Power supply self-adaptive switching device and sphygmomanometer

Abstract

The embodiment of the invention discloses a power supply self-adaptive switching device and a sphygmomanometer, and relates to the technical field of sphygmomanometer safety protection, the power supply self-adaptive switching device comprises a battery, a power interface, a first switch unit, a second switch unit and a control unit; the first switch unit is connected with the power interface and the control unit; the second switch unit is connected with the battery, the power interface and the control unit; if power input exists in the power interface, the first switch unit is switched on, the second switch unit is switched off, and the power input by the power interface supplies power to the control unit; if the power interface does not have power input, the first switch unit is switched off, the second switch unit is switched on, and the battery supplies power to the control unit, so that when the external power supply is suddenly powered off, the battery is automatically switched to supply power to the control unit, and the control unit can still control the cuff; and the situation that a user is injured due to the fact that the cuff cannot be loosened due to power failure is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of safety protection of sphygmomanometers, and in particular to a power supply adaptive switching device and a sphygmomanometer. Background Art

[0002] The electronic sphygmomanometer can realize automatic detection of blood pressure and automatic winding of the cuff. A considerable number of electronic sphygmomanometers in the prior art use the oscillometric method to measure blood pressure. During the measurement process, the cuff is automatically wrapped around the arm, then the airbag is inflated to block the blood flow in the artery, and then gradually leaks air. Then, during the deflation process, the gas pressure in the cuff is detected and the weak pulse wave is extracted. As a Class II medical device, the electronic sphygmomanometer has extremely high safety requirements.

[0003] The electronic blood pressure monitor needs to be connected to a 220V grid power supply to work. In actual use, the blood pressure monitor may suddenly lose power due to power outages, accidental touches, etc. Assuming that the blood pressure monitor cuff has been wrapped around the arm and the air bag has been inflated to block the flow of blood vessels, if the power is suddenly cut off at this time, the cuff cannot be loosened and the air bag cannot be deflated, which will squeeze the arm for a long time and cause damage to the human body. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is that when the external power supply of the sphygmomanometer is cut off, the cuff cannot be loosened, which may cause harm to the user.

[0005] In order to solve the above problems, in a first aspect, an embodiment of the present invention provides a power supply adaptive switching device, wherein the power supply adaptive switching device includes a battery, a power interface, a first switch unit, a second switch unit and a control unit;

[0006] The first switch unit is connected to the power interface and the control unit; the second switch unit is connected to the battery, the power interface and the control unit;

[0007] Wherein, if there is power input to the power interface, the first switch unit is turned on and the second switch unit is turned off, so that the power input from the power interface supplies power to the control unit;

[0008] If there is no power input to the power interface, the first switch unit is turned off and the second switch unit is turned on, so that the battery supplies power to the control unit.

[0009] Its further technical solution is that the first switch unit includes an NPN transistor and a first PMOS tube; the base of the NPN transistor is connected to the power interface, the collector of the NPN transistor is connected to the gate of the first PMOS tube, and the emitter of the NPN transistor is grounded; the drain of the first PMOS tube is connected to the power interface, and the source of the first PMOS tube is connected to the control unit.

[0010] Its further technical solution is that the second switch unit includes a second PMOS tube and a third PMOS tube; the source of the second PMOS tube is connected to the battery, the gate of the second PMOS tube is connected to the power interface, the drain of the second PMOS tube is connected to the gate of the first PMOS tube and the drain of the third PMOS tube; the gate of the third PMOS tube is connected to the power interface, and the source of the third PMOS tube is connected to the control unit.

[0011] Its further technical solution is that the second switching unit also includes a first resistor and a second resistor; one end of the first resistor is connected to the gate of the second PMOS tube, the gate of the third PMOS tube and the power interface, the other end of the first resistor is connected to the base of the transistor and the second resistor, and the second resistor is grounded.

[0012] A further technical solution is that the power supply adaptive switching device also includes a step-down unit, and the power interface is connected to the first switch unit via the step-down unit.

