Semiconductor device, current resonance type power supply and control method thereof

Abstract

The embodiment of the invention provides a semiconductor device, a current resonance type power supply and a control method thereof. The semiconductor device for controlling a current resonance type power supply includes: a load detection circuit for detecting a load state of the current resonance type power supply; a frequency setting signal generation circuit that, when the load state is a light load state, generates a first signal and a second signal on the basis of a feedback signal that changes in opposition to the output signal of the current resonant power supply, and generates a frequency setting signal on the basis of the first signal and the second signal; wherein the first signal is a signal obtained by multiplying a feedback signal by a numerical value N; a burst oscillation circuit that generates a burst oscillation start signal on the basis of the frequency setting signal; and a switching control circuit that generates a signal for alternately turning on / off a first switching element and a second switching element, which are connected in series with the current resonant power supply, on the basis of the frequency setting signal and the burst oscillation activation signal. According to the method and the device, the sudden action can be easily adjusted by adjusting the value of N.

Description

Technical Field

[0001] The embodiments of the present application relate to the semiconductor field, and in particular to a semiconductor device, a current resonance power supply and a control method thereof. Background Art

[0002] In order to maintain the efficiency of the current resonance type power supply device at a light load, the current resonance type power supply device can be controlled to operate in a burst oscillation mode when the load state is light load to reduce the loss in the circuit. At this time, in order to suppress the rapid change of the drain current of the switching element in the current resonance type power supply device, it is necessary to control the burst oscillation operation and the period of the burst oscillation at an appropriate frequency.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology part of the present application. Summary of the invention

[0004] The inventors have found that the frequency of the burst oscillation mode can be set according to the voltage of a specific terminal. For example, in the patent document with publication number JP2016052161A, according to the voltage V SB Set the frequency of the burst oscillation mode. However, in this mode, the switching times of the switching element of the current resonance type power supply device are large, and there is reactive power on the primary side of the current resonance type power supply device that is not sent to the secondary side, so the loss is large; at the same time, the output overshoot (ripple) of the current resonance type power supply device is also large.

[0005] In the patent document with publication number JP2016111758A, according to the voltage V of the CS terminal of the control IC CS and the FB terminal voltage V FB However, in this method, since the signal at the FB terminal is set to an external phase compensation constant in a manner that optimizes the operation during stable operation, it is difficult to adjust the burst operation in a manner that does not affect the operation during stable operation (for example, the number of switching times, burst cycle, noise, etc.).

[0006] In view of at least one of the above problems, embodiments of the present application provide a semiconductor device, a current resonance power supply and a control method thereof to reduce power consumption in a light load state.

[0007] According to a first aspect of an embodiment of the present application, a semiconductor device is provided, the semiconductor device being used to control a current resonance type power supply, the current resonance type power supply comprising a first switch element and a second switch element connected in series between an output terminal of an AC power supply and a ground terminal, the semiconductor device comprising:

[0008] A load detection circuit, which is used to detect the load state of the current resonance type power supply;

[0009] a frequency setting signal generating circuit, which generates a first signal and a second signal according to a feedback signal having a change opposite to that of an output signal of the current resonance type power supply when the load detection circuit detects that the load state is a light load state, and generates a frequency setting signal according to the first signal and the second signal; wherein the first signal is a signal obtained by multiplying the feedback signal by a value N, the second signal is a signal that increases when the feedback signal is greater than a preset first threshold value and decreases when the feedback signal is less than a preset second threshold value, and the frequency setting signal is the smaller signal between the first signal and the second signal;

[0010] a burst oscillation circuit that generates a burst oscillation start signal for causing the first switching element and the second switching element to perform a burst oscillation operation according to the frequency setting signal;

[0011] A switch control circuit generates a drive signal according to the frequency setting signal and the burst oscillation start signal so as to turn on / off the first switch element and the second switch element alternately.

