阅读说明：本技术 一种波峰检测电路及其应用 (Wave crest detection circuit and application thereof ) 是由 不公告发明人 于 2021-06-26 设计创作，主要内容包括：本发明公开一种波峰检测电路及其应用,所述的波峰检测电路包括RC微分电路、基准电路、箝位电路和比较器,比较器根据RC微分电路和箝位电路检测半桥变换器上管与下管连接处SW电压斜率变化情况与基准电路产生的基准电压进行比较,从而定位SW处电压谐振到达波峰时刻,再经过逻辑控制器和已处于等待状态的上管开通控制信号进行逻辑处理,最终实现半桥类拓扑上管开通前死区时间的自适应调节和波峰导通控制,应用本发明的基于半桥变换器的开关电源装置具有开关损耗低及EMI噪声低等优势。(The invention discloses a wave crest detection circuit and application thereof, wherein the wave crest detection circuit comprises an RC differential circuit, a reference circuit, a clamping circuit and a comparator, the comparator compares the change condition of SW voltage slope at the connection part of an upper pipe and a lower pipe of a half-bridge converter detected by the RC differential circuit and the clamping circuit with the reference voltage generated by the reference circuit so as to position the moment when the voltage resonance at the SW reaches the wave crest, and the self-adaptive adjustment and wave crest conduction control of dead time before the opening of the upper pipe in half-bridge topology is finally realized by carrying out logic processing on an upper pipe opening control signal in a waiting state through a logic controller.)

1. A peak detection circuit, which applies a switching power supply device, wherein the main power topology of the switching power supply device is a half-bridge converter, the peak detection circuit comprises: the RC differential circuit, the reference circuit, the clamping circuit and the comparator;

the RC differential circuit is used for converting the voltage change slope of the connection part of the upper tube and the lower tube of the half-bridge converter into a detection voltage V according to a direct proportion relation_RCAnd outputs to the first input end of the comparator;

the reference circuit is used for generating a reference voltage V_REFAnd output to the second input end of the comparator;

the clamping circuit is used for inputting the detection voltage V of the first input end of the comparator_RCMaximum voltage limit ofAt a clamping voltage Vc, and the clamping voltage Vc>The reference voltage V_REF；

The comparator is used for comparing voltage values of the first input end and the second input end of the bridge converter and outputting a voltage signal Vp, and the voltage signal Vp is used for judging whether the voltage at the connection position of the upper tube and the lower tube of the bridge converter reaches the peak moment.

2. The peak detection circuit of claim 1, wherein: the initial level states of the first input terminal, the second input terminal and the voltage signal Vp of the comparator are one of the following four configuration modes:

3. the peak detection circuit of claim 1, wherein: the RC differential circuit comprises a capacitor C1 and a resistor R1, one end of a capacitor C1 is used for being connected to the midpoint of an upper tube and a lower tube of the half-bridge converter or a bootstrap voltage, the other end of the capacitor C1 is simultaneously connected to a first input end of a comparator and one end of a resistor R1, and the other end of the resistor R1 is used for being connected to a power supply common ground GND.

4. The peak detection circuit of claim 1, wherein: the reference circuit comprises a resistor R2 and a MOS transistor Q4, one end of the resistor R2 is used for being connected with a power supply VCC, the other end of the resistor R2 is simultaneously connected with a source electrode of the MOS transistor Q4, a grid electrode of the MOS transistor Q4 and a second input end of the comparator, and a drain electrode of the MOS transistor Q4 is used for being connected to a power supply common ground GND.

5. The peak detection circuit of claim 1, wherein: the clamping circuit comprises a MOS tube Q3, the grid electrode and the drain electrode of the MOS tube Q3 are simultaneously connected with the first input end of the comparator, and the source electrode of the MOS tube Q3 is used for being connected to the power supply common ground GND.

