Current sensing circuit and related current mode control circuit

Abstract

The present invention provides a current detection circuit, which includes an inductor current detection circuit and a processing circuit. The inductor current detection circuit detects the inductor current of a direct current to direct current (DC‑DC) converter to generate a first detection current signal, wherein the average value of the first detection current signal is not constant under different input voltages of the DC‑DC converter. The processing circuit generates a second detection current signal, wherein the first detection current signal participates in the generation of the second detection current signal, the second detection current signal participates in the current mode control of the DC‑DC converter, and the average value of the second detection current signal is constant under different input voltages of the DC‑DC converter. Accordingly, the present invention also provides a current mode control circuit for a DC‑DC converter. The solution provided by the present invention can take into account both low compensation hardware cost and good line regulation / transient performance.

Description

Technical Field

[0001] The present invention relates to a direct current to direct current (DC-DC) converter design, and more particularly, to a current sensing circuit and an associated current mode control circuit for generating a sensed current signal with a constant average value under different input voltages of the DC-DC converter. Background Art

[0002] Portable battery-powered devices are becoming increasingly popular. Lightweight and long battery runtime are key requirements for devices such as smartphones, tablets, and wearables. Battery modules have become a major component in the space and weight of these portable devices. Typically, the display panel of a portable device is powered by the battery module via a DC-DC converter. For example, the display panel can be an active-matrix organic light-emitting diode (AMOLED) panel, and an inverting buck-boost converter is used to provide the required negative voltage to the AMOLED panel. This negative voltage is converted from the positive supply voltage of the battery module. Therefore, the display quality of the display panel depends on the line regulation and transient performance of the DC-DC converter. For DC-DC converters, pulse-width modulation (PWM) is typically used to control the output voltage. Using a typical voltage-mode PWM control scheme, the DC-DC converter can achieve good line transient performance, but this requires higher compensation hardware costs. In another case, with a typical current-mode PWM control scheme, the DC-DC converter can save compensation hardware costs but suffers from poor line regulation / transient performance.

[0003] Therefore, an advanced current-mode PWM control scheme is needed that enables DC-DC converters to benefit from the low compensation hardware cost of current-mode PWM control while maintaining good line regulation / transient performance. Summary of the Invention

[0004] In view of the above, one of the objects of the present invention is to provide a current sensing circuit and a related current mode control circuit for generating a sensing current signal with a constant average value under different input voltages of a DC-DC converter, which has the advantages of low compensation hardware cost and good line regulation / transient performance.

[0005] According to a first aspect of the present invention, an exemplary current detection circuit is disclosed. The exemplary current detection circuit includes an inductor current detection circuit and a processing circuit. The inductor current detection circuit is configured to detect an inductor current of a DC-DC converter to generate a first detection current signal, wherein an average value of the first detection current signal is not constant under different input voltages of the DC-DC converter. The processing circuit is configured to generate a second detection current signal, wherein the first detection current signal participates in generating the second detection current signal, the second detection current signal participates in current-mode control of the DC-DC converter, and the average value of the second detection current signal is constant under different input voltages of the DC-DC converter.

[0006] In one embodiment, the processing circuit includes: a load current detection circuit for detecting the load current of the DC-DC converter to generate a third detection current signal; and an adjustment circuit for deriving an AC component from the first detection current signal and generating the second detection current signal by combining the third detection current signal and the AC component.

[0007] In one embodiment, the AC component is equal to half of the peak-to-peak ripple current amplitude of the first detection current signal.

[0008] In one embodiment, the processing circuit includes: an adjustment signal generating circuit for generating an adjustment signal; and a combining circuit for generating the second detection current signal by subtracting the adjustment signal from the first detection current signal.

[0009] In one embodiment, the adjustment signal generating circuit generates the adjustment signal according to an average value of the first detection current signal and a duty cycle controlled by the current mode control.

[0010] In one embodiment, the adjustment signal generating circuit generates the adjustment signal according to the load current of the DC-DC converter, the input voltage of the DC-DC converter, and the output voltage of the DC-DC converter.

[0011] In one embodiment, the DC-DC converter is an inverting buck-boost converter.