[0012] According to a second aspect of an embodiment of the present application, a control method for a current resonance type power supply is provided, wherein the current resonance type power supply comprises a first switch element and a second switch element connected in series between an output terminal of an AC power supply and a ground terminal, and the method comprises:

[0013] Detecting a load state of the current resonance type power supply;

[0014] When it is detected that the load state is a light load state, a first signal and a second signal are generated according to a feedback signal having an opposite change to the output signal of the current resonance type power supply, and a frequency setting signal is generated according to the first signal and the second signal; wherein the first signal is a signal obtained by multiplying the feedback signal by N times, the second signal is a signal that increases when the feedback signal is greater than a preset first threshold value and decreases when the feedback signal is less than a preset second threshold value, and the frequency setting signal is the smaller signal between the first signal and the second signal;

[0015] generating a burst oscillation start signal for causing the first switching element and the second switching element to perform a burst oscillation operation according to the frequency setting signal;

[0016] A drive signal is generated based on the frequency setting signal and the burst oscillation start signal so as to alternately turn on / off the first switching element and the second switching element.

[0017] According to a third aspect of an embodiment of the present application, a current resonance type power supply is provided, the current resonance power supply comprising:

[0018] A first switch element and a second switch element are connected in series between an output terminal of the AC power source and a ground terminal;

[0019] A series circuit, which is arranged between a connection terminal of the first switching element and the second switching element and a ground terminal;

[0020] The semiconductor device according to the first aspect of the present application controls the first switching element and the second switching element.

[0021] One of the beneficial effects of the embodiments of the present application is that the frequency is set by using the smaller signal of the N-multiplied feedback signal and the voltage signal of the internal terminal generated based on the feedback signal, and the value of N can be changed according to the load demand, thereby adjusting the start and stop time of the burst oscillation mode of the current resonant power supply, reducing reactive power and lowering losses.

[0022] With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.

[0023] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0024] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The elements and features described in one figure or one implementation of the present application embodiment may be combined with the elements and features shown in one or more other figures or implementations. In addition, in the accompanying drawings, similar reference numerals represent corresponding parts in several figures and can be used to indicate corresponding parts used in more than one implementation.

[0026] Figure 1A schematic diagram of a semiconductor device according to an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a current resonance power supply according to an embodiment of the present application;

[0028] Figure 3 A schematic diagram of a circuit structure of a semiconductor device according to an embodiment of the present application;

[0029] Figure 4 Another schematic diagram of the circuit structure of the semiconductor device according to an embodiment of the present application;

[0030] Figure 5 A signal timing diagram of an embodiment of the present application;

[0031] Figure 6 Another signal timing diagram of an embodiment of the present application;

[0032] Figure 7 A schematic diagram of a control method of a current resonance power supply according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] With reference to the accompanying drawings, the above and other features of the present application will become apparent through the following description. In the description and the accompanying drawings, specific embodiments of the present application are specifically disclosed, which show some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations and equivalents falling within the scope of the attached claims.

[0034] In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish different elements in terms of title, but do not indicate the spatial arrangement or temporal order of these elements, etc., and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of the stated features, elements, components or components, but do not exclude the presence or addition of one or more other features, elements, components or components.

[0035] In the embodiments of the present application, the singular forms "a", "the", etc. include plural forms and should be broadly understood as "a kind" or "a type" rather than being limited to the meaning of "one"; in addition, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least in part according to...", and the term "based on" should be understood as "at least in part based on...", unless the context clearly indicates otherwise.

[0036] In the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium / component. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] The present application provides a semiconductor device for controlling a current resonance type power supply. The semiconductor device may be a result of all components being integrated on the same semiconductor chip, or a structure in which some components are integrated on the same semiconductor chip and the non-integrated components are connected to the semiconductor chip through specific terminals, and the present application does not limit this. Figure 1 is a schematic diagram of a semiconductor device according to an embodiment of the present application. Figure 1 As shown, the semiconductor device includes a load detection circuit 1 , a frequency setting signal generation circuit 2 , a burst oscillation circuit 3 , and a switch control circuit 4 , wherein the switch control circuit 4 is used to control a current resonance type power supply 5 .

