Power supply circuit, charging method and terminal equipment

Abstract

The invention provides a power supply circuit, a charging method and terminal equipment, and relates to the technical field of power supply circuits. The power supply circuit comprises a first battery, a second battery and a charging module; the voltage output end of the first battery is connected with the charging end of the second battery through the charging module; and the charging module is used for conducting a charging path between the first battery and the second battery when the terminal equipment is shut down, the output voltage of the first battery is greater than a first preset voltage, and the output voltage of the second battery is less than a second preset voltage, so that the first battery charges the second battery. According to the technical scheme, under the condition that the terminal equipment is powered off, the standby battery can still keep sufficient electric quantity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power supply circuit, in particular to a power supply circuit, a charging method and a terminal device. BACKGROUND

[0002] With the development of Internet of Things and intelligent manufacturing, the storage, logistics and other links of industrial products often use industrial PDA (Personal Digital Assistant) terminal devices to collect, archive and real-time input product information.

[0003] Generally, the industrial PDA terminal device uses a single main battery for power supply. When the main battery is low, the current main battery needs to be removed and another fully charged main battery needs to be inserted. In this process, the terminal device will temporarily lose power supply, causing the terminal device to power off, which will cause the collected data information to be unable to be uploaded to the terminal device in time, and even cause data loss.

[0004] Currently, when the terminal device changes the single battery, a backup battery is used to supply power to the PDA terminal device. Generally, the backup battery has small capacity, so it needs to ensure sufficient power. However, the current technical solution cannot ensure that the backup battery still has sufficient power when the terminal device is powered off. SUMMARY

[0005] The present application provides a power supply circuit, a charging method and a terminal device, which are used to provide a technical solution that the backup battery can still have sufficient power when the terminal device is powered off.

[0006] In a first aspect, the present application provides a power supply circuit for supplying power to a terminal device;

[0007] The circuit includes a first battery, a second battery and a charging module; the voltage output end of the first battery is connected to the charging end of the second battery through the charging module;

[0008] The charging module is used to turn on the charging path between the first battery and the second battery when the terminal device is powered off, the output voltage of the first battery is greater than the first preset voltage, and the output voltage of the second battery is less than the second preset voltage, so that the first battery charges the second battery.

[0009] The charging module is also used to turn off the charging path between the first battery and the second battery when the terminal device is powered off and the output voltage of the second battery is greater than or equal to the second preset voltage.

[0010] In an optional implementation, the circuit further includes a voltage detection module;

[0011] The first input terminal of the voltage detection module is connected to the voltage output terminal of the first battery, the second input terminal is connected to the voltage output terminal of the second battery, and the output terminal is connected to the enable terminal of the charging module;

[0012] The voltage detection module is used to control the charging module to turn on the charging path when the terminal device is turned off, the output voltage of the first battery is greater than a first preset voltage, and the output voltage of the second battery is less than a second preset voltage; the voltage detection module is also used to control the charging module to turn off the charging path when the output voltage of the second battery is boosted to greater than or equal to the second preset voltage.

[0013] In an optional embodiment, the voltage detection module includes a first voltage detection unit, and the first voltage detection unit includes a voltage detection subcircuit and a first switch;

[0014] The input end of the voltage detection subcircuit is connected to the voltage output end of the second battery, and the output end of the voltage detection subcircuit is connected to the control end of the first switch;

[0015] The input end of the first switch is connected to the voltage output end of the first battery, and the output end is connected to the enable end of the charging module;

[0016] The voltage detection subcircuit is configured to output a first signal and apply the first signal to the control terminal of the first switch when the terminal device is powered off and the voltage of the second battery is less than a second preset voltage; the first switch is configured to be opened under the control of the first signal, and the output voltage of the first battery is applied to the enable terminal of the charging module via the first switch, so that the charging module turns on the charging path;

[0017] The voltage detection subcircuit is also used to output a second signal and apply it to the control end of the first switch when the terminal device is turned off and the output voltage of the second battery is greater than or equal to a second preset voltage; the first switch is used to be turned off under the control of the second signal, and then the charging module turns off the charging path.

[0018] In an optional embodiment, the circuit further includes: a main control module;

[0019] The first output terminal of the main control module is connected to the enable terminal of the charging module;

[0020] When the terminal device is powered on, the first output terminal of the main control module outputs a high level, and the charging module turns on the charging path.

[0021] In an optional embodiment, the voltage detection module further includes a second switch;

[0022] The first input terminal of the main control module is connected to the charging detection signal terminal of the charging module, the second input terminal is connected to the output terminal of the voltage detection sub-circuit, and the second output terminal is connected to the control terminal of the second switch;

[0023] The input end of the second switch is connected to the low voltage end, and the output end is connected to the enable end of the charging module;

[0024] The main control module is configured to, when the terminal device is powered on, the charging detection signal terminal of the charging module outputs a high level, and the output terminal of the voltage detection sub-circuit outputs a high level, control the second switch to be turned on via a third signal outputted from the second output terminal, and the output terminal of the second switch to be turned off, so that the charging module shuts off the charging path;

[0025] The main control module is also used to, when the terminal device is turned on and the output end of the voltage detection sub-circuit outputs a low level, output a low level through the second output end, turn off the second switch, and output a high level to the enable end of the charging module through the first output end, so that the charging module turns on the charging path.

[0026] In an optional embodiment, the voltage detection module further includes a second voltage detection unit, and the second voltage detection unit includes: a third switch, and an AND gate subcircuit;

[0027] The control end of the third switch is connected to the charging detection signal end of the charging module, the input end is connected to the voltage output end of the second battery, and the output end is connected to the first input end of the AND gate sub-circuit;

[0028] The second input terminal of the AND gate sub-circuit is connected to the voltage output terminal of the first battery, and the output terminal is connected to the enable terminal of the charging module;

[0029] The third switch is configured to be turned on when the terminal device is powered on and the charging detection signal terminal of the charging module outputs a low level;

[0030] The AND gate sub-circuit is configured to output a high level to the enable terminal of the charging module when the third switch is turned on, so that the charging module turns on the charging path.

[0031] In an optional embodiment, the charging module includes a boost unit and a charging unit, the input end of the boost unit is connected to the voltage output end of the first battery, the output end of the boost unit is connected to the input end of the charging unit, and the enable end of the boost module is connected to the output end of the voltage detection module;

[0032] The output end of the charging unit is connected to the charging end of the second battery;

[0033] The enable terminal of the boost unit is the enable terminal of the charging module, and the enable terminal of the boost unit is used to control the on or off of the charging path;

[0034] The charging unit further includes a charging detection signal terminal. When the charging unit charges the second battery, the charging detection signal terminal outputs a low level. When the charging path is cut off, the charging detection signal terminal outputs a high level.

