A method for selecting feedback resistors for switching power supplies

Abstract

The present invention relates to the technical field of switch circuit design, and provides a method for selecting a feedback resistor of a switch power supply. A database is referenced to determine a resistor list, a corresponding circuit mode is set according to a preset feedback circuit, and then a corresponding mode calculation formula can be determined. When selecting the feedback resistor of the switch power supply, a first feedback resistor is selected from the resistor list according to the obtained target calculation parameters and calculation mode, and the corresponding mode calculation formula is substituted, so that the target resistance range of other feedback resistors matching the first feedback resistor can be quickly determined, and other feedback resistors can be determined from the resistor list according to the target resistance range; at this time, according to the preset calculation rules, the comprehensive utilization rate of each group of "first feedback resistor + other feedback resistors" can be calculated, and a comprehensive recommendation list can be obtained and output, so as to automatically provide the most suitable feedback resistor to the user, and the computer program is used for calculation, so as to further save the time of selection.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to a method for selecting a feedback resistor of a switching power supply. Background Art

[0002] With the rapid development of electronic technology, the relationship between electronic equipment and people's work and life is becoming increasingly close, and electronic equipment cannot do without a reliable power supply. In the 1980s, computer power supplies were fully realized as switching power supplies, and the power supply replacement of computers was completed first. In the 1990s, switching power supplies entered various electronic and electrical equipment fields one after another. Program-controlled switches, communications, electronic testing equipment power supplies, control equipment power supplies, etc. have all widely used switching power supplies, which has promoted the rapid development of switching power supply technology.

[0003] Compared with switching power supplies and linear power supplies, the cost of both increases with the increase of output power, but the growth rates of the two are different. At a certain output power point, the cost of linear power supplies is higher than that of switching power supplies. With the development and innovation of power electronics technology, switching power supply technology is constantly innovating, and this cost reversal point is increasingly moving towards the low output power end, which provides a wide range of development space for switching power supplies.

[0004] The high frequency of switching power supply is its development direction. High frequency makes the switching power supply smaller and allows the switching power supply to enter a wider range of applications, especially in the field of high-tech, which promotes the miniaturization and lightness of high-tech products. In addition, the development and application of switching power supply are of great significance in security monitoring, energy saving, resource saving and environmental protection.

[0005] Currently, the output voltage of a switching power supply is set by the feedback resistance value, and it takes a lot of time to select a suitable resistance when selecting the feedback resistance.

[0006] like Figure 1 , the feedback resistor is divided into upper resistor R(up) and lower resistor R(dn). Where VOUT is the output voltage, VFB is the feedback voltage, and the feedback formula is as follows:

[0007] Summary of the invention

[0008] The present invention provides a method for selecting a feedback resistor of a switching power supply, which solves the technical problem that the existing switching power supply circuit design relies on manual selection and lacks effective technical means to quickly determine the feedback resistor.

[0009] In order to solve the above technical problems, the present invention provides a method for selecting a feedback resistor of a switching power supply, comprising the steps of:

[0010] S1. Generate a resistance list according to the database, and set the corresponding circuit mode according to the preset feedback circuit;

[0011] S2, obtaining target calculation parameters of the switching power supply circuit and receiving a calculation mode;

[0012] S3, determining target resistance value information according to the calculation mode and the target calculation parameters;

[0013] S4. Calculate the comprehensive utilization rate according to the preset calculation rules and the target resistance information, integrate and obtain a comprehensive recommendation list and output it.

[0014] This basic solution refers to a database to determine a resistor list, sets a corresponding circuit mode according to a preset feedback circuit, and then determines a corresponding mode calculation formula. When selecting the feedback resistor of the switching power supply, the first feedback resistor is selected from the resistor list according to the obtained target calculation parameters and calculation mode, and the corresponding mode calculation formula is substituted. The target resistance range of other feedback resistors matching the first feedback resistor can be quickly determined, and other feedback resistors can be determined from the resistor list according to the target resistance range. At this time, according to the preset calculation rules, the comprehensive utilization rate of each group of "first feedback resistor + other feedback resistors" can be calculated, and a comprehensive recommendation list can be obtained and output, so as to automatically provide the most suitable feedback resistor to the user, and use computer program calculation to further save the selection time.

[0015] In a further embodiment, in step S1,

[0016] The generating of the resistor list according to the database specifically comprises: collecting the serial number, resistance value and usage frequency of each resistor in the database to generate the resistor list;

[0017] The circuit mode corresponding to the preset feedback circuit setting is specifically: setting the selectable circuit mode according to the feedback resistance mode of the switching power supply.

