Enabling circuit and power converter

Abstract

The invention provides an enabling circuit and a power converter, and belongs to the technical field of electronic circuits. The enable circuit comprises a power supply trigger circuit which outputs a break-over voltage; the voltage division circuit is electrically connected to the output end of the power supply trigger circuit, the voltage division circuit comprises a voltage division device, and when the voltage division circuit is turned on for the first time, the turn-on voltage comprises voltage needed by the two ends of the voltage division device; the enabling output circuit is electrically connected to the voltage division circuit, and when the voltage division circuit is switched on, the enabling output circuit is switched on, and an output enabling end is in a high level; the input end of the voltage return circuit is electrically connected to the output enabling end, when the output enabling end is in a high level state, the two output ends of the voltage return circuit are connected with the voltage dividing device in parallel, and the voltage dividing device is short-circuited. According to the enable circuit and the power converter provided by the invention, the anti-interference capability of the enable circuit can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and particularly relates to an enabling circuit and a power converter. Background Art

[0002] The enabling circuit generates a "permission" signal. For some pins of a chip, a single level can form an enabling signal. However, in high-voltage circuits such as the high-voltage auxiliary power supply of an inverter, a separate enabling circuit is provided to form an enabling signal. When the voltage of the voltage source rises to the conduction voltage, a multi-stage control tube is triggered to output an enabling terminal.

[0003] When using a voltage source to trigger a multi-stage control tube, an enabling signal is formed after the voltage rises to the conduction voltage. However, when there are fluctuations in the voltage source, it will cause the output enabling signal to switch back and forth between high and low. The high-voltage auxiliary power supply will also switch on and off repeatedly. Repeated switching of the high-voltage auxiliary power supply within a short period of time may cause hardware damage or a fault to be reported when the system software diagnoses the output voltage. Summary of the Invention

[0004] The purpose of the present invention is to provide an enabling circuit and a power converter, which can enhance the anti-interference ability of the enabling circuit.

[0005] To achieve the above purpose, the present invention provides an enabling circuit, which at least includes:

[0006] A power supply trigger circuit, which outputs a conduction voltage;

[0007] A voltage dividing circuit, electrically connected to the output end of the power supply trigger circuit. The voltage dividing circuit includes a voltage dividing component, and when the voltage dividing circuit is initially conducted, the conduction voltage includes the voltage required across the voltage dividing component;

[0008] An enabling output circuit, electrically connected to the voltage dividing circuit. When the voltage dividing circuit is conducted, the enabling output circuit is conducted, and the output enabling terminal is at a high level; and

[0009] A back-pressure circuit, the input end of the back-pressure circuit is electrically connected to the output enabling terminal. When the output enabling terminal is at a high level, the two output ends of the back-pressure circuit are connected in parallel with the voltage dividing component, and the voltage dividing component is short-circuited.

[0010] In an embodiment of the present invention, the power supply trigger circuit includes a voltage source and a voltage regulating component, and the voltage source and the voltage regulating component are connected in series.

[0011] In an embodiment of the present invention, the voltage regulator device includes a zener diode, a first voltage regulating resistor, and a second voltage regulating resistor. The negative electrode of the zener diode is electrically connected to the positive output terminal of the voltage source through the first voltage regulating resistor, and the positive electrode of the zener diode is electrically connected to the negative output terminal of the voltage source through the second voltage regulating resistor.

[0012] In an embodiment of the present invention, the output voltage of the power supply trigger circuit is obtained by the following formula:

[0013] Vb = (Vin - Vz) * R2 / (R1 + R2);

[0014] Wherein, Vb is the output voltage of the power supply trigger circuit, Vin is the output voltage of the voltage source, Vz is the breakdown voltage of the zener diode, R1 is the resistance value of the first voltage regulating resistor, and R2 is the resistance value of the second regulating resistor.

[0015] In an embodiment of the present invention, the voltage dividing circuit further includes a first control tube. The control end of the first control tube is electrically connected to the output end of the power supply trigger circuit. The first end of the first control tube is electrically connected to the power supply end, and the second end of the first control tube is electrically connected to the ground end through the voltage dividing device.

[0016] In an embodiment of the present invention, when the voltage dividing circuit is initially turned on, the conduction voltage is obtained by the following formula:

[0017] Vt = Vde + Vd;

[0018] Wherein, Vt is the conduction voltage output by the power supply trigger circuit when the voltage dividing circuit is initially turned on, Vde is the forward conduction voltage between the base and emitter of the first control tube, and Vd is the voltage required across the voltage dividing device.

