Voltage dividing feedback circuit with trimming function, voltage regulating method thereof and switching power supply

Abstract

The application discloses a voltage dividing feedback circuit with trimming function, a voltage regulating method thereof and a switching power supply, which are used for regulating output voltage of a power circuit output end. The voltage dividing feedback circuit comprises an upper voltage dividing network and a lower voltage dividing network connected in series between the output end and a reference ground, and a dislocation trimming unit connected between a common node of the two and the reference ground. The dislocation trimming unit is connected in parallel with the lower voltage dividing network, and is provided with a feedback node for defining resistance voltage dividing ratio of the dislocation trimming unit and providing a feedback voltage. The voltage dividing feedback circuit sets an output voltage grade by regulating equivalent resistance of the upper voltage dividing network and / or the lower voltage dividing network, and trims the output voltage of the selected grade by regulating the resistance voltage dividing ratio, and equivalent resistance of the dislocation trimming unit remains constant in the trimming process. Thus, the functions of output voltage grade setting and precision calibration are decoupled, precise trimming is realized without affecting the output voltage grade, and circuit flexibility and control precision are improved.

Description

Technical Field

[0001] This application relates to the field of power management technology, specifically to a voltage divider feedback circuit with adjustment function, its voltage regulation method, and a switching power supply. Background Technology

[0002] In modern power management systems, precise output voltage control is crucial. To achieve stable output voltage regulation, a feedback control structure is typically employed. This involves connecting a voltage divider resistor network at the output terminal to sample the output voltage and generate a feedback voltage, which is then fed into an error amplifier. This feedback voltage is compared with an internal reference voltage, thereby adjusting the power stage's operating state and forming a closed-loop control. Traditional voltage divider feedback circuits generally consist of two fixed or adjustable resistors connected in series, with the feedback voltage taken from the connection point between them. Currently, there are two common methods for setting the output voltage: adjusting the reference voltage and adjusting the feedback voltage. The feedback voltage is often adjusted by changing the voltage division ratio of the resistors. When supporting multiple output voltage levels, a switch is often used to change the voltage division ratio by switching between different resistance values. However, manufacturing deviations, temperature drift, and layout mismatches in the resistors can cause a systematic offset in the feedback voltage, leading to a deviation of the output voltage from its nominal value. Existing technologies often compensate for this offset by fine-tuning a resistor in the main voltage divider network.

[0003] Figure 1 A schematic circuit diagram of a prior art voltage divider feedback circuit is shown. (e.g.) Figure 1 As shown, resistors R11, R12, and R13 are connected in series between the output terminal and the reference ground. The center tap of the adjustable resistor R12 provides the feedback voltage FB for the output voltage VO, which is input to the error amplifier to regulate the output voltage VO of the power circuit in a closed-loop manner. Typically, the output voltage level is adjusted by changing the voltage division ratio of either resistor R11 or R13, and then fine-tuned by adjusting the position of the center tap of resistor R12. For applications where the output voltage level is adjusted by changing the resistance of resistor R11, a switch is often used to adjust the resistance. The on-resistance of this switch is affected by factors such as power supply, which can impact accuracy. In high-voltage applications, it can also introduce new problems such as withstand voltage and parasitic effects. However, applications where the output voltage level is adjusted by changing the resistance of resistor R13 avoid these problems. Therefore, the output voltage level is usually adjusted by adjusting the resistance of the lower voltage divider resistor R13. However, in such applications, since the tap position on resistor R12 is the node for obtaining the feedback voltage FB, the accuracy deviation ratio is different under different output voltage levels, requiring multiple adjustments. This results in low precision in adjusting the output voltage and poor consistency in accuracy across multiple levels. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a voltage divider feedback circuit with adjustment function, its voltage regulation method, and a switching power supply.