[0012] According to a second aspect of the present invention, an exemplary current-mode control circuit for a DC-DC converter is disclosed. The exemplary current-mode control circuit includes an error amplifier circuit, a current detection circuit, a ramp wave generating circuit, a first combination circuit, and a comparator circuit. The error amplifier circuit is configured to receive a feedback voltage and a reference voltage from the DC-DC converter and generate an error signal based on the feedback voltage and the reference voltage. The current detection circuit includes an inductor current detection circuit and a processing circuit. The inductor current detection circuit is configured to detect the inductor current of the DC-DC converter to generate a first detection current signal, wherein the average value of the first detection current signal is not constant under different input voltages of the DC-DC converter. The processing circuit is configured to generate a second detection current signal, wherein the first detection current signal contributes to the generation of the second detection current signal, and the average value of the second detection current signal is constant under different input voltages of the DC-DC converter. The ramp wave generating circuit is configured to generate a ramp wave signal. The first combination circuit is configured to combine the second detection current signal and the ramp wave signal to generate a summation signal. The comparator circuit is used for receiving the error signal and the sum signal, and generating a control signal according to the error signal and the sum signal, wherein the output voltage of the DC-DC converter depends on the control signal.

[0013] In one embodiment, the processing circuit includes: a load current detection circuit for detecting the load current of the DC-DC converter to generate a third detection current signal; and an adjustment circuit for deriving an AC component from the first detection current signal and generating the second detection current signal by combining the third detection current signal and the AC component.

[0014] In one embodiment, the AC component is equal to half of the peak-to-peak ripple current amplitude of the first detection current signal.

[0015] In one embodiment, the processing circuit includes: an adjustment signal generating circuit for generating an adjustment signal; and a second combining circuit for generating the second detection current signal by subtracting the adjustment signal from the first detection current signal.

[0016] In one embodiment, the adjustment signal generating circuit generates the adjustment signal according to an average value of the first detection current signal and a duty cycle controlled by the control signal.

[0017] In one embodiment, the adjustment signal generating circuit generates the adjustment signal according to the load current of the DC-DC converter, the input voltage of the DC-DC converter, and the output voltage of the DC-DC converter.

[0018] In one embodiment, the DC-DC converter is an inverting buck-boost converter.

[0019] Those skilled in the art will readily appreciate these and other objects of the present invention after reading the following detailed description of the preferred embodiments shown in the accompanying drawings. Detailed description will be given in the following embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] A more complete understanding of the present invention may be obtained by reading the following detailed description and referring to the examples given in the accompanying drawings.

[0021] Figure 1 FIG. 1 is a block diagram of a current detection circuit according to an embodiment of the present invention.

[0022] Figure 2 The present invention provides a current mode control circuit for a DC-DC converter.

[0023] Figure 3 According to the condition V SUM =I SEN +I RAMP Figure 2 shows the waveforms of different signals of the DC-DC converter.

[0024] Figure 4 According to an embodiment of the present invention, under the condition V SUM =I ASEN +I RAMP The waveforms of different signals of the DC-DC converter are shown below.

[0025] Figure 5 According to the embodiment of the present invention Figure 1 Schematic diagram of a first exemplary design of a current sensing circuit is shown in .

[0026] Figure 6 According to the embodiment of the present invention Figure 1 Schematic diagram of a second exemplary design of a current sense circuit is shown in .

[0027] In the following detailed description, for illustrative purposes, numerous specific details are set forth to enable those skilled in the art to more thoroughly understand the embodiments of the present invention. However, it is apparent that one or more embodiments may be practiced without these specific details, and different embodiments may be combined as needed, and the present invention should not be limited to the embodiments illustrated in the accompanying drawings. DETAILED DESCRIPTION

[0028] The following description is of preferred embodiments of the present invention and is intended only to illustrate the technical features of the present invention and is not intended to limit the scope of the invention. Certain terms are used throughout the specification and claims to refer to specific components. Those skilled in the art will appreciate that manufacturers may use different names for the same components. Therefore, this specification and claims do not distinguish components by name, but rather by functional differences. The terms "component," "system," and "device" used in this invention may refer to entities related to a computer, which may be hardware, software, or a combination of hardware and software. The terms "including" and "comprising" used in the following description and claims are open-ended and should be interpreted as meaning "including, but not limited to..." Furthermore, the term "coupled" refers to an indirect or direct electrical connection. Therefore, when a device is described as being coupled to another device, this means that the device may be directly electrically connected to the other device or indirectly electrically connected to the other device through other devices or connections.