[0019] In an embodiment of the present invention, the voltage dividing device includes a voltage dividing diode, and the positive electrode of the voltage dividing diode is electrically connected to the first control tube, and the negative electrode of the voltage dividing diode is electrically connected to the ground end.

[0020] In an embodiment of the present invention, the voltage dividing device includes two or more voltage dividing diodes, and the two or more voltage dividing diodes are connected in series.

[0021] In an embodiment of the present invention, the voltage dividing device includes at least one zener diode, resistor, or triode.

[0022] In an embodiment of the present invention, the enabling output circuit includes a second control transistor. The control end of the second control transistor is electrically connected to the first end of the first control transistor. The first end of the second control transistor is electrically connected to the power supply terminal, and the second end of the second control transistor is the output enabling end.

[0023] In an embodiment of the present invention, the enabling output circuit further includes:

[0024] A first voltage dividing resistor, one end of the first voltage dividing resistor is electrically connected to the second end of the second control transistor, and the other end of the first voltage dividing resistor is the output enabling end; and

[0025] A second voltage dividing resistor, one end of the second voltage dividing resistor is electrically connected to the other end of the first voltage dividing resistor, and the other end of the second voltage dividing resistor is electrically connected to the ground terminal.

[0026] In an embodiment of the present invention, the enabling output circuit further includes a voltage stabilizing capacitor, and the voltage stabilizing capacitor is connected in parallel with the second voltage dividing resistor.

[0027] In an embodiment of the present invention, the backpressure circuit includes a third control transistor. The control end of the third control transistor is electrically connected to the enabling output end, and the two output ends of the third control transistor are connected in parallel with the two ends of the voltage dividing device.

[0028] In an embodiment of the present invention, the backpressure circuit includes a current limiting resistor. One end of the current limiting resistor is electrically connected to the enabling output end, and the other end of the current limiting resistor is electrically connected to the control end of the third control transistor.

[0029] In an embodiment of the present invention, compared with when the power supply is turned on, the voltage hysteresis when the voltage source is turned off is obtained by the following formula:

[0030] ΔV = Vd * (R1 / R2 + 1);

[0031] Where, ΔV is the voltage hysteresis when the voltage source is turned off and when it is turned on, Vd is the voltage required across the voltage dividing device, R1 is the resistance value of the first voltage regulating resistor, and R2 is the resistance value of the second regulating resistor.

[0032] The present invention also provides a power converter, including the enabling circuit as described above, and the enabling circuit provides an enabling signal for the power converter.

[0033] In summary, the present invention provides an enabling circuit and a power converter. The enabling circuit is an externally enabled circuit with hardware-independent control that can adjust the on-off voltage and hysteresis interval. By setting the backpressure circuit, the conduction voltage required after the enabling circuit is turned on is reduced, enhancing the anti-interference ability of the circuit system. Description of the Drawings

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0035] Figure 1 is the circuit diagram of the enabling circuit in an embodiment of the present application.

[0036] Figure 2 is the voltage timing diagram of the enabling circuit working in an embodiment of the present application. Detailed Embodiments

[0037] To facilitate the understanding of the present application, the following will describe the present application more comprehensively with reference to the relevant accompanying drawings. The preferred embodiments of the present application are shown in the accompanying 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.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0039] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. The degrees indicated by "high" and "low" are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a high or low level, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0040] It should be noted that the control tube adopted in the embodiments of the present invention can use not only a triode, but also a thin film transistor or a field effect transistor or other devices with the same characteristics. In the embodiments of the present invention, to distinguish the connection relationship of the control tube, one pole is called the first end, the other pole is called the second end, and the base is called the control end. In addition, according to the characteristics of the control tube, the control tube can be divided into NPN type and PNP type. In this application, when an NPN type control tube is adopted, the collector of the NPN type control tube is defined as the first end, the emitter of the NPN type control tube is defined as the second end, and when a high level is input to the base, the first end and the second end are turned on. On the contrary, for the PNP type, when a PNP type control tube is adopted, at the initial stage, the emitter of the PNP type control tube is defined as the first end, the collector of the PNP type control tube is defined as the second end, and when a low level is input to the base, the first end and the second end are turned on.

