A load condition detection circuit and electronic device

Abstract

The present invention discloses a load state detection circuit and an electronic device, wherein the detection circuit comprises a control unit, a voltage detection unit, a constant current source, a switch control unit and a load on-off unit; the voltage detection unit is used to detect the voltage at the external interface and output the detection value to the control unit; the constant current source is used to provide a constant current to the external interface after being turned on; the load on-off unit is used to connect or disconnect the internal circuit with the external interface according to a control signal; and the control unit is used to control the constant current source and the load on-off unit to work through the switch control unit. The present application solves the technical problem that the external interface state of an electronic device cannot be detected under the premise of ensuring that the electronic device is not damaged in the prior art, and achieves the technical effect of protecting the electronic device from damage, accurately and efficiently detecting the external interface state of the electronic device online in real time, and having a small size and low cost.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of load state detection, and in particular to a load state detection circuit and an electronic device. Background Art

[0002] At present, electronic equipment is widely used, and the requirements for the intelligence of electronic equipment are getting higher and higher. The detection and protection of external interfaces in the equipment functions are becoming more and more important. The external interfaces of electronic equipment are used for external loads, but there are often problems with misconnection, such as short circuits and other faults, which cause damage to electronic equipment, and more seriously may cause personal injury to users. In the field of automotive electronics, there are dual requirements of national standards and enterprise standards. It is necessary to conduct electrical performance tests on the external interfaces of the equipment, and at the same time, it is necessary to ensure that the equipment cannot be damaged. Therefore, the protection requirements for the external interfaces are higher.

[0003] At present, various measures have been taken to prevent misconnection of external interfaces of electronic equipment, such as connector anti-misconnection, fuses, high-power TVS (Transient Voltage Suppressor), capacitor isolation, active clamping, etc. However, the above-mentioned misconnection prevention methods all have certain problems. For example: connector anti-misconnection cannot protect a single interface pin; self-recovery fuses and high-power TVS are expensive and large in size, and there are parasitic capacitances that affect the transmission of audio signals, etc.; capacitor isolation is only applicable to AC signals and will cause signal distortion; active clamping can easily damage the circuit board if it is misconnected when the device is not powered on. Summary of the invention

[0004] The present invention provides a load state detection circuit and an electronic device, which solves the technical problem in the prior art that the external interface state of an electronic device cannot be detected under the premise of ensuring that the device is not damaged, and achieves the technical effect of protecting the electronic device from damage and accurately and efficiently detecting the external interface state of the electronic device in real time online, with small size and low cost.

[0005] An embodiment of the present invention provides a load state detection circuit, which is applied to electronic equipment, wherein the detection circuit includes a control unit, a voltage detection unit, a constant current source, a switch control unit, and a load on-off unit;

[0006] The voltage detection unit is electrically connected to the external interface of the electronic device and the control unit, and is used to detect the voltage at the external interface and output the detection value to the control unit;

[0007] The constant current source is electrically connected to the external interface, and the constant current source is used to provide a constant current to the external interface after being turned on;

[0008] The load on-off unit is connected between the internal circuit of the electronic device and the external interface, and is used to connect or disconnect the internal circuit and the external interface according to a control signal;

[0009] The control unit is connected to the constant current source and the load on-off unit through the switch control unit, and is used to control the operation of the constant current source and the load on-off unit through the switch control unit.

[0010] Further, the constant current source includes a first power supply, a first resistor, a second resistor, a first triode, a second triode and a first diode;

[0011] The first end of the first resistor is electrically connected to the first power supply, and the second end of the first resistor is electrically connected to the base of the first transistor; the emitter of the first transistor is electrically connected to the first power supply, and the collector of the first transistor is electrically connected to the first end of the second resistor; the second end of the second resistor is electrically connected to the switch control unit;

[0012] The emitter of the second transistor is electrically connected to the second end of the first resistor, the base of the second transistor is electrically connected to the first end of the second resistor, the collector of the second transistor is electrically connected to the anode of the first diode, and the cathode of the first diode is electrically connected to the external interface.

[0013] Furthermore, the switch control unit includes a first switch tube, a second switch tube, a third switch tube, a second diode and a third diode;

[0014] The control end of the first switch tube is electrically connected to the control unit, the first end of the first switch tube is electrically connected to the constant current source, and the second end of the first switch tube is grounded;

[0015] The control end of the second switch tube is electrically connected to the control unit, the first end of the second switch tube is electrically connected to the negative electrode of the external interface, and the second end of the second switch tube is grounded;

[0016] The control end of the third switch tube is electrically connected to the control unit, the first end of the third switch tube is electrically connected to the load switching unit, and the second end of the third switch tube is grounded;

[0017] The cathode of the second diode and the cathode of the third diode are both electrically connected to the control end of the third switch tube, the anode of the second diode is electrically connected to the anode of the external interface, and the anode of the third diode is electrically connected to the cathode of the external interface.

