USB port control circuit and portable energy storage device

Abstract

The utility model provides a USB port control circuit and a portable energy storage device, the circuit comprises a step-down output circuit, a USB output circuit and an overcurrent protection control circuit, a controllable end of the step-down output circuit is used for being connected with a control end of a single-chip microcomputer, the USB output circuit comprises a plurality of USB output sub-circuits, and the overcurrent protection control circuit is connected with the control end of the single-chip microcomputer. The plurality of USB output sub-circuits are connected in series and are connected to the output end of the step-down output circuit; the number of the over-current protection control circuits is multiple, each over-current protection control circuit is correspondingly connected to the grounding end of each USB output sub-circuit, each over-current protection control circuit comprises a first control tube, a first resistor, a second resistor and a third resistor, and under the condition that a hardware total over-current protection threshold value is not changed, when a plurality of USB output ports are used at the same time, the over-current protection control circuits are connected to the grounding ends of the USB output sub-circuits. And if the on-load total current exceeds the total overcurrent protection threshold value, the current of the most recently used USB output port is cut off, so that the connection state of the power connection equipment can be flexibly controlled, and the use requirements of different equipment are met.

Description

Technical Field

[0001] The present disclosure relates to the technical field of portable energy storage, and particularly to a USB port control circuit and a portable energy storage device. Background Art

[0002] Generally, the common USB charger on the market has a power of 12W (5V 2.4A), which can support most mobile phones or mobile power devices. Therefore, when designing USB ports on mobile portables and mobile power supplies, this is usually used as the standard. In terms of the circuit, the designed overcurrent protection value is only slightly larger than 2.4A. Since this USB port is a hardware solution without a protocol, the electrical appliance will not adjust according to the maximum current. When used for some electrical appliances with a charging power of 15W (5V 3A) or larger, overcurrent protection will be triggered and normal charging cannot be carried out.

[0003] In addition, even if there are multiple USB ports, when a device with a 15W charging power is connected to any one of the USB ports, the situation of triggering overcurrent protection will also occur. Moreover, some portable energy storage devices only support loads with a limited power (such as 12W). Therefore, it is impossible to meet the types of devices that require charging with more USB ports. Summary of the Utility Model

[0004] The purpose of the present disclosure is to overcome the deficiencies in the prior art, and to provide a USB port control circuit and a portable energy storage device that can support more types of devices for USB port charging and can flexibly control the connection status of the connected devices.

[0005] The purpose of the present disclosure is achieved through the following technical solutions:

[0006] A USB port control circuit includes:

[0007] A buck output circuit for stepping down the input voltage and outputting it. The controllable end of the buck output circuit is used to connect to the control end of a single-chip microcomputer, so that the single-chip microcomputer records the total current state of the buck output circuit;

[0008] A USB output circuit includes a plurality of USB output sub-circuits. The plurality of USB output sub-circuits are connected in series and connected to the output end of the buck output circuit;

[0009] Overcurrent protection control circuit, the number of the overcurrent protection control circuits is multiple and equal to the number of the USB output sub - circuits. Each of the overcurrent protection control circuits is correspondingly connected to the ground terminal of each of the USB output sub - circuits. The overcurrent protection control circuit includes a first control tube, a first resistor, a second resistor and a third resistor. The first end of the first control tube is connected to the ground terminal of the USB output sub - circuit. The second end of the first control tube is respectively connected to the first end of the second resistor and the first end of the third resistor. The control end of the first control tube is used to be connected to the enable end of the single - chip microcomputer through the first resistor. The second end of the second resistor is used to be connected to the acquisition end of the single - chip microcomputer. The second end of the third resistor is connected to the negative power supply terminal.

[0010] In one embodiment, the overcurrent protection control circuit further includes a fourth resistor. The first end of the fourth resistor is connected to the second end of the first control tube, and the second end of the fourth resistor is connected to the control end of the first control tube.

[0011] In one embodiment, the overcurrent protection control circuit further includes a second control tube. The first end of the second control tube is connected to the ground terminal of the USB output sub - circuit. The second end of the second control tube is connected to the first end of the fourth resistor, and the control end of the second control tube is connected to the second end of the fourth resistor.

