Output circuit for preventing short circuit

Abstract

The utility model relates to electronic circuit protection technical field discloses an output circuit with higher safety and short -circuit protection function, including the controller (110) for output control signal, push -pull output circuit (120), low voltage detection circuit (130) and reset and protection circuit (140), wherein, push -pull output circuit (120) is used to receive the control signal of controller (110) input, to trigger push -pull output circuit (120)'s on / off state, low voltage detection circuit (130) is used to obtain the high level voltage signal of push -pull output circuit (120) output, reset and protection circuit (140) are used to obtain level signal, and according to the state output or off of level signal to the power of push -pull output circuit (120).

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit protection technology, and more specifically, to an output circuit for short circuit protection. Background Technology

[0002] Push-pull output circuits are commonly used power output structures in electronic devices. With their ability to effectively suppress harmonic distortion and improve output efficiency, they are widely used in electronic systems such as LED drivers and simple control modules, covering power output scenarios from milliwatts to watts.

[0003] In the current technology field, the short-circuit protection design of push-pull output circuits exhibits a significant polarization problem, making it difficult to adapt to cost-sensitive, low-to-medium power applications with low functional requirements. The specific technical status and shortcomings are as follows:

[0004] On the one hand, for low-power applications with power levels of milliwatts and below, existing technologies usually omit short-circuit protection design. In actual applications, even with milliwatt-level output, the circuit current may suddenly increase due to unexpected short circuits in the load (such as incorrect wiring or contact with external foreign objects), which may burn out core components such as power transistors and driver chips in the push-pull circuit.

[0005] On the other hand, for medium and high power applications above the milliwatt level, although existing technologies will set up short-circuit protection mechanisms, the protection schemes generally rely on dedicated current detection equipment such as series resistors, Hall elements, and current sensors to monitor short-circuit current.

[0006] For example, by connecting a high-precision sampling resistor in series in the output circuit, the current is detected by the change in voltage across the resistor, and then the subsequent circuitry such as a comparator and microcontroller determines whether protection is triggered. Although this type of solution can achieve short-circuit protection, it has obvious drawbacks:

[0007] Firstly, the procurement cost of current detection equipment (especially Hall elements and high-precision sampling resistors) is high, which leads to a significant increase in the cost of the entire protection circuit. The cost is too high and the functions are redundant, resulting in the problem of "using too much material for too little use".

[0008] Secondly, the series current sensing resistor in the output circuit will inevitably produce a load effect. The voltage drop across the resistor will directly lead to a reduction in the output voltage amplitude, affecting the output accuracy of the push-pull circuit. Utility Model Content

[0009] The technical problem to be solved by this utility model is that the short-circuit protection design of the above-mentioned push-pull output circuit in the prior art presents obvious polarization, which makes it difficult to adapt to the defects of low- and medium-power application scenarios with low cost sensitivity and low functional requirements. This utility model provides an output circuit with high safety and short-circuit protection function.

[0010] The technical solution adopted by this utility model to solve its technical problem is: to construct a short-circuit-proof output circuit, which includes:

[0011] Controller;

[0012] A push-pull output circuit, one of its input terminals is connected to one of the output terminals of the controller, for receiving a control signal input by the controller, the control signal being used to trigger the on / off state of the push-pull output circuit;

[0013] A low-voltage detection circuit, one end of which is connected to the power supply input terminal of the push-pull output circuit, is used to acquire the high-level voltage signal output by the push-pull output circuit.

[0014] A reset and protection circuit, one end of which is coupled to the other end of the low-voltage detection circuit, is used to acquire the level signal and output or shut off the power supply to the push-pull output circuit according to the state of the level signal.

[0015] In some implementations, when the input control signal is low, the push-pull output circuit outputs a high level to the load.

[0016] When the input control signal is high, the push-pull output circuit outputs a low level to the load.

[0017] In some implementations, the low-voltage detection circuit compares the high-level voltage signal output by the push-pull output circuit with a set value.