[0035] In an optional embodiment, the charging module further includes a buffer unit, one end of the buffer unit is grounded, and the other end is connected to the input end of the charging unit.

[0036] In a second aspect, an embodiment of the present application further provides a terminal device comprising the power supply circuit described in any one of the first aspects.

[0037] In a third aspect, an embodiment of the present application further provides a charging method, which is applied to a charging module of the power supply circuit described in any one of the first aspects, wherein the power supply circuit is used to charge a terminal device, and the power supply circuit includes a first battery, a second battery, and a charging module; the voltage output terminal of the first battery is connected to the charging terminal of the second battery through the charging module;

[0038] The method comprises:

[0039] When the terminal device is turned off and the output voltage of the first battery is greater than a first preset voltage and the output voltage of the second battery is less than a second preset voltage, a charging path between the first battery and the second battery is opened so that the first battery charges the second battery.

[0040] Under the circumstances of adopting the above-mentioned technical scheme, the embodiment of the present application provides a power supply circuit, a charging method and a terminal device. In the power supply circuit, when the terminal device is turned off, the output voltage of the first battery (main battery) is greater than the first preset voltage, indicating that the first battery has more power, while the output voltage of the second battery (backup battery) is less than the second preset voltage, indicating that the second battery is insufficient. At this time, the charging module conducts the charging path, so that the first battery charges the second battery, ensuring that the second battery is always in a state of sufficient power. For example, in an industrial-grade PDA, after the device is turned off and left for a period of time, when it is turned on again to replace the main battery, the second battery can provide stable power supply, avoiding the device being shut down due to the second battery being out of power, affecting the continuity of data collection and other tasks. Furthermore, the backup battery in the prior art may be exhausted when needed due to long-term non-charging, and cannot play the role of emergency power supply. The power supply circuit provided in the embodiment of the present application can enable the second battery to be replenished in time during the shutdown of the terminal device, significantly improving the availability of the second battery and increasing its reliability as an emergency power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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.

[0042] Figure 1 A circuit diagram of a charging circuit provided by an embodiment of the present invention Figure 1 ;

[0043] Figure 2 A circuit diagram of a charging circuit provided by an embodiment of the present invention Figure 2 ;

[0044] Figure 3 A circuit diagram of a charging circuit provided by an embodiment of the present invention Figure 3 ;

[0045] Figure 4 A circuit diagram of a charging circuit provided by an embodiment of the present invention Figure 4 ;

[0046] Figure 5 A schematic flow chart of a charging method provided by an embodiment of the present invention;

[0047] Figure 6 A schematic structural diagram of a terminal device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present invention.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. It will be understood that the terms "first", "second", etc. used in this application may be used herein to describe various information or data, but these elements are not limited by these terms. These terms are only used to distinguish the first information from another information. For example, without departing from the scope of this application, the first action information may be referred to as the second action information, and similarly, the second action information may be referred to as the first action information. Both the first action information and the second action information are action information, but they are not the same action information.

[0050] In this document, it should be understood that the terms involved are only used to facilitate understanding and do not represent any limitation on the meaning. In addition, the number of any element in the drawings is for illustration and not limitation, and any naming is only for distinction and does not have any limiting meaning.

[0051] The data involved in the present invention may be data authorized by the user or fully authorized by all parties, and the collection, dissemination, and use of the data shall comply with the requirements of relevant national laws and regulations.

[0052] With the development of the Internet of Things and intelligent manufacturing, industrial product warehousing, logistics and other links often use industrial-grade PDA (Personal Digital Assistant) terminal devices to collect, archive and enter product information in real time.

[0053] Typically, industrial-grade PDA terminals are powered by a single main battery. When the main battery runs low, you need to remove the current main battery and insert another fully charged main battery. During this process, the terminal device temporarily loses power, causing a power outage. This can delay the timely upload of collected data to the terminal device, and may even result in data loss.

[0054] Currently, when a single battery is replaced in a terminal device, a backup battery is used to power the PDA terminal device. The backup battery usually has a small capacity, so it needs to be sufficiently charged. However, the current technical solution cannot ensure that the backup battery remains sufficiently charged when the terminal device is turned off.

[0055] Based on this, the inventive concept of the embodiment of the present application is: when the terminal device is turned off, when the main battery has sufficient power and the backup battery has insufficient power, the main battery is used to charge the backup battery to ensure that the backup battery is always fully charged.

[0056] The technical solutions shown in this application are described in detail below through specific embodiments. It should be noted that the following embodiments can exist independently or in combination with each other, and the same or similar contents will not be repeated in different embodiments.

[0057] Figure 1 A power supply circuit is provided in an exemplary embodiment of the present application, and the power supply circuit is used to supply power to a terminal device.

[0058] Reference Figure 1 The power supply circuit includes a first battery 10, a second battery 20 and a charging module 30.

[0059] It is worth noting that in the embodiment of the present application, the first battery 10 can be a main battery, and the second battery 20 can be a backup battery. VBAT is the output voltage of the first battery, and VBACKUP is the output voltage of the second battery.

[0060] The capacities of the first battery 10 and the second battery 20 can be set according to actual needs, and the embodiment of the present application does not impose any special limitation on this.

[0061] For example, in the application scenario of an industrial PDA, the first battery needs to meet the requirements of long-term operation of the device. The capacity is usually large and can be set to 5000mAh to 10000mAh to support 8 to 12 hours of continuous operation of the device.

[0062] The second battery only needs to support the power consumption during the first battery replacement process (usually 1 to 5 minutes), and the capacity can be set to be smaller, such as 500mAh to 1000mAh, to reduce the weight and volume of the terminal device.

[0063] In the embodiment of the present application, the voltage output terminal 101 of the first battery 10 is connected to the charging terminal 201 of the second battery 20 through the charging module 30 .

[0064] The charging module 30 is used to conduct a charging path between the first battery 10 and the second battery 20 when the terminal device is turned off, the output voltage VBAT of the first battery 10 is greater than a first preset voltage, and the output voltage VBACKUP of the second battery 20 is less than a second preset voltage, so that the first battery 10 charges the second battery 20.