6. The peak detection circuit of claim 1, wherein:

the RC differential circuit comprises a capacitor C1 and a resistor R1, one end of the capacitor C1 is used for being connected to the midpoint of an upper tube and a lower tube of the half-bridge converter or a bootstrap voltage, the other end of the capacitor C1 is simultaneously connected to a first input end of the comparator and one end of the resistor R1, and the other end of the resistor R1 is used for being connected to a power supply common ground GND;

the reference circuit comprises a resistor R2 and a MOS transistor Q4, one end of the resistor R2 is used for being connected with a power supply VCC, the other end of the resistor R2 is simultaneously connected with a source electrode of the MOS transistor Q4, a grid electrode of the MOS transistor Q4 and a second input end of the comparator, and a drain electrode of the MOS transistor Q4 is used for being connected to a power supply common ground GND;

the clamping circuit comprises a MOS tube Q3, the grid electrode and the drain electrode of the MOS tube Q3 are simultaneously connected with the first input end of the comparator, and the source electrode of the MOS tube Q3 is used for being connected to the power supply common ground GND.

7. A switching power supply device comprises a half-bridge converter, a master control IC and a drive IC, wherein the master control IC sends an upper tube control signal HI and a lower tube control signal LI, and generates a drive signal HO and a drive signal LO with certain driving capability after amplification processing of the drive IC, the drive signal HO is used for controlling the on-off of an upper tube, and the drive signal LO is used for controlling the on-off of a lower tube;

the method is characterized in that: further comprising the peak detection circuit of any of claims 1 to 6, and a logic controller; and the logic controller is used for obtaining the second inversion moment of the voltage signal Vp in a working cycle and carrying out logic processing on the second inversion moment and the upper tube control signal HI so that the upper tube of the half-bridge converter is switched on by the driving signal HO at the moment that the voltage signal Vp is inverted from a low level to a high level.

8. The switching power supply device according to claim 7, wherein: the working time sequence of the upper pipe is as follows:

stage t 0-t 1: the voltage at the joint of the upper pipe and the lower pipe is zero, and the voltage V is detected_RCZero, comparator ofOne input end voltage following detection voltage V_RCIs less than the reference voltage V of the second input terminal_REFThe voltage signal Vp is in an initial level state, the control signal HI is in a low level, the control signal HO is in a low level, and the upper tube is kept to be turned off;

stage t 1-t 2: the voltage at the joint of the upper pipe and the lower pipe begins to rise in a resonant mode, the rising slope is large, and the voltage V is detected_RCGradually increased, the voltage at the first input end of the comparator follows the detection voltage V_RCVaries and is still less than the reference voltage V of the second input terminal_REFThe level state of the voltage signal Vp is kept unchanged, the control signal HI is high level, the control signal HO is low level, and the upper tube is still turned off;

stage t 2-t 3: the voltage at the joint of the upper pipe and the lower pipe continues rising, the peak position is not reached at the stage, and the voltage V is detected_RCGradually increasing until clamped at the clamping voltage Vc, wherein the voltage of the first input end of the comparator is the clamping voltage Vc and is greater than the reference voltage V of the second input end thereof_REFWhen the voltage signal Vp is turned over for the first time, the control signal HI is at a high level, the control signal HO is at a low level, and the upper tube is still turned off;

stage t 3-t 4: the voltage resonance at the joint of the upper pipe and the lower pipe rises and approaches the peak position, the voltage slope at the joint of the upper pipe and the lower pipe is relieved, and the voltage V is detected_RCGradually decreases, but the voltage of the first input end of the comparator is still clamped at the clamping voltage Vc, and the voltage of the first input end of the comparator is also the clamping voltage Vc and is greater than the reference voltage V of the second input end of the comparator_REFThe level state of the voltage signal Vp is kept unchanged, the control signal HI is high level, the control signal HO is low level, and the upper tube is still turned off;

stage t 4-t 5: the voltage at the joint of the upper tube and the lower tube reaches the peak position at the time t4, and the voltage of the first input end of the comparator follows the detection voltage V_RCHas been reduced to be less than the reference voltage V of the second input terminal_REFWhen the voltage signal Vp is turned over for the second time, the control signal HI is at a high level, the control signal HO is at a high level, and the upper tube is turned on at the moment and continues to the moment t 5;

by this point the cycle is finished and the next cycle begins and the above stages are repeated.