[0018] If the level signal output by the push-pull output circuit is high and the voltage amplitude is lower than the set value, then a low level is output to the reset and protection circuit.

[0019] If the high-level voltage amplitude of the signal is higher than the set value, a high level is output to the reset and protection circuit.

[0020] When the low-voltage detection circuit detects that the high-level voltage amplitude is too low, the reset and protection circuit activates protection measures based on the current voltage amplitude, cutting off the connection between the power supply and the push-pull output circuit.

[0021] In some implementations, the reset and protection circuit will latch itself after triggering the short-circuit protection, maintaining the disconnection between the power supply and the push-pull output circuit, and feeding back a high-level signal to the controller.

[0022] The controller determines the output state of the push-pull output circuit based on the input high level.

[0023] In some embodiments, the push-pull output circuit includes a first MOSFET and a second MOSFET.

[0024] The gates of the first MOSFET and the second MOSFET are connected to an output terminal of the controller.

[0025] The gates of the first MOSFET and the second MOSFET are also connected to one end of the low-voltage detection circuit through a first resistor.

[0026] The source of the first MOSFET is connected to the common terminal.

[0027] The drain of the first MOSFET is connected to the drain of the second MOSFET.

[0028] The source of the second MOS transistor is connected to one end of the low-voltage detection circuit.

[0029] In some embodiments, the low-voltage detection circuit includes a voltage divider module and a switching module.

[0030] The first terminal of the voltage divider module is connected to the source of the second MOS transistor.

[0031] The second terminal of the voltage divider module is coupled to the first terminal of the switch module.

[0032] The second terminal of the switch module is connected to one terminal of the reset and protection circuit.

[0033] The third terminal of the switch module is connected to the other terminal of the reset and protection circuit.

[0034] The third terminal of the voltage divider module is connected to the common terminal.

[0035] In some embodiments, the voltage divider module includes a second resistor and a third resistor connected in series.

[0036] The switching module includes a first transistor and a fourth resistor.

[0037] One end of the second resistor is coupled to the source of the second MOSFET.

[0038] The base of the first transistor is connected to the connection terminal of the second resistor and the third resistor.

[0039] The collector of the first transistor is connected to one end of the reset and protection circuit.

[0040] The emitter of the first transistor is connected to the other end of the reset and protection circuit.

[0041] One end of the fourth resistor is connected to the collector of the first transistor.

[0042] The other ends of the third resistor and the fourth resistor are connected to the common terminal.

[0043] In some embodiments, the reset and protection circuit includes at least a third MOSFET and a fourth MOSFET.

[0044] The gate of the third MOS transistor and the drain of the fourth MOS transistor are connected to the power supply through a fifth resistor.

[0045] The source of the third MOS transistor is connected to the power supply.

[0046] The gate of the fourth MOS transistor is connected to the collector of the first transistor.

[0047] The source of the fourth MOS transistor is connected to the common terminal.

[0048] In some embodiments, the reset and protection circuit further includes a fifth MOSFET.

[0049] The gate of the fifth MOS transistor is connected to the reset terminal of the controller.

[0050] The drain of the fifth MOS transistor is connected to the gate of the third MOS transistor and the drain of the fourth MOS transistor, respectively.

[0051] The drain of the fifth MOSFET is connected to the feedback terminal of the controller.

[0052] The source of the fifth MOS transistor is connected to the common terminal.

[0053] In some embodiments, the reset and protection circuit further includes a first capacitor, one end of which is connected to one end of the fifth resistor.

[0054] The other end of the first capacitor is connected to the common terminal.

[0055] The short-circuit protection output circuit of this invention includes a controller for outputting control signals, a push-pull output circuit, a low-voltage detection circuit, and a reset and protection circuit. The push-pull output circuit receives a control signal input from the controller to trigger its on / off state. The low-voltage detection circuit acquires a high-level voltage signal output by the push-pull output circuit. The reset and protection circuit acquires the voltage level signal and outputs or shuts off the power supply to the push-pull output circuit based on the state of the voltage level signal. Compared with existing technologies, the real-time detection of the push-pull output circuit via the low-voltage detection circuit ensures accurate voltage supply to the load, avoiding output signal distortion or power supply instability caused by load effects.

