A power switching circuit

Abstract

The application discloses a power switching circuit. The circuit comprises a first power supply and a second power supply, which respectively generate a first voltage and a second voltage to supply power for a load; a first switch unit, whose first end and second end are connected with the first power supply and the load respectively; a second switch unit, whose first end and second end are connected with the second power supply and the load respectively; a first comparison unit, which has a preset first hysteresis voltage, a first input end connected with the second end of the first switch unit, a second input end connected with the first power supply, and an output end connected with the control end of the first switch unit; and a second comparison unit, which has a preset second hysteresis voltage, a first input end connected with the first power supply, a second input end connected with a preset reference voltage source, and an output end connected with the control end of the second switch unit and the second input end of the first comparison unit. The application can solve the problems of false triggering and unstable switching caused by voltage fluctuation or noise interference in the power switching process.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, specifically to a power switching circuit. Background Technology

[0002] Modern electronic devices and systems place high demands on the stability and reliability of their power supply architecture. To prevent system downtime caused by a single power supply failure, a common practice is to employ a multi-power supply architecture, using switching circuits to switch between the main power supply and backup power supplies to ensure continuous power supply to the load. Currently, common implementation methods include using diode characteristics for multi-power supply redundancy protection and using dedicated power control chips (such as ideal diode controllers) for multi-power supply redundancy protection.

[0003] However, existing technologies still have significant limitations: diodes have large forward voltage drops and more significant energy losses, making them difficult to meet the needs of applications sensitive to power supply efficiency; while dedicated power control chips, although feature-rich, are expensive, hindering large-scale adoption. Therefore, how to improve the stability of the switching process while reducing losses and taking cost factors into account remains a pressing technical problem to be solved. Utility Model Content

[0004] In view of the above problems, this application provides a power switching circuit to solve the above technical problems.

[0005] This application provides a power switching circuit, including:

[0006] A first power supply and a second power supply, wherein the first power supply is used to generate a first voltage to power the load, and the second power supply is used to generate a second voltage to power the load.

[0007] The first switching unit has its first terminal and second terminal connected to the first power supply and the load, respectively, so that the first power supply can supply power to the load when it is turned on.

[0008] The second switching unit has its first and second terminals connected to the second power supply and the load, respectively, so that the second power supply can supply power to the load when it is turned on.

[0009] The first comparison unit has a preset first hysteresis voltage, a first input terminal connected to the second terminal of the first switching unit, a second input terminal connected to the first power supply, and an output terminal connected to the control terminal of the first switching unit to control the on / off state of the first switching unit.

[0010] The second comparison unit has a preset second hysteresis voltage, a first input terminal connected to a first power supply, a second input terminal connected to a preset reference voltage source to receive a reference voltage, an output terminal connected to the control terminal of the second switching unit to control the on / off state of the second switching unit, and a second input terminal connected to the first comparison unit to control the output result of the first comparison unit.

[0011] Specifically, when the first voltage is higher than the reference voltage, the first switching unit is turned on and the second switching unit is turned off; when the first voltage is lower than the reference voltage, the second switching unit is turned on and the first switching unit is turned off.

[0012] The power switching circuit provided in this application, through the coordinated operation of the first comparison unit and the first switching unit, and the second comparison unit and the second switching unit, and by introducing a hysteresis characteristic in the comparison unit, enables the first power supply to be powered when the first power supply voltage is higher than the reference voltage, and the second power supply to be powered when the first power supply voltage is lower than the reference voltage. This solves the problems of false triggering and unstable switching caused by voltage fluctuations or noise interference during power switching. The power switching circuit provided in this application can quickly switch to the second power supply when the first power supply fails, and switch back in time when the first power supply is restored, thereby ensuring continuous power supply to the load. It has the technical effects of reliable switching process, strong anti-interference ability and high load power supply continuity.

[0013] These or other aspects of this application will become more apparent in the following description of the embodiments. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A schematic diagram of a power switching circuit provided in an embodiment of this application is shown.

[0016] Figure 2 Another schematic diagram of the power switching circuit provided in an embodiment of this application is shown.

[0017] Figure 3 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application.

[0018] Figure 4 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application.

[0019] Figure 5 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application.

[0020] Figure 6 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application.

[0021] Figure 7This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application.

[0022] Figure 8 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application.

[0023] Figure 9 The diagram shows a schematic diagram of the power switching circuit provided in an embodiment of this application.

[0024] Figure 10 The diagram shows another structural schematic of the power switching circuit provided in the embodiment of this application.

[0025] Figure 11 A schematic diagram of a power switching circuit according to an embodiment of this application is shown.

[0026] Figure 12 The diagram shows the output voltages of the first and second hysteresis comparators at the moment of power-on.

[0027] Figure 13 The diagram shows the output voltages of the first and second hysteresis comparators at the instant of power failure.

