Slow start circuit and electronic equipment

Abstract

The utility model provides a slow start circuit and electronic equipment. The slow start circuit comprises a switch tube and a signal generation circuit, a first communication end of the switch tube is used for accessing a first power supply signal, and a second communication end of the switch tube is used for connecting a load; the signal generation circuit is connected with the control end of the switch tube and is used for accessing a second power supply signal and providing an electric signal of which the voltage value changes along with time for the control end of the switch tube based on the second power supply signal so as to control the switch tube to be slowly conducted; wherein the voltage value of the first power supply signal is smaller than that of the second power supply signal. The slow start circuit provided by the utility model can improve the utilization rate of the power supply.

Description

Technical Field

[0001] This application relates to the field of electronic technologies, and particularly to a soft-start circuit and an electronic device. Background Art

[0002] In existing power supplies, a large current pulse is generated instantaneously when the power supply is powered on and started. The large current pulse may not only damage the load or the upper-level power supply device, but also cause electromagnetic compatibility problems, thereby interfering with other electronic components in the circuit. Therefore, a soft-start circuit needs to be set up in many application scenarios of the power supply. For example, with the rapid development of new energy vehicles and electric vehicles, the degree of electronicization of vehicles is getting higher and higher, and the high-power electrical equipment on the vehicle is gradually increasing. When the vehicle starts, the power supply of the high-power electrical equipment generates a large current pulse instantaneously when it is powered on. On the one hand, the large current pulse will cause the upper-level power distribution network to trigger a wrong judgment and disconnect the power supply of the load, resulting in the load being unable to work properly due to lack of power supply; on the other hand, the instantaneous change of the current will cause electromagnetic compatibility problems.

[0003] In the existing soft-start circuit, the characteristic that the resistance of the thermistor is relatively large at the initial start is used to reduce the current pulse at the start. However, when a relatively large current passes through the load after the start is completed, there will be a relatively large voltage drop across the thermistor, resulting in low utilization rate of the power supply. Summary of the Utility Model

[0004] This application provides a soft-start circuit and an electronic device, which can improve the utilization rate of the power supply.

[0005] This application provides a soft-start circuit, which includes a switching tube and a signal generation circuit. The first communication terminal of the switching tube is used to access a first power supply signal, and the second communication terminal of the switching tube is used to connect to a load; the signal generation circuit is connected to the control terminal of the switching tube, and is used to access a second power supply signal and provide an electrical signal with a voltage value that changes with time to the control terminal of the switching tube based on the second power supply signal to control the switching tube to conduct slowly; wherein, the voltage value of the first power supply signal is less than the voltage value of the second power supply signal.

[0006] In one embodiment, the soft-start circuit further includes a first power supply terminal and a second power supply terminal. The first power supply terminal is connected to the first communication terminal of the switching tube and accesses the first power supply signal, and the second power supply terminal is connected to the signal generation circuit and accesses the second power supply signal.

[0007] In one embodiment, the switching tube includes an N-type MOS tube.

[0008] In one embodiment, the signal generation circuit includes a constant current circuit and a storage capacitor. The constant current circuit is connected to a second power supply signal. One end of the storage capacitor is connected to the constant current circuit and the control end of the switching transistor, and the other end of the storage capacitor is grounded. Wherein, the storage capacitor provides an electrical signal with a voltage value varying with time to the control end of the switching transistor based on the constant current electrical signal of the constant current circuit.

[0009] In one embodiment, the constant current circuit includes a first resistor, a first switching transistor, a second switching transistor, and a second resistor. One end of the first resistor is used to connect to the second power supply signal. The first end of the first switching transistor is connected to one end of the first resistor, and the control end of the first switching transistor is connected to the other end of the first resistor. The first end of the second switching transistor is connected to the control end of the first switching transistor and the other end of the first resistor. The second end of the second switching transistor is connected to one end of the storage capacitor and the control end of the switching transistor, and the control end of the second switching transistor is connected to the second end of the first switching transistor. One end of the second resistor is connected to the control end of the second switching transistor and the second end of the first switching transistor, and the other end of the second resistor is grounded.