[0056] On the other hand, when no short circuit occurs in the circuit, the reset and protection circuit outputs a low level, feeding back a "circuit normal" signal to the controller. When a short circuit triggers the protection mechanism at the output of the push-pull output circuit, the reset and protection circuit outputs a high level, feeding back a "short circuit fault" signal in real time and cutting off the output power.

[0057] In addition, the voltage detection threshold of the low-voltage detection circuit is adjustable, which can adapt to the needs of different load scenarios. Attached Figure Description

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0059] Figure 1 This is a circuit diagram of an embodiment of the short-circuit protection output circuit provided by this utility model. Detailed Implementation

[0060] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0061] like Figure 1 As shown, in the first embodiment of the short-circuit protection output circuit of this utility model, the short-circuit protection output circuit 10 includes a controller 110, a push-pull output circuit 120, a low-voltage detection circuit 130, and a reset and protection circuit 140.

[0062] The controller 110 has the functions of logic operation, level detection / judgment, control signal output, and reset signal output.

[0063] The push-pull output circuit 120 has the function of logic level output. The level of its output terminal (corresponding to Vo) is out of phase with that of its input terminal (corresponding to Vi). The load (corresponding to RL) is connected to the output terminal (corresponding to Vo), while the input terminal (corresponding to Vi) is connected to the controller 110. The logic level of the input terminal (corresponding to Vi) is provided by the control terminal or drive terminal of the controller 110.

[0064] When the control signal input to the input terminal (corresponding to Vi) is low, the output terminal (corresponding to Vo) will output a high level to the load (corresponding to RL);

[0065] When the control signal input to the input terminal (corresponding to Vi) is high, the output terminal (corresponding to Vo) will output a low level to the load (corresponding to RL);

[0066] The function of the low voltage detection circuit 130 is to detect whether the high-level voltage amplitude of the output terminal (corresponding to Vo) is lower than the set value (or voltage threshold) when the output terminal (corresponding to Vo) outputs a high level, and to feed back the detection result to the reset and protection circuit 140.

[0067] If the high-level voltage amplitude output at the output terminal (corresponding to Vo) is lower than the set value (or voltage threshold), a low level is output to the reset and protection circuit 140.

[0068] If the high-level voltage amplitude output at the output terminal (corresponding to Vo) is higher than the set value (or voltage threshold), then a high level is output to the reset and protection circuit 140.

[0069] The function of the reset and protection circuit 140 is to activate protection measures when the low voltage detection circuit 130 detects that the high voltage amplitude is too low, and disconnect the power supply VCC from the push-pull output circuit 120 to prevent the power supply VCC from short-circuiting.

[0070] After the short circuit protection is triggered, the reset and protection circuit 140 will self-lock and keep disconnected from the power supply VCC and the push-pull output circuit 120, and then feed back a high level as the output. The back-end controller 110 or driver can detect whether this high level output has occurred to determine whether a short circuit has occurred at the push-pull output terminal (corresponding to Vo).

[0071] Meanwhile, after the short-circuit self-locking protection is triggered, and the short-circuit fault is cleared, the self-locking protection needs to be reset and unlocked by a high-level pulse at the RST port. Only after unlocking can the push-pull output circuit 120 output normally.

[0072] Specifically, the controller 110 is configured in the output circuit to output at least one control signal and a reset signal;

[0073] Among them, one input terminal (corresponding to Vi) of the push-pull output circuit 120 is connected to one output terminal (corresponding to Vi) of the controller 110, and is used to receive a control signal input by the controller 110. The control signal (high level / low level) is used to trigger the on / off state of the push-pull output circuit 120.

