A control circuit, a control method, and a switching power supply of a switching power supply

Abstract

The present invention discloses a control circuit, a control method and a switching power supply for a switching power supply. A ramp voltage signal associated with an input voltage and / or an output voltage is constructed according to the topological structure of the switching power supply, and then it is operated with an inductor current signal sampled during a conduction time period or a turn-off time period, whereby the inductor current information within one switching period can be constructed and obtained; and according to the switching time of the main switching transistor, it is selected whether to use the constructed inductor current information or the sampled inductor current information to control the main switching transistor. This application is applicable to a switching power supply adopting a dual inductor current control mode. By selecting the acquisition mode of the inductor current information according to the switching time of the main switching transistor, it is not limited by the influence of the switching time of the main switching transistor, and the switching power supply can broaden the usage range of the input voltage or the output voltage, and has a wide application range.

Description

Technical Field

[0001] The present invention relates to the field of switching power supplies, and more particularly, to a control circuit, a control method and a switching power supply of a switching power supply. Background Art

[0002] In the use of a switching power supply, it is usually necessary to provide a stable output signal to a load. The prior art generally controls the magnitude of the output signal by controlling the on / off of a main switching transistor in the switching power supply. The traditional dual-current control method controls the turn-off of the main switching transistor by comparing the error between the sampled inductor current signal in the switching power supply and a first reference signal, and controls the turn-on of the main switching transistor by comparing the error between the sampled inductor current signal and a second reference signal, thereby controlling the output signal to be an expected required value.

[0003] However, in the above control scheme, if the switching time of the main switching transistor, such as the turn-on time or the turn-off time, is relatively short, and due to the influence of the noise of the main switching transistor itself, a certain blanking time needs to be set after the main switching transistor is turned on or off, and then sampling is performed. In this way, the sampled inductor current information will be inaccurate. Therefore, the adjustment width of the input signal or the output signal of the switching power supply is limited, which affects the application range of the switching power supply. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a control circuit, a control method and a switching power supply of a switching power supply, so as to solve the technical problem that the adjustment width of the input signal or the output signal in the prior art is limited.

[0005] The technical solution of the present invention is to provide a control circuit for a switching power supply. The switching power supply includes a main switching transistor and an inductor connected to each other, and comprises: an inductor current sampling circuit for sampling the current information of the inductor to obtain a first inductor current sampling signal during the conduction period of the main switching transistor and a second inductor current sampling signal during the off period of the main switching transistor; a current signal selection circuit for receiving the first inductor current sampling signal and, within the off time of the main switching transistor, obtaining a second inductor current detection signal based on the first inductor current sampling signal and the output voltage of the power stage circuit; and for receiving the second inductor current sampling signal and, within the conduction time of the main switching transistor, obtaining a first inductor current detection signal through an operation of the second inductor current sampling signal and the input voltage of the power stage circuit or the input voltage and the output voltage; the current signal selection circuit determines to output either the first inductor current sampling signal or the first inductor current detection signal as an output signal to the subsequent circuit according to the comparison result between the conduction time of the main switching transistor and a preset first threshold time, and the current signal selection circuit determines to output either the second inductor current sampling signal or the second inductor current detection signal as an output signal to the subsequent circuit according to the comparison result between the off time of the main switching transistor and a preset second threshold time.

[0006] Preferably, the current signal selection circuit includes a first inductor current reconstruction circuit, a second inductor current reconstruction circuit and a switching time detection circuit. The first inductor current reconstruction circuit receives the second inductor current sampling signal and constructs a first ramp current signal proportional to an operation of the input voltage of the power stage circuit or the input voltage and the output voltage. The first inductor current detection signal is obtained after an operation of the second inductor current sampling signal and the first ramp current signal; the second inductor current reconstruction circuit receives the first inductor current sampling signal and constructs a second ramp current signal proportional to the output voltage of the power stage circuit. The second inductor current detection signal is obtained after an operation of the first inductor current sampling signal and the second ramp current signal. The switching time detection circuit detects the switching time of the main switching transistor and receives the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal and the second inductor current detection signal to select the output signal according to the switching time.

[0007] Preferably, the first inductor current reconstruction circuit includes an up-ramp current reconstruction circuit and a superposition circuit. The up-ramp current construction circuit constructs the first ramp current signal that is directly proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the power stage circuit topology of the switching power supply. The superposition circuit receives the second inductor current sampling signal and the first ramp current signal, and performs superposition processing to obtain the first inductor current detection signal.

[0008] Preferably, the up-ramp current construction circuit includes a first current source, a first charging capacitor, and a first switch connected in parallel with the first charging capacitor. The first current source is used to charge the first charging capacitor. The voltage signal across the first charging capacitor is the first ramp voltage signal representing the first ramp current signal. Among them, the magnitude of the first current source is set to be directly proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the topology of the power stage circuit. The switching state of the first switch is opposite to the switching state of the main switch tube.

[0009] Preferably, during the conduction period of the main switch tube, the first charging capacitor is charged by the first current source until the end of the conduction time; during the off period of the main switch tube, the first charging capacitor is discharged to zero.

[0010] Preferably, the second inductor current reconstruction circuit includes a down-ramp current reconstruction circuit and a subtraction circuit. The down-ramp current reconstruction circuit constructs the second ramp current signal that is directly proportional to the output voltage of the power stage circuit based on the power stage circuit topology of the switching power supply; the subtraction circuit receives the first inductor current sampling signal and the second ramp current signal, and performs subtraction processing to obtain the second inductor current detection signal.

[0011] Preferably, the down-ramp current reconstruction circuit includes a second current source, a second charging capacitor, and a second switch connected in parallel with the second charging capacitor. The second current source is used to charge the second charging capacitor. The voltage signal across the second charging capacitor is the second ramp voltage signal representing the second ramp current signal. Among them, the magnitude of the current source is set to be directly proportional to the output voltage of the power stage circuit. The switching state of the second switch is the same as the switching state of the main switch tube.

[0012] Preferably, during the off time of the main switch tube, the second current source charges the second charging capacitor until the end of the off time. During the on time of the main switch tube, the second charging capacitor is discharged to zero.

[0013] Preferably, the switching time detection circuit includes a switching time acquisition circuit, a comparison circuit, and a selection circuit. The switching time acquisition circuit receives the switching control signal of the main switching transistor to obtain the on-time and off-time of the main switching transistor according to the switching control signal. The comparison circuit receives the on-time and a preset first threshold time for comparison to obtain a first comparison signal, and receives the off-time and a preset second threshold time for comparison to obtain a second comparison signal. The selection circuit receives the first comparison signal and the second comparison signal, and also receives the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal, and the second inductor current detection signal. The selection circuit outputs one of the first inductor current sampling signal and the first inductor current detection signal according to the first comparison signal, and outputs one of the second inductor current sampling signal and the second inductor current detection signal according to the second comparison signal.