[0010] In one embodiment, the signal generation circuit further includes a first zener diode. The cathode of the first zener diode is connected to one end of the storage capacitor, and the anode of the first zener diode is grounded.

[0011] In one embodiment, the soft start circuit further includes a second zener diode and a third resistor. The anode of the second zener diode is connected to the second communication end of the switching transistor, and the cathode of the second zener diode is connected to the control end of the switching transistor. Both ends of the third resistor are respectively connected to the second communication end and the control end of the switching transistor.

[0012] In one embodiment, the soft start circuit further includes a filter circuit, and the filter circuit is connected to the second communication end of the switching transistor.

[0013] In one embodiment, the soft start circuit further includes a bootstrap boost circuit. The bootstrap boost circuit is connected to the signal generation circuit and is used to provide the second power supply signal.

[0014] This application provides an electronic device, and the electronic device includes the above-mentioned soft start circuit.

[0015] The beneficial effects of this application are as follows: The soft start circuit provided by this application includes a signal generation circuit of a switching transistor. Wherein, the first communication end of the switching transistor is connected to a first power supply signal, and the signal generation circuit provides an electrical signal with a voltage value varying with time to the control end of the switch based on the second power supply signal, so that the switching transistor can be slowly turned on over time, thereby reducing the pulsed current and further improving the electromagnetic compatibility problem. In addition, when the switching transistor is fully turned on and passing a large current, the voltage drop between the first communication end and the second communication end of the switching transistor is almost 0, which can improve the power supply utilization rate. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present application, 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 application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings, where:

[0017] Figure 1 is a schematic structural diagram of an embodiment of the soft-start circuit provided by the present application;

[0018] Figure 2 is a schematic circuit diagram of an embodiment of the soft-start circuit provided by the present application;

[0019] Figure 3 is a schematic structural diagram of an embodiment of the electronic device provided by the present application. Detailed Embodiments

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0021] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present application, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0022] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0023] Refer to Figure 1 and Figure 2 , Figure 1 is a schematic structural diagram of an embodiment of the soft-start circuit provided by the present application; Figure 2It is a schematic circuit diagram of an embodiment of the soft-start circuit provided by the present application. The soft-start circuit 10 includes a switching transistor 110 and a signal generation circuit 120. Among them, the first communication terminal of the switching transistor 110 is used to access the first power supply signal VCC1, and the second communication terminal of the switching transistor 110 is used as the output terminal VOUT to connect to a load and output the first power supply signal VCC1; the signal generation circuit 120 is connected to the control terminal of the switching transistor 110, and is used to access the second power supply signal VCC2, and based on the second power supply signal VCC2, provide an electrical signal with a voltage value that changes over time to the control terminal of the switching transistor 110 to control the slow conduction of the switching transistor 110; among them, the voltage value of the first power supply signal VCC1 is less than the voltage value of the second power supply signal VCC2.

[0024] Among them, both the first power supply signal VCC1 and the second power supply signal VCC2 are DC electrical signals. It can be known that the first power supply signal VCC1 and the second power supply signal VCC2 are respectively input to the switching transistor 110 and the signal generation circuit 120, and the signal generation circuit 120 generates an electrical signal with a voltage value that increases over time based on the second power supply signal VCC2. Therefore, the electrical signal at the control terminal of the switching transistor 110 increases over time, causing the switching transistor 110 to conduct slowly over time, thereby reducing the pulsed current and enhancing the usage safety of the load. In addition, since the voltage value of the second power supply signal VCC2 is greater than the voltage value of the first power supply signal VCC1, after the switching transistor 110 is turned on, the voltage value at the control terminal is close to the voltage value of the second power supply signal VCC2, that is, the voltage between the control terminal and the second communication terminal of the switching transistor 110 is stabilized at the difference between the voltage value of the second power supply signal VCC2 and the voltage value of the first power supply signal VCC1. When the switching transistor 110 passes a large current, the voltage drop between the first communication terminal and the second communication terminal of the switching transistor 110 is almost 0.