[0012] In one embodiment, the number of the USB output sub - circuits is three, namely a first USB output sub - circuit, a second USB output sub - circuit and a third USB output sub - circuit. Each of the overcurrent protection control circuits is respectively correspondingly connected to the ground terminals of the first USB output sub - circuit, the second USB output sub - circuit and the third USB output sub - circuit.

[0013] In one embodiment, the USB port control circuit further includes a first bidirectional voltage - stabilizing diode. The upper half - end of the first bidirectional voltage - stabilizing diode is connected to the power - receiving terminal of the first USB output sub - circuit, and the lower half - end of the first bidirectional voltage - stabilizing diode is grounded.

[0014] In one embodiment, the USB port control circuit further includes a second bidirectional voltage - stabilizing diode. The upper half - end of the second bidirectional voltage - stabilizing diode is connected to the power - receiving terminal of the second USB output sub - circuit, and the lower half - end of the second bidirectional voltage - stabilizing diode is grounded.

[0015] In one embodiment, the USB port control circuit further includes a third bidirectional voltage - stabilizing diode. The upper half - end of the third bidirectional voltage - stabilizing diode is connected to the power - receiving terminal of the third USB output sub - circuit, and the lower half - end of the third bidirectional voltage - stabilizing diode is grounded.

[0016] In one embodiment, the USB port control circuit further includes a voltage stabilizing capacitor. The upper end of the voltage stabilizing capacitor is connected to the output end of the buck output circuit, and the lower end of the voltage stabilizing capacitor is grounded.

[0017] In one embodiment, the USB port control circuit further includes a fourth bidirectional voltage stabilizing diode. The first end of the fourth bidirectional voltage stabilizing diode is connected to the upper end of the voltage stabilizing capacitor, and the second end of the fourth bidirectional voltage stabilizing diode is grounded.

[0018] A portable energy storage device includes the USB port control circuit according to any one of the above embodiments.

[0019] Compared with the prior art, the present disclosure has at least the following advantages:

[0020] In the USB port control circuit, the overcurrent protection threshold of a single USB port is set to 3.3A, which can adapt to more types of devices charged by USB ports (such as devices with a charging power of 12W, 15W, etc.). Without changing the total overcurrent protection threshold of the hardware, that is, the total overcurrent protection threshold of multiple USB output ports, when multiple USB output ports are used simultaneously and the voltage of a single USB output port is lower than the single-port overcurrent protection threshold, if the total load current exceeds the total overcurrent protection threshold, the single-chip microcomputer disconnects the current of the most recently used USB output port according to the recorded insertion and use time of each USB port, so as to flexibly control the connection state of the powered devices and meet the usage requirements of different devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present disclosure, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a circuit diagram of the USB port control circuit in one embodiment;

[0023] Figure 2 For Figure 1 It is a circuit diagram of the buck output circuit in the USB port control circuit shown;

[0024] Figure 3 For Figure 1 It is a partial circuit diagram of the USB port control circuit shown;

[0025] Figure 4 For Figure 1 It is a circuit diagram of the overcurrent protection control circuit in the USB port control circuit shown;

[0026] Figure 5 It is the structural diagram of a single-chip microcomputer in an embodiment.

[0027] Reference numerals: 10, USB port control circuit; 100, step-down output circuit; 200, USB output circuit; 210, first USB output sub-circuit; 220, second USB output sub-circuit; 230, third USB output sub-circuit; 300, overcurrent protection control circuit; Q1A, first control transistor; Q1B, second control transistor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; TVS27, first bidirectional voltage regulator diode; TVS28, second bidirectional voltage regulator diode; TVS29, third bidirectional voltage regulator diode; TVS6, fourth bidirectional voltage regulator diode; C30, voltage stabilizing capacitor; U2, single-chip microcomputer. Specific embodiments

[0028] To facilitate the understanding of the present disclosure, the present disclosure will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the understanding of the disclosure content of the present disclosure is more thorough and comprehensive.