[0014] In a second aspect, a control circuit for a switching power supply is provided. The switching power supply includes a main switching transistor and an inductor connected to each other, and includes: an inductor current sampling circuit for sampling the current information of the inductor to obtain a first inductor current sampling signal of the main switching transistor during the on-time and a second inductor current sampling signal during the off-time; a current signal selection circuit for receiving the first inductor current sampling signal and the second inductor current sampling signal, and detecting the switching time of the main switching transistor. When it is detected that the on-time of the main switching transistor is less than the first threshold time, during the on-time of the main switching transistor, a first inductor current detection signal is obtained according to the second inductor current sampling signal and the input voltage of the power stage circuit in the switching power supply or the input voltage and the output voltage, and the first inductor current detection signal and the second inductor current sampling signal are output as output signals. When it is detected that the off-time of the main switching transistor is less than the second threshold time, during the off-time of the main switching transistor, a second inductor current detection signal is obtained according to the first inductor current sampling signal and the output voltage of the power stage circuit of the switching power supply, and the second inductor current detection signal and the first inductor current sampling signal are output as output signals. When it is detected that the on-time of the main switching transistor is greater than the first threshold time and the off-time is greater than the second threshold time, the first inductor current sampling signal and the second inductor current sampling signal are output.

[0015] Preferably, the current signal selection circuit includes a switching time detection circuit, a first inductor current reconstruction circuit, a second inductor current reconstruction circuit, and a selection circuit. The switching time detection circuit detects the switching time of the main switching transistor and receives the first inductor current sampling signal and the second inductor current sampling signal, and selects whether to output the first inductor current sampling signal or the second inductor current sampling signal to the subsequent circuit according to the switching time. When the first inductor current reconstruction circuit receives the second inductor current sampling signal output by the switching time detection circuit, it constructs a first ramp voltage signal based on the input voltage of the power stage circuit or the operation of the input voltage and the output voltage. After the second inductor current sampling signal and the first ramp voltage signal are operated, the first inductor current detection signal is obtained. When the second inductor current reconstruction circuit receives the first inductor current sampling signal output by the switching time detection circuit, it constructs a second ramp voltage signal according to the operation of the output voltage of the power stage circuit. After the first inductor current sampling signal and the second ramp voltage signal are operated, the second inductor current detection signal is obtained. The selection circuit outputs the first inductor current detection signal and the second inductor current sampling signal according to the switching time detection result of the switching time detection circuit, or selects to output the second inductor current detection signal and the first inductor current sampling signal, or outputs the first inductor current sampling signal and the second inductor current sampling signal.

[0016] Preferably, the first inductor current reconstruction circuit includes an up-ramp current reconstruction circuit and a superposition circuit. The up-ramp current construction circuit constructs a first ramp current signal that is proportional to the input voltage of the power stage circuit of the switching power supply or the difference between the input voltage and the output voltage based on the topology of the power stage circuit. The superposition circuit receives the second inductor current sampling signal and the first ramp current signal and performs superposition processing to obtain the first inductor current detection signal.

[0017] Preferably, the up-ramp current construction circuit includes a first current source, a first charging capacitor, and a first switch connected in parallel with the first charging capacitor. The first current source is used to charge the first charging capacitor. The voltage signal across the first charging capacitor is a first ramp voltage signal representing the first ramp current signal. Among them, the magnitude of the first current source is set to be proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the topology of the power stage circuit, and the switching state of the first switch is opposite to the switching state of the main switching transistor.

[0018] Preferably, during the conduction period of the main switching transistor, the first charging capacitor is charged by the first current source until the end of the conduction time; during the off period of the main switching transistor, the first charging capacitor is discharged to zero.

[0019] Preferably, the second inductor current reconstruction circuit includes a falling current reconstruction circuit and a subtraction circuit. The falling current reconstruction circuit constructs the second ramp current signal that is proportional to the output voltage of the power stage circuit based on the power stage circuit topology of the switching power supply; the subtraction circuit receives the first inductor current sampling signal and the second ramp current signal, and performs subtraction processing to obtain the second inductor current detection signal.

[0020] Preferably, the falling current reconstruction circuit includes a second current source, a second charging capacitor, and a second switch connected in parallel with the second charging capacitor. The second current source is used to charge the second charging capacitor, and the voltage signal across the second charging capacitor is the second ramp voltage signal representing the second ramp current signal. Among them, the magnitude of the current source is set to be proportional to the output voltage of the power stage circuit, and the switching state of the second switch is the same as the switching state of the main switching transistor.

[0021] Preferably, during the off time of the main switching transistor, the second current source charges the second charging capacitor, and during the on time of the main switching transistor, the second charging capacitor is discharged to zero.

[0022] Preferably, the switching time detection circuit includes a switching time acquisition circuit, a comparison circuit, and a switching circuit. The switching time acquisition circuit receives the switching control signal of the main switching transistor to obtain the on time and off time of the main switching transistor according to the switching control signal; the comparison circuit receives the on time and a preset first threshold time, and performs comparison to obtain a first comparison signal; receives the off time and a preset second threshold time, and performs comparison to obtain a second comparison signal; the switching circuit receives the first comparison signal, the second comparison signal, and also receives the first inductor current sampling signal and the second inductor current sampling signal. The switching circuit decides whether to output the first inductor current sampling signal to the subsequent circuit according to the first comparison signal; decides whether to output the second inductor current sampling signal to the subsequent circuit according to the second comparison signal.

[0023] In a third aspect, a control method for a switching power supply is provided. The switching power supply includes a main switching transistor and an inductor connected to each other, and includes the steps:

[0024] S1: Sample the current information of the inductor to obtain a first inductor current sampling signal of the main switch tube during the on-time and a second inductor current sampling signal during the off-time;

[0025] S2: Receive the first inductor current sampling signal, and during the off-time of the main switch tube, obtain a second inductor current detection signal according to the first inductor current sampling signal and the output voltage of the power stage circuit;

[0026] And receive the second inductor current sampling signal, and during the on-time of the main switch tube, obtain a first inductor current detection signal according to the second inductor current sampling signal and the input voltage of the power stage circuit or the operation of the input voltage and the output voltage;

[0027] S3: Determine to output one of the first inductor current sampling signal and the first inductor current detection signal as an output signal to the subsequent stage circuit according to the comparison result between the on-time of the main switch tube and a preset first threshold time,

[0028] And, the current signal selection circuit determines to output one of the second inductor current sampling signal and the second inductor current detection signal as an output signal to the subsequent stage circuit according to the comparison result between the off-time of the main switch tube and a preset second threshold time.

[0029] Preferably, receive the second inductor current sampling signal, and construct a first ramp current signal proportional to the operation of the input voltage of the power stage circuit or the input voltage and the output voltage, and obtain the first inductor current detection signal after operating the second inductor current sampling signal and the first ramp current signal; receive the first inductor current sampling signal, and construct a second ramp current signal proportional to the output voltage of the power stage circuit, and obtain the second inductor current detection signal after operating the first inductor current sampling signal and the second ramp current signal,

[0030] Detect the switching time of the main switch tube, and receive the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal, and the second inductor current detection signal to select the output signal according to the switching time.

[0031] In a fourth aspect, a control method for a switching power supply is provided, where the switching power supply includes a main switch tube and an inductor connected to each other,

[0032] S1: Sample the current information of the inductor to obtain a first inductor current sampling signal of the main switch tube during the on-time and a second inductor current sampling signal during the off-time;

[0033] S2: Receive the first inductor current sampling signal and the second inductor current sampling signal, and detect the switching time of the main switch transistor.

