Power switching circuit and power supply system

Abstract

The power supply switching circuit comprises a power supply circuit and a comparison circuit, the power supply circuit is connected with the comparison circuit and a load, the input end of the comparison circuit is connected with different power supplies, the comparison circuit compares the voltage of each power supply and determines the power supply for power supply, and the power supply for power supply is transmitted to the load through the power supply circuit. Voltage of each power supply is compared through a comparison circuit, power supply switching is carried out according to voltage logic, and the power supply for power supply is changed. The power supply switching process is smooth and reliable, and the stability of the multi-power-supply power supply switching process can be improved.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a power switching circuit and a power supply system. Background Art

[0002] Common electronic products are equipped with a single power supply or power adapter to power the electronic products through a single circuit. With the development of science and technology, the demand for electronic products has gradually diversified, and electronic products need to be able to adapt to different working environments. Among them, the stability of the power supply configuration is particularly important, and it is an important means to improve the applicability of electronic products.

[0003] At present, electronic products are usually equipped with built-in batteries that can be used without a power adapter, combined with an external power supply through a power adapter for power supply. On the basis of multi-power supply, it is also necessary to ensure the stability and reliability of the multi-power switching process to achieve stable operation of electronic products. How to ensure the stability and reliability of the multi-power switching process is still a problem that needs to be solved urgently. Utility Model Content

[0004] Based on this, it is necessary to provide a power switching circuit and a power supply system that can improve the stability of multi-power switching in order to solve the above technical problems.

[0005] In a first aspect, the present application provides a power switching circuit, which includes a power supply circuit and a comparison circuit, wherein the power supply circuit is connected to the comparison circuit and a load, and the input end of the comparison circuit is connected to different power supplies. The comparison circuit compares the voltages of each of the power supplies to determine the power supply, and the power supply is transmitted to the load through the power supply circuit.

[0006] In one embodiment, the comparison circuit includes a power supply guarantee circuit and a power supply selection circuit, the power supply guarantee circuit and the power supply selection circuit are connected to the power supply circuit, the power supply guarantee circuit is connected to the main power supply, and the power supply selection circuit is connected to the main power supply and the secondary power supply; the power supply selection circuit is used to compare the voltages of each connected power supply; the output power supply of the power supply selection circuit is compared with the output power supply of the power supply guarantee circuit to determine the power supply.

[0007] In one embodiment, the power supply selection circuit includes a comparison switch tube, the control end of the comparison switch tube is connected to the main power supply, the input end of the comparison switch tube is connected to the secondary power supply, and the output end of the comparison switch tube is connected to the common end of the power supply circuit and the power supply guarantee circuit.

[0008] In one of the embodiments, the power supply selection circuit further includes a voltage regulator tube, and the voltage regulator tube is arranged between the output end of the comparison switch tube and the power supply circuit.

[0009] In one embodiment, the power supply selection circuit further includes a voltage judgment circuit, an input end of the voltage judgment circuit is connected to a main power supply and a secondary power supply, and an output end of the voltage judgment circuit is connected to a control end of the comparison switch tube.

[0010] In one embodiment, the voltage judgment circuit includes a voltage detection switch tube and a judgment switch tube, the control end of the voltage detection switch tube is connected to the main power supply, the output end of the voltage detection switch tube is connected to the control end of the judgment switch tube, the input end of the voltage detection switch tube is grounded, the control end of the judgment switch tube is connected to the secondary power supply, the output end of the judgment switch tube is connected to the control end of the comparison switch tube, and the input end of the judgment switch tube is grounded.

[0011] In one embodiment, the power switching circuit also includes a control circuit and a host computer, the control circuit is connected to the power supply circuit and the host computer, the host computer outputs different levels for controlling the working state of the control circuit, and the working state of the control circuit is used to control the on and off of the power supply circuit.

[0012] In one embodiment, the power supply circuit includes a master control switch tube, a control end of the master control switch tube is connected to the control circuit, an input end of the master control switch tube is connected to the comparison circuit, and an output end of the master control switch tube is connected to the load.

[0013] In one embodiment, the power switching circuit further includes a startup circuit, and the startup circuit is connected to the host computer and each of the power supplies.

