A circuit structure for reducing output voltage variation

Abstract

The present invention provides a circuit structure for reducing output voltage variation, including a controller A1, a current sensing circuit, a stabilization circuit, and a charging circuit. In the current sensing circuit, a power supply voltage VDD is connected to ground in sequence through a current sensing transistor MS and a current sensing resistor RS. In the charging circuit, a power transistor MP outputs an output voltage VOUT and an output current IOUT for charging a battery load F1. The control terminal of the power transistor MP is connected to the control terminal of the current sensing transistor MS. The positive input terminal of the controller A1 is connected between a first feedback resistor RF1 and a second feedback resistor RF2, and the output terminal is connected to the control terminal of the power transistor MP for adjusting the conduction state of the power transistor MP and the current sensing transistor MS, thereby adjusting the output voltage VOUT. The stabilization circuit has a first terminal connected to the power supply voltage VDD, a second terminal connected to ground, a third terminal connected to the current output terminal of the current sensing transistor MS, and a fourth terminal connected to the current output terminal of the power transistor MP. The stabilization circuit controls the current flowing through the power transistor MP according to the magnitude of the output current IOUT, thereby reducing the rate of change of the output voltage VOUT.

Description

Technical Field

[0001] The present invention relates to the technical field of battery power supply, and in particular to a circuit structure for reducing output voltage variation. Background Art

[0002] Figure 1 The topology diagram of the battery charging circuit in the prior art is shown. Figure 1 The battery charging circuit includes a controller A1', a power tube MP', a first feedback resistor RF1', a second feedback resistor RF2' and a battery load F1'. The battery charging circuit outputs a voltage VOUT' and an output current IOUT', and charges the battery load F1' through the output voltage and output current.

[0003] In practical applications of battery charging circuits, the output voltage VOUT' often decreases as the output current IOUT' increases. This is because as the output current IOUT' increases, the current flowing through the power transistor MP' inevitably increases. If the output voltage VOUT' remains unchanged or increases, the gate-source and drain-source voltage differences of the power transistor MP' will remain unchanged or decrease, making it impossible to provide the required increased current. This conflicts with the actual increase in current flowing through the power transistor MP'. Therefore, to meet the circuit's current requirement, the output voltage VOUT' inevitably decreases as the output current IOUT' increases. This change in the output voltage VOUT' with the output current IOUT' is particularly pronounced when the output current IOUT' is low.

[0004] When the battery charging circuit is unloaded or the output current IOUT' is very low, the current in the power transistor MP' flows only through the first feedback resistor RF1' and the second feedback resistor RF2'. Since the resistance of the first and second feedback resistors RF1' and RF2' is typically very large, the current flowing through them is extremely small. Furthermore, due to the large size of the power transistor MP', it is almost in the off state at this time. Therefore, when the battery charging circuit is unloaded, that is, when the output current IOUT' is zero or very low, the control loop is in an unstable operating state. Only when the output current IOUT' is sufficiently high does the power transistor MP' turn on, and the control loop enters a stable state. Therefore, as the battery charging circuit gradually loads from unloaded state, that is, when the output current IOUT' increases from zero, the power transistor MP' gradually transitions from the off state to the on state, and the control loop transitions from an unstable operating state to a stable operating state. During this process, the output voltage VOUT' will change significantly. When the power tube MP' is turned on, the control loop is always in a stable working state. Then, when the output current IOUT' increases again, the change of the output voltage VOUT' will decrease.

[0005] Figure 2 The waveform of output voltage changing with output current is shown in Figure 2. Figure 2 , the output voltage VOUT' of the battery charging circuit is 3V when it is unloaded. When the output current IOUT' is 100mA, the output voltage VOUT' is 2.98V. Therefore, when the battery charging circuit changes from unloaded to fully loaded, that is, the output current IOUT' changes from 0mA to 100mA, the change rate of the output voltage VOUT' is . Summary of the Invention

[0006] The present invention aims to solve the problem that the output voltage of the existing battery charging circuit has a large rate of change during the process of gradually loading from no-load, thereby affecting the accuracy of the charging circuit.

[0007] According to a first aspect of the present invention, there is provided a circuit structure for reducing output voltage variation, comprising a controller A1, a current detection circuit, a stabilization circuit, and a charging circuit;

[0008] In the current detection circuit, the power supply voltage VDD is connected to the ground through the current detection tube MS and the current detection resistor RS in sequence;

[0009] In the charging circuit, the power supply voltage VDD is connected to ground in sequence through the power transistor MP, the first feedback resistor RF1, and the second feedback resistor RF2. The power supply voltage VDD is also connected to ground in sequence through the power transistor MP and the battery load F1. The current output terminal of the power transistor MP outputs an output voltage VOUT and an output current IOUT for charging the battery load F1.