[0029] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this disclosure belongs. The terms used herein in the description of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] To better understand the technical solutions and beneficial effects of the present disclosure, the present disclosure will be further described in detail below with reference to specific embodiments:

[0032] Please refer to Figures 1 to 4 , which is the USB port control circuit 10 of an embodiment of the present invention, including a step-down output circuit 100, a USB output circuit 200, and an overcurrent protection control circuit 300.

[0033] The step-down output circuit 100 is used to step down the input voltage and output it. Specifically, it converts the 24V input voltage into a 5V output voltage. The controllable end of the step-down output circuit 100 is used to connect to the control end of the single-chip microcomputer U2, so that the single-chip microcomputer U2 records the total current state of the step-down output circuit 100. Among them, the enable end USB-EN of the step-down output circuit 100 is connected to the enable control end of the single-chip microcomputer U2, and the controlled end USB 5V-DET of the step-down output circuit 100 is connected to the total current acquisition end of the single-chip microcomputer U2.

[0034] The USB output circuit 200 includes multiple USB output sub-circuits, and the multiple USB output sub-circuits are connected in series and connected to the output end of the step-down output circuit 100. In this embodiment, the total current state of the step-down output circuit 100 recorded by the single-chip microcomputer U2 is the sum of the currents of each USB output sub-circuit.

[0035] The number of overcurrent protection control circuits 300 is multiple and is equal to the number of USB output sub-circuits. As Figure 3 shown, each overcurrent protection control circuit 300 is correspondingly connected to the grounding end of each USB output sub-circuit. As Figure 4 shown, each overcurrent protection control circuit 300 includes a first control transistor Q1A, a first resistor R1, a second resistor R2, and a third resistor R3. The first end of the first control transistor Q1A is connected to the grounding end of the USB output sub-circuit. The second end of the first control transistor Q1A is respectively connected to the first end of the second resistor R2 and the first end of the third resistor R3. The control end of the first control transistor Q1A is used to connect to the enable end of the single-chip microcomputer U2 through the first resistor R1. The second end of the second resistor R2 is used to connect to the acquisition end of the single-chip microcomputer U2, and the second end of the third resistor R3 is connected to the negative power supply.

[0036] In this embodiment, in the USB port control circuit 10, the overcurrent protection threshold of a single USB port is set to 3.3A, which can adapt to more types of devices charging through USB ports (such as devices with a charging power of 12W, 15W, etc.). Without changing the total hardware overcurrent protection threshold, that is, the total overcurrent protection threshold of multiple USB output ports, when multiple USB output ports are used simultaneously and the voltage of a single USB output port is lower than the single-port overcurrent protection threshold, if the total load current exceeds the total overcurrent protection threshold, the single-chip microcomputer U2 disconnects the current of the most recently used USB output port according to the insertion and use time of each USB port, so as to be able to flexibly control the connection state of the powered devices and meet the usage requirements of different devices.

[0037] In this embodiment, as Figure 3As shown, the number of USB output sub - circuits is three, namely the first USB output sub - circuit 210, the second USB output sub - circuit 220, and the third USB output sub - circuit 230. Each over - current protection control circuit 300 is respectively connected to the ground terminals of the first USB output sub - circuit 210, the second USB output sub - circuit 220, and the third USB output sub - circuit 230.

[0038] Specifically, the first USB output sub - circuit 210, the second USB output sub - circuit 220, and the third USB output sub - circuit 230 are all connected to the enable terminals of the single - chip microcomputer U2 (i.e., the USB - EN1 terminal, USB - EN2 terminal, and USB - EN3 terminal of the single - chip microcomputer U2) through the over - current protection control circuit 300, and the first USB output sub - circuit 210, the second USB output sub - circuit 220, and the third USB output sub - circuit 230 are all connected to the acquisition terminals of the single - chip microcomputer U2 (i.e., the I - load1 / AD terminal, I - load2 / AD terminal, and I - load3 / AD terminal of the single - chip microcomputer U2) through the over - current protection control circuit 300, so that the single - chip microcomputer U2 can collect the current conditions of the first USB output sub - circuit 210, the second USB output sub - circuit 220, and the third USB output sub - circuit 230, and determine whether to enable the conduction of the first control transistor Q1A of any over - current protection control circuit 300 according to whether the current exceeds the USB single - port over - current protection threshold. As Figures 2 to 5 shown, the first USB output sub - circuit 210 is respectively connected to the first enable terminal USB - EN1 and the first acquisition terminal I - load1 / AD of the single - chip microcomputer U2 through the over - current protection control circuit 300, the second USB output sub - circuit 220 is respectively connected to the second enable terminal USB - EN2 and the second acquisition terminal I - load2 / AD of the single - chip microcomputer U2 through the over - current protection control circuit 300, and the third USB output sub - circuit 230 is respectively connected to the third enable terminal USB - EN3 and the third acquisition terminal I - load3 / AD of the single - chip microcomputer U2 through the over - current protection control circuit 300.

