Overcurrent protection circuit and overcurrent protection system

Abstract

The present application relates to an overcurrent protection circuit and an overcurrent protection system; the overcurrent protection circuit includes a load driving circuit, an overcurrent feedback circuit and a logic gate circuit; the load driving circuit is connected to the load and is used to drive the load based on a load control signal; the overcurrent feedback circuit is connected to the load driving circuit and is used to compare the operating voltage of the load driving circuit with a reference voltage to generate an overcurrent control signal; the first input end of the logic gate circuit is connected to the load driving signal, the second input end of the logic gate circuit is connected to the overcurrent feedback circuit, and the output end of the logic gate circuit is connected to the load driving circuit, and is used to generate a load control signal according to the load driving signal and the overcurrent control signal, and transmit the load control signal to the load driving circuit; the load driving circuit can be reliably and timely turned on or off, and thus when the operating voltage of the load driving circuit is abnormal, the risk of load overcurrent damage can be effectively avoided, thereby improving the reliability of the vehicle-mounted camera.

Description

Technical Field

[0001] The present application relates to the technical field of overcurrent protection, and in particular to an overcurrent protection circuit and an overcurrent protection system. Background Art

[0002] With the continuous development of automobile intelligence, higher requirements are placed on driving safety. On-board cameras have become an indispensable part of ensuring driving safety. The reliability of on-board cameras directly affects driving safety.

[0003] In the prior art, most cars use heated camera modules, i.e., car cameras with lenses equipped with heating wires. By adding sampling resistors on the periphery of the driver chip, the working current of the heating wires can be detected in real time to detect abnormalities in the working current of the car camera. However, in actual applications, only the working current can be detected through the sampling resistors, and it cannot be ensured that the car camera can completely avoid the risk of overcurrent damage. That is, the reliability of the car camera in the prior art is poor.

[0004] There is currently no effective solution to the problem of poor reliability of vehicle-mounted cameras in the prior art. Utility Model Content

[0005] Based on this, it is necessary to provide an overcurrent protection circuit and an overcurrent protection system to address the above technical problems.

[0006] In a first aspect, the present application provides an overcurrent protection circuit, including a load driving circuit, an overcurrent feedback circuit, and a logic gate circuit;

[0007] The load driving circuit is connected to the load and is used to drive the load based on the load control signal;

[0008] The overcurrent feedback circuit is connected to the load driving circuit and is used to compare the operating voltage of the load driving circuit with the reference voltage to generate an overcurrent control signal;

[0009] The first input end of the logic gate circuit is connected to the load driving signal, the second input end of the logic gate circuit is connected to the overcurrent feedback circuit, and the output end of the logic gate circuit is connected to the load driving circuit, and is used to generate a load control signal according to the load driving signal and the overcurrent control signal, and transmit the load control signal to the load driving circuit.

[0010] In one of the embodiments, the overcurrent feedback circuit includes a comparison circuit;

[0011] The inverting input terminal of the comparison circuit is connected to the load driving circuit, the non-inverting input terminal of the comparison circuit is connected to the reference voltage, and the output terminal of the comparison circuit is connected to the second input terminal of the logic gate circuit, so as to compare the operating voltage of the load driving circuit with the reference voltage and generate an overcurrent control signal.

[0012] In one embodiment, the comparison circuit includes a first comparator, a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor;

[0013] One end of the first resistor is connected to the load driving circuit, and the other end of the first resistor is connected to the inverting input end of the first comparator;

[0014] One end of the second resistor is connected to the inverting input end of the first comparator, and the other end of the second resistor is connected to the output end of the first comparator;

[0015] One end of the third resistor is connected to the non-inverting input end of the first comparator, and the other end of the third resistor is grounded;

[0016] One end of the fourth resistor is connected to a connection point between the third resistor and the non-inverting input terminal of the first comparator, and the other end of the fourth resistor is connected to an external power supply;

[0017] One end of the fifth resistor is connected to the output end of the first comparator, and the other end of the fifth resistor is connected to an external power supply;

[0018] The output terminal of the first comparator is connected to the second input terminal of the logic gate circuit.

[0019] In one embodiment, the comparison circuit is a hysteresis comparison circuit.

[0020] In one embodiment, the hysteresis comparison circuit includes a second comparator, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor;

[0021] The inverting input terminal of the second comparator is connected to the load driving circuit; the output terminal of the second comparator is connected to the second input terminal of the logic gate circuit;

[0022] One end of the sixth resistor is connected to the non-inverting input end of the second comparator, and the other end of the sixth resistor is connected to the output end of the second comparator;

[0023] One end of the seventh resistor is connected to the non-inverting input end of the second comparator, and the other end of the seventh resistor is grounded;

[0024] One end of the eighth resistor is connected to the non-inverting input end of the second comparator, and the other end of the eighth resistor is connected to an external power supply;

[0025] One end of the ninth resistor is connected to the output end of the second comparator, and the other end of the ninth resistor is connected to the external power supply.

[0026] In one embodiment, the logic gate circuit includes an AND gate circuit;

[0027] The first input end of the AND gate circuit is connected to a load driving signal, the second input end of the AND gate circuit is connected to an overcurrent feedback circuit, and the output end of the AND gate circuit is connected to a load driving circuit.