[0010] The control end of the power tube MP is connected to the control end of the current sensing tube MS;

[0011] The controller A1 has a positive input terminal connected between the first feedback resistor RF1 and the second feedback resistor RF2, a negative input terminal connected to an external voltage VREF, and an output terminal connected to the control terminal of the power transistor MP, for adjusting the conduction state of the power transistor MP and the current sensing transistor MS, thereby adjusting the output voltage VOUT;

[0012] The first end of the stabilization circuit is connected to the power supply voltage VDD, the second end is grounded, the third end is connected to the current output end of the current detection tube MS, and the fourth end is connected to the current output end of the power tube MP. The stabilization circuit is configured to control the current flowing through the power tube MP according to the magnitude of the output current IOUT, so as to reduce the rate of change of the output voltage VOUT.

[0013] In one possible implementation, when the output current IOUT is less than a preset threshold, the stabilization circuit generates a pull-down auxiliary current at the current output end of the power tube MP, so that the auxiliary current flows through the power tube MP; when the output current IOUT exceeds the preset threshold, the stabilization circuit stops generating the auxiliary current, thereby reducing the rate of change of the output voltage VOUT.

[0014] In a possible implementation, the stabilization circuit includes a first switch tube M1, a second switch tube M2, a first stabilization resistor RC1, and a control module;

[0015] The current input terminal of the first switch tube M1 is connected to the current output terminal of the power tube MP, the current output terminal of the first switch tube M1 is grounded, and the control terminal is connected to the first node A of the control module;

[0016] The current input terminal of the second switch tube M2 is connected to the power supply voltage VDD, the current output terminal is connected to the first node A of the control module through the first stabilizing resistor RC1, and the control terminal is connected to the second node B of the control module;

[0017] The third node C of the control module is connected to the current output end of the current sensing tube MS.

[0018] In a possible implementation, the control module includes a third switch tube M3 and a fourth switch tube M4;

[0019] The current input terminal of the third switch tube M3 serves as the first node A, the current output terminal is grounded, and the control terminal is connected to the first node A;

[0020] The current input end of the fourth switch tube M4 serves as the second node B and the third node C, the current output end of the fourth switch tube M4 is grounded, and the control end of the fourth switch tube M4 is connected to the control end of the third switch tube M3.

[0021] In a possible implementation, the control module includes a fifth switch tube M5, a sixth switch tube M6, a seventh switch tube M7 and a trigger unit;

[0022] The current input terminal of the fifth switch tube M5 serves as the third node C, and the current output terminal of the fifth switch tube M5 is grounded;

[0023] The current input terminals of the sixth switch tube M6 and the seventh switch tube M7 are both connected to the trigger unit, and the current output terminals of the sixth switch tube M6 and the seventh switch tube M7 are both grounded;

[0024] The control terminals of the fifth switch tube M5, the sixth switch tube M6 and the seventh switch tube M7 all serve as the first node A;

[0025] The current input terminal of the seventh switch tube M7 is connected to the control terminal of the seventh switch tube M7.

[0026] In a possible implementation, the fifth switch tube M5 , the sixth switch tube M6 , the seventh switch tube M7 and the first switch tube M1 form a current mirror structure.

[0027] In a possible implementation, the control module further includes an eighth switch tube M8;

[0028] The current input terminal of the eighth switch tube M8 serves as the first node A, the current output terminal is grounded, and the control terminal serves as the third node C.

[0029] In a possible implementation, in the trigger unit, the power supply voltage VDD is grounded via the second stabilizing resistor RC2 and the ninth switch tube M9 in sequence;

[0030] The control end of the ninth switch tube M9 serves as the third node C.

[0031] In a possible implementation, the trigger unit further includes a tenth switch tube M10;

[0032] The current input terminal of the tenth switch tube M10 is connected to the power supply voltage VDD, the current output terminal is connected to the current input terminal of the sixth switch tube M6, and the control terminal is connected to the current input terminal of the ninth switch tube M9.

[0033] In one possible implementation, in the trigger unit, the power supply voltage VDD is connected to the current input terminal of the sixth switch tube M6 in sequence through the switch element and the eleventh switch tube M11; the power supply voltage VDD is further connected to the current input terminal of the seventh switch tube M7 in sequence through the third stabilizing resistor RC3 and the twelfth switch tube M12; and the power supply voltage VDD is further connected to ground in sequence through the thirteenth switch tube M13 and the fourth stabilizing resistor RC4.

[0034] The control end of the eleventh switch tube M11 is connected to the current output end of the eleventh switch tube M11;

[0035] The control ends of the twelfth switch tube M12 and the thirteenth switch tube M13 are both connected to the control end of the eleventh switch tube M11;

[0036] The current output end of the thirteenth switch tube M13 serves as the second node B.

[0037] In a possible implementation, the parameters of the eleventh switch tube M11 and the twelfth switch tube M12 are the same;

[0038] The eighth switch tube M8 and the ninth switch tube M9 have the same parameters.

[0039] In a possible implementation, the switching element is a diode or a diode-connected transistor.

[0040] According to the present invention, the current-sensing circuit detects current changes through a current-sensing transistor MS and a current-sensing resistor RS, providing real-time feedback signals to the stabilization circuit. Subsequently, by providing a stabilization circuit that works in conjunction with the charging circuit and the current-sensing circuit, a small current still flows through the power transistor MP when the charging circuit is unloaded or when the output current IOUT is very low. This ensures proper conduction of the power transistor MP under varying load conditions, preventing drastic fluctuations in the output voltage VOUT. Specifically, this prevents excessively high output voltage VOUT when the charging circuit is unloaded or when the output current is low. This structure effectively suppresses sudden changes in the output voltage VOUT during the transition from unloaded to loaded conditions in the battery charging circuit, improving the smoothness of the voltage output, reducing the rate of change of the output voltage, and enhancing the response stability and control accuracy of the entire system.