9. The switching power supply device according to claim 7, wherein: the peak detection circuit and/or the logic controller are integrated into the master control IC or the drive IC, or are integrated into a single IC together with the master control IC and the drive IC.

Technical Field

The present invention relates to switching power supplies, and more particularly to peak detection and control for half-bridge converters.

Background

Fig. 1 shows a schematic diagram of a switching power supply apparatus based on a half-bridge converter, which includes a main control IC, a driver IC and a half-bridge converter, wherein the main control IC is a PWM controller, the driver IC is a conventional half-bridge type driver IC, and includes a high-side input signal pin HI, a low-side input signal pin LI, a power supply pin VDD, a low-side reference ground pin VSS, a high-side bootstrap voltage pin HB, a high-side reference ground pin HS, a high-side drive signal output pin HO and a low-side drive signal output pin LO, and the half-bridge type converter generally includes an input power Vin, a power common ground GND, a switching transistor Q1, a synchronous switching transistor Q2 and an energy storage element T.

In the circuit, the switching tube Q1 is also referred to as an upper tube, the synchronous switching tube Q2 is also referred to as a lower tube, and a connection point between the source of the switching tube Q1 and the drain of the synchronous switching tube Q2 is also referred to as an upper tube and lower tube connection point SW.

The working principle of the circuit is as follows: the master IC sends out a top tube control signal HI and a bottom tube control signal LI, drive signals HO and LO with certain driving capability are generated after amplification processing of the drive IC, the HO and the LO are complementary signals, when a top tube Q1 is driven to be turned on by a high side drive signal HO, an input power Vin is excited by a Q1 to generate stable output voltage, and when the top tube Q1 is turned off and a bottom tube Q2 is driven to be turned on by a low side drive signal, Q2 follow current is demagnetized by the energy storage element T to maintain stable output voltage.

In order to prevent the upper and lower tubes from being connected in common, most of master control ICs or drive ICs can reserve certain dead time between control signals or drive signals of the upper and lower tubes during design and development, the dead time between the turn-off of the upper tube and the turn-on of the lower tube can be called as the dead time of the lower tube, the dead time between the turn-off of the lower tube and the turn-on of the upper tube can be called as the dead time of the upper tube, the dead time is mainly set and adjusted by means of external pins of the ICs, the upper and lower tubes are all turned off in the dead time, and the energy storage element resonates with parasitic capacitance of a switching tube.

Fig. 2 is a top tube peak conduction waveform diagram. When the half-bridge topology is operated in a critical mode, when the current I flows through an energy storage element inductor or a transformer_LAfter the voltage drops to zero, the parasitic capacitance of the energy storage element and the switching tube starts to resonate, and when the SW voltage at the junction of the upper tube and the lower tube resonates to the maximum value, the upper tube is conducted, which is generally called as peak conduction, and in this state, the switching loss can be reduced and the EMI of the switching power supply can be improved.

FIG. 3 is a waveform diagram of the conduction when the upper tube dead time is too small, and the upper tube dead time t is also required when the peak conduction can reduce the switching loss_deadWhen the dead time of the upper tube is too small, the SW voltage at the joint of the upper tube and the lower tube is conducted in the resonance rising process, and the current I of the energy storage device_LStill negative, the effect of reducing switching losses is limited at this time, and the efficiency of the switching power supply is not necessarily improved.

