Protection circuit for a power-limited power supply and power supply device

Abstract

The application discloses a protection circuit of a limited power supply, and belongs to the field of power supplies. The protection circuit comprises a protocol control module, an under-voltage protection module, a limited power supply and a feedback module which are connected respectively, and is used for outputting a first feedback signal to the feedback module and outputting an enable signal to the under-voltage protection module when detecting that an output port of the limited power supply exists overload; the under-voltage protection module is driven to work by the enable signal and outputs a second feedback signal to the feedback module in a working state; the feedback module is connected with the protocol control module, the under-voltage protection module and a PWM control module respectively, and is used for carrying out isolation processing on the first feedback signal and the second feedback signal and providing the PWM control module; the PWM control module is connected with the feedback module and the limited power supply respectively, and is used for controlling the output voltage of the output port of the limited power supply to decrease to a preset voltage threshold according to the first feedback signal or according to the first feedback signal and the second feedback signal.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power supply, and particularly relates to a protection circuit of a limited power supply and a power supply device. BACKGROUND

[0002] The fireproof grade of the shell of an electronic equipment product needs to be V0 and above, and in the case that the power supply device of the electronic equipment is a limited power supply (LPS), the electronic equipment can use a shell of HB grade which is cheaper and more environmentally friendly. However, with the development of fast charging protocols with a wide output voltage range and the increase of charging power, it is increasingly difficult for the power supply device to meet the LPS requirement.

[0003] In the implementation of fast charging with a wide output voltage range for a limited power supply, overload protection for the limited power supply is a problem to be solved at present. SUMMARY

[0004] The purpose of the embodiments of the application is to provide a protection circuit of a limited power supply and a power supply device, which can perform overload protection for the limited power supply.

[0005] In a first aspect, the embodiments of the application provide a protection circuit of a limited power supply, comprising an under-voltage protection module, a protocol control module, a feedback module and a pulse width modulation (PWM) control module,

[0006] The protocol control module is connected with the under-voltage protection module, the limited power supply and the feedback module respectively, and is configured to output a first feedback signal to the feedback module and output an enable signal to the under-voltage protection module when detecting that the output port of the limited power supply exists overload;

[0007] The under-voltage protection module is connected with the protocol control module, the limited power supply and the feedback module respectively, and is driven to work by the enable signal and output a second feedback signal to the feedback module in the working state;

[0008] The feedback module is connected with the protocol control module, the under-voltage protection module and the PWM control module respectively, and is configured to isolate and process the first feedback signal and the second feedback signal and provide them to the PWM control module;

[0009] The PWM control module is connected with the feedback module and the limited power supply, and is configured to control the output voltage of the output port of the limited power supply to decrease to a preset voltage threshold according to the first feedback signal or according to the first feedback signal and the second feedback signal.

[0010] In a second aspect, the embodiments of the application provide a power supply device comprising the protection circuit of the first aspect.

[0011] In the embodiment of the present application, when there is an overload at the output port of the limited power supply, the feedback signal provided by the undervoltage protection module is used to control the output voltage of the output port of the limited power supply to decrease to a preset voltage threshold, so as to trigger the undervoltage protection function of the PWM control module. The limited power supply can be effectively protected when the limited power supply performs fast charging in a wide output voltage range. Therefore, the limited power supply with the protection circuit can be applied to electronic devices with a shell of HB level made of cheaper and more environmentally friendly materials, thereby expanding the application range of the limited power supply. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a structure block diagram of the protection circuit of the limited power supply in the embodiment of the present application.

[0013] Figure 2 is a specific example structure block diagram of the protection circuit of the limited power supply in the embodiment of the present application.

[0014] Figure 3 is a circuit schematic diagram of the protection circuit of the limited power supply in the embodiment of the present application. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0016] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are usually a category and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the objects before and after are in a "or" relationship.

[0017] In the embodiments of the present application, a protection circuit of a limited power supply is provided, which includes an undervoltage protection module, a protocol control module, a feedback module, and a pulse width modulation (PWM) control module,

[0018] The protocol control module is connected with the undervoltage protection module, the power-limited power supply and the feedback module respectively, and is configured to output a first feedback signal to the feedback module and output an enable signal to the undervoltage protection module when detecting that the output port of the power-limited power supply is overloaded.

