On-time generation circuit and DC-DC converter

Abstract

This application provides a conduction time generation circuit and a DC-DC converter, relating to the field of analog integrated circuit technology. The conduction time generation circuit includes: a voltage detection module, a reference voltage generation module, a comparator, and a latch; the input terminal of the voltage detection module is connected to either the input or output terminal of the DC-DC converter, and the output terminal of the voltage detection module is connected to the positive input terminal of the comparator; the voltage input terminal of the reference voltage generation module acquires multiple voltage values ​​from the DC-DC converter, the current input terminal of the reference voltage generation module acquires the inductor current of the DC-DC converter, and the output terminal is connected to the negative input terminal of the comparator; the output terminal of the comparator is connected to the reset terminal of the latch; the set terminal of the latch receives a pulse control signal, and the output terminal of the latch is connected to the control terminal of the DC-DC converter's main control module to control the main control module of the DC-DC converter. This application can achieve stable switching frequency by adaptively adjusting the conduction time.

Description

Technical Field

[0001] This application relates to the field of analog integrated circuit technology, and more specifically, to an on-time generation circuit and a DC-DC converter. Background Technology

[0002] With the rapid development of the Internet of Things, AI technology, and new energy vehicles, as well as the increasing demand for consumer electronics products such as fast chargers, the integrated circuit industry is becoming increasingly profitable.

[0003] Power management chips are one of the largest types of chips in the target integrated circuit market. Among them, DC-DC converter chips are experiencing a continuous expansion in market demand due to their advantages such as flexible application environment and high conversion efficiency.

[0004] However, in existing DC-DC converter circuits, when the main conductor is controlled to turn on by a constant on-time, the converter's switching frequency is affected by changes in the input and output voltages, resulting in a non-constant switching frequency. Furthermore, in practical applications, the duty cycle is not only related to the input and output voltages but also affected by the load current, causing the switching frequency to shift with changes in the load. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of the prior art by providing a conduction time generation circuit and a DC-DC converter, so as to achieve stable switching frequency through adaptive adjustment of conduction time.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, embodiments of this application provide an on-time generation circuit applied to a DC-DC converter, the on-time generation circuit comprising: a voltage detection module, a reference voltage generation module, a comparator, and a latch;

[0008] The input terminal of the voltage detection module is used to connect to the input or output terminal of the DC-DC converter to generate a detection voltage based on the input or output voltage of the DC-DC converter. The output terminal of the voltage detection module is connected to the positive input terminal of the comparator.

[0009] The voltage input terminal of the reference voltage generation module is used to obtain multiple voltage values ​​of the DC-DC converter, and the current input terminal of the reference voltage generation module is used to obtain the inductor current of the DC-DC converter, so as to generate a reference voltage based on the multiple voltage values ​​and inductor current of the DC-DC converter. The output terminal of the reference voltage generation module is connected to the negative input terminal of the comparator.

[0010] The output of the comparator is connected to the reset terminal of the latch to provide an on-time signal to the latch based on the comparison result of the detected voltage and the reference voltage.

[0011] The set terminal of the latch is used to receive a pulse control signal, and the output terminal of the latch is used to connect to the control terminal of the main body of the DC-DC converter, so as to control the main body of the DC-DC converter during the conduction time according to the conduction time signal.

[0012] Optionally, the voltage detection module includes: a first voltage-to-current conversion module and a charging capacitor;

[0013] The input terminal of the first voltage-to-current conversion module serves as the input terminal of the voltage detection module, and the output terminal of the first voltage-to-current conversion module is connected to one end of the charging capacitor as the output terminal of the voltage detection module, while the other end of the charging capacitor is grounded.

[0014] Optionally, the voltage detection module further includes: an inverter and a first power transistor;

[0015] The input terminal of the inverter is connected to the output terminal of the latch, the output terminal of the inverter is connected to the gate of the first power transistor, the drain of the first power transistor is connected to one end of the charging capacitor, and the source of the first power transistor is connected to the other end of the charging capacitor.

[0016] Optionally, the reference voltage generation module includes: a second voltage-to-current conversion module, a resistance module, a current sensing module, and an impedance detection module;

[0017] The input terminal of the second voltage-to-current conversion module and the voltage input terminal of the impedance detection module serve as the voltage input terminal of the reference voltage generation module. The output terminal of the second voltage-to-current conversion module is connected to the first terminal of the resistor module and serves as the output terminal of the reference voltage generation module.

[0018] The input terminal of the current sensing module serves as the current input terminal of the reference voltage generation module, and the output terminal of the current sensing module is connected to the second terminal of the resistor module and the current input terminal of the impedance detection module.

[0019] The impedance detection module is also used to acquire the control signal of the slave transistor of the DC-DC converter and the equivalent resistance value of the inductor of the DC-DC converter. The output terminal of the impedance detection module is connected to the control terminal of the resistor module to adjust the voltage division ratio of the resistor module.