[0013] Its further technical solution is that the step-down unit includes an inductor, a first capacitor, a second capacitor, a DC-DC converter, a third capacitor and a fourth capacitor; the inductor is connected to the power interface and the input end of the DC-DC converter, and the output end of the DC-DC converter is connected to the first switch unit; the first capacitor and the second capacitor are connected to the input end of the DC-DC converter and are grounded; the third capacitor and the fourth capacitor are connected to the output end of the DC-DC converter and are grounded.

[0014] Its further technical solution is that the step-down unit also includes a unidirectional TVS tube and a first bidirectional TVS tube; the cathode of the unidirectional TVS tube is connected to the power interface, and the anode of the unidirectional TVS tube is grounded; the first bidirectional TVS tube is connected to the output end of the DC-DC converter and is grounded.

[0015] A further technical solution is that the power supply adaptive switching device also includes a diode, the positive electrode of the diode is connected to the power interface, and the negative electrode of the diode is connected to the first switch unit, the second switch unit and the step-down unit.

[0016] Its further technical solution is that the power supply adaptive switching device also includes an emergency switch unit, the emergency switch unit includes an emergency button and a fourth PMOS tube, the source of the fourth PMOS tube is connected to the first switch unit and the second switch unit, the drain of the fourth PMOS tube is connected to the control unit, and the gate of the fourth PMOS tube is grounded; the emergency button is connected to the source of the fourth PMOS tube and the gate of the fourth PMOS tube.

[0017] In a second aspect, an embodiment of the present invention provides a sphygmomanometer, which includes the power supply adaptive switching device as described in the first aspect.

[0018] Compared with the prior art, the technical effects achieved by the embodiments of the present invention include:

[0019] In the technical solution of the embodiment of the present invention, the power supply adaptive switching device includes a battery, a power interface, a first switch unit, a second switch unit and a control unit; the first switch unit is connected to the power interface and the control unit; the second switch unit is connected to the battery, the power interface and the control unit; if there is power input to the power interface, the first switch unit is turned on and the second switch unit is turned off, so that the control unit is powered by the power input from the power interface; if there is no power input to the power interface, the first switch unit is turned off and the second switch unit is turned on, so that the control unit is powered by the battery, so that when the external power supply is suddenly cut off, it can automatically switch to the battery to power the control unit, so that the control unit can still control the cuff, avoiding the situation where the cuff cannot be loosened due to power outage and causes harm to the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0023] Figure 1 A circuit block diagram of a power supply adaptive switching device proposed in an embodiment of the present invention;

[0024] Figure 2 Another circuit block diagram of a power supply adaptive switching device proposed in an embodiment of the present invention;

[0025] Figure 3 A circuit diagram of a power supply adaptive switching device proposed in an embodiment of the present invention.

[0026] Reference numerals

[0027] Battery 10, power interface 20, first switch unit 30, second switch unit 40, control unit 50, step-down unit 60, emergency switch unit 70, NPN transistor Q27, first PMOS tube Q26, second PMOS tube Q16, third PMOS tube Q25, first resistor R66, second resistor R35, inductor L8, first capacitor C14, second capacitor EC1, DC-DC converter U6, third capacitor C16, fourth capacitor EC2, unidirectional TVS tube TVS2, first bidirectional TVS tube ESD15, diode D11, emergency button J20, fourth PMOS tube Q5, second bidirectional TVS tube ESD16, third bidirectional TVS tube ESD17. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Similar component numbers in the drawings represent similar components. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0030] It should also be understood that the terms used in this description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms.

[0031] See also Figure 1-Figure 3 The embodiment of the present invention proposes a power supply adaptive switching device, which can automatically switch to the battery 10 for power supply when the external power supply is powered off, thereby ensuring that the control unit 50 of the sphygmomanometer is not powered off, so that the control unit 50 can also control the cuff to loosen after the external power supply is powered off, ensuring safety. In order to achieve the above technical purpose, the power supply adaptive switching device includes a battery 10, a power interface 20, a first switch unit 30, a second switch unit 40 and a control unit 50, and the specific structure is described as follows:

[0032] When in use, the power interface 20 is connected to the adapter for external power input, and the power input at the power interface 20 is VCC_6V. The control unit 50 may be specifically an MCU (microcontroller), which is connected to the cuff and can control the cuff.

