A body diode-based power switching circuit and charger

Abstract

A kind of power supply switching circuit based on body diode and charger, switching circuit includes battery input terminal, external power input terminal, voltage dividing unit connected between the external power input terminal and ground, switch unit the first end of the switch unit is connected the battery input terminal, the second end of the switch unit is output node;Voltage stabilizing module, its input terminal is connected the output node, output terminal is used to output preset voltage, to supply power for load;Wherein, the switch unit is turned on when the external power input terminal is not connected with external power, and is cut off when the external power input terminal is connected with external power.The utility model embodiment is automatically cut off battery power supply path when external power is connected by the passive control of voltage dividing unit and switch unit, need not rely on active device to realize zero static current switching, with the advantages of zero static current, structure simplification, strong low temperature resistance and low cost.

Description

Technical Field

[0001] This utility model relates to the field of charging technology, specifically to a power switching circuit and charger based on a body diode. Background Technology

[0002] Existing technologies typically employ power management chips or ideal diode chips with enable control terminals to achieve power path switching. Level control signals drive switching devices (such as MOSFETs) to turn on or off, thereby determining the current source path. These solutions work in conjunction with an MCU or comparator for logic judgment, controlling power switching based on battery voltage and external power supply status. Some solutions also incorporate Schottky diodes or ideal diode arrays to reduce voltage drop and improve power supply efficiency.

[0003] However, while the aforementioned traditional solutions can achieve power path switching, they generally suffer from the following drawbacks:

[0004] First, the control logic relies on active devices such as MCUs or dedicated comparators, which results in a significant static current in the device even in standby mode, typically above 5μA. For low-capacity power devices such as button batteries and small lithium batteries, this will severely shorten the battery life in the long run.

[0005] Secondly, the external control signal path is complex. If the MCU initialization is abnormal, there is external interference, or the power-on sequence is incorrect, it can easily lead to power supply conflicts, reverse power-on, and other fault risks.

[0006] Therefore, there is an urgent need for a passive power switching circuit solution with a simplified structure, zero power consumption, and strong resistance to low temperatures to replace it. Utility Model Content

[0007] The purpose of this invention is to address the shortcomings and deficiencies of the existing technology by providing a power switching circuit, charger, and power switching method based on a body diode. The power switching circuit has the advantages of zero quiescent current, simplified structure, strong low-temperature resistance, and low cost.

[0008] The technical solution is as follows:

[0009] In a first aspect, this utility model provides a power switching circuit based on a body diode, comprising:

[0010] Battery input terminal, used for electrical connection to the battery;

[0011] External power input terminal, used for electrical connection to an external charging power source;

[0012] A voltage divider unit is connected between the external power input terminal and ground. The voltage divider output terminal of the voltage divider unit is used to divide the voltage of the external power input terminal and output a voltage divider signal.

[0013] A switching unit, wherein the control terminal of the switching unit is connected to the voltage divider output terminal of the voltage divider unit, the first terminal of the switching unit is connected to the battery input terminal, and the second terminal of the switching unit is an output node;

[0014] The voltage regulator module has its input terminal connected to the output node, and its output terminal is used to output a preset voltage to supply power to the load.

[0015] The switching unit is turned on when no external power is connected to the external power input terminal, and turned off when an external power is connected to the external power input terminal.

[0016] Furthermore, the voltage divider unit includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the external power input terminal and the output node, and the other end of the first resistor R1 is connected to one end of the second resistor R2 to form the voltage divider output terminal. The other end of the second resistor R2 is grounded.

[0017] Furthermore, the battery input terminal has an input voltage of 3.7V, and the external power supply input terminal has an input voltage of 5V.

[0018] Furthermore, the switching unit includes a switching transistor Q1, which is a PMOS field-effect transistor. The gate of the switching transistor Q1 is connected to the voltage divider output terminal, the source of the switching transistor Q1 is connected to the output node, and the drain of the switching transistor Q1 is connected to the battery input terminal.