[0018] Furthermore, the switch control unit further includes a fourth diode, a third resistor, a fourth resistor and a fifth resistor;

[0019] The anode of the fourth diode is electrically connected to the control unit, and the cathode of the fourth diode is electrically connected to the control end of the third switch tube;

[0020] A first end of the third resistor is electrically connected to the constant current source, and a second end of the third resistor is electrically connected to the positive electrode of the external interface;

[0021] The first end of the fourth resistor is electrically connected to the first end of the second switch tube, and the second end of the fourth resistor is electrically connected to the negative electrode of the external interface;

[0022] The first end of the fifth resistor is electrically connected to the control end of the third switch tube, and the second end of the fifth resistor is electrically connected to the cathode of the second diode and the cathode of the third diode respectively.

[0023] Further, the load on-off unit includes a second power supply, a sixth resistor, a seventh resistor, a third transistor, a fourth transistor, a fifth transistor, a first field effect transistor, a second field effect transistor, a third field effect transistor and a fourth field effect transistor;

[0024] The first end of the sixth resistor and the first end of the seventh resistor are both electrically connected to the second power supply, the second end of the sixth resistor is electrically connected to the collector of the third transistor, and the second end of the seventh resistor is electrically connected to the base of the fourth transistor;

[0025] The emitter of the third transistor is electrically connected to the emitter of the fourth transistor, and the collector of the fourth transistor is electrically connected to the source of the first field effect transistor and the source of the second field effect transistor;

[0026] The base of the fifth transistor is electrically connected to the second end of the seventh resistor, the emitter of the fifth transistor is electrically connected to the emitter of the third transistor, and the collector of the fifth transistor is electrically connected to the source of the third field effect transistor and the source of the fourth field effect transistor;

[0027] The gate of the first field effect transistor and the gate of the second field effect transistor are both electrically connected to the emitter of the fourth triode, the drain of the first field effect transistor is electrically connected to the negative electrode of the input interface, and the drain of the second field effect transistor is electrically connected to the negative electrode of the external interface;

[0028] The gate of the third field effect transistor and the gate of the fourth field effect transistor are both electrically connected to the emitter of the fifth transistor, the drain of the third field effect transistor is electrically connected to the positive electrode of the input interface, and the drain of the fourth field effect transistor is electrically connected to the positive electrode of the external interface.

[0029] Furthermore, the load switching unit further includes a first voltage regulator tube and a second voltage regulator tube;

[0030] The cathode of the first voltage regulator is electrically connected to the gate of the first field effect transistor and the gate of the second field effect transistor, and the anode of the first voltage regulator is electrically connected to the source of the first field effect transistor and the source of the second field effect transistor;

[0031] The cathode of the second voltage regulator is electrically connected to the gate of the third field effect tube and the gate of the fourth field effect tube, and the anode of the second voltage regulator is electrically connected to the source of the third field effect tube and the source of the fourth field effect tube.

[0032] Further, the voltage detection unit includes a third power supply, a fourth switch tube and a fifth switch tube;

[0033] The control end of the fourth switch tube and the control end of the fifth switch tube are both electrically connected to the third power supply, the first end of the fourth switch tube is electrically connected to the negative electrode of the external interface, the second end of the fourth switch tube is electrically connected to the control unit, the first end of the fifth switch tube is electrically connected to the positive electrode of the external interface, and the second end of the fifth switch tube is electrically connected to the control unit.

[0034] Further, the first switch tube includes a sixth transistor, an eighth resistor and a ninth resistor; the second switch tube includes a seventh transistor, a tenth resistor and an eleventh resistor; the third switch tube includes an eighth transistor, a twelfth resistor and a thirteenth resistor;

[0035] The collector of the sixth triode is the first end of the first switch tube, the emitter of the sixth triode is the second end of the first switch tube, the eighth resistor is connected between the emitter and the base of the sixth triode, the first end of the ninth resistor is electrically connected to the base of the sixth triode, and the second end of the ninth resistor is the control end of the first switch tube;

[0036] The collector of the seventh triode is the first end of the second switch tube, the emitter of the seventh triode is the second end of the second switch tube, the tenth resistor is connected between the emitter and the base of the seventh triode, the first end of the eleventh resistor is electrically connected to the base of the seventh triode, and the second end of the eleventh resistor is the control end of the second switch tube;

[0037] The collector of the eighth transistor is the first end of the third switch tube, the emitter of the eighth transistor is the second end of the third switch tube, the twelfth resistor is connected between the emitter and the base of the eighth transistor, the first end of the thirteenth resistor is electrically connected to the base of the eighth transistor, and the second end of the thirteenth resistor is the control end of the third switch tube.

[0038] Further, the fourth switch tube includes a ninth transistor, a fourteenth resistor and a fifteenth resistor; the fifth switch tube includes a tenth transistor, a sixteenth resistor and a seventeenth resistor;

[0039] The collector of the ninth triode is the first end of the fourth switch tube, the emitter of the ninth triode is the second end of the fourth switch tube, the fourteenth resistor is connected between the emitter and the base of the ninth triode, the first end of the fifteenth resistor is electrically connected to the base of the ninth triode, and the second end of the fifteenth resistor is the control end of the fourth switch tube;

[0040] The collector of the thirteenth transistor is the first end of the fifth switch tube, the emitter of the thirteenth transistor is the second end of the fifth switch tube, the sixteenth resistor is connected between the emitter and the base of the thirteenth transistor, the first end of the seventeenth resistor is electrically connected to the base of the thirteenth transistor, and the second end of the seventeenth resistor is the control end of the fifth switch tube.