[0029] Corresponding numerals and symbols in the various figures of the drawings generally refer to corresponding parts unless otherwise indicated. The drawings are drawn to clearly illustrate the relevant parts of the embodiments and are not necessarily drawn to scale.

[0030] As used herein, the terms "substantially" or "approximately" mean that a person skilled in the art is able to solve the desired technical problem and substantially achieve the desired technical effect within an acceptable range. For example, "approximately equal to" means that a certain deviation from "exactly equal to" is acceptable to a person skilled in the art without affecting the accuracy of the result.

[0031] Figure 1 1 is a block diagram of a current sensing circuit according to an embodiment of the present invention. The current sensing circuit 100 can be used to implement the advanced current mode PWM control proposed by the present invention. Compared with typical current mode PWM control, the advanced current mode PWM control (provided by the present invention) enables the DC-DC converter to benefit from the low compensation hardware cost of current mode PWM control while maintaining good line regulation / transient performance. Figure 1As shown, the current detection circuit 100 includes an inductor current sensing circuit 102 and a processing circuit 104. The inductor current sensing circuit 102 is arranged to sense a DC-DC converter (e.g., an inverting buck-boost converter having a power stage 10 for sensing a positive input voltage V IN Generates a negative output voltage V OUT , and is used to provide a constant load current I drawn by the load device LOAD ) inductor L inductor current I L , to generate a sensed current signal I SEN , where the detection current signal I SEN The average value of the DC-DC converter at different input voltages V IN In other words, when the input voltage V IN When the current signal I SEN The average value of the detection current signal I SEN The average value of is also changing. For example, the inductor current detection circuit 102 can be implemented by a current sensing amplifier, which is used to detect the inductor current I when the metal-oxide-semiconductor (MOS) transistor DH (which serves as a high-side switch) is turned on and the MOS transistor DL ​​(which serves as a low-side switch) is turned off. L According to actual design considerations, the detection current signal I SEN It can be expressed in "voltage" form or "current" form.

[0032] The processing circuit 104 is used to generate another detection current signal I ASEN As the detection output of the current detection circuit 100, the detection current signal I SEN Participate in the detection of current signal I ASEN The generation of the detection current signal I ASEN Participate in the current mode control of the DC-DC converter (especially the current mode PWM control of the MOS transistors DH and DL in the DC-DC converter), and detect the current signal I ASEN The average value of the DC-DC converter at different input voltages V IN That is, in the embodiment of the present invention, the processing circuit 104 is based on the first detection current signal I SEN Generate a second detection current signal IASEN , and the current mode control of the DC-DC converter is based on the second detection current signal I ASEN The first detection current signal I SEN The average value of the DC-DC converter at different input voltages V IN is not constant, and the second detection current signal I ASEN The average value of the DC-DC converter at different input voltages V IN The current signal I is constant. SEN Compared with the typical current mode PWM control, the advanced current mode PWM control proposed in this invention uses the detection current signal I ASEN Further details of the advanced current mode PWM control are described below with reference to the accompanying drawings.

[0033] Figure 2 The current-mode control circuit 200 is a current-mode control circuit of a DC-DC converter according to an embodiment of the present invention. For example, the current-mode control circuit 200 may be a current-mode PWM controller, and / or may be a current-mode PWM controller having Figure 1 The inverting buck-boost converter of the power stage 10 shown is used. The current mode control circuit 200 may include Figure 1 The current detection circuit 100 shown may further include an error amplifier circuit (labeled “EA”) 202, a ramp generator circuit 204, a combining circuit 206, and a comparator circuit (labeled “CMP”) 208. The error amplifier circuit 202 is arranged to receive a feedback voltage V FB and reference voltage V REF , and according to the feedback voltage V FB and reference voltage V REF Generate error signal V COMP For example, the feedback voltage V FB The output voltage V of the DC-DC converter can be adjusted by a voltage divider. OUT The feedback voltage V FB With reference voltage V REF The comparison result determines the error signal V COMP voltage level.