[0020] Optionally, the resistor module includes: a fixed resistor unit and an adjustable resistor unit;

[0021] One end of the fixed resistor unit serves as the first end of the resistor module, the other end of the fixed resistor unit is connected to one end of the adjustable resistor unit as the second end of the resistor module, the other end of the adjustable resistor unit is grounded, and the control end of the adjustable resistor unit serves as the control end of the resistor module.

[0022] Optionally, the current sensing module includes: a second power transistor, a third power transistor, and a current operational amplifier;

[0023] The gates of the second power transistor and the third power transistor are connected to the gate of the main power transistor of the DC-DC converter.

[0024] One of the drain and source terminals of the second power transistor is connected to one of the drain and source terminals of the slave transistor of the DC-DC converter, and the other of the drain and source terminals of the second power transistor is connected to the first input terminal of the current operational amplifier.

[0025] One of the drain and source terminals of the third power transistor is connected to the other of the drain and source terminals of the slave transistor of the DC-DC converter, and the other of the drain and source terminals of the third power transistor is connected to the first input terminal of the current operational amplifier.

[0026] The output terminal of the current operational amplifier serves as the output terminal of the current sensing module.

[0027] Optionally, the impedance detection module includes: an impedance calculation unit and an adder;

[0028] The voltage input terminal of the impedance calculation unit serves as the voltage input terminal of the impedance detection module, and the current input terminal of the impedance calculation unit serves as the current input terminal of the impedance detection module. The control terminal of the impedance calculation unit receives the control signal from the slave transistor of the DC-DC converter. The output terminal of the impedance calculation unit is connected to one input terminal of the adder, and the other input terminal of the adder obtains the inductance equivalent resistance value of the DC-DC converter. The output terminal of the adder serves as the output terminal of the impedance detection module.

[0029] Optionally, if the DC-DC converter is a boost converter, the input terminal of the voltage detection module is connected to the output terminal of the DC-DC converter, the input terminal of the second voltage-to-current conversion module is connected to the input and output terminals of the boost converter to obtain the input voltage and output voltage of the boost converter, and the voltage input terminal of the impedance detection module is connected to the output terminal of the boost converter and the connection point of the main and slave tubes of the boost converter to obtain the output voltage and switching voltage of the boost converter.

[0030] Optionally, if the DC-DC converter is a buck converter, the input terminal of the voltage detection module is connected to the input terminal of the DC-DC converter, the input terminal of the second voltage-to-current conversion module is connected to the output terminal of the buck converter to obtain the output voltage of the buck converter, and the voltage input terminal of the impedance detection module is connected to the connection point of the main and slave tubes of the buck converter and ground to obtain the switching voltage and ground voltage of the buck converter.

[0031] Secondly, embodiments of this application also provide a DC-DC converter, which includes a DC-DC conversion circuit and an on-time generation circuit. The output terminal of the on-time generation circuit is used to connect to the control terminal of the main body of the DC-DC converter. The on-time generation circuit is the circuit described in any of the first aspects.

[0032] The beneficial effects of this application are:

[0033] The conduction time generation circuit and DC-DC converter provided in this application generate a detection voltage related to the input voltage or output voltage through a voltage detection module, and generate reference voltages related to multiple voltages and inductor currents of the DC-DC converter through a reference voltage generation module. By comparing the detection voltage and the reference voltage, the output of the latch is controlled according to the comparison result. The flipping of the comparison result determines the conduction time. That is, this scheme generates a conduction time that varies with the input voltage, output voltage and load, so as to compensate for the problem of switching frequency deviation caused by the change of duty cycle due to the influence of input voltage, output voltage and load. This makes the switching frequency unaffected by the input voltage, output voltage and inductor current, and realizes frequency stabilization of the converter. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, 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 this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a topology diagram of a traditional constant on-time boost DC-DC converter;

[0036] Figure 2 The schematic diagram of an existing conduction time generation circuit;

[0037] Figure 3 The waveform diagram of the existing DC-DC converter is shown.

[0038] Figure 4 A basic block diagram of the conduction time generation circuit provided in the embodiments of this application;

[0039] Figure 5 This is a topology diagram of a traditional BUCK-type DC-DC converter;

[0040] Figure 6 A schematic diagram of the conduction time generation circuit provided in the embodiments of this application. Figure 1 ;

[0041] Figure 7 This is a circuit for generating the on-time of a buck converter.

[0042] Figure 8 A schematic diagram of the current sensing module of the boost converter provided in an embodiment of this application;

[0043] Figure 9 A schematic diagram of the current sensing module of the buck converter provided in the embodiments of this application;

[0044] Figure 10 This is a schematic diagram of the impedance detection module provided in an embodiment of this application. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0046] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0047] Furthermore, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Additionally, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0049] Figure 1 The topology diagram of a traditional constant on-time boost DC-DC converter is shown below. Figure 1 As shown, under ideal conditions, without considering non-ideal factors such as the on-resistance of the power transistor and the equivalent series resistance of the capacitor and inductor, the input voltage V of the constant on-time (COT) controlled boost DC-DC converter is... IN and output voltage V OUT The relationship between them is:

[0050]

[0051]

[0052] in, t on Let M1 be the conduction time of the main converter, and T be the duty cycle of the converter. Therefore, the duty cycle D can be expressed as:

[0053]

[0054] The loop generates a constant on-time. t on This controls the conduction of the main control M1, which in turn affects the switching frequency of the converter. It is not constant and will change with the input and output voltage, which is not conducive to the design of subsequent filter circuits.