FIG. 4 shows the upper tube dead zoneWhen the time is too large, the conduction waveform is as the dead time t of the upper tube_deadWhen the voltage is too large, the SW voltage at the joint of the upper tube and the lower tube jumps over the first resonance peak value and reaches the descending section, and then the upper tube is conducted, so that the current I of the energy storage element is increased_LThe conduction loss when the resonance is positive and the upper tube is turned on at the falling edge of the resonance does not effectively reduce the switching loss, and theoretically, the efficiency of the switching power supply can be reduced when the switching power supply is operated in the state.

To sum up, the dead time is set and adjusted mainly by using an external pin of the IC by using a conventional method, and when the dead time can only be set to a fixed value, the dead time cannot be automatically adjusted according to different input/output conditions of the power circuit under the same specification of the switching power supply, which easily causes the dead time to be too small or too large when the input/output conditions are changed, and further cannot ensure that the upper tube is turned on at a wave crest, thereby affecting the efficiency of the switching power supply within the full working condition range.

Disclosure of Invention

In view of the technical defect that the dead time cannot be adaptively adjusted and the automatic peak detection cannot be performed in the conventional switching power supply device based on the half-bridge converter, so that the efficiency is affected, the technical problem to be solved by the invention is to provide a peak detection method and application thereof.

In order to achieve the above object, the peak detection circuit provided by the present invention adopts the following technical scheme:

a peak detection circuit, which applies a switching power supply device, wherein the main power topology of the switching power supply device is a half-bridge converter, the peak detection circuit comprises: the RC differential circuit, the reference circuit, the clamping circuit and the comparator;

the RC differential circuit is used for converting the voltage change slope of the connection part of the upper tube and the lower tube of the half-bridge converter into a detection voltage V according to a direct proportion relation_RCAnd outputs to the first input end of the comparator;

the reference circuit is used for generating a baseQuasi voltage V_REFAnd output to the second input end of the comparator;

the clamping circuit is used for inputting the detection voltage V of the first input end of the comparator_RCIs limited to a clamping voltage Vc, and the clamping voltage Vc>The reference voltage V_REF；

The comparator is used for comparing voltage values of the first input end and the second input end of the bridge converter and outputting a voltage signal Vp, and the voltage signal Vp is used for judging whether the voltage at the connection position of the upper tube and the lower tube of the bridge converter reaches the peak moment.

Further, the initial level states of the first input terminal, the second input terminal, and the voltage signal Vp of the comparator are one of the following four configuration modes:

as a specific embodiment of the RC differentiating circuit, the following features: the half-bridge inverter comprises a capacitor C1 and a resistor R1, wherein one end of the capacitor C1 is used for being connected to the midpoint of an upper tube and a lower tube of a half-bridge inverter or a bootstrap voltage, the other end of the capacitor C1 is simultaneously connected to a first input end of a comparator and one end of a resistor R1, and the other end of the resistor R1 is used for being connected to a power supply common ground GND.

A specific embodiment of the reference circuit is characterized in that: the power supply circuit comprises a resistor R2 and a MOS transistor Q4, wherein one end of the resistor R2 is used for being connected with a power supply VCC, the other end of the resistor R2 is simultaneously connected with a source electrode of the MOS transistor Q4, a grid electrode of the MOS transistor Q4 and a second input end of a comparator, and a drain electrode of the MOS transistor Q4 is used for being connected to a power supply common ground GND.

As a specific embodiment of the clamp circuit, the following features: the MOS tube Q3 is included, the grid and the drain of the MOS tube Q3 are simultaneously connected with the first input end of the comparator, and the source of the MOS tube Q3 is used for being connected to the power supply common ground GND.