[0074] Furthermore, one end of the low-voltage detection circuit 130 is connected to the power supply input terminal of the push-pull output circuit 120 to obtain the high-level voltage signal output by the push-pull output circuit 120.

[0075] One end of the reset and protection circuit 140 is coupled to the other end of the low voltage detection circuit 130 to obtain the level signal fed back by the low voltage detection circuit 130. It can determine whether a short circuit has occurred at the output terminal (corresponding to Vo) or the load (corresponding to RL) of the push-pull output circuit 120 according to the state of the level signal (high level / low level), and control the output or shut off the power supply to the push-pull output circuit 120 accordingly.

[0076] Using this technical solution, on the one hand, the push-pull output circuit 110 is detected in real time by the low-voltage detection circuit 120, which can ensure that the load end receives accurate voltage supply and avoid output signal distortion or power supply instability caused by load effect.

[0077] On the other hand, when no short circuit occurs in the circuit, the reset and protection circuit 140 outputs a low level, feeding back a "circuit normal" signal to the controller. When the output terminal of the push-pull output circuit 120 is short-circuited and triggers the protection mechanism, the reset and protection circuit 140 outputs a high level, feeding back a "short circuit fault" signal in real time and cutting off the output power.

[0078] In addition, the voltage detection threshold of the low-voltage detection circuit 130 is adjustable to adapt to different load scenarios.

[0079] In some implementations, to ensure the reliability of the power signal output by the push-pull output circuit 120, when the control signal input to the controller 110 is low, the push-pull output circuit 120 outputs a high level to the load (corresponding to RL).

[0080] When the control signal input to the controller 110 is high, the push-pull output circuit 120 outputs a low level to the load (corresponding to RL).

[0081] In some implementations, to ensure the reliability of the load (corresponding to RL) operation, a set value (or voltage threshold) can be set within the low-voltage detection circuit 130.

[0082] The low-voltage detection circuit 130 compares the high-level voltage signal output by the push-pull output circuit 120 with a set value (or voltage threshold).

[0083] If the output signal of the push-pull output circuit 120 is high and the voltage amplitude is lower than the set value (or voltage threshold), then a low level is output to the reset and protection circuit 140.

[0084] If the high-level voltage amplitude of the signal exceeds the set value (or voltage threshold), a high level is output to the reset and protection circuit 140.

[0085] When the low-voltage detection circuit 130 detects that the high-level voltage amplitude is too low, the reset and protection circuit 140 activates protection measures according to the current voltage amplitude, cutting off the connection between the power supply VCC and the push-pull output circuit 120.

[0086] In some implementations, to ensure the reliability of the load (corresponding to RL), the reset and protection circuit 140 latches itself after triggering the short-circuit protection, maintains the connection between the disconnected power supply VCC and the push-pull output circuit 120, and feeds back a high level to the controller 110.

[0087] The controller 110 can determine the output state (i.e., short circuit state) of the push-pull output circuit 120 based on the high level input.

[0088] In some embodiments, the push-pull output circuit 120 includes a first MOSFET Q101 and a second MOSFET Q102, wherein the first MOSFET Q101 is selected as an N-channel MOSFET and the second MOSFET Q102 is selected as a P-channel MOSFET, both of which have the function of switching;

[0089] Specifically, the gates of the first MOSFET Q101 and the second MOSFET Q102 are connected to an output terminal (corresponding to Vi) of the controller 110, and are used to receive control signals input by the controller 110;

[0090] The gates of the first MOSFET Q101 and the second MOSFET Q102 are also connected to one end of the low-voltage detection circuit 130 through the first resistor R101, wherein the first resistor R101 is a pull-up resistor.

[0091] The source of the first MOSFET Q101 is connected to the common terminal (corresponding to GND).

[0092] The drain of the first MOSFET Q101 is connected to the drain of the second MOSFET Q102.

[0093] The source of the second MOSFET Q102 is connected to one end of the low-voltage detection circuit 130.

