On-time control circuit and switch conversion system

Abstract

The invention provides a conduction time control circuit and a switch conversion system, and relates to the technical field of electrical control. For any sampling period, a ramp signal generation module in the turn-on time control circuit generates a ramp signal according to the input voltage; the peak value sampling module is used for acquiring the peak voltage of the ramp signal in the current sampling period; the error amplification module determines an error signal according to the peak voltage and the output voltage; the on-time generation module generates a state indication signal according to the error signal and the ramp signal, so that the charging module adjusts its own charging / discharging state according to the state indication signal to adjust the peak voltage of the ramp signal in the next sampling period, thereby improving the on-off time of a switching tube under the DC-DC converter. On the basis, on the basis of improving the accuracy of the on-off time of the converter, the problems of structural complexity and high power consumption of the control circuit can be reduced.

Description

Technical Field

[0001] This invention relates to the field of electrical control, and more specifically, to a conduction time control circuit and a switching system. Background Technology

[0002] Constant on / off time (COT) control mode in DC-DC converters is widely used in switching converters due to its excellent transient response and high efficiency under light load. Existing COT control modes typically generate a status indication signal (Ramp_OK) for controlling the switching converter using the input voltage Vin and the output voltage Vout, thereby causing the transistors in the switching converter to conduct alternately.

[0003] However, the conduction frequency varies significantly with the input voltage Vin and the output voltage Vout, greatly increasing the design complexity of the power supply's subsequent filter. While adding circuits that adaptively adjust the on-time or off-time according to the input and output voltages Vin and Vout can reduce the frequency variation of the DC-DC converter, in actual circuits, the offset voltage of the comparator and the delays in the logic circuits cause a deviation in the time required for the Ramp_OK signal, resulting in system frequency errors. Typically, engineers overcome this frequency deviation by adding a high-speed, low-offset voltage comparator, but this high-speed comparator increases system power consumption and complexity.

[0004] Therefore, there is an urgent need for an adaptive on-time control scheme that can improve the accuracy of on-time or off-time while reducing the problems of complex control circuit structure and high power consumption in existing technologies. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a conduction time control circuit and a switching conversion system. By setting an error amplification module, the system determines whether there is an error between the peak voltage of the ramp signal and the output voltage, and then improves the peak voltage of the ramp signal cycle by cycle based on the error signal. This reduces the complexity of the controller structure and improves the accuracy of the conduction time or turn-off time as the input voltage and output voltage change.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of the present invention are as follows: In a first aspect, this application provides an on-time control circuit applied to a switching conversion system, the switching conversion system including a DC-DC converter, and the on-time control circuit including a ramp signal generation module, a peak sampling module, an error amplification module, and an on-time generation module; the ramp signal generation module includes at least a charging module; The output of the ramp signal generation module is connected to the first input of the conduction time generation module and the input of the peak sampling module; the output of the peak sampling module is connected to the second input of the error amplification module; the output of the error amplification module is connected to the second input of the conduction time generation module; the output of the conduction time generation module is also connected to the control terminal of the charging module and the control terminal of the DC-DC converter; the first input of the error amplification module is used to receive the output voltage of the DC-DC converter; the input of the ramp signal generation module is used to receive the input voltage of the DC-DC converter. Among them, for any sampling period, the ramp signal generation module is used to generate a ramp signal based on the input voltage; The peak sampling module is used to acquire the peak voltage of the ramp signal in the current sampling period; The error amplification module is used to determine the error signal based on the peak voltage and the output voltage. The conduction time generation module is used to generate a status indication signal based on the error signal and the ramp signal; The charging module is used to adjust its own charging / discharging state according to the status indication signal so that the ramp signal generation module can generate a ramp signal.

[0007] Optionally, the on-time control circuit is also used to adjust the on-off time of the lower switching transistor of the DC-DC converter by changing the peak voltage of the ramp signal in the next sampling period according to the charging module.