[0065] The first preset voltage is used to ensure that the first battery 10 has sufficient residual power to support the terminal device to boot next time after charging the second battery 20, and is also used to prevent the first battery 10 from being damaged due to over-discharge.

[0066] In one example, if the full-charge voltage of the first battery 10 is 4.2V (corresponding to 100% capacity), the discharge termination voltage is 3.0V (corresponding to 0% capacity, below which the battery can be damaged), and the commonly used working voltage interval is 3.7V-4.0V (corresponding to about 50%-90% capacity), the first preset voltage can be set to 3.6V-3.8V.

[0067] The selection of the first preset voltage is explained as follows.

[0068] 3.6V: corresponding to about 30% of the residual capacity of the first battery (at this time, after charging the second battery, the first battery still has more than 20% capacity, which is enough to support the terminal device to boot next time and run basic functions).

[0069] 3.8V: suitable for low-temperature environments or scenarios where the terminal device has high power consumption (such as industrial PDA starting RFID and strong light scanning functions), and reserves more power to prevent the first battery from over-discharging.

[0070] The second preset voltage can be understood as the charging voltage of the second battery 20. When the output voltage of the second battery 20 is less than the second preset voltage, it is considered that the second battery 20 can not be able to support a complete primary battery replacement process.

[0071] In one example, when the full-charge voltage of the second battery 20 is 4.2V (corresponding to 100% capacity), the second preset voltage can be set to 3.9V-4.0V.

[0072] The selection of the second preset voltage is explained as follows.

[0073] 3.9V: corresponding to about 70% of the residual capacity of the second battery (below this value, it can not be able to support a complete first battery replacement process and needs to be charged).

[0074] 4.0V: suitable for scenarios where the capacity of the second battery is small (such as 500mAh), and the power is replenished in advance to reserve redundancy (to prevent power failure due to operation timeout when replacing the primary battery).

[0075] Based on the above description, by setting the first preset voltage and the second preset voltage, the charging module can intelligently determine whether the second battery needs to be charged, avoiding unnecessary charging and protecting the service life of the second battery. Moreover, when the first battery also has low power, even if the second battery has insufficient power, charging will not be triggered, preventing the first battery from being damaged due to over-discharge.

[0076] When the above technical solution is adopted, when the terminal device is powered off, if the output voltage of the first battery (main battery) is greater than the first preset voltage, it indicates that the main battery still has a lot of power, while the output voltage of the second battery (backup battery) is less than the second preset voltage, indicating that the backup battery is low on power. At this time, the charging module opens the charging path, allowing the first battery to charge the second battery, ensuring that the second battery is always fully charged. For example, in an industrial-grade PDA, when the device is turned off for a period of time and then turned on again to replace the main battery, the second battery can provide stable power supply, avoiding the device shutting down due to a low second battery, which would affect the continuity of data collection and other tasks.

[0077] Furthermore, the backup battery in the prior art may be depleted when needed due to long periods of uncharging, making it unable to serve as an emergency power supply. The power supply circuit provided in the embodiments of the present application can enable the second battery to be replenished in a timely manner even when the terminal device is shut down, significantly improving the availability of the second battery and increasing its reliability as an emergency power supply.

[0078] Optionally, the charging module is further configured to cut off the charging path between the first battery and the second battery when the terminal device is powered off and the output voltage of the second battery is greater than or equal to the second preset voltage.

[0079] Based on this, on the one hand, overcharging of the second battery can be avoided, and on the other hand, sufficient power of the second battery can be ensured.

[0080] In an alternative embodiment, referring to Figure 2 The circuit also includes a voltage detection module 40; the first input terminal 401 of the voltage detection module 40 is connected to the voltage output terminal 101 of the first battery 10, the second input terminal 402 is connected to the voltage output terminal 201 of the second battery 20, and the output terminal 403 is connected to the enable terminal 301 of the charging module 30.

[0081] It should be understood that the enable terminal 301 of the charging module 30 is used to receive the output signal (typically a high or low level) from the voltage detection module 40 to determine whether to open the charging path. For example, when the output signal from the voltage detection module 40 received by the enable terminal 301 of the charging module 30 is a high level signal, the charging path is opened. When the output signal from the voltage detection module 40 received by the enable terminal 301 of the charging module 30 is a low level signal, the charging path is closed.

[0082] The voltage detection module 40 is used to control the charging module 30 to turn on the charging path when the terminal device is turned off, the output voltage VBAT of the first battery 10 is greater than a first preset voltage, and the output voltage VBACKUP of the second battery 20 is less than a second preset voltage.

[0083] The voltage detection module 40 is also configured to control the charging module 40 to turn off the charging path when the terminal device is powered off and the output voltage VBACKUP of the second battery 20 is greater than the second preset voltage.

[0084] In the embodiment of the present application, the voltage detection module 40 is configured to monitor the output voltage states of the first battery 10 and the second battery 20 in real time. When the second battery 20 is insufficient (VBACKUP< the second preset voltage) and the first battery 10 has sufficient power (VBAT> the first preset voltage), the first battery 10 is triggered to charge the second battery 20, so as to ensure that the second battery 20 is always in a state of having sufficient power.

[0085] Based on this, when the industrial PDA is powered off and stored for a period of time, there is no need to worry about the power loss of the second battery when it is used again. The first battery can be replaced seamlessly to avoid data loss or task interruption.

[0086] In addition, when the output voltage of the second battery 20 rises to the second preset voltage, the voltage detection module 40 controls the charging module 30 to turn off the charging path, so as to avoid the risk of capacity attenuation and bulging caused by the second battery being in a full power state for a long time, and prolong the cycle life of the second battery.

[0087] The voltage detection module in the embodiment of the present application can realize detection and judgment by using a pure hardware circuit, without relying on the main chip of the terminal device, so as to ensure that it can still work independently in a power-off state of the terminal device.

[0088] Optionally, referring to Figure 3 , the voltage detection module 40 includes a first voltage detection unit 41, and the first voltage detection unit 41 includes a voltage detection sub-circuit 411 and a first switch 412.

[0089] The input end of the voltage detection sub-circuit 41 is connected with the voltage output end of the second battery 20, configured to receive the signal VBACKUP output by the voltage output end of the second battery 20, and the output end of the voltage detection sub-circuit 411 is connected with the control end of the first switch 412.

[0090] The input end of the first switch 412 is connected with the voltage output end of the first battery 10, configured to receive the signal VBAT output by the voltage output end of the first battery 10, and the output end is connected with the enable end 301 of the charging module 30.