[0019] Furthermore, the resistance ratio of the first resistor R1 to the second resistor R2 is configured such that when the external power supply input voltage is 5V, the voltage at the voltage divider output is controlled to be higher than the source voltage of the switching transistor Q1, thereby turning off the switching transistor Q1.

[0020] Furthermore, a diode D1 is provided between the external power input terminal and the output node. The anode of the diode D1 is connected to the external power input terminal and one end of the first resistor R1, and the cathode of the diode D1 is connected to the output node and the source of the switching transistor Q1.

[0021] Furthermore, the voltage regulator module includes a voltage regulator unit U1, capacitor C1, capacitor C2, and capacitor C3. One end of capacitor C3 is connected to the output node and the input terminal of the voltage regulator unit U1, and the other end of capacitor C3 is connected to the ground terminal of the voltage regulator unit U1. One end of capacitor C2, one end of capacitor C1, and the other end of common ground capacitor C2 and capacitor C1 are connected to the output terminal of the voltage regulator unit U1.

[0022] Furthermore, the resistance ratio of the first resistor R1 to the second resistor R2 is 1:10.

[0023] Secondly, this utility model provides a charger, including the power switching circuit based on a body diode as described above.

[0024] This utility model provides a power switching circuit, charger, and power switching method based on a body diode. Through passive control of the voltage divider unit and the switching unit, the battery power supply path is automatically cut off when an external power source is connected. Zero static current switching can be achieved without relying on active devices. It has the advantages of zero static current, simplified structure, strong low temperature resistance, and low cost. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a circuit structure block diagram of an embodiment of the present utility model;

[0027] Figure 2 This is a schematic diagram of the circuit principle of an embodiment of this utility model;

[0028] Figure 3 This is a circuit diagram of another embodiment of the present invention;

[0029] Figure 4 This is a circuit schematic diagram of another embodiment of the present invention;

[0030] Figure 5 This is a circuit schematic diagram of another embodiment of the present invention.

[0031] Figure label:

[0032] 100. Battery input terminal;

[0033] 200. External power input terminal;

[0034] 300, Voltage Divider Unit;

[0035] 400. Switching unit;

[0036] 500, voltage regulator module. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings.

[0038] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0041] In existing technologies, power switching circuits typically rely on active devices for control, such as power management chips or ideal diode chips used in conjunction with a microcontroller to achieve path switching. These solutions require continuous quiescent current to maintain control logic operation, resulting in high standby power consumption. Furthermore, complex external control signal paths may cause power conflicts due to interference or initialization anomalies, affecting system reliability. In low-temperature or harsh environments, semiconductor device performance degradation may further exacerbate the risk of circuit failure, making it difficult to meet the application requirements of low power consumption and high reliability.

[0042] To address the aforementioned issues, a passive power switching scheme requiring no external control signals and exhibiting zero quiescent current is needed. Traditional schemes rely on active level signals for control of the switching devices, making automatic switching via passive components crucial. Considering that external power supply connections alter circuit node voltages, a voltage divider network is explored to directly control the switching device state. When an external power supply is present, the voltage divider signal should keep the switching device off; when the external power supply is removed, the switching device automatically switches to battery power. This design eliminates dependence on a control chip and avoids quiescent current losses.

[0043] Therefore, refer to Figure 1This application proposes a power switching circuit including a battery input terminal, an external power input terminal, a voltage divider unit, a switching unit, and a voltage regulator module. The voltage divider unit is connected between the external power input terminal and ground, used to divide the external power supply voltage and output a voltage divider signal. The control terminal of the switching unit is connected to the voltage divider output terminal, the first terminal is connected to the battery input terminal, and the second terminal is connected to the output node. The input terminal of the voltage regulator module is connected to the output node, and the output terminal provides a stable voltage to the load. When the external power supply is not connected, the switching unit conducts the battery power supply path; when the external power supply is connected, the switching unit is cut off and powered by the external power supply.