[0033] The first switch unit 30 is connected to the power interface 20 and the control unit 50 ; the second switch unit 40 is connected to the battery 10 , the power interface 20 and the control unit 50 .

[0034] In an embodiment of the present invention, if there is power input to the power interface 20, the first switch unit 30 is turned on and the second switch unit 40 is turned off, so that the power input from the power interface 20 supplies power to the control unit 50; if there is no power input to the power interface 20, the first switch unit 30 is turned off and the second switch unit 40 is turned on, so that the battery 10 supplies power to the control unit 50.

[0035] Specifically, when there is power input to the power interface 20, that is, when there is external power input, the external power supply can turn on the first switch unit 30 on the one hand, and turn off the second switch unit 40 on the other hand. At this time, the control unit 50 is powered by the external power supply.

[0036] Furthermore, if the external power supply is suddenly cut off, that is, there is no power input to the power interface 20 , then at this time, the first switch unit 30 is disconnected and the second switch unit 40 is turned on, and the battery 10 supplies power to the control unit 50 .

[0037] It can be seen that by applying the technical solution of the embodiment of the present invention, when the external power supply is suddenly cut off, it can automatically switch to the battery 10 to supply power to the control unit 50, and the control unit 50 can still control the cuff. Specifically, if it is detected that the cuff is not in the maximum diameter state at this time, the control unit 50 immediately controls the cuff to loosen (or the motor in the cuff is reversed), so that the blood pressure monitor automatically loosens the cuff when the power is suddenly cut off, ensuring the safety of the tester.

[0038] In the technical solution of the embodiment of the present invention, the power supply adaptive switching device includes a battery 10, a power interface 20, a first switch unit 30, a second switch unit 40 and a control unit 50; the first switch unit 30 is connected to the power interface 20 and the control unit 50; the second switch unit 40 is connected to the battery 10, the power interface 20 and the control unit 50; if there is power input to the power interface 20, the first switch unit 30 is turned on and the second switch unit 40 is turned off, so that the power input from the power interface 20 is used to power the control unit 50; if there is no power input to the power interface 20, the first switch unit 30 is turned off and the second switch unit 40 is turned on, so that the battery 10 is used to power the control unit 50, so that when the external power supply is suddenly cut off, it can automatically switch to the battery 10 to power the control unit 50, so that the control unit 50 can still control the cuff, avoiding the situation that the cuff cannot be loosened due to power failure and causes harm to the user.

[0039] In some embodiments, such as the present embodiment, the first switch unit 30 includes an NPN transistor Q27 and a first PMOS transistor Q26; the base of the NPN transistor Q27 is connected to the power interface 20, the collector of the NPN transistor Q27 is connected to the gate of the first PMOS transistor Q26, and the emitter of the NPN transistor Q27 is grounded; the drain of the first PMOS transistor Q26 is connected to the power interface 20, and the source of the first PMOS transistor Q26 is connected to the control unit 50.

[0040] Specifically, a current limiting resistor R14 may be further provided between the collector of the NPN transistor Q27 and the gate of the first PMOS transistor Q26 , and the current limiting resistor R14 plays a role of current limiting.

[0041] When power is input to the power interface 20 , the NPN transistor Q27 and the first PMOS transistor Q26 are turned on. At this time, the control unit 50 is powered by the external power supply.

[0042] Further, the second switch unit 40 includes a second PMOS tube Q16 and a third PMOS tube Q25; the source of the second PMOS tube Q16 is connected to the battery 10, the gate of the second PMOS tube Q16 is connected to the power interface 20, the drain of the second PMOS tube is connected to the gate of the first PMOS tube Q26 and the drain of the third PMOS tube Q25; the gate of the third PMOS tube Q25 is connected to the power interface 20, and the source of the third PMOS tube Q25 is connected to the control unit 50.

