CN112147449A - A load state detection circuit and electronic device - Google Patents

Abstract

The invention discloses a load state detection circuit and electronic equipment, 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 for detecting the voltage at the external interface and outputting the detection value to the control unit; the constant current source is used for supplying constant current to the external interface after being started; the load on-off unit is used for connecting or disconnecting the internal circuit and the external interface according to the control signal; the control unit is used for controlling the constant current source and the load on-off unit to work through the switch control unit. The application solves the technical problem that the external interface state of the electronic equipment cannot be detected on the premise of ensuring that the electronic equipment is not damaged in the prior art, and achieves the technical effects of not only protecting the electronic equipment from being damaged, but also accurately and efficiently detecting the external interface state of the electronic equipment in real time on line, and being small in size and low in cost.

Description

A load state detection circuit and electronic device

technical field

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 technique

At present, electronic equipment is widely used, and the intelligent requirements of electronic equipment are getting higher and higher, and the detection and protection of external interfaces in equipment functions are becoming more and more important. The external interface of electronic equipment is used for external load, but there are often misconnection problems, such as short circuit and other faults, which cause damage to electronic equipment, and may cause personal injury to users more seriously. 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 interface of the equipment, and at the same time, it is necessary to ensure that the equipment cannot be damaged, so the protection requirements for the external interface are higher.

At this stage, various measures have been taken to prevent misconnection of external interfaces of electronic equipment, such as foolproof connectors, fuses, high-power TVS (Transient Voltage Suppressor, transient diodes), capacitive isolation, active clamps, etc., but the above There are certain problems in the anti-misconnection method. For example: the foolproof connector cannot protect a single interface pin; the self-recovery fuse and high-power TVS are expensive and bulky, and there are parasitic capacitances that affect the transmission of audio signals, etc.; capacitive isolation is only suitable for AC signals, and will cause signal damage. Distortion; Active clamps can easily damage the circuit board when the device is not powered on.

SUMMARY OF THE INVENTION

The 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 the electronic device cannot be detected on the premise of ensuring that the device is not damaged, and realizes that both the electronic device can be protected from damage. , and can accurately and efficiently detect the external interface status of electronic equipment online in real time, and has the technical effect of small size and low cost.

An embodiment of the present invention provides a load state detection circuit, which is applied to electronic equipment, and 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 with the external interface of the electronic device and the control unit, and is used for detecting the voltage at the external interface and outputting the detected 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 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 the load on-off unit 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, so as to control the operation of the constant current source and the load on-off unit through the switch control unit.

Further, the constant current source includes a first power supply, a first resistor, a second resistor, a first transistor, a second transistor 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 triode; the emission of the first triode The electrode is electrically connected to the first power supply, 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 triode is electrically connected to the second end of the first resistor, the base of the second triode is electrically connected to the first end of the second resistor, and the second The collector of the triode is electrically connected to the anode of the first diode, and the cathode of the first diode is electrically connected to the external interface.

Further, 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 terminal of the third switch tube, and the anode of the second diode is electrically connected to the anode of the external interface. connected, the anode of the third diode is electrically connected to the cathode of the external interface.

Further, 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 terminal of the third switch tube;

The first end of the third resistor is electrically connected to the constant current source, and the 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 respectively connected to the cathode of the second diode and the third diode negative electrical connection.

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, and a second field effect transistor. tube, the third field effect tube and the fourth field effect tube;

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

The emitter of the third triode is electrically connected to the emitter of the fourth triode, the collector of the fourth triode is connected to the source of the first field effect transistor, the second The source electrode of the FET is electrically connected;

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 third transistor is electrically connected. The collector of the five triode 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, and the drain of the first field effect transistor is connected to the input interface. The negative electrode is electrically connected, and the drain electrode 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 all electrically connected to the emitter of the fifth triode, and the drain of the third field effect transistor is connected to the input interface. The positive electrode is electrically connected, and the drain electrode of the fourth field effect transistor is electrically connected to the positive electrode of the external interface.

