Overcurrent signal processing latch circuit and overcurrent protection device

Abstract

The utility model provides an over-current signal processing latch circuit and an over-current protection device, and relates to the technical field of over-current protection. The circuit comprises a signal processing circuit, a voltage comparison circuit and a latch circuit, the output end of the signal processing circuit is connected with the input end of the voltage comparison circuit, and the output end of the voltage comparison circuit is connected with the input end of the latch circuit. The input end of the signal processing circuit and the input end of the latch circuit are used for being connected with the output end of a current detection device, and the output end of the latch circuit is used for being connected with the input end of the driving circuit; the signal processing circuit is used for receiving a current state signal from the current detection device and processing the current state signal to generate an analog signal, the voltage comparison circuit is used for comparing a corresponding voltage value of the analog signal with a preset voltage value to output a corresponding level, and the latch circuit is used for driving the driving circuit according to the level. According to the utility model, processing of over-current signals of different types can be realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to overcurrent protection technical field, specifically, an overcurrent signal processing latch circuit and overcurrent protection device are provided. BACKGROUND

[0002] The overcurrent fault signal latch circuit is an electronic circuit device for detecting, recording and keeping overcurrent state signals, and the overcurrent fault signal latch circuit based on a flip-flop is taken as an example, the latch function of the overcurrent signal in the motor controller can be realized through the data latch function of the flip-flop chip, the trigger signal for triggering the rising edge is generated through the transistor circuit (i.e. the rising edge signal circuit), thereby providing reliable overcurrent protection for the corresponding system and guaranteeing the safe operation of the equipment.

[0003] However, the related overcurrent fault signal latch circuit mostly realizes overcurrent protection through directly detecting the voltage of the current sampling circuit, for example, the arbitrary two-phase current of a three-phase motor controller is sampled, and the current form collected is always high or always low, therefore the related overcurrent fault signal latch circuit can only process the current in the form of always high or always low, and the processing capacity is relatively single. SUMMARY

[0004] The problem solved by the utility model is how to realize the processing of different types of overcurrent signals.

[0005] To solve the above problems, the utility model provides an overcurrent signal processing latch circuit and overcurrent protection device.

[0006] In the first aspect, the utility model provides an overcurrent signal processing latch circuit, including signal processing circuit, voltage comparison circuit and latch circuit, the output of signal processing circuit is connected with the input of voltage comparison circuit, the output of voltage comparison circuit is connected with the input of latch circuit, the input of signal processing circuit and the input of latch circuit are used for connecting with the output of current detection device, the output of latch circuit is used for connecting with the input of drive circuit;

[0007] The signal processing circuit is used for receiving the current state signal from the current detection device, and processing the current state signal to generate an analog signal, the voltage comparison circuit is used for comparing the corresponding voltage value of the analog signal with the preset voltage value to output the corresponding level, and the latch circuit is used for driving the drive circuit according to the level.

[0008] Optionally, the signal processing circuit comprises a first resistor and a first capacitor, one end of the first resistor and one end of the first capacitor are output ends of the signal processing circuit, and are connected to the inverting input end of the voltage comparison circuit, the other end of the first resistor is connected to the current detection device, and the other end of the first capacitor is grounded.

[0009] Optionally, the voltage comparison circuit comprises a voltage comparator and a filter circuit, the inverting input end of the voltage comparator is connected to the output end of the signal processing circuit, the output end of the voltage comparator is connected to the input end of the filter circuit, and the output end of the filter circuit is connected to the input end of the latch circuit.

[0010] Optionally, the filter circuit comprises a third capacitor, a fourth resistor and a fifth resistor, the fifth resistor is connected to the output end of the voltage comparator and the input end of the latch circuit, one end of the third capacitor is connected to a connection line between the fifth resistor and the output end of the voltage comparator, one end of the fourth resistor is connected to a connection line between the fifth resistor and the latch circuit, and the other end of the third capacitor and the other end of the fourth resistor are grounded.

[0011] Optionally, the voltage comparison circuit further comprises a fifteenth resistor, the two ends of the fifteenth resistor are connected to the output end of the voltage comparator and the positive input end of the voltage comparator.