[0008] Optionally, the error amplification module includes at least two operating states; the error signal includes multiple error commands, with each operating state corresponding to one error command. When the peak voltage of the ramp signal is greater than the output voltage in the current sampling period, the error amplification module is in the first working state, which is used to send the first error command to the conduction time generation module, drive the conduction time generation module to generate the first state command signal, adjust the charging / discharging state of the charging module, and reduce the peak voltage of the ramp signal in the next sampling period until the peak voltage is equal to the output voltage. And / or when the peak voltage of the ramp signal is less than the output voltage in the current sampling period, the error amplification module is in the second working state. It is also used to send a second error command to the conduction time generation module, drive the conduction time generation module to generate a second state command signal, adjust the charging / discharging state of the charging module, and increase the peak voltage of the ramp signal in the next sampling period until the peak voltage is equal to the output voltage.

[0009] Optionally, the charging module includes a charging capacitor and a first switching transistor. The control terminal of the first switching transistor is connected to the output terminal of the conduction time generation module to receive a status indication signal. The first terminal of the first switching transistor is connected to the first terminal of the charging capacitor. The first terminal of the charging capacitor serves as the output terminal of the ramp signal generation module and is connected to the first input terminal of the conduction time generation module and the input terminal of the peak sampling module. The second terminal of the charging capacitor and the second terminal of the first switching transistor are both grounded. The charging module is used to adjust the on / off state of the first switching transistor according to the status indication signal, thereby changing the charging / discharging state of the charging capacitor.

[0010] Optionally, the error amplification module includes a low-speed error amplifier; the first input terminal of the low-speed error amplifier is connected to the output terminal of the DC-DC converter to receive the output voltage of the DC-DC converter, the second input terminal of the low-speed error amplifier is connected to the output terminal of the peak sampling module to receive the peak voltage of the ramp signal; the output terminal of the error amplification module is connected to the second input terminal of the conduction time generation module. A low-speed error amplifier is used to amplify the difference between the output voltage and the peak voltage to generate an error signal at the output of the low-speed error amplifier.

[0011] Optionally, the conduction time generation module includes a first comparator; the first terminal of the first comparator is connected to the output terminal of the ramp signal generation module to receive the ramp signal; the second terminal of the first comparator is connected to the output terminal of the error amplification module to receive the error signal; and the output terminal of the first comparator is connected to the control terminal of the charging module. The first comparator is used to compare the ramp signal and the error signal to generate a status indication signal at the output of the first comparator.

[0012] Optionally, the peak sampling module includes a sample-and-hold circuit, the input of which is used to receive the ramp signal; the output of the sample-and-hold circuit is connected to the second input of the error amplification module. The sample-and-hold circuit is used to acquire the peak voltage of the ramp signal within one sampling period.

[0013] Optionally, the ramp signal generation module further includes a voltage conversion module, the output of which is connected to the charging module; the input of the voltage conversion module is used to receive the input voltage of the DC-DC converter; the first end of the charging module serves as the output of the ramp signal generation module and is connected to the first input of the conduction time generation module and the input of the peak sampling module; the control end of the charging module is also used to receive a status indication signal. The voltage conversion module is used to convert the input voltage into a current signal and then use the current signal to power the charging module.

[0014] Optionally, the ramp signal generation module further includes a current mirror module; the voltage conversion module includes a second error amplifier, a second switching transistor, a first capacitor, and a first resistor; the first input terminal of the second error amplifier is used to receive the input voltage; the second input terminal of the second error amplifier is connected to the first terminal of the second switching transistor and the first terminal of the first resistor; the output terminal of the second error amplifier is connected to the first terminal of the first capacitor and the control terminal of the second switching transistor; the second terminal of the second switching transistor is connected to the first terminal of the current mirror module; the second terminal of the current mirror module is connected to the first terminal of the charging module; the second terminals of the first resistor and the second terminal of the first capacitor are both grounded; The current mirror module is used to generate current to power the charging module based on the current signal provided by the voltage conversion module.

[0015] Secondly, this application also provides a switching conversion system, including a DC-DC converter and an on-time control circuit of any of the first aspects described above.