Further, the load on-off unit further includes a first voltage regulator tube and a second voltage regulator tube;

The negative electrode of the first voltage regulator is electrically connected to the grid of the first field effect transistor and the grid of the second field effect transistor, and the positive electrode of the first voltage regulator is connected to the first field effect transistor. the source of the tube and the source of the second field effect tube are electrically connected;

The negative electrode of the second voltage regulator is electrically connected to the grid of the third field effect transistor and the grid of the fourth field effect transistor, and the positive electrode of the second voltage regulator is electrically connected to the third field effect transistor The source of the tube and the source of the fourth field effect tube are electrically connected.

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

The control terminal of the fourth switch tube and the control terminal of the fifth switch tube are both electrically connected to the third power supply, and the first end of the fourth switch tube is electrically connected to the negative pole of the external interface, so 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 pole of the external interface, and the second end of the fifth switch tube is electrically connected to the The control unit is electrically connected.

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 The switch tube includes an eighth transistor, a twelfth resistor and a thirteenth resistor;

The collector of the sixth transistor is the first end of the first switch, the emitter of the sixth transistor is the second end of the first switch, and the eighth resistor is connected to 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 transistor is the first end of the second switch, the emitter of the seventh transistor is the second end of the second switch, and the tenth resistor is connected to 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 electrically connected 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, and the twelfth resistor is connected to 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 electrically connected to the base of the eighth transistor. The terminal is the control terminal of the third switch tube.

Further, the fourth switch tube includes a ninth transistor, a fourteenth resistor and a fifteenth resistor; the fifth switch tube includes a thirteenth transistor, a sixteenth resistor and a seventeenth resistor;

The collector of the ninth transistor is the first end of the fourth switch, the emitter of the ninth transistor is the second end of the fourth switch, and the fourteenth resistor is connected to Between the emitter and the base of the ninth transistor, the first end of the fifteenth resistor is electrically connected to the base of the ninth transistor, and the second end of the fifteenth resistor is electrically connected to the base of the ninth transistor. The terminal is the control terminal of the fourth switch tube;

The collector of the thirteenth tube is the first end of the fifth switch tube, the emitter of the thirteenth tube is the second end of the fifth switch tube, and the sixteenth resistor is connected to Between the emitter and the base of the thirteenth tube, the first end of the seventeenth resistor is electrically connected to the base of the thirteenth tube, and the second end of the seventeenth resistor is electrically connected to the base of the thirteenth tube. The terminal is the control terminal of the fifth switch tube.

An embodiment of the present invention further provides an electronic device, where the electronic device includes the load state detection circuit described in any of the foregoing embodiments.

The invention discloses a load state detection circuit and electronic equipment. 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 used to detect the voltage at an external interface, and Output the detected value to the control unit; the constant current source is used to provide constant current to the external interface after being turned on; the load on-off unit is used to connect or disconnect the internal circuit and the external interface according to the control signal; the control unit is used to pass the switch The control unit controls the constant current source and the load on-off unit to work. The present application solves the technical problem in the prior art that the state of the external interface of the electronic device cannot be detected on the premise of ensuring that the electronic device is not damaged, and realizes the real-time online detection that can not only protect the electronic device from damage, but also is accurate and efficient. The external interface state of electronic equipment, and the technical effect of small size and low cost.

Description of drawings

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

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

FIG. 3 is a working flowchart of a load state detection circuit provided by an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

It should be noted that the terms "first", "second" and the like in the description, 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 may be implemented independently, or may be implemented in combination with each other, which are not specifically limited in the embodiments of the present invention.

FIG. 1 is a structural diagram of a load state detection circuit provided by an embodiment of the present invention.

As shown in FIG. 1 , the load state detection circuit is applied to electronic equipment, including 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 .

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 detected value to the control unit 10; the constant current source 30 is electrically connected to the external interface 60, and the constant current The flow source 30 is used to provide 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 the internal circuit with the external interface according to the control signal. 60 is connected or disconnected; 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 for controlling the constant current source 30 and the load on-off unit 50 to work through the switch control unit 40 .

