Power switching circuit and power supply device

Abstract

The utility model discloses an embodiment of power supply switch circuit and power supply device, this power supply switch circuit includes switch module, switch control module, voltage control module and protection module, and the input end of switch module is connected input power supply, and the output end of switch module is connected load, the output end of switch control module is connected with the first end of protection module, and the second end of protection module is connected with the control end of switch module, and the third end of protection module is connected with input power supply, and switch control module is used for controlling the on -off of switch module, the first end of voltage control module is connected with the output end of switch control module, and the second end of voltage control module is connected with the control end of switch module, and voltage control module is used for controlling the voltage of control end of switch module when switch module is off. The technical scheme provided by the utility model embodiment can eliminate the problem that switch module appears again self conduction after being off, and improve the off reliability.

Description

Technical Field

[0001] This utility model relates to the field of switching power supply technology, and in particular to a power switching circuit and power supply device. Background Technology

[0002] In the design process of power-off using switching devices, the switching devices may self-conduct after power-off, causing them to malfunction or even become damaged.

[0003] Therefore, there is an urgent need for a power switch circuit to prevent the switching devices from self-conducting during the shutdown process. Utility Model Content

[0004] This utility model provides a power switch circuit and power supply device to eliminate the self-conduction phenomenon of the switching device during the shutdown process.

[0005] According to one aspect of the present invention, a power switch circuit is provided, comprising:

[0006] A switching module, wherein the input terminal of the switching module is connected to an input power supply, and the output terminal of the switching module is connected to a load;

[0007] The system includes a switch control module and a protection module. The output terminal of the switch control module is connected to the first terminal of the protection module, the second terminal of the protection module is connected to the control terminal of the switch module, and the third terminal of the protection module is connected to the input power supply. The switch control module is used to control the on / off state of the switch module.

[0008] A voltage control module is provided, wherein a first terminal of the voltage control module is connected to the output terminal of the switch control module, and a second terminal of the voltage control module is connected to the control terminal of the switch module. The voltage control module is used to control the voltage at the control terminal of the switch module when the switch module is turned off.

[0009] Optionally, the switching module includes a dual-channel transistor;

[0010] The first gate and the second gate of the dual-channel transistor are both connected to the second terminal of the protection module, the first source and the second source of the dual-channel transistor are both connected to the input power supply, and the first drain, the second drain, the third drain and the fourth drain of the dual-channel transistor are all connected to the load.

[0011] Optionally, the dual-channel transistor is a dual P-channel field-effect transistor.

[0012] Optionally, the voltage control module includes a diode, with the first terminal of the diode connected to the output terminal of the switch control module and the second terminal of the diode connected to the control terminal of the switch module.

[0013] Optionally, the protection module includes a first resistor, a second resistor, and a first capacitor;

[0014] The first end of the first resistor is connected to the input power supply, the second end of the first resistor is connected to the output terminal of the switch control module, the first end of the second resistor is connected to the second end of the first resistor, the second end of the second resistor is connected to the control terminal of the switch module, the first end of the first capacitor is connected to the input power supply, and the second end of the first capacitor is connected to the control terminal of the switch module.

[0015] The voltage control module is connected in parallel with the second resistor.

[0016] Optionally, the resistance of the second resistor is greater than the resistance of the first resistor.

[0017] Optionally, it further includes a signal control module, which is connected to the control terminal of the switch control module and is used to control the on / off state of the switch control module.

[0018] Optionally, the switch control module includes a transistor, a third resistor, a fourth resistor, a fifth resistor, and a second capacitor;

[0019] The first end of the third resistor is connected to the signal control module, the second end of the third resistor is connected to the control electrode of the transistor, the first electrode of the transistor is connected to the first end of the protection module via the fourth resistor, the second electrode of the transistor is grounded, the first end of the fifth resistor is connected to the control electrode of the transistor, the second end of the fifth resistor is grounded, the first end of the second capacitor is connected to the control electrode of the transistor, and the second end of the second capacitor is grounded.

[0020] Optionally, it may also include a power module connected to the input terminal of the switch module, the power module being used to provide the input power.

[0021] According to another aspect of the present invention, a power supply device is provided, including the power switch circuit provided in any embodiment of the present invention.

[0022] The power switch circuit and power supply device provided in this embodiment of the utility model, by setting a voltage control module, can quickly charge the Miller capacitor inside the switch module by the voltage output of the switch control module when the switch module is turned off, so that the voltage at the control terminal of the switch module can quickly reach the turn-off voltage, thereby eliminating the problem of the switch module re-conducting after being turned off and improving the turn-off reliability.