[0016] The conduction time control circuit and switching system provided in this invention have the following beneficial effects: This invention discloses a conduction time control circuit applied to a switching conversion system, including a DC-DC converter. The conduction time control circuit comprises a ramp signal generation module, a peak sampling module, an error amplification module, and a conduction time generation module. The ramp signal generation module includes at least a charging module. For any given sampling period, the ramp signal generation module generates a ramp signal based on the input voltage. The peak sampling module acquires the peak voltage of the ramp signal in the current sampling period. The error amplification module then determines an error signal based on the peak voltage and the output voltage. The conduction time generation module generates a status indication signal based on the error signal and the ramp signal. The charging module also adjusts its charging / discharging state based on the status indication signal to adjust the peak voltage of the ramp signal in the next sampling period, thereby adjusting the on / off time of the switching transistor in the DC-DC converter. Based on this, this application, by setting an error amplification module, improves the peak voltage of the ramp signal cycle by periodically adjusting the error between the peak voltage of the ramp signal and the output voltage. This reduces the complexity of the control device structure while improving the accuracy of the conduction or turn-off time as the input and output voltages change.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A block diagram of a switching conversion system provided in an embodiment of the present invention is shown; Figure 2 A block diagram of a conduction time control circuit provided in an embodiment of the present invention is shown; Figure 3 A second block diagram of the conduction time control circuit provided in an embodiment of the present invention is shown; Figure 4 A circuit diagram of a charging module provided in an embodiment of the present invention is shown; Figure 5 One of the circuit schematic diagrams of the conduction time control circuit provided in the embodiment of the present invention is shown; Figure 6 The third block diagram of the conduction time control circuit provided in the embodiment of the present invention is shown; Figure 7 This is a block diagram of a ramp signal generation module provided in an embodiment of the present invention; Figure 8 The second circuit schematic diagram of the conduction time control circuit provided in the embodiment of the present invention is shown; Figure 9 This is a second block diagram of the ramp signal generation module provided in an embodiment of the present invention; Figure 10 The third circuit schematic diagram of the conduction time control circuit provided in the embodiment of the present invention is shown; Figure 11 The following is a timing diagram of the conduction time control circuit provided in an embodiment of the present invention.

[0020] Icons: 10-Switch conversion system; 100-On-time control circuit; 200-DC-DC converter; 101-Slope signal generation module; 102-Peak sampling module; 103-Error amplification module; 104-On-time generation module; 201-Charging module; 202-Low-speed error amplifier; 203-Sample-and-hold circuit; 204-Voltage conversion module; 205-Voltage divider module; 206-Current mirror module; C1-Charging capacitor; Q1-First switch; Q2-Second switch; C2-First capacitor; R1-First resistor; R2-Second resistor; R3-Third resistor; U1-First comparator; U2-Second error amplifier; INV1-First logic inverter; INV2-Second logic inverter; M1-First transistor; M2-Second transistor. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0024] As described in the background section, circuits with varying on-time and off-time that change with input and output voltages have low accuracy, complex structures, and high power consumption. This embodiment provides an on-time control circuit and a switching system to overcome the aforementioned technical problems.

[0025] The following section will describe in detail the implementation of this adaptive on-time control scheme, using the diagram as an example.

[0026] Please refer to Figure 1 , Figure 1 A block diagram of the switching conversion system provided in this embodiment is shown. The switching conversion system 10 includes an on-time control circuit 100 and a DC-DC converter 200. The on-time control circuit 100 is used to generate a status indication signal based on the input voltage and the output voltage to adjust the on / off state of the switching transistor under the DC-DC converter 200.

[0027] Following the same approach as the previous embodiment, please... Figure 1 Based on, refer to Figure 2 , Figure 2 A block diagram of the conduction time control circuit provided in this embodiment is shown; the conduction time control circuit 100 includes a ramp signal generation module 101, a peak sampling module 102, an error amplification module 103, and a conduction time generation module 104; the ramp signal generation module 101 includes at least a charging module 201.

[0028] In this module, one end of the charging module 201 serves as the output of the ramp signal generation module 101, and is connected to the first input of the conduction time generation module 104 and the input of the peak sampling module 102. The output of the peak sampling module 102 is connected to the second input of the error amplification module 103. The output of the error amplification module 103 is connected to the second input of the conduction time generation module 104. The output of the conduction time generation module 104 is also connected to the control terminal of the charging module 201 and the control terminal of the DC-DC converter 200.