[0043] Specifically, when power is input to the power interface 20 , the second PMOS transistor Q16 and the third PMOS transistor Q25 are turned off, and the NPN transistor Q27 and the first PMOS transistor Q26 are turned on. At this time, the control unit 50 is powered by an external power supply.

[0044] When there is no power input to the power interface 20 , the second PMOS transistor Q16 and the third PMOS transistor Q25 are turned on, and the NPN transistor Q27 and the first PMOS transistor Q26 are turned off. At this time, the battery 10 supplies power to the control unit 50 .

[0045] Furthermore, the second switch unit 40 also includes a first resistor R66 and a second resistor R35; one end of the first resistor R66 is connected to the gate of the second PMOS tube Q16, the gate of the third PMOS tube Q25 and the power interface 20, and the other end of the first resistor R66 is connected to the base of the transistor and the second resistor R35, and the second resistor R35 is grounded.

[0046] Specifically, the first resistor R66 and the second resistor R35 can ensure that when there is no external power input to the power interface 20, the gate of the second PMOS tube Q16 and the gate of the third PMOS tube Q25 can be reliably grounded; at the same time, it can also ensure that when there is external power input to the power interface 20, the power interface 20 and the base of the transistor are prevented from being directly grounded and being pulled down.

[0047] In order to adapt the voltage of the external power supply to the voltage of the power supply unit, in some embodiments, the power supply adaptive switching device further includes a step-down unit 60 , and the power interface 20 is connected to the first switch unit 30 via the step-down unit 60 .

[0048] Specifically, the voltage of the external power source can be converted into a voltage suitable for the control unit 50 by the voltage reduction unit 60, so as to achieve voltage adaptation. For example, the 6V voltage of the external power source is converted into 3.3V to supply power to the control unit 50.

[0049] Further, in some embodiments, the step-down unit 60 is specifically a voltage-stabilizing LDO circuit, which has the functions of voltage conversion and voltage stabilization. Specifically, the step-down unit 60 includes an inductor L8, a first capacitor C14, a second capacitor EC1, a DC-DC converter U6, a third capacitor C16 and a fourth capacitor EC2; the inductor L8 is connected to the power interface 20 and the input end of the DC-DC converter U6, and the output end of the DC-DC converter U6 is connected to the first switch unit 30 (specifically, the output end of the DC-DC converter U6 is connected to the drain of the first PMOS tube Q26); the first capacitor C14 and the second capacitor EC1 are connected to the input end of the DC-DC converter U6 and are grounded; the third capacitor C16 and the fourth capacitor EC2 are connected to the output end of the DC-DC converter U6 and are grounded.

[0050] Specifically, the DC-DC converter U6 further includes a ground terminal, which is grounded. The fourth capacitor EC2 is further connected in parallel with a discharge resistor R67. The DC-DC converter U6 can convert voltage, and the voltage output by the step-down unit 60 can be made more stable through the inductor L8, the first capacitor C14, the second capacitor EC1, the third capacitor C16 and the fourth capacitor EC2, thereby ensuring stable power supply to the control unit 50.

[0051] Furthermore, in some embodiments, the step-down unit 60 also includes a unidirectional TVS tube TVS2 and a first bidirectional TVS tube ESD15; the cathode of the unidirectional TVS tube TVS2 is connected to the power interface 20, and the anode of the unidirectional TVS tube TVS2 is grounded; the first bidirectional TVS tube ESD15 is connected to the output end of the DC-DC converter U6 and is grounded.

[0052] Specifically, the unidirectional TVS tube TVS2 and the first bidirectional TVS tube ESD15 are surge and electrostatic protection devices for improving the safety of the circuit.