[0091] Optionally, the voltage detection sub-circuit 411 can be a voltage detection IC (integrated circuit). It should be understood that the voltage detection IC can also be referred to as a "voltage monitor" or a "voltage comparator, IC", which is a chip for detecting a voltage threshold.

[0092] Voltage detection ICs can use built-in reference voltage sources to avoid threshold deviations caused by temperature drift and error accumulation in discrete components.

[0093] For example, the voltage of the built-in reference voltage source of the voltage detection IC can be 3.8V, or 2.5V, or other required voltage values, which is not particularly limited in the embodiments of the present application.

[0094] Optionally, the voltage detection sub-circuit 411 may also be a comparison circuit based on an operational amplifier and a reference voltage source.

[0095] The voltage detection subcircuit 411 is used to output a first signal and apply it to the control end of the first switch 412 when the terminal device is turned off and the output voltage VBACKUP of the second battery 20 is less than a second preset voltage; the first switch 412 is used to open under the control of the first signal, and the output voltage VBAT of the first battery 10 is applied to the enable end 301 of the charging module 30 through the first switch 10, and the charging module 30 turns on the charging path.

[0096] The voltage detection subcircuit 411 is also used to output a second signal and apply it to the control end of the first switch 412 when the terminal device is turned off and the output voltage VBACKUP of the second battery 20 is greater than or equal to a second preset voltage; the first switch 412 is used to be turned off under the control of the second signal, and the charging module 30 turns off the charging path.

[0097] It should be understood that the type of the first switch described above is related to the output signal of the voltage detection subcircuit. When the first level is low, the first switch can be a PMOS switch. Based on this, when the output voltage VBACKUP of the second battery 20 is less than the second preset voltage, the voltage detection subcircuit outputs a low level, the first switch 412 turns on, and the output voltage of the first battery is applied to the enable terminal 301 of the charging module 30 through the first switch, and the charging module 30 turns on the charging path. When the output voltage VBACKUP of the second battery 20 is greater than or equal to the second preset voltage, the voltage detection subcircuit outputs a high level, the first switch 412 turns off, and the charging module 30 turns off the charging path.

[0098] When the first level is high, the first switch can be an NMOS switch tube. Based on this, when the output voltage VBACKUP of the second battery 20 is less than the second preset voltage, the voltage detection sub-circuit outputs a high level, the first switch 412 is turned on, and the output voltage of the first battery is applied to the enable end 301 of the charging module 30 through the first switch, so that the charging module 30 turns on the charging path. When the output voltage VBACKUP of the second battery 20 is greater than or equal to the second preset voltage, the voltage detection sub-circuit outputs a low level, the first switch 412 is turned off, and the charging module 30 turns off the charging path.

[0099] Based on the above description, automatic threshold judgment can be realized by the voltage detection sub-circuit 411 to ensure that the second battery can be charged when the output voltage is less than the second preset voltage and stopped when the output voltage is greater than or equal to the second preset voltage. The control process does not require manual intervention, and the cycle life of the second battery is significantly prolonged.

[0100] It should be understood that, when the terminal device is powered off, if the second battery is continuously charged, the power of the first battery 10 will be continuously consumed, which may cause the main battery to run out of power and the terminal device to fail to start. In the embodiment of the present application, only when the output voltage VBACKUP of the second battery is less than the second preset threshold, the first switch 412 is turned on and the charging module 30 works; otherwise (indicating that the second battery has sufficient power), the first switch 412 is turned off and the charging module 30 does not work, so that the first battery does not consume power.

[0101] Optionally, the first voltage detection unit 41 further comprises a first resistor R1 arranged between the output end of the voltage detection sub-circuit 411 and the output end of the first switch 412. The first resistor R1 can be used to limit the current flowing into the control end of the first switch 412 to avoid damage to the first switch due to overcurrent.

[0102] Optionally, the first voltage detection unit 41 further comprises a second resistor R2 arranged between the output end of the first switch and the output end of the first battery. The second resistor R2 can be used to attenuate the high voltage of the output voltage VBACKUP of the second battery or the output voltage VBAT of the first battery in proportion to ensure that the voltage detection sub-circuit 411 and the first switch tube 412 work in a safe voltage range.

[0103] Optionally, the first voltage detection unit 41 further comprises a first diode D1 arranged between the output end of the first switch 412 and the enable end 301 of the charging module 30. The first diode D1 is used to prevent the impact of reverse voltage (such as battery reverse connection and abnormal feedback of the charging module) on the first switch, and can also clamp the peak voltage to protect the circuit from surge damage.

[0104] Optionally, the circuit further comprises a master control module 50.

[0105] The master module 50 can be a master IC.

[0106] The first output end 503 of the master module 50 is connected to the enable end 301 of the charging module 30.

[0107] In the case that the terminal device is powered on, the signal SW_BOOST_EN output by the first output end 503 of the master module 50 is always high level, and the charging module 30 turns on the charging path.

[0108] Based on this, after the terminal device is powered on, the master module 50 outputs high level to the enable end 301 of the charging module 30, and turns on the charging path. At this time, whether the output voltage VBACKUP of the second battery 20 reaches the second preset threshold or not, the charging module 30 preferentially responds to the signal SW_BOOST_EN of the master module, and ensures the charging function of the second battery 20 in the powered-on state.

[0109] Optionally, the circuit further comprises a second diode D2 arranged between the first output end of the master module 50 and the enable end of the charging module 30, and the second diode D1 is used for preventing reverse voltage (such as battery reverse connection and abnormal feedback of the charging module) from impacting the master module, and at the same time, can clamp the peak voltage, and protect the circuit from surge damage.

[0110] In some optional embodiments, referring to Figure 3 , the voltage detection module 40 further comprises a second switch 431.

[0111] The first input end 501 of the master module 50 is connected to the charging detection signal end 304 of the charging module 30, the second input end 502 is connected to the output end of the voltage detection sub-circuit 411, and the second output end 502 is connected to the control end of the second switch 431.

[0112] The input end of the second switch 431 is connected to a low voltage end, and the output end is connected to the enable end 301 of the charging module 30.

[0113] The master module 50 is used for controlling the second switch 431 to turn on through the third signal SW_BOOST_CUTOFF output by the second output end 504 in the case that the terminal device is powered on, the charging detection signal end 304 of the charging module 30 outputs high level, and the output end of the voltage detection sub-circuit 411 outputs high level; and then, the output end of the second switch 403 outputs low level to the enable end 301 of the charging module 30, so that the charging module 30 turns off the charging path.