[0038] In order to facilitate the description of the semiconductor device of the present application, a current resonance type power supply is first provided here, see Figure 2 The subsequent embodiments of this application will be based on Figure 2 The control of the current resonance type power supply shown in the figure is used as an example to explain. It should be noted that the semiconductor device of the present application is not limited to controlling Figure 2 The semiconductor device of the present application is also applicable to the control of a current resonance type power supply having a structure of the type shown, which includes more or fewer components.

[0039] Figure 2 FIG. 5 is a schematic diagram of a current resonance type power supply 5 according to an embodiment of the present application. Figure 2 As shown, the current resonance type power supply 5 includes an AC power supply AC, a full-wave rectifier circuit DB, a first switch element Q1, a second switch element Q2, a transformer T, an inductor Lr, capacitors C1-C3, and diodes D1-D2. The full-wave rectifier circuit DB performs full-wave rectification on the AC voltage output by the AC power supply AC, and outputs the full-wave rectified voltage to the first switch element Q1 and the second switch element Q2 connected in series between the output terminal of the AC power supply AC / full-wave rectifier circuit DB and the ground terminal GND via the capacitor C1. The first switch element Q1 and the second switch element Q2 are composed of switch elements such as MOSFET, for example, N-channel MOSFET, P-channel MOSFET, etc., and the conduction conditions of the first switch element Q1 and the second switch element Q2 are the same, for example, both are high-level conduction, or both are low-level conduction. Figure 2The first switch element Q1 and the second switch element Q2 shown are both N-channel MOSFETs that are turned on at a high level, but the present application is not limited thereto.

[0040] Between the connection point of the first switching element Q1 and the second switching element Q2, for example Figure 2 A series circuit including an inductor Lr for current resonance, a primary winding P of a transformer T, and a capacitor C2 for current resonance is connected between the first pole (e.g., source) of the first switching element Q1 and the second pole (e.g., drain) of the second switching element Q2. The transformer T also includes two secondary windings S1 and S2 connected in series, wherein the first end of the secondary winding S1 is connected to the anode of the diode D1, and the second end is connected to the second end of the secondary winding S2 and is also connected to the ground terminal GND; the first end of the secondary winding S2 is connected to the anode of the diode D2. The cathode of the diode D1 and the cathode of the diode D2 are connected to the first end of the capacitor C3 and serve as the output terminal OUT of the current resonance type power supply 5, and the second end of the capacitor C3 is connected to the ground terminal GND.

[0041] The semiconductor device of the present application is used to control the first switching element Q1 and the second switching element Q2 of the current resonance power supply 5 to perform switching action in the burst oscillation mode at a set frequency in a light load state, that is, the "alternating on / off" action in the burst oscillation mode.

[0042] For example, see also Figure 1 and Figure 2 , the input terminal 11 of the load detection circuit 1 is connected to one end of the primary winding P of the transformer T in the current resonance type power supply 5, and its output terminal 12 is connected to the frequency setting signal generating circuit 2. When the current resonance type power supply 5 is working, the current flowing through the primary winding P includes the circulating current (the current not sent to the secondary winding of the transformer T) and the load current (the current proportional to the output current of the output terminal OUT). The load detection circuit 1 extracts the load current from the primary winding P, detects the load state according to the load current, and outputs a signal corresponding to the load state through its output terminal 12. Among them, the load state includes a light load state and a heavy load state. In the subsequent embodiments, this application will explain the control of the semiconductor device on the current resonance type power supply 5 under the light load state. The control under the heavy load state can be implemented with reference to the prior art, and this application will not be described in detail.

[0043] The first input terminal 21 of the frequency setting signal generating circuit 2 is connected to the output terminal 12 of the load detection circuit 1, and receives the signal corresponding to the load state output by the load detection circuit 1; the second input terminal 22 is connected to the output terminal OUT of the current resonance type power supply 5, and receives the output signal of the current resonance type power supply 5. When the load detection circuit 1 detects that the load state is a light load state and outputs a signal corresponding to the light load state to the frequency setting signal, the frequency setting signal generating circuit 2 generates a feedback signal opposite to the output signal according to the output signal of the output terminal OUT of the current resonance type power supply 5, and generates a first signal and a second signal according to the feedback signal, and generates a frequency setting signal under the light load state according to the first signal and the second signal, specifically, the smaller signal of the first signal and the second signal is used as the frequency setting signal under the light load state, and the frequency setting signal is output through its output terminal 23. Among them, the first signal is a signal obtained by multiplying the feedback signal by the value N, and the second signal is a signal that increases when the feedback signal is greater than the preset first threshold value, and decreases when the feedback signal is less than the preset second threshold value.