[0039] As Figure 2 shown, when the USB port control circuit 10 is powered on, the input voltage of 24V is stepped down to 5V by the step - down output circuit 100 and output to the USB output circuit 200. At this time, the single - chip microcomputer U2 collects the current of a single USB port and records the current state of the single USB port. As Figure 3 and Figure 5As shown, the overcurrent protection threshold of the single USB port is 3.3A. When a device is connected to the single USB port, if any single USB port exceeds this protection threshold, the microcontroller U2 triggers overcurrent protection according to the state of the first control transistor Q1A of any overcurrent protection control circuit 300, and cuts off the current output of this USB port. At the same time, the microcontroller U2 traverses the currents of the USB ports in a loop, records the total current of all USB ports. If a device has been connected to a USB port at this time, it records the access time, so as to determine one of the USB ports as the most recently accessed USB port. When multiple devices are connected to the USB ports and working, if the total current of all USB ports exceeds the maximum total current protection threshold of 7.6A, according to the access time of the USB ports recorded by the microcontroller U2, the most recently accessed USB port is cut off to stop the device from working, and the normal output of other USB ports is maintained. When the total current of all USB ports is lower than 4.3A, the output of the most recently accessed USB port is automatically restored, so that the circuit can achieve overcurrent protection and can also flexibly control the state of the device when it is connected to the USB port.

[0040] As Figure 4 shown, in one embodiment, the overcurrent protection control circuit 300 further includes a fourth resistor R4. The first end of the fourth resistor R4 is connected to the second end of the first control transistor Q1A, and the second end of the fourth resistor R4 is connected to the control end of the first control transistor Q1A. It can be understood that when the current of a USB port exceeds the single-port overcurrent protection threshold, the microcontroller U2 enables a signal to the first control transistor Q1A of the corresponding connected overcurrent protection control circuit 300. Since the first resistor R1 and the fourth resistor R4 are in series, the first resistor R1 and the fourth resistor R4 divide the voltage, ensuring conduction in the state where any single USB port exceeds the single-port overcurrent protection threshold, so that the level of the USB port is pulled low, thereby disconnecting the current output of the USB port.

[0041] As Figure 4As shown, in one embodiment, the overcurrent protection control circuit 300 further includes a second control transistor Q1B. The first end of the second control transistor Q1B is connected to the ground terminal of the USB output sub-circuit, specifically, the ground terminals of the first USB output sub-circuit 210, the second USB output sub-circuit 220, and the third USB output sub-circuit 230. The second end of the second control transistor Q1B is connected to the first end of the fourth resistor R4, and the control end of the second control transistor Q1B is connected to the second end of the fourth resistor R4. Among them, when multiple overcurrent protection control circuits 300 are respectively connected to the ground terminals of the first USB output sub-circuit 210, the second USB output sub-circuit 220, and the third USB output sub-circuit 230, the first control transistor Q1A and the second control transistor Q1B form a double-group control transistor (Q15, Q16, and Q17). Among them, the double-group control transistor Q15 is used to control the on / off state of the first USB output sub-circuit 210, the double-group control transistor Q16 is used to control the on / off state of the second USB output sub-circuit 220, and the double-group control transistor Q17 is used to control the on / off state of the third USB output sub-circuit 230.