[0041] An embodiment of the present invention further provides an electronic device, wherein the electronic device includes the load state detection circuit described in any one of the above embodiments.

[0042] The present invention discloses a load state detection circuit and an electronic device, wherein the detection circuit comprises a control unit, a voltage detection unit, a constant current source, a switch control unit and a load on-off unit; the voltage detection unit is used to detect the voltage at the external interface and output the detection value to the control unit; the constant current source is used to provide a constant current to the external interface after being turned on; the load on-off unit is used to connect or disconnect the internal circuit with the external interface according to a control signal; and the control unit is used to control the constant current source and the load on-off unit to work through the switch control unit. The present application solves the technical problem that the external interface state of an electronic device cannot be detected under the premise of ensuring that the electronic device is not damaged in the prior art, and achieves the technical effect of protecting the electronic device from damage, accurately and efficiently detecting the external interface state of the electronic device online in real time, and having a small size and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a structural diagram of a load state detection circuit provided by an embodiment of the present invention;

[0044] Figure 2 is a circuit diagram of a load state detection circuit provided by an embodiment of the present invention;

[0045] Figure 3 This is a working flow chart of a load state detection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0047] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish different objects, rather than to limit a specific order. The following embodiments of the present invention can be implemented separately, or in combination with each other, and the embodiments of the present invention do not impose specific limitations on this.

[0048] Figure 1 It is a structural diagram of a load state detection circuit provided by an embodiment of the present invention.

[0049] like Figure 1 As shown, the load state detection circuit is applied to electronic equipment, and includes a control unit 10 , a voltage detection unit 20 , a constant current source 30 , a switch control unit 40 and a load on-off unit 50 .

[0050] The voltage detection unit 20 is electrically connected to the external interface 60 of the electronic device and the control unit 10, and is used to detect the voltage at the external interface 60 and transmit the detection value to the control unit 10; the constant current source 30 is electrically connected to the external interface 60, and the constant current source 30 is used to provide a constant current to the external interface 60 after being turned on; the load on-off unit 50 is connected between the internal circuit of the electronic device and the external interface 60, and the load on-off unit 50 is used to connect or disconnect the internal circuit and the external interface 60 according to a control signal; the control unit 10 is connected to the constant current source 30 and the load on-off unit 50 through the switch control unit 40, and is used to control the operation of the constant current source 30 and the load on-off unit 50 through the switch control unit 40.

[0051] Specifically, the voltage detection unit 20 can condition and obtain the voltage on the external interface 60, and transmit the obtained voltage value (i.e., the above-mentioned detection value) to the control unit 10 to realize voltage detection on the external interface 60; the so-called "conditioning" refers to the fact that the voltage detection unit 20 is provided with a transistor and a power supply (i.e., the transistor in the fourth switch tube, the transistor in the fifth switch tube and the third power supply described below). The transistor can control the voltage detection unit 20 to output a voltage value to the control unit 10 not exceeding the voltage value of the third power supply when the voltage of the external interface 60 is too high, thereby realizing protection of the acquisition pin of the control unit 10.

[0052] The control unit 10 can enable the external interface 60 so that the connection between the external interface 60 and the internal circuit of the electronic device is disconnected at the beginning of the detection to protect the electronic device from being damaged when the load connected to the external interface 60 is detected. The control unit 10 can also determine the load state at the external interface 60 based on the received detection value, such as short circuit, open circuit, overvoltage, overcurrent and normal state. The control unit 10 can be composed of a single-chip microcomputer, a CPU, a PLC, etc., and can have the function of outputting control signals and performing ADC (Analog-to-Digital Converter) detection of voltage signals; after the control unit 10 determines the state of the load, it sends a control signal to the switch control unit 40 based on the load state, and can report the determined load state information to other electronic units or display screens connected to the control unit 10 ( Figure 1 Not shown in the figure) to remind the user that there is an error so that he can correct it in time.

[0053] The constant current source 30 is used to provide a constant current to the load at the external interface 60. When performing load status detection, the control unit 10 will first disconnect the external interface 60 and the internal circuit of the electronic device through the load on-off unit 50. Since the constant current source 30 is set, the voltage value can still be detected on the load after disconnecting from the internal circuit, that is, the above-mentioned detection value, thereby achieving protection of the electronic device when detecting the external interface 60.

[0054] The switch control unit 40 is responsible for converting the overvoltage feedback signal and the control signal sent by the control unit 10, that is, when an overvoltage fault occurs in the load at the external interface 60, the load on-off unit 50 can be controlled to be turned on and off based on the received control signal. The load on-off unit 50 can open the connection between the external interface 60 and the load when the load state is normal, and can automatically disconnect the external interface 60 from the load when an overvoltage fault occurs in the load. The load on-off unit 50 can also realize the on-off control of the load based on the control of the switch control unit 40.

[0055] In an embodiment of the present invention, by disconnecting the load and the internal circuit of the electronic device when detecting the state of the load, a constant current source is applied to the load, the voltage information of the external interface connected to the load is analyzed, and the state information of the load is determined, thereby achieving the ability to protect the internal circuit of the electronic device connected to the external interface, solving the technical problem in the prior art that the state of the external interface of the electronic device cannot be detected under the premise of ensuring that the electronic device is not damaged, and achieving the technical effect of protecting the electronic device from damage and accurately and efficiently detecting the state of the external interface of the electronic device online in real time, with a small size and low cost.

