An automatic switching circuit between external power supply and battery power supply for portable equipment

Abstract

The present invention relates to an automatic switching circuit between an external power supply and battery power supply of a portable device, which comprises a first switch component, a second switch component, a third switch component, a charging management module and a power management module; one end of the first switch component is connected to the input end of the external power supply, and the other end is connected to the device load; one end of the second switch component and the third switch component are both connected to the power management module, and the power management module is connected to a rechargeable battery; the other end of the second switch component is connected to the device load, and the other end of the third switch component is connected to the charging management module, and the input end of the charging management module is connected to the external power supply. The present invention uses an ideal diode switch circuit designed with a PMOS tube to replace the power supply combining diode and the anti-reverse diode of the charging management circuit, which solves the voltage drop problem caused by the diode, improves the use efficiency of the rechargeable battery, and increases the service life of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply circuits, and in particular to an automatic switching circuit between an external power supply and a battery for power supply of a portable device. Background Art

[0002] Portable devices generally need to support both internal battery power supply and external power supply. The basic process of using external power supply and internal battery power supply is as follows: when the external power supply is connected, the external power supply not only needs to power the portable device, but also needs to charge the built-in rechargeable battery; when the external power supply is removed, it needs to seamlessly switch to the built-in rechargeable battery to power the device.

[0003] Usually, due to the change of the position of the portable device, the external power supply and the internal battery power supply are often switched alternately. The switching of the two power supply modes is usually done by combining the external power supply and the internal battery through a diode, and using the unidirectional conduction characteristics of the diode to achieve power supply switching. However, there is a voltage drop when the diode is unidirectional, which causes energy loss when the battery is discharged, thereby shortening the battery's single charge time. In addition, in order to avoid leakage of the battery to the charging management circuit when there is no external power supply, a common measure is to add a diode device between the charging management circuit and the battery. Due to the voltage drop of the diode device, the introduction of the diode device will cause the battery to be unable to be fully charged during charging, resulting in the battery capacity cannot be fully utilized. The above two points have led to an increase in the frequency of battery charging, and currently various types of rechargeable batteries have a limit on the number of cycle charging and discharging. For example, the number of cycle charging and discharging of 18650 lithium-ion batteries and polymer lithium-ion batteries is generally around 500 times. Therefore, how to reduce the number of cycle charging and discharging of rechargeable batteries as much as possible to provide the service life of the built-in battery of portable devices, thereby extending the battery life, is what needs to be considered at this stage. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, provide an automatic switching circuit between an external power supply and a battery for a portable device, and solve the defect of frequently charging a rechargeable battery.

[0005] The objective of the present invention is achieved through the following technical scheme: a portable device external power supply and battery power supply automatic switching circuit, which comprises a first switch component, a second switch component, a third switch component, a charging management module and a power management module; one end of the first switch component is connected to the input end of the external power supply, and the other end is connected to the device load; one end of the second switch component and the third switch component are both connected to the power management module, and the power management module is connected to the rechargeable battery; the other end of the second switch component is connected to the device load, and the other end of the third switch component is connected to the charging management module, and the input end of the charging management module is connected to the external power supply.

[0006] The first switch component includes a unidirectional ideal diode switch composed of two PMOS tubes Q1 and Q2, which is used to control the switching off and on of the path from the external power supply to the device load; the second switch component includes a unidirectional ideal diode switch composed of two PMOS tubes Q5 and Q6, which is used to control the switching off and on of the path from the built-in rechargeable battery to the device load; the third switch component includes a unidirectional ideal diode switch composed of a PMOS tube Q4, which is used to control the switching off and on of the built-in rechargeable battery to the charging management module.

[0007] The drain of Q1 in the first switch component is connected to the output end of the external power supply, the source of Q1 is connected to the source of Q2, the drain of Q2 is connected to the device load, the gate of Q1 is connected to the gate of Q4 in the third switch component, the gate of Q1 is controlled by the external power supply through the inversion result of Q3, and the gate of Q2 is controlled by the line AND result of the external power on / off button signal of the device and the power-on hold signal of the device through the inversion of Q7.

[0008] The source of Q5 in the second switch component is connected to the source of Q6, the drain of Q6 is connected to the device load, the gate of Q6 is connected to the gate of Q2, and is controlled by the line AND result of the external power on / off button signal of the device and the power-on hold signal of the device inverted by Q7, the drain of Q5 is connected to the power management module and the source of Q4 in the third switch component, and the gate of Q5 is controlled by the external power input.