[0012] Optionally, the overcurrent signal processing latch circuit further comprises a sampling circuit, the sampling circuit comprises a ninth resistor and a sixth capacitor, one end of the ninth resistor is connected to the output end of the voltage comparator, the other end of the ninth resistor is connected to one end of the sixth capacitor, a connection point between the ninth resistor and the sixth capacitor is connected to the input end of the controller, and the other end of the sixth capacitor is grounded.

[0013] Optionally, the overcurrent signal processing latch circuit further comprises a voltage dividing circuit, the voltage dividing circuit comprises a second capacitor, a second resistor and a third resistor, one end of the second capacitor, one end of the second resistor and one end of the third resistor are connected to the positive input end of the voltage comparator, the other end of the second resistor is connected to the power supply, and the other end of the second capacitor and the other end of the third resistor are grounded.

[0014] Optionally, the latch circuit comprises a latch, the data input end of the latch is connected to the output end of the voltage comparison circuit, the clock input end of the latch is connected to the output end of the current detection device, and the inverting output end of the latch is connected to the input end of the driving circuit.

[0015] Optionally, the overcurrent signal processing latch circuit further comprises a pull-down circuit, the pull-down circuit comprising a pull-down transistor, a thirteenth resistor and a fourteenth resistor, a drain of the pull-down transistor being connected with an input of the latch, a gate of the pull-down transistor being grounded through the thirteenth resistor, the gate of the pull-down transistor further being used for being connected with an output of a controller through the fourteenth resistor, and a source of the pull-down transistor being grounded.

[0016] In a second aspect, the utility model provides an overcurrent protection device, including current detection device, drive circuit, relay and overcurrent signal processing latch circuit, the input of current detection device is used for connecting with load, the output of current detection device is connected with the input of overcurrent signal processing latch circuit, the output of overcurrent signal processing latch circuit is connected with the input of drive circuit, the output of drive circuit is connected with relay, and relay is used for controlling the on-off of the power supply loop of load, current detection device is used for outputting corresponding current state signal according to the current state of load, overcurrent signal processing latch circuit is used for outputting corresponding level according to current state signal to drive drive circuit to control the switching state of relay.

[0017] The overcurrent signal processing latch circuit of the utility model has the advantages that: after the signal processing circuit processes the current state signals with different duty cycles provided by the current detection device, analog signals are generated, the corresponding voltage values of the analog signals are compared with preset voltage values by the voltage comparison circuit, and the analog signals are converted into level driving signals, so that the drive circuit can control the relays and other devices of the power supply loop according to the level driving signals, for example, the drive circuit can disconnect the relays of the power supply loop to realize rapid overcurrent shutdown and protect the load in time, and therefore the utility model can be compatible with current state signals with different duty cycles, and compared with the technical scheme in the related art which can only process the signals with constant high or constant low, the utility model can process overcurrent signals of different types. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structure block diagram of the overcurrent signal processing latch circuit of the utility model embodiment.

[0019] Figure 2 It is a circuit schematic diagram of the overcurrent signal processing latch circuit of the utility model embodiment.

[0020] Figure 3 It is a truth table corresponding to the input and output signal states of the latch U2 of the utility model embodiment.

[0021] Figure 4 It is a structure block diagram of the overcurrent protection device of the utility model embodiment. DETAILED DESCRIPTION

[0022] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. Although some embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms, and should not be interpreted as being limited to the embodiments described herein, on the contrary, these embodiments are provided to make the present application more thorough and complete. It should be understood that the drawings and embodiments of the present application are only for illustrative purposes, and are not intended to limit the scope of protection of the present application.

[0023] The term "comprising" and variations thereof as used herein are open-ended, that is "including, but not limited to"; the term "based on" is "based, at least in part, on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". Related definitions of other terms will be given in the description below. It should be noted that the "first", "second", etc. concepts mentioned in the present application are only used to distinguish different devices, modules or units, and are not intended to limit the order or interdependence of the functions performed by these devices, modules or units.

[0024] It should be noted that the modification of "one" or "multiple" mentioned in the present application is illustrative and not limiting, and those skilled in the art should understand that unless otherwise explicitly indicated in the context, it should be understood as "one or more".