[0028] In one embodiment, the load driving circuit includes a driving chip, a switch tube and an inductor;

[0029] The driver chip is connected to a logic gate circuit for turning on or off the driver chip based on a load control signal;

[0030] The first end of the switch tube is connected to the load via the inductor, the second end of the switch tube is connected to the driver chip, and the third end of the switch tube is connected to the overcurrent feedback circuit; when the driver chip is turned on, the drive load works normally; when the driver chip is turned off, the drive load stops working.

[0031] In one embodiment, the switch tube is a MOS tube;

[0032] The drain of the MOS tube is connected to the load via the inductor, the gate of the MOS tube is connected to the driving chip, and the source of the MOS tube is connected to an overcurrent feedback circuit.

[0033] In one embodiment, the overcurrent protection circuit further includes a sampling circuit; the sampling circuit includes a tenth resistor and an eleventh resistor;

[0034] One end of the tenth resistor is connected to the load driving circuit and the overcurrent feedback circuit respectively, and the other end of the tenth resistor is connected to one end of the eleventh resistor;

[0035] The other end of the eleventh resistor is grounded; and a connection point between the eleventh resistor and the tenth resistor is connected to the load driving circuit.

[0036] In a second aspect, the present application further provides an overcurrent protection system, the overcurrent protection system comprising a load, an external power supply, and the overcurrent protection circuit described in any embodiment of the first aspect above;

[0037] The load is connected to the overcurrent protection circuit;

[0038] The external power supply is connected to the load and the overcurrent protection circuit respectively.

[0039] The above-mentioned overcurrent protection circuit and overcurrent protection system, the overcurrent protection circuit includes a load driving circuit, an overcurrent feedback circuit and a logic gate circuit; wherein the load driving circuit is connected to the load and is used to drive the load based on a load control signal; the overcurrent feedback circuit is connected to the load driving circuit and is used to compare the operating voltage of the load driving circuit with a reference voltage to generate an overcurrent control signal; the first input end of the logic gate circuit is connected to the load driving signal, the second input end of the logic gate circuit is connected to the overcurrent feedback circuit, and the output end of the logic gate circuit is connected to the load driving circuit, and is used to generate a load control signal according to the load driving signal and the overcurrent control signal, and transmit the load control signal to the load driving circuit; based on this, the load driving circuit can be reliably and timely turned on or off, and then when the operating voltage of the load driving circuit is abnormal, the risk of load overcurrent damage can be effectively avoided, thereby improving the reliability of the vehicle-mounted camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 is an overall structural diagram of an overcurrent protection circuit in one embodiment;

[0042] Figure 2 is a circuit schematic diagram of a comparison circuit in the first embodiment;

[0043] Figure 3 is a circuit schematic diagram of a comparison circuit in the second embodiment;

[0044] Figure 4 is a simulation circuit diagram of a hysteresis comparison circuit in the second embodiment;

[0045] Figure 5 is a simulation circuit diagram of a hysteresis comparison circuit in the second embodiment;

[0046] Figure 6 It is a schematic diagram of the hysteresis interval in the second embodiment;

[0047] Figure 7 is a circuit schematic diagram of the overcurrent protection circuit in the first embodiment;

[0048] Figure 8 is a circuit schematic diagram of an overcurrent protection circuit in a second embodiment;

[0049] Fig. 9 The figure is a working logic diagram of an overcurrent protection circuit in a specific embodiment.

[0050] Description of reference numerals:

[0051] 100. Load driving circuit; 200. Overcurrent feedback circuit; 300. Logic gate circuit; 210. Comparison circuit; 400. Sampling circuit. DETAILED DESCRIPTION

[0052] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0054] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0055] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0056] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0057] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0058] In one embodiment, Figure 1 As shown, Figure 1 1 is an overall structural diagram of an overcurrent protection circuit in an embodiment; the overcurrent protection circuit includes a load driving circuit 100, an overcurrent feedback circuit 200 and a logic gate circuit 300;

[0059] The load driving circuit 100 is connected to the load and is used to drive the load based on the load control signal;

[0060] The overcurrent feedback circuit 200 is connected to the load driving circuit 100 and is used to compare the operating voltage of the load driving circuit 100 with the reference voltage to generate an overcurrent control signal;

[0061] The first input end of the logic gate circuit 300 is connected to the load driving signal, the second input end of the logic gate circuit 300 is connected to the overcurrent feedback circuit 200, and the output end of the logic gate circuit 300 is connected to the load driving circuit 100, and is used to generate a load control signal according to the load driving signal and the overcurrent control signal, and transmit the load control signal to the load driving circuit 100.

[0062] Among them, the load driving circuit 100 is used to drive the load based on the load control signal; the load control signal is used to turn on or off the load driving circuit 100; when the load driving circuit 100 is turned on, the load is driven to work through the load driving circuit 100; when the load driving circuit 100 is turned off, the load is stopped from driving the load; the load control signal can be but is not limited to a PWM signal, which is not specifically limited here; the load is a heating wire in the vehicle-mounted camera; it should be noted that the load, i.e. the heating wire, can be but is not limited to being connected to the load driving circuit 100 through a flexible printed circuit, which is not specifically limited here.