[0114] Based on the above description, the second switch 431 has an input connected to a low voltage terminal (e.g., GND or a fixed low voltage), an output connected to the enable terminal 301 of the charging module 30, and a control terminal controlled by the signal SW_BOOST_CUTOFF outputted by the second output terminal 504 of the main control module 50. When the second switch 431 is turned on, the enable terminal 301 of the charging module 30 is pulled to a low voltage, directly shutting off the charging path.

[0115] In the embodiment of the present application, when the charge detection signal terminal 304 outputs a high level and the voltage detection subcircuit 411 outputs a high level, the second switch 431 is turned on. The high level output from the charge detection signal terminal 304 indicates that the charging module 30 is no longer charging the second battery 20, and charging of the second battery 20 is complete. The high level output from the voltage detection subcircuit 411 indicates that the output voltage of the second battery 20 is greater than or equal to the second preset voltage, which also indicates that charging of the second battery 20 is complete. Therefore, the charging module 30 is used to directly shut off the charging path.

[0116] When the above technical solution is adopted, the charging detection signal terminal 304 and the output signal of the voltage detection subcircuit 411 are used to jointly determine whether to shut down the charging path, thereby improving the accuracy of the judgment. In other words, if only relying on the charging detection signal terminal 304, a malfunction of the charging module (such as a false alarm of "charging completed") may cause the second battery to be undercharged. If relying only on the output signal of the voltage detection circuit 411, it may be misjudged due to a battery failure (the voltage meets the standard but the actual capacity is insufficient).

[0117] The main control module 50 is further configured to output a low level through the second output terminal 504 when the terminal device is powered on and the signal VBACKUP_3.8V outputted from the output terminal 411 of the voltage detection sub-circuit is at a low level, thereby turning off the second switch 431 and outputting a high level to the enable terminal 301 of the charging module 30 through the first output terminal 503, thereby turning on the charging path.

[0118] The voltage detection subcircuit 411 outputs a low level (VBACKUP_3.8V is low), indicating that the output voltage of the second battery 20 is lower than the second preset voltage. At this point, the main control module 50 controls the charging path to conduct and promptly controls the charging of the second battery to avoid "under-battery delays." The second battery is used to provide a backup charging function for the terminal device. If the battery level is insufficient for a long time, the backup function may fail (e.g., data loss due to power outages). The above control logic determines whether the second battery is under-battery based on its output voltage and maintains the base charge level of the second battery.

[0119] Furthermore, the embodiment of the present application only opens the path when the second battery 20 is low on power, rather than continuously charging, thereby reducing the ineffective power consumption of the first battery (power supply end) and balancing the power replenishment demand with the energy saving goal.

[0120] Optional, see Figure 3 The voltage detection module further includes a second voltage detection unit 42 , and the second voltage detection unit 42 includes: a third switch 422 and an AND gate sub-circuit 421 .

[0121] The control end of the third switch 422 is connected to the charging detection signal end 304 of the charging module 304 , the input end is connected to the signal VBACKUP output by the voltage output end of the second battery 20 , and the output end is connected to the first input end of the AND gate circuit 421 .

[0122] The second input terminal of the AND gate sub-circuit 421 is connected to the voltage output terminal 101 of the first battery 10 , and the output terminal is connected to the enable terminal 301 of the charging module 30 .

[0123] The third switch 422 is configured to be turned on when the terminal device is powered on and the charging detection signal terminal 304 of the charging module 30 outputs a low level.

[0124] The third switch 422 may be a PMOS transistor. When the signal Charge_DET outputted by the charge detection signal terminal 304 of the charging module 304 is at a low level, the third switch 422 is turned on to transmit the signal VBACKUP outputted by the voltage output terminal of the second battery 20 to the first input terminal of the AND gate sub-circuit 421 .

[0125] The AND gate sub-circuit 421 may be a logic AND gate, or other circuits capable of implementing the above functions, and this embodiment of the present application does not impose any special limitation on this.

[0126] The low level of the signal Charge_DET outputted by the charging detection signal terminal 304 indicates that the charging module 30 is charging the second battery 20 .

[0127] The AND gate sub-circuit 421 is configured to output a high level to the enable terminal 301 of the charging module 30 when the third switch is turned on, so that the charging module 30 turns on the charging path.

[0128] It should be understood that the AND gate sub-circuit 421 will output a high level to the enable terminal 301 of the charging module 30 only when both the first input terminal and the second input terminal are connected to a high level.

[0129] In the embodiment of the present application, during the charging process of the second battery 20, the output voltage of the second battery 20 and the output voltage of the first battery 10 are high, but the charging detection signal terminal 304 of the charging module outputs a ground level. At this time, the charging path is turned on to charge the second battery.

[0130] Based on the above description, even if the output voltage of the second battery 20 rises to "high level" (close to full charge) during charging, as long as the second battery 20 is still in the charging state (Charge_DET is low), and the first battery 10 is normally charged, the charging module 30 will continue to turn on the charging path, avoid "premature interruption of charging" due to the rise of the output voltage of the second battery 20, and ensure that the second battery 20 can be charged to a sufficient state to meet the standby function requirements.

[0131] Optionally, the second voltage detection unit 42 further includes a third resistor R3 and a fourth resistor R4, the third resistor R3 is arranged between the charging detection signal end of the charging module 304 and the gate of the third switch 422, for current limiting protection of the gate of the third switch 422, and stabilizing the Charge_DET signal level, and resisting interference.

[0132] The fourth resistor R4 is arranged between the output end of the second battery and the first input end of the third switch 422, for voltage division protection of the input end of the AND gate, and isolation of the third switch and the AND gate, to avoid signal interference with each other.

[0133] Optionally, the second voltage detection unit 42 further includes a third diode D3 arranged between the output end of the AND gate 421 and the enable end 301 of the charging module 30, the third diode D3 is used for preventing reverse voltage (such as battery reverse connection, abnormal feedback of the charging module) from impacting the AND gate 421, and can also clamp the peak voltage to protect the circuit from surge damage.

[0134] In an optional embodiment, referring to Figure 4 , the charging module 30 includes a boost unit 31 and a charging unit 32, the input end 311 of the boost unit 31 is connected with the voltage output end 101 of the first battery 10, the output end 313 of the boost unit 31 is connected with the input end 321 of the charging unit 32, and the enable end 312 of the boost module 31 is connected with the output end 101 of the voltage detection module 40.