[0056] Figure 2 It is a circuit diagram of a load state detection circuit provided by an embodiment of the present invention.

[0057] Alternatively, if Figure 2 As shown, the constant current source 30 includes a first power source VCC1, a first resistor R1, a second resistor R2, a first transistor Q1, a second transistor Q2 and a first diode D1.

[0058] The first end of the first resistor R1 is electrically connected to the first power supply VCC1, and the second end of the first resistor R1 is electrically connected to the base of the first transistor Q1; the emitter of the first transistor Q1 is electrically connected to the first power supply VCC1, and the collector of the first transistor Q1 is electrically connected to the first end of the second resistor R2; the second end of the second resistor R2 is electrically connected to the switch control unit 40.

[0059] The emitter of the second transistor Q2 is electrically connected to the second end of the first resistor R1, the base of the second transistor Q2 is electrically connected to the first end of the second resistor R2, the collector of the second transistor Q2 is electrically connected to the anode of the first diode D1, and the cathode of the first diode D1 is electrically connected to the external interface 60.

[0060] Specifically, the constant current source 30 is composed of a first power source VCC1 through a first resistor R1, a first transistor Q1, a second transistor Q2, a second resistor R2 and a first diode D2. Figure 2 Taking the first transistor Q1 and the second transistor Q2 as PNP transistors as an example, when the voltage drop between the base and the emitter of the first transistor Q1 is greater than about 0.7V, the second transistor Q2 will be turned off, thereby realizing constant current. The constant current source 30 can provide a constant current of about 0.7 / R1 to the positive electrode of the load through the external interface 60.

[0061] Alternatively, if Figure 2 As shown, the switch control unit 40 includes a first switch tube Q3, a second switch tube Q4, a third switch tube Q5, a second diode D2 and a third diode D3.

[0062] The control end of the first switch tube Q3 is electrically connected to the control unit 10, the first end of the first switch tube Q3 is electrically connected to the constant current source 30, and the second end of the first switch tube Q3 is grounded; the control end of the second switch tube Q4 is electrically connected to the control unit 10, the first end of the second switch tube Q4 is electrically connected to the negative electrode SPK_O_N of the external interface 60, and the second end of the second switch tube Q4 is grounded; the control end of the third switch tube Q5 is electrically connected to the control unit 10, the first end of the third switch tube Q5 is electrically connected to the load switching unit 50, and the second end of the third switch tube Q5 is grounded; the cathode of the second diode D2 and the cathode of the third diode D3 are both electrically connected to the control end of the third switch tube Q5, the anode of the second diode D2 is electrically connected to the positive electrode SPK_O_P of the external interface 60, and the anode of the third diode D3 is electrically connected to the negative electrode SPK_O_N of the external interface 60.

[0063] Alternatively, if Figure 2 As shown, the first switch tube Q3 includes a sixth transistor q1, an eighth resistor r1 and a ninth resistor r2; the second switch tube Q4 includes a seventh transistor q2, a tenth resistor r3 and an eleventh resistor r4; the third switch tube includes an eighth transistor q3, a twelfth resistor r5 and a thirteenth resistor r6;

[0064] The collector of the sixth triode q1 is the first end of the first switch tube Q3, the emitter of the sixth triode q1 is the second end of the first switch tube Q3, the eighth resistor r1 is connected between the emitter and the base of the sixth triode q1, the first end of the ninth resistor r2 is electrically connected to the base of the sixth triode q1, and the second end of the ninth resistor r2 is the control end of the first switch tube Q3;

[0065] The collector of the seventh triode q2 is the first end of the second switch tube Q4, the emitter of the seventh triode q2 is the second end of the second switch tube Q4, the tenth resistor r3 is connected between the emitter and the base of the seventh triode q2, the first end of the eleventh resistor r4 is electrically connected to the base of the seventh triode q2, and the second end of the eleventh resistor r4 is the control end of the second switch tube Q4;

[0066] The collector of the eighth triode q3 is the first end of the third switch tube Q5, the emitter of the eighth triode q3 is the second end of the third switch tube Q5, the twelfth resistor r5 is connected between the emitter and the base of the eighth triode q3, the first end of the thirteenth resistor r6 is electrically connected to the base of the eighth triode q3, and the second end of the thirteenth resistor r6 is the control end of the third switch tube.

[0067] Alternatively, if Figure 2 As shown, the switch control unit 40 further includes a fourth diode D4, a third resistor R3, a fourth resistor R4 and a fifth resistor R5.

[0068] The anode of the fourth diode D4 is electrically connected to the control unit 10, and the cathode of the fourth diode D4 is electrically connected to the control end of the third switch tube Q5; the first end of the third resistor R3 is electrically connected to the constant current source 30, and the second end of the third resistor R3 is electrically connected to the anode SPK_O_P of the external interface 60; the first end of the fourth resistor R4 is electrically connected to the first end of the second switch tube Q4, and the second end of the fourth resistor R4 is electrically connected to the cathode SPK_O_N of the external interface 60; the first end of the fifth resistor R5 is electrically connected to the control end of the third switch tube Q5, and the second end of the fifth resistor R5 is electrically connected to the cathode of the second diode D2 and the cathode of the third diode D3, respectively.