[0053] Furthermore, in some embodiments, such as the present embodiment, the power supply adaptive switching device also includes a diode D11, the positive electrode of the diode D11 is connected to the power interface 20, and the negative electrode of the diode D11 is connected to the first switch unit 30, the second switch unit 40 and the step-down unit 60 (specifically, the negative electrode of the diode D11 is connected to the inductor L8, the gate of the second PMOS tube Q16, the gate of the third PMOS tube Q25 and the base of the transistor).

[0054] Specifically, the diode D11 can make the current flow in one direction, thereby preventing the current from flowing back to the power interface 20, thereby improving safety.

[0055] Further, in some embodiments, such as the present embodiment, the power supply adaptive switching device also includes an emergency switch unit 70, the emergency switch unit 70 includes an emergency button J20 and a fourth PMOS tube Q5, the source of the fourth PMOS tube Q5 is connected to the first switch unit 30 and the second switch unit 40 (specifically, the source of the fourth PMOS tube Q5 is connected to the source of the first PMOS tube Q26 and the source of the third PMOS tube Q25), the drain of the fourth PMOS tube Q5 is connected to the control unit 50, the gate of the fourth PMOS tube Q5 is grounded, specifically, the gate of the fourth PMOS tube Q5 can be grounded through a resistor R116; the emergency button J20 is connected to the source of the fourth PMOS tube Q5 and the gate of the fourth PMOS tube Q5.

[0056] Specifically, after pressing the emergency button J20, the voltages of the source and gate of the fourth PMOS tube Q5 are made the same, and the fourth PMOS tube Q5 is disconnected, thereby powering off the fourth PMOS tube Q5 and improving safety.

[0057] Furthermore, the gate of the fourth PMOS transistor Q5 is grounded through the second bidirectional TVS transistor ESD16, and the source of the fourth PMOS transistor Q5 is grounded through the third bidirectional TVS transistor ESD17. The second bidirectional TVS transistor ESD16 and the third bidirectional TVS transistor ESD17 are surge and electrostatic protection devices to improve the safety of the circuit.

[0058] See also Figure 3 The working principle of the power supply adaptive switching device proposed in the embodiment of the present invention is as follows:

[0059] 1. When there is power input to the power interface 20, the voltage is conducted from the diode D11 to the step-down unit 60, and is converted to 3.6V by the step-down unit 60. The voltage input to the power interface 20 turns on the NPN transistor Q27, and the gate of the first PMOS tube Q26 is also connected to the ground and is normally turned on. At the same time, the first PMOS tube Q26 is in a reverse connection state, and the drain to the source is naturally turned on; the gate of the fourth PMOS tube Q5 is grounded through the resistor R116 and is in a conducting state. At this time, the power supply voltage of the control unit 50 is 3.6V. Further, the gate voltage of the third PMOS tube Q25 is greater than the source voltage, and the third PMOS tube Q25 is in a cut-off state from the source to the drain; the gate voltage of the second PMOS tube Q16 is greater than the source voltage, and the second PMOS tube Q16 is in a cut-off state from the source to the drain, thereby cutting off the power supply of the battery 10.

[0060] It can be seen that when there is power input to the power interface 20 , the input voltage can be stepped down by the step-down unit 60 and then conducted to the control unit 50 , but not to the battery 10 ; meanwhile, the battery 10 cannot be conducted to the control unit 50 either.

[0061] 2. When there is no power input to the power interface 20, the gates of the second PMOS tube Q16 and the third PMOS tube Q25 can be connected to the ground through the first resistor R66 and the second resistor R35, the second PMOS tube Q16 and the third PMOS tube Q25 are in the on state, the gate of the fourth PMOS tube Q5 is grounded through the resistor R116 and is in the on state, and at this time the battery 10 supplies power to the control unit 50; further, because the power interface 20 is a low voltage, the NPN transistor Q27 is in the off state, and at the same time, the gate voltage of the first PMOS tube Q26 is equal to the voltage of the battery 10, and it is in the off state from the source to the drain.

