USB power supply overcurrent protection circuit

Abstract

The utility model relates to the technical field of power supply protection circuits, in particular to a USB power supply over-current protection circuit, which is applied to intelligent equipment, comprises a power supply input circuit and a hardware over-current detection control circuit, and adopts a dual over-current protection function of hardware and software. After over-current protection is started, the software over-current control and over-current prompt circuit prompts over-current information to a user, when over-current or short-circuit occurs in a load, self-feedback is performed on the over-current through the hardware over-current detection control circuit, and the hardware over-current detection control circuit immediately cuts off voltage output; and secondly, when data generated by overcurrent or short circuit is fed back to the software overcurrent control and overcurrent prompt circuit, the software overcurrent control and overcurrent prompt circuit further forcibly cuts off voltage output after receiving the overcurrent or short circuit data, and meanwhile, overcurrent information is fed back to a user, so that a prompt effect is achieved for the user. The circuit not only has more flexible circuit characteristics, but also can meet the requirements of different equipment and application scenes.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply protection circuits, in particular to a USB power supply overcurrent protection circuit. Background Art

[0002] Existing USB power supply overcurrent protection circuits typically implement overcurrent protection using integrated chips. This design is relatively mature and stable. However, as smart devices continue to demand more USB functionality, most existing USB overcurrent protection integrated chips have shown limitations in these areas. Therefore, there is an urgent need for a USB overcurrent protection circuit that combines hardware-based overcurrent protection with software-based overcurrent control and overcurrent notification. Utility Model Content

[0003] The utility model aims to solve the defects and shortcomings of the prior art and provides a USB power supply overcurrent protection circuit with a simple structure.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a USB power supply overcurrent protection circuit, which is applied to smart devices. The USB power supply overcurrent protection circuit includes a power input circuit, a hardware overcurrent detection control circuit, an output switch control circuit, a USB power output circuit and a software overcurrent control and overcurrent prompt circuit. The output end of the power input circuit is electrically connected to the input end of the hardware overcurrent detection control circuit and the output switch control circuit, the output end of the hardware overcurrent detection control circuit is electrically connected to the input end of the output switch control circuit, the output end of the output switch control circuit is electrically connected to the input end of the USB power output circuit, and the software overcurrent control and overcurrent prompt circuit is electrically connected to the output switch control circuit and the USB power output circuit.

[0005] Furthermore, the software overcurrent control and overcurrent prompt circuit includes an MCU, a first transistor, a MOS switch tube, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor; one end of the first resistor is connected to a 5V input voltage, and the other end is connected to the USB_CTL pin of the MCU; one end of the second resistor is electrically connected to the first resistor, and the other end is electrically connected to the base of the first transistor; one end of the third resistor is connected to the collector of the first transistor, and the other end is electrically connected to the hardware overcurrent detection control circuit; the emitter of the first transistor is grounded, and the emitter of the MOS switch tube is grounded. The gate is electrically connected to the hardware overcurrent detection control circuit, and the source of the MOS switch tube is electrically connected to the hardware overcurrent detection control circuit; one end of the fourth resistor is electrically connected to the drain of the MOS switch tube, and the other end is grounded; the drain of the MOS switch tube is connected to the USB5V output voltage; the fifth resistor and the sixth resistor are connected in series, one end is grounded, and the other end is connected to the USB_DET pin of the MCU; one end of the seventh resistor is electrically connected to the fourth resistor, and the other end is connected to the common end of the fifth resistor and the sixth resistor; one end of the first capacitor is connected to the fifth resistor, and the other end is electrically connected to the drain of the MOS switch tube.

[0006] Furthermore; the hardware overcurrent detection control circuit includes a second transistor, a second capacitor, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor; one end of the second capacitor is connected to a 5V input voltage, and the other end is grounded; one end of the eighth resistor is electrically connected to the second capacitor, and the other end is electrically connected to the source of the MOS switch tube; the ninth resistor and the tenth resistor are connected in series, one end is connected to the common end of the eighth resistor and the source of the MOS switch tube, and the other end is grounded; the base of the second transistor is connected to the common end of the ninth resistor and the tenth resistor, the collector of the second transistor is connected to the common end of the third resistor and the gate of the MOS switch tube, and the emitter of the second transistor is electrically connected to the eighth resistor; one end of the eleventh resistor is electrically connected to the emitter of the second transistor, and the other end is electrically connected to the collector of the second transistor.

[0007] Furthermore, the type of the second transistor is PNP.

[0008] Furthermore, the type of the first transistor is NPN.

[0009] Furthermore, the MOS switch tube is a P-channel MOS switch tube.