[0063] Among them, the overcurrent feedback circuit 200 is provided with a reference voltage, which is used to compare the working voltage of the load driving circuit 100 with the reference voltage to generate an overcurrent control signal; it can be understood that the reference voltage is the critical voltage of the working voltage of the load driving circuit 100, which lays the foundation for protecting the load driving circuit 100 from overcurrent damage; the specific voltage value of the reference voltage needs to be set according to the working performance of the load driving circuit 100, and is not specifically limited here; the overcurrent control signal is a high-level signal or a low-level signal, which is used to characterize whether the working voltage of the load driving circuit 100 exceeds the reference voltage; for example, if the working voltage of the load driving circuit 100 is greater than or equal to the reference voltage, the overcurrent control signal is a low-level signal; if the working voltage of the load driving circuit 100 is less than the reference voltage, the overcurrent control signal is a high-level signal.

[0064] Among them, the logic gate circuit 300 is used to generate a load control signal according to the load drive signal and the overcurrent control signal, and transmit the load control signal to the load drive circuit 100; it should be noted that the logic gate circuit 300 can be but is not limited to a combination of an AND gate circuit, a NOT gate circuit, an OR gate circuit or other logic gate circuits, which is not specifically limited here; among them, the load drive signal can be but is not limited to a PWM signal output by the vehicle camera main control chip, which is not specifically limited here.

[0065] Specifically, after the load driving circuit 100 starts working, the overcurrent feedback circuit 200 continuously compares the operating voltage of the load driving circuit 100 with the reference voltage and generates a corresponding overcurrent control signal; when the operating voltage of the load driving circuit 100 is less than the reference voltage, the overcurrent feedback circuit 200 generates an overcurrent control signal, i.e., a high-level signal; the overcurrent control signal, i.e., the high-level signal, is transmitted to the logic gate circuit 300, and the logic gate circuit 300 generates a load control signal according to the load driving signal and the overcurrent control signal, i.e., the high-level signal. At this time, the load control signal can ensure that the load driving circuit 100 Drive the load normally; as the operating voltage of the load driving circuit 100 increases, when the operating voltage of the load driving circuit 100 is greater than or equal to the reference voltage, the overcurrent feedback circuit 200 adjusts the overcurrent control signal from a high level signal to a low level signal, and transmits the overcurrent control signal, i.e., the low level signal, to the logic gate circuit 300. The logic gate circuit 300 generates a load control signal according to the load driving signal and the overcurrent control signal, i.e., the low level signal. At this time, the load driving circuit 100 is turned off by the load control signal, so that the load driving circuit 100 stops driving the load, thereby realizing overcurrent protection of the load.

[0066] In this embodiment, based on the overcurrent feedback circuit 200, it is possible to compare in real time whether the operating voltage of the load driving circuit 100 exceeds the reference voltage, and generate a corresponding overcurrent control signal to be transmitted to the logic gate circuit 300; then based on the logic gate circuit 300, a corresponding load control signal is generated according to the load driving signal and the overcurrent control signal, and based on the load control signal, the load driving circuit 100 can be reliably and timely turned on or off, thereby effectively avoiding the risk of load overcurrent damage, achieving load overcurrent protection, and improving the reliability of the vehicle-mounted camera.

[0067] In one embodiment, the overcurrent feedback circuit 200 includes a comparison circuit;

[0068] The inverting input terminal of the comparison circuit is connected to the load driving circuit 100, the non-inverting input terminal of the comparison circuit is connected to the reference voltage, and the output terminal of the comparison circuit is connected to the second input terminal of the logic gate circuit 300, which is used to compare the operating voltage of the load driving circuit 100 with the reference voltage to generate an overcurrent control signal.

[0069] The comparison circuit includes a comparator, which is used to compare the operating voltage of the load driving circuit 100 connected to the inverting input terminal with the reference voltage connected to the non-inverting input terminal to generate a corresponding overcurrent control signal.

[0070] For example, if the operating voltage of the load driving circuit 100 connected to the inverting input terminal of the comparison circuit is greater than or equal to the reference voltage connected to the non-inverting input terminal of the comparison circuit, the overcurrent control signal output from the output terminal of the comparison circuit is a low-level signal; if the operating voltage of the load driving circuit 100 connected to the inverting input terminal of the comparison circuit is less than the reference voltage connected to the non-inverting input terminal of the comparison circuit, the overcurrent control signal output from the output terminal of the comparison circuit is a high-level signal.

[0071] In this embodiment, based on the comparison circuit, it is possible to accurately determine whether the operating voltage of the load driving circuit 100 connected to the inverting input terminal of the comparison circuit is greater than or equal to the reference voltage connected to the non-inverting input terminal of the comparison circuit. Based on this, the corresponding overcurrent control signal can be accurately generated, laying the foundation for improving the reliability of the vehicle-mounted camera.