[0019] The undervoltage protection module is connected with the protocol control module, the power-limited power supply and the feedback module respectively, and is driven to work by the enable signal and output a second feedback signal to the feedback module in the working state.

[0020] The feedback module is connected with the protocol control module, the undervoltage protection module and the PWM control module respectively, and is configured to isolate and process the first feedback signal and the second feedback signal and provide the first feedback signal and the second feedback signal to the PWM control module.

[0021] The PWM control module is connected with the feedback module and the power-limited power supply, and is configured to control the output voltage of the output port of the power-limited power supply to decrease to a preset voltage threshold according to the first feedback signal or according to the first feedback signal and the second feedback signal.

[0022] The protection circuit of the power-limited power supply provided by the embodiments of the present application will be described in detail below in combination with the accompanying drawings, specific embodiments and application scenarios.

[0023] Figure 1 is one of the structure block diagrams of the protection circuit of the power-limited power supply of the embodiments of the present application, as Figure 1 shown, the protection circuit 100 of the power-limited power supply (LPS) includes a pulse width modulation (PWM) control module 104, a feedback module 105, a protocol control module 203 and an undervoltage protection module 205.

[0024] One end of the protocol control module 203 is connected with the undervoltage protection module 205, the other end is connected with the output port (not shown in the figure) of the LSP power supply 200, and the third end is connected with the feedback module 105. Figure 1

[0025] The protocol control module 203 is configured to detect whether the output port of the LSP power supply 200 is currently overloaded, and output an enable signal to the undervoltage protection module 205 to drive the undervoltage protection module 205 to start working when detecting that the output port of the LSP power supply 200 is overloaded.

[0026] For example, the enable signal pin of the protocol control module 203 is high when enabled, and is in a high-impedance low state in other states.

[0027] ​The protocol control module 203 can also output a first feedback signal to the feedback module 105. The protocol control module 203 can output the first feedback signal when detecting that the output port of the LSP power supply 200 does not have an overload or when detecting that the output port of the LSP power supply 200 has an overload. Alternatively, the protocol control module 203 can output the first feedback signal only when detecting that the output port of the LSP power supply 200 does not have an overload, and stop outputting the first feedback signal when detecting that the output port of the LSP power supply 200 has an overload.

[0028] The first feedback signal is a current signal used to adjust the output voltage of the output port of the LSP power supply 200. When the protocol control module 203 detects that the output port of the LSP power supply 200 does not have an overload, the feedback current value output by the protocol control module 203 is in the normal microampere level. The protocol control module 203 can output the first feedback signal used to control the LSP power supply 200 to increase or decrease the output voltage of the output port of the LSP power supply 200 according to the actual situation.

[0029] When the protocol control module 203 detects that the output port of the LSP power supply 200 has an overload, the feedback current value output by the protocol control module 203 is in the milliampere level. The greater the feedback current, the faster the output voltage of the output port of the LSP power supply 200 can be controlled to change. In the embodiment of the present application, the output voltage of the output port of the LSP power supply 200 is controlled to decrease to a preset voltage threshold value by the feedback signal to trigger the undervoltage protection function of the PWM control module 104 to protect the LSP power supply 200. Therefore, the first feedback signal output by the protocol control module 203 is used to control the LSP power supply 200 to decrease the output voltage of the output port of the LSP power supply 200.

[0030] Optionally, the overload of the output port includes that the output current of the output port exceeds a preset current threshold value, or when the output current of the output port is close to 0, the working frequency of the PWM control module exceeds a preset frequency threshold value.

[0031] The output voltage of the output port of the LSP power supply 200 can be directly detected by the protocol control module 203 through a detection resistor connected in series to the output port of the LSP power supply 200. The output current of the output port of the LSP power supply 200 can be obtained by the protocol control module 203 through corresponding conversion. When the output current exceeds a preset current threshold value, the current is too large, and the protocol control module 203 detects that the LSP power supply 200 has an output overload.

[0032] When a single point failure occurs in the LSP power supply 200, the protocol control module 203 cannot directly detect the output current from the output port of the LSP power supply 200. The working frequency of the PWM control module 104 can be combined to detect the output current of the output port of the LSP power supply 200.

