Filter circuit with adjustable peak current during voltage sudden change
By introducing transistors and control units into the π-type filtering circuit, the charging branch current is automatically adjusted, which solves the problem of overcurrent of capacitor charging in traditional filtering circuits, and realizes the peak current adjustable when the voltage suddenly changes, ensuring the safety of the circuit.
Patent Information
- Application Number
- CN202422233854.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-09-11
AI Technical Summary
When the input signal voltage of the traditional π-type filter circuit suddenly changes, the capacitor charge generates a large current, resulting in overcurrent, and violating the limitations of the fuse circuit.
By introducing the first transistor and the second transistor into the π-type filtering circuit, the control signal is generated by using the control unit and the voltage divider unit to automatically turn off the first transistor to limit the charging branch current, and peak current regulation is achieved.
It effectively avoids overcurrent charging of capacitors when the input signal suddenly changes, ensuring safe operation of the circuit.
Smart Images
Figure CN223053004U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of filter circuits, and particularly relates to a filter circuit with adjustable peak current when the voltage suddenly changes. Background Art
[0002] Figure 1 In the traditional π-type filter circuit shown, the input signal is filtered and output from the output terminal VIN_1. When the voltage of the input signal suddenly changes, the six filter capacitors in the π-type filter circuit will have fluctuations in the charging capacity due to the increase or decrease of the voltage. When the input signal increases, a large current will be generated when the capacitor is charging, which is not allowed in some circuits equipped with fuses.
[0003] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the utility model, and should not be regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Utility Model
[0004] The purpose of the utility model is to provide a filter circuit with adjustable peak current when the voltage suddenly changes, which can avoid overcurrent during capacitor charging when the input signal suddenly changes.
[0005] In order to achieve the above purpose, the technical solution provided by a specific embodiment of the utility model is as follows:
[0006] A filter circuit with adjustable peak current when the voltage suddenly changes, including a π-type filter circuit, a first transistor, a second transistor, a control unit, and a voltage dividing unit. The π-type filter circuit includes a first capacitor, a second capacitor, and an inductor. The first end of the first capacitor and the first end of the inductor are connected to the input signal. The first end of the second capacitor is connected to the second end of the inductor. The second end of the first capacitor and the second end of the second capacitor are connected to the second end of the first transistor. The voltage dividing unit is connected to the input signal and the ground voltage to divide the input signal to generate a first control signal. The control end of the first transistor is connected to the voltage dividing unit to receive the first control signal. The first end of the first transistor is connected to the ground voltage through the control unit. The control unit is used to generate a second control signal based on the current on the first transistor. The first end of the second transistor is connected to the ground voltage. The second end of the second transistor is connected to the control end of the first transistor. The control end of the second transistor is connected to the control unit to receive the second control signal. The second transistor controls the on-off between the control end of the first transistor and the ground voltage based on the second control signal.
[0007] In one or more embodiments of the present utility model, the voltage dividing unit includes a first resistor and a second resistor. The first end of the first resistor is connected to an input signal, the second end of the first resistor is connected to the control end of a first transistor and the first end of the second resistor, and the second end of the second resistor is connected to a ground voltage.
[0008] In one or more embodiments of the present utility model, the control unit includes one or more third resistors connected in series or in parallel with each other. The first end of the third resistor is connected to a ground voltage, and the second end of the third resistor is connected to the first end of the first transistor and the control end of a second transistor.
[0009] In one or more embodiments of the present utility model, the filter circuit further includes a fourth resistor. The first end of the fourth resistor is connected to the control end of the second transistor, and the second end of the fourth resistor is connected to the control unit.
[0010] In one or more embodiments of the present utility model, the filter circuit further includes a filtering unit. The filtering unit is connected to the control end and the first end of the first transistor.
[0011] In one or more embodiments of the present utility model, the filtering unit includes a third capacitor. The first end of the third capacitor is connected to the control end of the first transistor, and the second end of the third capacitor is connected to the first end of the first transistor.
[0012] In one or more embodiments of the present utility model, the filtering unit further includes a fifth resistor. The first end of the fifth resistor is connected to the control end of the first transistor, and the second end of the fifth resistor is connected to the first end of the first transistor.
[0013] In one or more embodiments of the present utility model, the filter circuit further includes a voltage stabilizing unit. The voltage stabilizing unit is connected to the control end and the first end of the first transistor.
[0014] In one or more embodiments of the present utility model, the voltage stabilizing unit includes a diode. The first end of the diode is connected to the control end of the first transistor, and the second end of the diode is connected to the first end of the first transistor.
[0015] Compared with the prior art, the filter circuit with adjustable peak current during voltage mutation in the present utility model forms a charging branch by connecting a first capacitor and a second capacitor to a first transistor. When the current in the charging branch exceeds a certain threshold through the control unit and a second transistor, the first transistor is automatically turned off, thereby limiting the peak current for charging the first capacitor and the second capacitor. Description of the Drawings
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0017] Figure 1 It is the circuit schematic diagram of the π-type filter circuit in the prior art.