[0055] Adaptive On-Time (AOT) control optimizes the current on-time based on the current on-time (COT) control. t on It adapts to changes in output and output voltage, and the switching frequency remains constant in Continuous Conduction Mode (CCM).

[0056] In practical applications, especially with a wide load range, the on-resistance of the main tube M1 and the slave tube M2, as well as the direct current resistance (DCR) of the inductor, have a significant impact on the duty cycle. Considering non-ideal factors, the duty cycle D is not only related to V... IN V OUT It is related to, and also affected by, load current. I LOAD This has an impact. Therefore, the switching frequency of the AOT loop will deviate to a certain extent with changes in load; the greater the load, the more pronounced the deviation. The same applies to BUCK-type DC-DC converters.

[0057] Figure 2 The schematic diagram is for an existing conduction time generation circuit. Figure 3 For the operating waveforms of existing DC-DC converters, such as Figure 2 As shown, after the timing starts, a constant current is used. I ref When a constant capacitor C is charged, when the capacitor voltage... V c Achieve a fixed reference voltage V ref Then, the comparator reverses, the timing ends, and the working waveform is as follows: Figure 3 As shown. The charging time of the capacitor is the same as the conduction time of the main conductor. t on :

[0058]

[0059] From the formula, we can see that... t on It is related to the input voltage V IN Output voltage V OUT The switching frequency of the converter is not fixed because it is an irrelevant constant.

[0060] Furthermore, in practical applications, the duty cycle approximation is related to the input and output voltages and is also affected by the load current, causing the switching frequency to shift with changes in the load.

[0061] Based on the problems existing in the prior art, this application proposes to provide a conduction time generation circuit and a DC-DC converter, which generates a conduction time that varies with the input voltage, output voltage and load to control the main control, so as to compensate for the problem of switching frequency deviation caused by duty cycle changes and realize frequency stabilization of the converter.

[0062] Figure 4 The basic block diagram of the conduction time generation circuit provided in the embodiments of this application is as follows: Figure 4 As shown, the conduction time generation circuit may include: a voltage detection module 10, a reference voltage generation module 20, a comparator 30, and a latch 40.

[0063] The input terminal of the voltage detection module 10 is used to connect to the input or output terminal of the DC-DC converter to generate a detection voltage based on the input or output voltage of the DC-DC converter. The output terminal of the voltage detection module 10 is connected to the positive input terminal of the comparator 30.

[0064] The voltage input terminal of the reference voltage generation module 20 is used to obtain multiple voltage values ​​of the DC-DC converter, and the current input terminal of the reference voltage generation module 20 is used to obtain the inductor current of the DC-DC converter, so as to generate a reference voltage based on the multiple voltage values ​​and inductor current of the DC-DC converter. The output terminal of the reference voltage generation module 20 is connected to the negative input terminal of the comparator 30.

[0065] The output of comparator 30 is connected to the reset terminal of latch 40 to provide an on-time signal to latch 40 based on the comparison result of the detected voltage and the reference voltage.

[0066] The set terminal of latch 40 is used to receive pulse control signals, and the output terminal of latch 40 is connected to the control terminal of the main body of the DC-DC converter to control the main body of the DC-DC converter during the conduction time according to the conduction time signal.

[0067] In this embodiment, if the DC-DC converter is a boost converter, the input terminal of the voltage detection module 10 is connected to the output terminal of the boost converter to obtain the output voltage of the boost converter, and a detection voltage is generated based on the output voltage of the boost converter. When the main tube of the boost converter is turned on, the detection voltage gradually increases.

[0068] The voltage input terminal of the reference voltage generation module 20 is connected to the input terminal, output terminal, main tube and slave tube connection points of the boost converter, respectively, to obtain the input voltage, output voltage and switching voltage of the boost converter. The current input terminal of the reference voltage generation module 20 is connected to the connection points of the main tube and slave tube of the boost converter and the output terminal of the boost converter, and is used to generate the inductor current component based on the inductor current of the boost converter. The reference voltage generation module 20 generates a reference voltage based on the input voltage, output voltage, switching voltage and inductor current component of the boost converter.

[0069] If the DC-DC converter is a buck converter, the input terminal of the voltage detection module 10 is connected to the input terminal of the buck converter to obtain the input voltage of the buck converter, and generates a detection voltage based on the input voltage of the buck converter. When the main tube of the buck converter is turned on, the detection voltage gradually increases.

[0070] The voltage input terminal of the reference voltage generation module 20 is connected to the output terminal of the buck converter, the connection point of the main and slave tubes, and ground, respectively, to obtain the output voltage, switching voltage, and ground voltage of the buck converter. The current input terminal of the reference voltage generation module 20 is connected to the connection point of the main and slave tubes of the buck converter and the ground of the buck converter, and is used to generate the inductor current component based on the inductor current of the buck converter. The reference voltage generation module 20 generates a reference voltage based on the output voltage, switching voltage, ground voltage, and inductor current component of the buck converter.