[0033] The frequency is used to determine the operating frequency. The PWM control module 104 controls the switching of the power switching transistors in the LSP power supply 200. The operating frequency of the PWM control module 104 is output to the LSP power supply 200. Therefore, the protocol control module 203 can detect the operating frequency of the PWM control module 104 from the output rectifier module connected to the output port of the LSP power supply 200. If the operating frequency of the PWM control module exceeds the preset frequency threshold, and the operating frequency is too high, the protocol control module 203 detects that the LSP power supply 200 has an output overload.

[0034] One end of the undervoltage protection module 205 is connected to the protocol control module 203, the other end is connected to the output port of the LSP power supply 0 200, and the third end is connected to the feedback module 105.

[0035] As described above, when the protocol control module 203 detects an output overload at the output port of the LSP power supply 200, it outputs an enable signal to the undervoltage protection module 205 to drive the undervoltage protection module 205 to start working. The undervoltage protection module 205 is used to control and limit the output of the power supply by outputting a feedback signal.

[0036] When the output voltage of the port drops to a preset voltage threshold, the undervoltage protection function of the PWM control module 104 is triggered to protect the LSP power supply 200.

[0037] The PWM control module 104 itself has overvoltage protection and undervoltage protection functions. Specifically, if the PWM control module 104 is operating normally, the output voltage at its output port must be between the set upper and lower voltage limits. If the voltage exceeds the set upper limit, the overvoltage protection point of the PWM control module 104 will be triggered, thus activating its overvoltage protection function. If the voltage exceeds the set lower limit, the undervoltage protection point of the PWM control module 104 will be triggered, thus activating its undervoltage protection function. Regardless of whether the overvoltage or undervoltage protection function is triggered, the PWM control module 104 will restart at a certain frequency, thereby protecting the LSP power supply 200.

[0038] When a power-limited power supply is charging within a wide output voltage range using a fast charging protocol, a linear voltage regulator circuit is typically added to the power supply voltage line of the PWM control module to limit the maximum value of the power supply voltage of the PWM control module, ensuring that the PWM control module operates normally throughout the entire output voltage range of the power-limited power supply.

[0039] However, under the influence of the linear voltage stabilizing circuit, the output voltage of the output port of the power-limited power supply and the supply voltage of the PWM control module do not present a linear relationship, so that the increase of the output voltage cannot correspond to the linear increase of the supply voltage of the PWM control module, so as to reach the overvoltage protection point of the PWM control module and trigger the overvoltage protection function of the PWM control module.

[0040] In the embodiment of the application, the under-voltage protection module 205 outputs a second feedback signal to the feedback module 105 in the working state, triggers the under-voltage protection function of the PWM control module 104, and realizes the protection of the LSP power supply 200, which will be described in detail below.

[0041] One end of the feedback module 105 is connected with the protocol control module 203 and the under-voltage protection module 205 respectively, for receiving the first feedback signal output by the protocol control module 203 and receiving the second feedback signal output by the under-voltage protection module 205, and the other end of the feedback module 105 is connected with the PWM control module 104.

[0042] The feedback module 105 is used for isolating the received first feedback signal or the received first feedback signal and the second feedback signal, and providing to the PWM control module 104. The feedback module 105 is an optical coupling element, and is connected across the primary and secondary of the transformer of the LSP power supply 200, so that the first feedback signal and the second feedback signal can be isolated by optical coupling, and then provided to the PWM control module 104 to meet the isolation requirement of the primary and secondary of the transformer of the LSP power supply 200.

[0043] 5One end of the PWM control module 104 is connected with the feedback module 105, and the other end is connected with the LSP power supply 200, for adjusting the output voltage of the output port of the LSP power supply 200 according to the first feedback signal received by the feedback module 105 or according to the first feedback signal and the second feedback signal received by the feedback module 105. The PWM control module 104 adjusts the output voltage of the output port of the LSP power supply 200 according to the feedback signal

[0044] The output voltage of the output port of the LSP power supply 200 adjusted by the PWM control module 104 includes two cases that the output port of the LSP power supply 200 does not exist overload and exists overload.