[0025] The soft-start circuit 10 provided by the present application includes the signal generation circuit 120 of the switching transistor 110. Among them, the first communication terminal of the switching transistor 110 accesses the first power supply signal VCC1, and the signal generation circuit 120 provides an electrical signal with a voltage value that changes over time to the control terminal of the switch based on the second power supply signal VCC2, so that the switching transistor 110 can conduct slowly over time, thereby reducing the pulsed current and improving the electromagnetic compatibility problem; in addition, when the switching transistor 110 is fully turned on and the switching transistor 110 passes a large current, the voltage drop between the first communication terminal and the second communication terminal of the switching transistor 110 is almost 0, which can improve the utilization rate of the power supply.

[0026] Among them, the signal generation circuit 120 can be an integrated signal generation chip. For example, it uses a digital-to-analog conversion circuit or a digital-to-analog conversion module to output an electrical signal whose voltage value slowly increases with time. Alternatively, the signal generation circuit 120 includes a circuit composed of a power storage element, and uses the characteristic that the voltage slowly increases with time during the charging process of the power storage element to output an electrical signal whose voltage value slowly increases with time. There is no limitation here.

[0027] In one embodiment, the switching transistor 110 includes an N-type MOS transistor. Compared with switching transistors of the same electrical specifications, the N-type MOS transistor has a smaller volume and a lower price. In addition, the on-resistance of the N-type MOS transistor can be made smaller. Therefore, after the switching transistor 110 is fully turned on, the on-resistance is in the minimum state, and the voltage drop of the switching transistor 110 when passing a large current is the smallest, and the utilization rate of the power supply is higher.

[0028] In one embodiment, continue to refer to Figure 1 or Figure 2 , the soft-start circuit 10 further includes a first power supply terminal 130 and a second power supply terminal 140. Among them, the first power supply terminal 130 is connected to the first communication terminal of the switching transistor 110, and the first power supply terminal 130 is used to access a first power supply signal VCC1. The second power supply terminal 140 is connected to the signal generation circuit 120, and the second power supply terminal 140 is used to access a second power supply signal VCC2. The soft-start circuit 10 of this embodiment is provided with the first power supply terminal 130 and the second power supply terminal 140 to access the first power supply signal VCC1 and the second power supply signal VCC2 respectively, so that the switching transistor 110 maintains a stable on state after being turned on, enhancing the on stability of the switching transistor 110, thereby enhancing the stability of the soft-start circuit 10.

[0029] Among them, the power supplies accessed by the first power supply terminal 130 and the second power supply terminal 140 can be the same, such as a power supply circuit that can output power supply signals with different voltage values; or the power supplies accessed by the first power supply terminal 130 and the second power supply terminal 140 are different. For example, the first power supply terminal 130 accesses a first power supply circuit that outputs a first power supply signal VCC1, and the second power supply terminal 140 accesses a second power supply circuit that outputs a second power supply signal VCC2. There is no limitation here.

[0030] In one embodiment, continue to refer to Figure 1 , the soft-start circuit 10 further includes a filtering circuit 160, and the filtering circuit 160 is connected to the second communication terminal of the switching transistor 110. Among them, the filtering circuit 160 is used to filter out interference signals, such as filtering out current pulse signals after the switching transistor 110 is turned on, and can improve the electromagnetic compatibility problem of the soft-start circuit 10.

[0031] In one implementation, the filter circuit 160 includes a filter capacitor C61. The filter capacitor C61 can be used to filter out current pulse signals and improve the electromagnetic compatibility problem of the soft start circuit 10. In addition, the filter capacitor C61 can not only be used for filtering, but also for implementing a storage function.