[0071] Comparator 30 compares the detected voltage with the reference voltage. When the detected voltage is less than the reference voltage, the output of comparator 30 is low level 0. Latch 40 outputs a control signal for the main body of the DC-DC converter according to the pulse control signal received at the set terminal S. When the pulse control signal is high level 1, the output terminal Q of latch 40 outputs a high level 1 conduction control signal. When the pulse control signal is low level 0, the output terminal Q of latch 40 maintains the current state, that is, continues to output a high level 1 conduction control signal.

[0072] When the detected voltage reaches the reference voltage, the output of comparator 30 flips to a high level 1, the reset terminal R of latch 40 is reset based on the high level 1, and the output terminal Q of latch 40 is forced to output a low level 0 shutdown control signal.

[0073] In some embodiments, latch 40 may be a NOR-type SR latch.

[0074] As can be seen, during the process where the voltage detection module 10 generates a detection voltage based on the input voltage or output voltage of the DC-DC converter, and the reference voltage generation module 20 outputs a reference voltage based on the voltage values ​​and inductor current of multiple detection points of the DC-DC converter, the magnitudes of the detection voltage and reference voltage are determined by multiple parameters, including the input voltage, output voltage, and inductor current of the DC-DC converter. The time for the detection voltage to rise from less than the reference voltage to reach the reference voltage is the conduction time of the main body of the DC-DC converter. In other words, the conduction time of the main body of the DC-DC converter in this scheme is related to the input voltage, output voltage, and inductor current of the DC-DC converter.

[0075] Considering non-ideal factors such as the on-resistance of the main and slave transistors of the DC-DC converter and the shoot-through current of the inductor, the duty cycle of the main transistor of the DC-DC converter can be determined based on the ampere-second balance. It is also related to the input voltage, output voltage and inductor current of the DC-DC converter.

[0076] By designing reasonable parameters for the reference voltage generation module, it can be ensured that the operating frequency is independent of the input voltage, output voltage, and inductor current, and is a constant unaffected by these factors.

[0077] It should be noted that, as Figure 1 As shown, in a BOOST type DC-DC converter, the main transistor M1 is a power transistor connected between inductor L and ground, and the slave transistor M2 is a power transistor connected between inductor L and output terminal OUT.

[0078] Figure 5 The topology diagram of a traditional BUCK-type DC-DC converter is shown below. Figure 5As shown, in a BUCK-type DC-DC converter, the main transistor M1 is a power transistor connected between the input terminal IN and the inductor L, and the slave transistor M2 is a power transistor connected between the inductor L and ground.

[0079] The conduction time generation circuit provided in the above embodiment generates a detection voltage related to the input voltage or output voltage through a voltage detection module, and generates a reference voltage related to multiple voltages and inductor currents of the DC-DC converter through a reference voltage generation module. By comparing the detection voltage and the reference voltage, the output of the latch is controlled according to the comparison result. The flipping of the comparison result determines the conduction time. That is, this scheme generates a conduction time that varies with the input voltage, output voltage and load, so as to compensate for the problem of switching frequency deviation caused by the change of duty cycle due to the influence of input voltage, output voltage and load. This makes the switching frequency unaffected by the input voltage, output voltage and inductor current, and realizes frequency stabilization of the converter.

[0080] The following describes the specific implementation of the conduction time generation circuit for boost converters and buck converters with reference to the embodiments.

[0081] Figure 6 A schematic diagram of the conduction time generation circuit provided in the embodiments of this application. Figure 1 , Figure 7 A schematic diagram of the conduction time generation circuit provided in the embodiments of this application. Figure 2 ,like Figure 6 and Figure 7 As shown, the voltage detection module 10 may include: a first voltage-to-current conversion module 11 and a charging capacitor C.

[0082] The input terminal of the first voltage-to-current conversion module 11 serves as the input terminal of the voltage detection module 10. The output terminal of the first voltage-to-current conversion module 11 is connected to one end of the charging capacitor C as the output terminal of the voltage detection module 10, and the other end of the charging capacitor C is grounded.

[0083] In this embodiment, Figure 6 For use in the conduction time generation circuit of a boost converter, such as Figure 6 As shown, the input terminal of the first voltage-to-current conversion module 11 is connected to the output terminal of the boost converter to obtain the output voltage V of the boost converter. OUT and output voltage V OUT Convert to constant current I ref When charging capacitor C, the voltage across capacitor C is... V c It continues to increase in size during the charging process.

[0084] The equivalent resistance of the first voltage-to-current conversion module 11 is: R 1. Constant currentI ref = V OUT / R 1.

[0085] Figure 7 For use in the conduction time generation circuit of a buck converter, such as Figure 7 As shown, the input terminal of the first voltage-to-current conversion module 11 is connected to the input terminal of the buck converter, and is used to obtain the input voltage V of the buck converter. IN and input voltage V IN Convert to constant current I ref When charging capacitor C, the voltage across capacitor C is... V c It continues to increase in size during the charging process.