[0025] As shown in Figure 1 The latch circuit provided by the embodiment of the present application includes a signal processing circuit, a voltage comparison circuit and a latch circuit, the output end of the signal processing circuit is connected with the input end of the voltage comparison circuit, the output end of the voltage comparison circuit is connected with the input end of the latch circuit, the input end of the signal processing circuit and the input end of the latch circuit are used to be connected with the output end of the current detection device, and the output end of the latch circuit is used to be connected with the input end of the driving circuit.

[0026] The signal processing circuit is used to receive the current state signal from the current detection device and process the current state signal to generate an analog signal, the voltage comparison circuit is used to compare the corresponding voltage value of the analog signal with a preset voltage value to output a corresponding level, and the latch circuit is used to drive the driving circuit according to the level.

[0027] Specifically, the overcurrent signal processing latch circuit includes a signal processing circuit, a voltage comparison circuit and a latch circuit, an output end of the signal processing circuit is connected with an input end of the voltage comparison circuit, an output end of the voltage comparison circuit is connected with an input end of the latch circuit, an input end of the signal processing circuit and an input end of the latch circuit are used for being connected with an output end of the current detection device, an output end of the latch circuit is used for being connected with an input end of the driving circuit, the current detection device provides a current state signal (for example, a PWM signal with different duty cycles), after the signal processing circuit receives the current state signal, the signal processing circuit processes to generate an analog signal (digital-analog conversion), the voltage comparison circuit compares a corresponding voltage value of the analog signal with a preset voltage value, for example, when the corresponding voltage value of the analog signal is less than the preset voltage value (a comparator threshold value, which can be configured according to actual conditions), the voltage comparison circuit outputs a high level, at this time, the driving circuit at the back end cannot be enabled, and when the corresponding voltage value of the analog signal is greater than the preset voltage value, the voltage comparison circuit outputs a low level, at this time, the driving circuit at the back end can be enabled, so that the driving circuit can disconnect the relay of the power supply loop, to realize fast overcurrent shutdown and timely protection of the load. Specifically, the signal processing circuit and the voltage comparison circuit can convert different types of current state signals into a high level or a low level, to realize processing of different types of current state signals, and the latch circuit is used for latching the processed signal, to control the driving circuit to control the load accordingly.

[0028] In this embodiment, after the signal processing circuit processes the current state signal with different duty cycles provided by the current detection device, the signal processing circuit generates an analog signal, the voltage comparison circuit compares a corresponding voltage value of the analog signal with a preset voltage value, and converts the corresponding voltage value into a level driving signal, so that the driving circuit can control the relay and other devices of the power supply loop according to the level driving signal, for example, the driving circuit can disconnect the relay of the power supply loop, to realize fast overcurrent shutdown and timely protection of the load. Therefore, this embodiment can be compatible with current state signals with different duty cycles, and compared with the technical solution in the related art which can only process the current in a high level or a low level, this embodiment can process different types of overcurrent signals.

[0029] Optionally, the signal processing circuit includes a first resistor R1 and a first capacitor C1, one end of the first resistor R1 and one end of the first capacitor C1 are output ends of the signal processing circuit, and are connected with an inverting input end IN- of the voltage comparison circuit, the other end of the first resistor R1 is used for being connected with the current detection device, and the other end of the first capacitor C1 is grounded.

[0030] Specifically, in combination with Figure 2As shown, the signal processing circuit includes a first resistor R1 and a first capacitor C1, one end of the first resistor R1 and one end of the first capacitor C1 are the output end of the signal processing circuit, and are connected with the reverse input end IN- of the voltage comparison circuit, the other end of the first capacitor C1 is grounded; the other end of the first resistor R1 is connected with the current detection device, receives the PWM signal (OC_IN) from the current detection device, and the filter network composed of the first resistor R1 and the first capacitor C1 can shape or denoise the PWM signal, and output a smooth analog signal.

[0031] In this optional embodiment, the filter network composed of the first resistor R1 and the first capacitor C1 can shape or denoise the PWM signal, thereby outputting a smooth analog signal.