[0018] This solution introduces the usage frequency of each resistor in the conventional resistor list to calculate the comprehensive usage rate as the basis for recommended sorting. It is a further judgment of the user's usage habits based on historical data, so that the selection of feedback resistors can be more intelligent.

[0019] In a further embodiment, in step S2:

[0020] The target calculation parameters include output voltage, output voltage error coefficient, and feedback voltage;

[0021] The calculation mode includes a single-selection mode and a global mode. The single-selection mode is to select any one of the circuit modes for calculation, and the global mode is to calculate each of the circuit modes.

[0022] This solution sets up two calculation modes (single selection mode and global mode), which provide targeted selection services for different customer needs and can also reduce the equipment operation load.

[0023] In a further embodiment, step S3 comprises:

[0024] S31, selecting the corresponding circuit mode according to the calculation mode;

[0025] S32, reading each resistor in the resistor list as a first feedback resistor according to a preset reading order, and substituting the target calculation parameter into a corresponding mode calculation formula to obtain a calculation range value;

[0026] S33, traversing the resistance list to obtain target resistance information that meets the calculation range value;

[0027] The target resistance information is independent resistance information or series resistance group information.

[0028] When determining the circuit mode corresponding to the calculation mode, this scheme can further determine the corresponding mode calculation formula. At this time, the resistance list is read according to the preset reading order, the first feedback resistor is substituted into the mode calculation formula to obtain the calculation range value, and the resistance list is traversed to filter out the target resistance information that meets the requirements. In this way, the resistances contained in the entire resistance list can be covered, and all resistance groups that meet the requirements can be filtered out.

[0029] In a further embodiment, step S4 comprises:

[0030] S41, substituting the resistance information of the first feedback resistor and the target resistance information into a preset calculation rule to calculate the comprehensive utilization rate of the feedback resistor group;

[0031] S42: According to a preset sorting rule, the comprehensive usage rate is counted to obtain a comprehensive recommendation list and output it.

[0032] In a further embodiment, the step S42 is specifically:

[0033] When the calculation mode is a single-selection mode, the comprehensive utilization rate of each feedback resistor group in the currently selected circuit mode is obtained, and a comprehensive recommendation list is obtained and output according to a preset sorting rule;

[0034] When the calculation mode is a global mode, the comprehensive utilization rate of each feedback resistor group in each circuit mode is obtained, and a comprehensive recommendation list is obtained and output according to a preset sorting rule.

[0035] When determining the first feedback resistor and other feedback resistors, this solution calculates the comprehensive usage rate of the feedback resistor group and uses this as the basis for sorting the comprehensive recommendation list, which can further fit the user's usage habits.

[0036] In a further embodiment, the preset sorting rule is:

[0037] A. sorting the obtained comprehensive utilization rates for the first time in order from high to low;

[0038] B. When there are the same comprehensive utilization rates, the corresponding variances are calculated, and the same comprehensive utilization rates are ranked according to the size of the variances;

[0039] C. When the same comprehensive utilization rate and the same variance exist, the resistance value of the resistor with the lowest frequency of use in the corresponding feedback resistor group is obtained as the judgment resistance value, and the same comprehensive utilization rates are ranked according to the size of the judgment resistance value.

[0040] This solution sets a preset sorting rule, sets the comprehensive utilization rate, the comprehensive utilization rate variance, and the resistance value of the resistor with the lowest frequency of use as a progressive sorting basis, and can effectively select a commonly used feedback resistor group.

[0041] In a further embodiment, the comprehensive usage rate is an average value of the usage frequency of the feedback resistor group.

[0042] In a further embodiment, the circuit mode includes a first mode, a second mode, and a third mode;

[0043] The first mode is that the feedback resistor group includes a pull-up resistor and a pull-down resistor;

[0044] The second mode is that the feedback resistor group includes two pull-up resistors and one pull-down resistor;

[0045] The third mode is that the feedback resistor group includes one pull-up resistor and two pull-down resistors.

[0046] In a further embodiment, in the first mode, a pull-up resistor or a pull-down resistor is selected as the first feedback resistor;

[0047] In the second mode, a pull-down resistor is selected as the first feedback resistor;

[0048] In the third mode, a pull-up resistor is selected as the first feedback resistor.