[0010] Beneficial effects of the utility model:

[0011] The utility model provides a USB power supply overcurrent protection circuit, which adopts dual overcurrent protection functions of hardware and software. After the overcurrent protection is activated, the software overcurrent control and overcurrent prompt circuit prompts the user of the overcurrent information. When the load has an overcurrent or short circuit, the overcurrent is first self-feedbacked by the hardware overcurrent detection control circuit, and the hardware overcurrent detection control circuit immediately cuts off the voltage output. Then, when the data generated by the overcurrent or short circuit is fed back to the software overcurrent control and overcurrent prompt circuit, the software overcurrent control and overcurrent prompt circuit further forcibly cuts off the voltage output after receiving the overcurrent or short circuit data, and simultaneously feeds back the overcurrent information to the user to serve as a prompt. The circuit not only has more flexible circuit characteristics, but also can meet the needs of different devices and application scenarios. The present application is not only simple in structure, highly practical, but also low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a block diagram of the working principle of a USB power supply overcurrent protection circuit of the utility model;

[0013] Figure 2 This is a circuit schematic diagram of a USB power supply overcurrent protection circuit of the present utility model. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0015] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0016] In addition, the descriptions of "first," "second," etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0017] The utility model provides a USB power supply overcurrent protection circuit.

[0018] In the embodiment of the present utility model, Figure 1-2 As shown, a USB power supply overcurrent protection circuit is applied to smart devices. The USB power supply overcurrent protection circuit includes a power input circuit, a hardware overcurrent detection control circuit, an output switch control circuit, a USB power output circuit and a software overcurrent control and overcurrent prompt circuit. The output end of the power input circuit is electrically connected to the input end of the hardware overcurrent detection control circuit and the output switch control circuit, the output end of the hardware overcurrent detection control circuit is electrically connected to the input end of the output switch control circuit, the output end of the output switch control circuit is electrically connected to the input end of the USB power output circuit, and the software overcurrent control and overcurrent prompt circuit is electrically connected to the output switch control circuit and the USB power output circuit.

[0019] In this embodiment, the software overcurrent control and overcurrent prompt circuit includes an MCU, a first transistor, a MOS switch tube, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor; one end of the first resistor is connected to a 5V input voltage, and the other end is connected to the USB_CTL pin of the MCU; one end of the second resistor is electrically connected to the first resistor, and the other end is electrically connected to the base of the first transistor; one end of the third resistor is connected to the collector of the first transistor, and the other end is electrically connected to the hardware overcurrent detection control circuit; the emitter of the first transistor is grounded, and the MOS switch tube The gate is electrically connected to the hardware overcurrent detection control circuit, and the source of the MOS switch tube is electrically connected to the hardware overcurrent detection control circuit; one end of the fourth resistor is electrically connected to the drain of the MOS switch tube, and the other end is grounded; the drain of the MOS switch tube is connected to the USB5V output voltage; the fifth resistor and the sixth resistor are connected in series, one end is grounded, and the other end is connected to the USB_DET pin of the MCU; one end of the seventh resistor is electrically connected to the fourth resistor, and the other end is connected to the common end of the fifth resistor and the sixth resistor; one end of the first capacitor is connected to the fifth resistor, and the other end is electrically connected to the drain of the MOS switch tube.

[0020] In this embodiment, the hardware overcurrent detection control circuit includes a second transistor, a second capacitor, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor; one end of the second capacitor is connected to a 5V input voltage, and the other end is grounded; one end of the eighth resistor is electrically connected to the second capacitor, and the other end is electrically connected to the source of the MOS switch tube; the ninth resistor and the tenth resistor are connected in series, one end is connected to the common end of the eighth resistor and the source of the MOS switch tube, and the other end is grounded; the base of the second transistor is connected to the common end of the ninth resistor and the tenth resistor, the collector of the second transistor is connected to the common end of the third resistor and the gate of the MOS switch tube, and the emitter of the second transistor is electrically connected to the eighth resistor; one end of the eleventh resistor is electrically connected to the emitter of the second transistor, and the other end is electrically connected to the collector of the second transistor.

[0021] In this embodiment, the type of the second transistor is PNP.

[0022] In this embodiment, the type of the first transistor is NPN.

[0023] In this embodiment, the MOS switch tube is a P-channel MOS switch tube.

[0024] Specifically, the working principle of the USB power supply overcurrent protection circuit in this application is as follows:

[0025] When the power supply is in the normal output state, the MCU's GP_IO is used to control the on and off of USB5V. After power is turned on, the MCU's USB_CTL pin defaults to a high level state, and the first transistor Q10 is in a saturated conduction state. At this time, the gate voltage of the MOS switch tube Q11 is pulled low, thereby turning on the MOS switch tube Q11. The +5V current flows to the high-power eighth resistor R134 and outputs USB5V through the MOS switch tube Q11.

[0026] When the load current at the USB5V output voltage output end exceeds the design value, where the load current exceeds the design value and is set according to actual use; a voltage difference will be generated across the high-power eighth resistor R134. When the voltage difference reaches the set value, the second transistor Q8 will be triggered to saturate and conduct; that is, when the voltage between the base b and the emitter e of the second transistor Q8 is greater than 0.7 volts, the second transistor Q8 will be triggered to saturate and conduct. When the second transistor Q8 is saturated and conducted, its collector C outputs a high voltage to the gate of the MOS switch tube Q11, thereby causing the MOS switch tube Q11 to enter the cut-off state, and plays a hardware overcurrent protection role when the USB5V output voltage is 0 volts.