[0041] In a vehicle-mounted device, a high-voltage power supply system is provided to supply power to some key electrical components of the vehicle. The high-voltage power supply system is usually implemented using a high-voltage battery, for example, using a high-voltage battery with an output of 200V to 750V. For the high-voltage power supply system, a power converter is used to convert the high voltage into other voltage signals. In the vehicle, power converters such as an on-board charger (OBC), a direct current / direct current (DC / DC) converter, and a power distribution unit (PDU) are provided. And the power converter circuit needs to input an enable signal, and an external enable circuit independently controlled by hardware needs to be set up to form the enable signal. For this reason, an enable circuit needs to be set up to form the enable signal.

[0042] Please refer to Figure 1As shown in the figure, the present invention provides an enabling circuit that can form a relatively stable enabling signal. The enabling circuit includes a power trigger circuit 100, a voltage dividing circuit 200, an enabling output circuit 300, and a backpressure circuit 400. Among them, a voltage source U1 is provided in the power trigger circuit 100. When the voltage of the voltage source U1 rises to a preset voltage, the output end of the power trigger circuit 100 outputs a conduction voltage as a trigger source. The voltage dividing circuit 200 is electrically connected to the output end of the power trigger circuit 100. A voltage dividing device D1 is provided in the voltage dividing circuit 200. When the voltage dividing circuit 200 is initially conducted, part of the conduction voltage will be divided by the voltage dividing device D1. The enabling circuit is electrically connected to the voltage dividing circuit 200. When the voltage dividing circuit 200 is conducted, it can trigger the enabling output circuit 300 to be electrically connected to the power supply terminal U2, so that the output enabling terminal of the enabling output circuit 300 is at a high level, forming an enabling signal. The input end of the backpressure circuit 400 is electrically connected to the output end of the enabling output circuit 300. When the output enabling terminal of the enabling output circuit 300 is at a high level, the two output ends of the backpressure circuit 400 are connected in parallel with the voltage dividing device D1 in the voltage dividing circuit 200. When the output end of the enabling output circuit 300 has a high level, when the backpressure circuit 400 is triggered, the two output ends of the backpressure circuit 400 are connected in parallel to the voltage dividing device D1, causing the voltage dividing device D1 to be short-circuited. At this time, the voltage required for the voltage dividing circuit 200 to conduct is reduced. Therefore, when there is a small range of source fluctuations in the voltage in the power trigger circuit 100, the voltage dividing circuit 200 will maintain the conducting state, and the enabling signal output by the enabling output circuit 300 will also remain stable, improving the anti-interference ability of the enabling circuit.

[0043] Specifically, please refer to Figure 1 As shown in the figure, in an embodiment of the present invention, the power trigger circuit 100 includes a voltage source U1 and a voltage regulating device, and the voltage regulating device includes a voltage stabilizing device and two voltage regulating resistors. In this embodiment, the voltage regulating device includes a voltage stabilizing diode Z1, a first voltage regulating resistor R1, and a second voltage regulating resistor R2. Among them, the negative electrode of the voltage stabilizing diode Z1 is electrically connected to the positive output end of the voltage source U1 through the first voltage regulating resistor R1, and the positive electrode of the voltage stabilizing diode Z1 is electrically connected to the negative output end of the voltage source U1 through the second voltage regulating resistor R2. That is, one end of the first voltage regulating resistor R1 is electrically connected to the positive output end of the voltage source U1, and the other end of the first voltage regulating resistor R1 is electrically connected to the negative electrode of the voltage stabilizing diode Z1. One end of the second voltage regulating resistor R2 is electrically connected to the negative output end of the voltage source U1, and the other end of the second voltage regulating resistor R2 is electrically connected to the positive electrode of the voltage stabilizing diode Z1.

[0044] Please refer to Figure 1As shown, in an embodiment of the present invention, a zener diode Z1, a first voltage regulating resistor R1, and a second voltage regulating resistor R2 are used to adjust the conduction voltage output by the power supply trigger circuit 100. In this application, the output end of the power supply trigger circuit 100 is the positive pole of the zener diode Z1. If the output voltage of the voltage source U1 gradually increases from zero, when the output voltage of the voltage source U1 is less than the breakdown voltage of the zener diode Z1, the output voltage of the voltage source U1 is applied across the zener diode Z1. When the output voltage of the voltage source U1 is greater than the breakdown voltage of the zener diode Z1, the zener diode Z1, the first voltage regulating resistor R1, and the second voltage regulating resistor R2 divide the output voltage of the voltage source U1. In this application, when the power supply trigger circuit 100 is conducting voltage, the voltage output by the power supply trigger circuit 100 is obtained by the following formula:

[0045] Vb = (Vin - Vz) * R2 / (R1 + R2).