[0034] When it is detected that the conduction time of the main switch transistor is less than a first threshold time, within the conduction time of the main switch transistor, perform an operation based on the second inductor current sampling signal and the input voltage of the power stage circuit or the operation of the input voltage and the output voltage to obtain a first inductor current detection signal, and output the first inductor current detection signal and the second inductor current sampling signal as output signals.

[0035] When it is detected that the turn-off time of the main switch transistor is less than a second threshold time, within the turn-off time of the main switch transistor, obtain a second inductor current detection signal based on the first inductor current sampling signal and the output voltage of the power stage circuit, and output the second inductor current detection signal and the first inductor current sampling signal as output signals.

[0036] When it is detected that the conduction time of the main switch transistor is greater than the first threshold time and the turn-off time is greater than the second threshold time, output the first inductor current sampling signal and the second inductor current sampling signal.

[0037] Preferably, detect the switching time of the main switch transistor, and receive the first inductor current sampling signal and the second inductor current sampling signal to select whether to output the first inductor current sampling signal or the second inductor current sampling signal to the subsequent circuit according to the switching time.

[0038] When receiving the second inductor current sampling signal, construct a first ramp voltage signal that is proportional to the operation of the input voltage of the power stage circuit or the input voltage and the output voltage, and perform an operation on the second inductor current sampling signal and the first ramp voltage signal to obtain the first inductor current detection signal.

[0039] When receiving the first inductor current sampling signal, construct a second ramp voltage signal that is proportional to the output voltage of the power stage circuit, and perform an operation on the first inductor current sampling signal and the second ramp voltage signal to obtain the second inductor current detection signal.

[0040] Output the first inductor current detection signal and the first inductor current sampling signal according to the switching time detection result of the switching time detection circuit of the switch time, or select to output the second inductor current detection signal and the second inductor current sampling signal, or output the first inductor current sampling signal and the second inductor current sampling signal.

[0041] In a fifth aspect, a switching power supply is provided, including the above control circuit, and further including a comparison circuit and a logic and drive circuit.

[0042] The comparison circuit includes a first comparator and a second comparator. The first comparator receives the first inductor current detection signal or the first inductor current sampling signal transmitted by the control circuit to compare with a first reference voltage signal to obtain a first comparison signal;

[0043] The second comparator receives the second inductor current detection signal or the second inductor current sampling signal transmitted by the control circuit to compare with a second reference voltage signal to obtain a second comparison signal;

[0044] The logic and drive circuit receives the first comparison signal and the second comparison signal, and accordingly generates a switch control signal for controlling the switching state of the main switch tube in the switching power supply.

[0045] By using the control circuit, control method and switching power supply of the present invention, a ramp voltage signal associated with the input voltage and / or output voltage is constructed according to the topology of the switching power supply, and then added or subtracted from the inductor current signal sampled during the on-time period or off-time period, whereby the inductor current information within one switching period can be constructed; and according to the switching time of the main switch tube, it is selected whether to use the constructed inductor current information or the sampled inductor current information to control the main switch tube. This application is applicable to a switching power supply with a dual inductor current control mode. By selecting the acquisition method of the inductor current information according to the switching time of the main switch tube, it is not limited by the switching time of the main switch tube, and the switching power supply can broaden the usage range of the input voltage or output voltage, and has a wide application range. Brief Description of the Drawings

[0046] Figure 1 It is a circuit block diagram of the control circuit of the switching power supply of the present invention;

[0047] Figure 2 It is a circuit block diagram of the first implementation manner of the control circuit in the present invention;

[0048] Figure 2-1 It is Figure 2 a kind of implementation manner of the switching time detection circuit in

[0049] Figure 2-2 It is Figure 2 a kind of implementation manner of the uphill current construction circuit in

[0050] Figure 3 It is a circuit block diagram of the second implementation manner of the control circuit in the present invention;

[0051] Figure 3-1 It is Figure 3 a kind of implementation manner of the switching time detection circuit in Detailed Embodiments

[0052] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any alternatives, modifications, equivalent methods, and solutions within the spirit and scope of the present invention.

[0053] In order to enable the public to have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention. However, those skilled in the art can fully understand the present invention without these detailed descriptions.

[0054] The present invention will be described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. It should be noted that the accompanying drawings are all in a relatively simplified form and use non-precise scales, only for the purpose of facilitating and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0055] As Figure 1 shown in the circuit block diagram of the control circuit of the switching power supply according to the present invention, in this embodiment, the power stage circuit of the switching power supply takes the buck topology as an example. This topology includes a main switching transistor Q1, an inductor L connected to the main switching transistor Q1, a synchronous rectifier transistor Q2, and an output capacitor Co. The power stage circuit receives an input signal Vin, and after the switching conversion of the main switching transistor Q1, it outputs a DC output signal Vout to supply the load. The voltage across the output capacitor Co is denoted as the output voltage signal Vo.

[0056] As Figure 1 shown, the control circuit of the embodiment of the present invention includes an inductor current sampling circuit 1, a current signal selection circuit 2, a comparison circuit 3, and a logic and drive circuit 4. Here, the control circuit also includes some other circuit structures for realizing input and output functions, which are not shown in Figure 1 because they are not directly related to the technical solution of the present invention.

[0057] Referring to Figure 1 , the inductor current sampling circuit 1 samples the current information of the inductor to obtain a first inductor current sampling signal I of the main switching transistor during the on-time PK1 ( Figure 1 characterized by the corresponding first inductor voltage sampling signal V in IPK1 ) and a second inductor current sampling signal I of the main switching transistor during the off-time Bot1 ( Figure 1 characterized by the corresponding first inductor voltage sampling signal V in IBot1 ).

[0058] Combined with Figure 2 , in this embodiment, the current signal selection circuit 2 includes a first inductor current reconstruction circuit 2-1, a second inductor current reconstruction circuit 2-2, and a switching time detection circuit 2-3:

[0059] The first inductor current reconstruction circuit 2-1 receives the second inductor current sampling signal I Bot1 , and constructs a first ramp current signal I COMP1 ( Figure 2 characterized by a corresponding first ramp voltage signal V COMP1 ) that is proportional to the input voltage of the power stage circuit or the operation of the input voltage and the output voltage. After the operation of the second inductor current sampling signal and the first ramp current signal, a first inductor current detection signal I PK2 ( Figure 2 characterized by a corresponding first inductor voltage detection signal V IPK2 ) is obtained.

[0060] Specifically, the first inductor current reconstruction circuit includes an up-ramp current reconstruction circuit 2-1-1 and a superposition circuit 2-1-2. The up-ramp current construction circuit 2-1-1 constructs the first ramp current signal I COMP1 that is proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the topology of the power stage circuit of the switching power supply; The superposition circuit 2-1-2 receives the second inductor current sampling signal I Bot1 and the first ramp current signal I COMP1 , and performs superposition processing to obtain a first inductor current detection signal I PK2 ( Figure 2 characterized by a corresponding first inductor voltage detection signal V IPK2 ). The superposition circuit can be an adder.