[0086] The equivalent resistance of the first voltage-to-current conversion module 11 is: R 1. Constant current I ref = V IN / R 1.

[0087] In some embodiments, the first voltage-to-current conversion module 11 may employ a clamping operational amplifier and a load. R 1. Based on the virtual short and virtual open principle of the clamping operational amplifier, voltage-to-current conversion is achieved.

[0088] In some embodiments, such as Figure 6 and Figure 7 As shown, the voltage detection module 10 may also include an inverter NOT and a first power transistor M3.

[0089] The input of inverter NOT is connected to the output of latch 40, the output of inverter NOT is connected to the gate of first power transistor M3, the drain of first power transistor M3 is connected to one end of charging capacitor C, and the source of first power transistor M3 is connected to the other end of charging capacitor C1.

[0090] In this embodiment, a constant current is used. I ref When charging capacitor C, the voltage across capacitor C is... V c Less than the reference voltage V ref At this time, all the main components of the DC-DC converter are in the ON state, and the voltage across the charging capacitor C is... V c Reaching the reference voltage V refWhen the DC-DC converter is turned off, the charging time of the charging capacitor C determines the conduction time of the DC-DC converter's main conductor.

[0091] Since the main circuit of the DC-DC converter is periodically turned on, the charging capacitor C needs to be periodically charged. During the charging process of the charging capacitor C, the control signal MSON output by latch 40 for the main circuit is a high-level (1) turn-on control signal, and the capacitor voltage of the charging capacitor C is... V c Reaching the reference voltage V ref When the latch 40 outputs a low-level (0) control signal MSON for the main controller, it is a shutdown control signal. At this time, the charging capacitor C needs to be discharged so that it can be recharged in the next cycle.

[0092] Therefore, when latch 40 outputs a high level 1, it is inverted to a low level 0 by inverter NOT, causing the first power transistor M3 to turn off and the charging capacitor C to continue charging. When latch 40 outputs a low level 0, it is inverted to a high level by inverter NOT, controlling the first power transistor M3 to turn on and causing the charging capacitor C to discharge.

[0093] In one possible implementation, such as Figure 6 and Figure 7 As shown, the reference voltage generation module 20 includes: a second voltage-to-current conversion module 21, a resistance module 22, a current sensing module 23, and an impedance detection module 24.

[0094] The input terminal of the second voltage-to-current conversion module 21 and the voltage input terminal of the impedance detection module 24 serve as the voltage input terminals of the reference voltage generation module 20. The output terminal of the second voltage-to-current conversion module 21 is connected to the first terminal of the resistor module 22 and serves as the output terminal of the reference voltage generation module 20.

[0095] The input terminal of the current sensing module 23 serves as the current input terminal of the reference voltage generation module 20, and the output terminal of the current sensing module 23 is connected to the second terminal of the resistor module 22 and the current input terminal of the impedance detection module 24.

[0096] The impedance detection module 24 is also used to obtain the control signal SSON of the slave tube of the DC-DC converter and the equivalent resistance value of the inductor of the DC-DC converter. The output terminal of the impedance detection module 24 is connected to the control terminal of the resistor module 22 to adjust the voltage division ratio of the resistor module 22.

[0097] In this embodiment, as Figure 6 and Figure 7 As shown, the current sensing module 23 acquires the inductor current of the boost converter or buck converter, and calculates the current based on the average value of the inductor current of the boost converter or buck converter. Generate inductor current component Where K is the sampling ratio of the inductor current of the current sensing module 23.

[0098] like Figure 6 As shown, for the boost converter, the input terminal of the second voltage-to-current conversion module 21 is connected to the input terminal and the output terminal of the boost converter, respectively, to obtain the input voltage V of the boost converter. IN and output voltage V OUT According to the input voltage V of the boost converter IN and output voltage V OUT Generate the current components corresponding to the input and output voltages.

[0099] The equivalent resistance of the second voltage-to-current conversion module 21 is: R 2. The current component is .

[0100] The impedance detection module 24 uses the voltage difference between the switching voltage and the output voltage of the boost converter, combined with the inductor current component output by the current sensing module 23, to detect the voltage difference. Determine the on-resistance R of tube M2. ON2 According to the on-resistance R of tube M2 ON2 The equivalent resistance R of the inductor in the boost converter DCR Determine the voltage division ratio β of the resistor.

[0101] The resistor module 22 adjusts the voltage division value according to the resistor voltage division ratio β, and adjusts the current component corresponding to the input and output voltage output by the second voltage-to-current conversion module 21, the total resistance of the resistor module 22, and the inductor current component output by the current sensing module 23. Calculate the reference voltage using the voltage divider resistance value of resistor module 22. V ref .

[0102] like Figure 7 As shown, for the buck converter, the input terminal of the second voltage-to-current conversion module 21 is connected to the output terminal of the buck converter to obtain the output voltage V of the buck converter. OUT According to the output voltage V of the buck converter OUT The current component that generates the output voltage.