[0072] In one embodiment, Figure 2 As shown, Figure 2 210 is a circuit schematic diagram of a comparison circuit in the first embodiment; the comparison circuit 210 includes a first comparator, a first resistor R10, a second resistor R11, a third resistor R13, a fourth resistor R12 and a fifth resistor R14;

[0073] One end of the first resistor R10 is connected to the load driving circuit 100, and the other end of the first resistor R10 is connected to the inverting input end of the first comparator;

[0074] One end of the second resistor R11 is connected to the inverting input terminal of the first comparator, and the other end of the second resistor R11 is connected to the output terminal Vo of the first comparator;

[0075] One end of the third resistor R13 is connected to the non-inverting input end of the first comparator, and the other end of the third resistor R13 is grounded;

[0076] One end of the fourth resistor R12 is connected to a connection point of the third resistor R13 and the non-inverting input terminal of the first comparator, and the other end of the fourth resistor R12 is connected to an external power supply VCC;

[0077] One end of the fifth resistor R14 is connected to the output terminal Vo of the first comparator, and the other end of the fifth resistor R14 is connected to the external power supply VCC;

[0078] The output terminal Vo of the first comparator is connected to the second input terminal of the logic gate circuit 300 .

[0079] Among them, the first resistor R10 and the second resistor R11 are both voltage-dividing resistors, which are used to divide the working voltage of the load driving circuit 100 to obtain the divided voltage Vp, and then compare the divided voltage Vp with the reference voltage Vref to generate a corresponding overcurrent control signal; the third resistor R13 and the fourth resistor R12 are both voltage-dividing resistors; based on the voltage-dividing principle, by adjusting the resistance values ​​of the third resistor R13 and the fourth resistor R12, different reference voltages Vref can be obtained to improve the applicability of the comparison circuit 210. The external power supply VCC is a digital power supply, and the voltage value of the external power supply VCC needs to be set according to the performance of the comparison circuit 210, which is not specifically limited here.

[0080] It should be noted that the resistance values ​​of the first resistor R10, the second resistor R11 and the fifth resistor R14 need to be set according to the performance of the actual comparison circuit 210, and are not specifically limited here; the resistance values ​​of the third resistor R13 and the fourth resistor R12 need to be set according to the performance of the load driving circuit 100, and are not specifically limited here.

[0081] For example, based on the first resistor R10 and the second resistor R11, a voltage Vp is obtained after the divided voltage of the working voltage of the load driving circuit 100, and the divided voltage Vp is compared with the reference voltage Vref; if the divided voltage Vp is greater than or equal to the reference voltage Vref, the overcurrent control signal output by the output terminal Vo of the first comparator is a low-level signal; if the divided voltage Vp is less than the reference voltage Vref, the overcurrent control signal output by the output terminal Vo of the first comparator is a high-level signal.

[0082] In this embodiment, based on the first comparator, the voltage Vp after the working voltage of the load driving circuit 100 is divided is compared with the reference voltage Vref, so that the corresponding overcurrent control signal can be accurately generated; based on the third resistor R13 and the fourth resistor R12, different reference voltages Vref can be flexibly configured, thereby improving the applicability and flexibility of the comparison circuit 210; by adopting a smaller number of discrete components, namely the first comparator, the first resistor R10, the second resistor R11, the third resistor R13, the fourth resistor R12 and the fifth resistor R14, the cost of the comparison circuit 210 can be effectively reduced, and the occupied space of the comparison circuit 210 can be reduced.

[0083] In one embodiment, the comparison circuit 210 is a hysteresis comparison circuit.

[0084] Among them, the hysteresis comparison circuit has a hysteresis function; the hysteresis comparison circuit can generate two different reference voltages during the change of the working voltage of the load driving circuit 100 by introducing a hysteresis loop, so as to reduce the interference of signal noise on the overcurrent control signal, and can effectively avoid the problem of inaccurate overcurrent control signal caused by signal noise interference. It can be understood that the two different reference voltages generated by the hysteresis comparison circuit can constitute a hysteresis interval.

[0085] Preferably, Figure 3 As shown, Figure 3 : is a circuit schematic diagram of the comparison circuit in the second embodiment; the hysteresis comparison circuit includes a second comparator, a sixth resistor R5, a seventh resistor R3, an eighth resistor R2 and a ninth resistor R4;

[0086] The inverting input terminal of the second comparator is connected to the load driving circuit 100; the output terminal Vo of the second comparator is connected to the second input terminal of the logic gate circuit 300;

[0087] One end of the sixth resistor R5 is connected to the non-inverting input terminal of the second comparator, and the other end of the sixth resistor R5 is connected to the output terminal Vo of the second comparator;

[0088] One end of the seventh resistor R3 is connected to the non-inverting input end of the second comparator, and the other end of the seventh resistor R3 is grounded;

[0089] One end of the eighth resistor R2 is connected to the non-inverting input terminal of the second comparator, and the other end of the eighth resistor R2 is connected to the external power supply VCC;

[0090] One end of the ninth resistor R4 is connected to the output terminal Vo of the second comparator, and the other end of the ninth resistor R4 is connected to the external power supply VCC.