[0044] When the load detection circuit 1 detects that the load state is a heavy load state and outputs a signal corresponding to the heavy load state to the frequency setting signal, the frequency setting signal generating circuit 2 generates a feedback signal opposite to the change of the output signal according to the output signal of the output terminal OUT of the current resonance type power supply 5, and uses the feedback signal as the frequency setting signal under the heavy load state. The control under the heavy load state is not described in detail in this application.

[0045] The first input terminal 31 of the burst oscillation circuit 3 is connected to the output terminal 12 of the load detection circuit 1, and receives the signal corresponding to the load state output by the load detection circuit 1; the second input terminal 32 is connected to the output terminal 23 of the frequency setting signal generating circuit 2, and receives the frequency setting signal. When the signal corresponding to the load state output by the load detection circuit 1 is a signal corresponding to the light load state, the burst oscillation circuit 3 generates a burst oscillation start signal for causing the first switching element Q1 and the second switching element Q2 of the current resonance type power supply 5 to perform a burst oscillation operation according to the frequency setting signal.

[0046] The first input terminal 41 of the switch control circuit 4 is connected to the output terminal 23 of the frequency setting signal generating circuit 2 and is used to receive the frequency setting signal, the second input terminal 42 is connected to the output terminal 33 of the burst oscillation circuit 3 and is used to receive the burst oscillation start signal under the light load state, the first output terminal 43 is connected to the gate G1 of the first switch element Q1 of the current resonance type power supply 5, and the second output terminal 44 is connected to the gate G2 of the second switch element Q2 of the current resonance type power supply 5. When the load detection circuit 1 detects the light load state, the switch control circuit 4 generates a drive signal according to the frequency setting signal under the light load state output by the frequency setting signal generating circuit 2 and the burst oscillation start signal under the light load state output by the burst oscillation circuit 3, and the drive signal controls the first switch element Q1 and the second switch element Q2 of the current resonance type power supply 5 to be alternately turned on / off according to the set frequency (i.e., the frequency of the frequency setting signal). The drive signal includes a first drive signal and a second drive signal of opposite levels, the first drive signal is used to control the first switch element Q1, and the second drive signal is used to control the second switch element Q2. When the first drive signal controls the first switch element Q1 to turn on, since the turn-on conditions of the first switch element Q1 and the second switch element Q2 are the same and the second drive signal is opposite to the first drive signal in level, the second drive signal controls the second switch element Q2 to turn off. Conversely, when the first drive signal controls the first switch element Q1 to turn off, the second drive signal controls the second switch element Q2 to turn on.

[0047] It is worth noting that the above Figure 1 and Figure 2 The semiconductor device of the embodiment of the present application is only schematically described, but the present application is not limited thereto. For example, the connection relationship between the modules or components can be appropriately adjusted, and other modules or components can be added, or some modules or components can be reduced. Those skilled in the art can make appropriate modifications based on the above content, and are not limited to the above attached. Figure 1 and Figure 2 Records of.

[0048] Each circuit in the semiconductor device will be described in detail below. Figure 3 is a schematic diagram of a circuit structure of a semiconductor device according to an embodiment of the present application, Figure 4 Another schematic diagram of the circuit structure of the semiconductor device according to an embodiment of the present application. Figure 3 and Figure 4 exemplarily show the specific circuit structures of the load detection circuit 1, the frequency setting signal generating circuit 2, the burst oscillation circuit 3, the switch control circuit 4 and the current resonance type power supply 5, and Figure 3 and Figure 4The load detection circuit 1, the burst oscillation circuit 3, the switch control circuit 4 and the current resonance power supply 5 are exactly the same, only the structure of the frequency setting signal generating circuit 2 is different, and the specific differences will be described in the subsequent embodiments. Figure 3 and Figure 4 The current resonance power supply 5 in Figure 2 The structure shown is the same. For related instructions, please refer to the previous text and will not be repeated here.