[0135] Wherein, the boost unit can be a boost IC, and the charging unit can be a charging IC.

[0136] The output end 322 of the charging unit 32 is connected with the charging end of the second battery 20.

[0137] Wherein, the enable end 312 of the boost unit 31 is the enable end of the charging module, and the enable end 312 of the boost unit 31 is used for controlling the turn-on or turn-off of the charging path.

[0138] The charging unit 32 further includes a charging detection signal terminal 323 . When the charging path is on, the signal Charge_DET output by the charging detection signal terminal 323 is at a low level. When the charging path is off, the signal Charge_DET output by the charging detection signal terminal 323 is at a high level.

[0139] The boost unit 31 is used to increase the output voltage of the first battery 10 to match the charging voltage of the second battery 20. For example, the output voltage of the first battery VBAT = 3.7V, after passing through the boost unit, the output voltage is 5V, which is suitable for the charging requirement of the second battery.

[0140] The power end of the boost unit 31 is connected to the output end of the voltage detection module 40 , and is used to control whether the boost unit 31 is working according to the output signal Charge_DET of the voltage detection end 323 .

[0141] The charging unit 32 receives the charging voltage matched to the second battery from the boost unit 31 and outputs the charging voltage to the second battery. The Charge_DET signal output by the charge detection signal terminal 323 provides other modules with the charging status of the charging unit. When the Charge_DET signal is low, the charging unit 32 is charging; when the Charge_DET signal is high, the charging unit 32 has stopped charging the second battery 20.

[0142] The embodiment of the present application uses a boost unit 31 to convert the output voltage of the first battery 10. This dynamically adjusts the output voltage to account for voltage fluctuations in the first battery 10 (e.g., a drop from 4.2V to 3.0V during discharge), ensuring that the voltage input to the charging unit 32 remains stable within the required charging voltage range of the second battery 20 (e.g., a stable 5V). Compared to "direct charging" (without boosting), this avoids the risk of battery capacity degradation or overcharging due to voltage instability, thereby extending the life of the second battery.

[0143] In addition, the embodiment of the present application concentrates the main switching function of the charging module at the enable terminal 312 of the boost unit 31, so that external control units such as the voltage detection module 40 and the main control module 50 can control the entire charging path through only one signal terminal (without having to control the boost and charging links separately), thereby simplifying the collaborative logic between multiple modules and reducing the complexity of circuit design.

[0144] Furthermore, the embodiment of the present application separates the functions of the boost unit 31 and the charging unit 32, and can then be independently debugged and optimized for boost efficiency and charging safety (such as adjusting the conversion efficiency of the boost unit or optimizing the protection threshold of the charging unit) without having to modify the entire circuit, thereby reducing costs.

[0145] Optionally, the charging module further comprises a buffer unit, one end of the buffer unit is grounded, and the other end is connected with the input end of the charging unit.

[0146] Wherein, referring to Figure 4 The buffer unit can be a capacitor C1, one end of the capacitor C1 is grounded, and the other end is connected with the input end of the charging unit 32.

[0147] In some examples, the buffer unit can also be other devices or circuits with the function of the buffer unit, and the embodiments of the present application do not make special limitations on this.

[0148] It should be understood that the input end of the charging unit 32 directly receives the output voltage of the voltage boosting unit 31, and when the voltage boosting unit is working, the output voltage can have periodic ripples due to the working of internal devices. In addition, the voltage of the first battery 10 can have a transient drop due to the change of device load (such as the sudden power consumption of other modules when the terminal is powered on), resulting in the instability of the input voltage of the charging unit.

[0149] Based on this, in the embodiments of the present application, when the input voltage of the charging unit 32 is higher than the average value, the capacitor C1 charges to absorb excess energy, avoiding voltage spikes; when the input voltage of the charging unit 32 is lower than the average value, the capacitor C1 can discharge to the charging unit 32 to release the stored energy to fill the voltage trough.

[0150] And at the moment when the charging path is just turned on, the charging unit 32 enters the working state from the standby state, which can generate a large instantaneous impact current. If this current directly acts on the semiconductor devices inside the charging unit, it can exceed the rated current bearing capacity of the device, resulting in overheating damage or life attenuation. At this time, the capacitor C1 is used to absorb part of the current (by fast charging) to reduce the instantaneous current peak value flowing into the internal devices of the charging unit; after the charging path is stable, the capacitor C1 releases the energy smoothly by slow discharge, and cooperates with the voltage boosting unit 31 to provide continuous current.

[0151] This dynamic adjustment can control the input voltage fluctuation of the charging unit 32 within a very small range (such as reducing the ripple amplitude from hundreds of millivolts to tens of millivolts), ensuring that the core modules such as the reference circuit and the current detection circuit inside the charging unit work in a stable voltage environment, avoiding the instability of the charging current, the decline of the charging efficiency or the incomplete charging of the battery due to the voltage fluctuation.

[0152] The overall scheme provided by the embodiments of the present application will be described below by using a specific embodiment:

[0153] Referring to Figure 4, VBAT is the output voltage of the first battery 10 (the following description assumes that the first battery 10 is charged and the VBAT output is high). VBACKUP is the output voltage of the second battery 10. When VBACKUP is greater than 3.8V, the voltage detection sub-circuit 411 (hereinafter referred to as the voltage detection IC) outputs a high-impedance state, and the first switch 412 (hereinafter referred to as PMOS1) is cut off; when the VBACKUP voltage is less than 3.8V, the voltage detection IC output is low, and PMOS1 is turned on. When the charging unit 32 (hereinafter referred to as the charging IC) is in the charging state, Charge_DET is low, the third switch 422 (hereinafter referred to as PMOS2) is turned on, and the AND gate sub-circuit 421 (also referred to as a logic AND gate) outputs high. Conversely, when the charging IC is in the non-charging state, Charge_DET is high, the power switch PMOS2 is cut off, and the AND gate sub-circuit output is low. If any one of the outputs of SW_BOOST_5V_EN, PMOS1, and the AND gate sub-circuit is high, the boost unit 31 (hereinafter referred to as the boost IC) outputs 5V to charge the second battery 20 through the charging IC.