[0103] The equivalent resistance of the second voltage-to-current conversion module 21 is R2, and the current component is... .

[0104] The impedance detection module 24 uses the voltage difference between the switching voltage of the buck converter and the ground voltage, combined with the inductor current component output by the current sensing module 23, to detect the voltage difference. Determine the on-resistance R of tube M2.ON2 According to the on-resistance R of tube M2 ON2 The equivalent resistance R of the inductor in the buck converter DCR Determine the voltage division ratio β of the resistor.

[0105] The resistor module 22 adjusts the voltage division value according to the resistor voltage division ratio β, and adjusts the current component of the output voltage output by the second voltage-to-current conversion module 21, the total resistance of the resistor module 22, and the inductor current component output by the current sensing module 23. Calculate the reference voltage using the voltage divider resistance value of resistor module 22. V ref .

[0106] In some embodiments, such as Figure 6 and Figure 7 As shown, the resistor module 22 includes a fixed resistor unit 221 and an adjustable resistor unit 222.

[0107] One end of the fixed resistor unit 221 serves as the first end of the resistor module 22, and the other end of the fixed resistor unit 221 is connected to one end of the adjustable resistor unit 222, which serves as the second end of the resistor module 22. The other end of the adjustable resistor unit 222 is grounded, and the control terminal of the adjustable resistor unit 222 serves as the control terminal of the resistor module 22.

[0108] In this embodiment, the resistance value of the fixed resistor unit 221 and the resistance value of the adjustable resistor unit 222 constitute the total resistance value R3 of the resistor module 22. The voltage division ratio β is used to adjust the resistance value of the adjustable resistor unit 222, and the resistance value of the adjustable resistor unit 222 is β*R3.

[0109] In one possible implementation, the current sensing module 23 includes a second power transistor M4, a third power transistor M5, and a current operational amplifier 231.

[0110] One of the drain and source terminals of the second power transistor M4 is connected to one of the drain and source terminals of the slave transistor M2 of the DC-DC converter, and the other terminal of the drain and source terminal of the second power transistor M4 is connected to the first input terminal of the current operational amplifier 231.

[0111] One of the drain and source terminals of the third power transistor M5 is connected to the other of the drain and source terminals of the slave transistor M2 of the DC-DC converter, and the other of the drain and source terminals of the third power transistor M5 is connected to the first input terminal of the current operational amplifier 231; the output terminal of the current operational amplifier 231 serves as the output terminal of the current sensing module 23.

[0112] In this embodiment, Figure 8 This application provides a schematic diagram of a current sensing module for a boost converter, applicable to a boost converter, such as... Figure 8As shown, one terminal of the drain-source junction of the second power transistor M4 in the current sensing module 23 is connected to the connection point SW between the main transistor M1 and the slave transistor M2 of the boost converter, and the other terminal is connected to the current operational amplifier 231; one terminal of the drain-source junction of the third power transistor M5 is connected to the output terminal OUT of the boost converter, and the other terminal is connected to the current operational amplifier 231. The gates of the second power transistor M4 and the third power transistor M5 are connected to the gate of the slave transistor M2.

[0113] The size ratio of the slave transistor M2, the second power transistor M4, and the third power transistor M5 is K:1:1, to collect the on-current I when the slave transistor M2 of the boost converter is turned on. L Based on the average inductor current of the boost converter Generate inductor current component .

[0114] Figure 9 This is a schematic diagram of the current sensing module of the buck converter provided in the embodiments of this application, applied to a buck converter, such as... Figure 9 As shown, one terminal of the drain-source junction of the second power transistor M4 in the current sensing module 23 is connected to the connection point SW between the main transistor M1 and the slave transistor M2 of the buck converter, and the other terminal is connected to the current operational amplifier 231; one terminal of the drain-source junction of the third power transistor M5 is connected to the ground of the buck converter, and the other terminal is connected to the current operational amplifier 231. The gates of the second power transistor M4 and the third power transistor M5 are connected to the gate of the slave transistor M2.

[0115] The size ratio of the slave transistor M2, the second power transistor M4, and the third power transistor M5 is K:1:1, to collect the on-current I when the slave transistor M2 of the buck converter is turned on. L Based on the average inductor current of the buck converter Generate inductor current component .

[0116] In one possible implementation, Figure 10 This is a schematic diagram of the impedance detection module provided in an embodiment of this application, as shown below. Figure 10 As shown, the impedance detection module 24 includes an impedance calculation unit 241 and an adder 242.

[0117] The voltage input terminal of the impedance calculation unit 241 serves as the voltage input terminal of the impedance detection module 24, and the current input terminal of the impedance calculation unit 241 serves as the current input terminal of the impedance detection module 24. The control terminal of the impedance calculation unit 241 receives the control signal from the slave transistor M2 of the DC-DC converter. The output terminal of the impedance calculation unit 241 is connected to one input terminal of the adder 242. The other input terminal of the adder 242 obtains the equivalent resistance value of the inductor of the DC-DC converter. The output terminal of the adder 242 serves as the output terminal of the impedance detection module 24.