[0032] In one embodiment, the soft start circuit 10 further includes a bootstrap boost circuit (not labeled in the figure). The bootstrap boost circuit is connected to the signal generation circuit 120 and is used to provide a second power supply signal VCC2. The bootstrap boost circuit can be an integrated power conversion circuit or a conventional boost circuit, which is not limited herein. The bootstrap boost circuit of this embodiment can output the second power supply signal VCC2 based on the first power supply signal VCC1 or other power supply signals to provide a second power supply signal VCC2 with a voltage value greater than the first power supply signal VCC1. After the switching transistor 110 is turned on, a stable second power supply signal VCC2 is still provided, so that the switching transistor 110 can maintain a stable on state after being turned on, which can enhance the on stability of the switching transistor 110, thereby enhancing the stability of the soft start circuit 10.

[0033] In one embodiment, continue to refer to Figure 1 , the signal generation circuit 120 includes a constant current circuit 121 and a storage capacitor 122. The constant current circuit 121 accesses the second power supply signal VCC2 through the second power supply terminal 140 and outputs a constant current signal based on the second power supply signal VCC2. One end of the storage capacitor 122 is connected to the constant current circuit 121 and the control terminal of the switching transistor 110, and the other end of the storage capacitor 122 is grounded to GND. The storage capacitor 122 provides an electrical signal with a voltage value varying with time to the control terminal of the switching transistor 110 based on the constant current signal of the constant current circuit 121. It can be known that the constant current circuit 121 outputs a constant current signal based on the second power supply signal VCC2, and the constant current signal charges the storage capacitor 122, so that the storage capacitor 122 outputs an electrical signal with a voltage value increasing with time to the control terminal of the switching transistor 110, so that the switching transistor 110 can be slowly turned on. By adjusting the value of the constant current signal of the constant current circuit 121 and / or the capacitance of the storage capacitor 122, the duration required for the switching transistor 110 to turn from off to on can be adjusted, realizing the slow turn-on of the switching transistor 110.

[0034] The signal generation circuit 120 of this embodiment includes a constant current circuit 121 and a storage capacitor 122, which has a simple structure and a simple process for controlling the switching transistor 110 to turn on, and is easy to implement.

[0035] In one embodiment, the constant current circuit 121 includes an integrated constant current chip, and the integrated constant current chip can enhance the stability of the signal generation circuit 120.

[0036] In one embodiment, the constant current circuit 121 includes a first resistor R21, a first switching transistor Q21, a second switching transistor Q22, and a second resistor R22. One end of the first resistor R21 is used to connect to the second power supply signal VCC2; the first end of the first switching transistor Q21 is connected to one end of the first resistor R21, and the control end of the first switching transistor Q21 is connected to the other end of the first resistor R21; the first end of the second switching transistor Q22 is connected to the control end of the first switching transistor Q21 and the other end of the first resistor R21, the second end of the second switching transistor Q22 is connected to one end of the energy storage capacitor 122 and the control end of the switching transistor 110, and the control end of the second switching transistor Q22 is connected to the second end of the first switching transistor Q21; one end of the second resistor R22 is connected to the control end of the second switching transistor Q22 and the second end of the first switching transistor Q21, and the other end of the second resistor R22 is grounded to GND.