[0023] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of a power switch circuit provided in an embodiment of this utility model;

[0026] Figure 2 This is a schematic diagram of another power switch circuit provided in an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the structure of a dual P-channel field-effect transistor provided in this embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of another power switch circuit provided in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of another power switch circuit provided in an embodiment of the present invention;

[0030] Figure 6 A schematic diagram of the current waveform of a switching module provided in an embodiment of this utility model. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0033] Figure 1 This is a schematic diagram of a power switch circuit provided in an embodiment of the present invention, with reference to... Figure 1 The power switch circuit provided in this embodiment includes:

[0034] Switch module 10, the input terminal of switch module 10 is connected to the input power supply VDD, and the output terminal of switch module 10 is connected to the load 50;

[0035] The switch control module 20 and the protection module 30 are provided. The output terminal of the switch control module 20 is connected to the first terminal of the protection module 30, the second terminal of the protection module 30 is connected to the control terminal of the switch module 10, and the third terminal of the protection module 30 is connected to the input power supply VDD. The switch control module 20 is used to control the on and off of the switch module 10.

[0036] The voltage control module 40 has its first terminal connected to the output terminal of the switch control module 20 and its second terminal connected to the control terminal of the switch module 10. The voltage control module 40 is used to control the voltage at the control terminal of the switch module 10 when the switch module 10 is turned off.

[0037] Specifically, the switch module 10 is connected to the load 50 and is used to control the power-on or power-off of the load 50. Taking the load 50 as an example, which can be an LCD display or an LED display, when the switch module 10 is turned on, the load 50 is powered on and turned on; when the switch module 10 is turned off, the load is powered off and turned off. The power supply can be provided by the input power supply VDD.

[0038] The switch control module 20 is used to control the switching module 10 to turn on or off. Indirectly controlling the switching module 10 through the switch control module 20 prevents voltage or current backflow from affecting the state of the switching module 10, thus improving the reliability of the switching module 10's on / off state. The protection module 30 acts as a buffer to prevent voltage surges to the control terminal of the switching module 10.

[0039] Here, the switching module 10 typically includes a transistor, which contains a Miller capacitance (the capacitance between the gate and drain of the transistor). Taking the switching module 10 responding to a high-level turn-off as an example, when the switching control module 20 controls the switching module 10 to turn off, the drain voltage of the transistor will change and be coupled to the gate through the Miller capacitance, causing the gate voltage of the transistor to not rise rapidly and to be pulled down. When the gate voltage is pulled down to less than the threshold voltage, the transistor will turn on again, resulting in a phenomenon where it cannot be turned off.

[0040] In this embodiment, by setting a voltage control module 40, when the switch module 10 is turned off, the voltage output by the switch control module 20 can quickly charge the Miller capacitor inside the switch module 10 through the voltage control module 40, so that the voltage at the control terminal of the switch module 10 can quickly reach the turn-off voltage, thereby eliminating the problem of the switch module 10 re-conducting after being turned off and improving the turn-off reliability.

[0041] Figure 2 This is a schematic diagram of another power switch circuit provided in an embodiment of the present invention, with reference to... Figure 2 Based on the above embodiments, optionally, the switching module 10 includes a dual-channel transistor U1, the first gate G1 (pin 2) and the second gate G2 (pin 4) of the dual-channel transistor U1 are both connected to the second terminal of the protection module 30, the first source S1 (pin 1) and the second source S2 (pin 3) of the dual-channel transistor U1 are both connected to the input power supply VDD, and the first drain D1 (pin 7), the second drain D11 (pin 8), the third drain D2 (pin 5) and the fourth drain D22 (pin 6) of the dual-channel transistor U1 are all connected to the load 50.

[0042] Specifically, the dual-channel transistor U1 is a dual P-channel field-effect transistor. Figure 3 This is a schematic diagram of the structure of a dual P-channel field-effect transistor provided in an embodiment of the present invention, combined with... Figure 3 The dual P-channel MOSFET uses two independent P-channel MOSFETs, which are fabricated on the same chip. This allows for convenient control of two independent power supplies and provides strong driving capability and current density, thereby improving the reliability and stability of load control.

[0043] Figure 4This is a schematic diagram of another power switch circuit provided in an embodiment of the present invention, with reference to... Figure 4 Based on the above embodiments, optionally, the voltage control module 40 includes a diode DIO, the first terminal of the diode DIO is connected to the output terminal of the switch control module 20, and the second terminal of the diode DIO is connected to the control terminal of the switch module 10.