[0049] like Figure 3 and Figure 4 As shown, the frequency setting signal generating circuit 2 includes a feedback circuit, an N-multiplication circuit, a first comparison circuit, a signal generating circuit and a second comparison circuit.

[0050] The feedback circuit includes a voltage detector 201 and a photocoupler 202. The voltage detector 201 detects the voltage across the capacitor C3 of the current resonance type power supply 5, that is, the output voltage V OUT The detected output voltage is output to the FB terminal of the frequency setting signal generating circuit 2 through the photocoupler 202. The photocoupler 202 is used to generate a feedback signal V opposite to the output signal according to the output signal of the current resonance type power supply 5. FB The opposite change here means, for example, that when the output signal increases, the feedback signal decreases; when the output signal decreases, the feedback signal increases. This will be explained in detail in the subsequent examples.

[0051] The N-fold circuit is used to convert the feedback signal V FB Multiplying by the value N set in the N-multiplication circuit, the first signal V1 is obtained, that is, V1 = V FB *N. Figure 3 and Figure 4 In the embodiment, the N-folding circuit includes an N-folding module 203 connected to the FB terminal. The value N set in the N-folding circuit is a positive number greater than 1. In practical applications, N can be adjusted accordingly within the value range as needed.

[0052] The first comparison circuit is used to compare the feedback signal V FB , the preset first threshold V r1 and the preset second threshold V r2 Generate control signal V C .exist Figure 3 and Figure 4 In the embodiment, the first comparison circuit includes a first comparator 204, which is a non-inverting comparator with a variable threshold. The non-inverting input terminal of the first comparator 204 is connected to the FB terminal, and the inverting input terminal inputs a preset first threshold value V r1 Or the second threshold V r2 .

[0053] The signal generating circuit is used to generate a signal according to the control signal V C A second signal V2 is generated.

[0054] The second comparison circuit is used to compare the magnitudes of the first signal V1 and the second signal V2, and use the smaller signal of the first signal V1 and the second signal V2 as the frequency setting signal V f Output. Figure 3 and Figure 4 In the example, the second comparison circuit is the comparison module 205 .

[0055] Regarding the structure of the signal generation circuit, Figure 3 and Figure 4 For example, in Figure 3 In the embodiment, the signal generating circuit includes a charge and discharge control unit 206 and a first capacitor C SB The input end of the charge and discharge control unit 206 is connected to the output end of the first comparison circuit, that is, the output end of the first comparator 204, and is started or closed according to the control signal Vc; the first capacitor C SB One end of is connected to the output end of the charge and discharge control unit 206 and the second comparison circuit, that is, an input end of the comparison module 205, and the other end is connected to the ground end, and outputs the second signal V2 to the comparison module 205. FB Greater than the first threshold V r1 In the case of SB The second signal V2 increases, and the threshold of the first comparator 204 changes to the second threshold value V r2 ; In the feedback signal V FB Less than the second threshold V r2 In the case of SB The second signal V2 decreases, and the threshold of the first comparator 204 changes to the first threshold value V r1 .

[0056] exist Figure 4 In the embodiment, the signal generating circuit includes a counter 207. The input end of the counter 207 is connected to the output end of the first comparison circuit, that is, the first comparator 204, and the output end of the counter 207 is connected to the second comparison circuit, that is, an input end of the comparison module 205, and outputs the second signal V2 according to the control signal Vc. FB Greater than the first threshold V r1 In the case of , the count of the counter 207 increases, the second signal V2 corresponding to its count value outputted by the counter increases, and the threshold of the first comparator 204 changes to the second threshold value V r2 ; In the feedback signal V FB Less than the second threshold Vr2 In the case of the first threshold value V r1 Greater than the second threshold V r2 .