[0028] Figure 14 The diagram shows the output voltages of the first and second hysteresis comparators at the instant the first power supply is restored. Detailed Implementation

[0029] To enable those skilled in the art to better understand the solutions of this application, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] In the embodiments of this application, it should be noted that, in this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0031] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0032] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0033] In the embodiments of this application, the first terminal of each transistor is one of the source and the drain, and the second terminal of each transistor is the other of the source and the drain. Since the source and drain of a transistor can be symmetrical in structure, they can be indistinguishable in structure. That is to say, the first terminal and the second terminal of the transistor in the embodiments of this application can be indistinguishable in structure.

[0034] This application provides a power switching circuit. Figure 1 A schematic diagram of the power switching circuit provided in an embodiment of this application is shown, as follows: Figure 1 As shown, the power switching circuit includes a first power supply, a second power supply, a first switching unit, a second switching unit, a first comparison unit, and a second comparison unit.

[0035] A first power supply generates a first voltage to power the load, and a second power supply generates a second voltage to power the load. A first switching unit has its first and second terminals connected to the first power supply and the load, respectively, so that the first power supply powers the load when it is on. A second switching unit has its first and second terminals connected to the second power supply and the load, respectively, so that the second power supply powers the load when it is on. A first comparison unit has a preset first hysteresis voltage. Its first input terminal is connected to the second terminal of the first switching unit, its second input terminal is connected to the first power supply, and its output terminal is connected to the control terminal of the first switching unit to control the on / off state of the first switching unit. A second comparison unit has a preset second hysteresis voltage. Its first input terminal is connected to the first power supply, its second input terminal is connected to a preset reference voltage source to receive the reference voltage, its output terminal is connected to the control terminal of the second switching unit to control the on / off state of the second switching unit, and is also connected to the second input terminal of the first comparison unit to control the output result of the first comparison unit. Specifically, when the first voltage is higher than the reference voltage, the first switching unit is on and the second switching unit is off; when the first voltage is lower than the reference voltage, the second switching unit is on and the first switching unit is off.

[0036] Optionally, when the first voltage output by the first power supply is higher than the reference voltage, the voltage at the first input terminal of the second comparator is greater than its second input terminal voltage, causing the output terminal of the second comparator to output a high level. This high level is input to the control terminal of the second switching unit, causing the second switching unit to turn off. Simultaneously, the first voltage output by the first power supply is input to the second input terminal of the first comparator, and this first voltage is also input to the first input terminal of the first comparator through the first switching unit. Since the first switching unit has a certain on-resistance, the voltage at the first input terminal of the first comparator will be lower than the voltage at the second input terminal. Furthermore, the current flowing through the first switching unit will also result in a voltage drop, further causing the voltage at the first input terminal to be lower than the voltage at the second input terminal. At this time, the output terminal of the first comparator outputs a low level, which is input to the control terminal of the first switching unit, causing the first switching unit to turn on. Therefore, when the first voltage output by the first power supply is higher than the reference voltage, the first switching unit is on, the second switching unit is off, and the load is powered by the first power supply.

[0037] When the first voltage output by the first power supply is lower than the reference voltage (i.e., when the voltage of the first power supply drops due to a fault or power outage), the voltage at the first input terminal of the second comparator unit is lower than the reference voltage at the second input terminal. The output terminal of the second comparator unit outputs a low level, which is input to the control terminal of the second switching unit, causing the second switching unit to conduct, thus supplying power to the load from the second power supply. Simultaneously, the first voltage output by the first power supply is input to the second input terminal of the first comparator unit, and then through the first switching unit to the first input terminal of the first comparator unit. Because the first input terminal of the first comparator unit is connected to the load via the first switching unit, and the load discharge rate is slower than that of the second input terminal directly connected to the first power supply, and the low level output by the second comparator unit also pulls down the first voltage at the second input terminal of the first comparator unit, the voltage at the first input terminal of the first comparator unit will be lower than the voltage at the second input terminal. At this time, the output terminal of the first comparator unit outputs a high level, which is input to the control terminal of the first switching unit, causing the first switching unit to turn off, blocking the first power supply from supplying power to the load. Therefore, when the first voltage output by the first power supply is lower than the reference voltage, the second switching unit conducts, the first switching unit turns off, and the load is supplied by the second power supply, achieving power priority switching.

[0038] When the first power supply is restored and the system needs to switch back to the first power supply from the second power supply, the power switching logic is the same as the switching logic described earlier when the first voltage output by the first power supply is higher than the reference voltage. That is, the first comparator outputs a low level to turn on the first switch unit; at the same time, the second comparator outputs a high level to turn off the second switch unit, thereby achieving a smooth switchback of the load from the second power supply back to the first power supply. This will not be elaborated further here.