[0041] Furthermore, an auxiliary current path is introduced to provide auxiliary current to the power transistor MP when the output current is low, reducing the output voltage VOUT. The auxiliary path is automatically shut down when the output current exceeds a preset threshold, effectively reducing power consumption during normal operation. When the battery charging circuit switches from no-load to full-load, the rate of change of the output voltage VOUT is only half that of existing technologies, significantly improving voltage stability. Furthermore, by adjusting the auxiliary current, the no-load voltage and the rate of change of the output voltage can be flexibly set to suit different application requirements.

[0042] Furthermore, through the structural design of the control module in the circuit, the auxiliary current and the preset threshold are independent of the power supply voltage VDD and other variable parameters, so that a consistent control effect can be maintained under different power supply voltage VDD conditions. There is no need to adjust parameters for different power supply voltages, which simplifies the design process and enhances the adaptability and versatility of the circuit structure.

[0043] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The topological structure diagram of the battery charging circuit in the prior art is shown;

[0045] Figure 2shows the waveform of output voltage changing with output current;

[0046] Figure 3 A circuit topology diagram for reducing output voltage variation according to an embodiment of the present invention is shown;

[0047] Figure 4 A topological diagram of a circuit structure for reducing output voltage variation according to another embodiment of the present invention is shown;

[0048] Figure 5 A circuit structure topology diagram for reducing output voltage variation according to yet another embodiment of the present invention is shown;

[0049] Figure 6 A circuit topology diagram for reducing output voltage variation according to yet another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some, rather than all, structures related to the present application are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0051] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0052] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0053] Figure 3 FIG1 shows a circuit topology diagram for reducing output voltage variation according to an embodiment of the present invention. Figure 3As shown, the circuit structure for reducing output voltage variation includes a controller A1, a current sensing circuit 100, a stabilization circuit 200, and a charging circuit 300. In the current sensing circuit 100, the power supply voltage VDD is connected to ground sequentially through the current sensing transistor MS and the current sensing resistor RS. In the charging circuit 300, the power supply voltage VDD is connected to ground sequentially through the power transistor MP, the first feedback resistor RF1, and the second feedback resistor RF2. The power supply voltage VDD is also connected to ground sequentially through the power transistor MP and the battery load F1. The current output terminal of the power transistor MP outputs an output voltage VOUT and an output current IOUT for charging the battery load F1. The control terminal of the power transistor MP is connected to the control terminal of the current sensing transistor MS. The positive input terminal of the controller A1 is connected between the first feedback resistor RF1 and the second feedback resistor RF2, the negative input terminal is connected to the external voltage VREF, and the output terminal is connected to the control terminal of the power transistor MP. The controller A1 is used to adjust the conduction state of the power transistor MP and the current sensing transistor MS, thereby adjusting the output voltage VOUT. The stabilization circuit 200 has a first terminal connected to the power supply voltage VDD, a second terminal connected to ground, a third terminal connected to the current output terminal of the current-sense transistor MS, and a fourth terminal connected to the current output terminal of the power transistor MP. The stabilization circuit 200 is configured to control the current flowing through the power transistor MP based on the magnitude of the output current IOUT, thereby reducing the rate of change of the output voltage VOUT. Specifically, when the output current IOUT is less than a preset threshold, the stabilization circuit generates a pull-down auxiliary current at the current output terminal of the power transistor MP, causing a small current to flow through the power transistor MP. When the output current IOUT exceeds the preset threshold, the stabilization circuit stops generating the pull-down auxiliary current, thereby reducing the rate of change of the output voltage VOUT.

[0054] According to the above embodiment, the current-sensing circuit 100 detects current changes through the current-sensing transistor MS and the current-sensing resistor RS, providing a real-time feedback signal to the stabilization circuit 200. Subsequently, by providing the stabilization circuit 200 in conjunction with the charging circuit 300 and the current-sensing circuit 100, a small current still flows through the power transistor MP when the charging circuit 300 is unloaded or the output current IOUT is very low. This ensures proper conduction of the power transistor MP under various load conditions, preventing drastic fluctuations in the output voltage VOUT. Specifically, this prevents the output voltage VOUT from being excessively high when the charging circuit 300 is unloaded or has a low output current. This structure effectively suppresses sudden changes in the output voltage VOUT during the transition from unloaded to loaded state of the charging circuit 300, improves the smoothness of the voltage output, reduces the rate of change of the output voltage, and enhances the response stability and control accuracy of the entire system.