Specifically, the voltage detection unit 20 can adjust and obtain the voltage on the external interface 60, and transmit the obtained voltage value (ie, the above-mentioned detection value) to the control unit 10, so as to realize the voltage detection on the external interface 60; the so-called "conditioning" ", which means that the voltage detection unit 20 is provided with a triode and a power supply (ie, the triode in the fourth switch tube, the triode in the fifth switch tube, and the third power supply), and the triode can be used when the voltage of the external interface 60 is too high. When the voltage value output by the voltage detection unit 20 to the control unit 10 is controlled not to exceed the voltage value of the third power supply, the protection of the acquisition pin of the control unit 10 is realized.

The control unit 10 can enable and control 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, so as to protect the electronic device from detecting the load connected to the external interface 60 from not being detected. If damaged, the control unit 10 can also judge 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, etc. The control unit 10 can be composed of a single chip microcomputer, a CPU, a PLC, etc. , can have an ADC (Analog-to-Digital Converter) detection function that outputs a control signal and a voltage signal; and can report the judged load status information to other electronic units or display screens (not shown in FIG. 1 ) connected to the control unit 10 to remind the user that there is an error for timely correction.

The constant current source 30 is used to provide a constant current to the load at the external interface 60. When the load state detection is performed, 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. The constant current source 30 is provided, so after disconnecting from the internal circuit, the voltage value, ie the above-mentioned detection value, can still be detected on the load, thereby realizing the protection of the electronic equipment when the external interface 60 is detected.

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 , it can control the on-and-off of the load on-off unit 50 based on the received control signal. off. 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 perform the action of disconnecting the external interface 60 from the load when an overvoltage fault occurs in the load. The load on-off unit 50 also On-off control of the load can be realized based on the control of the switch control unit 40 .

In the embodiment of the present invention, when the state of the load is detected, the connection between the load and the internal circuit of the electronic device is disconnected, and a constant current source is applied to the load to analyze the voltage information of the external interface connected to the load, and determine The state information of the load is obtained, so that the internal circuit of the electronic device connected to the external interface can be protected, and 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 in the prior art. It can not only protect the electronic equipment from damage, but also can accurately and efficiently detect the external interface status of the electronic equipment online in real time, and has the technical effect of small size and low cost.

FIG. 2 is a circuit diagram of a load state detection circuit provided by an embodiment of the present invention.

Optionally, as shown in FIG. 2 , the constant current source 30 includes a first power supply VCC1, a first resistor R1, a second resistor R2, a first transistor Q1, a second transistor Q2 and a first diode D1 .

The first end of the first resistor R1 is electrically connected to the first power supply VCC1, 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 The VCC1 is electrically connected, the collector of the first transistor Q1 is electrically connected to the first terminal of the second resistor R2 ; the second terminal of the second resistor R2 is electrically connected to the switch control unit 40 .

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, and the collector of the second transistor Q2 The electrode 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 .

Specifically, the constant current source 30 is exemplarily composed of a first power supply VCC1 through a first resistor R1, a first transistor Q1, a second transistor Q2, a second resistor R2 and a first diode D2, see FIG. 2. Taking the first transistor Q1 and the second transistor Q2 as an example of PNP type transistors, since the voltage drop between the base and the emitter of the first transistor Q1 is greater than about 0.7V, the The diode Q2 is turned off to realize constant current, and 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 .

Optionally, as shown in FIG. 2 , the switch control unit 40 includes a first switch transistor Q3 , a second switch transistor Q4 , a third switch transistor Q5 , a second diode D2 and a third diode D3 .