[0014] In a second aspect, the present application further provides a power supply system, which includes a power supply and a power switching circuit as described above, and the number of the power supplies is more than two.

[0015] The power switching circuit and power supply system include a power supply circuit and a comparison circuit. The power supply circuit is connected to the comparison circuit and the load. The input end of the comparison circuit is connected to different power supplies. The comparison circuit compares the voltages of each power supply to determine the power supply, and the power supply is transmitted to the load through the power supply circuit. The voltages of each power supply are compared by the comparison circuit, and the power supply is switched according to the voltage logic to change the power supply. The power supply switching process is smooth and reliable, which can improve the stability of the multi-power supply switching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is an application environment diagram of a power switching circuit in one embodiment;

[0017] FIG2 is a schematic diagram of the structure of a power switching circuit in one embodiment;

[0018] FIG3 is a schematic diagram of the structure of a power switching circuit in another embodiment;

[0019] FIG4 is a circuit diagram of a comparison circuit in one embodiment;

[0020] FIG5 is a circuit diagram of a comparison circuit in another embodiment;

[0021] FIG6 is a schematic diagram of a circuit for a startup circuit in one embodiment;

[0022] FIG. 7 is a circuit diagram of a power switching circuit in one embodiment. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0025] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0026] When used herein, the singular forms "a", "an" and " / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0028] The power switching circuit provided in the embodiment of the present application can be applied to the application environment as shown in Figure 1. The power switching circuit 102 is connected to different power sources, and the power energy of the power source is transmitted through the power switching circuit 102 to power the load. The power switching circuit 102 can select or switch multiple power sources to achieve flexible and reliable power supply of multiple power sources. Among them, the power source is an energy storage device or an energy transmission device. Exemplarily, the power source includes but is not limited to any one or more of a power grid, a battery, or a generator. The load can be various types of power-demanding equipment, which are too numerous to list here.

[0029] In one embodiment, as shown in Figure 2, the present application provides a power switching circuit 102, which includes a power supply circuit 204 and a comparison circuit 202. The power supply circuit 204 connects the comparison circuit 202 and the load. The input end of the comparison circuit 202 is connected to different power supplies. The comparison circuit 202 compares the voltages of each power supply to determine the power supply, and the power supply is transmitted to the load through the power supply circuit 204.

[0030] Specifically, the comparison circuit 202 is connected to different power supplies, and can compare the voltages of different power supplies to determine whether there is voltage in each power supply, or to determine the voltage between the power supplies. The comparison circuit 202 determines the power supply according to the comparison result, and outputs the power of the power supply to the power supply circuit 204. The power supply circuit 204 transmits the power of the power supply to the load, so that the power supply supplies power to the load.

[0031] In this embodiment, since the comparison circuit 202 relies on the voltage of each power supply to make a direct comparison and is not affected by software control, there is no need to wait for the software response during the power switching process, which has the advantage of instant switching. Optionally, the comparison circuit 202 can compare the voltages between different power supplies and can also switch the power supply of each power supply according to the power supply sequence in the actual needs of the staff. That is, the comparison circuit 202 can preferentially determine the power supply with a higher power supply priority or a larger voltage as the power supply, wherein the power supply priority can be the power supply sequence selected by the staff according to the actual needs.

[0032] In order to realize the power switching of the above-mentioned power supply priority and to ensure the stability of the power switching, in one embodiment, as shown in Figure 3, the comparison circuit 202 includes a power supply guarantee circuit 304 and a power supply selection circuit 302, the power supply guarantee circuit 304 and the power supply selection circuit 302 are connected to the power supply circuit 204, the power supply guarantee circuit 304 is connected to the main power supply, and the power supply selection circuit 302 is connected to the main power supply and the secondary power supply.

[0033] The main power source is the power source with the highest power supply priority selected by the staff, that is, the power source ranked first in the power supply sequence. Optionally, the main power source is the power source with the highest voltage among all the power sources. Correspondingly, the secondary power source is the power source with a lower power supply priority than the main power source selected by the staff, that is, the power source ranked after the first in the power supply sequence. Optionally, the voltage of the secondary power source is lower than that of the main power source. Similarly, the number of secondary power sources is not limited and can be one or more.