[0045] In one embodiment, optionally, when the output port does not exist overload, the first feedback signal is used to control the output voltage of the output port 202 to increase or decrease; when the output port 202 exists overload, the first feedback signal is used to control the output voltage of the output port 202 to decrease.

[0046] Correspondingly, the PWM control module 104 controls the output voltage of the output port 202 to decrease according to the first feedback signal and the second feedback signal when the output voltage of the output port 202 decreases to a first preset threshold voltage.

[0047] The output voltage of the output port 202 decreases; and the PWM control module 104 controls the output voltage of the output port 202 to decrease according to the second feedback signal when the output voltage of the output port 202 decreases to a second preset threshold voltage.

[0048] The first preset threshold voltage does not trigger the undervoltage protection function of the protocol control module, and the second preset threshold voltage triggers the undervoltage protection function of the protocol control module.

[0049] In the above embodiment, when there is no overload in the output port of the LSP power supply 200, the undervoltage protection module 205 is not driven to work, and thus the PWM control module 104 only receives the first feedback signal output by the protocol control module 203 through the feedback module 105. At this time, the PWM control module 104 can control the output voltage of the output port of the LSP power supply 200 to increase or decrease according to the corresponding received first feedback signal.

[0050] When there is an overload in the output port of the LSP power supply 200, the undervoltage protection module 205 is driven to work, and thus the PWM control module 104 receives the first feedback signal output by the protocol control module 203 and the second feedback signal output by the undervoltage protection module 205. At this time, the PWM control module 104 can control the output voltage of the output port of the LSP power supply 200 to decrease according to the corresponding received first feedback signal and second feedback signal through the feedback module 105.

[0051] Since the protocol control module 203 also has an undervoltage protection function and an overvoltage protection function, and the output voltage of the output port triggering the undervoltage protection function of the protocol control module 203 is higher than the output voltage of the output port triggering the undervoltage protection function of the PWM control module 104. Therefore, in the process of the PWM control module 104 controlling the output voltage of the output port of the LSP power supply 200 to gradually decrease according to the first feedback signal and the second feedback signal, the undervoltage protection function of the protocol control module 203 is triggered first, and thus the protocol control module 203 stops working and no longer outputs the first feedback signal to the PWM control module 104 through the feedback module 105.

[0052] At this time, the second feedback signal outputted by the under-voltage protection module 205 can be directly outputted to the feedback module 105 and provided to the PWM control module 104, and the output voltage of the output port of the LSP power supply 200 is gradually reduced by the PWM control module 104 until the threshold voltage triggering the under-voltage protection function of the PWM control module 104 is reached. Thus, the LSP power supply 200 is protected when the overload exists in the output port of the LSP power supply 200.

[0053] In another embodiment, the first feedback signal is used to control the output voltage of the output port 202 to increase or decrease when the overload does not exist in the output port 202, and the second feedback signal is used to control the output voltage of the output port 202 to decrease when the overload exists in the output port 202.

[0054] The protocol control module 203 outputs an enable signal to the under-voltage protection module 205 and stops outputting the first feedback signal to the feedback module 105 when detecting that the overload exists in the output port 202.

[0055] Correspondingly, the PWM control module 104 controls the output voltage of the output port 202 to decrease according to the second feedback signal until the threshold voltage triggering the under-voltage protection function of the protocol control module 203 is reached.

[0056] In this embodiment, the protocol control module 203 only outputs the feedback signal when the overload does not exist in the output port of the LSP power supply 200, and stops outputting the feedback signal when the overload exists in the output port of the LSP power supply 200.

[0057] Similarly, when the overload does not exist in the output port of the LSP power supply 200, the under-voltage protection module 205 is not driven to work, and the PWM control module 104 only receives the first feedback signal outputted by the protocol control module 203 through the feedback module 105. At this time, the PWM control module 104 can control the output voltage of the output port of the LSP power supply 200 to increase or decrease according to the corresponding received first feedback signal.

[0058] When the overload exists in the output port of the LSP power supply 200, the under-voltage protection module 205 is driven to work, and the protocol control module 203 stops outputting the feedback signal. Therefore, the PWM control module 104 only receives the second feedback signal outputted by the under-voltage protection module 205 through the feedback module 105. At this time, the PWM control module 104 can control the output voltage of the output port of the LSP power supply 200 to decrease according to the corresponding received second feedback signal, so as to trigger the under-voltage protection function of the PWM control module 104. Thus, the LSP power supply 200 is protected when the overload exists in the output port of the LSP power supply 200.