[0118] In this embodiment, for the boost converter, the impedance calculation unit 241 calculates the impedance based on the switching voltage V of the boost converter. SW Output voltage V OUT and inductor current component Calculate the on-resistance R of the slave transistor M2 in the boost converter. ON2 , Adder 242 is based on the on-resistance R ON2 The equivalent resistance R of the inductor in the boost converter DCR Calculate the voltage division ratio β of the resistor.

[0119] For the buck converter, the impedance calculation unit 241 calculates the switching voltage V of the buck converter. SW Grounding voltage V GND and inductor current component Calculate the on-resistance R of the slave transistor M2 in the buck converter. ON2 , Adder 242 is based on the on-resistance R ON2 The equivalent resistance R of the inductor in the buck converter DCR Calculate the voltage division ratio β of the resistor.

[0120] The working principle of the conduction time generation circuits applied to boost converters and buck converters will be explained below.

[0121] like Figure 6 As shown, for a boost converter, considering the on-resistance of the main transistor M1 and the slave transistor M2, as well as non-ideal factors such as the inductor DCR, when the boost converter is operating in steady state, according to the ampere-second balance, we can obtain:

[0122]

[0123] in, For the inductor current, which varies in real time, the increment and decrement of the inductor current are equal within one period T, that is:

[0124] Where D is the duty cycle and T is the period, we can simplify to get:

[0125]

[0126] in, I L,AVG R is the average value of the inductor current. ON1 R ON2 These are the on-resistances of the main tube M1 and the slave tube M2, respectively, R DCR This represents the DC resistance of the inductor. Typically, the on-resistance of a power transistor is in the mΩ range; therefore, the second term in the denominator of the duty cycle D is related to V. OUTCompared to what can be ignored, it can also be made possible through design. To eliminate this, namely:

[0127]

[0128] like Figure 6 As shown, the reference voltage of the comparator in the circuit is generated during the conduction time. V ref Add inductor current component Where K is the inductor current sampling ratio. The reference voltage expression is:

[0129]

[0130] Substituting into the conduction time calculation formula, we get:

[0131]

[0132] Where β is the voltage division ratio of the resistors. In circuit design, choosing appropriate parameter values ​​ensures... This ensures the operating frequency. That is, the operating frequency is a constant that is independent of the application environment.

[0133] As can be seen from the formula, the power originates from the on-resistance R of transistor M2. ON2 The equivalent series resistance R of the inductor DCR This determines the value of β. R ON2 As the power supply voltage changes, R DCR The value of the external inductor is also a variable. Therefore, an impedance detection circuit is integrated inside the boost converter to sample V when transistor M2 is turned on. SW V OUT voltage difference and inductor current I L This allows us to obtain impedance-related information and adjust the voltage division ratio β of the resistor module.

[0134] like Figure 7 As shown, for a buck converter, considering the on-resistance of the main transistor M1 and the slave transistor M2, as well as non-ideal factors such as the inductor DCR, when the buck converter is operating in steady state, according to the ampere-second balance, we can obtain:

[0135]

[0136] We can obtain:

[0137]

[0138] like Figure 7 As shown, the on-time generation circuit applied to the buck converter generates the charging current. Reference voltage On-time t on for:

[0139]

[0140] In circuit design, selecting appropriate parameter values ​​makes it possible to This ensures the operating frequency. It is a constant that is independent of the application environment.

[0141] The conduction time generation circuit provided in the above embodiments can not only adaptively adjust the conduction time to keep the converter's operating frequency stable, but also can be flexibly applied to two typical switching power supply conversion circuits: boost converters and buck converters. It has a wide range of applications, low circuit complexity, simple and easy design, and good robustness.

[0142] Based on the conduction time generation circuit provided in the above embodiments, this application also provides a DC-DC converter, which may include: a DC-DC conversion circuit and a conduction time generation circuit of any of the above embodiments, wherein the output terminal of the conduction time generation circuit is used to connect to the control terminal of the main body of the DC-DC converter.

[0143] The DC-DC converter can be either a boost converter or a buck converter. The specific connection between the conduction time generation circuit and the boost converter or buck converter is as described above and will not be repeated here.