[0061] Combined with Figure 2-2 , the up-ramp current construction circuit 2-1-1 includes a first current source I1, a first charging capacitor C1, and a first switch S1 connected in parallel with the first charging capacitor. The first current source is used to charge the first charging capacitor, and the voltage signal across the two ends of the first charging capacitor is the first ramp voltage signal V COMP1 that characterizes the first ramp current signal. Among them, the magnitude of the first current source is set to be proportional to the difference between the input voltage of the power converter or the input voltage and the output voltage based on the topology of the power stage circuit. The switching state of the first switch is opposite to the switching state of the main switch tube. During the conduction period of the main switch tube, the first charging capacitor is charged by the first current source until the end of the conduction time; during the off period of the main switch tube, the first charging capacitor is discharged to zero.

[0062] It can be inferred from constructing a circuit based on the above-mentioned rising current that for the buck power circuit structure, the current waveform of the inductor L is a triangular wave. During the conduction period Ton of the main switch, the current of the main switch Q1 rises, and during the off period Toff, the current of the synchronous switch Q2 decreases. During the conduction period, the inductor current is equal to the current of the main switch Q1 and rises linearly. According to the working volt-second product principle of the buck circuit, the magnitude of the rising inductor current △I is the integral of (Vin - Vo) / L with respect to the conduction time. In this embodiment, the current I of the current source is set to I ∝ K*(Vin - Vo). When the main switch Q1 is conducting, the first switch S is turned off, and the current source I charges the charging capacitor, and the first ramp voltage signal is accordingly: V COMP1 ∝ K*(Vin - Vo). In an ideal case, the proportionality coefficient K = 1 / L. In an actual circuit, the inductor L will have a slight variation, and generally, an average value within a suitable inductance value range is selected, which has a small impact on the slope of the first ramp voltage signal. Therefore, the first ramp current signal V COMP1 constructed by the above-mentioned rising current constructing circuit can characterize the magnitude of the rising inductor current △I.

[0063] In the continuous conduction mode, during the off time of the main switch, the information of the inductor current can be obtained through sampling. When reaching the end of the off time, the magnitude of the inductor current I Bot1 at the moment when the off time arrives can be obtained. Then, during the conduction period, the first ramp current signal I COMP1 (the corresponding voltage is represented as V COMP1 ) is constructed by the ramp current constructing circuit of the embodiment of the present invention. Then, at the end of the conduction time, the first ramp current signal I COMP1 is superimposed on the magnitude of the inductor current I Bot1 to obtain the magnitude situation of the inductor current during the conduction period of the main switch. In this way, the inductor current information within the entire switching period can be obtained through the above method.

[0064] Continuing to refer to Figure 2 , the second inductor current reconstruction circuit 2-2 receives the first inductor current sampling signal I PK1 , and constructs a second ramp current signal I COMP2 ( Figure 2 is characterized by the corresponding second ramp voltage signal V COMP2 ) based on the output voltage of the power stage circuit. After the first inductor current sampling signal and the second ramp current signal are operated, a second inductor current detection signal I Bot2 ( Figure 2 is characterized by the corresponding second inductor voltage detection signal V IBot2Characterization). Specifically, the second inductor current reconstruction circuit includes a downhill current reconstruction circuit 2-2-1 and a subtraction circuit 2-2-2.

[0065] The downhill current reconstruction circuit 2-2-1 constructs the second ramp current signal I that is directly proportional to the output voltage of the switching power supply based on the power stage circuit topology of the switching power supply. COMP2 ( Figure 2 characterized by the corresponding second ramp voltage signal V in COMP2 ; The subtraction circuit receives the first inductor current sampling signal and the second ramp current signal, and performs subtraction processing to obtain the second inductor current detection signal I. Bot2 ( Figure 2 characterized by the corresponding second inductor voltage detection signal V in IBot2 ). Similarly, in this embodiment, the downhill current reconstruction circuit includes a second current source, a second charging capacitor, and a second switch connected in parallel with the second charging capacitor. The second current source is used to charge the second charging capacitor. The voltage signal across the second charging capacitor is the second ramp voltage signal characterizing the second ramp current signal. Among them, the magnitude of the current source is set to be directly proportional to the output voltage of the power stage circuit, and the switching state of the second switch is the same as that of the main switch tube. During the off-time of the main switch tube, the second current source charges the second charging capacitor until the off-time ends. During the on-time of the main switch tube, the second charging capacitor discharges to zero.

[0066] The working principle of the downhill current construction circuit is similar to that of the uphill current construction circuit. The difference is that sampling is performed during the conduction period to obtain the inductor current signal I at the moment when the conduction time arrives. PK1 , and then during the off-time period, for the Buck topology, the inductor current is directly proportional to the output voltage. The second ramp current signal I that is directly proportional to the output voltage is constructed through the ramp current construction circuit of the embodiment of the present invention. COMP2 (the corresponding voltage is denoted as V COMP2 ), and the second ramp current signal I COMP2 can characterize the change magnitude of the inductor current during the off-time. Then, at the end of the off-time, subtracting the second ramp current signal I Bot2 from the inductor current magnitude I COMP2 can obtain the magnitude of the inductor current during the off-time period of the main switch tube. In this way, by combining the sampling method during the conduction time and the construction method during the off-time, the inductor current information during the entire switching cycle can be accurately obtained.

[0067] The switching time detection circuit 2-3 detects the switching time of the main switching transistor and receives the first inductor current sampling signal, the second inductor current sampling signal I Bot1 , the first inductor current detection signal I PK1 , and the second inductor current detection signal I Bot2 , so as to select the output signal I according to the switching time PK2 .

[0068] Specifically, the switching time detection circuit includes a switching time acquisition circuit 2-3-1, a comparison circuit 2-3-2 and a selection circuit 2-3-3. The switching time acquisition circuit 2-3-1 receives the switching control signal V of the main switching transistor Q , so as to obtain the on-time Ton and off-time Toff of the main switching transistor according to the switching control signal; the comparison circuit 2-3-2 receives the on-time Ton and a preset first threshold time Ton_min, and compares them to obtain a first comparison signal Vc1; receives the off-time Toff and a preset second threshold time Toff_min, and compares them to obtain a second comparison signal Vc2.

[0069] The selection circuit 2-3-3 receives the first comparison signal and the second comparison signal, and also receives the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal and the second inductor current detection signal. The selection circuit outputs one of the first inductor current sampling signal and the first inductor current detection signal according to the first comparison signal; outputs one of the second inductor current sampling signal and the second inductor current detection signal according to the second comparison signal.

[0070] In this embodiment, when the on-time Ton is less than or equal to the preset first threshold time Ton_min, the first inductor current detection signal is selected to be output, otherwise, the first inductor current sampling signal is selected to be output; when the off-time Toff is less than or equal to the preset second threshold time Toff_min, the second inductor current detection signal is selected to be output, otherwise, the second inductor current sampling signal is selected to be output. With such a setting, during the operation of the switching power supply, when the on-time or off-time is relatively short, the sampled information may be inaccurate. By using the constructed inductor current signal as the output signal and transmitting it to the subsequent comparison circuit, accurate inductor current information can be obtained, and the control is more accurate. When the on-time or off-time is relatively long, the subsequent circuit is controlled by the sampled inductor current information. It should be noted here that due to the frequency design of the switching power supply itself, there will be no situation where both the on-time and off-time are less than the preset time, that is, there will be no situation where the inductor current information is constructed during both the on-time stage and the off-time stage.