[0034] Specifically, the power supply guarantee circuit 304 is connected to the main power supply to ensure that when the main power supply has a power supply voltage or can provide the voltage required by the load, the comparison circuit 202 can determine that the power supply is the main power supply. The power supply selection circuit 302 is used to compare the voltages of the connected power supplies, which can be to compare the voltages of the power supplies and select the power supply with the largest voltage as the power supply. It can also be to compare whether the power supplies have voltages, and determine the output power supply of the power supply selection circuit 302 according to the power supply priority. Furthermore, the output power supply of the power supply selection circuit 302 is compared with the output power supply of the power supply guarantee circuit 304 to determine the power supply.

[0035] Optionally, the circuit structure of the power supply selection circuit 302 is not limited, and there are two situations: the first situation. The power supply selection circuit 302 selects the output power supply by comparing the voltage of each power supply. At this time, the output power supply of the power supply guarantee circuit 304 is the main power supply, and the output of the power supply selection circuit 302 may be the main power supply or the secondary power supply. If the output power supply of the power supply selection circuit 302 is the main power supply, the power supply determined to be the main power supply is the main power supply, and the main power supply completes the power supply to the load. If the output power supply of the power supply selection circuit 302 is the secondary power supply, the voltage of the output power supply of the power supply selection circuit 302 is less than the voltage of the output power supply of the power supply guarantee circuit 304 (the voltage of the secondary power supply is less than the voltage of the main power supply), then the power supply determined to be the main power supply is the main power supply, and the main power supply completes the power supply to the load. In this case, if the main power supply fails or the main power supply has no power, the output power supply (secondary power supply) of the power supply selection circuit 302 supplies power to the load.

[0036] In the second case, the power supply selection circuit 302 determines the output power supply by comparing whether there is voltage in each power supply and according to the power supply priority. At this time, the output power supply of the power supply guarantee circuit 304 is the main power supply, and the main power supply connected to the power supply selection circuit 302 is only used for voltage detection, then the output power supply of the power supply selection circuit 302 is the secondary power supply, and if there are multiple secondary power supplies, they may be different secondary power supplies. In the case where the main power supply has a supply voltage, since the voltage of the main power supply is greater than the secondary power supply, the main power supply output by the power supply guarantee circuit 304 is determined to be the power supply for power supply. In the case where there is no supply voltage in the main power supply, the output power supply of the power supply selection circuit 302 is the power supply for power supply.

[0037] The structure of the power supply selection circuit 302 is designed according to actual conditions. Taking the determination of the power supply according to the power supply priority as an example, in one embodiment, the power supply selection circuit 302 includes a comparison switch tube, the control end of the comparison switch tube is connected to the main power supply, the input end of the comparison switch tube is connected to the secondary power supply, and the output end of the comparison switch tube is connected to the common end of the power supply circuit 204 and the power supply guarantee circuit 304.

[0038] Specifically, the comparison switch tube is a PMOS tube, and the control end of the comparison switch tube is connected to the main power supply, and can sense the supply voltage of the main power supply. When the supply voltage of the main power supply exists, the comparison switch tube is cut off, and the secondary power supply connected to the input end of the comparison switch tube cannot be transmitted to the output end of the comparison switch tube, and the power supply selection circuit 302 does not have an output power supply, and determines that the power supply is the main power supply.

[0039] In order to stabilize the output of the power supply selection circuit 302, in one embodiment, the power supply selection circuit 302 further includes a voltage regulator tube, which is arranged between the output end of the comparison switch tube and the power supply circuit 204. The voltage regulator tube can be a voltage regulator switch tube, which has a strong anti-interference ability, can reduce the influence of interference signals, and ensure the stability and reliability of the output voltage.