[0094] Its working principle is as follows: The first resistor R101 provides a default pull-up high level for the gates of the first MOSFET Q101 and the second MOSFET Q102, so that when the input Vi is floating, the first MOSFET Q101 is turned on and the second MOSFET Q102 is turned off, and Vo is output low level by default; Assuming that the load (corresponding to RL) is not short-circuited, the third MOSFET Q103 of the reset and protection circuit 140 is normally turned on, and the voltage at point C becomes VCC;

[0095] When Vi inputs a high level, point A is at a high level, then the second MOSFET Q102 is turned off, the first MOSFET Q101 is turned on, point B is shorted to GND, and Vo outputs a low level.

[0096] When Vi is low, point A is low, so the first MOSFET Q101 is turned off and the second MOSFET Q102 is turned on. Point B is shorted to point C. Since the voltage at point C is VCC, Vo outputs a high level.

[0097] In other words, in the absence of a short circuit, the output of Vo is out of phase with the input Vi, and the desired output level of Vo can be obtained by giving the input Vi.

[0098] If a short circuit occurs at the load end, the reset and protection circuit 140 will disconnect the power supply VCC from the push-pull output circuit 120 to prevent a power short circuit. At this time, the voltage at point C will be floating. Regardless of whether the input Vi is high or low, the output Vo will be low.

[0099] The first MOSFET Q101 will only turn on when the Vi input is high and turn off when the Vi input is low.

[0100] The second MOSFET Q102 will not conduct regardless of whether the input Vi is high or low.

[0101] In some implementations, to allow for flexibility in adjusting the voltage detection threshold, the low-voltage detection circuit 130 may include a voltage divider module 131 and a switching module 132.

[0102] The first terminal of the voltage divider module 131 is connected to the source of the second MOSFET Q102, and is used to detect the high-level voltage signal at the load (corresponding to RL).

[0103] The second terminal of the voltage divider module 131 is coupled to the first terminal of the switch module 132.

[0104] The second terminal of the switch module 132 is connected to one terminal of the reset and protection circuit 140.

[0105] The third terminal of the switch module 132 is connected to the other terminal of the reset and protection circuit 140.

[0106] The third terminal of the voltage divider module 131 is connected to the common terminal.

[0107] In some embodiments, the voltage divider module 131 includes a second resistor R102 and a third resistor R103 connected in series.

[0108] Switching module 132 includes a first transistor Q104 and a fourth resistor R104.

[0109] One end of the second resistor R102 is coupled to the source of the second MOSFET Q102.

[0110] The base of the first transistor Q104 is connected to the connection terminals of the second resistor R102 and the third resistor R103.

[0111] The collector of the first transistor Q104 is connected to one end of the reset and protection circuit 140.

[0112] The emitter of the first transistor Q104 is connected to the other end of the reset and protection circuit 140.

[0113] One end of the fourth resistor R104 is connected to the collector of the first transistor Q104.

[0114] The other ends of the third resistor R103 and the fourth resistor R104 are connected to the common terminal.

[0115] Its working principle is as follows:

[0116] The first transistor Q104 is a PNP transistor (a MOSFET can also be used instead of a transistor). The second resistor R102 is connected in parallel between the base and emitter of the first transistor Q104. The second resistor R102 and the third resistor R103 form a voltage divider module 131. Point D is connected to the base of the first transistor Q104 as the voltage divider point. The fourth resistor R104 is connected to the collector of the first transistor Q104. When the first transistor Q104 is turned off, it provides a default pull-down low level to point E. Point E also serves as a low voltage detection signal output to the reset and protection circuit 140 at the back end.

[0117] When the voltage Vc at point C is lower than the set voltage V ref When the voltage Vcd across the second resistor R102 is less than the turn-on voltage of the first transistor Q104, the first transistor Q104 is turned off, and point E is pulled low by the fourth resistor R104.