[0069] For example, see Figure 2 When the output signal SPK_DET_EN of the control unit 10 is set to a high level, the collectors and emitters of the first switch tube Q3, the second switch tube Q4 and the third switch tube Q5 are saturated and conducted, and the constant current source 30 flows to the load at the positive electrode SPK_O_P of the external interface 60 through the third resistor R3, and then flows through the load at the negative electrode SPK_O_N of the external interface 60 and the fourth resistor R4 through the collector of the second switch tube Q4, and finally flows into the ground terminal GND. When an overvoltage fault occurs at the external interface 60, the second diode D2 and the third diode D3 are forward-conducted, and the collector and emitter of the third switch tube Q5 are turned on through the fifth resistor R5, and the third transistor Q6 in the load on-off unit 50 is turned off. At the same time, the collector and emitter of the fourth transistor Q7 and the fifth transistor Q8 in the load on-off unit 50 are turned on, so that the first field effect transistor Q9, the second field effect transistor Q10, the third field effect transistor Q11 and the fourth field effect transistor Q12 in the load on-off unit 50 are all turned off, so that the load on-off unit 50 is turned off, and the external interface 60 is disconnected from the load.

[0070] Alternatively, if Figure 2 As shown, the load on-off unit 50 includes a second power supply VCC2, a sixth resistor R6, a seventh resistor R7, a third transistor Q6, a fourth transistor Q7, a fifth transistor Q8, a first field effect transistor Q9, a second field effect transistor Q10, a third field effect transistor Q11 and a fourth field effect transistor Q12.

[0071] The first end of the sixth resistor R6 and the first end of the seventh resistor R7 are both electrically connected to the second power supply VCC2, the second end of the sixth resistor R6 is electrically connected to the collector of the third transistor Q6, and the second end of the seventh resistor R7 is electrically connected to the base of the fourth transistor Q7; the emitter of the third transistor Q6 is electrically connected to the emitter of the fourth transistor Q7, and the collector of the fourth transistor Q7 is electrically connected to the source of the first field effect transistor Q9 and the source of the second field effect transistor Q10.

[0072] The base of the fifth transistor Q8 is electrically connected to the second end of the seventh resistor, the emitter of the fifth transistor Q8 is electrically connected to the emitter of the third transistor Q6, and the collector of the fifth transistor Q8 is electrically connected to the source of the third field effect transistor Q11 and the source of the fourth field effect transistor Q12.

[0073] The gate of the first field effect transistor Q9 and the gate of the second field effect transistor Q10 are both electrically connected to the emitter of the fourth transistor Q7, the drain of the first field effect transistor Q9 is electrically connected to the cathode SPK_N of the input interface, and the drain of the second field effect transistor Q10 is electrically connected to the cathode SPK_O_N of the external interface 60.

[0074] The gate of the third field effect transistor Q11 and the gate of the fourth field effect transistor Q12 are both electrically connected to the emitter of the fifth transistor Q8, the drain of the third field effect transistor Q11 is electrically connected to the positive electrode SPK_P of the input interface, and the drain of the fourth field effect transistor Q12 is electrically connected to the positive electrode SPK_O_P of the external interface 60.

[0075] Specifically, the second power supply VCC2 can drive the first field effect transistor Q9 and the second field effect transistor Q10 to be turned on and off through the totem pole driving circuit composed of the sixth resistor R6, the seventh resistor R7, the third transistor Q6 and the fourth transistor Q7, and VCC1 can drive the third field effect transistor Q11 and the fourth field effect transistor Q12 to be turned on and off through the totem pole driving circuit composed of the sixth resistor R6, the seventh resistor R7, the third transistor Q6 and the fifth transistor Q8, thereby realizing the connection and disconnection of the external interface 60 with the load.

[0076] Optionally, the load on-off unit 50 also includes a first voltage regulator tube D5 and a second voltage regulator tube D6; the cathode of the first voltage regulator tube D5 is electrically connected to the gate of the first field effect tube Q9 and the gate of the second field effect tube Q10, and the anode of the first voltage regulator tube D6 is electrically connected to the source of the first field effect tube Q9 and the source of the second field effect tube Q10; the cathode of the second voltage regulator tube D6 is electrically connected to the gate of the third field effect tube Q11 and the gate of the fourth field effect tube Q12, and the anode of the second voltage regulator tube D6 is electrically connected to the source of the third field effect tube Q11 and the source of the fourth field effect tube Q12.

[0077] Specifically, the first voltage-stabilizing tube D5 is used to prevent the gate-source voltage of the first field effect tube Q9 and the second field effect tube Q10 from being too high, thereby protecting the first field effect tube Q9 and the second field effect tube Q10 from being damaged due to overvoltage; the second voltage-stabilizing tube D6 is used to prevent the gate-source voltage of the third field effect tube Q11 and the fourth field effect tube Q12 from being too high, thereby protecting the first field effect tube Q11 and the fourth field effect tube Q12 from being damaged due to overvoltage.