[0071] Those skilled in the art can understand that the switching time acquisition circuit, comparison circuit, and selection circuit in the embodiments of this solution can be implemented by switching transistors, comparators, and devices with the same functions. The circuit structure is not specifically limited herein.

[0072] In the switching power supply, the comparison circuit 3 includes a first comparator CMP1 and a second comparator CMP2. The first comparator receives the first inductor current detection signal or the first inductor current sampling signal transmitted by the control circuit to compare with the first reference voltage signal Vref1 to obtain a first comparison signal;

[0073] The second comparator receives the second inductor current detection signal or the second inductor current sampling signal transmitted by the control circuit to compare with the second reference voltage signal Vref2 to obtain a second comparison signal;

[0074] The logic and drive circuit 4 receives the first comparison signal and the second comparison signal, and generates a switching control signal V accordingly Q for controlling the switching state of the main switching transistor in the switching power supply.

[0075] Reference Figure 3 is the circuit block diagram of the second implementation manner of the control circuit in the present invention; Figure 3-1 is Figure 3 a realization manner of the switching time detection circuit in Figure 1 Combined with PK1 ( Figure 3 in IPK1 is characterized by the corresponding first inductor voltage sampling signal V Bot1 ( Figure 3 in IBot1 is characterized by the corresponding first inductor voltage sampling signal V Figure 3 ), the inductor current sampling circuit 1 samples the current information of the inductor to obtain the first inductor current sampling signal I of the main switching transistor during the on-time

[0076] Continue to refer to Figure 3 In this embodiment, the current signal selection circuit 2 includes a switching time detection circuit 2-1, a first inductor current reconstruction circuit 2-2, a second inductor current reconstruction circuit 2-3, and a selection circuit 2-4.

[0077] Specifically, the switching time detection circuit detects the switching time of the main switching transistor and receives the first inductor current sampling signal I PK1 and the second inductor current sampling signal I Bot1, to select whether to output the first inductor current sampling signal or the second inductor current sampling signal to the subsequent circuit according to the switching time. Refer to Figure 3-1 , the switching time detection circuit includes a switching time acquisition circuit 2-1-1, a comparison circuit 2-1-2, and a switching circuit 2-1-3. The switching time acquisition circuit 2-1-1 receives the switching control signal V of the main switching transistor Q , to obtain the on-time Ton and off-time Toff of the main switching transistor according to the switching control signal;

[0078] The comparison circuit 2-1-2 receives the on-time Ton and a preset first threshold time Ton_min, and compares them to obtain a first comparison signal Vc1; receives the off-time Toff and a preset second threshold time Toff_min, and compares them to obtain a second comparison signal Vc2;

[0079] The switching circuit receives the first comparison signal, the second comparison signal, and also receives the first inductor current sampling signal I PK1 and the second inductor current sampling signal I Bot1 , the switching circuit decides whether to output the second inductor current sampling signal to the subsequent circuit according to the first comparison signal; decides whether to output the first inductor current sampling signal to the subsequent circuit according to the second comparison signal. The switching circuit here can be implemented by a switching transistor. In this embodiment, when the on-time Ton is less than or equal to the preset first threshold time Ton_min, the first inductor current sampling signal is output to the subsequent circuit. When the off-time Toff is less than or equal to the preset second threshold time Toff_min, the first inductor current sampling signal is output to the subsequent circuit.

[0080] Specifically, when the first inductor current reconstruction circuit 2-2 receives the second inductor current sampling signal (the corresponding voltage signal is denoted as V IBot1 ) output by the switching time detection circuit, a first ramp voltage signal V is constructed according to the output voltage of the power stage circuit COMP1 , and the first inductor current detection signal I is obtained after the second inductor current sampling signal and the first ramp voltage signal are operated PK1 ; Specifically, the first inductor current reconstruction circuit includes an uphill current reconstruction circuit 2-2-1 and a superposition circuit 2-2-2. The uphill current construction circuit constructs the first ramp current signal I that is proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the power stage circuit topology of the switching power supply COMP1, the superimposing circuit receives the second inductor current sampling signal and the first ramp current signal, and performs a superimposing process to obtain the first inductor current detection signal I PK2 , the superimposing circuit can be an adder.

[0081] Specifically, the rising current constructing circuit in this embodiment includes a first current source, a first charging capacitor, and a first switch connected in parallel with the first charging capacitor. The first current source is used to charge the first charging capacitor, and the voltage signal across the first charging capacitor is the first ramp voltage signal representing the first ramp current signal. Among them, the magnitude of the first current source is set to be directly proportional to the topology of the power stage circuit and the input voltage of the power converter or the difference between the input voltage and the output voltage. The switching state of the first switch is opposite to the switching state of the main switch tube. During the conduction period of the main switch tube, the first charging capacitor is charged by the first current source until the end of the conduction time; during the off period of the main switch tube, the first charging capacitor is discharged to zero.

[0082] Similarly, the working principle of the rising current constructing circuit in this embodiment is the same as that of the previous embodiment. The constructed ramp current signal can represent the information of the inductor current rising during the conduction time. By sampling the inductor current information during the off time of the main switch tube, when reaching the end of the off time, the magnitude of the inductor current I at the moment when the off time arrives can be obtained Bot1 , and then during the conduction period, a first ramp current signal I COMP1 (the corresponding voltage is represented as V COMP1 ) is constructed, and then at the end of the conduction time, the first ramp current signal I COMP1 is superimposed on the magnitude of the inductor current I Bot1 to obtain the magnitude condition of the inductor current during the conduction period of the main switch tube. In this way, the inductor current information during the entire switching period can be obtained through the above method.

[0083] Moreover, in this implementation scheme, by first detecting whether the conduction time (such as the conduction time in the previous period) is smaller than the preset conduction time. If it is less than the preset conduction time, it means that the sampling time is insufficient, and the sampled inductor current signal will be inaccurate. Therefore, in the next period, the inductor current information during a switching period can be obtained through the constructed inductor current information, with accurate control and high precision.

[0084] Specifically, when the second inductor current reconstruction circuit 2-3 receives the first inductor current sampling signal I output by the switching time detection circuit PK1 , then a second ramp voltage signal V is constructed according to the operation of the output voltage of the power stage circuit COMP2, the first inductor current sampling signal and the second ramp voltage signal are operated to obtain a second inductor current detection signal I Bot2 ; specifically, the second inductor current reconstruction circuit 2-3 includes a falling current reconstruction circuit 2-3-1 and a subtraction circuit 2-3-2. The falling current reconstruction circuit constructs the second ramp current signal that is in direct proportion to the output voltage of the switching power supply based on the power stage circuit topology of the switching power supply; the subtraction circuit receives the first inductor current sampling signal and the second ramp current signal, and performs subtraction processing to obtain the second inductor current detection signal I Bot2 (such as Figure 3 the corresponding V in IBot2 ). The subtraction circuit can be a subtractor.

[0085] Specifically, the falling current reconstruction circuit 2-3-1 includes a second current source, a second charging capacitor, and a second switch connected in parallel with the second charging capacitor. The second current source is used to charge the second charging capacitor. The voltage signal across the two ends of the second charging capacitor is the second ramp voltage signal representing the second ramp current signal. Among them, the magnitude of the current source is set to be in direct proportion to the output voltage of the power stage circuit, and the switching state of the second switch is the same as that of the main switch tube. During the off-time of the main switch tube, the second current source charges the second charging capacitor. During the on-time of the main switch tube, the second charging capacitor discharges to zero.