As a specific embodiment of the peak detection circuit, the peak detection circuit is characterized in that:

the RC differential circuit comprises a capacitor C1 and a resistor R1, one end of the capacitor C1 is used for being connected to the midpoint of an upper tube and a lower tube of the half-bridge converter or a bootstrap voltage, the other end of the capacitor C1 is simultaneously connected to a first input end of the comparator and one end of the resistor R1, and the other end of the resistor R1 is used for being connected to a power supply common ground GND;

the reference circuit comprises a resistor R2 and a MOS transistor Q4, one end of the resistor R2 is used for being connected with a power supply VCC, the other end of the resistor R2 is simultaneously connected with a source electrode of the MOS transistor Q4, a grid electrode of the MOS transistor Q4 and a second input end of the comparator, and a drain electrode of the MOS transistor Q4 is used for being connected to a power supply common ground GND;

the clamping circuit comprises a MOS tube Q3, the grid electrode and the drain electrode of the MOS tube Q3 are simultaneously connected with the first input end of the comparator, and the source electrode of the MOS tube Q3 is used for being connected to the power supply common ground GND.

The technical scheme of the application of the wave crest detection circuit provided by the invention is as follows:

a switching power supply device comprises a half-bridge converter, a master control IC and a drive IC, wherein the master control IC sends an upper tube control signal HI and a lower tube control signal LI, and generates a drive signal HO and a drive signal LO with certain driving capability after amplification processing of the drive IC, the drive signal HO is used for controlling the on-off of an upper tube, and the drive signal LO is used for controlling the on-off of a lower tube;

the method is characterized in that: further comprising the peak detection circuit of any of claims 1 to 6, and a logic controller; and the logic controller is used for obtaining the second inversion moment of the voltage signal Vp in a working cycle and carrying out logic processing on the second inversion moment and the upper tube control signal HI so that the upper tube of the half-bridge converter is switched on by the driving signal HO at the moment that the voltage signal Vp is inverted from a low level to a high level.

Further, the working sequence of the upper tube is as follows:

stage t 0-t 1: the voltage at the joint of the upper pipe and the lower pipe is zero, and the voltage V is detected_RCZero, first input of comparatorInput end voltage following detection voltage V_RCIs less than the reference voltage V of the second input terminal_REFThe voltage signal Vp is in an initial level state, the control signal HI is in a low level, the control signal HO is in a low level, and the upper tube is kept to be turned off;

stage t 1-t 2: the voltage at the joint of the upper pipe and the lower pipe begins to rise in a resonant mode, the rising slope is large, and the voltage V is detected_RCGradually increased, the voltage at the first input end of the comparator follows the detection voltage V_RCVaries and is still less than the reference voltage V of the second input terminal_REFThe level state of the voltage signal Vp is kept unchanged, the control signal HI is high level, the control signal HO is low level, and the upper tube is still turned off;

stage t 2-t 3: the voltage at the joint of the upper pipe and the lower pipe continues rising, the peak position is not reached at the stage, and the voltage V is detected_RCGradually increasing until clamped at the clamping voltage Vc, wherein the voltage of the first input end of the comparator is the clamping voltage Vc and is greater than the reference voltage V of the second input end thereof_REFWhen the voltage signal Vp is turned over for the first time, the control signal HI is at a high level, the control signal HO is at a low level, and the upper tube is still turned off;

stage t 3-t 4: the voltage resonance at the joint of the upper pipe and the lower pipe rises and approaches the peak position, the voltage slope at the joint of the upper pipe and the lower pipe is relieved, and the voltage V is detected_RCGradually decreases, but the voltage of the first input end of the comparator is still clamped at the clamping voltage Vc, and the voltage of the first input end of the comparator is also the clamping voltage Vc and is greater than the reference voltage V of the second input end of the comparator_REFThe level state of the voltage signal Vp is kept unchanged, the control signal HI is high level, the control signal HO is low level, and the upper tube is still turned off;

stage t 4-t 5: the voltage at the joint of the upper tube and the lower tube reaches the peak position at the time t4, and the voltage of the first input end of the comparator follows the detection voltage V_RCHas been reduced to be less than the reference voltage V of the second input terminal_REFWhen the voltage signal Vp is turned over for the second time, the control signal HI is at a high level, the control signal HO is at a high level, and the upper tube is turned on at the moment and continues to the moment t 5;

by this point the cycle is finished and the next cycle begins and the above stages are repeated.