[0029] In this embodiment, the first input terminal of the error amplification module 103 is used to receive the output voltage Vout of the DC-DC converter 200; the input terminal of the ramp signal generation module 101 is used to receive the input voltage Vin of the DC-DC converter 200.

[0030] Based on this, for any sampling period, the working principle of each module in the conduction time control circuit 100 is as follows: The ramp signal generation module 101 is used to generate ramp signals based on the input voltage.

[0031] The peak sampling module 102 is used to acquire the peak voltage of the ramp signal in the current sampling period.

[0032] The error amplification module 103 is used to determine the error signal based on the peak voltage and the output voltage.

[0033] The conduction time generation module 104 is used to generate a status indication signal based on the error signal and the ramp signal.

[0034] The charging module 201 is used to adjust its own charging / discharging state according to the status indication signal so that the ramp signal generation module generates a ramp signal.

[0035] Based on this, the conduction time control circuit in this embodiment can change the peak voltage of the ramp signal in the next sampling period according to the charging module, that is, by the charging / discharging state of the charging module itself, thereby adjusting the on / off time of the switching transistor of the DC-DC converter.

[0036] Please continue to refer to this. Figure 2 For any sampling period, the charging module under the ramp signal generation module generates a ramp signal Ramp based on the input voltage Vin of the DC-DC converter and the initially set charging / discharging state. The peak sampling module obtains the peak voltage Ramp-peak of the ramp signal in the current sampling period and compares it with the output voltage Vout of the DC-DC converter. Then, it generates a corresponding error signal Vea based on the comparison result. Subsequently, the conduction time generation module generates a status indication signal Ramp-OK based on the corresponding error signal and the ramp signal in the current sampling period. The charging module adjusts its own charging / discharging state based on the status indication signal Ramp-OK, changes the peak voltage of the ramp signal in the next sampling period, and thus adjusts the on / off time of the switching transistor under the DC-DC converter.

[0037] In summary, this embodiment adds an error amplification module, which generates a signal that can improve the charging / discharging state of the charging module by comparing the peak voltage with the output voltage. This improves the peak voltage of the ramp signal cycle by cycle, reducing the complexity of the controller structure while improving the accuracy of the turn-on or turn-off time as the input and output voltages change.

[0038] It should be noted that in this embodiment, the status indication signal is used to characterize the required on-time or off-time of the switching transistor in the DC-DC converter. Furthermore, in this embodiment, the charging module can not only generate ramp signals, but also adjust its own charging / discharging state according to the aforementioned status indication signal, so as to generate ramp signals with different peak voltages corresponding to different charging / discharging states.

[0039] In this embodiment, the error amplification module includes at least two operating states; the error signal includes multiple error commands, and each operating state corresponds to one error command.

[0040] When the peak voltage of the ramp signal is greater than the output voltage in the current sampling period, the error amplification module 103 is in the first working state, which is used to send the first error command to the conduction time generation module 104, drive the conduction time generation module 104 to generate the first state command signal, adjust the charging / discharging state of the charging module 201, reduce the peak voltage of the ramp signal in the next sampling period, until the peak voltage is equal to the output voltage. And / or when the peak voltage of the ramp signal is less than the output voltage in the current sampling period, the error amplification module 103 is in the second working state, and is also used to send a second error command to the conduction time generation module 104, drive the conduction time generation module 104 to generate a second state command signal, adjust the charging / discharging state of the charging module 201, and increase the peak voltage of the ramp signal in the next sampling period until the peak voltage is equal to the output voltage.