[0039] Optionally, to improve the stability of the power switching circuit, in this embodiment, both the first and second comparison units have preset hysteresis voltages, namely a first hysteresis voltage and a second hysteresis voltage, to form a "judgment threshold range" for the comparison unit through hysteresis characteristics (the difference between the upper threshold and the lower threshold is the hysteresis voltage). When the load current is low, the voltages at the first and second input terminals of the first comparison unit may be very close. Without hysteresis characteristics, the first comparison unit is prone to repeatedly changing its output state due to small voltage fluctuations, causing the first switching unit to switch rapidly between on and off. Similarly, the voltages at the non-inverting and inverting input terminals of the second comparison unit may also be close to the threshold in this case. Without hysteresis characteristics, the second comparison unit may cause the second switching unit to repeatedly turn on or off, affecting the stability of the load power supply. In view of this, this embodiment sets hysteresis voltages for the two comparison units so that the output state is changed only when the difference between the two input voltages of the comparison unit exceeds the hysteresis window, thereby suppressing repeated power switching caused by problems such as switching unit on-resistance, voltage mutation, or differences in device parameters. The hysteresis characteristic of the second comparison unit can also be fed back to the second input terminal of the first comparison unit through its output signal, thereby assisting in calibrating the judgment threshold of the first comparison unit and further ensuring the consistency and stability of the switching logic between the first power supply and the second power supply, so as to fully ensure that the entire power switching process is smooth and without jitter, and meet the load's requirements for power supply continuity.

[0040] It is understood that, in the embodiments of this application, the specific values ​​of the hysteresis voltages of the first comparison unit and the second comparison unit are not limited, and can be set according to the actual circuit design. The first hysteresis voltage and the second hysteresis voltage can be equal or unequal, as long as they can meet the stability and reliability requirements of the power switching circuit under different operating conditions.

[0041] It is understood that, in this embodiment, the core function of the hysteresis voltage for the second comparison unit is to provide an anti-interference buffer for the "comparison judgment between the first voltage and the reference voltage," preventing the switching unit from erroneously switching when the first voltage fluctuates slightly near the reference voltage. Specifically, the judgment logic that the first voltage is higher than the reference voltage needs to be combined with the hysteresis characteristics of the second comparison unit. For example, for the second comparison unit, when the first voltage output by the first power supply is close to the reference voltage, the second comparison unit only outputs a low level to turn on the second switching unit and switch the power supply from the second power supply to the first power supply if the first voltage exceeds the reference voltage plus the second hysteresis voltage; conversely, when the first voltage drops to close to the reference voltage, the second comparison unit only outputs a high level to turn on the second switching unit and switch the load from the first power supply to the second power supply if the first voltage is lower than the reference voltage minus the second hysteresis voltage.

[0042] The power switching circuit provided in this application, through the coordinated operation of the first comparison unit and the first switching unit, and the second comparison unit and the second switching unit, and by introducing hysteresis characteristics in the comparison unit, enables the first power supply to provide power when the first power supply voltage is higher than the reference voltage, and the second power supply to provide power when the first power supply voltage is lower than the reference voltage. This solves the problems of false triggering and unstable switching caused by voltage fluctuations or noise interference during power switching. The power switching circuit provided in this application can quickly switch to the second power supply when the first power supply fails and promptly switch back when the first power supply recovers, thereby ensuring continuous power supply to the load. It has the technical effects of reliable switching process, strong anti-interference capability, and high load power supply continuity. Specifically, compared with the existing technical solution of using diode characteristics to achieve multi-power supply redundancy protection, the power switching circuit provided in this application has lower conduction loss and higher energy efficiency; and compared with the existing technical solution of using a dedicated power control chip (such as an ideal diode controller) to achieve multi-power supply redundancy protection, the power switching circuit provided in this application achieves strong anti-interference capability and stability at a lower cost.

[0043] In some embodiments, Figure 2 Another schematic diagram of the power switching circuit provided in an embodiment of this application is shown, as follows: Figure 2 As shown, in this power switching circuit, the first switching unit includes a first transistor Q1 and a second transistor Q2. The control terminal of the first transistor Q1 is connected to the output terminal of the first comparator unit, its first terminal is connected to the first power supply, and its second terminal is connected to the first input terminal of the first comparator unit and the second transistor Q2, and is also connected to the power supply terminal of the first comparator unit to supply power to the first comparator unit through a body diode. The control terminal of the second transistor Q2 is connected to the output terminal of the first comparator unit, its first terminal is connected to the load, and its second terminal is connected to the first transistor Q1.

[0044] The second switching unit includes a third transistor Q3 and a fourth transistor Q4. The control terminal of the third transistor Q3 is connected to the output terminal of the second comparator unit, its first terminal is connected to the second power supply, its second terminal is connected to the fourth transistor Q4, and it is also connected to the power supply terminal of the second comparator unit to power the second comparator unit through a body diode. The control terminal of the fourth transistor Q4 is connected to the output terminal of the second comparator unit, its first terminal is connected to the load, and its second terminal is connected to the third transistor Q3.