[0027] When the USB5V output voltage is 0V, the MCU detects that the USB_DET pin is at a low level. The MCU will immediately change the output of the USB_CTL pin from a high level to a low level. The first transistor Q10 changes from a saturated conduction state to a cut-off state. At this time, the gate voltage of the MOS switch tube increases, ensuring that the MOS switch tube Q11 is cut off, thereby playing a role of soft overcurrent protection.

[0028] When the USB_DET pin of the MCU detects a low level, the MCU can display USB overcurrent through the system and convey overcurrent information to the user as a reminder. The USB 5V output voltage can only be output normally after the overcurrent is eliminated.

[0029] It should be noted that in the present application, the design of the load overcurrent point is mainly achieved by adjusting the eighth resistor R134, the ninth resistor R135 and the tenth resistor R137.

[0030] This design addresses the shortcomings of existing USB overcurrent protection circuits by adopting a novel approach. This application utilizes discrete components to construct a USB overcurrent protection circuit. These discrete components include a first resistor, a first transistor, a second transistor, and a MOS switch. By combining these components to create an overcurrent protection circuit, the circuit design becomes more flexible, allowing the overcurrent protection point to be customized based on actual needs. When the load experiences an overcurrent or short circuit, the circuit provides dual overcurrent protection. First, the hardware overcurrent detection control circuit provides self-feedback on the overcurrent, immediately shutting off the voltage output. Second, the overcurrent or short circuit data is fed back to the MCU, which then forcibly shuts off the voltage output and provides overcurrent information to the user as a user-friendly reminder. This circuit not only offers more flexible circuit characteristics but also meets the needs of diverse devices and application scenarios.

[0031] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the utility model concept, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A USB power supply overcurrent protection circuit, characterized in that: Applied to smart devices, the USB power supply overcurrent protection circuit includes a power input circuit, a hardware overcurrent detection control circuit, an output switch control circuit, a USB power output circuit, and a software overcurrent control and overcurrent prompt circuit. The output end of the power input circuit is electrically connected to the input ends of the hardware overcurrent detection control circuit and the output switch control circuit, the output end of the hardware overcurrent detection control circuit is electrically connected to the input end of the output switch control circuit, the output end of the output switch control circuit is electrically connected to the input end of the USB power output circuit, and the software overcurrent control and overcurrent prompt circuit is electrically connected to the output switch control circuit and the USB power output circuit. The software overcurrent control and overcurrent prompt circuit includes an MCU, a first transistor, a MOS switch tube, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first capacitor; one end of the first resistor is connected to a 5V input voltage, and the other end is connected to the USB_CTL pin of the MCU; one end of the second resistor is electrically connected to the first resistor, and the other end is electrically connected to the base of the first transistor; one end of the third resistor is connected to the collector of the first transistor, and the other end is electrically connected to the hardware overcurrent detection control circuit; the emitter of the first transistor is grounded, and the gate of the MOS switch tube is grounded. The fourth resistor is electrically connected to the hardware overcurrent detection control circuit, and the source of the MOS switch tube is electrically connected to the hardware overcurrent detection control circuit; one end of the fourth resistor is electrically connected to the drain of the MOS switch tube, and the other end is grounded; the drain of the MOS switch tube is connected to the USB5V output voltage; the fifth resistor and the sixth resistor are connected in series, one end is grounded, and the other end is connected to the USB_DET pin of the MCU; one end of the seventh resistor is electrically connected to the fourth resistor, and the other end is connected to the common end of the fifth resistor and the sixth resistor; one end of the first capacitor is connected to the fifth resistor, and the other end is electrically connected to the drain of the MOS switch tube.

2. The USB power supply overcurrent protection circuit according to claim 1, wherein: The hardware overcurrent detection control circuit includes a second transistor, a second capacitor, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor; one end of the second capacitor is connected to a 5V input voltage, and the other end is grounded; one end of the eighth resistor is electrically connected to the second capacitor, and the other end is electrically connected to the source of the MOS switch tube; the ninth resistor and the tenth resistor are connected in series, one end is connected to the common end of the eighth resistor and the source of the MOS switch tube, and the other end is grounded; the base of the second transistor is connected to the common end of the ninth resistor and the tenth resistor, the collector of the second transistor is connected to the common end of the third resistor and the gate of the MOS switch tube, and the emitter of the second transistor is electrically connected to the eighth resistor; one end of the eleventh resistor is electrically connected to the emitter of the second transistor, and the other end is electrically connected to the collector of the second transistor.

3. The USB power supply overcurrent protection circuit according to claim 2, wherein: The type of the second transistor is PNP.

4. The USB power supply overcurrent protection circuit according to claim 1, wherein: The type of the first transistor is NPN.

5. The USB power supply overcurrent protection circuit according to claim 2, wherein: The MOS switch tube is a P-channel MOS switch tube.

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