[0078] Alternatively, if Figure 2As shown, the voltage detection unit 20 includes a third power supply VCC3, a fourth switch tube Q13 and a fifth switch tube Q14; the control end of the fourth switch tube Q13 and the control end of the fifth switch tube Q14 are both electrically connected to the third power supply VCC3, the first end of the fourth switch tube Q13 is electrically connected to the negative electrode SPK_O_N of the external interface 60, the second end of the fourth switch tube Q13 is electrically connected to the control unit 10, the first end of the fifth switch tube Q14 is electrically connected to the positive electrode SPK_O_P of the external interface 60, and the second end of the fifth switch tube Q14 is electrically connected to the control unit 10.

[0079] Optionally, the fourth switch tube Q13 includes a ninth transistor q4, a fourteenth resistor r7 and a fifteenth resistor r8; the fifth switch tube Q14 includes a tenth transistor q5, a sixteenth resistor r9 and a seventeenth resistor r10;

[0080] The collector of the ninth transistor q4 is the first end of the fourth switch tube Q13, the emitter of the ninth transistor q4 is the second end of the fourth switch tube Q13, the fourteenth resistor r7 is connected between the emitter and the base of the ninth transistor q4, the first end of the fifteenth resistor r8 is electrically connected to the base of the ninth transistor q4, and the second end of the fifteenth resistor r8 is the control end of the fourth switch tube Q13.

[0081] The collector of the thirteenth transistor q5 is the first end of the fifth switch tube Q14, the emitter of the thirteenth transistor q5 is the second end of the fifth switch tube Q14, the sixteenth resistor r9 is connected between the emitter and the base of the thirteenth transistor q5, the first end of the seventeenth resistor r10 is electrically connected to the base of the thirteenth transistor q5, and the second end of the seventeenth resistor r10 is the control end of the fifth switch tube Q14.

[0082] Specifically, the second end of the fourth switch tube Q13 is electrically connected to the negative sampling end SPK_ADC_N of the control unit 10, and the second end of the fifth switch tube Q14 is electrically connected to the positive sampling end SPK_ADC_P of the control unit 10. The voltage detection unit 20 can realize that the positive and negative sampling ends of the control unit 10 will not be damaged due to the excessive voltage of the external interface 60 when collecting the voltage of the external interface 60 through the control of the transistors in the fourth switch tube Q13 and the fifth switch tube Q14. Specifically, when the voltage at the external interface 60 is too high, the transistors in the fourth switch tube Q13 and the fifth switch tube Q14 are cut off, and the voltage values ​​obtained by the positive and negative sampling ends of the control unit 10 are at most the value of the third power supply VCC3. When the voltage value obtained by the control unit 10 is the voltage value of the third power supply VCC3, it indicates that an overvoltage phenomenon occurs at the external interface 60.

[0083] Figure 3 This is a working flow chart of a load state detection circuit provided by an embodiment of the present invention.

[0084] The following is a specific example to describe the working process of the load state detection circuit. Figure 3 As shown, the working process of the load state detection circuit includes the following steps:

[0085] Step S301, detect whether the external interface is in overvoltage, if the judgment result is yes, execute step S302, otherwise execute step S303.

[0086] Step S302: the load on / off unit 50 automatically disconnects the external interface 60 from the internal circuit of the electronic device.

[0087] Step S303 : the control unit 10 disconnects the external interface 60 from the internal circuit of the electronic device.

[0088] Step S304 , turning on the current source 30 .

[0089] In step S305 , the voltage detection unit 20 collects the voltage value of the external interface 60 (ie, the above-mentioned detection value), and transmits the collected voltage value to the control unit 10 .

[0090] In step S306 , the control unit 10 determines the state of the external interface 60 based on the received voltage value.

[0091] Specifically, see Figure 2, when the IO output control terminal SPK_DET_EN in the control unit 10 is set to a high level, (1) when the voltage value collected by the negative sampling terminal SPK_ADC_N is approximately (0.7 / R1)*R4+0.3, and the voltage value collected by the positive sampling terminal SPK_ADC_P is approximately (0.7 / R1)*R40.3+(0.7 / R1)*RL, the judgment result is that the load is in a normal state, where RL is the resistance of the load; (2) when the voltage value collected by the positive sampling terminal SPK_ADC_P is equal to the voltage value collected by the negative sampling terminal SPK_ADC_N, and is approximately (0.7 / R1)*R4+0.3, the judgment result is that the load on the positive SPK_O_P and negative SPK_O_N interfaces of the external interface 60 is short-circuited; (3) when the positive sampling terminal SPK_ADC_P collects the voltage value collected by the positive sampling terminal SPK_ADC_P, the load on the positive SPK_O_P and negative SPK_O_N interfaces of the external interface 60 is short-circuited. When the collected voltage value is approximately VCC2-0.7-0.3-0.3 and the voltage value collected by the negative sampling terminal SPK_ADC_N is 0V, the judgment result is that the load on the positive SPK_O_P and negative SPK_O_N interfaces of the external interface 60 is disconnected; (4) When the collected voltage value by the positive sampling terminal SPK_ADC_P is approximately VCC3 and the collected voltage value by the negative sampling terminal SPK_ADC_N is 0V, the judgment result is that the positive SPK_O_P interface of the external interface 60 is short-circuited to the power supply and the load is disconnected; (5) When the collected voltage value by the positive sampling terminal SPK_ADC_P is approximately VCC2-0.7-0.3-0.3 and the collected voltage value by the negative sampling terminal SPK_ADC_N is VCC3, the negative SPK_O_N interface of the external interface 60 is short-circuited to the power supply and the load is disconnected.