[0045] Optionally, the body diode of the first transistor Q1 is used to provide an operating voltage to the first comparator unit when the first transistor Q1 is not turned on, thereby ensuring that the first comparator unit can operate to output the control signal at the control terminal of the first transistor Q1. Similarly, the body diode of the third transistor Q3 is used to provide an operating voltage to the second comparator unit when the third transistor Q3 is not turned on, thereby ensuring that the second comparator unit can operate to output the control signal at the control terminal of the third transistor Q3.

[0046] Optionally, the first transistor Q1 and the second transistor Q2 are connected in series, and their control terminals are both connected to the output terminal of the first comparator unit to ensure that they are turned on or off synchronously. When the first comparator unit outputs a low level, both the first transistor Q1 and the second transistor Q2 meet the turn-on condition, forming a continuous current path from the first power supply to the load. When the output is high, both are turned off simultaneously. The third transistor Q3 and the fourth transistor Q4 are connected in series, and their connection structure and operating principle are the same as those of the first transistor Q1 and the second transistor Q2.

[0047] The power switching circuit provided in this application embodiment, through the superposition effect of 'dual-transistor cutoff', more reliably blocks the reverse flow of load-side voltage into the first power supply compared to a single-transistor structure. Especially during voltage fluctuations at the moment of power switching, it effectively avoids power conflicts or device damage caused by current backflow, thereby improving the reliability of load power supply.

[0048] In one implementation embodiment of this application, the first transistor Q1, the second transistor Q2, the third transistor Q3, and the fourth transistor Q4 are all P-type MOS transistors. The first terminal of each transistor is the source of the PMOS transistor, the second terminal is the drain of the PMOS transistor, and the control terminal is the gate of the PMOS transistor. At this time, a high level is a high level, and a low level is a low level.

[0049] In some embodiments, Figure 3 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application, such as... Figure 3 As shown, in this power switching circuit, the first comparison unit includes a first hysteresis comparator U1A. The first comparator U1A has a preset first hysteresis voltage. Its non-inverting input terminal is connected to the second terminal of the first switching unit, its inverting input terminal is connected to the first power supply, and its output terminal is connected to the control terminal of the first switching unit to control the on / off state of the first switching unit. That is, the output terminal is connected to the control terminal of the first transistor Q1 and the second transistor Q2.

[0050] The second comparison unit includes a second hysteresis comparator U2A, which has a preset second hysteresis voltage. Its non-inverting input is connected to a first power supply, its inverting input is connected to a preset reference voltage source to receive a reference voltage, and its output is connected to the control terminal of a second switching unit to control the switching on and off. Specifically, the output is connected to the control terminals of the third transistor Q3 and the fourth transistor Q4, and also to the inverting input of the first hysteresis comparator U1A to control its output. Specifically, when the second hysteresis comparator U2A detects that the first voltage is normal, it outputs a high level. This high level is output to the inverting input of the first hysteresis comparator U1A, controlling the voltage at the inverting input to be higher than the voltage at the non-inverting input, thereby maintaining a low output from the first hysteresis comparator U1A to control the first switching unit to conduct. When the second hysteresis comparator U2A detects that the first voltage is lower than the reference voltage, it outputs a low level. This low level is fed back to the inverting input of the first hysteresis comparator U1A, which can also accelerate the voltage drop at the inverting input of the first U1A. This prompts the first hysteresis comparator U1A to quickly output a high level to turn off the first switching unit, thus avoiding path conflict between the first and second power supplies at the moment of switching and realizing the cooperative control closed loop of the two comparators.

[0051] The power switching circuit provided in this application, by selecting a first hysteresis comparator and a second hysteresis comparator with hysteresis characteristics, ensures that the first and second comparison units only switch outputs when the difference between the input voltages at their two input terminals meets the hysteresis characteristic. This effectively avoids repeated switching of the switching unit caused by small fluctuations in input voltage or when the load current is close to zero, thereby improving the stability and reliability of power switching. Simultaneously, the hysteresis design provides a buffer during the recovery or decline of the first power supply, ensuring that the load can smoothly switch to the priority power supply, achieving reliable priority power management.

[0052] In some embodiments, Figure 4 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application, such as... Figure 4 As shown, except through Figure 3 In addition to implementing the first and second hysteresis comparators shown, the power switching circuit also includes a first comparator U1B and a first hysteresis resistor R1. The first comparator unit is implemented using a non-hysteresis comparator and a resistive element. The non-inverting input of the first comparator U1B is connected to the second terminal of the first switching unit, the inverting input is connected to the first power supply, and the output is connected to the control terminal of the first switching unit to control its on / off state. The output is also connected to the inverting input through the first hysteresis resistor R1 to generate a first hysteresis voltage. Specifically, the value of the first hysteresis voltage is determined by the resistance value of the first hysteresis resistor R1, which can be set by the designer according to the actual design requirements.

