip N1 also increases to 16V, so that the power management chip N1 can work normally.

[0089] The supply current of a typical power management chip is between 2N and 4mA (the sum of the chip's own current consumption and the average drive current). In standby mode, its VCC voltage drops from 16V to 9V, corresponding to a power consumption reduction of 14N 28mW. Considering that the power efficiency in standby mode is only 50%, the input active power consumption of the power supply device 30 in this application can be reduced by 28-56mW.

[0090] If the input voltage of controller 10 is 5V, and if the 5V of controller 10 is provided via an LDO (e.g.) Figure 4 As shown in the figure, the power supply device 30 of this application will have a more significant effect on reducing standby power consumption. Considering that the 5V consumes 5mA of current in standby mode, reducing the output voltage of the power supply device 30 from 12V to 7V can ensure the normal output of the LDO, but the power consumption of the output section will be reduced from 60mW to 35mW, saving 25mW. Considering power efficiency, the reduction in standby power consumption will further increase from the aforementioned 28-56mW to 78-106mW.

[0091] In summary, the design of the power supply device 30 in this application increases the voltage divider resistor of the output circuit 31 in the standby state, thereby reducing the output voltage of the power supply device 30 and the VCC voltage of the power management chip N1 in the standby state. This reduces the self-loss of the power management chip N1 in the standby state and the power consumption of the peripheral load 20, thereby reducing the standby power consumption of the home appliance 100.

[0092] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of this application is limited only by the appended claims.

Claims

1. A power supply device characterized by comprising: The power supply device comprises: a power management chip having a power input pin and an output pin; a flyback transformer having a primary winding and a secondary winding, the primary winding being connected to the power input pin; an output circuit comprising a first voltage dividing resistor, a second voltage dividing resistor, a third voltage dividing resistor and a transistor, a first end of the first voltage dividing resistor being connected to the secondary winding, the second voltage dividing resistor being connected between a second end of the first voltage dividing resistor and a ground terminal, a first end of the third voltage dividing resistor being connected to the transistor, a second end of the third voltage dividing resistor being grounded, the transistor further being connected to the second voltage dividing resistor, whether the third voltage dividing resistor is connected in parallel across the second voltage dividing resistor being controlled by a turn-on / off state of the transistor; an output control circuit connected between the output pin and the transistor, for controlling the turn-on / off state of the transistor.

2. The power supply device according to claim 1, characterized by The output pin is used for outputting a PWM wave, and the output control circuit comprises: a turn-on / off control element connected to the transistor and configured to control the turn-on / off state of the transistor; a filter current limiting circuit connected between the output pin and the turn-on / off control element, for limiting a voltage provided to the turn-on / off control element based on the PWM wave output by the output pin, so as to control the turn-on / off control element to turn on or turn off the transistor.

3. The power supply device according to claim 2, characterized by The turn-on / off control element is an optoelectronic coupler having a light-emitting diode and a photosensitive triode, the light-emitting diode of the turn-on / off control element being connected between the filter current limiting circuit and a ground terminal, and the photosensitive triode of the turn-on / off control element being connected between a control terminal of the transistor and a ground terminal.

4. The power supply device according to claim 3, characterized by The filter current limiting circuit comprises a first resistor, a second resistor and a first capacitor, a first end of the first resistor being connected to the output pin, a second end of the first resistor being connected to a first end of the second resistor and a first end of the first capacitor, a second end of the second resistor being connected to an anode of the light-emitting diode of the turn-on / off control element, and a second end of the first capacitor being grounded.

5. The power supply device according to claim 1, wherein The transistor has a control terminal, a first end and a second end, the control terminal of the transistor being connected to the first end of the first voltage dividing resistor through a first pull-up resistor, the second voltage dividing resistor being connected between the first end of the transistor and a ground terminal, and the third voltage dividing resistor being connected between the second end of the transistor and a ground terminal.

6. The power supply device according to claim 1, wherein The power supply device further comprises a reference source connected to the transistor, for providing a reference voltage to the transistor.

7. The power supply device according to any one of claims 1 to 5, characterized by The power management chip has an error amplifier compensation pin and a ground pin, the ground pin being connected to a ground terminal, and the power supply device further comprises: a first optoelectronic coupler having a light-emitting diode and a photosensitive triode, an anode of the light-emitting diode of the first optoelectronic coupler being connected to the first end of the first voltage dividing resistor through a second pull-up resistor, a cathode of the light-emitting diode of the first optoelectronic coupler being connected to the second end of the first voltage dividing resistor through a second capacitor, one end of the photosensitive triode of the first optoelectronic coupler being connected to the error amplifier compensation pin, and one end being connected to the ground pin; A three-terminal adjustable reference voltage source has an anode pin, a cathode pin and a voltage reference pin, the anode pin is connected to ground, the cathode pin is connected to one end of the second capacitor and the cathode of the light emitting diode of the first optocoupler, the voltage reference pin is connected to the first end of the transistor for providing a reference voltage to the transistor.

8. An electric home appliance characterized by comprising: The household appliance comprises the power supply device according to any one of claims 1 to 7.

9. The home appliance of claim 8, wherein, The household appliance further comprises: a controller; a voltage conversion device connected between the output of the power supply device and the controller for converting the first voltage output by the power supply device to a second voltage output to the controller.

10. The home appliance of claim 9, wherein The voltage conversion device is a low dropout linear regulator or a DC-DC converter.

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