[0046] Wherein, Vb is the output voltage of the power supply trigger circuit, and also the voltage of the base of the first control transistor T1, Vin is the output voltage of the voltage source, Vz is the breakdown voltage of the zener diode, R1 is the resistance value of the first voltage regulating resistor, and R2 is the resistance value of the second regulating resistor.

[0047] Please refer to Figure 1 As shown, in other embodiments of the present invention, a voltage source U1 and other voltage regulating components can also be used to adjust the conduction voltage output by the power supply trigger circuit 100. In some embodiments, it can be achieved by only using the voltage source U1 and a plurality of resistors connected in series. In other embodiments, it can be achieved by connecting the voltage source U1, a diode, and a plurality of resistors connected in series. In still other embodiments, it can be achieved by using the voltage source U1 and a plurality of series-connected zener diodes and resistors. This application does not limit the form of the voltage regulating components in the power supply trigger circuit 100, as long as the voltage regulating function is achieved.

[0048] Please refer to Figure 1 As shown, in an embodiment of the present invention, the voltage dividing circuit 200 includes a first control transistor T1 and a voltage dividing component D1. Among them, the control end of the first control transistor T1 is electrically connected to the output end of the power supply trigger circuit 100, the first end of the first control transistor T1 is electrically connected to the power supply terminal U2, the second end of the first control transistor T1 is electrically connected to one end of the voltage dividing component D1, and the other end of the voltage dividing component D1 is electrically connected to the ground terminal GND. That is, the second end of the first control transistor T1 is electrically connected to the ground terminal GND through the voltage dividing component D1. In this application, when there is no voltage signal at the output end of the power supply trigger circuit 100, that is, when there is no input voltage at the control end of the first control transistor T1, the first control transistor T1 is in an off state. When the voltage output by the output end of the power supply trigger circuit 100 reaches the conduction voltage, the first control transistor T1 conducts.

[0049] Please refer to Figure 1 As shown, in an embodiment of the present invention, the first control transistor T1 is implemented by using an NPN bipolar junction transistor. At this time, the base of the first control transistor T1 is electrically connected to the output terminal of the power trigger circuit 100, the collector of the first control transistor T1 is electrically connected to the power supply terminal U2, and the emitter of the first control transistor T1 is electrically connected to the ground terminal GND through the voltage divider device D1. The voltage divider device D1 is implemented by using a diode. Therefore, in this embodiment, when the first control transistor T1 is turned on, the magnitude of the turn-on voltage is obtained by the following formula:

[0050] Vt = Vde + Vd;

[0051] where Vt is the turn-on voltage output by the power trigger circuit when the voltage divider circuit is initially turned on, Vde is the forward turn-on voltage between the base and emitter of the first control transistor T1, and Vd is the voltage required across the voltage divider device.

[0052] It should be noted that the present application does not limit the specific form of the first control transistor T1. The first control transistor T1 is implemented to be turned off when the control terminal is at a low level and turned on when the voltage at the control terminal reaches the turn-on voltage. In other embodiments, the first control transistor T1 can also be implemented by using transistors such as thin-film transistors or field-effect transistors.

[0053] Please refer to Figure 1 As shown, in an embodiment of the present invention, a first current-limiting resistor R3 is further provided between the control terminal of the first control transistor T1 and the output terminal of the power trigger circuit 100. That is, one end of the first current-limiting resistor R3 is electrically connected to the output terminal of the power trigger circuit 100, and the other end is electrically connected to the control terminal of the first control transistor T1. The first current-limiting resistor R3 can limit the current flowing into the control terminal of the first control transistor T1 and prevent damage to the control terminal of the first control transistor T1 caused by a large current. A second current-limiting resistor R4 is further provided between the first control transistor T1 and the power supply terminal U2. That is, one end of the second current-limiting resistor R4 is electrically connected to the power supply terminal U2, and the other end is electrically connected to the first end of the first control transistor T1. When the first control transistor T1 is turned on, the second current-limiting resistor R4, the voltage divider device D1, and the turned-on first control transistor T1 are connected in series. It can limit the current flowing through the first control transistor T1 and prevent damage to the first control transistor T1 and the voltage divider device D1.