[0032] Optionally, the voltage comparison circuit includes a voltage comparator U1 and a filter circuit, the reverse input end IN- of the voltage comparator U1 is connected with the output end of the signal processing circuit, the output end OUT of the voltage comparator U1 is connected with the input end of the filter circuit, and the output end of the filter circuit is connected with the input end of the latch circuit.

[0033] Specifically, in combination with Figure 2 As shown, the voltage comparison circuit includes a voltage comparator U1 and a filter circuit, the reverse input end IN- of the voltage comparator U1 is connected with the output end of the signal processing circuit, the output end OUT of the voltage comparator U1 is connected with the input end of the filter circuit, and the output end of the filter circuit is connected with the input end of the latch circuit, the level driving signal (high level or low level) calculated by the voltage comparator U1 is output through the output end OUT, processed by the filter circuit, and then sent to the latch circuit.

[0034] The voltage comparison circuit further includes a fifth capacitor C5, the supply end VCC of the voltage comparator U1 is connected to 5V, and the fifth capacitor C5 is a power port voltage stabilizing capacitor of the voltage comparator U1.

[0035] In this optional embodiment, by setting the voltage comparison circuit to include the voltage comparator U1 and the filter circuit, the voltage comparator U1 calculates the level driving signal according to the PWM signal, and then the filter circuit processes and sends it to the latch circuit, which can ensure the stability of the signal level state and the like.

[0036] Optionally, the filter circuit comprises a third capacitor C3, a fourth resistor R4 and a fifth resistor R5, two ends of the fifth resistor R5 are connected with the output terminal OUT of the voltage comparator U1 and the input terminal of the latch circuit respectively, one end of the third capacitor C3 is connected on the connecting line between the fifth resistor R5 and the output terminal OUT of the voltage comparator U1, one end of the fourth resistor R4 is connected on the connecting line between the fifth resistor R5 and the latch circuit, and the other end of the third capacitor C3 is grounded together with the other end of the fourth resistor R4.

[0037] Specifically, in combination with Figure 2 As shown in the figure, the filter circuit comprises a third capacitor C3, a fourth resistor R4 and a fifth resistor R5, two ends of the fifth resistor R5 are connected with the output terminal OUT of the voltage comparator U1 and the input terminal of the latch circuit respectively, and the fifth resistor R5 can reduce the impact current between the output terminal OUT of the voltage comparator U1 and the data input terminal D of the latch U2; one end of the third capacitor C3 is connected on the connecting line between the fifth resistor R5 and the output terminal OUT of the voltage comparator U1, one end of the fourth resistor R4 is connected on the connecting line between the fifth resistor R5 and the latch circuit, and the other end of the third capacitor C3 is grounded together with the other end of the fourth resistor R4; the third capacitor C3 and the fourth resistor R4 can connect the output terminal OUT to the ground, the third capacitor C3 can ensure the stability of the output terminal OUT voltage of the comparator U1, and the fourth resistor R4 can provide a stable pull-down low level for the output terminal OUT of the voltage comparator U1 and the data input terminal D of the latch U2, so as to prevent the occurrence of an uncertain signal level state.

[0038] In the optional embodiment, the filter circuit comprises the third capacitor C3, the fourth resistor R4 and the fifth resistor R5, which is beneficial to improve the stability of the voltage comparison circuit.

[0039] Optionally, the voltage comparison circuit further comprises a fifteenth resistor R15, two ends of the fifteenth resistor R15 are connected with the output terminal OUT of the voltage comparator and the positive input terminal IN+ of the voltage comparator respectively.

[0040] Specifically, in combination with Figure 2 As shown in the figure, the voltage comparison circuit further comprises a fifteenth resistor R15, and the output terminal OUT of the voltage comparator is connected with the positive input terminal IN+ through the fifteenth resistor R15, so as to form a hysteresis comparator; the hysteresis comparator can enhance the noise suppression capability of the voltage comparison circuit, and prevent misoperation caused by interference.

[0041] In the optional embodiment, the fifteenth resistor R15 forms a hysteresis comparator, and the hysteresis comparator can enhance the noise suppression capability of the voltage comparison circuit, and prevent misoperation caused by interference.