[0005] According to one aspect of the present invention, a voltage divider feedback circuit with adjustment function is provided for adjusting the output voltage of the output terminal of a power circuit. The voltage divider feedback circuit includes: an upper voltage divider network connected between the output terminal and a voltage divider node; a lower voltage divider network connected between the voltage divider node and a reference ground; and an offset adjustment unit connected in parallel with the lower voltage divider network. A feedback node is provided to provide a feedback voltage, and the feedback node defines the resistive voltage division ratio of the offset adjustment unit. The voltage divider feedback circuit sets the output voltage level by adjusting the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network, and adjusts the output voltage of the selected level by adjusting the resistive voltage division ratio. During the adjustment process, the equivalent resistance of the offset adjustment unit remains constant.

[0006] Optionally, the upper voltage divider network, the lower voltage divider network, and the offset adjustment unit are all resistor networks, and the equivalent resistance of each resistor network remains constant during the adjustment process.

[0007] Optionally, when switching the output voltage level, the resistor voltage division ratio of the offset adjustment unit remains unchanged; and when adjusting the resistor voltage division ratio during the adjustment process, the output voltage level remains unchanged.

[0008] Optionally, the offset adjustment unit is divided by the feedback node into an upper equivalent resistance near the voltage divider node and a lower equivalent resistance near the reference ground. The voltage division ratio is the ratio of the upper equivalent resistance to the lower equivalent resistance. During the adjustment of the voltage division ratio, the resistance adjustment amounts of the upper equivalent resistance and the lower equivalent resistance are equal in magnitude and opposite in direction, so that the equivalent resistance of the offset adjustment unit remains constant.

[0009] Optionally, the feedback voltage and the set reference voltage are compared by an error amplifier to obtain an error amplification signal provided to the power circuit. The offset adjustment unit is used to compensate for the output voltage offset caused by the voltage deviation between the feedback voltage and the reference voltage. The voltage deviation includes the offset of the error amplifier and the offset of the reference voltage.

[0010] Optionally, after adjusting the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network to select the output voltage level, the ratio between the feedback voltage and the unadjusted output voltage is used as the voltage division coefficient, and the voltage divider feedback circuit is adjusted so that the ratio between the set reference voltage and the adjusted output voltage is used as the voltage division coefficient.

[0011] Optionally, the voltage deviation is proportional to the resistance adjustment of the upper equivalent resistor or the lower equivalent resistor, and the voltage divider feedback circuit adjusts the voltage division ratio of the resistor according to the proportional relationship. The proportional relationship is related to the reference voltage and the resistance value of the lower equivalent resistor before adjustment.

[0012] Optionally, each of the resistor networks consists of several resistors and several switches. The equivalent resistance of the upper voltage divider network or the lower voltage divider network and the voltage division ratio of the resistors are adjusted by controlling the on state of different switches. The switches include fuses, relays or transistors.

[0013] According to another aspect of the present invention, a switching power supply is provided, comprising: a power circuit for converting an input voltage into an output voltage; a voltage divider feedback circuit with adjustment function, connected between the output terminal of the power circuit and a reference ground, for generating a feedback voltage; and an error amplifier having a first input terminal receiving the feedback voltage, a second input terminal receiving a set reference voltage, and an output terminal connected to a control circuit of the power circuit to provide an error amplification signal, wherein the error amplifier adjusts the error amplification signal according to the difference between the feedback voltage and the reference voltage, and the control circuit adjusts the operating state of the power circuit according to the error amplification signal to stabilize the output voltage.

[0014] Optionally, the power circuit includes a switching transistor, an inductor, and an output capacitor, and the topology of the power circuit includes buck, boost, buck-boost, or flyback topologies.

[0015] According to another aspect of the present invention, a voltage regulation method is provided for a voltage divider feedback circuit with adjustment function, used to adjust the output voltage of the output terminal of a power circuit. The voltage divider feedback circuit includes an upper voltage divider network and a lower voltage divider network connected in series between the output terminal and a reference ground, and an offset adjustment unit connected in parallel with the lower voltage divider network. The offset adjustment unit has a feedback node that provides a feedback voltage, and the feedback node defines the resistive voltage division ratio of the offset adjustment unit. The voltage regulation method includes: adjusting the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network to set an output voltage level; passing the feedback voltage and a set reference voltage through an error amplifier to generate an error amplification signal provided to the power circuit to stabilize the output voltage; and adjusting the resistive voltage division ratio according to the voltage deviation between the feedback voltage and the reference voltage to adjust the output voltage, while keeping the equivalent resistance of the offset adjustment unit constant during the adjustment process.