[0034] The ramp wave generating circuit 204 is arranged to generate a ramp wave signal I having a periodic sawtooth wave or a triangle wave. RAMPFor example, the ramp wave generating circuit 204 may refer to the input voltage V IN and reference voltage V REF To generate a ramp signal I with a dynamic slope RAMP The combination circuit 206 is used to combine the detection current signal I ASEN and ramp signal I RAMP To generate the summation signal V SUM (For example, V SUM =I ASEN +I RAMP ). For example, the sum signal V SUM It can be expressed in the form of "voltage". It should be noted that if the detection current signal I ASEN With ramp signal I RAMP In the form of “current”, the combination circuit 206 can have a current-voltage conversion function to generate a summation signal V SUM .

[0035] The comparator circuit 208 is used to receive the error signal V COMP and summation signal V SUM , and according to the error signal V COMP and summation signal V SUM Generate control signal V SW (It is the comparator output). Control signal V SW It is the PWM control signal and is used to determine the on-time period t of the MOS transistor DH. ON and off-time period t OFF , where the duty cycle D is given by Therefore, the output voltage of the DC-DC converter is V OUT Depends on the control signal V SW .

[0036] Since the present invention focuses on the innovative design of the current detection circuit 100 and the error amplifier circuit 202, the ramp wave generating circuit 204, the combination circuit 206, and the comparator circuit 208 can be implemented using any known design. Therefore, for the sake of brevity, further description of the error amplifier circuit 202, the ramp wave generating circuit 204, the combination circuit 206, and the comparator circuit 208 is omitted here.

[0037] Typical current mode PWM control directly uses the sensed current signal I SEN Therefore, the line transient performance and line regulation performance of the DC-DC converter using the typical current mode PWM control are very poor. The present invention considers modifying the current detection circuit 100 to output the detection current signal I ASEN Instead of the recommended detection current signal ISEN Thus, the summation signal V output from the combination circuit 206 is SUM =I ASEN +I RAMP . Figure 3 For the condition V SUM =I SEN +I RAMP The waveforms of different signals of the DC-DC converter are shown below. Input voltage V IN It can be provided by a battery device that is shared by multiple components in the same portable device. Therefore, the input voltage V IN It may be affected by input voltage disturbances or transients caused by one or more components. Assume that the DC-DC converter is an inverting buck-boost converter operating in continuous-conduction mode (CCM). Therefore, the duty cycle D can be expressed as: Among them, the input voltage V IN is a positive voltage (ie V IN >0V), and the output voltage V OUT Negative voltage (V OUT <0V). In addition, the inductor current I L The average value of I L,AVG It can be expressed as The load current I drawn by the load device (eg, AMOLED panel) is LOAD Has a fixed current value, and with the input voltage V IN Not relevant.

[0038] like Figure 3 As shown, when the input voltage V IN With an input voltage disturbance or transient (e.g., a transition from a current voltage level to a lower voltage level), the current mode PWM control is operated to increase the duty cycle D for the same output voltage. Therefore, the inductor current I L Peak I L,PEAK and the average value I L,AVG All increase due to the increase of duty cycle D. Since the detection current signal I SEN By detecting the inductor current I L (In particular, during the on-time t ON The inductor current I is detected during L ) to obtain the detection current signal I SEN Peak I S,PEAK and the average value I S,AVG All increase, among which, the detection current signal I SEN The average value of I S,AVG and the inductor current I L The average value of I L,AVGPositive correlation. The duty cycle D depends on the error signal V COMP and the summation signal V SUM The comparison of the conduction time of the MOS transistor DH is t ON The end point of the summation signal V SUM The peak value of the error signal V COMP In typical current mode PWM control, the error signal V COMP and the summation signal V SUM The relationship between SUM =I SEN +I RAMP ) can be expressed by the following formula, where:

[0039]