[0054] Please refer to Figure 1As shown, the present application does not limit the specific form of the voltage divider device D1. The voltage divider device D1 can achieve the voltage division function. In other embodiments, the voltage divider device D1 can also be implemented by one, two or more voltage stabilizing diodes, resistors or triodes and other electrical components. When using a triode as the voltage divider device, it is implemented by using the diode between the base and the emitter of the triode, and the collector can be left floating during use. Since when the first control transistor T1 is turned on, the second current limiting resistor R4 will be connected in series with the voltage divider device D1, the parameters of the second current limiting resistor R4 and the voltage divider device D1 can be set according to the voltage of the power supply terminal U2 and the magnitude of the voltage division required by the voltage divider device D1.

[0055] Please refer to Figure 1 As shown, when it is necessary to adjust the voltage across the voltage divider device D1 to adjust the voltage hysteresis of the enabling circuit. For example, if it is necessary to increase the voltage hysteresis of the enabling circuit, one diode can be replaced by two or more diodes connected in series. Of course, one diode can also be replaced by two or more voltage stabilizing diodes connected in series.

[0056] Please refer to Figure 1 As shown, in an embodiment of the present invention, the enabling output circuit 300 includes a second control transistor T2. The control terminal of the second control transistor T2 is electrically connected to one end of the first control transistor T1 that is electrically connected to the power supply terminal U2. The first end of the second control transistor T2 is electrically connected to the power supply terminal U2, and the second end of the second control transistor T2 is the output enabling terminal EN. In the present application, when the first control transistor T1 is turned off, there is no input at the control terminal of the second control transistor T2, and the voltage difference between the emitter and the base of the second control transistor T2 is zero, and the second control transistor T2 is in the off state. When the first control transistor T1 is turned on, there is an input at the control terminal of the second control transistor T2, and there is a voltage difference between the emitter and the base of the second control transistor T2, and the second control transistor T2 is turned on. When the second control transistor T2 is turned on, the output enabling terminal EN located at the second end of the second control transistor T2 outputs a high level.

[0057] Please refer to Figure 1 As shown, in an embodiment of the present invention, the second control transistor T2 is implemented by using a PNP type triode. At this time, the base of the second control transistor T2 is electrically connected to the output terminal of the power supply trigger circuit 100, the collector of the second control transistor T2 is electrically connected to the power supply terminal U2, and the emitter of the second control transistor T2 is electrically connected to the ground terminal GND through the voltage divider device D1.

[0058] It should be noted that the present application does not limit the specific form of the second control transistor T2. The second control transistor T2 can be implemented to be turned off when the control terminal is at a high level and turned on when at a low level. In other embodiments, the second control transistor T2 can also be implemented by using transistors such as thin film transistors or field effect transistors.

[0059] Please refer to Figure 1As shown, in an embodiment of the present invention, a third current-limiting resistor R5 is further provided between the control terminals of the first control transistor T1 and the second control transistor T2. One end of the third current-limiting resistor R5 is electrically connected to the common terminal of the first control transistor T1 and the second current-limiting resistor R4, and the other end is electrically connected to the control terminal of the second control transistor T2. The third current-limiting resistor R5 can limit the current flowing into the control terminal of the second control transistor T2, avoiding damage to the control terminal of the second control transistor T2 caused by a large current.

[0060] Please refer to Figure 1 As shown, in an embodiment of the present invention, two series-connected voltage-dividing resistors are further provided at the second end of the second control transistor T2, and the output enable terminal EN of the enable output circuit 300 is located at the common terminal of the two voltage-dividing resistors. Specifically, the two series-connected voltage-dividing resistors include a first voltage-dividing resistor R6 and a second voltage-dividing resistor R7. One end of the first voltage-dividing resistor R6 is electrically connected to the output terminal of the second control transistor T2, the other end of the first voltage-dividing resistor R6 is the output enable terminal EN, one end of the second voltage-dividing resistor R7 is electrically connected to the other end of the first voltage-dividing resistor R6, and the other end of the second voltage-dividing resistor R7 is electrically connected to the ground terminal GND. When the second control transistor T2 is turned on, the second control transistor T2, the first voltage-dividing resistor R6, and the second voltage-dividing resistor R7 are connected in series between the power supply terminal U2 and the ground terminal GND. When the output enable terminal EN needs to match different auxiliary source control chips, the voltage of the output enable terminal EN can be adjusted by adjusting the magnitudes of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7.