[0057] The frequency setting signal generating circuit 2 is connected to the switch control circuit 4 through a switch SW2, and the frequency control in the light load state and the frequency control in the heavy load state are realized by switching the channel of the switch SW2. In the heavy load state, SW2 is connected to the FB terminal, and the feedback signal V FB Under light load conditions, SW2 is connected to the output of the frequency setting signal generating circuit 2, and the frequency setting signal V output by the frequency setting signal generating circuit 2 is output. f The switching of the switch SW2 can be realized according to the control of the load detection circuit 1, which will be described in detail in the subsequent embodiments.

[0058] In practical applications, the semiconductor device may integrate all components of the frequency setting signal generating circuit 2 on the same semiconductor chip 100, or the semiconductor device may integrate some components of the frequency setting signal generating circuit 2 on the same semiconductor chip 100, and the non-integrated components are connected to the semiconductor chip through specific terminals. Figure 3 In the embodiment, the feedback circuit is not integrated but connected to the semiconductor chip 100 via the FB terminal; the first capacitor C of the signal generating circuit SB It is not integrated but connected to the semiconductor chip 100 via the SB terminal. Figure 4 In the embodiment, the feedback circuit is not integrated but connected to the semiconductor chip 100 via the FB terminal. Figure 3 , Figure 4 The counter 207 is used instead of the charge and discharge control unit 206 and the first capacitor C SB , the number of components in the circuit and the number of terminals of the semiconductor device can be reduced. This application is not limited to this.

[0059] Please continue to see Figure 3 and Figure 4 The load detection circuit 1 includes a load current integration unit and a third comparator. The load current integration unit is used to integrate the load current flowing through the primary winding P of the transformer T in the current resonance type power supply 5 to obtain a first voltage value V CL .exist Figure 3 and Figure 4 The load current integration unit includes capacitor C4, resistor R1, resistor R2 and capacitor C CL Among them, the capacitor C4 and the resistor R1 are connected in series between one end of the primary winding P and the ground terminal; the capacitor CCL One end of the capacitor is connected in series with the resistor R2 and connected between the capacitor C4 and the resistor R1, and the other end is grounded. CL A switch SW1 can be connected in series between the resistor R2, and when the switch SW1 is closed, the load detection circuit 1 detects the load state. The switch SW1 can be controlled by a signal output from the high-voltage side output terminal of the oscillator 401 mentioned later, for example, when the signal output from the high-voltage side output terminal is at a high level, the switch SW1 is closed.

[0060] exist Figure 3 and Figure 4 In the embodiment, the third comparator 101 is an inverting comparator 101, and its non-inverting input terminal inputs the third threshold value V r3 , the inverting input terminal and capacitor C CL Connect and input the first voltage value V CL The third comparator 101 is used to CL and the preset third threshold V r3 Determine the load state and at the first voltage value V CL Less than the third threshold V r3 , a signal indicating that the load state is a light load state is output.

[0061] When the load demand is small, the output voltage V OUT becomes smaller. At this time, the load current in the primary winding P of the transformer decreases, and the first voltage value V obtained by the load current integration part by integrating the load current CL When the first voltage value V CL Below the third threshold V r3 When the load demand is large, the output voltage V of the current resonance type power supply 5 is greater than 100V. OUT becomes larger. At this time, the load current in the primary winding P of the transformer increases, and the first voltage value V obtained by the load current integration part by integrating the load current CL When the first voltage value V CL Above the third threshold V r3 When a heavy load state is detected, the third comparator 208 outputs a low level corresponding to the heavy load state, and the low level controls the switch SW2 to turn on the FB terminal.

[0062] In practical applications, the semiconductor device may integrate all components of the load detection circuit 1 on the same semiconductor chip 100, or the semiconductor device may integrate some components of the load detection circuit 1 on the same semiconductor chip 100, and the non-integrated components are connected to the semiconductor chip 100 through specific terminals. Figure 3 and Figure 4 In the embodiment, capacitor C4, resistor R1, and capacitor C CL Without integration, the capacitor C4 and the resistor R1 are connected to the semiconductor chip 100 through the PL terminal; the capacitor C CL The CL terminal is used to connect to the semiconductor chip 100. Thus, the number of components integrated in the semiconductor chip can be reduced, and the area of ​​the semiconductor chip can be reduced.