[0042] In this embodiment, both the first control transistor Q1A and the second control transistor Q1B are NMOS transistors. The first end 1 of the first control transistor Q1A is the drain, the second end 2 is the source, and the control end 3 is the gate; the first end 4 of the second control transistor Q1B is the drain, the second end 5 is the source, and the control end 6 is the gate. The two NMOS transistors (i.e., the first control transistor Q1A and the second control transistor Q1B) form a double-group NMOS field effect transistor (corresponding to Figure 3 the double-group control transistors Q15, Q16, and Q17).

[0043] As Figure 3 shown, in one embodiment, the USB port control circuit 10 further includes a first bidirectional voltage stabilizing diode TVS27. The upper half of the first bidirectional voltage stabilizing diode TVS27 is connected to the power connection terminal of the first USB output sub-circuit 210, and the lower half of the first bidirectional voltage stabilizing diode TVS27 is grounded. It can be understood that in the state where the double-group control transistor Q15 is disconnected, when a device is connected to the USB port of the first USB output sub-circuit 210, the device operates normally, and the first bidirectional voltage stabilizing diode TVS27 is used to stabilize the voltage to prevent the voltage from suddenly changing and damaging the device.

[0044] As Figure 3As shown, in one embodiment, the USB port control circuit 10 further includes a second bidirectional voltage stabilizing diode TVS28. The upper end of the second bidirectional voltage stabilizing diode TVS28 is connected to the power receiving end of the second USB output sub-circuit 220, and the lower end of the second bidirectional voltage stabilizing diode TVS28 is grounded. It can be understood that in the state where the double-group control transistor Q16 is disconnected, when a device is connected to the USB port of the second USB output sub-circuit 220, the device operates normally, and the second bidirectional voltage stabilizing diode TVS28 is used to stabilize the voltage and avoid the situation of voltage mutation damaging the device.

[0045] As Figure 3 Shown, in one embodiment, the USB port control circuit 10 further includes a third bidirectional voltage stabilizing diode TVS29. The upper end of the third bidirectional voltage stabilizing diode TVS29 is connected to the power receiving end of the third USB output sub-circuit 230, and the lower end of the third bidirectional voltage stabilizing diode TVS29 is grounded. It can be understood that in the state where the double-group control transistor Q17 is disconnected, when a device is connected to the USB port of the third USB output sub-circuit 230, the device operates normally, and the third bidirectional voltage stabilizing diode TVS29 is used to stabilize the voltage and avoid the situation of voltage mutation damaging the device.

[0046] As Figure 3 Shown, in one embodiment, the USB port control circuit 10 further includes a voltage stabilizing capacitor C30. The upper end of the voltage stabilizing capacitor C30 is connected to the output end of the buck output circuit 100, and the lower end of the voltage stabilizing capacitor C30 is grounded. It can be understood that when the output voltage reaches the USB output circuit 200, in order to ensure that the output voltage can enable the USB output circuit 200 to operate, the voltage stabilizing capacitor C30 is used to absorb static electricity, avoid the situation of voltage mutation damaging circuit components, and can also filter the output voltage to reduce the interference of unstable signals.

[0047] As Figure 3 Shown, in one embodiment, the USB port control circuit 10 further includes a fourth bidirectional voltage stabilizing diode TVS6. The first end of the fourth bidirectional voltage stabilizing diode TVS6 is connected to the upper end of the voltage stabilizing capacitor C30, and the second end of the fourth bidirectional voltage stabilizing diode TVS6 is grounded. It can be understood that the voltage stabilizing capacitor C30 and the fourth bidirectional voltage stabilizing diode are connected in parallel and grounded together, which can jointly suppress the signal interference caused by the fluctuation of the output voltage and avoid voltage mutation.

[0048] The present disclosure also provides a portable energy storage device, including the USB port control circuit 10 according to any one of the above embodiments.