[0144] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A conduction time generation circuit, characterized in that, Applied to a DC-DC converter, the on-time generation circuit includes: a voltage detection module, a reference voltage generation module, a comparator, and a latch; The input terminal of the voltage detection module is used to connect to the input or output terminal of the DC-DC converter to generate a detection voltage based on the input or output voltage of the DC-DC converter. The output terminal of the voltage detection module is connected to the positive input terminal of the comparator. The voltage input terminal of the reference voltage generation module is used to obtain multiple voltage values ​​of the DC-DC converter, and the current input terminal of the reference voltage generation module is used to obtain the inductor current of the DC-DC converter, so as to generate a reference voltage based on the multiple voltage values ​​and inductor current of the DC-DC converter. The output terminal of the reference voltage generation module is connected to the negative input terminal of the comparator. The output of the comparator is connected to the reset terminal of the latch to provide an on-time signal to the latch based on the comparison result of the detected voltage and the reference voltage. The set terminal of the latch is used to receive a pulse control signal, and the output terminal of the latch is used to connect to the control terminal of the main body of the DC-DC converter, so as to control the main body of the DC-DC converter during the conduction time according to the conduction time signal. The reference voltage generation module includes: a second voltage-to-current conversion module, a resistance module, a current sensing module, and an impedance detection module; The input terminal of the second voltage-to-current conversion module and the voltage input terminal of the impedance detection module serve as the voltage input terminal of the reference voltage generation module. The output terminal of the second voltage-to-current conversion module is connected to the first terminal of the resistor module and serves as the output terminal of the reference voltage generation module. The input terminal of the current sensing module serves as the current input terminal of the reference voltage generation module, and the output terminal of the current sensing module is connected to the second terminal of the resistor module and the current input terminal of the impedance detection module. The impedance detection module is also used to acquire the control signal of the slave transistor of the DC-DC converter and the equivalent resistance value of the inductor of the DC-DC converter. The output terminal of the impedance detection module is connected to the control terminal of the resistor module to adjust the voltage division ratio of the resistor module.

2. The conduction time generation circuit as described in claim 1, characterized in that, The voltage detection module includes: a first voltage-to-current conversion module and a charging capacitor; The input terminal of the first voltage-to-current conversion module serves as the input terminal of the voltage detection module, and the output terminal of the first voltage-to-current conversion module is connected to one end of the charging capacitor as the output terminal of the voltage detection module, while the other end of the charging capacitor is grounded.

3. The conduction time generation circuit as described in claim 2, characterized in that, The voltage detection module further includes: an inverter and a first power transistor; The input terminal of the inverter is connected to the output terminal of the latch, the output terminal of the inverter is connected to the gate of the first power transistor, the drain of the first power transistor is connected to one end of the charging capacitor, and the source of the first power transistor is connected to the other end of the charging capacitor.

4. The conduction time generation circuit as described in claim 1, characterized in that, The resistor module includes: a fixed resistor unit and an adjustable resistor unit; One end of the fixed resistor unit serves as the first end of the resistor module, the other end of the fixed resistor unit is connected to one end of the adjustable resistor unit as the second end of the resistor module, the other end of the adjustable resistor unit is grounded, and the control end of the adjustable resistor unit serves as the control end of the resistor module.

5. The conduction time generation circuit as described in claim 1, characterized in that, The current sensing module includes: a second power transistor, a third power transistor, and a current operational amplifier; The gates of the second power transistor and the third power transistor are connected to the gate of the main power transistor of the DC-DC converter. One of the drain and source terminals of the second power transistor is connected to one of the drain and source terminals of the slave transistor of the DC-DC converter, and the other of the drain and source terminals of the second power transistor is connected to the first input terminal of the current operational amplifier. One of the drain and source terminals of the third power transistor is connected to the other of the drain and source terminals of the slave transistor of the DC-DC converter, and the other of the drain and source terminals of the third power transistor is connected to the first input terminal of the current operational amplifier. The output terminal of the current operational amplifier serves as the output terminal of the current sensing module.

6. The conduction time generation circuit as described in claim 1, characterized in that, The impedance detection module includes: an impedance calculation unit and an adder; The voltage input terminal of the impedance calculation unit serves as the voltage input terminal of the impedance detection module, and the current input terminal of the impedance calculation unit serves as the current input terminal of the impedance detection module. The control terminal of the impedance calculation unit receives the control signal from the slave transistor of the DC-DC converter. The output terminal of the impedance calculation unit is connected to one input terminal of the adder, and the other input terminal of the adder obtains the inductance equivalent resistance value of the DC-DC converter. The output terminal of the adder serves as the output terminal of the impedance detection module.

7. The conduction time generation circuit as described in claim 1, characterized in that, If the DC-DC converter is a boost converter, the input terminal of the voltage detection module is connected to the output terminal of the DC-DC converter, the input terminal of the second voltage-to-current conversion module is connected to the input and output terminals of the boost converter to obtain the input voltage and output voltage of the boost converter, and the voltage input terminal of the impedance detection module is connected to the output terminal of the boost converter and the connection point of the main and slave tubes of the boost converter to obtain the output voltage and switching voltage of the boost converter.

8. The conduction time generation circuit as described in claim 1, characterized in that, If the DC-DC converter is a buck converter, the input terminal of the voltage detection module is connected to the input terminal of the DC-DC converter, the input terminal of the second voltage-to-current conversion module is connected to the output terminal of the buck converter to obtain the output voltage of the buck converter, and the voltage input terminal of the impedance detection module is connected to the connection point of the main and slave tubes of the buck converter and ground to obtain the switching voltage and ground voltage of the buck converter.

9. A DC-DC converter, characterized in that, The DC-DC converter includes a DC-DC conversion circuit and an on-time generation circuit. The output terminal of the on-time generation circuit is used to connect to the control terminal of the main body of the DC-DC converter. The on-time generation circuit is the circuit described in any one of claims 1-8.

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