[0044] The voltage divider unit refers to a voltage sampling network consisting of two resistors connected in series. It can be implemented using fixed-value resistors, with the voltage division coefficient set by the resistance ratio. This unit generates a control signal by detecting the external power input status, which directly affects the control terminal of the switching unit. The switching unit is a semiconductor device with voltage-controlled conduction characteristics, specifically implemented using a PMOS field-effect transistor. Its gate voltage determines the source-drain conduction state. When the voltage divider signal exceeds a threshold, the switching device automatically cuts off the battery power supply path. The voltage regulator module is a voltage conversion circuit, specifically implemented using a linear regulator or a DC-DC converter chip, used to convert the input voltage into a stable voltage value required by the load.

[0045] Specifically, when no external power is connected, the voltage divider unit has no voltage output, and the control terminal of the switching unit is in a low-level state, causing the switching device to conduct. At this time, the battery input terminal supplies power to the output node through the switching unit, and the current flows through the voltage regulator module to provide a stable voltage to the load. When an external power supply is connected, the voltage divider unit divides the input voltage, generating a sufficiently high voltage signal at the control terminal to turn off the switching device, thereby blocking the battery power supply path. The external power supply directly supplies power to the output node through the anti-backflow path, and after processing by the voltage regulator module, it supplies power to the load. The entire process requires no external control signal; the power path switching is achieved automatically only through passive components.

[0046] Compared to existing technologies, traditional solutions rely on active devices to generate control signals, while this solution achieves passive control through the direct interaction of a voltage divider network and switching devices, completely eliminating static current loss. Existing technologies require multiple control chips and logic circuits, while this solution uses only basic components such as resistors and MOSFETs, significantly simplifying the circuit structure and reducing manufacturing costs. Furthermore, the passive control method is unaffected by the microcontroller's initialization sequence or software faults, and maintains reliable operation even in low-temperature environments.

[0047] Through the above technical solution, this application can achieve automatic power path switching with zero quiescent current, avoiding unnecessary battery power loss in standby mode. The control loop is constructed using all passive components, effectively reducing system complexity and hardware costs. By directly controlling the state of the switching devices through a voltage divider signal, the battery circuit is quickly cut off when an external power source is connected, preventing reverse current from damaging the battery. This solution simplifies the circuit structure while significantly improving the reliability and environmental adaptability of power switching.

[0048] Reference Figures 2-3 This application further proposes a power switching circuit based on a body diode. The voltage divider unit includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the external power input terminal and the output node. The other end of the first resistor R1 is connected to one end of the second resistor R2 and forms a voltage divider output terminal. The other end of the second resistor R2 is grounded.

[0049] The voltage divider unit refers to a voltage sampling network consisting of two resistors connected in series. It can be implemented using surface-mount or thick-film resistors and is used to proportionally divide the voltage at the external power input and output it to the control terminal of the switching unit. The voltage divider output terminal is the connection point between the first resistor R1 and the second resistor R2, which generates a level signal related to the external power input voltage through the principle of resistor voltage division.

[0050] Specifically, when an external power source is connected to the input terminal, the voltage of the external power source forms a voltage divider circuit through the first resistor R1 and the second resistor R2. The voltage at the output terminal of the voltage divider is determined by the ratio of the resistance values ​​of the two resistors. This voltage divider signal is transmitted to the control terminal of the switching unit. When the voltage divider signal reaches a preset threshold, the switching unit is controlled to be in the off state. At this time, the power supply path to the battery input terminal is cut off, and the external power source supplies power to the output node through the anti-backflow path. When the external power source is not connected, the voltage divider output terminal is in a low-level state, the switching unit remains on, and the electrical energy at the battery input terminal is transferred to the output node through the switching unit.

[0051] This application further proposes that the battery input terminal has an input voltage of 3.7V and the external power supply input terminal has an input voltage of 5V.