[0016] The embodiments of the present invention have at least the following beneficial effects:

[0017] This invention provides a voltage divider feedback circuit with adjustment function, its voltage regulation method, and a switching power supply. In the voltage divider feedback circuit, an upper voltage divider network and a lower voltage divider network are connected in series between the output terminal and the reference ground as the main voltage divider path, used to adjust the overall voltage division ratio of the voltage divider feedback circuit, thereby setting the output voltage level. An offset adjustment unit, connected in parallel with the lower voltage divider network outside the main voltage divider path, obtains the required feedback voltage from its feedback node at the input terminal of the error amplifier to adjust the output voltage offset. Since only the resistive voltage division ratio of the offset adjustment unit is changed during the adjustment process without changing its total equivalent resistance, the overall voltage division ratio of the voltage divider feedback circuit is not affected. This achieves functional separation of output voltage level setting and accuracy calibration, allowing the main voltage divider path to handle the setting of different output voltage levels, while the offset adjustment unit is dedicated to compensating for systematic deviations. The two functions do not interfere with each other, significantly improving the flexibility of circuit design and control accuracy.

[0018] Furthermore, the offset adjustment unit is internally divided into upper and lower equivalent resistances by the feedback node. By switching internal connection nodes, the voltage division ratio of the resistors is adjusted to change the proportional relationship between the feedback voltage and the output voltage, thereby achieving fine adjustment of the output voltage and improving the output accuracy of the power supply system. Moreover, during the adjustment process, the changes in the upper and lower equivalent resistances are equal in magnitude and opposite in direction, ensuring that the total equivalent resistance of the offset adjustment unit remains constant. That is, when adjusting the voltage division ratio during the adjustment process, the output voltage level remains unchanged. Thus, offset adjustment of the output voltage is completed without changing the output voltage level, further guaranteeing adjustment accuracy.

[0019] Furthermore, the offset adjustment unit compensates for the voltage deviation between the feedback voltage and the reference voltage caused by the offset of the error amplifier or the offset of the reference voltage due to process variations, temperature drift, or circuit non-ideals, thereby compensating for the output voltage offset. Moreover, when switching output voltage levels, the resistor division ratio of the offset adjustment unit remains unchanged, meaning the accuracy deviation percentage is the same across different output voltage levels. Therefore, only one adjustment is needed to adapt to different output voltage levels. This adjustment process is performed once and locked after chip manufacturing, applicable to all configurable output voltage levels. The adjustment result does not become invalid with changes in the equivalent resistance of the upper and / or lower voltage divider networks, ensuring consistent output voltage accuracy across different voltage levels and providing high accuracy consistency for multi-level applications. Users do not need to repeat calibration in subsequent use, regardless of the voltage mode switched to, significantly reducing production testing costs and time, and improving mass production efficiency.

[0020] Furthermore, due to the adoption of a parallel adjustment architecture, the offset adjustment unit is connected as an independent branch, without changing the topology of the original main voltage divider path, which facilitates compatibility and integration with existing power management circuits. This structure is particularly suitable for high-precision, multi-level output DC-DC converters, achieving high-precision voltage adjustment without adding complex control logic, significantly improving the accuracy and consistency of power output.

[0021] It should be noted that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the present invention. Attached Figure Description

[0022] Figure 1 A schematic circuit diagram of a prior art voltage divider feedback circuit is shown;

[0023] Figure 2 A schematic circuit block diagram of a switching power supply and a voltage divider feedback circuit with adjustment function according to an embodiment of the present invention is shown.

[0024] Figure 3 A schematic circuit diagram of a voltage divider feedback circuit with adjustment function according to an embodiment of the present invention is shown;

[0025] Figure 4 A schematic flowchart of a voltage regulation method for a voltage divider feedback circuit with adjustment function according to an embodiment of the present invention is shown. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in various forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0027] Figure 2 A schematic circuit block diagram of a switching power supply and a voltage divider feedback circuit with adjustment function according to an embodiment of the present invention is shown.