[0042] Optionally, the overcurrent signal processing latch circuit further comprises a sampling circuit, the sampling circuit comprising a ninth resistor R9 and a sixth capacitor C6, one end of the ninth resistor R9 being connected with the output terminal OUT of the voltage comparator U1, the other end of the ninth resistor R9 being connected with one end of the sixth capacitor C6, the connection point between the ninth resistor R9 and the sixth capacitor C6 being connected with the input terminal of the controller, the other end of the sixth capacitor C6 being grounded.

[0043] Specifically, in combination with Figure 2 As shown in the figure, the overcurrent signal processing latch circuit further comprises a sampling circuit, the sampling circuit comprising a ninth resistor R9 and a sixth capacitor C6, one end of the ninth resistor R9 being connected with the output terminal OUT of the voltage comparator U1, the other end of the ninth resistor R9 being connected with one end of the sixth capacitor C6, the connection point between the ninth resistor R9 and the sixth capacitor C6 being connected with the input terminal OUT_MCU of the controller, the other end of the sixth capacitor C6 being grounded, and the filter network composed of the ninth resistor R9 and the sixth capacitor C6 can make the current state collected by the controller MCU more accurate.

[0044] In the optional embodiment, by setting the sampling circuit to comprise the ninth resistor R9 and the sixth capacitor C6, the filter network composed of the ninth resistor R9 and the sixth capacitor C6 can make the current state collected by the controller MCU more accurate.

[0045] Optionally, the overcurrent signal processing latch circuit further comprises a voltage dividing circuit, the voltage dividing circuit comprising a second capacitor C2, a second resistor R2 and a third resistor R3, one end of the second capacitor C2, one end of the second resistor R2 and one end of the third resistor R3 being connected with the positive input terminal IN+ of the voltage comparator U1, the other end of the second resistor R2 being connected with the power supply, and the other end of the second capacitor C2 and the other end of the third resistor R3 being grounded.

[0046] Specifically, in combination with Figure 2 As shown in the figure, the overcurrent signal processing latch circuit further comprises a voltage dividing circuit, the voltage dividing circuit comprising a second capacitor C2, a second resistor R2 and a third resistor R3, one end of the second capacitor C2, one end of the second resistor R2 and one end of the third resistor R3 being connected with the positive input terminal IN+ of the voltage comparator U1, the other end of the second resistor R2 being connected with the power supply (5V), and the other end of the second capacitor C2 and the other end of the third resistor R3 being grounded, the second resistor R2 and the third resistor R3 forming a voltage dividing network to provide a voltage reference value (i.e. a preset voltage value) to the positive input terminal IN+ of the voltage comparator U1, and the second capacitor C2 can ensure the voltage stability of the positive input terminal IN+ of the voltage comparator U1 to prevent voltage fluctuation.

[0047] In this optional embodiment, by setting the voltage dividing circuit including the second capacitor C2, the second resistor R2 and the third resistor R3, the voltage at the positive input end IN+ of the voltage comparator U1 can be stabilized while providing the voltage reference value, and voltage fluctuation can be prevented.

[0048] Optionally, the latch circuit includes a latch U2, a data input end D of the latch U2 is connected with the output end of the voltage comparison circuit, a clock input end CLK of the latch U2 is used for being connected with the output end of the current detection device, and an inverse output end Q~ of the latch U2 is used for being connected with the input end of the driving circuit.

[0049] Specifically, in combination with Figure 2 As shown in the figure, the latch circuit includes a latch U2 (the control logic is as shown in the figure Figure 3 As shown in the figure, the latch U2, a data input end D (L represents low level, H represents high level, and X represents any level) of the latch U2 is connected with the output end of the voltage comparison circuit, a clock input end CLK (↑ represents rising edge, and L represents low level) of the latch U2 is connected with the output end of the current detection device through the sixteenth resistor (R16) as an edge signal input, and an inverse output end Q~ (L represents low level, H represents high level, and Q0 represents initial output state) of the latch U2 is connected with the input end of the driving circuit, and the inverse output end Q~ is pulled down to the ground through the eighth resistor (R8) to ensure that the pin level is stable.