[0055] Figure 4 FIG. 1 shows a circuit topology diagram for reducing output voltage variation according to another embodiment of the present invention. Figure 4As shown, the stabilization circuit 200 in the circuit structure for reducing output voltage variation includes a first switch transistor M1, a second switch transistor M2, a first stabilization resistor RC1, and a control module 210. The current input terminal of the first switch transistor M1 is connected to the current output terminal of the power transistor MP. The current output terminal of the first switch transistor M1 is grounded, and the control terminal is connected to a first node A of the control module 210. The current input terminal of the second switch transistor M2 is connected to the power supply voltage VDD, the current output terminal is connected to the first node A of the control module 210 through the first stabilization resistor RC1, and the control terminal is connected to a second node B of the control module 210. A third node C of the control module is connected to the current output terminal of the current-sense transistor MS.

[0056] In this embodiment, when the output current IOUT is low, that is, when the charging circuit 300 is unloaded or the output current is low, the control module 210 sets the second node B to a low level, turning on the second switch M2. The voltage at the first node A is then pulled up through the second switch M2 and the first stabilizing resistor RC1, thereby increasing the voltage at the control terminal of the first switch M1 and turning on the first switch M1. At this point, the first switch M1 generates a pull-down current I1 at the current output terminal of the power transistor MP, ensuring that current always flows through the power transistor MP and preventing the output voltage VOUT from exceeding 100%. As the output current IOUT gradually increases and the system enters a normal load state, the current-sensing circuit 100 detects that the current flowing through the current-sensing resistor RS exceeds a preset threshold and pulls down or maintains the voltage at the first node A at a low level, turning off the first switch M1. At this point, the auxiliary current path is disconnected, and the power transistor MP continues to output current to the battery load F1. The current flowing through it is the output current IOUT, and the auxiliary path no longer participates in the power supply process.

[0057] According to this embodiment, the stabilization circuit 200 maintains a small auxiliary current flowing through the power transistor MP when the charging circuit 300 is in no-load state or the output current is small. Figure 2 It can be seen that when a small auxiliary current flows through power transistor MP, output voltage VOUT significantly decreases. In other words, the provision of stabilization circuit 200 effectively reduces the no-load voltage, thereby significantly reducing the rate of change of the output voltage when charging circuit 300 switches from a no-load state to a loaded state. Furthermore, the magnitude of this auxiliary current can be adjusted according to actual needs, thereby achieving precise control of the no-load voltage and the rate of change of the output voltage.

[0058] It should be noted that the control module 210 in the stabilization circuit 200 can be implemented in a variety of different structures to flexibly control the on and off of the first switch tube M1 under different design conditions.

[0059] Example 1

[0060] Figure 5 FIG. 1 shows a circuit topology diagram for reducing output voltage variation according to another embodiment of the present invention. Figure 5 As shown, the control module 210 in this circuit structure includes a third switch M3 and a fourth switch M4. The current input terminal of the third switch M3 serves as the first node A, the current output terminal is grounded, and the control terminal is connected to the first node A. The current input terminal of the fourth switch M4 serves as the second node B and the third node C, the current output terminal of the fourth switch M4 is grounded, and the control terminal of the fourth switch M4 is connected to the control terminal of the third switch M3.

[0061] In this embodiment 1, the working principle of the circuit for reducing output voltage variation is as follows: after the circuit is powered on, the initial output voltage VOUT is 0. At this time, the controller A1 outputs a low level to the control terminals of the power tube MP and the current sensing tube MS, turning them on. The output voltage VOUT begins to rise and eventually stabilizes at a preset no-load voltage value. , this voltage value is the design value of the no-load voltage. In some embodiments, the design value of the no-load voltage can be Figure 2 3V in.

[0062] At this time, since the charging circuit 300 is in a no-load state, the current in the power transistor MP only flows through the first feedback resistor RF1 and the second feedback resistor RF2. Since the resistance values ​​of the first feedback resistor RF1 and the second feedback resistor RF2 are usually very large, the current flowing through the power transistor MP is very small. In addition, since there is a positive correlation between the current flowing through the power transistor MP and the current IS flowing through the current-sensing transistor MS, the current IS flowing through the current-sensing transistor MS is also relatively small. In a specific design, the current IP flowing through the power transistor MP can be designed to be equal to Because current IS is small, the voltage across the current-sense resistor RS is also small, turning on the second switch M2. The control terminal voltages of the first, third, and fourth switches M1, M3, and M4 are pulled higher by the second switch M2 and the first stabilizing resistor RC1. Consequently, the first, third, and fourth switches M1, M3, and M4 are all turned on. At this point, current I1 (auxiliary current) flows through the first switch M1, current I3 flows through the third switch M3, and current I4 flows through the fourth switch M4. Therefore, when the charging circuit 300 is in the no-load state, current I1 flows through the power transistor MP.

[0063] In some embodiments, the current I1 is designed to be equal to , the current I4 is designed to be equal to .

[0064] At this time, the second switch tube M2 is in the on state and works in the linear region. The on resistance is very small and can be ignored in the calculation. Therefore, the current flowing through the third switch tube M3 is , where VTH3 is the conduction threshold voltage of the third switch tube M3. When the manufacturing process is known, the conduction threshold voltage is a fixed known value, RC1 is the resistance value of the first stabilizing resistor, and VDD is the power supply voltage. Thus, the current flowing through the first switch tube M1 can be obtained .