Preferably, the peak detection circuit and/or the logic controller are integrated into the main control IC or the driver IC, or are integrated into a single IC together with the main control IC and the driver IC.

The working principle of the invention is as follows: the main control IC is used for sending an upper tube control signal HI and a lower tube control signal LI, when the falling edge of the lower tube control signal LI arrives and is turned from high level to low level, the main control IC immediately outputs the rising edge of the upper tube control signal HI which is turned from low level to high level and is in a waiting state in advance, at the moment, the upper tube and the lower tube are all turned off, the energy storage element T resonates with parasitic capacitors of the upper tube and the lower tube in the half-bridge converter, an RC differential circuit in a wave crest detection circuit detects the change condition of the SW voltage slope at the connection part of the upper tube and the lower tube in a direct or indirect mode, the SW resonant voltage rising slope at the connection part of the upper tube and the lower tube is larger at first time, the current flowing through the RC differential circuit is larger at the moment, and the first input end voltage of the comparator follows the detection voltage V_RCGradually increases until the voltage is clamped at the voltage Vc, because the clamping voltage Vc is greater than the reference voltage V of the second input end of the comparator_REFThe output level of the comparator is turned over for the first time; when the voltage resonance at the connection part of the upper tube and the lower tube rises quickly and the slope change is slow near the peak position, the current flowing through the RC differential circuit is gradually reduced until the clamping action of the clamping circuit is relieved, and the voltage of the first input end of the comparator follows the detection voltage V_RCGradually decreases until the voltage is less than the reference voltage V of the in-phase input end_REFThe comparator outputs level for the second time, the voltage signal Vp output by the comparator corresponds to SW voltage resonance of the junction of the upper tube and the lower tube to the peak position at the moment of the second time, the upper tube control signal HI which is in a waiting state in advance can be switched on at the peak position by amplifying the final output upper tube driving signal HO at the moment, the upper tube is ensured to be switched on at the peak position, and the self-adaptive upper tube dead time setting is realized.

Compared with the prior art, the invention has the following beneficial effects:

1) other wave crest detection circuits are not added to the half-bridge converter topology, automatic wave crest detection and self-adaptive dead time adjustment can be realized by integrating the wave crest detection circuit in the drive IC, the switching loss can be reduced, the EMI noise can be improved, and the efficiency of the switching power supply can be improved;

2) the wave crest detection circuit of the invention is integrated in the drive IC, so that the structure of the switch power supply circuit can be simplified, the number of pins of the IC can be combined, and the expansion of the application flexibility is facilitated;

3) the reduction of the switching loss is beneficial to the high frequency of a switching power supply product, the high frequency reduces the inductance value and the capacitance value of an input/output filter capacitor, the size of the switching power supply can be reduced, the power density is improved, and meanwhile, the cost is reduced.

Drawings

Fig. 1 is a schematic diagram of a switching power supply apparatus based on a half-bridge converter;

FIG. 2 is a diagram of a tube peak conduction waveform on a half-bridge converter;

FIG. 3 is a conducting waveform diagram when dead time of a tube on a half-bridge converter is too small;

FIG. 4 is a conduction waveform diagram of a half-bridge converter with excessive tube dead time;

FIG. 5 is a schematic block diagram of a peak detection circuit of the present invention;

FIG. 6 is a schematic block diagram of a peak detection circuit according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a peak detection circuit applied to a half-bridge converter switching power supply apparatus according to an embodiment of the present invention;

FIG. 8 is a timing diagram illustrating the operation of detecting the conduction of the upper transistor under the control of the peak according to the embodiment of the present invention.

The drawings described above do not limit the scope of the inventive concept but illustrate it to those skilled in the art by reference to specific embodiments.