[0028] like Figure 2As shown, the switching power supply 10 of this embodiment includes: a power circuit 20, a control circuit 21 for the power circuit 20, a voltage divider feedback circuit 100 with adjustment function, and an error amplifier EA. The power circuit 20 converts the input voltage VIN into an output voltage VO. Internally, it includes a switching transistor, an inductor, and an output capacitor. The topology of the power circuit 20 includes buck, boost, buck-boost, or flyback topologies. Power circuits are, for example, common DC-DC converters, and their circuit structures will not be specifically described here. The control circuit 21 adjusts the operating state of the switching transistors inside the power circuit 20 to regulate the output voltage VO. The voltage divider feedback circuit 100 with adjustment function performs voltage divider sampling on the output voltage VO. It is connected between the output terminal of the power circuit 20 and the reference ground GND, and generates a feedback voltage FB characterizing the output voltage VO. The output voltage VO is then precisely adjusted by fine-tuning the feedback voltage FB. Error amplifier EA receives feedback voltage FB at its first input and a set reference voltage VREF at its second input. Its output is connected to the control terminal of power circuit 20, providing an error amplification signal Vcom to control circuit 21. Control circuit 21 adjusts the operating state of the internal circuitry of power circuit 20 accordingly to regulate the output voltage VO, achieving closed-loop regulation. That is, error amplifier EA adjusts the error amplification signal Vcom based on the error amplification result between the feedback voltage FB and the reference voltage VREF, while control circuit 21 further adjusts the operating state of power circuit 20 based on the error amplification signal Vcom to stabilize the output voltage VO. For example, the first output of error amplifier EA can be an inverting input, while the second input can be a non-inverting input.

[0029] The voltage divider feedback circuit 100 with adjustment function in this embodiment is used to adjust the output voltage VO at the output terminal of the power circuit 20, set the output voltage level, and adjust the offset of the output voltage VO. Specifically, the voltage divider feedback circuit 100 includes an upper voltage divider network 110 and a lower voltage divider network 120 connected in series between the output terminal and the reference ground. The common node of the two is the voltage divider node, and the voltage of the voltage divider node is the output voltage divider voltage VOX. That is, the upper voltage divider network 110 is connected between the output terminal and the voltage divider node, and the lower voltage divider network 120 is connected between the voltage divider node and the reference ground. The upper voltage divider network 110 and the lower voltage divider network 120 constitute the main voltage divider path in this embodiment. The voltage divider feedback circuit 100 also includes an offset adjustment unit 130 connected between the voltage divider node and the ground terminal, that is, the offset adjustment unit 130 is connected in parallel with the lower voltage divider network 120. The offset adjustment unit 130 has a feedback node that provides a feedback voltage FB, and the feedback node is used to limit the resistive voltage division ratio of the offset adjustment unit 130. In this embodiment, the feedback voltage FB is provided to the first input terminal of the error amplifier EA. The voltage divider feedback circuit 100 sets the output voltage level by adjusting the equivalent resistance of the upper voltage divider network 110 and / or the lower voltage divider network 120, and adjusts the output voltage VO of the selected level by adjusting the resistor voltage division ratio, and the equivalent resistance of the offset adjustment unit 130 remains constant during the adjustment process.

[0030] When switching output voltage levels is required, the voltage division ratio is changed by adjusting the resistance of the main voltage divider path. For example, adjusting only the equivalent resistance of the upper voltage divider network 110 or the lower voltage divider network 120, or simultaneously adjusting the equivalent resistances of both the upper and lower voltage divider networks 110 and 120, thereby adjusting the output voltage VOX and setting different output voltage levels. When performing precision adjustment at a specific level, the output voltage VOX is finely adjusted by adjusting the resistor division ratio of the offset adjustment unit 130, thereby compensating for the offset error in the feedback loop and ensuring the accuracy of the output voltage VO. However, the equivalent resistance of the offset adjustment unit 130 is not changed during the adjustment process. Furthermore, the upper voltage divider network 110, the lower voltage divider network 120, and the offset adjustment unit 130 are all resistor networks, and the equivalent resistance of each resistor network remains constant during the adjustment process. Therefore, since only the voltage division ratio of the resistors is adjusted during the adjustment process, without changing the total equivalent resistance of the offset adjustment unit 130, the total equivalent resistance at both ends of the voltage divider node remains unchanged. This adjustment method does not change the voltage division ratio of the main voltage divider path, and the output voltage VOX will not change due to the resistance value of the main voltage divider path, thus not affecting the set output voltage level. This ensures that the consistency of the voltage division ratio between different output levels is not affected by the adjustment operation. It achieves decoupled control of output voltage level adjustment and precision adjustment, ensuring both the flexibility of multi-level output and high-precision voltage output at each level.