[0091] Among them, the seventh resistor R3 and the eighth resistor R2 are both voltage-dividing resistors. By adjusting the resistance values ​​of the sixth resistor R5, the seventh resistor R3 and the eighth resistor R2, different reference voltages Vref can be obtained. It should be noted that the resistance values ​​of the sixth resistor R5, the seventh resistor R3, the eighth resistor R2 and the ninth resistor R4 need to be set according to the performance of the hysteresis comparison circuit and the load driving circuit 100, and are not specifically limited here. The external power supply VCC is a digital power supply, and the voltage value of the external power supply VCC needs to be set according to the performance of the hysteresis comparison circuit, and is not specifically limited here.

[0092] For example, it is assumed that the operating voltage of the load driving circuit 100 is Vi; and it is assumed that the two reference voltages Vref corresponding to the hysteresis interval of the hysteresis comparison circuit are V TH and V TL , where V TH is the overcurrent protection reference voltage, V TL It is understood that if the current overcurrent control signal is a high-level signal, as the operating voltage of the load driving circuit 100 increases, when the operating voltage of the load driving circuit 100 is greater than or equal to the overcurrent protection reference voltage, that is, Vi≥V TH When the overcurrent control signal output by the output terminal Vo of the second comparator is a low level signal; if the current overcurrent control signal is a low level signal, as the working voltage of the load driving circuit 100 decreases, when the working voltage of the load driving circuit 100 is less than the protection release reference voltage, that is, Vi <V TL When , the overcurrent control signal output by the output terminal Vo of the second comparator is a high level signal; based on this, the interference of signal noise on the overcurrent control signal can be effectively reduced.

[0093] Furthermore, based on Kirchhoff's current law, the overcurrent protection reference voltage V can be calculated. TH And the protection release reference voltage V TL Specifically, when the overcurrent control signal generated by the output terminal Vo of the second comparator is a low-level signal, if the operating voltage Vi of the load driving circuit 100 is equal to the reference voltage Vref, the overcurrent protection reference voltage V can be obtained based on Kirchhoff's current law. TH , the specific calculation process is shown in formula (1)-(2).

[0094]

[0095]

[0096] Among them, R5 is the sixth resistor; R3 is the seventh resistor; R2 is the eighth resistor; R4 is the ninth resistor; and VCC is the external power supply.

[0097] When the overcurrent control signal generated by the output terminal Vo of the second comparator is a high level signal, if the operating voltage Vi of the load driving circuit 100 is equal to the reference voltage Vref, the overcurrent protection reference voltage V can be obtained based on Kirchhoff's current law. TL , the specific calculation process is shown in formulas (3)-(4).

[0098]

[0099]

[0100] Among them, R5 is the sixth resistor; R3 is the seventh resistor; R2 is the eighth resistor; R4 is the ninth resistor; and VCC is the external power supply.

[0101] For further information, see Figure 4-Figure 6 , assuming that the external power supply VCC = 3.3V, R2 = 1K, R3 = 1K, R4 = 1K, R5 = 20K, based on formula (2) and formula (4), the overcurrent protection reference voltage V TH About 1.69V, protection release reference voltage V TL When the operating voltage Vi of the load driving circuit 100 is greater than or equal to the overcurrent protection reference voltage V TH , that is, when Vi≥1.69V, the overcurrent control signal output by the output terminal Vo of the second comparator is a low level signal; when the operating voltage Vi of the load driving circuit 100 is less than the protection release reference voltage V TL , that is, when Vi<1.61V, the overcurrent control signal output by the output terminal Vo of the second comparator is a high level signal. It can be understood that based on Ohm's law, according to the overcurrent protection reference voltage V TH And the protection release reference voltage V TL , the corresponding overcurrent protection reference current and protection release reference current can be calculated. The specific calculation process will not be described here.

[0102] In this embodiment, based on the hysteresis function of the hysteresis comparison circuit, the interference of signal noise on the overcurrent control signal can be effectively reduced, thereby effectively avoiding the problem of unreliable overcurrent control signal due to signal noise interference, thereby improving the stability and reliability of the comparison circuit 210, and thereby improving the stability and reliability of the overcurrent protection circuit.

[0103] In one embodiment, see Figure 7 and Figure 8 , the logic gate circuit 300 includes an AND gate circuit;

[0104] The first input terminal of the AND gate circuit is connected to the load driving signal, the second input terminal of the AND gate circuit is connected to the overcurrent feedback circuit 200 , and the output terminal of the AND gate circuit is connected to the load driving circuit 100 .

[0105] The load driving signal may be, but is not limited to, a PWM signal, which is not specifically limited here.

[0106] Specifically, assuming that the load driving signal is a PWM signal, the first input end of the AND gate circuit is connected to the load driving signal, i.e., the PWM signal, and the second input end of the AND gate circuit is connected to the overcurrent control signal, i.e., a high-level signal or a low-level signal. The AND gate circuit generates a load control signal based on the load driving signal, i.e., the PWM signal and the overcurrent control circuit, and transmits it to the load driving circuit 100 to turn on or off the load driving circuit 100; for example, when the overcurrent control signal is a high-level signal, the load control signal will normally turn on or off the load driving circuit 100 along with the load driving signal, i.e., the PWM signal; when the overcurrent control signal is a low-level signal, since the second input end of the AND gate circuit is a low-level signal, the load control signal is also a low-level signal. At this time, the load control signal continuously turns off the load driving circuit 100 to avoid the risk of damage from overcurrent to the load.