[0154] When the terminal device is powered off, the VBAT output from the voltage output terminal of the first battery 10 is high, SW_BOOST_5V_EN is low, and SW_BOOST_5V_CUTOFF is also low. If the VBACKUP voltage is less than 3.8V, the voltage detection IC output is low, PMOS1 turns on, the boost IC outputs 5V, and the charging IC charges the second battery 20. As the VBACKUP voltage of the second battery 20 gradually increases to greater than 3.8V while charging, the voltage detection IC output is high, PMOS1 turns off, and since it takes time for capacitor C1 at the charging IC input to discharge, Charge_DET remains low, PMOS2 turns on, the logic AND gate output is high, the boost IC outputs 5V, and the charging IC charges the second battery 20, completing the entire charging cycle. After charging is complete, Charge_DET is high, PMOS2 turns off, the logic AND gate output is low, the boost IC does not output 5V, and the charging IC does not charge the second battery 20, thus entering a low-power state.

[0155] When the terminal device is powered off, the voltage output terminal VBAT of the first battery 10 is high, SW_BOOST_5V_EN is low, and SW_BOOST_5V_CUTOFF is also low. If the VBACKUP voltage is greater than 3.8V, the voltage detection IC output is high, PMOS1 is turned off, and the boost IC enable is pulled low. The boost IC does not output 5V, and the charging IC does not charge the second battery 20, and the mobile terminal enters a low-power state.

[0156] The main reasons for detecting whether the output voltage VBACKUP of the second battery 20 is greater than 3.8V are:

[0157] When the output voltage VBACKUP of the second battery 20 is greater than 3.8V, the power of the second battery 20 is sufficient to maintain the power supply of the first battery 10 during the battery replacement process. Setting the second battery 20 with a voltage less than 3.8V to be shut down and charged can ensure that the second battery 20 has stable power supply during the battery replacement process of the first battery 10 of the mobile terminal.

[0158] When the mobile terminal is shipped, the output voltage of the second battery 20 is greater than 3.8V, and the charging IC does not charge the second battery 20 to avoid the first battery 10 boosting the voltage to charge the second battery 20, which causes high power consumption of the mobile terminal and prevents misjudgment of abnormal power consumption of the mobile terminal.

[0159] When the terminal device is turned on, the signal SW_BOOST_5V_EN outputted by the first output terminal 503 of the main control module 50 (hereinafter referred to as the main control IC) is high level, the boost IC outputs 5V, the charging IC charges the second battery 20, and completes the entire charging cycle.

[0160] When the terminal device is turned on, when the main control IC detects that Charge_DET is high and VBACKUP_3V8 is high, the SW_BOOST_5V_CUTOFF output by the first output terminal is high, pulling down the enable terminal of the boost IC, the boost IC does not output 5V, and the charging IC stops charging the second battery 20.

[0161] When the terminal device is powered on, if the main control IC detects that VBACKUP_3V8 is low, SW_BOOST_5V_CUTOFF outputs a low level, turning off the second switch 412 (also known as NMOS). SW_BOOST_5V_EN always outputs a high level, the boost IC outputs 5V, and the charging IC charges the second battery 20, completing the entire charging cycle.

[0162] When the terminal device is turned on, the main control IC can determine whether the second battery 20 is in a charging state by detecting the level of Charge_DET and notify the user interface. That is, when Charge_DET is low, the second battery 20 is in a charging state; when Charge_DET is high, the second battery 20 is in a non-charging state.

[0163] In a second aspect, the embodiment of the present application further provides a terminal device, including the terminal device in the first aspect. Figures 1 to 4 The charging circuit in.

[0164] The terminal device provided in the embodiment of the present application includes the above-mentioned power supply circuit. When the terminal device is turned off, the output voltage of the first battery (main battery) is greater than the first preset voltage, indicating that the first battery has more power, and the output voltage of the second battery (backup battery) is less than the second preset voltage, indicating that the second battery is insufficient. At this time, the charging module turns on the charging path, so that the first battery charges the second battery, ensuring that the second battery is always in a state of sufficient power. For example, in an industrial-grade PDA, after the device is turned off and left for a period of time, when it is turned on again to replace the main battery, the second battery can provide stable power supply, avoiding the device being shut down due to the second battery being out of power, affecting the continuity of data collection and other tasks. Furthermore, the backup battery in the prior art may be exhausted when needed due to long-term non-charging, and cannot play the role of emergency power supply. The power supply circuit provided in the embodiment of the present application can enable the second battery to be replenished in time during the shutdown of the terminal device, significantly improving the availability of the second battery and increasing its reliability as an emergency power supply.

[0165] Thirdly, refer to Figure 5 , an embodiment of the present application provides a charging method, which is applied to the charging module of the power supply circuit described in the first aspect, wherein the power supply circuit is used to charge the terminal device, and the power supply circuit includes a first battery, a second battery, and a charging module; the voltage output terminal of the first battery is connected to the charging terminal of the second battery through the charging module;

[0166] The method comprises:

[0167] S501, when the terminal device is powered off and the output voltage of the first battery is greater than a first preset voltage and the output voltage of the second battery is less than a second preset voltage, conduct a charging path between the first battery and the second battery so that the first battery charges the second battery.

[0168] S502: When the terminal device is powered off and the output voltage of the second battery is greater than or equal to the second preset voltage, cut off the charging path between the first battery and the second battery.

[0169] In this power supply method, when the terminal device is turned off, the output voltage of the first battery (main battery) is greater than the first preset voltage, indicating that the first battery has more power, while the output voltage of the second battery (backup battery) is less than the second preset voltage, indicating that the second battery is insufficient. At this time, the charging module turns on the charging path, so that the first battery charges the second battery, ensuring that the second battery is always in a state of sufficient power. For example, in an industrial-grade PDA, after the device is turned off and left for a period of time, when it is turned on again to replace the main battery, the second battery can provide stable power supply, avoiding the device being shut down due to the second battery being out of power, affecting the continuity of data collection and other tasks. Furthermore, the backup battery in the prior art may be exhausted when needed due to long-term non-charging, and cannot play the role of emergency power supply. The power supply method provided in the embodiment of the present application can enable the second battery to be replenished in time during the shutdown of the terminal device, significantly improving the availability of the second battery and increasing its reliability as an emergency power supply.

[0170] Fourthly, Figure 6 This is a schematic diagram of the structure of an electronic device provided by an exemplary embodiment of the present application. Figure 6 The terminal device 700 may include a processor 701 and a memory 702. Exemplarily, the processor 701 and the memory 702 are interconnected via a bus 703.