[0050] In the figure, a ground end GND of the latch U2 is grounded, a power supply end VCC of the latch U2 is connected to a 5V power supply, and the fourth capacitor C4 is used for stabilizing the 5V power supply port.

[0051] In this embodiment, the latch U2 is a single-channel latch, includes one-way data input, one-way clock signal input and one-way latch state output, can realize state acquisition and processing of a single signal, simplifies circuit design, saves cost and space. In related technologies, for example, the latch circuit for overcurrent fault signal based on a flip-flop, the latch is usually a multi-channel latch, and the circuit is relatively complex and high in cost. In this embodiment, an overcurrent trigger and a latch function are realized by using a single comparator and a single-channel latch, so that the circuit complexity and cost are effectively reduced.

[0052] In this optional embodiment, by setting the latch circuit including the latch U2, the level driving signal is latched through the latch U2, and then the switching state of the relay can be controlled through the driving circuit, the power supply loop can be turned on or turned off, the fast overcurrent shutdown can be realized, and the load can be protected in time.

[0053] Optionally, the overcurrent signal processing latch circuit further comprises a pull-down circuit, the pull-down circuit comprising a pull-down transistor Q1, a thirteenth resistor R13 and a fourteenth resistor R14, the drain of the pull-down transistor Q1 being connected with the input end D of the latch U2, the gate of the pull-down transistor Q1 being grounded through the thirteenth resistor R13, the gate of the pull-down transistor Q1 being further connected with the output end of the controller MCU through the fourteenth resistor R14, and the source of the pull-down transistor Q1 being grounded.

[0054] Specifically, in combination with Figure 2 As shown in the figure, the overcurrent signal processing latch circuit further comprises a pull-down circuit, the pull-down circuit comprising a pull-down transistor Q1, a thirteenth resistor R13 and a fourteenth resistor R14, the drain of the pull-down transistor Q1 being connected with the input end D of the latch U2, the gate of the pull-down transistor Q1 being grounded through the thirteenth resistor R13, the gate of the pull-down transistor Q1 being connected with the output end (PD_MCU) of the controller MCU through the fourteenth resistor R14, and the source of the pull-down transistor Q1 being grounded, so that the overcurrent state can be maintained and restored through the pull-down circuit and directly controlled by the output pin of the controller.

[0055] In the optional embodiment, the overcurrent signal processing latch circuit further comprises a pull-down circuit, and the overcurrent state is maintained and restored through the pull-down circuit.

[0056] As Figure 4 shown, the overcurrent protection device provided by the embodiment of the utility model, including current detection device, drive circuit, relay and overcurrent signal processing latch circuit, current detection device's input end is used with load connection, current detection device's output end with overcurrent signal processing latch circuit's input end is connected, overcurrent signal processing latch circuit's output end with drive circuit's input end is connected, drive circuit's output end with relay is connected, and the relay is used for controlling the on-off of the power supply circuit of the load.

[0057] The current detection device is used for outputting a corresponding current state signal according to the current state of the load, and the overcurrent signal processing latch circuit is used for outputting a corresponding level according to the current state signal to drive the drive circuit to control the switching state of the relay.

[0058] Specifically, the overcurrent protection device comprises a current detection device, a driving circuit, a relay and an overcurrent signal processing latch circuit, an input end of the current detection device is connected with a load, an output end of the current detection device is connected with an input end of the overcurrent signal processing latch circuit, an output end of the overcurrent signal processing latch circuit is connected with an input end of the driving circuit, and an output end of the driving circuit is connected with the relay, wherein the current detection device is composed of a current collection circuit and a current collection chip, the overcurrent signal processing latch circuit is composed of a signal processing and sampling circuit and a latch signal processing circuit, the signal processing and sampling circuit comprises the signal processing circuit, the voltage dividing circuit, the voltage comparison circuit and the sampling circuit mentioned above, the latch signal processing circuit comprises the pull-down circuit and the latch circuit mentioned above, the current detection device outputs a corresponding current state signal according to a current state of the load, the overcurrent signal processing latch circuit outputs a corresponding level according to the current state signal output by the current detection device, so that the driving circuit can control a switching state of the relay, the relay controls on-off of a power supply loop of the load, the power supply loop is turned on or turned off, rapid overcurrent shutdown is realized, and the load is protected in time.