[0086] Similarly, the principle of the falling current reconstruction circuit in this embodiment is the same as that in the previous embodiment. Therefore, by subtracting the magnitude of the constructed ramp current from the magnitude of the inductor current at the end of the on-time, the inductor current information during the off period can be obtained. By combining it with the inductor current information sampled during the on period, accurate inductor current information within one switching period can be obtained.

[0087] Specifically, the selection circuit 2-4 includes two parts, such as Figure 3Select circuits 2-4-1 and 2-4-2. The select circuit outputs the first inductor current detection signal and the second inductor current sampling signal according to the switch time detection result of the switch time detection circuit, or alternatively, selects to output the second inductor current detection signal and the first inductor current sampling signal, or outputs the first inductor current sampling signal and the second inductor current sampling signal. Specifically, when receiving the first inductor current detection signal output by the first inductor current reconstruction circuit, it selects to output the first inductor current detection signal and the second inductor current sampling signal; when receiving the second inductor current detection signal, it selects to output the second inductor current detection signal and the first inductor current sampling signal; if neither the first inductor current detection signal nor the second inductor current detection signal is received, it selects to output the first inductor current sampling signal and the second inductor current sampling signal. It should be noted here that due to the frequency design of the switching power supply itself, there will be no situation where both the conduction time and the turn-off time are less than the preset time, that is, there will be no situation where the inductance current information is constructed in both the conduction time stage and the turn-off time stage.

[0088] In this embodiment, based on the detection of the switch time, when it is found that the conduction time or the turn-off time is very short, the inductance current information during the conduction or turn-off time is obtained through construction, and the control method is accurate and has good precision.

[0089] In a second aspect, the present invention discloses a control method for a switching power supply. The switching power supply includes a main switch tube and an inductor connected to each other, and includes the steps of:

[0090] S1: Sample the current information of the inductor to obtain a first inductor current sampling signal of the main switch tube during the conduction time and a second inductor current sampling signal during the turn-off time;

[0091] S2: Receive the first inductor current sampling signal, and during the turn-off time of the main switch tube, construct a second inductor current detection signal proportional to the output voltage of the power stage circuit according to the power topology of the switching power supply;

[0092] And receive the second inductor current sampling signal, and during the conduction time of the main switch tube, construct a first inductor current detection signal proportional to the input voltage of the power stage circuit or the operation of the input voltage and the output voltage according to the power topology of the switching power supply;

[0093] S3: Determine to output one of the first inductor current sampling signal and the first inductor current detection signal as the output signal to the subsequent circuit according to the comparison result of the conduction time of the main switch tube and a preset first threshold time.

[0094] Further, the current signal selection circuit determines to output one of the second inductor current sampling signal and the second inductor current detection signal as an output signal to the subsequent circuit according to the comparison result between the turn-off time of the main switch tube and a preset second threshold time.

[0095] It further includes receiving the second inductor current sampling signal and constructing a first ramp current signal that is proportional to the input voltage of the power stage circuit or the operation of the input voltage and the output voltage, and obtaining a first inductor current detection signal after operating the second inductor current sampling signal and the first ramp current signal;

[0096] Receiving the first inductor current sampling signal and constructing a second ramp current signal that is proportional to the output voltage of the power stage circuit, and obtaining a second inductor current detection signal after operating the first inductor current sampling signal and the second ramp current signal,

[0097] Detecting the switching time of the main switch tube, and receiving the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal, and the second inductor current detection signal to select the output signal according to the switching time.

[0098] In a third aspect, the present invention discloses a control method for a switching power supply, where the switching power supply includes a main switch tube and an inductor connected to each other, and includes the steps of:

[0099] S1: Sampling the current information of the inductor to obtain a first inductor current sampling signal of the main switch tube during the conduction time and a second inductor current sampling signal during the turn-off time;

[0100] S2: Receiving the first inductor current sampling signal and the second inductor current sampling signal, and detecting the switching time of the main switch tube,

[0101] When it is detected that the conduction time of the main switch tube is less than the first threshold time, a first inductor current detection signal proportional to the operation of the input voltage of the power stage circuit or the input voltage and the output voltage is constructed according to the power topology of the switching power supply during the conduction time of the main switch tube, and the first inductor current detection signal and the second inductor current sampling signal are output as output signals,

[0102] When it is detected that the turn-off time of the main switch tube is less than the second threshold time, a second inductor current detection signal proportional to the output voltage of the power stage circuit is constructed according to the power topology of the switching power supply during the turn-off time of the main switch tube, and the second inductor current detection signal and the first inductor current sampling signal are output as output signals,

[0103] When it is detected that the conduction time of the main switching tube is greater than the first threshold time and the turn-off time is greater than the second threshold time, the first inductor current sampling signal and the second inductor current sampling signal are output.

[0104] It further includes the steps of detecting the switching time of the main switching tube, and receiving the first inductor current sampling signal and the second inductor current sampling signal, so as to select whether to output the first inductor current sampling signal or the second inductor current sampling signal to the subsequent circuit according to the switching time.

[0105] When the first inductor current reconstruction circuit receives the second inductor current sampling signal output by the switching time detection circuit, a first ramp voltage signal is constructed according to the output voltage of the power stage circuit, and the first inductor current detection signal is obtained after the operation of the second inductor current sampling signal and the first ramp voltage signal.

[0106] When the second inductor current reconstruction circuit receives the first inductor current sampling signal output by the switching time detection circuit, a second ramp voltage signal is constructed according to the input voltage of the power stage circuit or the operation of the input voltage and the output voltage, and the second inductor current detection signal is obtained after the operation of the first inductor current sampling signal and the second ramp voltage signal.

[0107] The first inductor current detection signal and the first inductor current sampling signal are output according to the switching time detection result of the switching time detection circuit, or the second inductor current detection signal and the second inductor current sampling signal are selected to be output, or the first inductor current sampling signal and the second inductor current sampling signal are output.

[0108] The above-described embodiments do not constitute a limitation on the protection scope of the technical solution. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the above embodiments shall be included in the protection scope of the technical solution.

Claims

1. A control circuit for a switching power supply, the switching power supply including a main switching transistor and an inductor connected to each other, characterized in that, it includes: An inductor current sampling circuit that samples the current information of the inductor to obtain a first inductor current sampling signal during the conduction period of the main switching transistor and a second inductor current sampling signal during the off period; A current signal selection circuit that receives the first inductor current sampling signal and, within the off time of the main switching transistor, obtains a second inductor current detection signal based on the first inductor current sampling signal and the output voltage of the power stage circuit; And it receives the second inductor current sampling signal and, within the on time of the main switching transistor, obtains a first inductor current detection signal through the operation of the second inductor current sampling signal with the input voltage of the power stage circuit or the input voltage and the output voltage; The current signal selection circuit determines to output one of the first inductor current sampling signal and the first inductor current detection signal as an output signal to the subsequent circuit according to the comparison result of the on time of the main switching transistor with a preset first threshold time, and, the current signal selection circuit determines to output one of the second inductor current sampling signal and the second inductor current detection signal as an output signal to the subsequent circuit according to the comparison result of the off time of the main switching transistor with a preset second threshold time.