[0041] This embodiment does not limit the implementation structure of the error amplification module. For one possible implementation, please refer to... Figure 3 , Figure 3 The diagram shows a block illustration of the conduction time generation module provided in this embodiment. In this embodiment, the error amplification module 103 can be a low-speed error amplifier 202. The first input terminal of the low-speed error amplifier 202 is connected to the output terminal of the DC-DC converter to receive the output voltage Vout of the DC-DC converter; the second input terminal is connected to the output terminal of the peak sampling module 102 to receive the peak voltage Ramp-peak of the ramp signal; and the output terminal is connected to the second input terminal of the conduction time generation module 104. This low-speed error amplifier amplifies the difference between the output voltage and the peak voltage to generate an error signal at the output terminal of the low-speed error amplifier.

[0042] In this embodiment, the error command under the error signal can be high or low level.

[0043] In this embodiment, if the peak voltage of the ramp signal in the current sampling period is greater than the output voltage, the error amplification module sends a high level to the conduction time generation module. At this time, the pulse width corresponding to the status indication signal Ramp_ok generated by the conduction time generation module is greater than the actual set conduction time or turn-off time. Based on this, the peak voltage of the ramp signal in the next sampling period can be reduced by adjusting the charging / discharging state of the charging module itself. Then, through cycle-by-cycle adjustment, the peak voltage of the ramp signal is made equal to the output voltage.

[0044] Similarly, if the peak voltage of the ramp signal in the current sampling period is less than the output voltage, the error amplification module sends a low level to the conduction time generation module. At this time, the pulse width of the status indication signal Ramp_ok generated by the conduction time generation module is less than the actual set conduction time or turn-off time. Based on this, the peak voltage of the ramp signal in the next sampling period can be increased by adjusting the charging / discharging state of the charging module itself. Then, through cycle-by-cycle adjustment, the peak voltage of the ramp signal can be made equal to the output voltage.

[0045] This embodiment does not limit the implementation structure of the charging module. For one possible implementation, please refer to... Figure 4 , Figure 4 The circuit schematic of the charging module provided in this embodiment is shown. The charging module 201 includes a charging capacitor C1 and a first switch Q1. The control terminal of the first switch Q1 is connected to the output terminal of the conduction time generation module 104 to receive a status indication signal. The first terminal of the first switch Q1 is connected to the first terminal of the charging capacitor C1. The first terminal of the charging capacitor C1 serves as the output terminal of the ramp signal generation module 101 and is connected to the input terminal of the peak sampling module 102 and the first input terminal of the conduction time generation module 104. The second terminals of the charging capacitor C1 and the second terminal of the first switch Q1 are both grounded. The charging module 201 is used to adjust the on / off state of the first switch Q1 and change the charging / discharging state of the charging capacitor C1 according to the status indication signal, such as the first status instruction signal or the second status instruction signal mentioned above.

[0046] Please refer to Figure 5 , Figure 5 The circuit schematic of the conduction time generation module provided in this embodiment is shown. In this embodiment, the conduction time generation module 104 includes a first comparator U1. The first terminal of the first comparator U1 is connected to the output terminal of the ramp signal generation module 101 to receive the ramp signal Ramp. The second terminal of the first comparator U1 is connected to the output terminal of the error amplification module 103 to receive the error signal Vea. The output terminal of the first comparator U1 is connected to the control terminal of the charging module 201.

[0047] In this embodiment, the first comparator U1 is used to compare the ramp signal Ramp and the error signal Vea to generate a status indication signal Ramp-OK at the output of the first comparator U1.

[0048] Please continue to refer to this. Figure 5In this embodiment, the conduction time generation module 104 further includes at least two cascaded logic inverters; when this embodiment includes a first logic inverter INV1 and a second logic inverter INV2, the output terminal of the first comparator U1 is connected to the input terminal of the first logic inverter INV1; the output terminal of the first logic inverter INV1 is connected to the input terminal of the second logic inverter INV2; and the output terminal of the second logic inverter INV2 is connected to the control terminal of the charging module 201.

[0049] Please continue to refer to this. Figure 5 The output of the first comparator U1 is also connected to the control terminal of the DC-DC converter 200 to feed back the status indication signal Ramp-OK generated by the first comparator based on the input voltage Vout and the ramp signal Ramp to the DC-DC converter 200, thereby adjusting the on and off time of the switching transistor in the DC-DC converter.