[0092] (6) When the positive electrode SPK_O_P or the negative electrode SPK_O_N interface of the external interface 60 is short-circuited to the power supply, the second diode D2 and the third diode D3 are forward-conducted, and the third switch tube Q5 is driven to be saturated and turned on through the fifth resistor R5, and the first field effect tube Q9, the second field effect tube Q10, the third field effect tube Q11, and the fourth field effect tube Q12 are turned off to protect the internal circuit of the electronic device. At the same time, the voltage value collected by the positive sampling terminal SPK_ADC_P of the control unit 10 or the voltage value collected by the negative sampling terminal SPK_ADC_N is approximately VCC3, and the control unit 10 sets the SPK_DET_EN signal to a low level to turn off the second switch tube Q4 to avoid damage to the fourth resistor R4 and the second switch tube Q4.

[0093] (7) When the positive SPK_O_P or negative SPK_O_N interface of the external interface 60 is short-circuited to the ground, the voltage value collected by the positive sampling terminal SPK_ADC_P of the control unit 10 is equal to the voltage value collected by the negative sampling terminal SPK_ADC_N, and is approximately 0V. At this time, the control unit 10 sets the SPK_DET_EN signal to a high level, turns off the first field effect transistor Q9, the second field effect transistor Q10, the third field effect transistor Q11, and the fourth field effect transistor Q12 to protect the internal circuit of the electronic device.

[0094] In step S307, the control unit 10 sends a control signal to the switch control unit 40 based on the judgment result, so as to realize the conduction and disconnection between the external interface 60 and the load by controlling the load on-off unit 50, and at the same time reports the judgment result to other electronic units or display screens connected to the control unit 10 to remind the user that there is an error so as to correct it in time.

[0095] An embodiment of the present invention further provides an electronic device, the electronic device comprising the load state detection circuit described in any of the above embodiments.

[0096] The electronic device provided by the embodiment of the present invention includes the load state detection circuit in the above embodiment, so the electronic device provided by the embodiment of the present invention also has the beneficial effects described in the above embodiment, which will not be described in detail here.

[0097] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0098] Finally, it should be noted that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A load state detection circuit, applied to electronic equipment, characterized in that: The detection circuit includes a control unit, a voltage detection unit, a constant current source, a switch control unit and a load on-off unit; The voltage detection unit is electrically connected to the external interface of the electronic device and the control unit, and is used to detect the voltage at the external interface and output the detection value to the control unit; The constant current source is electrically connected to the external interface, and the constant current source is used to provide a constant current to the external interface after being turned on; The load on-off unit is connected between the internal circuit of the electronic device and the external interface, and is used to connect or disconnect the internal circuit and the external interface according to a control signal; The control unit is connected to the constant current source and the load on-off unit through the switch control unit, and is used to control the operation of the constant current source and the load on-off unit through the switch control unit; The switch control unit includes a first switch tube, a second switch tube, a third switch tube, a second diode and a third diode; The control end of the first switch tube is electrically connected to the control unit, the first end of the first switch tube is electrically connected to the constant current source, and the second end of the first switch tube is grounded; The control end of the second switch tube is electrically connected to the control unit, the first end of the second switch tube is electrically connected to the negative electrode of the external interface, and the second end of the second switch tube is grounded; The control end of the third switch tube is electrically connected to the control unit, the first end of the third switch tube is electrically connected to the load switching unit, and the second end of the third switch tube is grounded; The cathode of the second diode and the cathode of the third diode are both electrically connected to the control end of the third switch tube, the anode of the second diode is electrically connected to the anode of the external interface, and the anode of the third diode is electrically connected to the cathode of the external interface; The first switch tube includes a sixth transistor, an eighth resistor and a ninth resistor; the second switch tube includes a seventh transistor, a tenth resistor and an eleventh resistor; the third switch tube includes an eighth transistor, a twelfth resistor and a thirteenth resistor; The collector of the sixth triode is the first end of the first switch tube, the emitter of the sixth triode is the second end of the first switch tube, the eighth resistor is connected between the emitter and the base of the sixth triode, the first end of the ninth resistor is electrically connected to the base of the sixth triode, and the second end of the ninth resistor is the control end of the first switch tube; The collector of the seventh triode is the first end of the second switch tube, the emitter of the seventh triode is the second end of the second switch tube, the tenth resistor is connected between the emitter and the base of the seventh triode, the first end of the eleventh resistor is electrically connected to the base of the seventh triode, and the second end of the eleventh resistor is the control end of the second switch tube; The collector of the eighth transistor is the first end of the third switch tube, the emitter of the eighth transistor is the second end of the third switch tube, the twelfth resistor is connected between the emitter and the base of the eighth transistor, the first end of the thirteenth resistor is electrically connected to the base of the eighth transistor, and the second end of the thirteenth resistor is the control end of the third switch tube.