[0031] Furthermore, since the factors causing offset are the same across the same switching power supply 10, a single adjustment can compensate for the same offset error across all voltage levels, eliminating the need for individual adjustments for each level. Therefore, the single adjustment result of the offset adjustment unit 130 is applicable to all configurable output voltage levels and does not fail with changes in the equivalent resistance of the upper voltage divider network 110 and / or the lower voltage divider network 120. That is, when switching between different output voltage levels, the resistor voltage division ratio already adjusted by the offset adjustment unit 130 remains unchanged; and when adjusting the resistor voltage division ratio during a single adjustment, the set output voltage level remains unchanged. Thus, after leaving the factory, only one offset adjustment parameter setting is required to achieve accuracy calibration across all output levels, significantly simplifying the debugging steps in the production process and reducing testing costs. Simultaneously, since repeated adjustments between different levels are unnecessary, the cumulative error caused by multiple adjustments is avoided, further improving the overall stability and reliability of the system.

[0032] Figure 3 A schematic circuit diagram of a voltage divider feedback circuit with adjustment function according to an embodiment of the present invention is shown.

[0033] like Figure 3 As shown, the equivalent resistance of the upper voltage divider network 110 can be considered as an adjustable resistor R1, and the equivalent resistance of the lower voltage divider network 120 can be considered as an adjustable resistor R4. The offset adjustment unit 130 is divided by the feedback node into an upper equivalent resistance near the voltage divider node and a lower equivalent resistance near the reference ground. The upper equivalent resistance can be considered as an adjustable resistor R2, and the lower equivalent resistance can be considered as an adjustable resistor R3. The adjustable resistors R2 and R3 are connected in series to form the offset adjustment unit 130, and their common node is the feedback node, providing the feedback voltage FB. The resistor voltage division ratio mentioned in this embodiment is the ratio of the upper equivalent resistance to the lower equivalent resistance. Therefore, by adjusting the resistance ratio of the adjustable resistors R2 and R3, the ratio between the feedback voltage FB and the output voltage divider VOX can be changed, thereby achieving fine adjustment of the output voltage VO.

[0034] In this embodiment, the upper voltage divider network 110, the lower voltage divider network 120, and the offset adjustment unit 130 are all resistor networks, and each resistor network consists of several resistors and several switches. By controlling the conduction state of different switches, the equivalent resistance of the upper voltage divider network 110 or the lower voltage divider network 120, as well as the voltage division ratio of the offset adjustment unit 130, can be adjusted. The switches used here can include mechanical switches, fuses, relays, or transistors, etc. Therefore, the upper voltage divider network 110 and the lower voltage divider network 120 can have many circuit implementations, which will not be listed here. Figure 3The diagram only illustrates the use of adjustable resistors R1 and R4. Similarly, the offset adjustment unit 130 can have many circuit configurations, and can be composed of separate adjustable resistors R2 and R3, with their respective resistance values ​​adjusted when adjusting the voltage division ratio; or it can consist of a single adjustable resistor, with the resistance distribution between the upper and lower parts adjusted by changing the position of its internal taps when adjusting the voltage division ratio. Specific circuit connections will not be detailed here; only the structure of adjustable resistors R2 and R3 is shown. The adjustment and control circuits for each equivalent resistance are also not specifically shown here.

[0035] As mentioned above, the total equivalent resistance must remain constant during the adjustment of the voltage division ratio. Therefore, the resistance adjustments of the upper and lower equivalent resistances are equal in magnitude and opposite in direction, ensuring that the equivalent resistance of the offset correction unit 130 remains constant. That is, when the adjustable resistor R3 increases by ΔR, the adjustable resistor R2 decreases by ΔR accordingly.