[0040] In the above formula (1), I L,PP Indicates the inductor current I L Since the current mode PWM control is operated in response to the input voltage V IN The duty cycle D is increased by switching from the current voltage level to a lower voltage level, so the inductor current I L The change in ΔI L,AVG , detect current signal I SEN The change in ΔI S,AVG and the error signal V COMP Specifically, the duty cycle D will change with the input voltage V IN Factor The error signal V COMP The effect of the change in ΔVCOMP is negligible, and, The average value of can be considered as a constant under different input voltages of the DC-DC converter. However, the factor (i.e., IL,AVG) dominates the error signal V COMP (i.e., ΔVCOMP≈ΔIL,AVG), and The average value of is not constant under different input voltages of the DC-DC converter. IN When there is an input voltage disturbance or transient, a large change ΔVCOMP within a time period Δt will result in a large output voltage change (i.e., the output voltage V OUT Therefore, when the input voltage V INWhen subjected to input voltage disturbances or transients, DC-DC converters using typical current-mode PWM control have poor line transient performance.

[0041] In order to solve this problem, the advanced current mode PWM control proposed in the present invention uses the detection current signal I ASEN Instead of using the detection current signal I SEN . Figure 4 The DC-DC converter according to the embodiment of the present invention is shown in the condition V SUM =I ASEN +I RAMP As mentioned above, the input voltage V provided by the power supply (eg, battery module) is IN It may be affected by input voltage disturbances or transients. Assume that the DC-DC converter is an inverting buck-boost converter operating in continuous conduction mode (CCM). The duty cycle D can be given by Indicates that, where the input voltage V IN is a positive voltage (ie V IN >0V), output voltage V OUT Negative voltage (V OUT <0V). In addition, the inductor current I L The average value I L,AVG It can be expressed as The load current I drawn by the load device (eg, AMOLED panel) is LOAD Has a fixed current value regardless of the input voltage V IN How. Figure 4 As shown, when the input voltage V IN With an input voltage disturbance or transient (e.g., a transition from the current voltage level to a lower voltage level), current mode PWM control is used to increase the duty cycle D for the same output voltage. Therefore, the inductor current I L Peak I L,PEAK and the average value I L,AVG All increased.

[0042] As an example and not a limitation, the current signal I SEN Subtract the adjustment signal I FF To generate the detection current signal I ASEN , where the detection current signal I SEN By detecting the inductor current I L (In particular, during the on-time t ON The inductor current I is detected during L ) is obtained. Using the adjustment signal I FF With proper setting, the detection current signal I ASEN Peak IAS,PEAK and the average value I AS,AVG At the input voltage V IN It will not change even when there is input voltage disturbance or transient. Therefore, the detection current signal I ASEN The average value of I AS,AVG The change in ΔI AS,AVG is essentially zero, and the detection current signal I ASEN The change in the peak-to-peak ripple current amplitude ΔI AS,PP Basically zero.

[0043] The conduction time t of MOS transistor DH is ON The end point can be compared with the summation signal V SUM The peak value of the error signal V COMP The error signal V COMP and summation signal V SUM The relationship between (for example, V SUM =I RAMP +(I SEN -I FF ) can be expressed by the following formula, where and

[0044]

[0045] When adjusting the signal I FF is set to When , the above formula can be rewritten as:

[0046]

[0047] For directly using the detection current signal I SEN Typical current mode PWM control, the factor in formula (1) Dominate error signal V COMP Change of ΔV COMP However, by intentionally introducing a cancellation factor I FF Regardless of the input voltage of the DC-DC converter, the detection current signal have a constant mean value, and the factor Does not exist in formula (3). Since the detection current signal I ASEN Change in ΔI AS,AVG is essentially zero, so the input voltage V IN The error signal V COMP Change of ΔV COMPis very small (i.e. ΔVCOMP≈ΔIAS, PP≈0). In other words, by adjusting the signal I FF The intentionally introduced change ΔIFF can offset or mitigate the error signal V COMP Change of ΔV COMP It should be noted that, from the detection current signal I SEN Subtract the adjustment signal I FF It generates a detection current signal with a constant average value I ASEN In fact, any system that can process the detection current signal I SEN To generate a detection current signal I with a constant average value ASEN The advanced current mode PWM control proposed by the present invention can be adopted by all of the above methods. IN When there is a disturbance or transient in the input voltage, a small change ΔV within a time period Δt COMP The output voltage changes very little (ie the output voltage V OUT Thus, when the input voltage V IN The DC-DC converter using the proposed advanced / high-level current mode PWM control has good line transient performance when subjected to input voltage disturbances or transients.