[0053] The second comparison unit includes a second comparator U2B and a second hysteresis resistor R2. The second comparison unit is implemented using a non-hysteresis comparator and a resistive element. The non-inverting input of the second comparator U2B is connected to the first power supply, and the inverting input is connected to a preset reference voltage source to receive a reference voltage. The output is connected to the control terminal of the second switching unit to control the on / off state of the second switching unit, and is also connected to the inverting input of the first comparator U2B to control the output of the first comparator U1B. Furthermore, the inverting input of the second comparator U2B is connected to the second hysteresis resistor R2 to generate a second hysteresis voltage. Specifically, the value of the second hysteresis voltage is determined by the resistance value of the second hysteresis resistor R2, which can be set by the designer according to the actual design requirements.

[0054] Optionally, in this embodiment of the application, a positive feedback loop is formed by connecting a resistor in series between the inverting input terminal and the output terminal of the non-hysteresis comparator. This allows the comparator to introduce a voltage offset when comparing input signals, thereby generating a controllable hysteresis voltage.

[0055] The power switching circuit provided in this application embodiment implements the design of the first comparison unit and the second comparison unit through a non-hysteresis comparator and a resistor element. It can not only flexibly adjust the hysteresis voltage to adapt to different power supply voltage fluctuations and load changes, but also provide a stable judgment buffer for the comparison unit when the input voltage is close to the reference voltage, avoiding repeated switching of the switching unit due to small fluctuations, thereby improving the reliability of power switching and the overall power supply stability of the system.

[0056] In some embodiments, such as Figures 1 to 4 As shown, in this power switching circuit, the reference voltage source can be configured as a voltage source independent of the first power supply and the second power supply.

[0057] Figure 5 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application, such as... Figure 5 As shown, in this power switching circuit, the reference voltage source can be configured as a voltage source independent of the first power source and the second power source, or it can be configured to be implemented by the second power source and the first voltage divider unit. Specifically, the second power source is connected to the second input terminal of the first voltage divider unit and the second comparison unit. The first voltage divider unit is used to divide the second voltage generated by the second power source according to a preset first voltage division ratio to generate a reference voltage.

[0058] It is understood that the implementation form of the first voltage divider unit is not limited in this application embodiment. It can adopt any applicable form such as a series resistor network or a sliding rheostat, as long as it can divide the input voltage according to the preset first voltage division ratio and meet the circuit's requirements for voltage division accuracy, power consumption and temperature drift characteristics.

[0059] The power switching circuit provided in this application embodiment, through flexible configuration of the reference voltage source, can accurately determine the level of the first power supply's output voltage relative to the reference voltage, whether it is an independent reference voltage source or a reference voltage achieved by voltage division from the second power supply, thereby realizing reliable switching between the first and second switching units. This design not only ensures the stability of power switching but also enhances the circuit's adaptability to different voltage domains and power fluctuations, improving the reliability of load power supply and the overall stability of the system.

[0060] In some embodiments, Figure 6 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application, such as... Figure 6 As shown, the power switching circuit further includes an RC filter unit, which includes a first resistor RL1 and a first capacitor C1. The second input terminal of the first comparator unit is connected to the first power supply through the first resistor RL1, and is connected to the output terminal of the second comparator unit through the first capacitor C1.

[0061] Optionally, the first resistor RL1 and the first capacitor C1 form an RC filter network to smooth the voltage at the second input terminal of the first comparator unit, so that the voltage will not change drastically instantaneously when the first power supply is suddenly cut off or restored, thereby further avoiding repeated switching of the output of the first comparator unit due to small voltage fluctuations.

[0062] In this design, the first capacitor C1, in addition to forming an RC filter network with the first resistor R1L, is also used to precisely control the voltage change at the second input terminal of the first comparator unit when the first power supply is turned off or restored, based on the characteristic that the voltage across the capacitor cannot change abruptly. This ensures that the first comparator unit outputs the correct level. Specifically, when the first power supply is turned off, the first voltage received at the second input terminal of the first comparator unit drops rapidly. Since the first capacitor C1 has been charged by the first voltage, the second comparator unit outputs a low level due to the power outage. Because the voltage across the first capacitor C1 cannot change abruptly, the first capacitor C1 discharges to maintain its voltage, causing the voltage at the second input terminal of the first comparator unit to be pulled down by the low level output by the second comparator unit. This ensures that the voltage at the first input terminal of the first comparator unit is higher than the voltage at the second input terminal, thereby causing the first comparator unit to continuously output a high level to turn off the first switching unit. Similarly, when the first power supply is restored, the voltage at the end of the first capacitor C1 connected to the second input terminal of the first comparator unit quickly recovers to the first voltage. Since the voltage across the first capacitor C1 cannot change abruptly, the end connected to the output terminal of the second comparator unit still retains the residual voltage formed by the discharge during the power outage phase. At this time, the second input terminal of the first comparator unit is simultaneously affected by the first voltage and the residual voltage, causing the voltage at the second input terminal of the first comparator unit to reach the sum of the first voltage and the residual voltage. This causes the voltage at the second input terminal of the first comparator unit to quickly exceed the voltage at the first input terminal, thereby causing the first comparator unit to quickly output a low level to turn on the first switching unit.