[0037] Among them, the second power supply signal VCC2 is input to the constant current circuit 121. At this time, the constant current circuit 121 composed of the first resistor R21, the first switching transistor Q21, the second switching transistor Q22, and the second resistor R22 charges the energy storage capacitor 122, and the voltage across the energy storage capacitor 122 will rise slowly, thereby providing an electrical signal with a voltage value that changes with time to the control end of the switching transistor 110. Among them, the constant current signal output by the constant current circuit 121 is a constant current, and the constant current is: I = U BE / R21, where U EB is equal to the voltage drop between the first end and the control end of the first switching transistor Q21, and R21 is the resistance value of the first resistor R21. Among them, the voltage value of the energy storage capacitor 122 is: U C = Q / C = (I×Δt) / C, where I is the value of the constant current signal, C is the capacitance value of the energy storage capacitor 122, and Δt is the charging duration. It can be known that there are two factors affecting the charging duration of the energy storage capacitor 122, namely the constant current I and the capacitance value of the energy storage capacitor 122. Among them, the constant current I can be adjusted by the resistance value R21 of the first resistor R21. The larger R21 is, the smaller the constant current I is, the longer the charging duration of the energy storage capacitor 122 is, the slower the switching transistor 110 turns on, and the smaller the pulsed current generated by the filter capacitor C61 in the filter circuit 160 is. The larger the capacitance value of the energy storage capacitor 122 is, the longer the charging duration is, the slower the switching transistor 110 turns on, and the smaller the pulsed current generated by the filter capacitor C61 is.

[0038] When the energy storage capacitor 122 is fully charged, the impedance across the energy storage capacitor 122 is almost infinite (i.e., the load of the constant current circuit 121 is infinite). At this time, the second switching transistor Q22 is in the saturation state, and the first switching transistor Q21 is in the amplification state. The voltage across the second resistor R22 is lower than the voltage value of the second power supply signal VCC2 by the voltage drops across the first terminal and the control terminal of the two first switching transistors Q21; the voltage across the energy storage capacitor 122 is close to the voltage value of the second power supply signal VCC2, that is, the voltage between the control terminal and the second communication terminal of the switching transistor 110 is stabilized at about the voltage difference between the second power supply signal VCC2 and the first power supply signal VCC1. The switching transistor 110 is fully turned on. When passing a large current, the voltage drop across the first communication terminal and the second communication terminal of the switching transistor 110 is almost 0, which can improve the utilization rate of the power supply.

[0039] The constant current circuit 121 of this embodiment includes a discrete circuit composed of a first resistor R21, a second resistor R22, a first switching transistor Q21, and a second switching transistor Q22. Its structure is simple and there are few components, which can reduce the cost of the constant current circuit 121, thereby reducing the cost of the soft start circuit 10.

[0040] In one embodiment, the first switching transistor Q21 and the second switching transistor Q22 can be bipolar transistors, which are not limited herein.

[0041] In one embodiment, continue to refer to Figure 2 , the signal generation circuit 120 further includes a first voltage regulator diode D21. The cathode of the first voltage regulator diode D21 is connected to one end of the energy storage capacitor 122, and the anode of the first voltage regulator diode D21 is grounded to GND. In this embodiment, the first voltage regulator diode D21 is provided. The first voltage regulator diode D21 can avoid the problem that the voltage of the second power supply signal VCC2 is too high, resulting in too large a voltage between the control terminal and the second communication terminal of the switching transistor 110 and damaging the switching transistor 110, and can enhance the stability of the soft start circuit 10.

[0042] In one embodiment, continue to refer to Figure 2, the soft start circuit 10 further includes a second voltage stabilizing diode D51 and a third resistor R51. The anode of the second voltage stabilizing diode D51 is connected to the second communication terminal of the switching transistor 110, and the cathode of the second voltage stabilizing diode D51 is connected to the control terminal of the switching transistor 110. Both ends of the third resistor R51 are respectively connected to the second communication terminal and the control terminal of the switching transistor 110. Among them, the second voltage stabilizing diode D51 can avoid the problem that the voltage of the second power supply signal VCC2 is too high, resulting in too large a voltage between the control terminal and the second communication terminal of the switching transistor 110 and damaging the switching transistor 110, and can enhance the stability of the soft start circuit 10. In addition, on the one hand, the third resistor R51 can prevent the problem that the charge on the switching transistor 110 has no discharge loop under electrostatic conditions, causing electrostatic breakdown of the switching transistor 110; on the other hand, it can prevent the problem that when the second power supply signal VCC2 is input next time, the switching transistor 110 immediately generates an uncontrollable large drain current, causing damage to the switching transistor 110.