[0052] The 3.7V input voltage at the battery input terminal refers to the battery's nominal operating voltage, which can be achieved using the typical voltage range of a single lithium-ion battery. This voltage range matches the battery's chemical characteristics and discharge platform. The 5V input voltage at the external power supply input terminal refers to the output voltage of the external charging power supply, which can be achieved using the standard USB power supply voltage or the adapter's output voltage. This voltage must be higher than the battery voltage to ensure reliable power switching. By setting the voltage difference between the battery and the external power supply, passive switching logic based on voltage comparison can be implemented without a control signal.

[0053] Specifically, when the external power input is not connected to a 5V power source, the 3.7V voltage at the battery input supplies power to the output node through the conducting switching unit. When the external power input is connected to a 5V power source, the voltage divider signal generated by the voltage divider unit causes the switching unit to turn off, and the external power supply directly supplies power to the output node through the anti-backflow path. The voltage difference between the two power sources creates a natural switching condition, allowing power path selection to be completed without relying on external control circuitry.

[0054] Reference Figure 4 This application further proposes that the switching unit includes a switching transistor Q1, which is a PMOS field-effect transistor. The gate of the switching transistor Q1 is connected to the voltage divider output terminal, the source of the switching transistor Q1 is connected to the output node, and the drain of the switching transistor Q1 is connected to the battery input terminal.

[0055] A PMOS field-effect transistor is a metal-oxide-semiconductor field-effect transistor that uses holes as charge carriers. It can be implemented using enhancement-mode PMOS devices, and its on / off state is controlled by the voltage difference between the gate and source. Connecting the gate to the voltage divider output terminal allows the gate potential to be adjusted via the voltage divider signal, thereby controlling the PMOS's on / off state. Connecting the source to the output node allows the source potential to dynamically change with the external power input state, and connecting the drain to the battery input terminal establishes the battery power supply path.

[0056] Specifically, when no external power is connected, there is no voltage signal at the voltage divider output. At this time, a sufficiently negative voltage difference is formed between the gate and source of the PMOS, causing the PMOS to conduct. Power from the battery input is then transferred to the output node via the drain-source path. When an external power supply is connected, a high-level signal is generated at the voltage divider output, making the gate potential higher than the source potential. The PMOS is then turned off due to insufficient gate-source voltage difference, thus cutting off the battery power supply path. This structure achieves power path switching through the voltage divider signal and the passive response of the PMOS, without relying on external control signals or logic circuits.

[0057] Compared to existing technologies, which require an MCU or comparator to generate control signals to drive the MOSFET, this solution directly utilizes a voltage divider signal and the gate characteristics of the PMOS to achieve automatic switching, eliminating the need for active control devices. For example, existing technologies require additional drive circuits or level conversion modules, while this solution can achieve control through a resistor divider network and the matching design of the PMOS, simplifying the circuit hierarchy.

[0058] This application further proposes that the resistance ratio of the first resistor R1 to the second resistor R2 be configured such that when the external power supply input voltage is 5V, the voltage at the voltage divider output terminal is controlled to be higher than the source voltage of the switching transistor Q1, thereby turning off the switching transistor Q1.

[0059] The resistance ratio refers to the ratio of the resistance values ​​of the first resistor R1 to the second resistor R2. Specifically, it can be achieved by using a combination of fixed resistors or adjustable resistors. By adjusting the resistance ratio, the voltage at the voltage divider output terminal can be changed.

[0060] Among them, voltage control at the voltage divider output terminal refers to proportionally reducing the voltage at the external power supply input terminal through a resistor voltage divider network. Specifically, this can be achieved through a series-connected resistor voltage divider circuit to ensure that the voltage after voltage division meets the level requirements of the switching transistor control terminal.

[0061] The cutoff condition of the switch Q1 refers to the gate-source voltage difference of the switch reaching the turn-off threshold when the voltage at the voltage divider output terminal is higher than the source voltage of the switch. This can be achieved through the threshold voltage characteristic of the PMOS field-effect transistor, so that the switch can be automatically turned off when an external power supply is connected.