[0040] Exemplarily, the power supply selection circuit 302 can be as shown in FIG4, the comparison switch tube is the switch tube Q7, VCC3 is the secondary power supply, VCC1 is the main power supply, the voltage regulator tube is the voltage regulator diode D6, POWER_BUS is the common end of the power supply circuit 204 and the power supply guarantee circuit 304, and the numbers 1-8 in the figure are the pin connections of the switch tube. VCC1 is connected to the control end of the switch tube Q7 through the resistor R12, and is connected to the pull-down resistor R14 and grounded through the resistor R12 to achieve control of the switch tube Q7. When VCC1 has no power supply voltage, the switch tube Q7 is turned on, and the electric energy of VCC3 can be transmitted to POWER_BUS through the switch tube Q7 and the voltage regulator diode D6. Among them, the switch tube Q7 is a PMOS tube, the model can be AO4409-MS, the model of the voltage regulator diode D6 can be SB1045, the resistance value of the resistor R12 can be 10K ohms, and the resistance value of R14 can be 100K ohms.

[0041] In this embodiment, the power switching circuit 102 includes a power supply circuit 204 and a comparison circuit 202, the power supply circuit 204 is connected to the comparison circuit 202 and the load, the input end of the comparison circuit 202 is connected to different power supplies, the comparison circuit 202 compares the voltages of each power supply to determine the power supply, and the power supply is transmitted to the load through the power supply circuit 204. The voltages of each power supply are compared by the comparison circuit 202, and the power supply is switched according to the voltage logic to change the power supply. The power supply switching process is smooth and reliable, which can improve the stability of the multi-power supply switching process.

[0042] The power supply selection circuit 302 may also be other circuit structures. In one embodiment, when the voltage magnitude relationship between the main power supply and the secondary power supply is not fixed and there is only a power supply priority order, the power supply selection circuit 302 may also include a voltage judgment circuit, the input end of the voltage judgment circuit is connected to the main power supply and the secondary power supply, and the output end of the voltage judgment circuit is connected to the control end of the comparison switch tube. It should be noted that when there are multiple secondary power supplies and each secondary power supply has a different power supply priority, since the main power supply is connected to the power supply guarantee circuit 304, the power supply selection circuit 302 may be connected to different secondary power supplies, and comparisons are made between different secondary power supplies to determine the output power of the power supply selection circuit 302. In the power supply selection circuit 302 that does not involve the main power supply, the secondary power supply with a higher power supply priority can be regarded as the main power supply to complete the power supply switching between the secondary power supplies.

[0043] Specifically, the voltage judgment circuit is used to judge whether there is a supply voltage in the main power supply. When there is no supply voltage in the main power supply, the output end of the voltage judgment circuit controls the comparison switch tube to turn on; when there is a supply switch tube in the main power supply, the output end of the voltage judgment circuit controls the comparison switch tube to turn off.

[0044] In one embodiment, the voltage judgment circuit includes a voltage detection switch tube and a judgment switch tube, the control end of the voltage detection switch tube is connected to the main power supply, the output end of the voltage detection switch tube is connected to the control end of the judgment switch tube, the input end of the voltage detection switch tube is grounded, the control end of the judgment switch tube is connected to the secondary power supply, the output end of the judgment switch tube is connected to the control end of the comparison switch tube, and the input end of the judgment switch tube is grounded.

[0045] Specifically, the voltage detection switch tube and the judgment switch tube are both PMOS tubes. The control end of the voltage detection switch tube is connected to the main power supply. When the power supply voltage of the main power supply exists, the control end of the voltage detection switch tube is pulled up by the power supply voltage of the main power supply, and the voltage detection switch tube is cut off. The control end of the judgment switch tube is connected to the secondary power supply and the output end of the voltage detection switch tube. When the voltage detection switch tube is cut off, the control end of the judgment switch tube is pulled up by the voltage of the secondary power supply, and the judgment switch tube is cut off. The state of the judgment switch tube is used to control the state of the comparison switch tube to achieve the selection of the output power supply.

[0046] Exemplarily, the power supply selection circuit 302 can be as shown in Figure 5, in which the comparison switch tube is the switch tube Q6, the voltage regulator tube is the voltage regulator diode D5, the voltage judgment circuit includes a voltage detection switch tube and a judgment switch tube, the voltage detection switch tube is the switch tube Q12, the judgment switch tube is the switch tube Q9, the main power supply (or the secondary power supply with a higher power supply priority) is VCC3, the secondary power supply (or the secondary power supply with a power supply priority) is VCC2, the numbers 1-8 represent pins, and POWER_BUS is the common end of the power supply circuit 204 and the power supply guarantee circuit 304.