[0009] The drain of Q4 in the third switch component is connected to the output of the charging management module, the gate of Q4 is connected to the gate of the first switch component Q1, and the source of Q4 is connected to the drain of the second switch component Q5.

[0010] It includes first, second, third and fourth working modes; the first working mode is the circuit default state, the second working mode realizes battery charging and the device is powered by an external power supply, the third working mode only realizes battery charging, and the fourth working mode realizes the device is powered by a battery.

[0011] In the first working mode, there is no external power supply, the device power-on control signal is invalid, the third switch component is turned off, the second switch component is turned off, Q5 is turned on, Q6 is turned off, the first switch component is turned off, Q1 and Q2 are both turned off, and the device is in the shutdown state.

[0012] In the second working mode, there is an external power supply and the device power-on control signal is valid, the third switch component is turned on, the second switch component is turned off, Q5 is turned off, Q6 is turned on, and the first switch component is turned on. At this time, the device load is powered by the external power supply, and the external power supply charges the built-in rechargeable battery through the charging management module.

[0013] In the third working mode, there is an external power supply and the device power-on control signal is invalid. At this time, the third switch component is turned on, the second switch component is turned off, and the first switch component is turned off, wherein Q1 is turned on and Q2 is turned off, the device is in the shutdown state, and the external power supply charges the built-in rechargeable battery through the charging management module.

[0014] In the fourth working mode, there is no external power supply, and the device power on / off control signal is valid. At this time, the third switch component is turned off, the second switch component is turned on, and the first switch component is turned off, wherein Q1 is turned off and Q2 is turned on, and the device load is powered by the built-in rechargeable battery power supply VBAT, while cutting off the leakage path from VBAT to the external power supply and the charging management module.

[0015] The present invention has the following advantages: a portable device external power supply and battery power supply automatic switching circuit, using a PMOS tube designed ideal diode switch circuit to replace the power supply circuit diode and the anti-reverse diode of the charging management circuit, effectively solving the voltage drop problem caused by the diode. Avoid unnecessary battery loss when the battery is powered, ensure that the battery can be fully charged when the external power supply is connected, thereby improving the use efficiency of the rechargeable battery and increasing the battery life; can conveniently realize the automatic switching control of the external power supply and internal battery power supply of the portable device; when it is detected that the portable device is connected to the external power supply, it automatically and seamlessly switches to the external power supply to power the load, and cuts off the path from the internal battery to the load; when it is detected that the portable device has no external power supply, it automatically and seamlessly switches to the path from the internal battery to the load, and cuts off the leakage path of the external power supply and the battery charging management module. Therefore, the battery loss is avoided when there is an external power supply, and the unnecessary leakage loss of the battery is eliminated when there is no external power supply. The circuit structure is simple and reliable, the control is flexible and convenient, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention;

[0017] Figure 2 is a circuit diagram of the present invention;

[0018] Figure 3 is a schematic diagram of current flow in the second working mode of the present invention;

[0019] Figure 4 is a schematic diagram of current flow in the third working mode of the present invention;

[0020] Figure 5 Schematic diagram of current flow in the fourth working mode of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the drawings is not intended to limit the scope of protection of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0022] like Figure 1 As shown, the present invention relates to an automatic switching circuit between an external power supply and battery power supply of a portable device, which comprises a first switch component, a second switch component, a third switch component, a charging management module and a power management module; one end of the first switch component is connected to the input end of the external power supply, and the other end is connected to the device load; one end of the second switch component and the third switch component are both connected to the power management module, and the power management module is connected to a rechargeable battery; the other end of the second switch component is connected to the device load, and the other end of the third switch component is connected to the charging management module, and the charging management module is connected to the input end of the external power supply.

[0023] like Figure 2 As shown, Q1 is the front-end PMOS tube of switch 1, Q2 is the back-end PMOS tube of switch 1; Q4 is the PMOS tube of switch 3; Q5 is the front-end PMOS tube of switch 2, and Q6 is the back-end PMOS tube of switch 2; U3 is a dedicated chip for the charging management module; U2 is a dedicated chip for the power management module; J1 is the built-in battery of the device; VIN is connected to the external power output; VOUT is connected to the device load; VBAT is the output power of the built-in battery; KEY is the external power button signal of the device, and the low level is valid; POWER_CTR is the power-on hold signal of the device, and the high level is valid.