[0059] In the following, the embodiments of the application will be described in detail with reference to the accompanying drawings. Figure 2The circuit structure of a protection circuit of a limited power supply is described.

[0060] Optionally, the under-voltage protection module comprises an energy storage unit 2052, a self-locking unit 2054 and a current source unit 2056. The energy storage unit 2052 is connected with the limited power supply 200 and the self-locking unit 2054. The self-locking unit 2054 has a first end connected with the energy storage unit 2052, a second end connected with the protocol control module 203, and a third end connected with the current source unit 2056. The enable signal output by the protocol control module 203 drives the self-locking unit 2054 to work, and the energy storage unit 2052 stores the electric quantity in the working state to drive the current source unit 2056 to work. The current source unit 2056 has a first end connected with the third end of the self-locking unit 2054, and a second end connected with the feedback module 105, for providing the second feedback signal to the feedback module 105 in the working state.

[0061] Reference is now made to Figure 2 The under-voltage protection module 205 comprises an energy storage unit 2052, a self-locking unit 2054 and a current source unit 2056. The LSP power supply 200 comprises an input port 101, an input rectification filter 102, a power transmission module 103, an output rectification module 201 and an output port 202.

[0062] One end of the energy storage unit 2052 is connected with the output port 202 of the LSP power supply 200, and the other end is connected with the self-locking unit 2054, for storing the electric quantity through the current output by the output port 202. One end of the self-locking unit 2054 is connected with the energy storage unit 2052, and the other end is connected with one end of the protocol control module 203, for receiving the enable signal output by the protocol control module 203 and being driven to work. The third end of the self-locking unit 2054 is connected with the current source unit 2056, and continuously drives the current source unit 2056 to work through the stored electric quantity of the energy storage unit 2052 in the working state. One end of the current source unit 2056 is connected with the self-locking unit 2054, and the other end is connected with the input end of the feedback module 105, for providing the second feedback signal to the feedback module 105 in the working state.

[0063] Optionally, the energy storage unit 2052 comprises a diode D1 and a first capacitor C1. The first end of the first capacitor C1 is connected with the first end of the diode D1, the second end is connected with the first end of a load circuit Cout of the limited power supply and grounded, and the second end of the load circuit Cout is connected with the output port 202 of the limited power supply. The second end of the diode D1 is connected with the output port 202.

[0064] As Figure 3As shown, the energy storage unit 2052 includes a diode D1 and a first capacitor C1. One end of the first capacitor C1 is connected to one end of the diode D1, and the other end of the first capacitor C1 is connected to one end of the load circuit Cout connected to the power limiting power output port 202 and grounded. The power limiting power output port is used to provide charging current to the load circuit Cout. The other end of the diode D1 is connected to the output port 202. That is, the diode D1 and the first capacitor C1 are connected in series and together with the load circuit Cout in parallel at the power limiting power output port 202.

[0065] If there is an overload at the power supply output port, the load circuit Cout needs to draw current from other feasible paths. This is achieved by connecting a diode D1 in series with the first capacitor C1, which is connected in parallel with the load circuit Cout. This prevents the energy stored in the first capacitor C1 from being released through the load circuit Cout when there is an overload at the power supply output port.

[0066] Optionally, the self-locking unit 2054 includes a first transistor, a second transistor, and a second capacitor C2. The base of the first transistor is connected to the first terminal of the protocol control module 203 to receive the enable signal, the emitter is connected to the second capacitor C2, and the collector is connected to the second transistor. The base of the second transistor is connected to the collector of the first transistor, and the collector is connected to the base of the first transistor. The emitter is connected to the first capacitor C1. The first terminal of the second capacitor C2 is connected to the emitter of the first transistor, and the second terminal is grounded.