[0018] Figure 2 It is the circuit schematic diagram of the filter circuit in an embodiment of the present invention. Detailed implementation manners
[0019] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0020] "Coupled", "connected", or "linked" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrical conduction medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include a connection through other active or passive devices on the basis of achieving the same or similar functional purposes, such as a connection through a circuit or component such as a switch, a follower circuit, etc. In addition, in the invention, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity, or order between these technical features.
[0021] In the detailed description of the specification, reference is made to the drawings that form a part of it, where the same reference numerals always represent the same components, and which are shown by way of exemplary embodiments that can be implemented. It should be understood that other embodiments can be utilized without departing from the scope of the present disclosure, and structural or logical changes can be made. Therefore, the following detailed description should not be regarded as limiting.
[0022] The various operations in the specification may be described sequentially as a number of discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be order-dependent. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.
[0023] For the purposes of this disclosure, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of this disclosure, the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).
[0024] Various components and devices may be referred to or shown herein in the singular (e.g., "MOS transistor", "transistor", "switch", etc.), but this is merely for convenience of discussion, and any element referred to in the singular may include a plurality of such elements in accordance with the teachings herein.
[0025] The specification describes the use of the phrases "in one embodiment" or "in other embodiments" or "in some embodiments", which may each refer to one or more of the same or different embodiments. Additionally, the terms "comprising", "including", "having", etc. used with respect to the embodiments of the present disclosure are synonymous.
[0026] As Figure 2 shown, a filtering circuit with adjustable peak current during voltage mutation in one embodiment of the present utility model includes a π-type filtering circuit 10, a first transistor Q1, a second transistor Q2, a fourth resistor R25, a control unit 30, a voltage dividing unit 20, a filtering unit, and a voltage stabilizing unit.
[0027] The π-type filtering circuit 10 includes a first capacitor, a second capacitor, and an inductor L1. In one embodiment, there are 3 first capacitors, namely a first capacitor C3, a first capacitor C4, and a first capacitor C5, and there are 3 second capacitors, namely a second capacitor C6, a second capacitor C7, and a second capacitor C8. In other embodiments, other numbers of first capacitors and second capacitors may also be provided.
[0028] The first terminal of the first capacitor C3, the first terminal of the first capacitor C4, the first terminal of the first capacitor C5, and the first terminal of the inductor L1 are connected to the input signal VBAT1. The first terminal of the second capacitor C6, the first terminal of the second capacitor C7, and the first terminal of the second capacitor C8 are connected to the second terminal of the inductor L1 and form the signal output terminal VIN_1 of the filter circuit. The second terminals of the first capacitor C3, the first capacitor C4, the first capacitor C5, the second capacitor C6, the second capacitor C7, and the second capacitor C8 are connected to the second terminal of the first transistor Q1.
[0029] The voltage dividing unit 20 is connected to the input signal VBAT1 and the ground voltage GND to divide the input signal VBAT1 to generate a first control signal. The control terminal of the first transistor Q1 is connected to the voltage dividing unit 20 to receive the first control signal. The first terminal of the first transistor Q1 is connected to the ground voltage GND through the control unit 30, and the control unit 30 is used to generate a second control signal based on the current on the first transistor Q1. The first terminal of the second transistor Q2 is connected to the ground voltage GND. The second terminal of the second transistor Q2 is connected to the control terminal of the first transistor Q1. The control terminal of the second transistor Q2 is connected to the first terminal of the fourth resistor R25. The second terminal of the fourth resistor R25 is connected to the control unit 30 to receive the second control signal, and the second transistor Q2 controls the on-off between the control terminal of the first transistor Q1 and the ground voltage GND based on the second control signal.
[0030] The fourth resistor R25 is used to limit the control terminal current of the second transistor Q2. In other embodiments, the fourth resistor R25 may not be provided.
[0031] The filter unit is connected to the control terminal and the first terminal of the first transistor Q1. The voltage stabilizing unit is connected to the control terminal and the first terminal of the first transistor Q1.
[0032] As Figure 2 shown, the voltage dividing unit 20 includes a first resistor R15 and a second resistor R19. The first terminal of the first resistor R15 is connected to the input signal VBAT1. The second terminal of the first resistor R15 is connected to the control terminal of the first transistor Q1 and the first terminal of the second resistor R19 to generate a first control signal. The second terminal of the second resistor R19 is connected to the ground voltage GND.
[0033] As Figure 2 shown, the control unit 30 includes a plurality of third resistors connected in series or in parallel. The first terminal of the third resistor is connected to the ground voltage GND. The second terminal of the third resistor is connected to the first terminal of the first transistor Q1 and the control terminal of the second transistor Q2.
[0034] In one embodiment, there are 4 third resistors, namely third resistor R26, third resistor R27, third resistor R28, and third resistor R29. The first ends of third resistor R26 and third resistor R28 are connected to the ground voltage GND. The second ends of third resistor R26 and third resistor R28 are connected to the first ends of third resistor R27 and third resistor R29. The second ends of third resistor R27 and third resistor R29 are connected to the first end of the first transistor Q1 and the control end of the second transistor Q2. In other embodiments, the number and connection manner of the third resistors can be adjusted according to actual needs.