[0024] Furthermore, the first switch component includes a unidirectional ideal diode switch composed of two PMOS tubes Q1 and Q2, which is used to control the shutoff and opening of the path from the external power supply to the device load; the second switch component includes a unidirectional ideal diode switch composed of two PMOS tubes Q5 and Q6, which is used to control the shutoff and opening of the path from the built-in rechargeable battery to the device load; the third switch component includes a unidirectional ideal diode switch composed of a PMOS tube Q4, which is used to control the shutoff and opening of the built-in rechargeable battery to the charging management module.

[0025] Furthermore, the drain of Q1 in the first switch component is connected to the output end of the external power supply, the source of Q1 is connected to the source of Q2, the drain of Q2 is connected to the device load, the gate of Q1 is connected to the gate of Q4 in the third switch component, the gate of Q1 is controlled by the external power supply through the inversion result of Q3, and the gate of Q2 is controlled by the line AND result of the external power on / off button signal of the device and the power-on hold signal of the device through the inversion of Q7.

[0026] Furthermore, the source of Q5 in the second switch component is connected to the source of Q6, the drain of Q6 is connected to the device load, the gate of Q6 is connected to the gate of Q2, and is controlled by the line AND result of the external power on / off button signal of the device and the power-on hold signal of the device inverted by Q7, the drain of Q5 is connected to the power management module and the source of Q4 in the third switch component, and the gate of Q5 is controlled by the external power input.

[0027] Furthermore, the drain of Q4 in the third switch component is connected to the output of the charging management module, the gate of Q4 is connected to the gate of the first switch component Q1, and the source of Q4 is connected to the drain of the second switch component Q5.

[0028] The first working mode of the present invention is: this working state or working mode is the circuit default state, there is no external power supply (VIN = 0V), and the portable device power-on control signal is invalid (Key is suspended or POWER_CTR is low level). At this time, switch 3 is closed, and its PMOS tube (Vgs voltage of Q4 in the circuit diagram = 0V) is closed; switch 2 is closed, its front-end PMOS (Vgs of Q5 in the circuit diagram = -VBAT) is turned on, and the back-end PMOS tube (Vgs voltage of Q6 in the circuit diagram = 0V) is turned off; switch 1 is closed, and its front-end PMOS (Vgs voltage of Q1 in the circuit diagram = 0V) and back-end PMOS (Vgs voltage of Q2 in the circuit diagram = 0V) are both in the off mode. Therefore, the device is in the off state, the paths from the battery to the charging management module and to the device load are disconnected, and the built-in battery has basically no energy loss.

[0029] like Figure 3As shown, the second working mode of the present invention is: there is an external power supply, and the portable device power-on key signal is valid (Key is low level, or POWER_CTR is high level). At this time, switch 3 is turned on, and its PMOS tube (Vgs voltage of Q4 in the circuit diagram = -VBAT) is turned on; switch 2 is turned off, its front-end PMOS is turned off (Vgs of Q5 in the circuit diagram = VIN-VBAT>0), and the back-end PMOS tube (Vgs voltage of Q6 in the circuit diagram = -VIN) is turned on; switch 1 is turned on, its front-end PMOS tube (Vgs voltage of Q1 in the circuit diagram = -VIN) is turned on, and the back-end PMOS tube (Vgs voltage of Q2 in the circuit diagram = -VIN) is also turned on; so the portable device load is powered by the external power supply VIN, and the external power supply charges the built-in battery through the charging management module.

[0030] like Figure 4 As shown, the third working mode of the present invention is: there is an external power supply, and the power-on key signal of the portable device is invalid (Key is suspended or POWER_CTR is low). At this time, switch 3 is turned on, and its PMOS tube (Vgs voltage of Q4 in the circuit diagram = -VBAT) is turned on; switch 2 is turned off, and its front-end PMOS tube (Vgs of Q5 in the circuit diagram = VIN-VBAT>0) is turned off, and the back-end PMOS tube (Vgs voltage of Q6 in the circuit diagram = 0) is turned off; switch 1 is turned off, and the front-end PMOS tube (Vgs voltage of Q1 in the circuit diagram = -VIN) is turned on, and the back-end PMOS tube (Vgs voltage of Q2 in the circuit diagram = 0) is turned off; therefore, the portable device is in the off state, the device load is not working, and the external power supply charges the built-in battery through the charging management module.