[0107] In this embodiment, based on the AND gate circuit, a corresponding load control signal can be generated according to the load drive signal and the overcurrent control circuit to accurately and reliably control the load drive circuit 100 to turn on or off, thereby improving the accuracy and reliability of the overcurrent protection circuit, and further improving the reliability of the vehicle-mounted camera.

[0108] In one embodiment, see Figure 7 and Figure 8 , the load driving circuit 100 includes a driving chip, a switch tube and an inductor;

[0109] The driver chip is connected to the logic gate circuit 300 and is used to turn on or off the driver chip based on the load control signal;

[0110] The first end of the switch tube is connected to the load via the inductor, the second end of the switch tube is connected to the driver chip, and the third end of the switch tube is connected to the overcurrent feedback circuit; it is used to drive the load to work normally when the driver chip is turned on; when the driver chip is turned off, the driver load stops working.

[0111] Preferably, the switch tube is a MOS tube;

[0112] The drain of the MOS tube is connected to the load via the inductor, the gate of the MOS tube is connected to the driving chip, and the source of the MOS tube is connected to the overcurrent feedback circuit 200 .

[0113] Among them, the EN / DIM pin of the driving chip is connected to the logic gate circuit 300, which is used to turn on or off the driving chip based on the load control signal; when the driving chip is turned on, the switching signal is output to the switching tube according to the load control signal; when the driving chip is turned off, the switching signal is stopped from being output; wherein, the switching signal is used to control the switching tube to be turned on or off; for example, when the driving chip is turned on, when the switching signal controls the switching tube to be turned on, the driving load starts to work; when the switching signal controls the switching tube to be turned off, the driving load stops working; the inductor is used for energy storage; it should be noted that the driving chip, the switching tube and the inductor need to be selected according to the actual driving requirements, and no specific limitation is made here.

[0114] Among them, the MOS tube is an N-type MOS tube; when the gate voltage of the MOS tube is greater than the source voltage of the MOS tube, the MOS tube is turned on; when the gate voltage of the MOS tube is less than the source voltage of the MOS tube, the MOS tube is turned off.

[0115] For example, see Figure 7 and Figure 8 The drain of the MOS tube is connected to the load via the inductor, the gate of the MOS tube is connected to the GATE pin of the driver chip, and the source of the MOS tube is connected to the overcurrent feedback circuit 200; wherein, the GATE pin of the driver chip is used to output a switching signal to the MOS tube according to the load control signal when the driver chip is turned on, so as to control the MOS tube to be turned on or off.

[0116] In this embodiment, the driver chip, switch tube and inductor provide the hardware basis for driving the load; based on the load control signal, the driver chip can be turned on or off reliably and accurately to avoid the risk of overcurrent damage to the load, thereby improving the safety and reliability of the load.

[0117] In one embodiment, see Figure 7 and Figure 8 , the overcurrent protection circuit further includes a sampling circuit 400; the sampling circuit 400 includes a tenth resistor R1 and an eleventh resistor Rcs;

[0118] One end of the tenth resistor R1 is connected to the load driving circuit 100 and the overcurrent feedback circuit 200 respectively, and the other end of the tenth resistor R1 is connected to one end of the eleventh resistor Rcs;

[0119] The other end of the eleventh resistor Rcs is grounded; and a connection point between the eleventh resistor Rcs and the tenth resistor R1 is connected to the load driving circuit 100 .

[0120] The tenth resistor R1 and the eleventh resistor Rcs are sampling resistors for determining the operating voltage and the operating current of the load driving circuit 100 .

[0121] For example, one end of the tenth resistor R1 is respectively connected to the third end of the switch tube and the overcurrent feedback circuit 200, and the other end of the tenth resistor R1 is connected to one end of the eleventh resistor Rcs; the other end of the eleventh resistor Rcs is grounded; the connection point between the eleventh resistor Rcs and the tenth resistor R1 is connected to the CS pin of the driving chip; based on the CS pin of the driving chip, the voltage value at the connection point between the eleventh resistor Rcs and the tenth resistor R1 can be collected; further, based on the voltage division principle, according to the voltage values ​​collected by the tenth resistor R1, the eleventh resistor Rcs and the CS pin of the driving chip, the operating voltage Vi of the load driving circuit 100 can be calculated, and the specific calculation process will not be repeated here.

[0122] It should be noted that if the comparison circuit 210 is a hysteresis comparison circuit, based on Ohm's law, according to the sampling circuit 400 and the overcurrent protection reference voltage V TH And the protection release reference voltage V TL , can accurately calculate the corresponding overcurrent protection reference current and protection release reference current; for example, assuming that the overcurrent protection reference voltage V TH About 1.69V, protection release reference voltage V TL About 1.61V, the tenth resistor R1 is equal to 0.6Ω, the eleventh resistor Rcs is equal to 0.2Ω, and it can be calculated that the overcurrent protection reference current is about 2.1125A, the protection release reference current is about 2.0125A, and the current corresponding to the hysteresis interval is 0.1A.