[0047] When there is a supply voltage on VCC3, the supply voltage of VCC3 is divided by resistors R15 and R18 and then transferred to the control end of switch tube Q12, so that switch tube Q12 is turned off. When there is a supply voltage on VCC2, the supply voltage of VCC2 is divided by resistors R13 and R16 through the body diode of switch tube Q5 and then applied to the control end of switch tube Q9. When switch tube Q12 is in the off state, switch tube Q9 is turned off. Then the supply voltage of VCC2 is applied to the control end of switch tube Q6 through resistor R10, and switch tube Q6 is turned off, and the electric energy of VCC2 cannot be output. On the contrary, when there is no supply voltage on VCC3, switch tube Q12 is turned on, and the supply voltage of VCC2 is grounded through switch tube Q12 after passing through resistor R13, so as to lower the voltage of the control end of switch tube Q9. Then switch tube Q9 is turned on, and then the control end of switch tube Q6 is grounded through switch tube Q9, so switch tube Q6 and switch tube Q5 are turned on, so that the output of VCC2 can be realized.

[0048] Among them, the switch tube Q5, the switch tube Q6, the switch tube Q12 and the switch tube Q9 are all PMOS tubes, the models of the switch tube Q5 and the switch tube Q6 can be AO4409-MS, the models of the switch tube Q12 and the switch tube Q9 can be SI2343DS, the model of the voltage regulator diode D5 can be SB1045, the resistance values ​​of the resistor R15 and the resistor R18 can both be 10K ohms, the resistance values ​​of the resistor R13 and the resistor R10 can both be 100K ohms, and the resistance value of the resistor R16 can be 1K ohm.

[0049] In one embodiment, the power switching circuit 102 also includes a control circuit and a host computer. The control circuit connects the power supply circuit 204 and the host computer. The host computer outputs different levels to control the working state of the control circuit. The working state of the control circuit is used to control the on and off of the power supply circuit 204.

[0050] The host computer can be a computer or a single-chip microcomputer, and it only needs to be able to receive and send level signals. Specifically, the host computer can control the power supply circuit 204 through the control circuit. The host computer changes the working state of the control circuit by outputting different levels, and the working state of the control circuit can affect the working state of the power supply circuit 204, which is specifically manifested in affecting the on-off of the power supply circuit 204.

[0051] Exemplarily, the host computer is a single-chip microcomputer, the control circuit is a switch tube, and the power supply circuit 204 includes a switch. When the single-chip microcomputer controls different states of the switch tube through different levels, the switch in the power supply circuit 204 is correspondingly controlled to be in an open or closed state, thereby realizing the on and off control of the power supply circuit 204.

[0052] In order to facilitate the operation and use of the staff, in one embodiment, the power switching circuit 102 also includes a startup circuit, which is connected to the host computer and each power supply. The startup circuit is used by the staff to control whether to supply power to the load. For example, the startup circuit includes a button, and when the button is pressed, it indicates that the load needs to be powered. Furthermore, the startup circuit can also be connected to the control circuit to achieve dual control of the startup circuit and the host computer over the control circuit, thereby improving the reliability of the power switching circuit 102.

[0053] As shown in FIG6 , the startup circuit includes a button S1, one end of which is connected to each power supply, such as VCC1, VCC2 and VCC3, and the other end of the button S1 is connected to the control end of the switch tube Q1 through a filter voltage stabilization circuit composed of a capacitor C1 and a resistor R6 to control whether the switch tube Q1 is turned on. The input end of the switch tube Q1 is connected to the KEY_SW pin of the host computer, and a 3.3V trigger voltage is connected through the resistor R1, and the output end of the switch tube Q1 is grounded. When the button S1 is closed, the voltage of the power supply is transmitted to the control end of the switch tube Q1, and the switch tube Q1 is turned on. When the switch tube Q1 is turned on, the trigger voltage is grounded through the switch tube Q1, and the KEY_SW pin of the host computer receives a low level. When the switch tube Q1 is turned off, the trigger voltage is transmitted to the KEY_SW pin of the host computer through the resistor R1, and the KEY_SW pin of the host computer is at a high level. At the same time, the end of the button S1 away from the power supply can also be connected to the control circuit (connected through SW-) so that the control circuit can obtain whether the button S1 is closed.