2. The control circuit according to claim 1, characterized in that, the current signal selection circuit includes a first inductor current reconstruction circuit, a second inductor current reconstruction circuit and a switching time detection circuit, the first inductor current reconstruction circuit receives the second inductor current sampling signal and constructs a first ramp current signal proportional to the operation of the input voltage of the power stage circuit or the input voltage and the output voltage, and the first inductor current detection signal is obtained after the operation of the second inductor current sampling signal and the first ramp current signal; the second inductor current reconstruction circuit receives the first inductor current sampling signal and constructs a second ramp current signal proportional to the output voltage of the power stage circuit, and the second inductor current detection signal is obtained after the operation of the first inductor current sampling signal and the second ramp current signal, the switching time detection circuit detects the switching time of the main switching transistor and receives the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal and the second inductor current detection signal to select the output signal according to the switching time.

3. The control circuit according to claim 2, characterized in that, the first inductor current reconstruction circuit includes an uphill current reconstruction circuit and a superposition circuit, the uphill current reconstruction circuit constructs the first ramp current signal that is directly proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the power stage circuit topology of the switching power supply, the superposition circuit receives the second inductor current sampling signal and the first ramp current signal and performs superposition processing to obtain the first inductor current detection signal.

4. The control circuit according to claim 3, wherein, the uphill current reconstruction circuit includes a first current source, a first charging capacitor, and a first switch connected in parallel with the first charging capacitor, the first current source is used to charge the first charging capacitor, and the voltage signal across the first charging capacitor is a first ramp voltage signal representing the first ramp current signal, wherein, the magnitude of the first current source is set to be in direct proportion to the topology of the power stage circuit and the input voltage of the power stage circuit or the difference between the input voltage and the output voltage, and the switching state of the first switch is opposite to the switching state of the main switch tube.

5. The control circuit according to claim 4, wherein, during the conduction period of the main switch tube, the first charging capacitor is charged by the first current source until the end of the conduction time; during the off period of the main switch tube, the first charging capacitor is discharged to zero.

6. The control circuit according to claim 2, wherein, the second inductor current reconstruction circuit includes a downhill current reconstruction circuit and a subtraction circuit, the downhill current reconstruction circuit constructs the second ramp current signal that is in direct proportion to the output voltage of the power stage circuit based on the topology of the power stage circuit of the switching power supply; the subtraction circuit receives the first inductor current sampling signal and the second ramp current signal, and performs subtraction processing to obtain the second inductor current detection signal.

7. The control circuit according to claim 6, wherein, the downhill current reconstruction circuit includes a second current source, a second charging capacitor, and a second switch connected in parallel with the second charging capacitor, the second current source is used to charge the second charging capacitor, and the voltage signal across the second charging capacitor is a second ramp voltage signal representing the second ramp current signal, wherein, the magnitude of the current source is set to be in direct proportion to the output voltage of the power stage circuit, and the switching state of the second switch is the same as the switching state of the main switch tube.

8. The control circuit according to claim 7, wherein, during the off time of the main switch tube, the second current source charges the second charging capacitor until the end of the off time, and during the on time of the main switch tube, the second charging capacitor is discharged to zero.

9. The control circuit according to any one of claims 2-8, wherein, the switching time detection circuit includes a switching time acquisition circuit, a comparison circuit, and a selection circuit, the switching time acquisition circuit receives the switching control signal of the main switch tube to obtain the on time and off time of the main switch tube according to the switching control signal; the comparison circuit receives the on time and a preset first threshold time, and performs comparison to obtain a first comparison signal; receives the off time and a preset second threshold time, and performs comparison to obtain a second comparison signal; ​ The selection circuit receives the first comparison signal and the second comparison signal, and also receives the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal, and the second inductor current detection signal. The selection circuit outputs one of the first inductor current sampling signal and the first inductor current detection signal according to the first comparison signal; and outputs one of the second inductor current sampling signal and the second inductor current detection signal according to the second comparison signal.

10. A control circuit of a switching power supply, the switching power supply includes a main switching transistor and an inductor connected to each other. Characterized in that, Comprising: An inductor current sampling circuit samples the current information of the inductor to obtain a first inductor current sampling signal of the main switching transistor during the on-time and a second inductor current sampling signal during the off-time; A current signal selection circuit receives the first inductor current sampling signal and the second inductor current sampling signal, and detects the switching time of the main switching transistor. When it is detected that the on-time of the main switching transistor is less than a first threshold time, during the on-time of the main switching transistor, a first inductor current detection signal is obtained according to the second inductor current sampling signal and the input voltage of the power stage circuit in the switching power supply or the input voltage and the output voltage, and the first inductor current detection signal and the second inductor current sampling signal are output as output signals. When it is detected that the off-time of the main switching transistor is less than a second threshold time, during the off-time of the main switching transistor, a second inductor current detection signal is obtained according to the first inductor current sampling signal and the output voltage of the power stage circuit of the switching power supply, and the second inductor current detection signal and the first inductor current sampling signal are output as output signals. When it is detected that the on-time of the main switching transistor is greater than the first threshold time and the off-time is greater than The second threshold time, the first inductor current sampling signal and the second inductor current sampling signal are output.

11. The control circuit according to claim 10, Characterized in that, The current signal selection circuit includes a switching time detection circuit, a first inductor current reconstruction circuit, a second inductor current reconstruction circuit, and a selection circuit. The switching time detection circuit detects the switching time of the main switching transistor, and receives the first inductor current sampling signal and the second inductor current sampling signal to select whether to output the first inductor current sampling signal or the second inductor current sampling signal to the subsequent circuit according to the switching time. When the first inductor current reconstruction circuit receives the second inductor current sampling signal output by the switching time detection circuit, a first ramp voltage signal is constructed according to the operation of the input voltage of the power stage circuit or the input voltage and the output voltage, and the first inductor current detection signal is obtained after the operation of the second inductor current sampling signal and the first ramp voltage signal. When the second inductor current reconstruction circuit receives the first inductor current sampling signal output by the switching time detection circuit, a second ramp voltage signal is constructed based on the operation of the output voltage of the power stage circuit. After the first inductor current sampling signal and the second ramp voltage signal are operated, the second inductor current detection signal is obtained; The selection circuit outputs the first inductor current detection signal and the second inductor current sampling signal according to the switching time detection result of the switching time detection circuit, or alternatively, selects to output the second inductor current detection signal and the first inductor current sampling signal, or outputs the first inductor current sampling signal and the second inductor current sampling signal.

12. The control circuit according to claim 11, wherein, the first inductor current reconstruction circuit includes an up-ramp current reconstruction circuit and a superposition circuit, the up-ramp current reconstruction circuit constructs a first ramp current signal that is proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the topology of the power stage circuit of the switching power supply, the superposition circuit receives the second inductor current sampling signal and the first ramp current signal, and performs superposition processing to obtain the first inductor current detection signal.