[0118] When the voltage Vc at point C is higher than the set voltage V ref At that time, the voltage V across the second resistor R102 is cd The turn-on voltage of the first transistor Q104 is clamped, causing the first transistor Q104 to saturate and conduct, and point E is turned on to Vc, and point E becomes high level;

[0119] The setting value of the minimum high-level voltage V ref It can be calculated and set using the following formula, where V TP The turn-on voltage of the first transistor Q104:

[0120]

[0121] In summary, when the voltage at point C is lower than the set voltage, point E is pulled low, indicating that the voltage is too low; when the voltage at point C is higher than the set voltage, point E is pulled high, indicating that the voltage is normal.

[0122] In some embodiments, the reset and protection circuit 140 includes at least a third MOSFET Q103 and a fourth MOSFET Q105, wherein the third MOSFET Q103 is selected as a P-channel MOSFET and the fourth MOSFET Q105 is selected as an N-channel MOSFET, both of which have the function of switching;

[0123] Specifically, the gate of the third MOSFET Q103 and the drain of the fourth MOSFET Q105 are connected to the power supply through the fifth resistor R105.

[0124] The source of the third MOSFET Q103 is connected to the power supply.

[0125] The gate of the fourth MOSFET Q105 is connected to the collector of the first transistor Q104.

[0126] The source of the fourth MOSFET Q105 is connected to the common terminal.

[0127] In some embodiments, the reset and protection circuit 140 further includes a fifth MOSFET Q106, wherein the fifth MOSFET Q106 is selected as an N-channel MOSFET and has the function of a switch;

[0128] Specifically, the gate of the fifth MOSFET Q106 is connected to the reset terminal (RST) of the controller 110.

[0129] The gate of the fifth MOSFET Q106 is also connected to one end of the sixth resistor R106.

[0130] The drain of the fifth MOSFET Q106 is connected to the gate of the third MOSFET Q103 and the drain of the fourth MOSFET Q105, respectively.

[0131] The drain of the fifth MOSFET Q106 is connected to the feedback terminal of the controller 110 (corresponding to V). F )connect,

[0132] The source of the fifth MOSFET Q106 and the other end of the sixth resistor R106 are connected to the common terminal.

[0133] In some embodiments, the reset and protection circuit 140 further includes a first capacitor C101, which has an energy storage function, wherein one end of the first capacitor C101 is connected to one end of the fifth resistor R105.

[0134] The other end of the first capacitor C101 is connected to the common terminal.

[0135] Its working principle is as follows:

[0136] The reset and protection circuit 140 has two inputs and one output, namely the voltage detection result input at point E, the reset signal input at point G, and the self-locking protection signal output at point F;

[0137] The voltage detection result of the low voltage detection circuit 130 is output to the reset and protection circuit 140 through point E. The reset and protection circuit 140 performs self-locking protection measures according to whether the level at point E is high. After triggering the short circuit protection, a high-level signal will be output at point F to indicate that a short circuit has occurred and the self-locking protection has been triggered. After the short circuit fault is cleared, a high-level pulse signal needs to be input through point G to unlock the protection measures and restore normal power supply to the push-pull output circuit 120.

[0138] like Figure 1 As shown, the fourth MOSFET Q105 and the fifth MOSFET Q106 are NMOS transistors, and the third MOSFET Q103 is a PMOS transistor.

[0139] The fifth resistor R105 is a pull-up resistor. In addition to providing a high pull-up level to the gate of the third MOSFET Q103, it also forms an RC startup circuit with the first capacitor C101. At the moment the power supply VCC is powered on, the first capacitor C101 charges and pulls the potential at point F low, so that there is a voltage difference of -VCC between the gate and source of the third MOSFET Q103, causing the third MOSFET Q103 to conduct and pull the voltage at point C high to VCC. The low voltage detection circuit 130 detects that the voltage is normal, and the output level at point E is high, which causes the fourth MOSFET Q105 to conduct, pulling the voltage at point F low to GND, so that the third MOSFET Q103 continues to conduct. At this moment, the self-starting program is completed.