[0063] Please continue to see Figure 3 and Figure 4 The burst oscillation circuit 3 includes a fourth comparator 301, which is a common-phase comparator with a variable threshold. The common-phase input terminal of the fourth comparator 301 is connected to the output terminal of the frequency setting signal generating module 2, and is used to input the frequency setting signal V f The fourth comparator 301 inputs a preset fourth threshold value V r4 or the preset fifth threshold V r5 The burst oscillation circuit 3, namely the fourth comparator 301, converts the frequency setting signal V f and the preset fourth threshold V r4 and the preset fifth threshold V r5 are compared and the frequency setting signal V f Increases to be greater than the fourth threshold V r4 After that, and at the frequency setting signal V f decreases to less than the fifth threshold V r5 Before, a burst oscillation start signal is output. Specifically, when the frequency setting signal V f Greater than the fourth threshold V r4 In the case of , the fourth comparator 301 outputs a high level, that is, outputs a burst oscillation start signal, and the threshold of the fourth comparator 301 changes to the fifth threshold value V r5 ; In the frequency setting signal V f Less than the fifth threshold V r5 In the case of , the fourth comparator 301 outputs a low level, that is, stops outputting the burst oscillation start signal, and the threshold of the fourth comparator 301 changes to the fourth threshold value V r4 In this application, the fourth threshold V r4 Greater than the fifth threshold V r5 .

[0064] In the present application, the burst oscillation circuit 3 is connected to the switch driving circuit through an OR logic gate 302. One input end of the OR logic gate 302 is connected to the output end of the burst oscillation circuit 3, that is, the output end of the fourth comparator 301, and the other input end is connected to the output end of the load detection circuit 1, that is, the output end of the third comparator 101, through a NOT logic gate. When a light load state is detected, the third comparator 101 outputs a high level and inputs a low level to the OR logic gate 302 through the NOT logic gate connected thereto. At this time, the output of the OR logic gate 302 depends on the output of the fourth comparator 301. When the fourth comparator 301 outputs a low level, the OR logic gate 302 also outputs a low level. When the fourth comparator 301 outputs a high level, the OR logic gate 302 also outputs a high level.

[0065] Please continue to see Figure 3 and Figure 4 The switch control circuit 4 includes an oscillator, a first drive circuit and a second drive circuit. The input end of the oscillator 401 is connected to SW2. In the light load state, SW2 turns on the frequency setting signal generating circuit 2 and receives the frequency setting signal V output by the frequency setting signal generating circuit 2. f , to set the signal V according to the frequency f Generate a pulse signal for controlling the first switch element Q1 and the second switch element Q2, and generate a first drive signal and a second drive signal with opposite levels according to the pulse signal. The oscillator 401 includes a high-voltage side output terminal and a low-voltage side output terminal, the high-voltage side output terminal is connected to the first drive circuit and outputs the first drive signal to the first drive circuit; the low-voltage side output terminal is connected to the second drive circuit and outputs the second drive signal to the second drive circuit.

[0066] The first driving circuit includes an AND logic gate 402 and a high-voltage side driver 403. The two input terminals of the AND logic gate 402 are respectively connected to the high-voltage side output terminal of the oscillator 401 and the output terminal of the OR logic gate 302. The output terminal of the AND logic gate 402 is connected to the input terminal of the high-voltage side driver 403. The output terminal of the high-voltage side driver 403 is connected to the gate of the first switching element Q1.

[0067] The second driving circuit includes an AND logic gate 404 and a low-voltage side driver 405. The two input ends of the AND logic gate 404 are respectively connected to the low-voltage side output end of the oscillator 401 and the output end of the OR logic gate 302, the output end of the AND logic gate 404 is connected to the input end of the low-voltage side driver 405, and the output end of the low-voltage side driver 405 is connected to the gate of the second switching element Q2.