13. The control circuit according to claim 12, wherein, the up-ramp current reconstruction circuit includes a first current source, a first charging capacitor, and a first switch connected in parallel with the first charging capacitor, the first current source is used to charge the first charging capacitor, and the voltage signal across the first charging capacitor is a first ramp voltage signal representing the first ramp current signal, wherein, the magnitude of the first current source is set to be proportional to the input voltage of the power stage circuit or the difference between the input voltage and the output voltage based on the topology of the power stage circuit, and the switching state of the first switch is opposite to the switching state of the main switch tube.

14. The control circuit according to claim 13, wherein, during the conduction period of the main switch tube, the first charging capacitor is charged by the first current source until the end of the conduction time; during the off period of the main switch tube, the first charging capacitor is discharged to zero.

15. The control circuit according to claim 11, wherein, the second inductor current reconstruction circuit includes a down-ramp current reconstruction circuit and a subtraction circuit, the down-ramp current reconstruction circuit constructs a second ramp current signal that is proportional to the output voltage of the power stage circuit based on the topology of the power stage circuit of the switching power supply; the subtraction circuit receives the first inductor current sampling signal and the second ramp current signal, and performs subtraction processing to obtain the second inductor current detection signal.

16. The control circuit according to claim 15, wherein, the down-ramp current reconstruction circuit includes a second current source, a second charging capacitor, and a second switch connected in parallel with the second charging capacitor, The second current source is used to charge the second charging capacitor, and the voltage signal across the two ends of the second charging capacitor is a second ramp voltage signal characterizing the second ramp current signal. Wherein, the magnitude of the current source is set in a proportional relationship with the output voltage of the power stage circuit, and the switching state of the second switch is the same as the switching state of the main switch tube.

17. The control circuit according to claim 16, characterized in that During the off-time of the main switch tube, the second current source charges the second charging capacitor, and during the on-time of the main switch tube, the second charging capacitor discharges to zero.

18. The control circuit according to any one of claims 11-17, characterized in that The switching time detection circuit includes a switching time acquisition circuit, a comparison circuit and a switching circuit. The switching time acquisition circuit receives the switching control signal of the main switch tube to obtain the on-time and off-time of the main switch tube according to the switching control signal; The comparison circuit receives the on-time and a preset first threshold time, and compares them to obtain a first comparison signal; Receives the off-time and a preset second threshold time, and compares them to obtain a second comparison signal; The switching circuit receives the first comparison signal, the second comparison signal, and also receives the first inductor current sampling signal and the second inductor current sampling signal. The switching circuit decides whether to output the first inductor current sampling signal to the subsequent stage circuit according to the first comparison signal; decides whether to output the second inductor current sampling signal to the subsequent stage circuit according to the second comparison signal.

19. A control method for a switching power supply, the switching power supply includes a main switch tube and an inductor connected to each other. characterized in that including the steps of: S1: Sampling the current information of the inductor to obtain a first inductor current sampling signal of the main switch tube during the on-time and a second inductor current sampling signal during the off-time; S2: Receiving the first inductor current sampling signal, and during the off-time of the main switch tube, obtaining a second inductor current detection signal according to the first inductor current sampling signal and the output voltage of the power stage circuit; And receiving the second inductor current sampling signal, and during the on-time of the main switch tube, obtaining a first inductor current detection signal according to the second inductor current sampling signal and the input voltage of the power stage circuit or the operation of the input voltage and the output voltage; S3: Deciding to output one of the first inductor current sampling signal and the first inductor current detection signal as an output signal to the subsequent stage circuit according to the comparison result of the on-time of the main switch tube and a preset first threshold time. And, the current signal selection circuit decides to output one of the second inductor current sampling signal and the second inductor current detection signal as an output signal to the subsequent stage circuit according to the comparison result of the off-time of the main switch tube and a preset second threshold time.

20. The control method according to claim 19, characterized in that further includes Receive the second inductor current sampling signal, and construct a first ramp current signal that is proportional to the input voltage of the power stage circuit or the operation of the input voltage and the output voltage. After the second inductor current sampling signal and the first ramp current signal are operated, the first inductor current detection signal is obtained; Receive the first inductor current sampling signal, and construct a second ramp current signal that is proportional to the output voltage of the power stage circuit. After the first inductor current sampling signal and the second ramp current signal are operated, the second inductor current detection signal is obtained, Detect the switching time of the main switch tube, and receive the first inductor current sampling signal, the second inductor current sampling signal, the first inductor current detection signal, and the second inductor current detection signal to select the output signal according to the switching time.

21. A control method for a switching power supply, the switching power supply includes a main switch tube and an inductor connected to each other, Characterized in that, S1: Sample the current information of the inductor to obtain a first inductor current sampling signal of the main switch tube during the on-time and a second inductor current sampling signal during the off-time; S2: Receive the first inductor current sampling signal and the second inductor current sampling signal, and detect the switching time of the main switch tube, When it is detected that the on-time of the main switch tube is less than the first threshold time, during the on-time of the main switch tube, operate according to the second inductor current sampling signal and the input voltage of the power stage circuit or the input voltage and the output voltage to obtain a first inductor current detection signal, and use the first inductor current detection signal and the second inductor current sampling signal as the output signal for output, When it is detected that the off-time of the main switch tube is less than the second threshold time, during the off-time of the main switch tube, operate according to the first inductor current sampling signal and the output voltage of the power stage circuit to obtain a second inductor current detection signal, and use the second inductor current detection signal and the first inductor current sampling signal as the output signal for output, When it is detected that the on-time of the main switch tube is greater than the first threshold time and the off-time is greater than the second threshold time, output the first inductor current sampling signal and the second inductor current sampling signal.

22. The control method according to claim 21, Characterized in that, It further includes the step of, Detect the switching time of the main switch tube, and receive the first inductor current sampling signal and the second inductor current sampling signal to select whether to output the first inductor current sampling signal or the second inductor current sampling signal to the subsequent circuit according to the switching time, When the second inductor current sampling signal is received, construct a first ramp voltage signal that is proportional to the operation of the input voltage of the power stage circuit or the input voltage and the output voltage. After the second inductor current sampling signal and the first ramp voltage signal are operated, the first inductor current detection signal is obtained; When the first inductor current sampling signal is received, a second ramp voltage signal proportional to the output voltage of the power stage circuit is constructed, and the second inductor current detection signal is obtained after the first inductor current sampling signal and the second ramp voltage signal are operated on; The first inductor current detection signal and the first inductor current sampling signal are output according to the switching time detection result of the switching time detection circuit, or alternatively, the second inductor current detection signal and the second inductor current detection signal are selected to be output, or the first inductor current sampling signal and the second inductor current sampling signal are output.

23. A switching power supply, characterized in that, it includes the control circuit according to any one of claims 1-18, and further includes a comparison circuit and a logic and drive circuit, the comparison circuit includes a first comparator and a second comparator, the first comparator receives the first inductor current detection signal or the first inductor current sampling signal transmitted by the control circuit to compare with a first reference voltage signal to obtain a first comparison signal; the second comparator receives the second inductor current detection signal or the second inductor current sampling signal transmitted by the control circuit to compare with a second reference voltage signal to obtain a second comparison signal; the logic and drive circuit receives the first comparison signal and the second comparison signal, and accordingly generates a switching control signal for controlling the switching state of the main switching transistor in the switching power supply.

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