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 of the second switch tube Q4 The terminal is electrically connected to the control unit 10, the first terminal of the second switch tube Q4 is electrically connected to the negative electrode SPK_O_N of the external interface 60, the second terminal of the second switch tube Q4 is grounded; the control terminal of the third switch tube Q5 is connected to the control unit 10 Electrical connection, the first end of the third switch tube Q5 is electrically connected to the load on-off 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 It is electrically connected to the control terminal of the third switch tube Q5 , the anode of the second diode D2 is electrically connected to the anode SPK_O_P of the external interface 60 , and the anode of the third diode D3 is electrically connected to the cathode SPK_O_N of the external interface 60 .

Optionally, as shown in FIG. 2 , the first switch transistor Q3 includes a sixth transistor q1, an eighth resistor r1 and a ninth resistor r2; the second switch transistor Q4 includes a seventh transistor q2 and a tenth resistor r3 and the eleventh resistor r4; the third switch tube includes the eighth transistor q3, the twelfth resistor r5 and the thirteenth resistor r6;

The collector of the sixth transistor q1 is the first end of the first switch transistor Q3, the emitter of the sixth transistor q1 is the second end of the first switch transistor Q3, and the eighth resistor r1 is connected to the sixth transistor Between the emitter and the base of q1, the first end of the ninth resistor r2 is electrically connected to the base of the sixth transistor q1, and the second end of the ninth resistor r2 is the control end of the first switch tube Q3;

The collector of the seventh transistor q2 is the first end of the second switch transistor Q4, the emitter of the seventh transistor q2 is the second end of the second switch transistor Q4, and the tenth resistor r3 is connected to the seventh transistor Between the emitter and the base of q2, the first end of the eleventh resistor r4 is electrically connected to the base of the seventh transistor q2, and the second end of the eleventh resistor r4 is the control end of the second switch transistor Q4 ;

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

Optionally, as shown in FIG. 2 , the switch control unit 40 further includes a fourth diode D4 , a third resistor R3 , a fourth resistor R4 and a fifth resistor R5 .

The anode of the fourth diode D4 is electrically connected to the control unit 10 , the cathode of the fourth diode D4 is electrically connected to the control terminal of the third switch tube Q5 ; the first terminal of the third resistor R3 is electrically connected to the constant current source 30 , the second end of the third resistor R3 is electrically connected to the positive electrode 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 external The negative electrode SPK_O_N of the interface 60 is electrically connected; 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 respectively connected to the negative electrode of the second diode D2, the third The negative electrode of the pole tube D3 is electrically connected.

2, when the output signal SPK_DET_EN of the control unit 10 is set to a high level, the first switch transistor Q3, the second switch transistor Q4 and the third switch transistor Q5 are saturated and conductive between the collector and the emitter , the constant current source 30 flows to the load at the positive pole SPK_O_P of the external interface 60 through the third resistor R3, and then flows through the load at the negative pole SPK_O_N of the external interface 60 and the fourth resistor R4 to the collector of the second switch tube Q4, and finally flows into Ground terminal GND. When an overvoltage fault occurs at the external interface 60, the second diode D2 and the third diode D3 conduct forward, and the collector and the emitter of the third switch transistor Q5 are turned on through the fifth resistor R5, and the load The third transistor Q6 in the on-off unit 50 is turned off, and at the same time, the collector and the emitter of the fourth transistor Q7 and the fifth transistor Q8 in the load on-off unit 50 are turned on, so that the load is turned on. 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 off unit 50 are all turned off, so that the load on-off unit 50 is turned off, and the external interface 60 is connected to the The load is disconnected.

Optionally, as shown in FIG. 2 , the load switching unit 50 includes a second power supply VCC2, a sixth resistor R6, a seventh resistor R7, a third transistor Q6, a fourth transistor Q7, and a fifth transistor. Q8, 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.

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 seventh resistor The second end of 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 are electrically connected.

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. The electrodes are electrically connected to the source of the third field effect transistor Q11 and the source of the fourth field effect transistor Q12.

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, and the drain of the first field effect transistor Q9 is electrically connected to the negative electrode SPK_N of the input interface , the drain of the second field effect transistor Q10 is electrically connected to the negative electrode SPK_O_N of the external interface 60 .