[0059] The principle of the overcurrent protection device is as follows:

[0060] (1) When the overcurrent detection function of the current detection device is not started (software is not configured) after the current detection device is powered on, the current state OC_IN signal is low, that is, the reverse input end IN- of the voltage comparator U1 is low. The positive input end IN+ of the voltage comparator U1 has a voltage dividing voltage from the voltage dividing resistors R2 and R3, which is higher than the reverse input end IN- of the comparator U1, so the output end OUT of the voltage comparator U1 is high. The data pin D of the latch U2 is also high, and the clock CLK pin is low, so the reverse output pin Q- of the latch is low, and the rear-end driving circuit is not enabled.

[0061] (2) After the overcurrent detection function of the current detection device is started, and when the current does not reach the preset overcurrent threshold, the input frequency of the current state OC_IN signal is 16 kHz, the high level duty cycle is 25%, and the high level amplitude is 5V. At this time, the PWM signal forms a stable voltage at the IN- pin of the comparator U1 after passing through the signal processing circuit. The voltage value is still lower than the voltage at the IN+ end of the comparator, so the output end OUT of the voltage comparator U1 still outputs high. At this time, the clock pin CLK of the latch U2 has 25% PWM signal input, but since the data pin D is always high, the reverse output pin Q- is also low when the CLK pin is rising and the D pin is high, and the rear-end driving circuit is not enabled.

[0062] (3) After the current detection device starts the overcurrent detection function, when the current reaches the preset overcurrent threshold, the input frequency of the current state OC_IN signal remains unchanged, and the high level duty cycle becomes 75%. After the signal processing circuit, a higher voltage than the IN+ pin is formed at the IN- pin of the comparator U1. At this time, the output state of the voltage comparator U1 changes, and the output pin OUT changes from high level to low level, that is, the data input pin D of the latch U2 is low. After the rising edge of the current state signal OC_IN is collected, the output Q~ pin of the latch outputs a high level, which is used to enable the rear-end drive circuit and disconnect the load for protection. In this process, the resistor R1 and the capacitor C1 are used to convert the digital PWM signal at this frequency into an analog voltage. By reasonably configuring the parameters of the resistor R1 and the capacitor C1, the voltage at the IN- end is stably and monotonously increased. The output pin OUT of the comparator U1 is prevented from repeatedly jumping between high and low levels, which affects the stability of the output. The OUT pin of the voltage comparator U1 is also connected to its own positive input end IN+ through a feedback resistor R15 to form a hysteresis comparator, thereby enhancing the noise suppression capability of the voltage comparison circuit and preventing interference from causing misoperation. The controller simultaneously samples the voltage at the OUT pin of the voltage comparator U1, and when it is confirmed that the level of the OUT pin is pulled low due to overcurrent, the controller enables the PD_MCU pin to turn on the MOS tube Q1 and strongly pull down the D pin of the latch U2 to low.

[0063] (4) Overcurrent recovery: when the current detection device detects that the current is not in an overcurrent state, the OC_IN signal will change from a 75% duty cycle signal to a 25% duty cycle signal. At this time, the IN- voltage of the voltage comparator U1 will start to decrease, and when the voltage at this point is lower than the voltage at the IN+ pin, the output end OUT of the U1 will change from low level to high level. Before this, the controller has pulled down the D pin of the latch U2 through the pull-down circuit to prevent the output end Q~ of the latch U2 from changing from high level to low level, which causes the rear-end load to recover to the connected state. This processing process judges whether the overcurrent fault is cleared through the controller, which can reduce the risk of unintended conduction of the load. If the controller judges that the overcurrent fault has been handled, the PD_MCU signal is set to low, and the D pin of the latch U2 is not forcibly pulled down to low level through Q1. Then the latch U2 returns to the normal state of detecting the output OUT pin of the voltage comparator U1.

[0064] Although the utility model discloses as above, the protection scope of the utility model is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model, and these changes and modifications will all fall within the protection scope of the utility model.