2. The detection circuit according to claim 1, characterized in that: The constant current source comprises a first power supply, a first resistor, a second resistor, a first triode, a second triode and a first diode; The first end of the first resistor is electrically connected to the first power supply, and the second end of the first resistor is electrically connected to the base of the first transistor; the emitter of the first transistor is electrically connected to the first power supply, and the collector of the first transistor is electrically connected to the first end of the second resistor; the second end of the second resistor is electrically connected to the switch control unit; The emitter of the second transistor is electrically connected to the second end of the first resistor, the base of the second transistor is electrically connected to the first end of the second resistor, the collector of the second transistor is electrically connected to the anode of the first diode, and the cathode of the first diode is electrically connected to the external interface.

3. The detection circuit according to claim 1, characterized in that: The switch control unit further includes a fourth diode, a third resistor, a fourth resistor and a fifth resistor; The anode of the fourth diode is electrically connected to the control unit, and the cathode of the fourth diode is electrically connected to the control end of the third switch tube; A first end of the third resistor is electrically connected to the constant current source, and a second end of the third resistor is electrically connected to the positive electrode of the external interface; The first end of the fourth resistor is electrically connected to the first end of the second switch tube, and the second end of the fourth resistor is electrically connected to the negative electrode of the external interface; The first end of the fifth resistor is electrically connected to the control end of the third switch tube, and the second end of the fifth resistor is electrically connected to the cathode of the second diode and the cathode of the third diode respectively.

4. The detection circuit according to claim 1, characterized in that: The load on-off unit includes a second power supply, a sixth resistor, a seventh resistor, a third transistor, a fourth transistor, a fifth transistor, a first field effect transistor, a second field effect transistor, a third field effect transistor and a fourth field effect transistor; The first end of the sixth resistor and the first end of the seventh resistor are both electrically connected to the second power supply, the second end of the sixth resistor is electrically connected to the collector of the third triode, and the second end of the seventh resistor is electrically connected to the base of the fourth triode, the base of the third triode and the switch control unit; The emitter of the third transistor is electrically connected to the emitter of the fourth transistor, and the collector of the fourth transistor is electrically connected to the source of the first field effect transistor and the source of the second field effect transistor; The base of the fifth transistor is electrically connected to the second end of the seventh resistor, the emitter of the fifth transistor is electrically connected to the emitter of the third transistor, and the collector of the fifth transistor is electrically connected to the source of the third field effect transistor and the source of the fourth field effect transistor; The gate of the first field effect transistor and the gate of the second field effect transistor are both electrically connected to the emitter of the fourth triode, the drain of the first field effect transistor is electrically connected to the negative electrode of the input interface, and the drain of the second field effect transistor is electrically connected to the negative electrode of the external interface; The gate of the third field effect transistor and the gate of the fourth field effect transistor are both electrically connected to the emitter of the fifth transistor, the drain of the third field effect transistor is electrically connected to the positive electrode of the input interface, and the drain of the fourth field effect transistor is electrically connected to the positive electrode of the external interface.

5. The detection circuit according to claim 4, characterized in that: The load switching unit further includes a first voltage regulator tube and a second voltage regulator tube; The positive electrode of the first voltage regulator is electrically connected to the gate of the first field effect transistor and the gate of the second field effect transistor, and the negative electrode of the first voltage regulator is electrically connected to the source of the first field effect transistor and the source of the second field effect transistor; The cathode of the second voltage regulator is electrically connected to the gate of the third field effect tube and the gate of the fourth field effect tube, and the anode of the second voltage regulator is electrically connected to the source of the third field effect tube and the source of the fourth field effect tube.

6. The detection circuit according to claim 1, characterized in that: The voltage detection unit includes a third power supply, a fourth switch tube and a fifth switch tube; The control end of the fourth switch tube and the control end of the fifth switch tube are both electrically connected to the third power supply, the first end of the fourth switch tube is electrically connected to the negative electrode of the external interface, the second end of the fourth switch tube is electrically connected to the control unit, the first end of the fifth switch tube is electrically connected to the positive electrode of the external interface, and the second end of the fifth switch tube is electrically connected to the control unit.

7. The detection circuit according to claim 6, characterized in that: The fourth switch tube includes a ninth transistor, a fourteenth resistor and a fifteenth resistor; the fifth switch tube includes a tenth transistor, a sixteenth resistor and a seventeenth resistor; The collector of the ninth triode is the first end of the fourth switch tube, the emitter of the ninth triode is the second end of the fourth switch tube, the fourteenth resistor is connected between the emitter and the base of the ninth triode, the first end of the fifteenth resistor is electrically connected to the base of the ninth triode, and the second end of the fifteenth resistor is the control end of the fourth switch tube; The collector of the thirteenth transistor is the first end of the fifth switch tube, the emitter of the thirteenth transistor is the second end of the fifth switch tube, the sixteenth resistor is connected between the emitter and the base of the thirteenth transistor, the first end of the seventeenth resistor is electrically connected to the base of the thirteenth transistor, and the second end of the seventeenth resistor is the control end of the fifth switch tube.

8. An electronic device, characterized in that: The electronic device comprises the load state detection circuit according to any one of claims 1 to 7.

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