[0067] like Figure 3 As shown, the self-locking unit 2054 includes two transistors Q 11 and Q 12 The self-locking transistor Q1 and the second capacitor C2 are configured. 11 The base of transistor Q is connected to the first terminal of protocol control module 203 via port H1 to receive the enable signal sent by protocol control module 203. 11 The emitter of transistor Q is connected to the second capacitor C2 to provide current to the second capacitor C2 for energy storage. 11 collector and transistor Q 12 The base connection of the transistor Q 12 collector and diode Q 11 The base connection of the transistor Q 12 The emitter of the transistor is connected to one end of diode D1 and the first capacitor C1, respectively. One end of the second capacitor C2 is connected to transistor Q. 12 The emitter of the first capacitor is connected, and the other end of the second capacitor C2 is grounded.

[0068] The self-locking triode Q1 is turned on after receiving the enable signal of the protocol control module 203, and the self-locking triode Q1 can still maintain the turned-on state by itself after the enable signal disappears.

[0069] Optionally, the self-locking unit 2054 further comprises a first resistor R1 and a second resistor R2, the first resistor R1 has a first end connected with a second end of the second capacitor C2 and a second end connected with a first end of the protocol control module 203; and the second resistor R2 is arranged between an emitter of the second triode and a first end of the first capacitor C1.

[0070] As shown in Figure 3 , the self-locking unit 2054 comprises the first resistor R1 and the second resistor R2, one end of the first resistor R1 is connected with one end of the second capacitor C2 grounded, and the other end of the first resistor R1 is connected with a first end of the protocol control module 203 through the port H1. That is, the first resistor R1 is connected with the second capacitor C2 in parallel, so as to adjust the current passing through the second capacitor C2, and play a role of current limiting and protection for the second capacitor C2.

[0071] The second resistor R2 is arranged between the emitter of the triode Q 12 and one end of the diode D1 and the first capacitor C1, for adjusting the current that can turn on the self-locking triode Q1 when the storage electric quantity of the first capacitor C1 is released, and playing a role of current limiting and turning on for the self-locking triode Q1.

[0072] Optionally, the current source unit 2056 comprises a third triode Q2 and a third resistor R3, a base of the third triode Q2 is connected with a first end of the second capacitor C2, a collector of the third triode Q2 is connected with the third resistor, and an emitter of the third triode Q2 is connected with a first end of the feedback module 105 to output the second feedback signal to the feedback module 105 in the turned-on state; and the third resistor is arranged between the collector of the third triode Q2 and the first end of the first capacitor C1.

[0073] As shown in Figure 3 , the current source unit 2056 comprises the third triode Q2 and the third resistor R3, the base of the third triode Q2 is connected with one end of the second capacitor C2 and the emitter of the triode Q 11 , the collector of the third triode Q2 is connected with the third resistor R3, and the emitter is connected with the first end of the feedback module 105 through the port H2, so as to output the second feedback signal to the feedback module 105 in the turned-on state.

[0074] The third triode Q2 is a common triode, and can provide a second feedback signal for the feedback module 105 after being turned on. The third resistor R3 is arranged between the collector of the third triode Q2 and the first end of the first capacitor C1, and is used to adjust the current for turning on the third triode Q2 when the storage capacity of the second capacitor C2 is released, so as to limit the current and turn on the third triode Q2.

[0075] The working principle of the protection circuit of the limited power supply is described as follows in combination with the above-described drawings.

[0076] During the starting process of the limited power supply, the voltage of the output port 202 of the limited power supply gradually rises and synchronously charges the energy storage unit 2052, and the enable signal of the protocol control module 203 is at a low level, so that the self-locking unit 2054 and the current source unit 2056 do not work.

[0077] When the limited power supply enters normal working, the enable signal of the protocol control module 203 is still at a low level, so that the self-locking unit 2054 and the current source unit 2056 do not work, and the limited power supply works normally.

[0078] When the limited power supply is powered on and works normally, the enable signal is at a low level, so that the undervoltage protection module 205 does not work, and the output voltage of the output port of the limited power supply charges the first capacitor C1 in the energy storage unit 2052 of the undervoltage protection module 205 to store energy.

[0079] When the protocol control module 203 detects that the output port 202 of the limited power supply is overloaded, the enable signal is changed to a high level, and the self-locking unit 2054 and the current source unit 2056 start to work to provide a feedback signal for the feedback module 105, and the PWM control module 104 gradually reduces the output voltage of the output port 202 of the limited power supply.