[0044] In this design, the first terminal of diode DIO can be positive, and the second terminal can be negative. The first terminal of diode DIO is connected to the output terminal of the switch control module 20, and the second terminal of diode DIO is connected to the first gate G1 and the second gate G2 of the dual-channel field-effect transistor U1. During the turn-off process of the dual-channel field-effect transistor U1 (a dual P-channel field-effect transistor), the voltage at the output terminal of the switch control module 20 is at a high potential, and diode DIO is unidirectionally conducting. This provides a fast charging path for the Miller capacitance of the dual-channel field-effect transistor U1, rapidly charging the Miller capacitance and thus accelerating the rise of the voltages at the first gate G1 and the second gate G2. This completely turns off the dual-channel field-effect transistor U1, preventing it from self-conducting. Furthermore, during the conduction phase of the dual-channel field-effect transistor U1, diode D1 can be reverse-biased to cut off, without affecting the discharge process of the first gate G1 and the second gate G2, ensuring that the dual-channel field-effect transistor U1 can conduct normally.

[0045] Figure 5 This is a schematic diagram of another power switch circuit provided in an embodiment of the present invention, with reference to... Figure 5 Based on the above embodiments, optionally, the protection module 30 includes a first resistor R1, a second resistor R2, and a first capacitor C1; the first end of the first resistor R1 is connected to the input power supply VDD, the second end of the first resistor R1 is connected to the output terminal of the switch control module 20, the first end of the second resistor R2 is connected to the second end of the first resistor R1, the second end of the second resistor R2 is connected to the control terminal of the switch module 10, the first end of the first capacitor C1 is connected to the input power supply VDD, and the second end of the first capacitor C1 is connected to the control terminal of the switch module 10. The first capacitor C1 plays a filtering role, used to filter out high-frequency noise in the input power supply VDD, making the input power supply VDD more stable.

[0046] The voltage control module 40 is connected in parallel with the second resistor R2, that is, the diode DIO is connected in parallel with the second resistor R2.

[0047] The resistance of the second resistor R2 is greater than that of the first resistor R1. The first resistor R1 and the second resistor R2 are used for voltage division and current limiting to ensure that the first gate G1 and the second gate G2 of the dual-channel field-effect transistor U1 operate under appropriate voltage and current conditions.

[0048] Optionally, it also includes a signal control module 60, which is connected to the control terminal of the switch control module 20 and is used to control the on / off state of the switch control module 20.

[0049] The switch control module 20 includes a transistor Q1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a second capacitor C2. The first terminal of the third resistor R3 is connected to the signal control module 60, and the second terminal of the third resistor R3 is connected to the control electrode of the transistor Q1. The first electrode of the transistor Q1 is connected to the first terminal of the protection module 30 via the fourth resistor R4, and the second electrode of the transistor Q1 is grounded. The first terminal of the fifth resistor R5 is connected to the control electrode of the transistor Q1, and the second terminal of the fifth resistor R5 is grounded. The first terminal of the second capacitor C2 is connected to the control electrode of the transistor Q1, and the second terminal of the second capacitor C2 is grounded. The third resistor R3, fourth resistor R4, and fifth resistor R5 function as voltage dividers and current limiters, while the second capacitor C2 functions as a filter. The transistor Q1 is an NPN transistor.

[0050] Specifically, when the signal control module 60 outputs a high level, transistor Q1 is turned on. The gate voltage of the dual-channel field-effect transistor U1 (the voltage between the first gate G1 and the second gate G2) discharges through transistor Q1, pulling the gate voltage of the dual-channel field-effect transistor U1 low. The gate-source voltage difference of the dual-channel field-effect transistor U1 is less than the threshold voltage of the dual-channel field-effect transistor U1, and the dual-channel field-effect transistor U1 is turned on. The input power supply VDD is transmitted to the load 50, enabling the load 50 to power on.

[0051] When the signal control module 60 outputs a low level, transistor Q1 is turned off, the discharge path of the gate voltage (the voltage between the first gate G1 and the second gate G2) of the dual-channel field-effect transistor U1 is cut off, the gate-source voltage difference of the dual-channel field-effect transistor U1 is 0V, which is greater than the threshold voltage of the dual-channel field-effect transistor U1, the dual-channel field-effect transistor U1 is turned off, so that the load 50 can be turned off.

[0052] Figure 6 This is a schematic diagram of the current waveform of a switching module provided in an embodiment of the present invention. The thin solid line represents the current waveform i in the prior art, and the thick solid line represents the current waveform i in this solution. (Refer to...) Figure 5 and Figure 6After transistor Q1 is turned off, the output voltage of the switch control module 20 is high. In the prior art, this high potential charges the Miller capacitance of the dual-channel field-effect transistor U1, preventing the gate voltage of the dual-channel field-effect transistor U1 from rising rapidly. During the charging process of the Miller capacitance, due to the long charging time, the decrease in the drain voltage of the dual-channel field-effect transistor U1 is coupled to the gate under the coupling effect of the Miller capacitance, thereby pulling down the gate voltage. When the gate voltage is pulled down to less than its own threshold voltage, the dual-channel field-effect transistor U1 turns on again (e.g., at time t), generating current i. When the Miller capacitance is fully charged, the gate voltage of the dual-channel field-effect transistor U1 rises, causing the dual-channel field-effect transistor U1 to turn off.