[0049] This solution selects an independent resistor as the first feedback resistor (not connected in series with other feedback resistors), which can reduce the difficulty of calculation, improve calculation efficiency, and thus improve selection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a working flow chart of a method for selecting a feedback resistor of a switching power supply provided by an embodiment of the present invention;

[0051] Figure 2 is a list of resistors provided by an embodiment of the present invention;

[0052] Figure 3 is a circuit structure diagram of a first mode provided by an embodiment of the present invention;

[0053] Figure 4 is a circuit structure diagram of a second mode provided by an embodiment of the present invention;

[0054] Figure 5 is a circuit structure diagram of a second mode provided by an embodiment of the present invention;

[0055] Figure 6 It is a schematic diagram of an operation panel corresponding to a method for selecting a feedback resistor of a switching power supply provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0057] The embodiment of the present invention provides a method for selecting a feedback resistor of a switching power supply, such as Figure 1 As shown, in this embodiment, steps S1 to S4 are included:

[0058] S1. Generate a resistor list according to the database, and set a corresponding circuit mode according to a preset feedback circuit.

[0059] In this embodiment, see Figure 2 , generating a resistor list according to the database is specifically as follows: counting the serial number, resistance value, and usage frequency S(Rk) of each resistor in the database (where k=1,2,3…n, and n represents the total number of resistors) to generate a resistor list;

[0060] The circuit mode corresponding to the preset feedback circuit setting is specifically: the selectable circuit mode is set according to the VB feedback resistance mode of the switching power supply.

[0061] In this embodiment, the circuit mode includes a first mode (eg Figure 6 Mode A in the second mode (e.g. Figure 6 Mode B in the third mode (e.g. Figure 6 One or more of the modes C);

[0062] See also Figure 3 , the first mode is that the feedback resistor group includes a pull-up resistor R(up) and a pull-down resistor R(dn);

[0063] See also Figure 4 , the second mode is that the feedback resistor group includes two pull-up resistors R1(up), R2(up) and one pull-down resistor R(dn);

[0064] See also Figure 5 In the third mode, the feedback resistor group includes a pull-up resistor R(up) and two pull-down resistors R2(dn) and R3(dn).

[0065] This embodiment introduces the usage frequency of each resistor in the conventional resistor list to calculate the comprehensive usage rate as the basis for recommendation sorting. It is a further judgment of the user's usage habits based on historical data, so that the selection of feedback resistors can be more intelligent.

[0066] S2. Obtain target calculation parameters of the switching power supply circuit and receive a calculation mode.

[0067] In this embodiment, the target calculation parameters include the output voltage Vout, the output voltage error coefficient r, and the feedback voltage Vfb; wherein, the output voltage Vout and the output voltage error coefficient r are input according to the design requirements, for example, the output voltage is set to 3.3V, the error coefficient is 1%, and the output voltage is 3.3V+ / -1%; the feedback voltage is obtained according to the specification of the DC-DC chip used, for example, Vfb=0.6V.

[0068] In addition, other corresponding parameters can be set according to actual conditions.

[0069] The calculation modes include single-select mode and global mode. The single-select mode is to select any circuit mode for calculation and determine the optimal solution; the global mode is to calculate each circuit mode and determine the optimal solution.

[0070] This embodiment sets two calculation modes (single-selection mode and global mode), which provide targeted selection services for different customer needs and can also reduce the equipment operation load.

[0071] S3, determining target resistance information according to the calculation mode and target calculation parameters, including steps S31 to S33:

[0072] S31, selecting a corresponding circuit mode according to the calculation mode;

[0073] S32 . According to a preset reading order, read each resistor in the resistor list as a first feedback resistor, and substitute the target calculation parameter into a corresponding mode calculation formula to obtain a calculation range value.

[0074] In this embodiment, in the first mode, a pull-up resistor or a pull-down resistor is selected as the first feedback resistor;

[0075] In the second mode, the pull-down resistor is selected as the first feedback resistor;

[0076] In the third mode, the pull-up resistor is selected as the first feedback resistor.

[0077] In this embodiment, an independent resistor is selected as the first feedback resistor (not connected in series with other feedback resistors), which can reduce the difficulty of calculation, improve the calculation efficiency, and thus improve the selection efficiency.

[0078] S33, traverse the resistance list to obtain target resistance information that meets the calculation range value;

[0079] The target resistance information is independent resistance information or series resistance group information.