[0050] Please Figure 3 Based on, refer to Figure 6 , Figure 6 A block diagram of the conduction time control circuit provided in this embodiment is shown. The peak sampling module 102 includes a sample-and-hold circuit 203, the input of which is used to receive the ramp signal Ramp. The output of the sample-and-hold circuit 203 is connected to the second input of the error amplification module 103. In this embodiment, the sample-and-hold circuit 203 is used to acquire the peak voltage Ramp-peak of the ramp signal within one sampling period.

[0051] Based on this, this embodiment can reduce the complexity of the control device structure by using the sample-and-hold circuit 203 and the low-speed error amplifier 202, while adjusting the peak voltage of the ramp signal cycle by cycle, thereby improving the accuracy of the converter's turn-on time or turn-off time as the input voltage and output voltage change.

[0052] Please refer to Figure 7 , Figure 7 The diagram shows the structure of the ramp signal generation module provided in this embodiment. The ramp signal generation module 101 further includes a voltage conversion module 204, the output of which is connected to the charging module 201. The input of the voltage conversion module 204 is used to receive the input voltage from the DC-DC converter 200. The voltage conversion module 204 converts the input voltage into a current signal and uses this current signal to power the charging module 201.

[0053] Please Figure 7 Based on, refer to Figure 8 , Figure 8The circuit diagram of the conduction time control circuit provided in this embodiment is shown; the ramp signal generation module 101 also includes a current mirror module 206; the voltage conversion module 204 includes a second error amplifier U2, a second switch Q2, a first capacitor C2, and a first resistor R1; the first input terminal of the second error amplifier U2 is used to receive the input voltage; the second input terminal of the second error amplifier U2 is connected to the first terminal of the second switch Q2 and the first terminal of the first resistor R1; the output terminal of the second error amplifier U2 is connected to the first terminal of the first capacitor C2 and the control terminal of the second switch Q2; the second terminal of the second switch Q2 is connected to the first terminal of the current mirror module 206; the second terminal of the current mirror module 206 is connected to the first terminal of the charging module 201; the second terminal of the first resistor R1 and the second terminal of the first capacitor C2 are both grounded.

[0054] In this embodiment, the current mirror module 206 is used to generate current to power the charging module 201 based on the current signal provided by the voltage conversion module 204.

[0055] Please continue to refer to this. Figure 8 In this embodiment, the current mirror module 206 includes a first transistor M1 and a second transistor M2. The first terminal of the first transistor M1 is connected to the control terminal of the first transistor M1 and the control terminal of the second transistor M2. The second terminal of the first transistor M1 is connected to the second terminal of the second transistor M2, and the first terminal of the second transistor M2 is connected to the first terminal of the charging module 201.

[0056] To ensure the stability of the ramp signal generation module 101, please... Figure 7 Based on, refer to Figure 9 , Figure 9 The diagram shows the structure of the ramp signal generation module provided in this embodiment; the ramp signal generation module 101 also includes a voltage divider module 205, the first end of which is used to receive the input voltage Vin of the DC-DC converter 200; the second end of the voltage divider module 205 is connected to the input end of the voltage conversion module 204; and the third end of the voltage divider module 205 is grounded.

[0057] This embodiment does not limit the structure of the voltage divider module. In one possible implementation, the voltage divider module may include multiple resistors. Please refer to [reference needed]. Figure 10 , Figure 10 The circuit diagram of the conduction time control circuit provided in this embodiment is shown. In this embodiment, the voltage divider module 205 may include a second resistor R2 and a third resistor R3. The first end of the second resistor R2 is used to receive the input voltage Vin, and the second end of the second resistor R2 is connected to the first end of the second error amplifier U2 and the first end of the third resistor R3. The second end of the third resistor R3 is grounded.