[0036] Furthermore, the offset adjustment unit 130 is used to compensate for the output voltage VO offset caused by the voltage deviation Vos between the feedback voltage FB and the reference voltage VREF due to process deviations, temperature drift, stress, or circuit structure deviations. This voltage deviation Vos can include the offset of the error amplifier EA and the offset of the reference voltage VREF. Moreover, this voltage deviation Vos has a proportional relationship with the resistance adjustment amount ΔR of the upper or lower equivalent resistor. The voltage divider feedback circuit 100 can adjust the resistor division ratio according to this proportional relationship, which is related, for example, to the reference voltage VREF and the resistance value of the lower equivalent resistor before adjustment. After adjusting the equivalent resistance of the upper voltage divider network 110 and / or the lower voltage divider network 120 to select the output voltage level, the ratio between the feedback voltage FB and the unadjusted output voltage VO is used as the voltage division coefficient Kf. If the ratio between the reference voltage VREF and the unadjusted output voltage VO is not equal to this voltage division coefficient Kf, it indicates that the output voltage is offset. Therefore, by adjusting the resistance values ​​of adjustable resistors R2 and R3, after adjustment, the ratio of the set reference voltage VREF to the adjusted output voltage VO2 can be made into the voltage divider coefficient Kf, thus achieving the ideal adjustment effect.

[0037] Although both adjustable resistors R1 and R4 can be used to adjust the voltage division ratio, to further ensure circuit stability, this embodiment will use adjusting only adjustable resistor R4 to adjust the voltage division ratio as an example. For instance, at a specific output voltage level, the equivalent resistance of the lower voltage divider network 120 is set to R4, the equivalent resistance of the upper voltage divider network 110 is set to R1, and the equivalent resistances of the upper and lower equivalent resistors in the offset correction unit 130 are set to R2 and R3, respectively. Here, R1, R2, R3, and R4 all represent specific resistance values. At this point, according to... Figure 3The circuit connection shown holds the following relationship:

[0038] Formula 1

[0039] Formula 2

[0040] That is, the output voltage divider VOX and the feedback voltage FB have a certain proportional relationship, and the output voltage VO and the output voltage divider VOX also have a certain proportional relationship. Therefore, the output voltage VO and the feedback voltage FB have a certain proportional relationship. Without considering the offset caused by process deviations, temperature drift, stress, or circuit structure deviations, after passing through the error amplifier EA, according to the characteristics of the error amplifier EA, we should have FB = VREF. Substituting this relationship into Equations 1 and 2, we get the following relationship:

[0041] Formula 3

[0042] Formula 4

[0043] Formulas 3 and 4 above represent the output voltage and output voltage divider values ​​under ideal conditions without offset. Therefore, the output voltage divider VOX is determined by (1 + R2 / R3) × VREF. However, due to offset, formulas 3 and 4 do not hold true, thus requiring adjustment. According to formula 3, we only need to modify the values ​​of R2 / R3 based on the magnitude of the offset voltage Vos, i.e., modify the resistor voltage divider ratio, to obtain a precise output voltage divider VOX. Assuming the voltage offset Vos includes the offset of the error amplifier and the offset of the reference voltage, we have Vos = EA offset + VREF offset, and Vos = VREF - FB, i.e., FB = VREF - Vos. Substituting these into formula 1, we get:

[0044] Formula 5

[0045] After adjusting the voltage division ratio of the offset correction unit 130, the resistance values ​​of the upper equivalent resistance and the lower equivalent resistance are R2-ΔR and R3+ΔR, respectively. Therefore, after correction, we can obtain:

[0046] Formula 6

[0047] That is, the adjusted output voltage VOX2 should have an ideal proportional relationship with the reference voltage VREF. Similarly, the adjusted output voltage VO2 can also be expressed by the formula:

[0048] Formula 7

[0049] Furthermore, as described above, the adjusted output voltage VO2 is proportional to the reference voltage VREF, that is:

[0050] Formula 8

[0051] Right now, Formula 9

[0052] Therefore, the value of the voltage divider coefficient Kf is clear. After adjustment, the ratio of the reference voltage VREF to the adjusted output voltage VO2 is the voltage divider coefficient Kf, achieving the ideal adjustment effect. Based on the equations in Formulas 7 and 8, we can also obtain:

[0053] Formula 10

[0054] Therefore, there is a specific proportional relationship between the resistance adjustment amount ΔR and the voltage deviation Vos. So, the mapping relationship between the resistance adjustment amount and the voltage deviation can be preset and stored. When adjusting the output voltage level later, the corresponding resistance adjustment amount ΔR can be obtained directly according to the deviation voltage Vos, and then the voltage division ratio of the resistor can be directly adjusted to complete the adjustment.

[0055] Figure 4 A schematic flowchart of a voltage regulation method for a voltage divider feedback circuit with adjustment function according to an embodiment of the present invention is shown.

[0056] This voltage regulation method is applied in the aforementioned switching power supply and voltage divider feedback circuit to adjust the output voltage at the output terminal of the power circuit. See also... Figure 4 The voltage regulation method in this embodiment includes, for example, the following steps:

[0057] In step S101, the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network is adjusted to set the output voltage level.

[0058] In step S102, the feedback voltage and the set reference voltage are passed through an error amplifier to generate an error amplification signal that is provided to the power circuit so as to stabilize the output voltage.

[0059] Through the above two steps, when the output voltage level needs to be adjusted, the voltage division ratio is adjusted by adjusting the equivalent resistance of the upper voltage divider network 110 and / or the lower voltage divider network 120, thereby accurately setting the output voltage level. Then, through the following step S103, the offset adjustment unit 130 is used to compensate for voltage offset caused by process deviations and temperature drift.

[0060] In step S103, the voltage division ratio of the resistor is adjusted according to the voltage deviation between the feedback voltage and the reference voltage to adjust the output voltage, and the equivalent resistance of the offset adjustment unit is kept constant during the adjustment process.

[0061] According to the above formula, there is a proportional relationship between the voltage deviation and the resistance adjustment amount of the upper or lower equivalent resistance. Therefore, the mapping relationship between the voltage deviation and the resistance adjustment amount can be preset so that the voltage divider feedback circuit 100 adjusts the resistance voltage division ratio according to the mapping relationship, so that the ratio between the adjusted output voltage VO and the set reference voltage VREF is the set value 1 / Kf.

[0062] The voltage regulation method in this embodiment is based on the aforementioned voltage divider feedback circuit and switching power supply. The specific circuit principle, structure, and operation process are described above. Figure 2 and Figure 3 The examples have already been described, so they will not be repeated here.

[0063] It should be noted that the numerical values ​​in this article are for illustrative purposes only. In other embodiments of the present invention, other numerical values ​​may be sampled to implement this solution. The specific values ​​should be reasonably set according to the actual situation, and the present invention does not limit them.

[0064] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

[0065] It should also be understood that the terminology and expressions used herein are for descriptive purposes only, and one or more embodiments described herein should not be limited to these terms and expressions. The use of these terms and expressions does not exclude any illustrative and descriptive equivalent features (or parts thereof), and it should be recognized that various modifications that may exist should also be included within the scope of the claims. Other modifications, variations, and substitutions may also exist. Accordingly, the claims should be considered to cover all such equivalents.

Claims

1. A voltage divider feedback circuit with adjustment function, used to regulate the output voltage at the output terminal of a power circuit, wherein, The voltage divider feedback circuit includes: An upper voltage divider network is connected between the output terminal and the voltage divider node; A voltage divider network is connected between the voltage divider node and the reference ground; and An offset correction unit, connected in parallel with the lower voltage divider network, is provided with a feedback node that provides a feedback voltage. The feedback node limits the resistive voltage division ratio of the offset correction unit. The voltage divider feedback circuit sets the output voltage level by adjusting the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network, and adjusts the output voltage of the selected level by adjusting the voltage division ratio of the resistors, while the equivalent resistance of the offset adjustment unit remains constant during the adjustment process.