[0031] like Figure 5 As shown, the fourth working mode of the present invention is: there is no external power supply, and the portable device power-on key signal (Key is low level, or POWER_CTR is high level) is valid. At this time, switch 3 is closed, and its PMOS tube (Vgs voltage of Q4 in the circuit diagram = 0V) is closed; switch 2 is opened, its front-end PMOS (Vgs of Q5 in the circuit diagram = -VBAT) is turned on, and the back-end PMOS tube of switch 2 (Vgs voltage of Q6 in the circuit diagram = -VBAT) is turned on; switch 1 is closed, its front-end PMOS tube (Vgs voltage of Q1 in the circuit diagram = 0V) is turned off, and the back-end PMOS tube of switch 1 (Vgs voltage of Q2 in the circuit diagram = -VBAT) is turned on. Therefore, the portable device load is powered by the built-in battery power VBAT, and at the same time, the leakage path from VBAT to the external power supply and the charging management module is cut off.

[0032] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A circuit for automatically switching between external power supply and battery power supply for a portable device, characterized in that: It includes a first switch component, a second switch component, a third switch component, a charging management module and a power management module; one end of the first switch component is connected to the input end of an external power supply, and the other end is connected to a device load; one end of the second switch component and the third switch component are both connected to the power management module, and the power management module is connected to a rechargeable battery; the other end of the second switch component is connected to the device load, and the other end of the third switch component is connected to the charging management module, and the input end of the charging management module is connected to the external power supply; The first switch component includes a unidirectional ideal diode switch composed of two PMOS tubes Q1 and Q2, which is used to control the switching off and on of the path from the external power supply to the device load; the second switch component includes a unidirectional ideal diode switch composed of two PMOS tubes Q5 and Q6, which is used to control the switching off and on of the path from the built-in rechargeable battery to the device load; the third switch component includes a unidirectional ideal diode switch composed of a PMOS tube Q4, which is used to control the switching off and on of the built-in rechargeable battery to the charging management module; It includes first, second, third and fourth working modes; the first working mode is the circuit default state, the second working mode realizes battery charging and the device is powered by an external power supply, the third working mode only realizes battery charging, and the fourth working mode realizes the device is powered by a battery; In the first working mode, there is no external power supply, the device startup control signal is invalid, the third switch component is turned off, the second switch component is turned off, Q5 is turned on, Q6 is turned off, the first switch component is turned off, Q1 and Q2 are both turned off, and the device is in the shutdown state; In the second working mode, there is an external power supply, and the device power-on control signal is valid, the third switch component is turned on, the second switch component is turned off, Q5 is turned off, Q6 is turned on, and the first switch component is turned on. At this time, the device load is powered by the external power supply, and the external power supply charges the built-in rechargeable battery through the charging management module; In the third working mode, there is an external power supply, and the device power-on control signal is invalid. At this time, the third switch component is turned on, the second switch component is turned off, and the first switch component is turned off, wherein Q1 is turned on, Q2 is turned off, and the device is in a shutdown state. The external power supply charges the built-in rechargeable battery through the charging management module; In the fourth working mode, there is no external power supply, and the device power on / off control signal is valid. At this time, the third switch component is turned off, the second switch component is turned on, and the first switch component is turned off, wherein Q1 is turned off and Q2 is turned on, and the device load is powered by the built-in rechargeable battery power supply VBAT, while cutting off the leakage path from VBAT to the external power supply and the charging management module.

2. The automatic switching circuit between external power supply and battery power supply of a portable device according to claim 1, characterized in that: The drain of Q1 in the first switch component is connected to the output end of the external power supply, the source of Q1 is connected to the source of Q2, the drain of Q2 is connected to the device load, the gate of Q1 is connected to the gate of Q4 in the third switch component, the gate of Q1 is controlled by the external power supply through the inversion result of Q3, and the gate of Q2 is controlled by the line AND result of the external power on / off button signal of the device and the power-on hold signal of the device through the inversion of Q7.

3. The automatic switching circuit between external power supply and battery power supply of a portable device according to claim 1, characterized in that: The source of Q5 in the second switch component is connected to the source of Q6, the drain of Q6 is connected to the device load, the gate of Q6 is connected to the gate of Q2, and is controlled by the line AND result of the external power on / off button signal of the device and the power-on hold signal of the device inverted by Q7, the drain of Q5 is connected to the power management module and the source of Q4 in the third switch component, and the gate of Q5 is controlled by the external power input.

4. The automatic switching circuit between external power supply and battery power supply of a portable device according to claim 1, characterized in that: The drain of Q4 in the third switch component is connected to the output of the charging management module, the gate of Q4 is connected to the gate of the first switch component Q1, and the source of Q4 is connected to the drain of the second switch component Q5.

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