Detailed Description

Fig. 5 is a schematic block diagram of the peak detection circuit of the present invention, which includes an RC differentiating circuit, a reference circuit, a clamping circuit and a comparator U3, the inventive concept of the present application is that the comparator compares the change of the voltage slope at the SW of the upper tube and the lower tube junction with the reference voltage generated by the reference circuit according to the detection of the RC differentiating circuit and the clamping circuit, so as to locate the time when the SW voltage at the upper tube and the lower tube junction reaches the peak, and then performs logic processing with an upper tube turn-on control signal sent by the main control IC and in a waiting state in advance, so as to finally drive the upper tube to turn on at the peak, and realize the adaptive adjustment of the dead time before turning on the tube in the half-bridge topology.

The initial level states of the first input end, the second input end and the voltage signal Vp of the comparator are one of the following four configuration modes:

in order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail in the first configuration described above with reference to the accompanying drawings.

FIG. 6 is a diagram of a peak detection circuit according to an embodiment of the present invention, including an RC differential circuit, a reference circuit, a clamp circuit, and a comparator U3; fig. 7 is a schematic diagram of an application of a peak detection circuit in a half-bridge converter switching power supply apparatus according to an embodiment of the present invention, including a main control IC, a driver IC, the peak detection circuit shown in fig. 6, and a logic controller.

Wherein the RC differential circuit comprises a capacitor C1 and a resistor R1, and one end V of the capacitor C1_SWThe capacitor C1 is connected to the inverting input terminal of the comparator and one end of the resistor R1, and the other end of the resistor R1 is used for connecting to the power supply common ground GND.

The reference circuit comprises a resistor R2 and a MOS transistor Q4, one end of the resistor R2 is used for being connected with a power supply VCC, the other end of the resistor R2 is simultaneously connected with a source electrode of the MOS transistor Q4, a grid electrode of the MOS transistor Q4 and a non-inverting input end of a comparator, and a drain electrode of the MOS transistor Q4 is used for being connected to a power supply common ground GND.

The clamping circuit comprises a MOS tube Q3, the grid and the drain of the MOS tube Q3 are simultaneously connected with the inverting input end of the comparator, and the source of the MOS tube Q3 is used for being connected to the power supply common ground GND.

The output of the comparator U3 is connected to one input of the logic controller.

The logic processor is used for obtaining the moment when the voltage signal Vp is inverted from low level to high level, and performing logic processing with the upper tube control signal HI, so that the drive signal HO switches on the upper tube of the half-bridge converter at the moment when the voltage signal Vp is inverted from low level to high level.

For a half-bridge topology Buck converter with Vin voltage of 48V, Vo voltage of 24V, energy storage element T having inductance of 1.5uH, driving IC power supply VDD of 12V, output current of 4A, and switching frequency of 1MHz, in combination with the operation timing of detecting the conduction of the peak-controlled upper tube shown in fig. 8, a specific operation process is analyzed as follows, it should be noted that there is a delay from when the driving IC sends an upper tube control signal HO to when the upper tube receives the control signal HO, and when "Q1 driving signal HO" in fig. 8 and "driving signal HO" described in other contents in this document are not specifically described, it indicates the time when the upper tube Q1 receives the control signal HO:

stage t 0-t 1: the voltage at the joint of the upper pipe and the lower pipe is zero, and the detected voltage change slope at the joint of the upper pipe and the lower pipe is converted into a voltage value V after the voltage is converted into_RCZero, the voltage at the inverting input of comparator U3 follows voltage V_RCIs less than the reference voltage V of the non-inverting input end thereof_REFThe comparator U3 outputs a high level signal, the control signal HI is low level, the control signal HO is low level, and the upper tube is kept off;