[0063] The power switching circuit provided in this application embodiment, by utilizing the voltage gradient characteristics of the RC filter unit, can ensure the timeliness of power switching when the first power is restored and when the power is lost, and can also effectively suppress the erroneous switching of the output of the first comparison unit caused by instantaneous voltage disturbances, fundamentally avoiding frequent switching of the switching unit, and significantly improving the stability and reliability of the circuit in the scenario of dynamic power switching.

[0064] In some embodiments, Figure 7 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application, such as... Figure 7 As shown, the power switching circuit also includes:

[0065] The second voltage divider unit connects the first input terminals of the first power supply and the second comparator unit to divide the first voltage generated by the first power supply according to a preset second voltage division ratio to generate a second voltage divider, which is then output to the first input terminal of the second comparator unit. When the power switching circuit includes the second voltage divider unit, since the second comparator unit receives the second voltage divider and a reference voltage, the power switching logic is as follows: when the second voltage divider is higher than the reference voltage, the first switch unit is turned on and the second switch unit is turned off; when the second voltage divider is lower than the reference voltage, the second switch unit is turned on and the first switch unit is turned off.

[0066] Optionally, the second voltage divider unit is used to adapt to the priority switching logic of the first power supply and the second power supply under different voltage domains, while also meeting the voltage detection requirements of the first input terminal of the second comparator unit. Specifically, when the first voltage and the second power supply voltage are in different voltage domains, there is no need to change the core circuit structure. By simply adjusting the preset voltage division ratio of the second voltage divider unit, the first voltage of the first power supply can be divided into a second voltage that adapts to the first input terminal of the second comparator unit. For example, if the first voltage is greater than the second voltage, the first voltage can be divided by the second voltage divider unit and then connected to the first input terminal of the second comparator unit, so that the second voltage received by the first input terminal of the second comparator unit is less than the reference voltage received by the second input terminal, thereby meeting the operating logic of the power switching circuit provided in this application embodiment.

[0067] It is understood that the implementation form of the first voltage divider unit is not limited in this application embodiment. It can adopt any applicable form such as a series resistor network or a sliding rheostat, as long as it can divide the input voltage according to the preset first voltage division ratio and meet the circuit's requirements for voltage division accuracy, power consumption and temperature drift characteristics.

[0068] It is understood that the implementation form of the second voltage divider unit is not limited in the embodiments of this application. It can be flexibly selected according to the voltage range of the first power supply, the input characteristics of the second comparison unit and the circuit integration requirements. For example, a fixed resistor series structure, an adjustable resistor network or the like can be used, as long as the second voltage divider voltage that meets the detection range of the second comparison unit can be stably output and the linearity and stability of the voltage divider process can be ensured.

[0069] In some embodiments, Figure 8 This illustration shows yet another schematic diagram of the power switching circuit provided in an embodiment of this application, such as... Figure 8 As shown, the power switching circuit also includes a first filter unit and a second filter unit.

[0070] The first filtering unit is connected to the first power supply to filter the first voltage generated by the first power supply. The second filtering unit is connected to the second power supply to filter the second voltage generated by the second power supply.

[0071] It is understood that in the embodiments of this application, there are no restrictions on the implementation of the first filtering unit and the second filtering unit. They can be flexibly selected according to the power supply characteristics and filtering requirements, such as using capacitor filtering, RC filtering, LC filtering, etc., as long as they can effectively suppress the voltage noise of the corresponding power supply and meet the circuit's requirements for power consumption, size and response speed.

[0072] In one embodiment of this application, the first filtering unit and the second filtering unit are implemented using capacitor filtering, and each filtering unit includes at least one capacitor element connected in parallel.

[0073] Figure 9 and Figure 10 Two schematic diagrams of the power switching circuit provided in the embodiments of this application are shown respectively. Figure 9 The power switching circuit shown implements the hysteresis function through a hysteresis comparator. Figure 10 The power switching circuit shown implements hysteresis functionality through a non-hysteresis comparator and a hysteresis resistor, such as... Figure 9 and Figure 10 As shown, the power switching circuit provided in this application embodiment, through the coordinated operation of the first comparator unit with the first transistor Q1 and the second transistor Q2, and the second comparator unit with the third transistor Q3 and the fourth transistor Q4, and by introducing hysteresis characteristics in the first and second comparator units, achieves power supply from the first power supply when the first power supply voltage is higher than the reference voltage, and power supply from the second power supply when the first power supply voltage is lower than the reference voltage. This solves the problems of false triggering and unstable switching caused by voltage fluctuations or noise interference during power switching. The power switching circuit provided in this application can quickly switch to the second power supply when the first power supply fails, and switch back in time when the first power supply is restored, thereby ensuring continuous power supply to the load. It has the technical effects of reliable switching process, strong anti-interference ability, and high load power supply continuity. Specifically, compared with the existing technical solution of using diode characteristics to achieve multi-power supply redundancy protection, the power switching circuit provided in this application embodiment has lower conduction loss and higher energy efficiency; and compared with the existing technical solution of using a dedicated power control chip (such as an ideal diode controller) to achieve multi-power supply redundancy protection, the power switching circuit provided in this application embodiment achieves strong anti-interference ability and stability at a lower cost.