[0123] In this embodiment, based on the sampling circuit 400, the operating voltage Vi of the load driving circuit 100 can be accurately obtained, and when the comparison circuit 210 is a hysteresis comparison circuit, the overcurrent protection reference current and the protection release reference current can be accurately obtained, laying a foundation for improving the reliability of the overcurrent protection circuit.

[0124] In a specific embodiment, the overcurrent feedback circuit 200 may also be connected to the nINT pin or GPIO pin of the vehicle-mounted camera main control chip to be reserved for functional safety error reporting.

[0125] In a specific embodiment, taking the comparison circuit 210 as a hysteresis comparison circuit as an example, the working logic of the overcurrent protection circuit is as follows: Fig. 9 As shown, the specific steps include:

[0126] Step S901: The load driving circuit drives the load normally; the operating voltage Vi of the load driving circuit is compared with the overcurrent protection reference voltage V in real time through the hysteresis comparison circuit. TH .

[0127] Step S902, determining whether the operating voltage Vi of the load driving circuit is greater than or equal to the overcurrent protection reference voltage V TH .

[0128] Specifically, if yes, execute step S903; if no, repeat step S902 until the operating voltage Vi of the load driving circuit is greater than or equal to the overcurrent protection reference voltage V TH , execute step S903.

[0129] Step S903, adjusting the overcurrent control signal through the hysteresis comparison circuit, at this time the overcurrent control signal is a low level signal.

[0130] Step S904: the logic gate circuit generates a load control signal according to the overcurrent control signal, ie, the low level signal, and the load driving signal.

[0131] Step S905: according to the load control signal, the load driving circuit is turned off, and when the working voltage Vi of the load driving circuit drops to the protection release reference voltage V TL Previously, the load driving circuit was always kept off.

[0132] Step S906: When the operating voltage Vi of the load driving circuit drops to less than the protection release reference voltage V TL When the overcurrent control signal is adjusted through the hysteresis comparison circuit, the overcurrent control signal is a high level signal.

[0133] Step S907 : the logic gate circuit generates a load control signal according to the overcurrent control signal, ie, the high level signal, and the load driving signal.

[0134] After step S907 is completed, the process goes to step S901 and the above steps are repeatedly executed to implement overcurrent protection of the load.

[0135] The above-mentioned overcurrent protection circuit, on the one hand, can compare in real time whether the operating voltage of the load driving circuit 100 exceeds the reference voltage based on the overcurrent feedback circuit 200, and generate a corresponding overcurrent control signal to be transmitted to the logic gate circuit 300; then based on the logic gate circuit 300, a corresponding load control signal is generated according to the load driving signal and the overcurrent control signal, and based on the load control signal, the load driving circuit 100 can be reliably and timely turned on or off, thereby effectively avoiding the risk of load overcurrent damage, realizing load overcurrent protection, and improving the reliability of the vehicle-mounted camera. On the second hand, based on the first comparator, the voltage Vp after the load driving circuit 100 working voltage is divided is compared with the reference voltage Vref, and the corresponding overcurrent control signal can be accurately generated; based on the third resistor R13 and the fourth resistor R12, different reference voltages Vref can be flexibly configured, thereby improving the applicability and flexibility of the comparison circuit 210; by using a small number of discrete components, namely the first comparator, the first resistor R10, the second resistor R11, the third resistor R13, the fourth resistor R12 and the fifth resistor R14, the cost of the comparison circuit 210 can be effectively reduced, and the occupied space of the comparison circuit 210 can be reduced. On the third hand, based on the hysteresis function of the hysteresis comparison circuit, the interference of the signal noise on the overcurrent control signal can be effectively reduced, thereby effectively avoiding the problem of unreliable overcurrent control signal caused by signal noise interference, thereby improving the stability and reliability of the comparison circuit 210, thereby improving the stability and reliability of the overcurrent protection circuit. Fourthly, based on the AND gate circuit, a corresponding load control signal can be generated according to the load drive signal and the overcurrent control circuit to accurately and reliably control the load drive circuit 100 to turn on or off, thereby improving the accuracy and reliability of the overcurrent protection circuit, and thus improving the reliability of the vehicle-mounted camera. Fifthly, based on the sampling circuit 400, the operating voltage Vi of the load drive circuit 100 can be accurately obtained, and when the comparison circuit 210 is a hysteresis comparison circuit, the overcurrent protection reference current and the protection release reference current can be accurately obtained, laying a foundation for further improving the reliability of the overcurrent protection circuit.

[0136] In one embodiment, an overcurrent protection system includes a load, an external power supply, and an overcurrent protection circuit in any of the above embodiments;

[0137] The load is connected to the overcurrent protection circuit;

[0138] The external power supply is connected to the load and the overcurrent protection circuit respectively.