[0080] Taking the case that the protocol control module 203 provides a feedback signal for reducing the output voltage to the feedback module 105 when detecting that the output port 202 of the limited power supply is overloaded as an example, the specific process is as follows:

[0081] When the protocol control module 203 detects that the output port 202 of the limited power supply is overloaded, the first feedback signal provided for the feedback module 105 is increased, and the enable signal of the protocol control module 203 is changed to a high level. Under the action of the enable signal, the self-locking unit 2052 starts to work, the self-locking triode Q1 of the self-locking unit 2052 changes from a closed state to a conducting state, the first capacitor C1 of the energy storage unit 2052 charges the second capacitor C2 through the self-locking triode Q1, and then the triode Q2 of the current source unit 2056 is turned on, and the first capacitor C1 provides an additional second feedback signal for the feedback module 105 through the third triode Q2.

[0082] The PWM control module 104 sends a switching pulse signal to the power switch tube in the power transmission module 103 of the limited power supply 200 according to the first feedback signal and the second feedback signal, directly affects the reduction of energy transmission of the transformer in the power transmission module 103 by adjusting the turn-on and turn-off time of the power switch tube according to the feedback signal, that is, by reducing the duty cycle, thereby continuously reducing the energy transmitted to the output port 202 of the limited power supply 200. Under the action of the overloaded load circuit Cout, the output voltage of the output port 202 rapidly decreases, and when the output voltage of the output port 202 decreases to the under-voltage protection point of the protocol control module 203, the protocol control module 203 stops working and releases the control of the feedback module 105, and at the same time, the enable signal turns to low level.

[0083] After the enable signal turns to low level, because the self-locking transistor Q1 in the self-locking unit 2054 has a self-locking function, the self-locking transistor Q1 remains in the conduction state after the enable signal disappears, provides a driving signal for the conduction of the third transistor Q2, and makes the third transistor Q2 remain in the conduction state. The energy of the first capacitor C1 in the energy storage unit 2052 continues to provide the second feedback signal for the feedback module 105 through the third transistor Q2, so as to further reduce the output voltage of the output port 202, until triggering the under-voltage protection function of the PWM control module 104.

[0084] After the PWM control module 104 triggers the under-voltage protection, the limited power supply is restarted at a certain frequency, and if the overload still exists in the output port 202 of the limited power supply after the limited power supply is restarted, the above steps are repeated, and the under-voltage protection function of the PWM control module 104 is triggered again, so as to realize the protection of the limited power supply.

[0085] In the embodiment of the present application, when the overload exists in the output port of the limited power supply, the under-voltage protection function of the PWM control module is triggered by providing a feedback signal to control the output voltage of the output port of the limited power supply to decrease to a preset voltage threshold, so as to effectively protect the limited power supply when the limited power supply performs wide output voltage range fast charging, and thus the limited power supply with the protection circuit can be applied to electronic devices using a cheaper and more environmentally friendly material HB level shell, thereby expanding the application range of the limited power supply.

[0086] Optionally, the embodiment of the present application also provides a power supply device comprising the protection circuit of the limited power supply of any of the above embodiments.

[0087] It should be noted that, in the present document, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element. Furthermore, it is to be understood that the method and apparatus of the present application can be carried out by more than one process, method, article, or apparatus either simultaneously, concurrently, or with intervening action that are carried out at the same time, either in a simultaneous fashion or in a fashion that is interleaved in time. For example, the described methods can be performed in a different order from that described, and / or various steps can be combined or omitted, and / or additional steps can be added, without departing from the scope of the present application. Also, features described with respect to certain examples can be combined in other examples.

[0088] From the above description of the embodiments, it is apparent that the method of the above-described embodiments can be realized by software plus necessary universal hardware platform, of course, can also be realized by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of computer software product in essence or in the form of contribution to the prior art, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a plurality of instructions for making a terminal (which can be a mobile phone, computer, server, or network equipment, etc.) execute the method described in each embodiment of the present application.

[0089] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative, but not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the protection scope of the claims, which all belong to the protection scope of the present application.