[0062] Specifically, when a 5V voltage is applied to the external power input, the first resistor R1 and the second resistor R2 are connected in series to form a voltage divider circuit. The voltage at the output of the voltage divider is determined by the ratio of the two resistors. If the resistance ratio is set to 1:10, the output voltage is approximately 5V × (R2 / (R1+R2)), or approximately 4.55V. At this time, the source voltage of the switching transistor Q1 is close to 5V because the external power supply is directly supplied through diode D1, while the gate voltage is 4.55V. The gate-source voltage difference is negative and its absolute value exceeds the threshold voltage of the PMOS transistor, thus turning off the switching transistor Q1. As a result, the power supply path at the battery input is cut off, and the external power supply supplies power to the output node through diode D1, achieving passive switching of the power supply path.

[0063] Compared to existing technologies, traditional solutions rely on MCUs or comparators to generate control signals, which continuously consume quiescent current. This solution, however, directly controls the switching state through a resistor divider network and the threshold characteristics of the PMOS transistor, requiring no external active components and exhibiting no quiescent current in standby mode. Furthermore, while ideal diode chips or complex logic circuits in existing technologies are susceptible to low-temperature environments, this solution utilizes purely passive components, significantly improving its low-temperature resistance.

[0064] Reference Figure 5 This application further proposes to add a diode D1 between the external power input terminal and the output node. The anode of the diode D1 is connected to the external power input terminal and one end of the first resistor R1, and the cathode of the diode D1 is connected to the output node and the source of the switching transistor Q1.

[0065] In this design, diode D1 refers to a unidirectional conductive device, specifically a Schottky diode with a low forward voltage drop. Its anode is directly connected to the external power input terminal, and its cathode is connected to the output node, used to block reverse current from the external power supply to the battery input terminal. The voltage divider unit consists of a first resistor R1 and a second resistor R2 connected in series, specifically implemented using surface-mount resistors. The voltage threshold at the voltage divider output terminal is set by the resistance ratio, used to control the conduction state of the switching unit. The switching unit uses a PMOS field-effect transistor, specifically the conduction path between the drain and source is controlled by the difference between the gate voltage and the source voltage. When the voltage at the voltage divider output terminal is higher than the source voltage, the switching transistor is configured to be in the off state.

[0066] Specifically, when no external power is connected, there is no voltage signal at the voltage divider output terminal, and a conduction voltage difference is formed between the gate and source of the switching transistor Q1. The current at the battery input terminal flows to the output node through the switching transistor. When an external power supply is connected, the voltage divider unit divides the external power supply voltage and outputs it to the gate of the switching transistor Q1. At this time, the gate voltage is higher than the source voltage, the switching transistor Q1 is turned off, and the external power supply supplies power to the output node through diode D1. The cathode of diode D1 is directly connected to the output node, and the anode is connected to the external power supply input terminal. This forms a forward conduction path when an external power supply is present, while blocking the reverse current from the battery input terminal to the external power supply. The input terminal of the voltage regulator module is connected to the output node, and the internal circuit stabilizes the output voltage to a preset value.

[0067] Compared to existing technologies, current solutions rely on ideal diode chips or MOSFETs connected in reverse parallel to achieve reverse current protection, requiring control signals or complex drive circuits, which increases static power consumption. This solution uses a unidirectional diode and a voltage divider unit to work together to automatically cut off the battery power supply when an external power source is available. At the same time, it uses the unidirectional conductivity of the diode to passively block reverse current, eliminating the need for external control signals or dynamic adjustment devices, thus reducing circuit complexity and standby power consumption.

[0068] Through the above technical solution, this application achieves passive automatic switching between external power supply and battery power supply paths, effectively preventing voltage conflicts caused by reverse power flow into the battery input terminal and avoiding the power competition risk caused by abnormal control signals in traditional solutions. The introduction of diode D1 further simplifies the anti-reverse current circuit structure and maintains stable unidirectional conduction characteristics even in low-temperature environments, improving system reliability.