[0058] In actual circuit structures, due to device characteristics, the offset voltage of the comparator module and the delay in the logic structure are inevitable. This can cause the toggle time of the status indicator signal Ramp_ok to be earlier or later than the time when the peak voltage value Ramp-peak reaches the output voltage Vout, thus interfering with the on / off time of the switching transistor in the DC-DC converter 200. Based on this, in Figure 10 Based on, refer to Figure 11 , Figure 11 The working timing of the conduction time control circuit in this embodiment is shown. When the peak voltage value Ramp-peak obtained by the sample-and-hold circuit 203 is greater than the output voltage Vout, the pulse width corresponding to the status indication signal Ramp_ok is greater than the actual set conduction time or turn-off time. In the next sampling cycle, the peak voltage value Ramp-peak can be reduced cycle by cycle through the error signal Vea generated by the low-speed error amplifier 202 until the peak voltage value Ramp-peak is equal to the output voltage Vout.

[0059] Similarly, when the peak voltage value Ramp-peak obtained by the sample-and-hold circuit 203 is less than the output voltage Vout, the pulse width corresponding to the status indication signal Ramp_ok is less than the actual set on or off time. In the next sampling cycle, the peak voltage value Ramp-peak can be increased cycle by cycle through the error signal Vea generated by the low-speed error amplifier 202 until the peak voltage value Ramp-peak is equal to the output voltage Vout.

[0060] When the peak voltage Ramp-peak equals the output voltage Vout, the voltage value of the error signal Vea should also equal the output voltage Vout. At this time, the status indicator signal Ramp_ok should toggle when the peak voltage Ramp reaches the output voltage Vout. The corresponding pulse width Ton calculation formula should be expressed as: Ton=C1*Vout / I1=C1*Vout / (K*Vin).

[0061] In the formula, I1 is the current value generated by the voltage conversion module; K is a positive integer.

[0062] This embodiment uses a sample-and-hold circuit to acquire the peak voltage value Ramp-peak of the ramp signal Ramp, and a low-speed error amplifier generates an error signal Vea based on the peak voltage value Ramp-peak and the output voltage Vout. Finally, the ramp signal Ramp and the error signal Vea are passed through a comparator to generate a new Ramp_ok signal, improving the peak voltage of the ramp signal cycle by cycle, thereby obtaining the turn-on time or turn-off time required by the DC-DC converter. Based on this, this embodiment can improve the accuracy of the turn-on time or turn-off time as the input and output voltages change, while reducing the complexity of the control device structure.

[0063] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0064] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0065] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A conduction time control circuit, applied to a switching conversion system, the switching conversion system including a DC-DC converter, characterized in that, The conduction time control circuit includes a ramp signal generation module, a peak sampling module, an error amplification module, and a conduction time generation module; the ramp signal generation module includes at least a charging module. The output terminal of the ramp signal generation module is connected to the first input terminal of the conduction time generation module and the input terminal of the peak sampling module; the output terminal of the peak sampling module is connected to the second input terminal of the error amplification module; the output terminal of the error amplification module is connected to the second input terminal of the conduction time generation module; the output terminal of the conduction time generation module is also connected to the control terminal of the charging module and the control terminal of the DC-DC converter; the first input terminal of the error amplification module is used to receive the output voltage of the DC-DC converter; the input terminal of the ramp signal generation module is used to receive the input voltage of the DC-DC converter. Specifically, for any sampling period, the ramp signal generation module is used to generate a ramp signal based on the input voltage; The peak sampling module is used to obtain the peak voltage of the ramp signal in the current sampling period; The error amplification module is used to determine the error signal based on the peak voltage and the output voltage; The conduction time generation module is used to generate a status indication signal based on the error signal and the ramp signal; The charging module is used to adjust its own charging / discharging state according to the status indication signal so that the ramp signal generation module generates a ramp signal.

2. The conduction time control circuit according to claim 1, characterized in that, The conduction time control circuit is also used to adjust the on / off time of the lower switching transistor of the DC-DC converter by changing the peak voltage of the ramp signal in the next sampling period according to the charging module.