[0061] Please refer to Figure 1 As shown, in an embodiment of the present invention, a voltage-stabilizing capacitor C1 is further provided in the enable output circuit 300, and the voltage-stabilizing capacitor C1 is connected in parallel with the second voltage-dividing resistor R7. Since the voltage of the output enable terminal EN of the enable output circuit 300 is equal to the voltage across the second voltage-dividing resistor R7, when there is interference in the circuit, the voltage-stabilizing capacitor C1 can filter the enable signal output, making the output enable signal more stable.

[0062] Please refer to Figure 1As shown, in an embodiment of the present invention, the backpressure circuit 400 includes a third control transistor T3. The control end of the third control transistor T3 is electrically connected to the output enable terminal EN. The two output ends of the third control transistor T3 are connected in parallel across both ends of the voltage divider device D1. And the first end of the third control transistor T3 is electrically connected to the common end of the voltage divider device D1 and the first control transistor T1. The second end of the third control transistor T3 is electrically connected to the ground terminal GND. In an embodiment of the present invention, the third control transistor T3 is implemented by using an NPN-type triode. At this time, the base of the third control transistor T3 is electrically connected to the common end of the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7. The collector of the third control transistor T3 is electrically connected to the common end of the first control transistor T1 and the voltage divider device D1. The emitter of the third control transistor T3 is electrically connected to the common end of the voltage divider device D1 and the ground terminal GND.

[0063] It should be noted that the present application does not limit the specific form of the third control transistor T3. The third control transistor T3 is implemented to be turned off when the control end is at a low level and turned on when at a high level. In other embodiments, the third control transistor T3 can also be implemented by using transistors such as thin-film transistors or field-effect transistors.

[0064] Please refer to Figure 1 As shown, in an embodiment of the present invention, when the third control transistor T3 is turned on, the voltage divider device D1 is short-circuited. The first control transistor T1 is electrically connected to the ground terminal GND through the third control transistor T3. At this time, since the voltage divider device D1 is short-circuited, the conduction voltage required by the first control transistor T1 will decrease. Specifically, the conduction voltage Vt when the first control transistor T1 is turned on is equal to the forward conduction voltage Vde between the base and the emitter of the first control transistor T1, and there is a hysteresis compared with the initial conduction voltage of the first control transistor T1. Therefore, compared with when starting up, the voltage hysteresis of the first control transistor T1 when shutting down is equal to the voltage Vd required across both ends of the voltage divider device. At this time, if the voltage of the voltage source U1 fluctuates within a small range, it will not affect the output of the output enable terminal EN.

[0065] Please refer to Figure 1 As shown, in an embodiment of the present invention, a fourth current-limiting resistor R8 is further provided between the third control transistor T3 and the output enable terminal EN. One end of the fourth current-limiting resistor R8 is electrically connected to the output enable terminal EN, and the other end is electrically connected to the control end of the third control transistor T3. It can limit the current flowing into the control end of the third control transistor T3 and avoid damage to the control end of the third control transistor T3 caused by a large current.

[0066] Please refer to Figure 1 and Figure 2As shown, in an embodiment of the present invention, an enabling signal is generated using an enabling circuit provided in this application. Before the input voltage of the voltage source U1 rises to the moment t0, the voltage regulator device Z1 is not broken down. At the moment t0, the input voltage Vin of the voltage source U1 reaches the breakdown voltage Vz of the voltage regulator device Z1. At this time, the voltage Vb at the control end of the first control transistor T1 is equal to 0, where Vb is the voltage of the base of the first control transistor T1 with respect to the ground.

[0067] Please refer to Figure 1 and Figure 2 As shown, if the input voltage Vin of the voltage source U1 continues to rise, the voltage across the second voltage regulating resistor R2 (the output voltage of the voltage dividing circuit 200) linearly increases, which is (Vin - Vz) * R2 / (R1 + R2). At this time, the voltage Vb at the control end of the first control transistor T1 also continues to rise. At the moment t2, the voltage Vb at the control end of the first control transistor T1 reaches the forward conduction voltage Vde from the base to the emitter of the first control transistor T1 plus the forward conduction voltage Vd of the voltage regulator device D1. That is, when the voltage Vb at the control end of the first control transistor T1 reaches V3, the first control transistor T1 conducts, and the voltage of the collector of the first control transistor T1 with respect to the ground drops from the voltage Vcc of the power supply terminal U2 to 0. At this time, the PN junction between the emitter and the base of the second control transistor T2 conducts, the second control transistor T2 conducts, and the output enable terminal EN of the output enabling circuit 300 changes from 0 to a high level. This high-level enabling signal can be sent to the auxiliary power control chip to control the working state of the auxiliary power supply. And the voltage of the enabling signal can be obtained through the following formula:

[0068] Ven = Vcc * R6 / (R6 + R7);

[0069] where, Ven is the voltage of the enabling signal, R6 is the resistance value of the first voltage dividing resistor, and R7 is the resistance value of the second voltage dividing resistor.