[0049] Compared with the prior art, the present disclosure has at least the following advantages:

[0050] In the USB port control circuit 10, the overcurrent protection threshold of a single USB port is set at 3.3 A, which can adapt to more types of devices charged by USB ports (such as devices with a charging power of 12 W, 15 W, etc.). Without changing the total hardware overcurrent protection threshold, that is, the total overcurrent protection threshold of multiple USB output ports, when multiple USB output ports are used simultaneously and the voltage of a single USB output port is lower than the single-port overcurrent protection threshold, if the total load current exceeds the total overcurrent protection threshold, the single-chip microcomputer U2 disconnects the current of the most recently used USB output port according to the insertion and use time of each USB port, so as to be able to flexibly control the connection state of the powered devices and meet the usage requirements of different devices.

[0051] The above-described embodiments merely represent several implementation manners of the present disclosure, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the disclosed patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several modifications and improvements can still be made, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure patent shall be subject to the appended claims.

Claims

1. A USB port control circuit, characterized in that, Including: A step-down output circuit for stepping down the input voltage and outputting it. The controllable end of the step-down output circuit is used to connect to the control end of a single-chip microcomputer so that the single-chip microcomputer records the total current state of the step-down output circuit; A USB output circuit including a plurality of USB output sub-circuits. The plurality of USB output sub-circuits are connected in series and connected to the output end of the step-down output circuit; An overcurrent protection control circuit. The number of the overcurrent protection control circuits is multiple and is equal to the number of the USB output sub-circuits. Each overcurrent protection control circuit is correspondingly connected to the grounding end of each USB output sub-circuit. The overcurrent protection control circuit includes a first control tube, a first resistor, a second resistor and a third resistor. The first end of the first control tube is connected to the grounding end of the USB output sub-circuit. The second end of the first control tube is respectively connected to the first end of the second resistor and the first end of the third resistor. The control end of the first control tube is used to connect to the enabling end of the single-chip microcomputer through the first resistor. The second end of the second resistor is used to connect to the acquisition end of the single-chip microcomputer. The second end of the third resistor is connected to the negative power supply terminal.

2. The USB port control circuit according to claim 1, wherein The overcurrent protection control circuit further includes a fourth resistor. The first end of the fourth resistor is connected to the second end of the first control tube. The second end of the fourth resistor is connected to the control end of the first control tube.

3. The USB port control circuit according to claim 2, characterized in that, The overcurrent protection control circuit further includes a second control tube. The first end of the second control tube is connected to the grounding end of the USB output sub-circuit. The second end of the second control tube is connected to the first end of the fourth resistor. The control end of the second control tube is connected to the second end of the fourth resistor.

4. The USB port control circuit according to claim 1, wherein, The number of the USB output sub-circuits is three, namely a first USB output sub-circuit, a second USB output sub-circuit and a third USB output sub-circuit. Each overcurrent protection control circuit is respectively connected to the grounding ends of the first USB output sub-circuit, the second USB output sub-circuit and the third USB output sub-circuit.

5. The USB port control circuit according to claim 4, wherein The USB port control circuit further includes a first bidirectional zener diode. The upper half end of the first bidirectional zener diode is connected to the power connection end of the first USB output sub-circuit. The lower half end of the first bidirectional zener diode is grounded.

6. The USB port control circuit according to claim 4, wherein The USB port control circuit further includes a second bidirectional zener diode. The upper half end of the second bidirectional zener diode is connected to the power connection end of the second USB output sub-circuit. The lower half end of the second bidirectional zener diode is grounded.

7. The USB port control circuit according to claim 4, wherein, The USB port control circuit further includes a third bidirectional zener diode. The upper half end of the third bidirectional zener diode is connected to the power connection end of the third USB output sub-circuit. The lower half end of the third bidirectional zener diode is grounded.

8. The USB port control circuit according to claim 1, wherein The USB port control circuit further includes a voltage stabilizing capacitor. The upper half end of the voltage stabilizing capacitor is connected to the output end of the step-down output circuit. The lower half end of the voltage stabilizing capacitor is grounded.

9. The USB port control circuit according to claim 8, wherein The USB port control circuit further includes a fourth bidirectional zener diode. The first end of the fourth bidirectional zener diode is connected to the upper half end of the voltage stabilizing capacitor. The second end of the fourth bidirectional zener diode is grounded.

10. A portable energy storage device, characterized in that, Including the USB port control circuit according to any one of claims 1-9.

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