[0035] As Figure 2 shown, the filtering unit includes a third capacitor C15 and a fifth resistor R23. The first ends of the third capacitor C15 and the fifth resistor R23 are connected to the control end of the first transistor Q1. The second ends of the third capacitor C15 and the fifth resistor R23 are connected to the first end of the first transistor Q1.
[0036] As Figure 2 shown, the voltage stabilizing unit includes a diode ZD1. The first end (cathode) of the diode ZD1 is connected to the control end of the first transistor Q1. The second end (anode) of the diode ZD1 is connected to the first end of the first transistor Q1.
[0037] Preferably, the diode ZD1 is a Zener diode ZD1.
[0038] In one embodiment, the first transistor Q1 is an NMOS transistor. The first end of the first transistor Q1 is the source, the second end is the drain, and the control end is the gate. The second transistor Q2 is an NPN bipolar junction transistor. The first end of the second transistor Q2 is the emitter, the second end is the collector, and the control end is the base. In other embodiments, the first transistor Q1 can also be a PMOS transistor or other device, and the second transistor Q2 can also be a PNP bipolar junction transistor or other device. Then, the connection manner of the two transistors is adjusted adaptively.
[0039] In practical applications, when the input signal VBAT1 increases, the first control signal generated by voltage division of the voltage division unit 20 also increases. The first transistor Q1 is turned on, and a path is formed between the first capacitors C3, C4, C5 and the second capacitors C6, C7, C8 and the ground voltage GND. While the first and second capacitors are being charged, a charging current is generated. The current passes through the third resistors R26, R27, R28, and R29, and a second control signal value of I*R0 is generated at the second ends of the third resistors R27 and R29, where I is the charging current flowing through the first transistor Q1, and R0 is the series-parallel resistance value of the third resistors R26, R27, R28, and R29. In one embodiment, the resistance values of the third resistors R26, R27, R28, and R29 are all 0.2 Ω, so R0 = 0.2 Ω.
[0040] When the second control signal reaches 0.7 V, that is, when the charging current reaches 3.5 A, the second transistor Q2 is turned on, pulling down the control terminal voltage of the first transistor Q1. The first transistor Q1 is turned off, the current on the first transistor Q1 decreases, and the second control signal also decreases until it is lower than 0.7 V. The second transistor Q2 is turned off, and the first transistor Q1 is turned on again. In this way, the cycle is repeated to achieve the purpose of limiting the peak current for charging the first and second capacitors. In other embodiments, the resistance value of the third resistor can also be set according to actual requirements.
[0041] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.
[0042] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A filter circuit with adjustable peak current when voltage changes suddenly, characterized in that: The invention comprises a π-type filter circuit, a first transistor, a second transistor, a control unit and a voltage divider unit. The π-type filter circuit comprises a first capacitor, a second capacitor and an inductor. The first end of the first capacitor and the first end of the inductor are connected to the input signal, the first end of the second capacitor is connected to the second end of the inductor, the second end of the first capacitor and the second end of the second capacitor are connected to the second end of the first transistor, the voltage divider unit is connected to the input signal and the ground voltage to divide the input signal to generate a first control signal, the control end of the first transistor is connected to the voltage divider unit to receive the first control signal, the first end of the first transistor is connected to the ground voltage through the control unit, the control unit is used to generate a second control signal based on the current on the first transistor, the first end of the second transistor is connected to the ground voltage, the second end of the second transistor is connected to the control end of the first transistor, the control end of the second transistor is connected to the control unit to receive the second control signal, and the second transistor controls the on-off between the control end of the first transistor and the ground voltage based on the second control signal.
2. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 1 is characterized in that: The voltage dividing unit includes a first resistor and a second resistor, wherein a first end of the first resistor is connected to an input signal, a second end of the first resistor is connected to a control end of the first transistor and a first end of the second resistor, and a second end of the second resistor is connected to a ground voltage.
3. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 1, characterized in that: The control unit includes one or more third resistors connected in series or in parallel, a first end of the third resistor is connected to the ground voltage, and a second end of the third resistor is connected to the first end of the first transistor and the control end of the second transistor.
4. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 1, characterized in that: The filter circuit further includes a fourth resistor, a first end of the fourth resistor is connected to the control end of the second transistor, and a second end of the fourth resistor is connected to the control unit.
5. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 1, characterized in that: The filter circuit further includes a filter unit connected to the control end of the first transistor and the first end of the first transistor.
6. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 5, characterized in that: The filtering unit includes a third capacitor, a first end of the third capacitor is connected to the control end of the first transistor, and a second end of the third capacitor is connected to the first end of the first transistor.
7. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 6, characterized in that: The filtering unit further includes a fifth resistor, a first end of the fifth resistor is connected to the control end of the first transistor, and a second end of the fifth resistor is connected to the first end of the first transistor.
8. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 1, characterized in that: The filter circuit further includes a voltage stabilizing unit connected to the control end of the first transistor and the first end of the first transistor.
9. The filter circuit with adjustable peak current when voltage changes suddenly according to claim 8, characterized in that: The voltage stabilizing unit comprises a diode, a first end of the diode is connected to the control end of the first transistor, and a second end of the diode is connected to the first end of the first transistor.