[0065] When the charging circuit 300 is in a loaded state, since the resistance values ​​of the first feedback resistor RF1 and the second feedback resistor RF2 are usually very large, the current flowing through the first feedback resistor RF1 and the second feedback resistor RF2 is very small and can be ignored in the calculation. Therefore, the current IP flowing through the power transistor MP is equal to IOUT+I1. , from which we can get the current flowing in the current detection tube MS , and because the current flowing through the fourth switch tube M4 , therefore, the current flowing into the current-sense resistor RS is , so the control terminal voltage of the second switch tube M2 is As the battery load increases, the output current IOUT increases, and the voltage at the control terminal of the second switch tube M2 increases. When the voltage at the control terminal of the second switch tube M2 rises to exceed the preset threshold, that is, When the second switch M2 is turned off, the first, third, and fourth switches M1, M3, and M4 are also turned off. The corresponding currents I1, I3, and I4 are all switched to zero, the auxiliary current path is closed, and the circuit enters a normal load output state. VTH2 is the turn-on threshold voltage of the second switch M2. If the manufacturing process is known, this turn-on threshold voltage is a fixed and known value.

[0066] Therefore, when current I1, current I3 and current I4 are at the switching point, , so the preset threshold value of the output current is .

[0067] From the above analysis, it can be seen that when the charging circuit 300 is in the no-load state, the current I1 always flows through the power tube MP. In some embodiments, the current I1 is designed to be 1mA, that is, , the no-load current at this time is 1mA, Figure 2 It can be seen that the no-load voltage at this time is 2.99V. When the output current exceeds the preset threshold, that is When the output current IOUT0 is set to 2mA, the current I1 is switched to 0, and only the output current IOUT flows through the power tube MP. At this time, IOUT0 is designed to meet the current value when the power tube MP is fully turned on, for example, 2mA. That is, when the output current IOUT exceeds 2mA, the current I1 and other currents will be switched to 0, and the power tube MP is fully turned on. This control strategy ensures that the power tube MP is fully turned on while avoiding the continuous supply of auxiliary current after the circuit enters stable load operation, thereby effectively reducing the overall power consumption of the system. When the output current IOUT reaches the full load current of 100mA, the current IOUT0 is set to 2mA. Figure 2 It can be seen that the corresponding output voltage VOUT is 2.98V. Therefore, when the charging circuit 300 changes from no-load to full-load, that is, the output current IOUT changes from 0mA to 100mA, the change rate of the output voltage VOUT is only From the above analysis, it can be seen that after adopting the circuit structure for reducing output voltage variation provided by the present invention, the rate of change of the output voltage VOUT during the process of switching from no-load to load can be reduced by half compared with the prior art, effectively improving the stability of the output voltage.

[0068] It should be noted that in actual use of the circuit, the parameter values ​​of current I1 and the preset threshold value IOUT0 can be flexibly set according to specific application requirements. For example, by adjusting the magnitude of current I1, the no-load voltage and the output voltage change rate can be effectively controlled, thereby further optimizing the stability of the system.

[0069] According to the above embodiment, an auxiliary current path is introduced to provide auxiliary current to the power transistor MP when the output current is low, thereby reducing the output voltage VOUT. Furthermore, the auxiliary path is automatically shut down when the output current exceeds a preset threshold, effectively reducing power consumption during normal operation. When the charging circuit 300 switches from no-load to full-load, the rate of change of the output voltage VOUT is only half that of the prior art, significantly improving voltage stability. Furthermore, by adjusting the magnitude of the auxiliary current, the no-load voltage and the rate of change of the output voltage can be flexibly set to suit different application requirements.

[0070] Example 2

[0071] The inventors discovered that in the circuit structure for reducing output voltage variation shown in Example 1, both current I1 and the preset threshold value IOUT0 are closely related to the power supply voltage VDD. When this circuit structure is applied to scenarios with different power supply voltages VDD, to meet the preset design requirements of I1 and IOUT0, the resistance values ​​of the current-sense resistor RS and the first stabilizing resistor RC1 need to be adjusted accordingly. However, if RS and RC1 are built-in resistors on the chip and their resistance values ​​are not adjustable, the structure will be difficult to adapt to different VDD voltage environments, limiting its application in multiple voltage platforms and resulting in poor adaptability. Therefore, to improve the adaptability of the circuit structure for reducing output voltage variation and expand its application range, the inventors proposed the circuit structure for reducing output voltage variation shown in Example 2 of the present invention. In addition, the circuit structure for reducing output voltage variation shown in Example 2 of the present invention also includes a first switch tube, a second switch tube, and a first stabilizing resistor. To distinguish it from Example 1, this Example 2 is represented by a first switch tube M1', a second switch tube M2', and a first stabilizing resistor RC1', where the current flowing through the first switch tube M1' is represented by I1'.