[0069] Reference Figures 2-5This application further proposes a voltage regulator module including a voltage regulator unit U1, capacitor C1, capacitor C2 and capacitor C3. One end of capacitor C3 is connected to the output node and the input terminal of voltage regulator unit U1. The other end of capacitor C3 is connected to the ground terminal of voltage regulator unit U1, one end of capacitor C2, one end of capacitor C1 and the common ground terminal. The other ends of capacitor C2 and capacitor C1 are connected to the output terminal of voltage regulator unit U1.

[0070] Among them, the voltage regulator unit U1 refers to the integrated circuit used to convert the input voltage into a stable output voltage. Specifically, it can be implemented by a low dropout linear regulator or a switching regulator chip. Its input terminal receives the fluctuating voltage from the output node and outputs a constant voltage through an internal regulation mechanism.

[0071] Among them, capacitor C3 refers to the filter capacitor set at the input end of the voltage regulator unit. Specifically, it can be implemented by electrolytic capacitor or ceramic capacitor, which is used to absorb high-frequency ripple of input voltage and suppress voltage surges during power switching.

[0072] Among them, capacitors C1 and C2 refer to decoupling capacitors connected in parallel at the output of the voltage regulator unit. Specifically, they can be implemented by combining multilayer ceramic capacitors and tantalum capacitors to filter out high-frequency noise at the output and maintain voltage stability during load changes.

[0073] Specifically, when an external power source is connected, it supplies power to the output node through an anti-backflow path. The voltage at the output node is initially filtered by capacitor C3 before being input to the voltage regulator unit U1. The voltage regulator unit U1 converts the fluctuating voltage into a preset regulated value, and then further filters out residual ripple at the output end through parallel capacitors C1 and C2, ultimately providing a stable voltage to the load. When switching to battery power, the battery voltage is transmitted to the output node via the switching unit. Similarly, the voltage is regulated through capacitor C3, the voltage regulator unit U1, and the filtering network composed of capacitors C1 and C2, ensuring that the load receives smooth and stable power in different power supply modes.

[0074] This application further proposes a charger, including a power switching circuit based on a body diode. The power switching circuit based on the body diode includes a battery input terminal, an external power input terminal, a voltage divider unit, a switching unit, and a voltage regulator module. The voltage divider unit is connected between the external power input terminal and ground to output a voltage divider signal. The switching unit controls the conduction state according to the voltage divider signal. The voltage regulator module converts the output node voltage into a preset voltage for the load.

[0075] Among them, the power switching circuit based on the body diode refers to a passive switching architecture built using the inherent body diode characteristics of semiconductor devices. Specifically, a PMOS field-effect transistor's body diode can be used as the current path, and the gate voltage of the switching transistor can be directly controlled through a resistor voltage divider network to achieve the switching of the conduction state. The voltage divider unit refers to a voltage sampling network composed of two series resistors, which can be implemented using a combination of surface-mount resistors. The gate potential of the switching transistor can be controlled by adjusting the resistance ratio. The switching unit refers to a semiconductor device with voltage-controlled conduction characteristics. Specifically, a PMOS transistor can be used as the switching element, utilizing its body diode to form an anti-backflow path in the off state.

[0076] Specifically, when no external power is connected, the voltage divider unit has no output voltage signal, and the voltage difference between the gate and source of the switching transistor is zero. At this time, the switching transistor is turned on, allowing battery power to supply power to the output node through the body diode of the switching transistor. When an external power supply is connected, the voltage divider unit outputs a gate control signal higher than the source voltage of the switching transistor, forcing the switching transistor to turn off. At the same time, the external power supply directly supplies power to the output node through the parallel diode. The voltage regulator module continuously receives power from the output node and converts it into a stable voltage, ensuring that the load power supply is not affected by the input source switching.

[0077] In some specific implementations, the resistance ratio of the two resistors in the voltage divider unit can be set to 1:10, for example, using a combination of 100kΩ and 10kΩ surface-mount resistors. The switching transistor can be an SOT-23 packaged PMOS device, with a body diode forward voltage drop of approximately 0.7V. A rectifier diode can be added between the external power input terminal and the output node, for example, an SMA packaged Schottky diode.