[0054] Among them, a current limiting resistor R4 is set between each power supply and the button S1, a voltage zener diode D1 is set between VCC1 and the current limiting resistor R4, a voltage zener diode D3 is set between VCC2 and the current limiting resistor R4, and a voltage zener diode D4 is set between VCC3 and the current limiting resistor R4. The models of the voltage zener diode D1, the voltage zener diode D3 and the voltage zener diode D4 are all 1N4148, and the resistance of the current limiting resistor R4 is 200K ohms. One end of the capacitor C1 and the resistor R6 after being connected in parallel is connected to the common end of the button S1 and the switch tube Q1, and the other end after being connected in parallel is grounded. The capacitance of the capacitor C1 is 100nF, the resistance of the resistor R6 is 100K ohms, the resistance of the resistor R1 is 10K ohms, the model of the switch tube Q1 can be Si2318DS, and the model of the button S1 is SW-PB.

[0055] The upper computer controls the power supply circuit 204 through the control circuit in not only one way. In one embodiment, the power supply circuit 204 includes a master control switch tube, the control end of the master control switch tube is connected to the control circuit, the input end of the master control switch tube is connected to the comparison circuit 202, and the output end of the master control switch tube is connected to the load.

[0056] Specifically, the host computer sends different levels to the control circuit, correspondingly changing the working state of the control circuit, and the working state of the control circuit is reflected to the control end of the master control switch tube, thereby controlling the master control switch tube. Exemplarily, when the working state of the control circuit is a high level and the master control switch tube is an NMOS tube, the power supply circuit 204 is turned on. When the working state of the control circuit is a low level and the master control switch tube is a PMOS tube, the power supply circuit 204 is turned on. Further, in order to reduce power consumption, the control circuit can also be connected to the common end of the power supply circuit 204 and the comparison circuit 202 to obtain the power supply power supply energy, so as to control the power supply switch tube.

[0057] Exemplarily, in one embodiment, as shown in FIG7 , the power switching circuit 102 includes a power supply circuit 204, a comparison circuit 202, a control circuit, a startup circuit, and a host computer. The power supply circuit 204 includes a master control switch tube, which is a switch tube Q8. The control end of the switch tube Q8 is connected to the control circuit, the input end of the switch tube Q8 is connected to the comparison circuit 202, and the output end of the switch tube Q8 is connected to the load (POWER). The comparison circuit 202 includes a power supply guarantee circuit 304 and a power supply selection circuit 302. The power supply guarantee circuit 304, as shown in FIG7 , includes a voltage regulator diode D2, which connects the main power supply (VCC1) and the power supply circuit 204. The power supply selection circuit 302 is shown in FIG4 and FIG5 , and is connected to the common end of the power supply guarantee circuit 304 and the power supply circuit 204 through the POWER_BUS endpoint. The power supply selection circuit 302 has been described in detail above and will not be repeated here.

[0058] The control circuit includes a signal control circuit and a key control circuit. The signal control circuit includes a switch tube Q10. The control end of the switch tube Q10 is connected to the Hold_Main pin of the host computer. The output end of the switch tube Q10 is grounded. The input end of the switch tube Q10 is connected to the control end of the switch tube Q8, and is connected to the common end of the comparison circuit 202 and the power supply circuit 204 through the resistor R10. The key control circuit includes a switch tube Q11 and a voltage stabilizing filter circuit. The voltage stabilizing filter circuit includes a capacitor C4 and a resistor R17 connected in parallel. One end of the parallel connection is connected to the start-up circuit (SW-), and the other end of the parallel connection is grounded. The control end of the switch tube Q11 is connected to the start-up circuit (SW-), the input end of the switch tube Q11 is connected to the control end of the switch tube Q8 and the input end of the switch tube Q10, and the output end of the switch tube Q10 is grounded.