[0072] Figure 6 FIG. 1 shows a circuit topology diagram for reducing output voltage variation according to another embodiment of the present invention. Figure 6 As shown, the control module 210 in this circuit structure includes a fifth switch transistor M5, a sixth switch transistor M6, a seventh switch transistor M7, and a trigger unit 211. The current input terminal of the fifth switch transistor M5 serves as a third node C, and the current output terminal of the fifth switch transistor M5 is grounded. The current input terminals of the sixth switch transistor M6 and the seventh switch transistor M7 are both connected to the trigger unit 211, and the current output terminals of the sixth switch transistor M6 and the seventh switch transistor M7 are both grounded. The control terminals of the fifth switch transistor M5, the sixth switch transistor M6, and the seventh switch transistor M7 serve as a first node A and are all connected to the control terminal of the first switch transistor M1'. The current input terminal of the seventh switch transistor M7 is connected to the control terminal of the seventh switch transistor M7.

[0073] The fifth switch tube M5, the sixth switch tube M6, the seventh switch tube M7 and the first switch tube M1' form Current mirror structure.

[0074] The control module 210 further includes an eighth switch tube M8 , wherein a current input terminal of the eighth switch tube M8 serves as a first node A, a current output terminal is grounded, and a control terminal serves as a third node C.

[0075] In the trigger unit 211 , the power supply voltage VDD is grounded via the second stabilizing resistor RC2 and the ninth switch tube M9 in sequence, and the control end of the ninth switch tube M9 serves as the third node C.

[0076] The trigger unit 211 further includes a tenth switch tube M10 , whose current input terminal is connected to the power supply voltage VDD, whose current output terminal is connected to the current input terminal of the sixth switch tube M6 , and whose control terminal is connected to the current input terminal of the ninth switch tube M9 .

[0077] In the trigger unit 211, the power supply voltage VDD is connected to the current input terminal of the sixth switch M6 via the switch element and the eleventh switch M11. The power supply voltage VDD is also connected to the current input terminal of the seventh switch M7 via the third stabilizing resistor RC3 and the twelfth switch M12. The power supply voltage VDD is also connected to ground via the thirteenth switch M13 and the fourth stabilizing resistor RC4. The control terminal of the eleventh switch M11 is connected to the current output terminal of the eleventh switch M11. The control terminals of the twelfth and thirteenth switches M12 and M13 are both connected to the control terminal of the eleventh switch M11. The current output terminal of the thirteenth switch M13 serves as the second node B.

[0078] The switching element is a first diode D1 or a diode-connected transistor.

[0079] The parameters of the eleventh switch tube M11 and the twelfth switch tube M12 are the same, and the parameters of the eighth switch tube M8 and the ninth switch tube M9 are the same.

[0080] In the second embodiment, the working principle of the circuit for reducing the output voltage variation is as follows: after the circuit is powered on, the design value of the no-load voltage is In some embodiments, the design value of the no-load voltage can be Figure 2 3V in.

[0081] When the charging circuit 300 is unloaded, according to the analysis of the above embodiment 1, the current flowing through the power transistor MP and the current sensing transistor MS is very small, and the current IP flowing through the power transistor MP is designed to be equal to . Therefore, the terminal voltage of the current-sense resistor RS is small, that is, the control terminal voltages of the eighth switch tube M8 and the ninth switch tube M9 are also small, and the eighth switch tube M8 and the ninth switch tube M9 are both in the off state. The second stabilizing resistor RC2 pulls up the control terminal voltage of the tenth switch tube M10, so that the tenth switch tube M10 is also in the off state. At the same time, the control terminal voltage of the second switch tube M2' is pulled down by the fourth stabilizing resistor RC4, and the second switch tube M2' is turned on. At this time, the voltage of the first node A is pulled up by the second switch tube M2' and the first stabilizing resistor RC1', that is, the control terminal voltages of the first switch tube M1', the fifth switch tube M5, the sixth switch tube M6 and the seventh switch tube M7 are pulled up, and the first switch tube M1', the fifth switch tube M5, the sixth switch tube M6 and the seventh switch tube M7 are turned on. After the sixth switch M6 is turned on, the control terminal voltages of the eleventh, twelfth, and thirteenth switches M11, M12, and M13 are pulled down by the sixth switch M6, and the eleventh, twelfth, and thirteenth switches M11, M12, and M13 are also turned on. At this point, the turned-on twelfth switch M12 continuously pulls up the control terminal voltages of the first, fifth, sixth, and seventh switches M1', M5, M6, and M7. Currents I1', I5, I6, and I7 flow through the first, fifth, sixth, and seventh switches M1', M5, M6, and M7, respectively. Simultaneously, the turn-on of the thirteenth switch M13 raises the control terminal voltage of the second switch M2', causing the second switch M2' to turn off.

[0082] At this time, the fifth switch tube M5, the sixth switch tube M6, the seventh switch tube M7 and the first switch tube M1' form The current mirror structure, the ratio of current I5, current I6, current I7 and current I1' is: , that is, the current I6 is equal to the current I7. Furthermore, because the eleventh switch tube M11 and the twelfth switch tube M12 have the same parameters, the gate-source voltage difference between the eleventh switch tube M11 and the twelfth switch tube M12 is equal. Therefore, the voltage difference across the third stabilizing resistor RC3 is equal to the forward conduction voltage drop VD1 of the first diode D1. When the manufacturing process is known, the forward conduction voltage drop VD1 is a fixed and known value. Therefore, we can obtain: .