[0062] It can be seen that when there is power input to the power interface 20, the battery 10 can supply power to the control unit 50 without being connected to the voltage output terminal of the voltage stabilizing unit.

[0063] An embodiment of the present invention provides a blood pressure meter, which includes the power supply adaptive switching device provided by any of the above embodiments.

[0064] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0065] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0066] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0067] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be connected, detachably connected, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0069] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0070] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0071] The above is a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A power supply adaptive switching device, characterized in that: It includes a battery, a power interface, a first switch unit, a second switch unit and a control unit; The first switch unit is connected to the power interface and the control unit; the second switch unit is connected to the battery, the power interface and the control unit; Wherein, if there is power input to the power interface, the first switch unit is turned on and the second switch unit is turned off, so that the power input from the power interface supplies power to the control unit; If there is no power input to the power interface, the first switch unit is turned off and the second switch unit is turned on, so that the battery supplies power to the control unit.

2. The power supply adaptive switching device according to claim 1, characterized in that: The first switch unit includes an NPN transistor and a first PMOS transistor; the base of the NPN transistor is connected to the power interface, the collector of the NPN transistor is connected to the gate of the first PMOS transistor, and the emitter of the NPN transistor is grounded; the drain of the first PMOS transistor is connected to the power interface, and the source of the first PMOS transistor is connected to the control unit.

3. The power supply adaptive switching device according to claim 2, characterized in that: The second switch unit includes a second PMOS tube and a third PMOS tube; the source of the second PMOS tube is connected to the battery, the gate of the second PMOS tube is connected to the power interface, the drain of the second PMOS tube is connected to the gate of the first PMOS tube and the drain of the third PMOS tube; the gate of the third PMOS tube is connected to the power interface, and the source of the third PMOS tube is connected to the control unit.

4. The power supply adaptive switching device according to claim 3, characterized in that: The second switch unit also includes a first resistor and a second resistor; one end of the first resistor is connected to the gate of the second PMOS tube, the gate of the third PMOS tube and the power interface, the other end of the first resistor is connected to the base of the transistor and the second resistor, and the second resistor is grounded.

5. The power supply adaptive switching device according to claim 1, characterized in that: The power supply adaptive switching device further includes a step-down unit, and the power interface is connected to the first switch unit via the step-down unit.

6. The power supply adaptive switching device according to claim 5, characterized in that: The step-down unit includes an inductor, a first capacitor, a second capacitor, a DC-DC converter, a third capacitor and a fourth capacitor; the inductor is connected to the power interface and the input end of the DC-DC converter, and the output end of the DC-DC converter is connected to the first switch unit; the first capacitor and the second capacitor are connected to the input end of the DC-DC converter and are grounded; the third capacitor and the fourth capacitor are connected to the output end of the DC-DC converter and are grounded.

7. The power supply adaptive switching device according to claim 6, characterized in that: The step-down unit also includes a unidirectional TVS tube and a first bidirectional TVS tube; the cathode of the unidirectional TVS tube is connected to the power interface, and the anode of the unidirectional TVS tube is grounded; the first bidirectional TVS tube is connected to the output end of the DC-DC converter and is grounded.

8. The power supply adaptive switching device according to claim 5, characterized in that: The power supply adaptive switching device also includes a diode, the anode of the diode is connected to the power interface, and the cathode of the diode is connected to the first switch unit, the second switch unit and the step-down unit.

9. The power supply adaptive switching device according to claim 1, characterized in that: The power supply adaptive switching device also includes an emergency switch unit, which includes an emergency button and a fourth PMOS tube, the source of the fourth PMOS tube is connected to the first switch unit and the second switch unit, the drain of the fourth PMOS tube is connected to the control unit, and the gate of the fourth PMOS tube is grounded; the emergency button is connected to the source of the fourth PMOS tube and the gate of the fourth PMOS tube.

10. A sphygmomanometer, characterized in that: The sphygmomanometer comprises the power supply adaptive switching device as described in any one of claims 1-9.

Images