Claims

1. An overcurrent signal processing latch circuit, comprising: The signal processing circuit, the voltage comparison circuit and the latch circuit are connected in series, the output of the signal processing circuit is connected with the input of the voltage comparison circuit, the output of the voltage comparison circuit is connected with the input of the latch circuit, the input of the signal processing circuit and the input of the latch circuit are connected with the output of the current detection device, and the output of the latch circuit is connected with the input of the driving circuit. The signal processing circuit is used for receiving the current state signal from the current detection device and processing the current state signal to generate an analog signal, the voltage comparison circuit is used for comparing the corresponding voltage value of the analog signal with a preset voltage value to output a corresponding level, and the latch circuit is used for driving the driving circuit according to the level.

2. The overflow signal processing latch circuit of claim 1, wherein, The signal processing circuit comprises a first resistor and a first capacitor, one end of the first resistor and one end of the first capacitor are the output of the signal processing circuit, and both are connected with the reverse input of the voltage comparison circuit, the other end of the first resistor is connected with the current detection device, and the other end of the first capacitor is grounded.

3. The overflow signal processing latch circuit of claim 1, wherein, The voltage comparison circuit comprises a voltage comparator and a filter circuit, the reverse input of the voltage comparator is connected with the output of the signal processing circuit, the output of the voltage comparator is connected with the input of the filter circuit, and the output of the filter circuit is connected with the input of the latch circuit.

4. The overflow signal processing latch circuit of claim 3, wherein, The filter circuit comprises a third capacitor, a fourth resistor and a fifth resistor, the two ends of the fifth resistor are connected with the output of the voltage comparator and the input of the latch circuit respectively, one end of the third capacitor is connected on the connection line between the fifth resistor and the output of the voltage comparator, one end of the fourth resistor is connected on the connection line between the fifth resistor and the latch circuit, and the other end of the third capacitor and the other end of the fourth resistor are grounded.

5. The overflow signal processing latch circuit of claim 3, wherein, The voltage comparison circuit further comprises a fifteenth resistor, the two ends of the fifteenth resistor are connected with the output of the voltage comparator and the positive input of the voltage comparator respectively.

6. The overflow signal processing latch circuit of claim 3, wherein, The sampling circuit comprises a ninth resistor and a sixth capacitor, one end of the ninth resistor is connected with the output of the voltage comparator, the other end of the ninth resistor is connected with one end of the sixth capacitor, the connection point between the ninth resistor and the sixth capacitor is connected with the input of the controller, and the other end of the sixth capacitor is grounded.

7. The overflow signal processing latch circuit of claim 3, wherein, The voltage comparison circuit further comprises a fifteenth resistor, the two ends of the fifteenth resistor are connected with the output of the voltage comparator and the positive input of the voltage comparator respectively.

8. The overflow signal processing latch circuit of claim 1, wherein, The latch circuit comprises a latch, a data input end of the latch is connected with an output end of the voltage comparison circuit, a clock input end of the latch is used for being connected with an output end of the current detection device, and an inverse output end of the latch is used for being connected with an input end of the driving circuit.

9. The overflow signal processing latch circuit of claim 8, wherein, The latch circuit further comprises a pull-down circuit, the pull-down circuit comprises a pull-down transistor, a thirteenth resistor and a fourteenth resistor, a drain of the pull-down transistor is connected with the input end of the latch, a gate of the pull-down transistor is grounded through the thirteenth resistor, the gate of the pull-down transistor is further connected with an output end of a controller through the fourteenth resistor, and a source of the pull-down transistor is grounded.

10. An overcurrent protection device, characterized by The latch circuit comprises a current detection device, a driving circuit, a relay and the overcurrent signal processing latch circuit according to any one of claims 1 to 9, an input end of the current detection device is used for being connected with a load, an output end of the current detection device is connected with an input end of the overcurrent signal processing latch circuit, an output end of the overcurrent signal processing latch circuit is connected with an input end of the driving circuit, an output end of the driving circuit is connected with the relay, and the relay is used for controlling on-off of a power supply circuit of the load. The current detection device is used for outputting a corresponding current state signal according to a current state of the load, and the overcurrent signal processing latch circuit is used for outputting a corresponding level according to the current state signal, so as to drive the driving circuit to control a switching state of the relay.

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