[0080] When determining the circuit mode corresponding to the calculation mode, this embodiment can further determine the corresponding mode calculation formula. At this time, the resistance list is read according to the preset reading order, the first feedback resistor is substituted into the mode calculation formula to obtain the calculation range value, and the resistance list is traversed to filter out the target resistance information that meets the requirements. In this way, the resistances contained in the entire resistance list can be covered, and all resistance groups that meet the requirements can be filtered out.

[0081] S4, calculating the comprehensive utilization rate according to the preset calculation rules and the target resistance information, integrating and obtaining a comprehensive recommendation list and outputting it, including steps S41~S42:

[0082] S41, substituting the resistance information of the first feedback resistor and the target resistance information into a preset calculation rule to calculate the comprehensive utilization rate of the feedback resistor group;

[0083] In this embodiment, the comprehensive usage rate is the average value of the usage frequency of the feedback resistor group.

[0084] S42. According to the preset sorting rules, the comprehensive usage rate is counted to obtain a comprehensive recommendation list and output it.

[0085] The comprehensive recommendation list mainly includes the selection results of the upper resistors (such as pull-up resistors and pull-down resistors) in each area, that is, the actual resistance values.

[0086] In this embodiment, when the calculation mode is the single-selection mode, the comprehensive utilization rate of each feedback resistor group in the currently selected circuit mode is obtained, and a comprehensive recommendation list is obtained and output according to the preset sorting rules;

[0087] When the calculation mode is the global mode, the comprehensive utilization rate of each feedback resistor group in each circuit mode is obtained, and a comprehensive recommendation list is obtained and output according to the preset sorting rules.

[0088] In this embodiment, when determining the first feedback resistor and other feedback resistors, the comprehensive usage rate of the feedback resistor group is calculated as the ranking basis of the comprehensive recommendation list, which can further conform to the user's usage habits.

[0089] In this embodiment, the preset sorting rules are:

[0090] A. Sort the obtained comprehensive utilization rates for the first time in descending order;

[0091] B. When there are the same comprehensive utilization rates, calculate the corresponding variance and rank the same comprehensive utilization rates according to the size of the variance;

[0092] C. When there are the same comprehensive utilization rate and the same variance, the resistance value of the resistor with the lowest frequency of use in the corresponding feedback resistor group is obtained as the judgment resistance value, and the same comprehensive utilization rate is ranked according to the size of the judgment resistance value.

[0093] This embodiment sets a preset sorting rule, and sets the comprehensive usage rate, the comprehensive usage rate variance, and the resistance value of the resistor with the lowest usage frequency as a progressive sorting basis, which can effectively select a commonly used feedback resistor group.

[0094] In the specific implementation process:

[0095] If the calculation mode is single selection mode:

[0096] Scenario 1: When the first mode is selected as the current circuit mode, each resistor in the resistor list may be read in sequence according to a preset reading order (eg, sequential order, reverse order) as the first feedback resistor, as a pull-up resistor or a pull-down resistor.

[0097] For example:

[0098] The first step is to read the resistor with serial number 1 (ie k=1) as the first feedback resistor R(up)k.

[0099] The model calculation formula is:

[0100]

[0101] Step 2: Substitute R(up)k, Vout, and Vfb into formula (1) to calculate the range of R(dn) [ ];

[0102]

[0103]

[0104] Step 3: At this time, traverse the resistor list to determine whether there is a resistor with a resistance value in [ ], if so, the corresponding resistance R(up)k, R(dn)k and the operating frequency SR(up)k, SR(dn)k are stored in array a[1], otherwise they are discarded.

[0105] This is done by analogy to obtain a[k] until it is determined that the currently read resistor Rk is the last one in the resistor list, then proceed to the next step, otherwise read the next resistor and repeat the above array calculation (i.e. return to the second step).

[0106] Step 4: Calculate the comprehensive utilization rate according to the preset calculation rules and the target resistance range. The comprehensive utilization rate of this feedback resistor group is:

[0107] S1(k)=[SR(up)k+SR(dn)k] / 2, k≤n;

[0108] Step 5. According to the preset sorting rules, the feedback resistor groups (each group SR(up)k, SR(dn)k) are sorted in descending order of comprehensive utilization rate to generate a comprehensive recommendation list and output it.

[0109] Scenario 2: When the second mode is selected as the current circuit mode, each resistor in the resistor list may be read in sequence according to a preset reading order (eg, sequential order, reverse order) as the first feedback resistor, and as the pull-down resistor.