[0140] The sixth resistor R106 provides a default pull-down low level to the gate of the fifth MOSFET Q106. When there is no reset signal input, the fifth MOSFET Q106 remains in the off state. When a reset is required, a high-level pulse signal is input at the RST terminal to turn on the fifth MOSFET Q106 and pull point F low to GND.

[0141] When there is no output short circuit in the push-pull output circuit 120, the output level at point E of the low-voltage detection circuit is high. The fourth MOSFET Q105 conducts, pulling the level at point F low. The third MOSFET Q103 remains on, and VCC normally supplies power to the push-pull output circuit 120 through the third MOSFET Q103. F The low-level output indicates that there is no short circuit in the push-pull output at this moment.

[0142] When a short circuit occurs in the push-pull output circuit 120, the voltage at point C quickly drops below the set voltage value. The output level at point E of the low-voltage detection circuit 130 becomes low, and the fourth MOSFET Q105 turns off, causing the level at point F to be pulled high by the fifth resistor R105. The third MOSFET Q103 then turns off, disconnecting VCC from the push-pull output circuit 120. The voltage at point C becomes 0V, and the voltage at point E remains low. The fourth MOSFET Q105 remains off, and the third MOSFET Q103 also remains off. At this time, the third MOSFET Q103, the first transistor Q104, and the fourth MOSFET Q105 achieve self-locking turn-off. F The high-level output indicates that a short circuit has occurred in the push-pull output at this moment.

[0143] After the short-circuit fault is cleared, a high-level pulse is input to the RST port. The fifth MOSFET Q106 turns on, pulling point F low to the common terminal GND. This causes the third MOSFET Q103 to turn on, restoring the voltage at point C to VCC. The output level at point E of the low-voltage detection circuit becomes high. Consequently, the fourth MOSFET Q105 turns on, pulling the level at point F low. The third MOSFET Q103 remains on, and VCC normally supplies power to the push-pull output circuit 102 through the third MOSFET Q103. F The output remains low.

[0144] This application has at least the following beneficial effects:

[0145] 1. It can detect whether a short circuit has occurred without the need for a series current sensing resistor or Hall element. Since there is no need to connect a current sensing resistor in series with the push-pull output circuit 120, the load effect caused by excessive current is directly avoided.

[0146] 2. The voltage threshold value for low-voltage detection can also be adjusted according to different load requirements by setting the voltage divider resistor of the low-voltage detection circuit 130, so as to flexibly adapt to the needs of various different loads RL.

[0147] 3. The protection and reset circuit also includes a short-circuit fault signal level via V. F The output, the back-end controller 110 can detect V F The voltage level is used to determine whether a short circuit has occurred.

[0148] 4. After the short circuit protection is triggered, the connection between VCC and the push-pull output circuit 120 will be cut off, and it will not recover on its own. This avoids the thermal shock that could damage the switching transistor or power supply if the circuit resumes power supply on its own before the short circuit fault is resolved.

[0149] 5. The protection and reset circuit is equipped with a reset signal terminal RST. After the short circuit fault is cleared, a high-level signal can be output by the back-end drive device or control device to unlock the self-locking protection measures and restore normal power supply.

[0150] 6. The detection and protection circuits do not use expensive chips or other components, but only use common switching transistors and resistors / capacitors to build the circuit, which saves costs and can meet the requirements of applications with low requirements.

[0151] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A short-circuit protected output circuit, characterized in that, have: Controller; A push-pull output circuit, one of its input terminals is connected to one of the output terminals of the controller, for receiving a control signal input by the controller, the control signal being used to trigger the on / off state of the push-pull output circuit; A low-voltage detection circuit, one end of which is connected to the output terminal of the push-pull output circuit, is used to acquire the level signal output by the push-pull output circuit. A reset and protection circuit, one end of which is coupled to the other end of the low-voltage detection circuit, is used to acquire a level signal and output or shut off the power supply to the push-pull output circuit according to the state of the level signal.