[0083] When the charging circuit 300 is in a loaded state, according to the analysis of the first embodiment, the current IP flowing through the power transistor MP is equal to IOUT+I1′, and the current flowing through the current sensing transistor MS is equal to , and because the current flowing through the fifth switch tube M5 , therefore, the current flowing into the current-sense resistor RS is , so the control terminal voltage of the ninth switch tube M9 is As the load increases, the output current IOUT gradually increases, and the control terminal voltages of the eighth and ninth switches M8 and M9 also increase accordingly. When the control terminal voltages of the eighth and ninth switches M8 and M9 exceed their turn-on threshold voltage VTH (the eighth and ninth switches M8 and M9 have identical parameters, and given a known manufacturing process, VTH is a fixed, known value), the eighth and ninth switches M8 and M9 turn on. After the eighth switch M8 turns on, it pulls down the control terminal voltages of the fifth, sixth, and seventh switches M5, M6, M7, and first switches M1', turning off the fifth, sixth, and seventh switches M7 and M1'. At the same time, after the ninth switch is turned on, it lowers the voltage at the control terminal of the tenth switch M10, turning the tenth switch M10 on. This in turn raises the voltage at the control terminals of the eleventh, twelfth, and thirteenth switches M11, M12, and M13. Consequently, the eleventh, twelfth, and thirteenth switches M11, M12, and M13 are turned off. At this point, currents I5, I6, I7, and I1' are switched to zero.

[0084] Therefore, when the currents I5, I6, I7, and I1' are at the switching point, , so the preset threshold value of the output current is .

[0085] From the above analysis, it can be seen that when the charging circuit 300 is in the no-load state, the current I1' always flows through the power tube MP. In some embodiments, the current I1' is designed to be 1mA, that is, , the no-load current at this time is 1mA, Figure 2 It can be seen that the no-load voltage at this time is 2.99V. When the output current exceeds the preset threshold, that is When the output current IOUT0 exceeds 2 mA, the current I1' switches to 0, and only the output current IOUT flows through the power transistor MP. At this time, the preset threshold value IOUT0 is designed to meet the current value when the power transistor MP is fully turned on, for example, 2 mA. That is, when the output current IOUT exceeds 2 mA, the current I1' and other currents will switch to 0, and the power transistor MP will be fully turned on. At the same time, although after the thirteenth switch M13 is turned off, the control terminal voltage of the second switch transistor M2' is pulled down by the fourth stabilizing resistor RC4, causing the second switch transistor M2' to turn on, thereby forming a current path in the branch formed by the second switch transistor M2', the eighth switch transistor M8, and the first stabilizing resistor RC1', because the first stabilizing resistor RC1' is a high-resistance resistor, the current in this branch is extremely small and can be almost ignored. Therefore, the circuit structure for reducing output voltage variation proposed in this embodiment 2 effectively reduces power consumption during stable circuit operation while ensuring that the power transistor MP is fully turned on.

[0086] When the output current IOUT reaches the full load current of 100mA, Figure 2 It can be seen that the corresponding output voltage VOUT is 2.98V. Therefore, when the charging circuit 300 changes from no-load to full-load, that is, the output current IOUT changes from 0mA to 100mA, the change rate of the output voltage VOUT is only From the above analysis, it can be seen that after adopting the circuit structure for reducing output voltage variation provided by the present invention, the variation rate of the output voltage VOUT during the process of switching from no-load to load can be reduced by half, effectively improving the stability of the output voltage.

[0087] During actual use of the circuit, the parameter values ​​of the current I1 ′ and the preset threshold value IOUT0 can be flexibly set according to specific application requirements.

[0088] According to the above embodiment, an auxiliary current path is introduced to allow a fixed low current I1' (auxiliary current) to flow through the power transistor MP when no-load, thereby reducing the output voltage VOUT. As the charging circuit 300 transitions from no-load to full-load, the output voltage VOUT only drops by approximately 0.01V, a rate of change that is half that of the prior art, significantly improving output voltage stability. When the output current exceeds the preset threshold IOUT0, the auxiliary current path automatically shuts down, ensuring the normal operation of the power transistor MP while significantly reducing power consumption during stable circuit operation. Furthermore, in the circuit structure for reducing output voltage variation proposed in this second embodiment, both the current I1' and the preset threshold IOUT0 are independent of the power supply voltage VDD and other variable parameters. Therefore, this circuit structure is applicable to circuits with any power supply voltage VDD. As long as the current I1' and the preset threshold IOUT0 remain the same as the designed values, stable operation is achieved without adjusting other parameters, simplifying the circuit adaptation process, improving versatility, and broadening its application scope.