[0048] As mentioned above, the processing circuit 104 is designed to generate the detection current signal I ASEN As the sensing output of the current detection circuit 100, the detection current signal I ASEN The average value of the DC-DC converter (e.g., inverting buck-boost converter) at different input voltages V IN The bottom is constant. Figure 5 According to the embodiment of the present invention Figure 1 Schematic diagram of a first exemplary design of a current detection circuit is shown in FIG. Processing circuit 104 may be configured to include a load current sensing circuit 502 and an adjusting circuit 504. Load current sensing circuit 502 is arranged to sense a load current I of a DC-DC converter (e.g., an inverting buck-boost converter). LOAD , to generate the detection current signal I SEN,LOAD For example, the load current detection circuit 502 may be configured to sense the load current I LOAD The current sensing amplifier is implemented, where the load current I LOAD Has a fixed current value regardless of the input voltage V IN How. According to actual design considerations, the detection current signal I SEN,LOADIt can be expressed in the form of "voltage" or "current". The adjustment circuit 504 is used to adjust the current signal I SEN The alternating current (AC) component I is derived from SEN,AC and by detecting the current signal I SEN,LOAD With AC component I SEN,AC Combined to generate the detection current signal I ASEN , that is, I ASEN =I SEN,AC +I SEN,LOAD For example, the AC component I SEN,AC Can be equal to the detection current signal I SEN The detection current signal I ASEN Including the inductor current I for current mode PWM control L information, but is free from input-voltage-dependent factors that significantly degrade line transient performance In other words, the DC-DC converter (e.g., inverting buck-boost converter) retains the current information and the weight of the current mode characteristics (e.g., saving hardware compensation cost) and reduces the error signal V COMP Change of ΔV COMP , to improve line regulation / transient performance. In addition, Figure 5 The illustrated current sensing circuit 100 may be implemented using a single circuit design.

[0049] Figure 6 According to the embodiment of the present invention Figure 1 Schematic diagram of a second exemplary design of a current detection circuit is shown in FIG. The processing circuit 104 may be configured to include an adjustment signal generator circuit 602 and a combining circuit 604. The adjustment signal generator circuit 602 is configured to generate an adjustment signal I FF Adjust signal I FF It can be expressed in "voltage" form or "current" form, depending on the actual design considerations. The combination circuit 604 is used to detect the current signal I SEN Subtract the adjustment signal I FF To generate the detection current signal I ASEN , that is I ASEN =I SEN -I FF For example, the adjustment signal generating circuit 602 can adjust the current signal I SEN The average value and the duty cycle D controlled by the current mode PWM control generate the adjustment signal IFF In the case where the DC-DC converter is an inverting buck-boost converter operating in CCM, the duty cycle D can be expressed as Alternatively, the adjustment signal generating circuit 602 may adjust the load current I LOAD , DC-DC converter input voltage V IN and the output voltage V of the DC-DC converter OUT Generate adjustment signal I FF . Detection current signal I ASEN Including the inductor current I for current mode PWM control L information, but is not subject to input voltage related factors that significantly degrade line transient performance In other words, the DC-DC converter (e.g., inverting buck-boost converter) retains the current information and the weight of the current mode characteristics (e.g., saving hardware compensation cost) and reduces the error signal V COMP Change of ΔV COMP , to improve line regulation / transient performance. In addition, Figure 6 The illustrated current sensing circuit 100 may be implemented using a single circuit design.

[0050] Figure 5 and Figure 6 The embodiment shown is for illustration purposes only and is not intended to limit the present invention. ASEN (By detecting the current signal I SEN Derived) at different input voltages V IN With a constant average value, the error signal V COMP Change of ΔV COMP can be mitigated to reduce output voltage variation, such as Figure 4 In fact, any detection current signal I ASEN All current mode PWM controllers should fall within the scope of the present invention.

[0051] For the sake of simplicity, the DC-DC converter using the proposed current mode control design is described by taking an inverting buck-boost converter as an example. However, this does not mean that it is limiting the present invention. In fact, any converter using the detection current signal I ASEN Any DC-DC converter that performs current mode PWM control (which has a constant average value) should fall within the scope of the present invention.