2. The short-circuit protection output circuit according to claim 1, characterized in that, When the input control signal is low, the push-pull output circuit outputs a high level to the load. When the input control signal is high, the push-pull output circuit outputs a low level to the load.

3. The short-circuit protection output circuit according to claim 2, characterized in that, The low-voltage detection circuit compares the detected level signal output by the push-pull output circuit with a set value. If the level signal output by the push-pull output circuit is high and the voltage amplitude is lower than the set value, then a low level is output to the reset and protection circuit. If the high-level voltage amplitude of the signal is higher than the set value, a high level is output to the reset and protection circuit. When the low-voltage detection circuit detects that the high-level voltage amplitude is too low, the reset and protection circuit activates protection measures based on the current voltage amplitude, cutting off the connection between the power supply and the push-pull output circuit.

4. The short-circuit protection output circuit according to claim 3, characterized in that, The reset and protection circuit will self-lock after triggering the short-circuit protection, maintaining the disconnection between the power supply and the push-pull output circuit, and feeding back a high level to the controller. The controller determines the output state of the push-pull output circuit based on the input high level.

5. The short-circuit protection output circuit according to any one of claims 1-4, characterized in that, The push-pull output circuit includes a first MOSFET and a second MOSFET. The gates of the first MOSFET and the second MOSFET are connected to an output terminal of the controller. The gates of the first MOSFET and the second MOSFET are also connected to one end of the low-voltage detection circuit through a first resistor. The source of the first MOSFET is connected to the common terminal. The drain of the first MOSFET is connected to the drain of the second MOSFET. The source of the second MOS transistor is connected to one end of the low-voltage detection circuit.

6. The short-circuit protection output circuit according to claim 5, characterized in that, The low-voltage detection circuit includes a voltage divider module and a switching module. The first terminal of the voltage divider module is connected to the source of the second MOS transistor. The second terminal of the voltage divider module is coupled to the first terminal of the switch module. The second terminal of the switch module is connected to one terminal of the reset and protection circuit. The third terminal of the switch module is connected to the other terminal of the reset and protection circuit. The third terminal of the voltage divider module is connected to the common terminal.

7. The short-circuit protection output circuit according to claim 6, characterized in that, The voltage divider module includes a second resistor and a third resistor connected in series. The switching module includes a first transistor and a fourth resistor. One end of the second resistor is coupled to the source of the second MOSFET. The base of the first transistor is connected to the connection terminal of the second resistor and the third resistor. The collector of the first transistor is connected to one end of the reset and protection circuit. The emitter of the first transistor is connected to the other end of the reset and protection circuit. One end of the fourth resistor is connected to the collector of the first transistor. The other ends of the third resistor and the fourth resistor are connected to the common terminal.

8. The short-circuit protection output circuit according to claim 7, characterized in that, The reset and protection circuit includes at least a third MOSFET and a fourth MOSFET. The gate of the third MOS transistor and the drain of the fourth MOS transistor are connected to the power supply through a fifth resistor. The source of the third MOS transistor is connected to the power supply. The gate of the fourth MOS transistor is connected to the collector of the first transistor. The source of the fourth MOS transistor is connected to the common terminal.

9. The short-circuit protection output circuit according to claim 8, characterized in that, The reset and protection circuit also includes a fifth MOSFET. The gate of the fifth MOS transistor is connected to the reset terminal of the controller. The drain of the fifth MOS transistor is connected to the gate of the third MOS transistor and the drain of the fourth MOS transistor, respectively. The drain of the fifth MOSFET is connected to the feedback terminal of the controller. The source of the fifth MOS transistor is connected to the common terminal.

10. The short-circuit protection output circuit according to claim 8, characterized in that, The reset and protection circuit also includes a first capacitor, one end of which is connected to one end of the fifth resistor. The other end of the first capacitor is connected to the common terminal.

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