[0110] For example:

[0111] The first step is to read the resistor with serial number 1 (ie k=1) as the first feedback resistor, namely resistor R(dn)k.

[0112] The model calculation formula is:

[0113]

[0114] Step 2: Substitute R(dn)k, Vout, and Vfb into formula (2) to calculate the range of R1(up) k+R2(up) k: [R1(up) +R2(up)]min, [R1(up) +R2(up)] ;

[0115]

[0116]

[0117] Step 3: From the circuit model, we know that R1(up) k and R2(up) k are equal, that is, the positions of R1(up) k and R2(up) k in the circuit can be exchanged; the maximum value of R1(up) k and R2(up) k is given by For example, if R(up)1+R(up)2∈[15k,17k], then the maximum value of R1(up) k and R2(up) k is 17k (because the minimum value of R(up)1 and R(up)2 can be 0Ω).

[0118] Therefore, traverse the resistor list to determine whether there is a resistance value in [0, ] interval (two series resistors), if so, store the corresponding resistances R1(up) k, R2(up) k, R(dn) k and the usage frequencies SR1(up) k, SR2(up) k, SR(dn) k into array b[1], otherwise discard them.

[0119] This is done by analogy to obtain b[k] until it is determined that the currently read resistor Rk is the last one in the resistor list, then proceed to the next step, otherwise read the next resistor and repeat the above array calculation (i.e. return to the second step).

[0120] Step 4: Calculate the comprehensive utilization rate according to the preset calculation rules and the target resistance range. The comprehensive utilization rate of this feedback resistor group is:

[0121] S2(k)=[SR1(up)k+SR2(up)k+SR(dn)k] / 3.

[0122] Step 5. According to the preset sorting rules, the feedback resistor groups (each group SR(up)k, SR1(up)k, SR2(dn)k) are sorted in descending order of comprehensive utilization rate to generate a comprehensive recommendation list b and output it.

[0123] Scenario 3: When the third mode is selected as the current circuit mode, each resistor in the resistor list may be read in sequence according to a preset reading order (eg, sequential order, reverse order) as the first feedback resistor, and as the pull-up resistor.

[0124] For example:

[0125] The first step is to read the resistor with serial number 1 (ie k=1) as the first feedback resistor, namely resistor R(up)k.

[0126] The model calculation formula is:

[0127]

[0128] Step 2: Substitute R(dn)k, Vout, and Vfb into formula (3) to calculate the range of R1(dn) k+R2(dn) k [R1(dn)+R2(dn)]min, [R1(dn)+R2(dn)] ;

[0129]

[0130]

[0131] Step 3: Similarly, at this time, traverse the resistor list to determine whether there is a resistance value in [0, ] interval (two series resistors), if so, store the corresponding resistances R(up) k, R1(dn) k, R2(dn) k and the usage frequencies SR(up) k, SR1(dn) k, SR2(dn) k into array c[1], otherwise discard them.

[0132] This is done by analogy to obtain c[k] until it is determined that the currently read resistor Rk is the last one in the resistor list, then proceed to the next step, otherwise read the next resistor and repeat the above array calculation (i.e. return to the second step).

[0133] Step 4: Calculate the comprehensive utilization rate according to the preset calculation rules and target resistance information, where the comprehensive utilization rate of this feedback resistor group is:

[0134] S3(k)=[SR(up)k+ SR1(dn)k +SR2(dn)k] / 3.

[0135] Step 5. According to the preset sorting rules, the feedback resistor groups (each group SR(up)k, SR1(up)k, SR2(dn)k) are sorted in descending order of comprehensive utilization rate to generate a comprehensive recommendation list c and output it.

[0136] If the calculation mode is global mode:

[0137] According to the steps of each of the above situations 1 to 3, the comprehensive utilization rates S1(k), S2(k), and S3(k) in the first mode, the second mode, and the third mode are calculated in single-selection mode, and the comprehensive utilization rates S1(k), S2(k), and S3(k) are sorted according to the preset sorting rules to generate a comprehensive recommendation list and output it. The final output result is shown in Figure 6 .