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, and the drain of the third field effect transistor Q11 is electrically connected to the positive electrode SPK_P of the input interface , the drain of the fourth field effect transistor Q12 is electrically connected to the positive electrode SPK_O_P of the external interface 60 .

Specifically, the second power supply VCC2 can drive the first field effect transistor Q9 and the second field effect transistor Q9 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. When the effect transistor Q10 is turned on and off, VCC1 can drive the third field effect transistor Q11 through the totem pole drive circuit composed of the sixth resistor R6, the seventh resistor R7, the third transistor Q6, and the fifth transistor Q8. , the fourth field effect transistor Q12 is turned on and off; and the connection and disconnection of the external interface 60 and the load are further realized.

Optionally, the load on-off unit 50 further includes a first voltage regulator D5 and a second voltage regulator D6; the negative electrode of the first voltage regulator D5 and the gate of the first field effect transistor Q9 and the second field effect transistor Q10 The gate of the first voltage regulator D6 is electrically connected to the source of the first field effect transistor Q9 and the source of the second field effect transistor Q10; the negative electrode of the second voltage regulator D6 is electrically connected to the third field effect transistor The gate of the transistor Q11 and the gate of the fourth field effect transistor Q12 are electrically connected, and the anode of the second voltage regulator D6 is electrically connected to the source of the third field effect transistor Q11 and the source of the fourth field effect transistor Q12.

Specifically, the first voltage regulator D5 is used to prevent the gate-source voltage of the first field effect transistor Q9 and the second field effect transistor Q10 from being too high, thereby protecting the first field effect transistor Q9 and the second field effect transistor Q10 will not be damaged due to overvoltage; the second voltage regulator D6 is used to prevent the gate-source voltage of the third field effect transistor Q11 and the fourth field effect transistor Q12 from being too high, thereby protecting the first field effect transistor Q11 and the fourth FET Q12 will not be damaged due to overvoltage.

Optionally, as shown in FIG. 2 , 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. It is 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, and the third end of the fifth switch tube Q14 is electrically connected to the control unit 10. One end 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 .

Optionally, the fourth switch transistor Q13 includes a ninth transistor q4, a fourteenth resistor r7 and a fifteenth resistor r8; the fifth switch transistor Q14 includes a thirteenth transistor q5, a sixteenth resistor r9 and a tenth resistor Seven resistors r10;

The collector of the ninth transistor q4 is the first end of the fourth switch transistor Q13, the emitter of the ninth transistor q4 is the second end of the fourth switch transistor Q13, and the fourteenth resistor r7 is connected to the ninth transistor Between the emitter and the base of the tube 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 controlled by the fourth switch tube Q13 end.

The collector of the thirteenth transistor q5 is the first end of the fifth switch transistor Q14, the emitter of the thirteenth transistor q5 is the second end of the fifth switch transistor Q14, and the sixteenth resistor r9 is connected to the thirteenth pole Between the emitter and the base of the tube q5, the first end of the seventeenth resistor r10 is electrically connected to the base of the thirteenth tube q5, and the second end of the seventeenth resistor r10 is controlled by the fifth switch tube Q14 end.

Specifically, the second end of the fourth switch Q13 is electrically connected to the negative sampling terminal SPK_ADC_N of the control unit 10 , and the second end of the fifth switch Q14 is electrically connected to the positive sampling terminal SPK_ADC_P of the control unit 10 . The voltage detection unit 20 can realize that the positive and negative sampling terminals of the control unit 10 will not collect the voltage of the external interface 60 because the voltage of the external interface 60 is too high through the control of the transistors in the fourth switch transistor Q13 and the fifth switch transistor Q14. Specifically, when the voltage at the external interface 60 is too high, the transistors in the fourth switch Q13 and the fifth switch Q14 are turned off, and the voltage values obtained by the positive and negative sampling terminals of the control unit 10 The maximum value is the value of the third power supply VCC3. When the magnitude of 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.

FIG. 3 is a working flowchart of a load state detection circuit provided by an embodiment of the present invention.