[0074] The following example illustrates the power switching circuit provided in an embodiment of this application. Figure 11 A simulated schematic diagram of the power switching circuit according to an embodiment of this application is shown, such as... Figure 11As shown, a 3.3V power supply V1 represents the first power supply, and switches S1 and S2 simulate the power-on and power-off states of the first power supply. A 5V power supply V2 represents the second power supply, and switch S3 simulates the power-on and power-off states of the second power supply. Because power supply V1 is smaller than power supply V2, therefore... Figure 11 The circuit shown does not require a second voltage divider unit. In practical applications, if V1 is greater than V2, a second voltage divider unit should be set up to divide V1 and connect it to the non-inverting input of comparator U2A.

[0075] Figure 12 The diagram shows the output voltages of the first and second hysteresis comparators at the instant of power-on in the circuit, as follows: Figure 11 and Figure 12 As shown, taking a voltage division ratio of 0.5 for the first voltage divider unit as an example, closing switches S1, S2, and S3 simulates the normal power supply situation of power supply V1. The current from power supply V1 powers the first hysteresis comparator U1A through the body diode of the first transistor Q1, and the current from power supply V2 powers the second hysteresis comparator U2A through the body diode of the third transistor Q3. Since the voltage at the non-inverting input of the second hysteresis comparator U2A (3.3V) is greater than the voltage at the inverting input (2.5V), the output voltage of the second hysteresis comparator U2A is high. The third transistor Q3 and the fourth transistor Q4 are turned off, preventing the current from power supply V2 from flowing to the load. At the same time, due to the voltage drop at the non-inverting input of the first hysteresis comparator caused by the body diode, it will inevitably be less than the voltage at the inverting input (3.3V). Therefore, the output of comparator U1A will output a low level, and the first transistor Q1 and the second transistor Q2 will be turned on. After being turned on, due to the internal resistance of the MOSFET, a voltage drop will occur as current flows through it. This will cause the voltage at the non-inverting input to be lower than the voltage at the inverting input, and the first hysteresis comparator U1A will still output a low level. Tests show that the load operating current is approximately 326mA and the load voltage is approximately 3.26V. When the RDS(on) of the first transistor Q1 and the second transistor Q2 is 60mΩ, the voltage drop generated by the first transistor Q1 and the second transistor Q2 is 326mA * 60mΩ * 2 = 39.12mV.

[0076] Figure 13 The diagram shows the output voltages of the first and second hysteresis comparators at the instant of power failure. Figure 11 and Figure 13As shown, when switch S1 is turned on, simulating a sudden power outage of power supply V1, the second hysteresis comparator U2A first reverses to a low level, turning on the third transistor Q3 and the fourth transistor Q4, allowing power to be supplied to the load from power supply V2. Simultaneously, the first hysteresis comparator U1A reverses to a high level, turning off the first transistor Q1 and the second transistor Q2. Tests show that the load operating current is approximately 495mA and the load voltage is approximately 4.95V. When the RDS(on) of the third transistor Q3 and the fourth transistor Q4 is 60mΩ, the voltage drop generated by the third transistor Q3 and the fourth transistor Q4 is 495mA * 60mΩ * 2 = 59.4mV.

[0077] Figure 14 The diagram shows the output voltages of the first and second hysteresis comparators at the instant the first power supply is restored. Figure 11 and Figure 14 As shown, when switch S1 is closed, the simulated power supply V1 resumes power supply. The output levels of the first hysteresis comparator U1A and the second hysteresis comparator U2A are reversed. The second hysteresis comparator U2A outputs a high level, and the third transistor Q3 and the fourth transistor Q4 are turned off. Simultaneously, the first hysteresis comparator U1A outputs a low level, and the first transistor Q1 and the second transistor Q2 are turned on. The load is then switched to power supply V1 for power. Afterward, the overall circuit operation is consistent with the normal power-on operation described above, which demonstrates that this invention can achieve priority power supply.

[0078] The above description, in conjunction with specific embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications and substitutions should be considered within the scope of protection of this application.