2. The voltage divider feedback circuit according to claim 1, wherein, The upper voltage divider network, the lower voltage divider network, and the offset adjustment unit are all resistor networks, and the equivalent resistance of each resistor network remains constant during the adjustment process.

3. The voltage divider feedback circuit according to claim 1, wherein, When switching the output voltage level, the voltage division ratio of the resistor in the offset adjustment unit remains unchanged; and when adjusting the voltage division ratio during the adjustment process, the output voltage level remains unchanged.

4. The voltage divider feedback circuit according to claim 1, wherein, The offset correction unit is divided by the feedback node into an upper equivalent resistance near the voltage divider node and a lower equivalent resistance near the reference ground. The voltage division ratio is the ratio of the upper equivalent resistance to the lower equivalent resistance. During the adjustment of the voltage division ratio of the resistors, the resistance adjustment amounts of the upper equivalent resistor and the lower equivalent resistor are equal in magnitude and opposite in direction, so that the equivalent resistance of the offset adjustment unit remains constant.

5. The voltage divider feedback circuit according to claim 4, wherein, The feedback voltage and the set reference voltage are compared by an error amplifier to obtain an error amplification signal provided to the power circuit. The offset adjustment unit is used to compensate for the output voltage offset caused by the voltage deviation between the feedback voltage and the reference voltage, the voltage deviation including the offset of the error amplifier and the offset of the reference voltage.

6. The voltage divider feedback circuit according to claim 5, wherein, After adjusting the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network to select the output voltage level, the ratio between the feedback voltage and the unadjusted output voltage is used as the voltage divider coefficient. The voltage divider feedback circuit is adjusted so that the ratio between the set reference voltage and the adjusted output voltage is used as the voltage divider coefficient.

7. The voltage divider feedback circuit according to claim 5, wherein, The voltage deviation is proportional to the resistance adjustment of the upper or lower equivalent resistor. The voltage divider feedback circuit adjusts the voltage division ratio according to the proportional relationship. The proportional relationship is related to the reference voltage and the resistance value of the lower equivalent resistor before adjustment.

8. The voltage divider feedback circuit according to claim 2, wherein, Each of the resistor networks consists of several resistors and several switches. The equivalent resistance of the upper voltage divider network or the lower voltage divider network and the voltage division ratio of the resistors are adjusted by controlling the on state of different switches. The switches include fuses, relays or transistors.

9. A switching power supply, comprising: Power circuits are used to convert input voltage into output voltage. The voltage divider feedback circuit as described in any one of claims 1 to 8 is connected between the output terminal of the power circuit and the reference ground to generate a feedback voltage; as well as An error amplifier has a first input terminal receiving the feedback voltage, a second input terminal receiving a set reference voltage, and its output terminal connected to the control circuit of the power circuit to provide an error amplification signal. The error amplifier adjusts the error amplification signal based on the difference between the feedback voltage and the reference voltage, and the control circuit adjusts the operating state of the power circuit based on the error amplification signal to stabilize the output voltage.

10. The switching power supply according to claim 9, wherein, The power circuit includes a switching transistor, an inductor, and an output capacitor. The topology of the power circuit includes buck, boost, buck-boost, or flyback topologies.

11. A voltage regulation method for a voltage divider feedback circuit with adjustment function, used to adjust the output voltage at the output terminal of a power circuit, wherein, The voltage divider feedback circuit includes an upper voltage divider network and a lower voltage divider network connected in series between the output terminal and the reference ground, and an offset adjustment unit connected in parallel with the lower voltage divider network. The offset adjustment unit has a feedback node that provides a feedback voltage, and the feedback node limits the resistive voltage division ratio of the offset adjustment unit. The voltage adjustment method includes: Adjust the equivalent resistance of the upper voltage divider network and / or the lower voltage divider network to set the output voltage level; The feedback voltage and the set reference voltage are passed through an error amplifier to generate an error amplification signal, which is then provided to the power circuit to stabilize the output voltage; and The voltage division ratio of the resistor is adjusted according to the voltage deviation between the feedback voltage and the reference voltage to adjust the output voltage, and the equivalent resistance of the offset adjustment unit is kept constant during the adjustment process.

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