The working process of the above-mentioned load state detection circuit will be described in detail below with a specific embodiment. As shown in Figure 3, the working process of the load state detection circuit includes the following steps:

In step S301, it is detected whether the external interface is under overvoltage, and if the determination result is yes, then step S302 is performed; otherwise, step S303 is performed.

In step S302, the load on-off unit 50 automatically disconnects the connection between the external interface 60 and the internal circuit of the electronic device.

Step S303, the control unit 10 disconnects the connection between the external interface 60 and the internal circuit of the electronic device.

In step S304, the current source 30 is turned on.

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 .

Step S306, the control unit 10 determines the state of the external interface 60 based on the received voltage value.

Specifically, referring to FIG. 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 about (0.7/R1)*R4+0.3, the positive sampling When the voltage value collected by the terminal SPK_ADC_P is about (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 positive sampling terminal When the voltage value collected by SPK_ADC_P is equal to the voltage value collected by the negative sampling terminal SPK_ADC_N, and is about (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) Positive When the voltage value collected by the positive sampling terminal SPK_ADC_P is about 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 the positive SPK_O_P and negative SPK_O_N interfaces of the external interface 60. (4) When the voltage value collected by the positive sampling terminal SPK_ADC_P is about VCC3, and the voltage value collected 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 (5) When the voltage value collected by the positive sampling terminal SPK_ADC_P is about VCC2-0.7-0.3-0.3, and the voltage collected 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, The load is disconnected.

(6) When the positive SPK_O_P or negative 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 conduct forward, and the third switching tube Q5 is driven through the fifth resistor R5 to saturate and conduct , turn 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. 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 about VCC3, and the control unit 10 sets the SPK_DET_EN signal to a low level to turn off the second switch tube Q4, Avoid damage to the fourth resistor R4 and the second switch tube Q4.

(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 about 0V, at this time The control unit 10 sets the SPK_DET_EN signal to a high level, and 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.

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 connection and disconnection between the external interface 60 and the load by controlling the load on-off unit 50, and report the judgment result to the control unit at the same time. 10 Other electronic units or display screens connected to it to alert the user of errors so that they can be corrected in time.

An embodiment of the present invention further provides an electronic device, where the electronic device includes the load state detection circuit described in any of the foregoing embodiments.

The electronic device provided by the embodiment of the present invention includes the load state detection circuit in the above-mentioned embodiment. Therefore, the electronic device provided by the embodiment of the present invention also has the beneficial effects described in the above-mentioned embodiment, which is not repeated here.

In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection, or It can be connected in one piece; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

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

Claims (10)