[0059] Optionally, the switch tube Q8 is a PMOS tube, and the model may be AO4409-MS, the switch tube Q10 and the switch tube Q11 are both NMOS tubes, and the model may be Si2318DS, the model of the Zener diode D2 may be SB1045, the resistance values ​​of the resistor R11 and the resistor R17 may both be 100K ohms, and the capacitance value of the capacitor C4 may be 100nF.

[0060] In this embodiment, the host computer controls whether the switch tube Q10 is turned on through the Hold_Main pin, and the startup circuit controls whether the switch tube Q11 is turned on. When either the switch tube Q10 or the switch tube Q11 is turned on, the switch tube Q8 is turned on, the power supply circuit 204 is turned on, and the comparison circuit 202 can supply power to the load, thereby achieving stable and reliable power switching.

[0061] Based on the same technical concept, the embodiment of the present application further provides a power supply system, as shown in Figure 1, the power supply system includes a power supply and a power supply switching circuit 102 as described in the above embodiments. The number of the power supplies is more than two.

[0062] In order to better understand the above solution, in combination with the application scenario shown in FIG1 , a detailed explanation is given below in combination with a specific embodiment.

[0063] In one embodiment, as shown in FIG1 , the power supply system includes a power supply and a power switching circuit. The power switching circuit is shown in FIG7 , including a power supply circuit, a comparison circuit, a control circuit, a startup circuit and a host computer, and the host computer is a single-chip microcomputer. The specific circuit diagrams are shown in FIG4-FIG7 , which have been described in detail above and will not be repeated here. Among them, the power supply priority and voltage of VCC1 are higher than those of VCC2 and VCC3. The voltages of VCC2 and VCC3 are not limited, but the power supply priority of VCC3 is higher than that of VCC2.

[0064] When there is only VCC1, VCC1 becomes the output power of the POWER_BUS endpoint through the voltage regulator diode D2. When the button S1 is pressed, the switch tube Q11 is turned on, and the control switch tube Q8 is turned on, and the power supply system is running. The microcontroller detects that the button S1 is pressed (the switch tube Q1 is turned on instantaneously, and the microcontroller receives a low level), and controls the Hold_Main pin to turn on the switch tube Q10 to maintain the power supply state of the power supply system.

[0065] When there is only VCC2, VCC3 has no voltage, and switch tube Q12 is turned on, the voltage pulled up by VCC2 on switch tube Q9 is grounded through switch tube Q12. When switch tube Q9 is turned on, switch tubes Q5 and Q6 are turned on. VCC2 becomes the output power supply of the POWER_BUS endpoint through the voltage regulator diode D5. When button S1 is pressed, switch tubes Q11 and Q8 are turned on, and the power supply system runs. The microcontroller detects that button S1 is pressed, and controls the Hold_Main pin to turn on switch tube Q10 to keep the power supply state.

[0066] When only VCC3 is present, switch Q7 is turned on and becomes the output power supply of the POWER_BUS endpoint through the voltage regulator diode D6. When the key S1 is pressed, switch Q11 and switch Q8 are turned on, and the power supply system operates. The microcontroller detects that the key S1 is pressed, and turns on the switch Q10 by controlling the Hold_Main pin to maintain the power supply state.

[0067] When VCC1 and VCC2 exist at the same time, the voltage of VCC1 is greater than that of VCC2, the voltage regulator diode D2 is turned on, the voltage regulator diode D5 is turned off, and VCC1 becomes the output power supply of the POWER_BUS endpoint. When the button S1 is pressed, the switch tube Q11 and the switch tube Q8 are turned on, and the power supply system operates. The microcontroller detects that the button S1 is pressed, and controls the Hold_Main pin to turn on the switch tube Q10 to maintain the power supply state.

[0068] When VCC1 and VCC3 are present at the same time, switch Q7 is turned off, and VCC1 becomes the output power supply of the POWER_BUS endpoint through the voltage regulator diode D2. When the key S1 is pressed, the switch Q11 and switch Q8 are turned on, and the power supply system operates. The microcontroller detects that the key S1 is pressed, and controls the Hold_Main pin to turn on the switch Q10 to maintain the power supply state.