3. The conduction time control circuit according to claim 1, characterized in that, The error amplification module includes at least two operating states; the error signal includes multiple error commands, with each operating state corresponding to one error command. When the peak voltage of the ramp signal is greater than the output voltage in the current sampling period, the error amplification module is in a first working state, used to send a first error command to the conduction time generation module, drive the conduction time generation module to generate a first state command signal, adjust the charging / discharging state of the charging module, reduce the peak voltage of the ramp signal in the next sampling period, until the peak voltage is equal to the output voltage; And / or when the peak voltage of the ramp signal is less than the output voltage in the current sampling period, the error amplification module is in a second working state, and is also used to send a second error command to the conduction time generation module, drive the conduction time generation module to generate a second state command signal, adjust the charging / discharging state of the charging module, and increase the peak voltage of the ramp signal in the next sampling period until the peak voltage is equal to the output voltage.

4. The conduction time control circuit according to claim 1 or 2, characterized in that, The charging module includes a charging capacitor and a first switching transistor. The control terminal of the first switching transistor is connected to the output terminal of the conduction time generation module to receive the status indication signal. The first terminal of the first switching transistor is connected to the first terminal of the charging capacitor. The first terminal of the charging capacitor serves as the output terminal of the ramp signal generation module and is connected to the first input terminal of the conduction time generation module and the input terminal of the peak sampling module. The second terminal of the charging capacitor and the second terminal of the first switching transistor are both grounded. The charging module is used to adjust the on / off state of the first switch transistor according to the status indication signal, thereby changing the charging / discharging state of the charging capacitor.

5. The conduction time control circuit according to any one of claims 1 to 3, characterized in that, The error amplification module includes a low-speed error amplifier; the first input terminal of the low-speed error amplifier is connected to the output terminal of the DC-DC converter to receive the output voltage of the DC-DC converter, and the second input terminal of the low-speed error amplifier is connected to the output terminal of the peak sampling module to receive the peak voltage of the ramp signal; the output terminal of the low-speed error amplifier is connected to the second input terminal of the conduction time generation module. The low-speed error amplifier is used to amplify the difference between the output voltage and the peak voltage to generate an error signal at the output of the low-speed error amplifier.

6. The conduction time control circuit according to any one of claims 1 to 3, characterized in that, The conduction time generation module includes a first comparator; a first terminal of the first comparator is connected to the output terminal of the ramp signal generation module to receive the ramp signal; a second terminal of the first comparator is connected to the output terminal of the error amplification module to receive the error signal; and the output terminal of the first comparator is connected to the control terminal of the charging module. The first comparator is used to compare the ramp signal and the error signal to generate the status indication signal at the output of the first comparator.

7. The conduction time control circuit according to any one of claims 1 to 3, characterized in that, The peak sampling module includes a sample-and-hold circuit, the input of which is used to receive the ramp signal; the output of which is connected to the second input of the error amplification module. The sample-and-hold circuit is used to acquire the peak voltage of the ramp signal within one sampling period.

8. The conduction time control circuit according to any one of claims 1 to 3, characterized in that, The ramp signal generation module further includes a voltage conversion module, the output of which is connected to the charging module; the input of the voltage conversion module is used to receive the input voltage of the DC-DC converter; the first end of the charging module serves as the output of the ramp signal generation module and is connected to the first input of the conduction time generation module and the input of the peak sampling module; the control end of the charging module is also used to receive the status indication signal. The voltage conversion module is used to convert the input voltage into a current signal and to supply power to the charging module through the current signal.

9. The conduction time control circuit according to claim 8, characterized in that, The ramp signal generation module further includes a current mirror module; the voltage conversion module includes a second error amplifier, a second switching transistor, a first capacitor, and a first resistor; the first input terminal of the second error amplifier receives the input voltage; the second input terminal of the second error amplifier is connected to the first terminal of the second switching transistor and the first terminal of the first resistor; the output terminal of the second error amplifier is connected to the first terminal of the first capacitor and the control terminal of the second switching transistor; the second terminal of the second switching transistor is connected to the first terminal of the current mirror module; the second terminal of the current mirror module is connected to the first terminal of the charging module; the second terminals of the first resistor and the second terminals of the first capacitor are both grounded; The current mirror module is used to generate current to power the charging module based on the current signal provided by the voltage conversion module.

10. A switching conversion system, characterized in that, It includes a DC-DC converter and the on-time control circuit according to any one of claims 1 to 9.

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