1. A load state detection circuit, applied to electronic equipment, is characterized in that, 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 electrically connected with the external interface of the electronic device and the control unit, and is used for detecting the voltage at the external interface and outputting the detected 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 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 the load on-off unit 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, so as to control the operation of the constant current source and the load on-off unit through the switch control unit. 2. The detection circuit according to claim 1, wherein the constant current source comprises a first power supply, a first resistor, a second resistor, a first transistor, a second transistor and a first diode Tube; 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 triode; the emission of the first triode The electrode is electrically connected to the first power supply, 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 triode is electrically connected to the second end of the first resistor, the base of the second triode is electrically connected to the first end of the second resistor, and the second The collector of the triode 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, wherein the switch control unit comprises a first switch transistor, a second switch transistor, a third switch transistor, 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 terminal of the third switch tube, and the anode of the second diode is electrically connected to the anode of the external interface. connected, the anode of the third diode is electrically connected to the cathode of the external interface. 4. The detection circuit according to claim 3, wherein the switch control unit further comprises 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 terminal of the third switch tube; The first end of the third resistor is electrically connected to the constant current source, and the 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 respectively connected to the cathode of the second diode and the third diode negative electrical connection. 5 . The detection circuit according to claim 1 , wherein the load on-off unit comprises a second power supply, a sixth resistor, a seventh resistor, a third transistor, a fourth transistor, a fifth A pole tube, a first field effect tube, a second field effect tube, a third field effect tube and a fourth field effect tube; The first end of the sixth resistor and the first end of the seventh resistor are both electrically connected to the second power supply, and the second end of the sixth resistor is electrically connected to the collector of the third transistor. connected, the second end of the seventh resistor is electrically connected to the base of the fourth transistor; The emitter of the third triode is electrically connected to the emitter of the fourth triode, the collector of the fourth triode is connected to the source of the first field effect transistor, the second The source electrode of the FET is electrically connected; 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 third transistor is electrically connected. The collector of the five triode 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, and the drain of the first field effect transistor is connected to the input interface. The negative electrode is electrically connected, and the drain electrode 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 all electrically connected to the emitter of the fifth triode, and the drain of the third field effect transistor is connected to the input interface. The positive electrode is electrically connected, and the drain electrode of the fourth field effect transistor is electrically connected to the positive electrode of the external interface. 6. The detection circuit according to claim 5, wherein the load on-off unit further comprises a first voltage regulator tube and a second voltage regulator tube; The negative electrode of the first voltage regulator is electrically connected to the grid of the first field effect transistor and the grid of the second field effect transistor, and the positive electrode of the first voltage regulator is connected to the first field effect transistor. the source of the tube and the source of the second field effect tube are electrically connected; The negative electrode of the second voltage regulator is electrically connected to the grid of the third field effect transistor and the grid of the fourth field effect transistor, and the positive electrode of the second voltage regulator is electrically connected to the third field effect transistor The source of the tube and the source of the fourth field effect tube are electrically connected. 7. The detection circuit according to claim 1, wherein the voltage detection unit comprises a third power supply, a fourth switch tube and a fifth switch tube; The control terminal of the fourth switch tube and the control terminal of the fifth switch tube are both electrically connected to the third power supply, and the first end of the fourth switch tube is electrically connected to the negative pole of the external interface, so 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 pole of the external interface, and the second end of the fifth switch tube is electrically connected to the The control unit is electrically connected. 8. The detection circuit according to claim 3, wherein the first switch tube comprises a sixth transistor, an eighth resistor and a ninth resistor; the second switch tube comprises a seventh transistor, The tenth resistor and the eleventh resistor; the third switch tube includes an eighth transistor, a twelfth resistor and a thirteenth resistor; The collector of the sixth transistor is the first end of the first switch, the emitter of the sixth transistor is the second end of the first switch, and the eighth resistor is connected to 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 transistor is the first end of the second switch, the emitter of the seventh transistor is the second end of the second switch, and the tenth resistor is connected to 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 electrically connected 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, and the twelfth resistor is connected to 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 electrically connected to the base of the eighth transistor. The terminal is the control terminal of the third switch tube. 9 . The detection circuit according to claim 7 , wherein the fourth switch tube comprises a ninth transistor, a fourteenth resistor and a fifteenth resistor; the fifth switch tube comprises a thirteenth pole tube, sixteenth resistor and seventeenth resistor; The collector of the ninth transistor is the first end of the fourth switch, the emitter of the ninth transistor is the second end of the fourth switch, and the fourteenth resistor is connected to Between the emitter and the base of the ninth transistor, the first end of the fifteenth resistor is electrically connected to the base of the ninth transistor, and the second end of the fifteenth resistor is electrically connected to the base of the ninth transistor. The terminal is the control terminal of the fourth switch tube; The collector of the thirteenth tube is the first end of the fifth switch tube, the emitter of the thirteenth tube is the second end of the fifth switch tube, and the sixteenth resistor is connected to Between the emitter and the base of the thirteenth tube, the first end of the seventeenth resistor is electrically connected to the base of the thirteenth tube, and the second end of the seventeenth resistor is electrically connected to the base of the thirteenth tube. The terminal is the control terminal of the fifth switch tube. 10 . An electronic device, characterized in that, the electronic device comprises the load state detection circuit according to any one of the preceding claims 1 to 9 . 11 .

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