[0078] Compared to existing technologies, traditional solutions rely on an MCU to control a power management chip to generate an enable signal, requiring continuous quiescent current to maintain the control logic. This solution, however, achieves power switching through pure hardware circuitry, eliminating the need for any active components. Existing technologies use ideal diode chips, requiring external protection circuitry, while this solution directly utilizes the diode characteristics of the MOSFET to construct the current path, significantly reducing the number of components. In low-temperature environments, traditional MOSFET drive circuits may fail due to threshold voltage drift, while this solution directly controls the gate voltage through resistor voltage division, exhibiting stronger temperature adaptability.

[0079] Through the above technical solutions, this application effectively eliminates the static current loss of the control circuit, enabling the charger to operate with zero power consumption in standby mode. The use of passive components to construct the switching architecture avoids the risk of power conflicts caused by MCU malfunctions. By reducing the number of components and package size, material costs are significantly reduced and production yield is improved. The inherent characteristics of semiconductor devices are utilized to construct an anti-backflow path, ensuring power supply reliability under extreme temperature environments.

[0080] The above is only used to illustrate the technical solution of this utility model and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A power switching circuit based on a body diode, characterized in that, include: Battery input terminal, used for electrical connection to the battery; External power input terminal, used for electrical connection to an external charging power source; A voltage divider unit is connected between the external power input terminal and ground. The voltage divider output terminal of the voltage divider unit is used to divide the voltage of the external power input terminal and output a voltage divider signal. A switching unit, wherein the control terminal of the switching unit is connected to the voltage divider output terminal of the voltage divider unit, the first terminal of the switching unit is connected to the battery input terminal, and the second terminal of the switching unit is an output node; The voltage regulator module has its input terminal connected to the output node, and its output terminal is used to output a preset voltage to supply power to the load. The switching unit is turned on when no external power is connected to the external power input terminal, and turned off when an external power is connected to the external power input terminal. The voltage divider unit includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the external power input terminal and the output node. The other end of the first resistor R1 is connected to one end of the second resistor R2 and forms the voltage divider output terminal. The other end of the second resistor R2 is grounded. The switching unit includes a switching transistor Q1, which is a PMOS field-effect transistor. The gate of the switching transistor Q1 is connected to the voltage divider output terminal, the source of the switching transistor Q1 is connected to the output node, and the drain of the switching transistor Q1 is connected to the battery input terminal. A diode D1 is also provided between the external power input terminal and the output node. The anode of the diode D1 is connected to the external power input terminal and one end of the first resistor R1, and the cathode of the diode D1 is connected to the output node and the source of the switching transistor Q1.

2. The power switching circuit based on a body diode according to claim 1, characterized in that, The battery input terminal has an input voltage of 3.7V, and the external power supply input terminal has an input voltage of 5V.

3. The power switching circuit based on a body diode according to claim 2, characterized in that, The resistance ratio of the first resistor R1 to the second resistor R2 is configured such that when the external power supply input voltage is 5V, the voltage at the voltage divider output is controlled to be higher than the source voltage of the switch Q1, thereby turning off the switch Q1.

4. The power switching circuit based on a body diode according to claim 1, characterized in that, The voltage regulator module includes a voltage regulator unit U1, capacitor C1, capacitor C2, and capacitor C3. One end of capacitor C3 is connected to the output node and the input terminal of the voltage regulator unit U1, and the other end of capacitor C3 is connected to the ground terminal of the voltage regulator unit U1. One end of capacitor C2, one end of capacitor C1, and the other end of common ground capacitor C2 and capacitor C1 are connected to the output terminal of the voltage regulator unit U1.

5. The power switching circuit based on a body diode according to claim 4, characterized in that, The resistance ratio of the first resistor R1 to the second resistor R2 is 1:

10.

6. A charger, characterized in that, Includes a power switching circuit based on a body diode as described in any one of claims 1-5.

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