[0139] The load is the heating wire in the vehicle camera; it should be noted that the load, i.e. the heating wire, can be connected to the overcurrent protection circuit through a flexible printed circuit, but is not limited to this, and is not specifically limited here. The external power supply is a digital power supply; the external power supply provides working power for the load and the overcurrent protection circuit; the specific voltage value of the external power supply needs to be set according to actual needs, and is not specifically limited here.

[0140] In this embodiment, based on the overcurrent protection circuit, the safety of the load can be ensured, and further the reliability and safety of the overcurrent protection system can be ensured.

[0141] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0142] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0143] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. An overcurrent protection circuit, characterized in that: It includes a load driving circuit, an overcurrent feedback circuit and a logic gate circuit; The load driving circuit is connected to the load and is used to drive the load based on the load control signal; The overcurrent feedback circuit is connected to the load driving circuit and is used to compare the operating voltage of the load driving circuit with the reference voltage to generate an overcurrent control signal; The first input end of the logic gate circuit is connected to the load driving signal, the second input end of the logic gate circuit is connected to the overcurrent feedback circuit, and the output end of the logic gate circuit is connected to the load driving circuit, and is used to generate a load control signal according to the load driving signal and the overcurrent control signal, and transmit the load control signal to the load driving circuit.

2. The overcurrent protection circuit according to claim 1, characterized in that: The overcurrent feedback circuit includes a comparison circuit; The inverting input terminal of the comparison circuit is connected to the load driving circuit, the non-inverting input terminal of the comparison circuit is connected to the reference voltage, and the output terminal of the comparison circuit is connected to the second input terminal of the logic gate circuit, so as to compare the operating voltage of the load driving circuit with the reference voltage and generate an overcurrent control signal.

3. The overcurrent protection circuit according to claim 2, characterized in that: The comparison circuit includes a first comparator, a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor; One end of the first resistor is connected to the load driving circuit, and the other end of the first resistor is connected to the inverting input end of the first comparator; One end of the second resistor is connected to the inverting input end of the first comparator, and the other end of the second resistor is connected to the output end of the first comparator; One end of the third resistor is connected to the non-inverting input end of the first comparator, and the other end of the third resistor is grounded; One end of the fourth resistor is connected to a connection point between the third resistor and the non-inverting input terminal of the first comparator, and the other end of the fourth resistor is connected to an external power supply; One end of the fifth resistor is connected to the output end of the first comparator, and the other end of the fifth resistor is connected to an external power supply; The output terminal of the first comparator is connected to the second input terminal of the logic gate circuit.

4. The overcurrent protection circuit according to claim 2, characterized in that: The comparison circuit is a hysteresis comparison circuit.

5. The overcurrent protection circuit according to claim 4, characterized in that: The hysteresis comparison circuit includes a second comparator, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor; The inverting input terminal of the second comparator is connected to the load driving circuit; the output terminal of the second comparator is connected to the second input terminal of the logic gate circuit; One end of the sixth resistor is connected to the non-inverting input end of the second comparator, and the other end of the sixth resistor is connected to the output end of the second comparator; One end of the seventh resistor is connected to the non-inverting input end of the second comparator, and the other end of the seventh resistor is grounded; One end of the eighth resistor is connected to the non-inverting input end of the second comparator, and the other end of the eighth resistor is connected to an external power supply; One end of the ninth resistor is connected to the output end of the second comparator, and the other end of the ninth resistor is connected to the external power supply.

6. The overcurrent protection circuit according to claim 1, characterized in that: The logic gate circuit includes an AND gate circuit; The first input end of the AND gate circuit is connected to a load driving signal, the second input end of the AND gate circuit is connected to an overcurrent feedback circuit, and the output end of the AND gate circuit is connected to a load driving circuit.

7. The overcurrent protection circuit according to claim 1, characterized in that: The load driving circuit includes a driving chip, a switch tube and an inductor; The driver chip is connected to a logic gate circuit for turning on or off the driver chip based on a load control signal; The first end of the switch tube is connected to the load via the inductor, the second end of the switch tube is connected to the driver chip, and the third end of the switch tube is connected to the overcurrent feedback circuit; when the driver chip is turned on, the drive load works normally; when the driver chip is turned off, the drive load stops working.

8. The overcurrent protection circuit according to claim 7, characterized in that: The switch tube is a MOS tube; The drain of the MOS tube is connected to the load via the inductor, the gate of the MOS tube is connected to the driving chip, and the source of the MOS tube is connected to an overcurrent feedback circuit.

9. The overcurrent protection circuit according to claim 1, characterized in that: The overcurrent protection circuit further includes a sampling circuit; the sampling circuit includes a tenth resistor and an eleventh resistor; One end of the tenth resistor is connected to the load driving circuit and the overcurrent feedback circuit respectively, and the other end of the tenth resistor is connected to one end of the eleventh resistor; The other end of the eleventh resistor is grounded; and a connection point between the eleventh resistor and the tenth resistor is connected to the load driving circuit.

10. An overcurrent protection system, characterized in that: The overcurrent protection system comprises a load, an external power supply and an overcurrent protection circuit according to any one of claims 1 to 9; The load is connected to the overcurrent protection circuit; The external power supply is connected to the load and the overcurrent protection circuit respectively.

Images