[0171] The memory 702 stores computer-executable instructions;

[0172] The processor 701 executes the computer-executable instructions stored in the memory 702 , so that the processor 701 performs the method shown in the above method embodiment.

[0173] Figure 6 The terminal device shown may be the near-eye display device or wearable terminal device described in any of the above embodiments.

[0174] Accordingly, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the method described in the above method embodiment.

[0175] Accordingly, an embodiment of the present application may also provide a computer program product, including a computer program, which, when executed by a processor, may implement the method shown in the above method embodiment.

[0176] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0177] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0178] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0179] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0180] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0181] Memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0182] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0183] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0184] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power supply circuit, characterized in that: Used to power terminal equipment; The circuit includes a first battery, a second battery and a charging module; the voltage output end of the first battery is connected to the charging end of the second battery through the charging module; The charging module is configured to, when the terminal device is powered off and the output voltage of the first battery is greater than a first preset voltage and the output voltage of the second battery is less than a second preset voltage, conduct a charging path between the first battery and the second battery so that the first battery charges the second battery; The charging module is further configured to cut off the charging path between the first battery and the second battery when the terminal device is powered off and the output voltage of the second battery is greater than or equal to the second preset voltage.

2. The circuit according to claim 1, wherein: The circuit also includes a voltage detection module; The first input terminal of the voltage detection module is connected to the voltage output terminal of the first battery, the second input terminal is connected to the voltage output terminal of the second battery, and the output terminal is connected to the enable terminal of the charging module; The voltage detection module is used to control the charging module to turn on the charging path when the terminal device is turned off, the output voltage of the first battery is greater than a first preset voltage, and the output voltage of the second battery is less than a second preset voltage; the voltage detection module is also used to control the charging module to turn off the charging path when the output voltage of the second battery is boosted to greater than or equal to the second preset voltage.

3. The circuit according to claim 2, characterized in that The voltage detection module includes a first voltage detection unit, and the first voltage detection unit includes a voltage detection subcircuit and a first switch; The input end of the voltage detection subcircuit is connected to the voltage output end of the second battery, and the output end of the voltage detection subcircuit is connected to the control end of the first switch; The input end of the first switch is connected to the voltage output end of the first battery, and the output end is connected to the enable end of the charging module; The voltage detection subcircuit is configured to output a first signal and apply the first signal to the control terminal of the first switch when the terminal device is powered off and the voltage of the second battery is less than a second preset voltage; the first switch is configured to be opened under the control of the first signal, and the output voltage of the first battery is applied to the enable terminal of the charging module via the first switch, so that the charging module turns on the charging path; The voltage detection subcircuit is also used to output a second signal and apply it to the control end of the first switch when the terminal device is turned off and the output voltage of the second battery is greater than or equal to a second preset voltage; the first switch is used to be turned off under the control of the second signal, and then the charging module turns off the charging path.

4. The circuit according to claim 3, characterized in that The circuit further comprises: a main control module; The first output terminal of the main control module is connected to the enable terminal of the charging module; When the terminal device is powered on, the first output terminal of the main control module outputs a high level, and the charging module turns on the charging path.

5. The circuit according to claim 4, characterized in that The voltage detection module further includes a second switch; The first input terminal of the main control module is connected to the charging detection signal terminal of the charging module, the second input terminal is connected to the output terminal of the voltage detection sub-circuit, and the second output terminal is connected to the control terminal of the second switch; The input end of the second switch is connected to the low voltage end, and the output end is connected to the enable end of the charging module; The main control module is configured to, when the terminal device is powered on, the charging detection signal terminal of the charging module outputs a high level, and the output terminal of the voltage detection sub-circuit outputs a high level, control the second switch to be turned on via a third signal outputted from the second output terminal, and the output terminal of the second switch to be turned off, so that the charging module shuts off the charging path; The main control module is also used to, when the terminal device is turned on and the output end of the voltage detection sub-circuit outputs a low level, output a low level through the second output end, turn off the second switch, and output a high level to the enable end of the charging module through the first output end, so that the charging module turns on the charging path.

6. The circuit according to claim 3, characterized in that The voltage detection module further includes a second voltage detection unit, and the second voltage detection unit includes: a third switch, and an AND gate subcircuit; The control end of the third switch is connected to the charging detection signal end of the charging module, the input end is connected to the voltage output end of the second battery, and the output end is connected to the first input end of the AND gate sub-circuit; The second input terminal of the AND gate sub-circuit is connected to the voltage output terminal of the first battery, and the output terminal is connected to the enable terminal of the charging module; The third switch is configured to be turned on when the terminal device is powered on and the charging detection signal terminal of the charging module outputs a low level; The AND gate sub-circuit is configured to output a high level to the enable terminal of the charging module when the third switch is turned on, so that the charging module turns on the charging path.

7. The circuit according to any one of claims 2 to 6, characterized in that: The charging module includes a boost unit and a charging unit, the input end of the boost unit is connected to the voltage output end of the first battery, the output end of the boost unit is connected to the input end of the charging unit, and the enable end of the boost module is connected to the output end of the voltage detection module; The output end of the charging unit is connected to the charging end of the second battery; The enable terminal of the boost unit is the enable terminal of the charging module, and the enable terminal of the boost unit is used to control the on or off of the charging path; The charging unit further includes a charging detection signal terminal. When the charging unit charges the second battery, the charging detection signal terminal outputs a low level. When the charging path is cut off, the charging detection signal terminal outputs a high level.

8. The circuit according to claim 7, characterized in that The charging module further includes a buffer unit, one end of which is grounded, and the other end of which is connected to the input end of the charging unit.

9. A terminal device, characterized in that: The power supply circuit comprises the power supply circuit according to any one of claims 1 to 8.

10. A charging method, characterized in that: A charging module applied to a power supply circuit according to any one of claims 1 to 8, wherein the power supply circuit is used to charge a terminal device, and the power supply circuit comprises a first battery, a second battery, and a charging module; The voltage output terminal of the first battery is connected to the charging terminal of the second battery through the charging module; The method comprises: When the terminal device is powered off and the output voltage of the first battery is greater than a first preset voltage and the output voltage of the second battery is less than a second preset voltage, a charging path between the first battery and the second battery is opened so that the first battery charges the second battery; When the terminal device is powered off and the output voltage of the second battery is greater than or equal to the second preset voltage, the charging path between the first battery and the second battery is cut off.

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