[0089] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A circuit structure for reducing output voltage variation, characterized in that: It includes controller A1, current detection circuit, stabilization circuit and charging circuit; In the current detection circuit, the power supply voltage VDD is connected to the ground through the current detection tube MS and the current detection resistor RS in sequence; In the charging circuit, the power supply voltage VDD is connected to ground in sequence through the power transistor MP, the first feedback resistor RF1, and the second feedback resistor RF2. The power supply voltage VDD is also connected to ground in sequence through the power transistor MP and the battery load F1. The current output terminal of the power transistor MP outputs an output voltage VOUT and an output current IOUT for charging the battery load F1. The control end of the power tube MP is connected to the control end of the current sensing tube MS; The controller A1 has a positive input terminal connected between the first feedback resistor RF1 and the second feedback resistor RF2, a negative input terminal connected to an external voltage VREF, and an output terminal connected to the control terminal of the power transistor MP, for adjusting the conduction state of the power transistor MP and the current sensing transistor MS, thereby adjusting the output voltage VOUT; The first end of the stabilization circuit is connected to the power supply voltage VDD, the second end is grounded, the third end is connected to the current output end of the current detection tube MS, and the fourth end is connected to the current output end of the power tube MP. The stabilization circuit is configured to control the current flowing through the power tube MP according to the magnitude of the output current IOUT, so as to reduce the rate of change of the output voltage VOUT.

2. The circuit structure according to claim 1, wherein: When the output current IOUT is less than a preset threshold, the stabilization circuit generates a pull-down auxiliary current at the current output end of the power tube MP, so that the auxiliary current flows through the power tube MP; when the output current IOUT exceeds the preset threshold, the stabilization circuit stops generating the auxiliary current, thereby reducing the rate of change of the output voltage VOUT.

3. The circuit structure according to claim 2, wherein: The stabilization circuit includes a first switch tube M1, a second switch tube M2, a first stabilization resistor RC1 and a control module; The current input terminal of the first switch tube M1 is connected to the current output terminal of the power tube MP, the current output terminal of the first switch tube M1 is grounded, and the control terminal is connected to the first node A of the control module; The current input terminal of the second switch tube M2 is connected to the power supply voltage VDD, the current output terminal is connected to the first node A of the control module through the first stabilizing resistor RC1, and the control terminal is connected to the second node B of the control module; The third node C of the control module is connected to the current output end of the current sensing tube MS.

4. The circuit structure according to claim 3, wherein: The control module includes a third switch tube M3 and a fourth switch tube M4; The current input terminal of the third switch tube M3 serves as the first node A, the current output terminal is grounded, and the control terminal is connected to the first node A; The current input end of the fourth switch tube M4 serves as the second node B and the third node C, the current output end of the fourth switch tube M4 is grounded, and the control end of the fourth switch tube M4 is connected to the control end of the third switch tube M3.

5. The circuit structure according to claim 3, wherein: The control module includes a fifth switch tube M5, a sixth switch tube M6, a seventh switch tube M7 and a trigger unit; The current input terminal of the fifth switch tube M5 serves as the third node C, and the current output terminal of the fifth switch tube M5 is grounded; The current input terminals of the sixth switch tube M6 and the seventh switch tube M7 are both connected to the trigger unit, and the current output terminals of the sixth switch tube M6 and the seventh switch tube M7 are both grounded; The control terminals of the fifth switch tube M5, the sixth switch tube M6 and the seventh switch tube M7 all serve as the first node A; The current input terminal of the seventh switch tube M7 is connected to the control terminal of the seventh switch tube M7.

6. The circuit structure according to claim 5, characterized in that: The fifth switch tube M5, the sixth switch tube M6, the seventh switch tube M7 and the first switch tube M1 form Current mirror structure.

7. The circuit structure according to claim 6, characterized in that: The control module further includes an eighth switch tube M8; The current input terminal of the eighth switch tube M8 serves as the first node A, the current output terminal is grounded, and the control terminal serves as the third node C.

8. The circuit structure according to claim 7, characterized in that: In the trigger unit, the power supply voltage VDD is grounded via the second stabilizing resistor RC2 and the ninth switch tube M9 in sequence; The control end of the ninth switch tube M9 serves as the third node C.

9. The circuit structure according to claim 8, characterized in that: The trigger unit further includes a tenth switch tube M10; The current input terminal of the tenth switch tube M10 is connected to the power supply voltage VDD, the current output terminal is connected to the current input terminal of the sixth switch tube M6, and the control terminal is connected to the current input terminal of the ninth switch tube M9.

10. The circuit structure according to claim 9, characterized in that: In the trigger unit, the power supply voltage VDD is connected to the current input terminal of the sixth switch tube M6 in sequence through the switch element and the eleventh switch tube M11. The power supply voltage VDD is also connected to the current input terminal of the seventh switch tube M7 in sequence through the third stabilizing resistor RC3 and the twelfth switch tube M12. The power supply voltage VDD is also connected to ground in sequence through the thirteenth switch tube M13 and the fourth stabilizing resistor RC4. The control end of the eleventh switch tube M11 is connected to the current output end of the eleventh switch tube M11; The control ends of the twelfth switch tube M12 and the thirteenth switch tube M13 are both connected to the control end of the eleventh switch tube M11; The current output end of the thirteenth switch tube M13 serves as the second node B.

11. The circuit structure according to claim 10, characterized in that: The parameters of the eleventh switch tube M11 and the twelfth switch tube M12 are the same; The eighth switch tube M8 and the ninth switch tube M9 have the same parameters.

12. The circuit structure according to claim 10, wherein: The switching element is a diode or a diode-connected transistor.

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