Claims

1. A protection circuit for a power-limiting power supply, characterized in that, It includes an undervoltage protection module, a protocol control module, a feedback module, and a pulse width modulation control module. The protocol control module is connected to the undervoltage protection module, the power limiting power supply, and the feedback module respectively, and is used to output a first feedback signal to the feedback module and to output an enable signal to the undervoltage protection module when an overload is detected at the output port of the power limiting power supply. The undervoltage protection module is connected to the protocol control module, the power limiting power supply, and the feedback module respectively. It is driven to work by the enable signal and outputs a second feedback signal to the feedback module in the working state. The feedback module is connected to the protocol control module, the undervoltage protection module, and the pulse width modulation control module respectively, and is used to isolate the first feedback signal and the second feedback signal and provide them to the pulse width modulation control module. The pulse width modulation control module is connected to the feedback module and the power limiting power supply respectively, and is used to control the output voltage of the output port of the power limiting power supply to decrease to a preset voltage threshold according to the first feedback signal or according to the first feedback signal and the second feedback signal. The preset voltage threshold is used to trigger the undervoltage protection function of the pulse width modulation control module.

2. The protection circuit according to claim 1, characterized in that, The undervoltage protection module includes an energy storage unit, a self-locking unit, and a current source unit. The energy storage unit is connected to the power-limiting power supply and the self-locking unit; The self-locking unit has a first end connected to the energy storage unit, a second end connected to the protocol control module, and a third end connected to the current source unit. It is driven to work by the enable signal output by the protocol control module, and in the working state, it drives the current source unit to work by the stored power of the energy storage unit. The current source unit has a first end connected to the third end of the self-locking unit and a second end connected to the feedback module, and is used to provide the second feedback signal to the feedback module in the working state.

3. The protection circuit according to claim 2, characterized in that, The energy storage unit includes a diode and a first capacitor. The first capacitor has its first end connected to the first end of the diode, and its second end connected to the first end of the load circuit of the power-limiting power supply and grounded. The second end of the load circuit is connected to the output port of the power-limiting power supply. The second end of the diode is connected to the output port.

4. The protection circuit according to claim 3, characterized in that, The self-locking unit includes a first transistor, a second transistor, and a second capacitor. The base of the first transistor is connected to the first terminal of the protocol control module to receive the enable signal, the emitter is connected to the second capacitor, and the collector is connected to the second transistor. The second transistor has its base connected to the collector of the first transistor, its collector connected to the base of the first transistor, and its emitter connected to the first capacitor. The second capacitor has its first end connected to the emitter of the first transistor and its second end grounded.

5. The protection circuit according to claim 4, characterized in that, The self-locking unit also includes a first resistor and a second resistor. The first resistor has its first end connected to the second end of the second capacitor, and its second end connected to the first end of the protocol control module. The second resistor is disposed between the emitter of the second transistor and the first terminal of the first capacitor.

6. The protection circuit according to claim 4, characterized in that, The current source unit includes a third transistor and a third resistor. The base of the third transistor is connected to the first terminal of the second capacitor, the collector of the third transistor is connected to the third resistor, and the emitter of the third transistor is connected to the first terminal of the feedback module to output the second feedback signal to the feedback module in the on state. The third resistor is disposed between the collector of the third transistor and the first terminal of the first capacitor.

7. The protection circuit according to claim 6, characterized in that, When there is no overload at the output port, the first feedback signal is used to control the output voltage of the output port to increase or decrease. When an overload occurs at the output port, the first feedback signal is used to control the output voltage of the output port to decrease.

8. The protection circuit according to claim 7, characterized in that, When the output voltage of the output port decreases to a first preset threshold voltage, the pulse width modulation control module controls the output voltage of the output port to decrease according to the first feedback signal and the second feedback signal. When the output voltage at the output port decreases to the second preset threshold voltage, the pulse width modulation control module controls the output voltage at the output port to decrease according to the second feedback signal.

9. The protection circuit according to claim 6, characterized in that, When there is no overload at the output port, the first feedback signal is used to control the output voltage of the output port to increase or decrease. When an overload occurs at the output port, the second feedback signal is used to control the output voltage of the output port to decrease.

10. The protection circuit according to any one of claims 1 to 9, characterized in that, The overload of the output port includes: The output current of the output port exceeds a preset current threshold; or When the output current of the output port is close to 0, the operating frequency of the pulse width modulation control module exceeds the preset frequency threshold.

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