[0043] In the soft start circuit 10 of this embodiment, the second voltage stabilizing diode D51 and the third resistor R51 are connected in parallel between the control terminal and the second communication terminal of the switching transistor 110, which can reduce the probability of damage to the switching transistor 110 and enhance the stability of the soft start circuit 10.

[0044] Refer to Figure 3 , Figure 3 FIG. is a schematic structural diagram of an embodiment of an electronic device provided by the present application. The electronic device 20 includes a soft start circuit 10, where the soft start circuit 10 is any one of the above-mentioned soft start circuit embodiments, and is not limited herein.

[0045] In one embodiment, the electronic device 20 may be a vehicle-mounted audio power amplifier or other high-power devices, which is not limited herein.

[0046] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A soft start circuit, characterized in that, Comprising: A switching tube, wherein a first communication terminal of the switching tube is used to access a first power supply signal, and a second communication terminal of the switching tube is used to connect to a load; A signal generation circuit, connected to a control terminal of the switching tube, and configured to access a second power supply signal, and based on the second power supply signal, provide an electrical signal with a voltage value varying over time to the control terminal of the switching tube to control the slow conduction of the switching tube; Wherein, a voltage value of the first power supply signal is less than a voltage value of the second power supply signal.

2. The soft start circuit according to claim 1, wherein The soft start circuit further includes a first power supply terminal and a second power supply terminal. The first power supply terminal is connected to the first communication terminal of the switching tube and accesses the first power supply signal. The second power supply terminal is connected to the signal generation circuit and accesses the second power supply signal.

3. The soft start circuit according to claim 1, wherein: The switching tube includes an N-type MOS tube.

4. The soft start circuit according to claim 1, characterized in that, The signal generation circuit includes: A constant current circuit, accessing the second power supply signal; A storage capacitor, one end of the storage capacitor is connected to the constant current circuit and the control terminal of the switching tube, and the other end of the storage capacitor is grounded; Wherein, the storage capacitor provides an electrical signal with a voltage value varying over time to the control terminal of the switching tube based on a constant current signal of the constant current circuit.

5. The slow start circuit according to claim 4, wherein The constant current circuit includes: A first resistor, one end of the first resistor is used to access the second power supply signal; A first switching tube, a first end of the first switching tube is connected to one end of the first resistor, and a control terminal of the first switching tube is connected to the other end of the first resistor; A second switching tube, a first end of the second switching tube is connected to the control terminal of the first switching tube and the other end of the first resistor, a second end of the second switching tube is connected to one end of the storage capacitor and the control terminal of the switching tube, and a control terminal of the second switching tube is connected to a second end of the first switching tube; A second resistor, one end of the second resistor is connected to the control terminal of the second switching tube and the second end of the first switching tube, and the other end of the second resistor is grounded.

6. The soft start circuit according to claim 4, wherein The signal generation circuit further includes: A first voltage stabilizing tube, a cathode of the first voltage stabilizing tube is connected to one end of the storage capacitor, and an anode of the first voltage stabilizing tube is grounded.

7. The soft start circuit according to claim 1, wherein The soft start circuit includes: A second voltage stabilizing tube, an anode of the second voltage stabilizing tube is connected to the second communication terminal of the switching tube, and a cathode of the second voltage stabilizing tube is connected to the control terminal of the switching tube; A third resistor, both ends of the third resistor are respectively connected to the second communication terminal and the control terminal of the switching tube.

8. The soft start circuit according to claim 1, characterized in that, The soft start circuit further includes: A filtering circuit, connected to the second communication terminal of the switching tube.

9. The slow start circuit according to claim 1, characterized in that The soft start circuit further includes: A bootstrap boost circuit, connected to the signal generation circuit, for providing the second power supply signal.

10. An electronic device, characterized in that, Comprising: The soft start circuit according to any one of claims 1 to 9.

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