Claims

1. A power switching circuit, characterized in that, include: A first power source and a second power source, wherein the first power source is used to generate a first voltage to supply power to the load, and the second power source is used to generate a second voltage to supply power to the load. A first switching unit has its first terminal and second terminal connected to the first power source and the load, respectively, so that when the switch is turned on, the first power source supplies power to the load. The second switching unit has its first and second terminals connected to the second power supply and the load, respectively, so that the second power supply can supply power to the load when it is turned on. The first comparison unit has a preset first hysteresis voltage, a first input terminal connected to the second terminal of the first switching unit, a second input terminal connected to the first power supply, and an output terminal connected to the control terminal of the first switching unit to control the on / off state of the first switching unit. The second comparison unit has a preset second hysteresis voltage, a first input terminal connected to the first power supply, a second input terminal connected to a preset reference voltage source to receive a reference voltage, an output terminal connected to the control terminal of the second switching unit to control the on / off state of the second switching unit, and a second input terminal connected to the first comparison unit to control the output result of the first comparison unit. Specifically, when the first voltage is higher than the reference voltage, the first switching unit is turned on and the second switching unit is turned off; when the first voltage is lower than the reference voltage, the second switching unit is turned on and the first switching unit is turned off.

2. The power switching circuit as described in claim 1, characterized in that, The first switching unit includes a first transistor and a second transistor. The control terminal of the first transistor is connected to the output terminal of the first comparator unit, the first terminal is connected to the first power supply, the second terminal is connected to the first input terminal of the first comparator unit and the second transistor, and is connected to the power supply terminal of the first comparator unit to supply power to the first comparator unit through the body diode; The control terminal of the second transistor is connected to the output terminal of the first comparator unit, the first terminal is connected to the load, and the second terminal is connected to the first transistor. The second switching unit includes a third transistor and a fourth transistor. The control terminal of the third transistor is connected to the output terminal of the second comparator, the first terminal is connected to the second power supply, the second terminal is connected to the fourth transistor, and the power supply terminal of the second comparator is connected to supply power to the second comparator through the body diode; The control terminal of the fourth transistor is connected to the output terminal of the second comparator unit, the first terminal is connected to the load, and the second terminal is connected to the third transistor.

3. The power switching circuit as described in claim 1, characterized in that, The first comparison unit includes a first hysteresis comparator with a preset first hysteresis voltage. The non-inverting input terminal is connected to the second terminal of the first switching unit, the inverting input terminal is connected to the first power supply, and the output terminal is connected to the control terminal of the first switching unit to control the on / off state of the first switching unit. The second comparison unit includes a second hysteresis comparator with a preset second hysteresis voltage. Its non-inverting input is connected to the first power supply, its inverting input is connected to a preset reference voltage source to receive a reference voltage, its output is connected to the control terminal of the second switching unit to control the on / off state of the second switching unit, and is connected to the inverting input of the first hysteresis comparator to control the output result of the first hysteresis comparator.

4. The power switching circuit as described in claim 1, characterized in that, The first comparison unit includes a first comparator and a first hysteresis resistor. The non-inverting input terminal of the first comparator is connected to the second terminal of the first switching unit, the inverting input terminal is connected to the first power supply, and the output terminal is connected to the control terminal of the first switching unit to control the switching of the first switching unit. The output terminal is connected to the inverting input terminal through the first hysteresis resistor to generate the first hysteresis voltage through the first hysteresis resistor. The second comparison unit includes a second comparator and a second hysteresis resistor. The non-inverting input of the second comparator is connected to the first power supply, the inverting input is connected to a preset reference voltage source to receive a reference voltage, the output is connected to the control terminal of the second switching unit to control the on / off state of the second switching unit, and is connected to the inverting input of the first comparator to control the output result of the first comparator. It is also connected to the inverting input of the second comparator through the second hysteresis resistor to generate the second hysteresis voltage.

5. The power switching circuit as described in claim 1, characterized in that, The reference voltage source is a voltage source independent of the first power supply and the second power supply. Alternatively, the reference voltage source may include a second power supply and a first voltage divider unit. The second power supply is connected to the second input terminal of the second comparison unit through the first voltage divider unit. The first voltage divider unit is used to divide the second voltage generated by the second power supply according to a preset first voltage division ratio to generate the reference voltage.

6. The power switching circuit as described in claim 1, characterized in that, It also includes an RC filter unit, which includes a first resistor and a first capacitor; The second input terminal of the first comparison unit is connected to the first power supply through the first resistor, and is connected to the output terminal of the second comparison unit through the first capacitor.

7. The power switching circuit as described in claim 1, characterized in that, Also includes: The second voltage divider unit connects the first input terminal of the first power supply and the second comparison unit to divide the first voltage generated by the first power supply according to a preset second voltage division ratio to generate a second voltage divider voltage and output it to the first input terminal of the second comparison unit. Specifically, when the second voltage divider is higher than the reference voltage, the first switch unit is turned on and the second switch unit is turned off; when the second voltage divider is lower than the reference voltage, the second switch unit is turned on and the first switch unit is turned off.

8. The power switching circuit as described in claim 1, characterized in that, Also includes: The first filtering unit is connected to the first power supply to filter the first voltage generated by the first power supply. The second filtering unit is connected to the second power supply to filter the second voltage generated by the second power supply.

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