stage t 1-t 2: the voltage at the joint of the upper tube and the lower tube starts to rise in resonance, the rising slope is large, and the voltage V is_RCAnd also gradually increases, the voltage at the inverting input of the comparator U3 follows the voltage V_RCVaried and still smaller than the reference voltage V of the non-inverting input terminal_REFIt should be noted that, in order to ensure that the time when the up-tube control signal HI changes to the high level is earlier than the time when the comparison result signal output by the comparator U3 inverts to the low level, the time when the up-tube control signal HI changes to the high level should be at the inverse of the comparatorDetection voltage V input by phase input end_RCWhen the voltage is increased to the clamp voltage Vc, namely the control signal HI at the stage needs to be changed into high level and is in a state of advanced waiting;

stage t 2-t 3: the voltage at the joint of the upper pipe and the lower pipe continues to rise, the peak position is not reached yet at this stage, and the voltage V_RCGradually increase until being clamped at V_RCThe highest voltage amplitude of the comparator U3 is the clamping voltage Vc, and the voltage at the inverting input end of the comparator U3 is the clamping voltage Vc and is greater than the reference voltage V at the non-inverting input end of the comparator_REFThe output signal of the comparator U3 is inverted from high level to low level, the control signal HI is high level, the control signal HO is low level, and the upper tube is still turned off;

stage t 3-t 4: the voltage resonance at the joint of the upper pipe and the lower pipe rises and approaches the peak position, the voltage slope at the joint of the upper pipe and the lower pipe is reduced, and the voltage V is_RCThe voltage at the inverting input terminal of the comparator U3 is still clamped at the clamping voltage Vc, and the voltage at the inverting input terminal of the comparator U3 is still the clamping voltage Vc at the moment and is still larger than the reference voltage V at the non-inverting input terminal of the comparator_REFThe output signal of the comparator U3 still keeps low level, the control signal HI is high level, the control signal HO is low level, and the upper tube still keeps off;

stage t 4-t 5: the voltage at the joint of the upper tube and the lower tube reaches the peak position at the time of t4, and the voltage of the inverting input end of the comparator U3 follows the voltage V_RCHas been reduced to be less than the reference voltage V of the non-inverting input terminal thereof_REFThe output signal of the comparator U3 is inverted from low level to high level, the control signal HI is high level, the control signal HO is high level, at this time, the upper tube is turned on at the peak and continues to the time t5, it should be noted that the inherent delay effect of the IC internal integrated device is considered, specifically, the reference circuit generates the reference voltage V_REFWhen the output voltage of the clamp circuit reaches the clamp voltage Vc, the voltage of the inverting input terminal of the comparator is gradually reduced from the clamp voltage Vc due to the gradual reduction of the current flowing through the RC differential circuit, and the clamp voltage Vc is reduced to the reference voltage V_REFTime deviation exists, in order to ensure that the upper tube is accurate at the position of the resonance peakQuasi-turn-on, which is to ensure that the time deviation of the clamp voltage Vc generated by the clamp circuit reduced to the reference voltage Vref generated by the reference circuit is matched with the time delay from the output of the comparison result signal of the comparator U3 to the conversion from the high level to the conversion from the upper tube driving signal HO to the high level, namely, in the actual circuit design, the driving IC should send out the high level HO signal in advance to ensure that the upper tube just receives the high level HO signal at the moment of t 4;

by this point the cycle is finished and the next cycle begins and the above stages are repeated.

It should be noted that, in order to improve the integration level of the product, the peak detection circuit and/or the logic controller of the present invention are integrated into the main control IC or the driver IC, or are integrated into a single IC together with the main control IC and the driver IC.

The above embodiments should not be construed as limiting the present invention, and the scope of the present invention should be determined by the scope of the appended claims. It will be apparent to those skilled in the art that many equivalent substitutions, modifications and alterations can be made without departing from the spirit and scope of the invention, such as fine tuning of the circuit by simple series-parallel connection of devices, etc., depending on the application, and such modifications and alterations should also be considered as the scope of the invention.