[0052] Although the present invention has been described by way of example and in terms of preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and similar configurations (as will be apparent to those skilled in the art), for example, combinations or substitutions of different features from different embodiments. Accordingly, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar configurations.

Claims

1. A current detection circuit, characterized in that: include: an inductor current detection circuit for detecting an inductor current of a DC-DC converter to generate a first detection current signal, wherein an average value of the first detection current signal is not constant under different input voltages of the DC-DC converter, the DC-DC converter being an inverting buck-boost converter; and A processing circuit is configured to generate a second detection current signal based on the first detection current signal, wherein the second detection current signal is used for current mode control of the DC-DC converter, and an average value of the second detection current signal is constant under different input voltages of the DC-DC converter.

2. The current detection circuit according to claim 1, wherein: The processing circuit includes: a load current detection circuit, configured to detect the load current of the DC-DC converter to generate a third detection current signal; and The regulating circuit is configured to derive an alternating current (AC) component from the first detection current signal and generate the second detection current signal by combining the third detection current signal and the AC component.

3. The current detection circuit according to claim 2, wherein: The AC component is equal to half of the peak-to-peak ripple current amplitude of the first detection current signal.

4. The current detection circuit according to claim 1, wherein: The processing circuit includes: an adjustment signal generating circuit, configured to generate an adjustment signal; and The combination circuit is configured to generate the second detection current signal by subtracting the adjustment signal from the first detection current signal.

5. The current detection circuit according to claim 4, wherein: The adjustment signal generating circuit generates the adjustment signal according to an average value of the first detection current signal and a duty cycle controlled by the current mode control.

6. The current detection circuit according to claim 4, wherein: The adjustment signal generating circuit generates the adjustment signal according to the load current of the DC-DC converter, the input voltage of the DC-DC converter and the output voltage of the DC-DC converter.

7. A current mode control circuit for a DC-DC converter, wherein: The current mode control circuit includes an error amplifier circuit, a current detection circuit, a ramp wave generating circuit, a first combination circuit and a comparator circuit. The error amplifier circuit is used to receive the feedback voltage and the reference voltage of the DC-DC converter and generate an error signal according to the feedback voltage and the reference voltage. The DC-DC converter is an inverting buck-boost converter. The current detection circuit includes an inductor current detection circuit and a processing circuit. The inductor current detection circuit is used to detect the inductor current of the DC-DC converter to generate a first detection current signal. The average value of the first detection current signal is not constant under different input voltages of the DC-DC converter. The processing circuit is used to generate a second detection current signal based on the first detection current signal. The second detection current signal is used for current mode control of the DC-DC converter. The average value of the second detection current signal is constant under different input voltages of the DC-DC converter. The ramp wave generating circuit is used to generate a ramp wave signal; The first combination circuit is used for combining the second detection current signal and the ramp signal to generate a summation signal; The comparator circuit is used for receiving the error signal and the sum signal, and generating a control signal according to the error signal and the sum signal, wherein the output voltage of the DC-DC converter depends on the control signal.

8. The current mode control circuit according to claim 7, wherein: The processing circuit includes: a load current detection circuit, configured to detect the load current of the DC-DC converter to generate a third detection current signal; and The regulating circuit is configured to derive an alternating current (AC) component from the first detection current signal and generate the second detection current signal by combining the third detection current signal and the AC component.

9. The current mode control circuit according to claim 8, wherein: The AC component is equal to half of the peak-to-peak ripple current amplitude of the first detection current signal.

10. The current mode control circuit according to claim 7, wherein: The processing circuit includes: an adjustment signal generating circuit, configured to generate an adjustment signal; and The second combination circuit is configured to generate the second detection current signal by subtracting the adjustment signal from the first detection current signal.

11. The current mode control circuit according to claim 10, wherein: The adjustment signal generating circuit generates the adjustment signal according to an average value of the first detection current signal and a duty cycle controlled by the control signal.

12. The current mode control circuit according to claim 10, wherein: The adjustment signal generating circuit generates the adjustment signal according to the load current of the DC-DC converter, the input voltage of the DC-DC converter and the output voltage of the DC-DC converter.

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