[0053] In this embodiment, after transistor Q1 is turned off, diode DIO conducts unidirectionally, adding a charging path. The high potential at the output of switch control module 20 will quickly charge the Miller capacitance of dual-channel field-effect transistor U1 through diode DIO, enabling the Miller capacitance to be quickly charged. This allows the gate voltage of dual-channel field-effect transistor U1 to rise rapidly, reducing the time it takes for the gate voltage to rise to the turn-off voltage and avoiding the phenomenon of self-conduction after turn-off. This improves the turn-off effect of dual-channel field-effect transistor U1 and enhances the control effect on load 50.

[0054] Optionally, in this embodiment, the power switch circuit further includes a power module (not shown in the figure), which is connected to the input terminal of the switch module 10 and is used to provide input power VDD.

[0055] Optionally, this utility model embodiment also provides a power supply device for supplying power to the load 50. The power supply device includes the power switch circuit provided in any of the above embodiments. Therefore, the power supply device also has the beneficial effects described in the above embodiments, and will not be repeated here.

[0056] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this utility model can be achieved, and this is not limited herein.

[0057] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A power switching circuit, characterized by, include: A switching module, wherein the input terminal of the switching module is connected to an input power supply, and the output terminal of the switching module is connected to a load; The system includes a switch control module and a protection module. The output terminal of the switch control module is connected to the first terminal of the protection module, the second terminal of the protection module is connected to the control terminal of the switch module, and the third terminal of the protection module is connected to the input power supply. The switch control module is used to control the on / off state of the switch module. A voltage control module is provided, wherein a first terminal of the voltage control module is connected to the output terminal of the switch control module, and a second terminal of the voltage control module is connected to the control terminal of the switch module. The voltage control module is used to control the voltage at the control terminal of the switch module when the switch module is turned off.

2. The power switch circuit according to claim 1, characterized in that, The switching module includes a dual-channel transistor; The first gate and the second gate of the dual-channel transistor are both connected to the second terminal of the protection module, the first source and the second source of the dual-channel transistor are both connected to the input power supply, and the first drain, the second drain, the third drain and the fourth drain of the dual-channel transistor are all connected to the load.

3. The power switch circuit according to claim 2, characterized in that, The dual-channel transistor is a dual P-channel field-effect transistor.

4. The power switch circuit according to claim 1, characterized in that, The voltage control module includes a diode, with the first terminal of the diode connected to the output terminal of the switch control module and the second terminal of the diode connected to the control terminal of the switch module.

5. The power switch circuit according to claim 1, characterized in that, The protection module includes a first resistor, a second resistor, and a first capacitor; The first end of the first resistor is connected to the input power supply, the second end of the first resistor is connected to the output terminal of the switch control module, the first end of the second resistor is connected to the second end of the first resistor, the second end of the second resistor is connected to the control terminal of the switch module, the first end of the first capacitor is connected to the input power supply, and the second end of the first capacitor is connected to the control terminal of the switch module. The voltage control module is connected in parallel with the second resistor.

6. The power switch circuit according to claim 5, characterized in that, The resistance of the second resistor is greater than the resistance of the first resistor.

7. The power switch circuit according to claim 1, characterized in that, It also includes a signal control module, which is connected to the control terminal of the switch control module and is used to control the on / off state of the switch control module.

8. The power switch circuit according to claim 7, characterized in that, The switch control module includes a transistor, a third resistor, a fourth resistor, a fifth resistor, and a second capacitor; The first end of the third resistor is connected to the signal control module, the second end of the third resistor is connected to the control electrode of the transistor, the first electrode of the transistor is connected to the first end of the protection module via the fourth resistor, the second electrode of the transistor is grounded, the first end of the fifth resistor is connected to the control electrode of the transistor, the second end of the fifth resistor is grounded, the first end of the second capacitor is connected to the control electrode of the transistor, and the second end of the second capacitor is grounded.

9. The power switch circuit according to claim 1, characterized in that, It also includes a power module, which is connected to the input terminal of the switch module and is used to provide the input power.

10. A power supply device, characterized in that, Includes the power switch circuit according to any one of claims 1-9.

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