[0138] The embodiment of the present invention refers to a database to determine a resistor list, and sets a corresponding circuit mode according to a preset feedback circuit, thereby determining a corresponding mode calculation formula. When selecting a feedback resistor for a switching power supply, a first feedback resistor is selected from the resistor list according to the obtained target calculation parameters and calculation mode, and the corresponding mode calculation formula is substituted. The target resistance range of other feedback resistors matching the first feedback resistor can be quickly determined, and other feedback resistors can be determined from the resistor list according to the target resistance range. At this time, according to the preset calculation rules, the comprehensive utilization rate of each group of "first feedback resistor + other feedback resistors" can be calculated, and a comprehensive recommendation list can be obtained and output, so as to automatically provide the most suitable feedback resistor to the user, and the selection time can be further saved by using a computer program for calculation.

[0139] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for selecting feedback resistors for switching power supplies. It is characterized in that Includes steps: S1. Generate a resistance list according to the database, and set the corresponding circuit mode according to the preset feedback circuit; S2, obtaining target calculation parameters of the switching power supply circuit and receiving a calculation mode; S3, determining target resistance information according to the calculation mode and the target calculation parameters; S4, calculating the comprehensive utilization rate according to the preset calculation rules and the target resistance information, integrating and outputting a comprehensive recommendation list; In step S1, The generating of the resistor list according to the database specifically comprises: collecting the serial number, resistance value, and usage frequency of each resistor in the database to generate the resistor list; The circuit mode corresponding to the preset feedback circuit setting is specifically: setting the selectable circuit mode according to the feedback resistance mode of the switching power supply; In step S4, The comprehensive usage rate is an average value of the usage frequency of each feedback resistor group in the circuit mode.

2. A method for selecting a feedback resistor for a switching power supply as claimed in claim 1, It is characterized in that In step S2: The target calculation parameters include output voltage, output voltage error coefficient, and feedback voltage; The calculation mode includes a single-selection mode and a global mode. The single-selection mode is to select any one of the circuit modes for calculation, and the global mode is to calculate each of the circuit modes.

3. A method for selecting a feedback resistor for a switching power supply as claimed in claim 2, It is characterized in that The step S3 comprises: S31, selecting the corresponding circuit mode according to the calculation mode; S32, reading each resistor in the resistor list as a first feedback resistor according to a preset reading order, and substituting the target calculation parameter into a corresponding mode calculation formula to obtain a calculation range value; S33, traversing the resistance list to obtain target resistance information that meets the calculation range value; The target resistance information is independent resistance information or series resistance group information.

4. A method for selecting a feedback resistor for a switching power supply as claimed in claim 3, It is characterized in that The step S4 comprises: S41, substituting the resistance information of the first feedback resistor and the target resistance information into a preset calculation rule to calculate the comprehensive utilization rate of the feedback resistor group; S42: According to a preset sorting rule, the comprehensive usage rate is counted to obtain a comprehensive recommendation list and output it.

5. A method for selecting a feedback resistor for a switching power supply as claimed in claim 4, It is characterized in that The step S42 is specifically as follows: When the calculation mode is a single-selection mode, the comprehensive utilization rate of each feedback resistor group in the currently selected circuit mode is obtained, and a comprehensive recommendation list is obtained and output according to a preset sorting rule; When the calculation mode is a global mode, the comprehensive utilization rate of each feedback resistor group in each circuit mode is obtained, and a comprehensive recommendation list is obtained and output according to a preset sorting rule.

6. A method for selecting a feedback resistor for a switching power supply as claimed in claim 5, It is characterized in that The preset sorting rules are: A. sorting the obtained comprehensive utilization rates for the first time in descending order; B. When there are the same comprehensive utilization rates, the corresponding variances are calculated, and the same comprehensive utilization rates are ranked according to the size of the variances; C. When the same comprehensive utilization rate and the same variance exist, the resistance value of the resistor with the lowest frequency of use in the corresponding feedback resistor group is obtained as the judgment resistance value, and the same comprehensive utilization rates are ranked according to the size of the judgment resistance value.

7. A method for selecting a feedback resistor for a switching power supply as claimed in claim 3, Features: The circuit mode includes a first mode, a second mode, and a third mode; The first mode is that the feedback resistor group includes a pull-up resistor and a pull-down resistor; The second mode is that the feedback resistor group includes two pull-up resistors and one pull-down resistor; The third mode is that the feedback resistor group includes one pull-up resistor and two pull-down resistors.

8. A method for selecting a feedback resistor for a switching power supply as claimed in claim 7, Features: In the first mode, a pull-up resistor or a pull-down resistor is selected as the first feedback resistor; In the second mode, a pull-down resistor is selected as the first feedback resistor; In the third mode, a pull-up resistor is selected as the first feedback resistor.

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