[0070] Please refer to Figure 1 and Figure 2 As shown, when the output enable terminal EN of the output enabling circuit 300 changes from 0 to a high level, the high-level signal of the output enable signal EN will pass through the fourth current limiting resistor R8 and be sent to the control end of the third control transistor T3. Then the third control transistor T3 conducts. After the third control transistor T3 conducts, it will short-circuit the voltage dividing device D1, and the voltage Vb at the control end of the first control transistor T1 will drop from (Vde + Vd) to Vde, that is, the voltage Vb at the control end of the first control transistor T1 drops to V4. This makes the shutdown voltage of the voltage source U1 drop from Vz + (Vde + Vd) * (R1 / R2 + 1) to Vz + (Vde) * (R1 / R2 + 1), and there is a voltage hysteresis compared with the startup voltage Vz + (Vde + Vd) * (R1 / R2 + 1). Therefore, compared with the startup, the voltage hysteresis of the voltage source U1 when shutting down can be obtained through the following formula:

[0071] ΔV = Vd * (R1 / R2 + 1);

[0072] Where, ΔV is the voltage hysteresis when the voltage source is turned off and on, Vd is the voltage required across the voltage divider component, R1 is the resistance value of the first voltage regulating resistor, and R2 is the resistance value of the second regulating resistor.

[0073] Please refer to Figure 1 and Figure 2 As shown, in an embodiment of the present invention, when the input voltage Vin of the voltage source U1 drops, the voltage across the second voltage regulating resistor R2 drops linearly with the input voltage. When the voltage Vd at the control terminal of the first control transistor T1 drops below the conduction voltage drop Vde between the base and emitter of the triode, that is, when the voltage of the voltage source U1 drops below V2, the third control transistor T3 starts to change from saturation to cut-off, which causes the third control transistor T3 and the second control transistor T2 to turn off, thereby cutting off the voltage at the output enable terminal EN and making it a low level. It can be seen from the waveform schematic diagram that there is a hysteresis interval between the enable turn-on voltage and the turn-off voltage of this circuit, and the voltage difference in this interval is approximately the forward conduction voltage drop of the voltage divider component D1, and this conduction voltage drop is equal to the difference between V3 and V4. The input voltage points of the voltage source U1 corresponding to the output enable terminal at V3 and V4 are V1 and Vz respectively. Therefore, by adjusting the resistors R1 and R2 and the forward conduction voltage drop of the voltage divider component D1, the hysteresis interval of the input voltage can be adjusted.

[0074] In summary, the present invention provides an enable circuit and a power converter. A power trigger circuit, a voltage dividing circuit, an enable output circuit, and a back voltage circuit are provided in the enable circuit. The voltage dividing circuit among them is electrically connected to the output terminal of the power trigger circuit, and a voltage divider component is provided in the voltage dividing circuit. The enable output circuit is electrically connected to the voltage dividing circuit. When the voltage dividing circuit conducts, the enable output circuit conducts and the output enable terminal is at a high level. The input terminal of the back voltage circuit is electrically connected to the output enable terminal. When the output enable terminal is at a high level, the two output terminals of the back voltage circuit are connected in parallel with the voltage divider component, and the voltage divider component is short-circuited, so that the turn-off voltage of the enable circuit is less than the turn-on voltage. Through the enable circuit and power converter provided by the present invention, the anti-interference ability of the enable circuit can be improved.

[0075] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the relevant technical field can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An enabling circuit, characterized in that, At least including: A power trigger circuit that outputs a conduction voltage; A voltage dividing circuit electrically connected to the output end of the power trigger circuit. The voltage dividing circuit includes a voltage dividing component, and when the voltage dividing circuit is initially conducted, the conduction voltage includes the voltage required across the voltage dividing component; An enable output circuit electrically connected to the voltage dividing circuit. When the voltage dividing circuit is conducted, the enable output circuit is conducted and the output enable terminal is at a high level; and A backpressure circuit. The input end of the backpressure circuit is electrically connected to the output enable terminal. When the output enable terminal is at a high level, the two output ends of the backpressure circuit are connected in parallel with the voltage dividing component, and the voltage dividing component is short-circuited.