[0069] When VCC2 and VCC3 exist at the same time, switch tubes Q12, Q5, Q6 and Q9 are turned off, switch tube Q7 is turned on, and VCC3 becomes the output power supply of the POWER_BUS endpoint through the voltage regulator diode D6. When the button S1 is pressed, the switch tubes Q11 and Q8 are turned on, and the power supply system operates. The microcontroller detects that the button S1 is pressed, and controls the Hold_Main pin to turn on the switch tube Q10 to maintain the power supply state.

[0070] When VCC1, VCC2 and VCC3 are present at the same time, switch tubes Q7, Q5, Q6, Q9 and Q12 are turned off, and VCC1 becomes the output power supply of the POWER_BUS endpoint through the voltage regulator diode D2. When the button S1 is pressed, the switch tubes Q11 and Q8 are turned on, and the power supply system operates. The microcontroller detects that the button S1 is pressed, and controls the Hold_Main pin to turn on the switch tube Q10 to maintain the power supply state.

[0071] In this embodiment, switching among three power supplies is achieved through a power switching circuit, thereby avoiding power supply competition among power supplies, avoiding the problem of power failure during switching, and improving stability during the power switching process.

[0072] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A power switching circuit, characterized in that: The power switching circuit includes a power supply circuit and a comparison circuit. The power supply circuit is connected to the comparison circuit and the load. The input end of the comparison circuit is connected to different power supplies. The comparison circuit compares the voltages of the power supplies to determine the power supply. The power supply is transmitted to the load through the power supply circuit.

2. The power switching circuit according to claim 1, characterized in that: The comparison circuit includes a power supply guarantee circuit and a power supply selection circuit, the power supply guarantee circuit and the power supply selection circuit are connected to the power supply circuit, the power supply guarantee circuit is connected to the main power supply, and the power supply selection circuit is connected to the main power supply and the secondary power supply; the power supply selection circuit is used to compare the voltages of each connected power supply; the output power supply of the power supply selection circuit is compared with the output power supply of the power supply guarantee circuit to determine the power supply.

3. The power switching circuit according to claim 2, characterized in that: The power supply selection circuit includes a comparison switch tube, a control end of the comparison switch tube is connected to the main power supply, an input end of the comparison switch tube is connected to the secondary power supply, and an output end of the comparison switch tube is connected to a common end of the power supply circuit and the power supply guarantee circuit.

4. The power switching circuit according to claim 3, characterized in that: The power supply selection circuit also includes a voltage regulator tube, which is arranged between the output end of the comparison switch tube and the power supply circuit.

5. The power switching circuit according to claim 3, characterized in that: The power supply selection circuit also includes a voltage judgment circuit, the input end of the voltage judgment circuit is connected to the main power supply and the secondary power supply, and the output end of the voltage judgment circuit is connected to the control end of the comparison switch tube.

6. The power switching circuit according to claim 5, characterized in that: The voltage judgment circuit includes a voltage detection switch tube and a judgment switch tube. The control end of the voltage detection switch tube is connected to the main power supply, the output end of the voltage detection switch tube is connected to the control end of the judgment switch tube, the input end of the voltage detection switch tube is grounded, the control end of the judgment switch tube is connected to the secondary power supply, the output end of the judgment switch tube is connected to the control end of the comparison switch tube, and the input end of the judgment switch tube is grounded.

7. The power switching circuit according to claim 1, characterized in that: The power switching circuit also includes a control circuit and a host computer. The control circuit is connected to the power supply circuit and the host computer. The host computer outputs different levels for controlling the working state of the control circuit. The working state of the control circuit is used to control the on and off of the power supply circuit.

8. The power switching circuit according to claim 7, characterized in that: The power supply circuit includes a master control switch tube, a control end of the master control switch tube is connected to the control circuit, an input end of the master control switch tube is connected to the comparison circuit, and an output end of the master control switch tube is connected to the load.

9. The power switching circuit according to claim 7, characterized in that: The power switching circuit also includes a startup circuit, which is connected to the host computer and each of the power supplies.

10. A power supply system, characterized in that: The power supply system includes a power supply and a power switching circuit as described in any one of claims 1 to 9, and the number of the power supplies is more than two.

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