2. The enabling circuit according to claim 1, characterized in that, The power trigger circuit includes a voltage source and a voltage regulating component, and the voltage source and the voltage regulating component are connected in series.

3. The enabling circuit according to claim 2, wherein The voltage regulating component includes a zener diode, a first voltage regulating resistor, and a second voltage regulating resistor. The negative electrode of the zener diode is electrically connected to the positive output end of the voltage source through the first voltage regulating resistor, and the positive electrode of the zener diode is electrically connected to the negative output end of the voltage source through the second voltage regulating resistor.

4. The enabling circuit according to claim 3, characterized in that, The output voltage of the power trigger circuit is obtained by the following formula: Vb = (Vin - Vz) * R2 / (R1 + R2); Wherein, Vb is the output voltage of the power trigger circuit, Vin is the output voltage of the voltage source, Vz is the breakdown voltage of the zener diode, R1 is the resistance value of the first voltage regulating resistor, and R2 is the resistance value of the second regulating resistor.

5. The enabling circuit according to claim 1, characterized in that The voltage dividing circuit further includes a first control tube. The control end of the first control tube is electrically connected to the output end of the power trigger circuit. The first end of the first control tube is electrically connected to the power supply end, and the second end of the first control tube is electrically connected to the ground end through the voltage dividing component.

6. An enabling circuit according to claim 5, characterized in that, When the voltage dividing circuit is initially conducted, the conduction voltage is obtained by the following formula: Vt = Vde + Vd; Wherein, Vt is the conduction voltage output by the power trigger circuit when the voltage dividing circuit is initially conducted, Vde is the forward conduction voltage between the base and emitter of the first control tube, and Vd is the voltage required across the voltage dividing component.

7. An enabling circuit according to claim 5, characterized in that, The voltage dividing component includes a voltage dividing diode, and the positive electrode of the voltage dividing diode is electrically connected to the first control tube, and the negative electrode of the voltage dividing diode is electrically connected to the ground end.

8. An enabling circuit according to claim 1, wherein, The voltage dividing component includes two or more voltage dividing diodes, and the two or more voltage dividing diodes are connected in series.

9. The enabling circuit according to claim 1, characterized in that, The voltage dividing component includes at least one zener diode, resistor, or triode.

10. An enabling circuit according to claim 5, wherein, The enable output circuit includes a second control tube. The control end of the second control tube is electrically connected to the first end of the first control tube. The first end of the second control tube is electrically connected to the power supply end, and the second end of the second control tube is the output enable terminal.

11. An enabling circuit according to claim 10, characterized in that, The enable output circuit further includes: A first voltage dividing resistor. One end of the first voltage dividing resistor is electrically connected to the second end of the second control tube, and the other end of the first voltage dividing resistor is the output enable terminal; and A second voltage-dividing resistor, one end of the second voltage-dividing resistor is electrically connected to the other end of the first voltage-dividing resistor, and the other end of the second voltage-dividing resistor is electrically connected to the ground terminal.

12. An enabling circuit according to claim 11, wherein, The enabling output circuit further includes a voltage stabilizing capacitor, and the voltage stabilizing capacitor is connected in parallel with the second voltage-dividing resistor.

13. The enabling circuit according to claim 1, characterized in that, The back voltage circuit includes a third control transistor, a control end of the third control transistor is electrically connected to the enabling output end, and two output ends of the third control transistor are connected in parallel with two ends of the voltage dividing component.

14. An enabling circuit according to claim 13, characterized in that, The back voltage circuit includes a current limiting resistor, one end of the current limiting resistor is electrically connected to the enabling output end, and the other end of the current limiting resistor is electrically connected to the control end of the third control transistor.

15. An enabling circuit according to claim 3, wherein, Compared with when the power is turned on, the voltage hysteresis when the voltage source is turned off is obtained by the following formula: ΔV = Vd * (R1 / R2 + 1); Wherein, ΔV is the voltage hysteresis when the voltage source is turned off and when it is turned on, Vd is the required voltage across the voltage dividing component, R1 is the resistance value of the first voltage regulating resistor, and R2 is the resistance value of the second regulating resistor.

16. A power converter, characterized in that, It includes the enabling circuit according to claim 1, and the enabling circuit provides an enabling signal for the power converter.

Images