[0068] When the OR logic gate 302 outputs a high level and the first drive signal is also a high level, the AND logic gate 402 outputs a high level, and the high-side driver 403 outputs a drive signal to drive the first switch element Q1 to turn on; at the same time, the second drive signal opposite to the first drive signal level is a low level, and the AND logic gate 404 will output a low level, and the low-side driver 405 does not output a drive signal, that is, the second switch element Q2 is turned off. On the contrary, when the OR logic gate 302 outputs a high level and the first drive signal is a low level, the AND logic gate 402 outputs a low level, the high-side driver 403 does not output a drive signal, and the first switch element Q1 is turned off; at the same time, the second drive signal opposite to the first drive signal level is a high level, and the AND logic gate 404 will output a high level, and the low-side driver 405 outputs a drive signal to drive the second switch element Q2 to turn on. Thus, under the drive of the first drive signal and the second drive signal, the first switch element Q1 and the second switch element Q2 perform the "alternately turned on / off" action in the burst oscillation mode.

[0069] Combination of the above Figure 3 and Figure 4 The specific structures and operating principles of each circuit of the semiconductor device of the present application are described respectively, and the complete process of the semiconductor device controlling the current resonance type power supply 5 under light load state will be described through the following examples.

[0070] Figure 5 is a signal timing diagram provided in an embodiment of the present application, including the output voltage V of the current resonance type power supply 5 OUT , the feedback signal V at the FB terminal FB , the first signal V1 after the feedback signal is multiplied by N, the second signal V2, the frequency setting signal V f , the current signal I on the primary winding side P And the current signal I on the secondary winding side S , the vertical dotted lines represent the same moments.

[0071] Please also see Figure 3 and Figure 5 Before time t1, the output voltage V OUT The load current integration unit of the load detection circuit 1 integrates the current flowing through the primary winding P of the transformer T, so the voltage V CL When V CL is lower than the third threshold value V input to the third comparator 101 r3 ( Figure 5(not shown), the current state is determined to be a light load state, and the third comparator 101 outputs a high level corresponding to the light load state. At this time, the switch SW2 is connected to the output end of the frequency setting signal generating module 2; or the input end of the logic gate 302 connected to the third comparator 101 inputs a low level, or the output of the logic gate 302 is completely dependent on the output of the fourth comparator 301.

[0072] At the same time, as the output voltage V of the current resonance power supply 5 OUT The feedback signal output by the optocoupler 202, i.e., the voltage V at the FB terminal, is reduced. FB The N-multiplication circuit 203 outputs a feedback signal V FB The first signal V1 is multiplied by the value N.

[0073] When it reaches time t1, the feedback signal V FB Increases to exceed the first threshold V r1 At this time, the first comparator 204 outputs a high level, driving the charge and discharge control unit 206 to start, and the first capacitor C SB Charging, accordingly, from time t1, the voltage V SB , that is, the second signal V2 mentioned above increases accordingly. The second comparator 205 compares the first signal V1 with the second signal V2, and outputs the smaller signal as the frequency setting signal V f .

[0074] At time t2, the frequency setting signal V f Exceeding the fourth threshold V r4 , the fourth comparator 301 outputs a high level, that is, outputs a burst oscillation start signal, and at this time, the OR logic gate 302 also outputs a high level. Therefore, the input ends of the AND logic gate 402 and the AND logic gate 404 connected to the output end of the OR logic gate 302 are input with a high level signal, and at this time, the outputs of the AND logic gate 402 and the AND logic gate 404 depend on the output of the oscillator 401. The oscillator 401 is set to the frequency setting signal V fUnder the control of , a pulse signal of a set frequency is generated, and a first drive signal outputted through the high-voltage side output terminal and a second drive signal outputted through the low-voltage side output terminal and having a level opposite to the first drive signal are generated according to the pulse signal. When the high-voltage side output terminal of the oscillator 401 outputs a high level, the AND logic gate 402 outputs a high level, and the high-voltage side driver 403 outputs a drive signal to drive the first switch element Q1 to turn on. At the same time, the low-voltage side output terminal of the oscillator 401 outputs a low level, the AND logic gate 404 outputs a low level, the low-voltage side driver 405 does not output a drive signal, and the second switch element Q2 is turned off. On the contrary, when the high-voltage side output terminal of the oscillator 401 outputs a low level, the AND logic gate 402 outputs a low level, the high-voltage side driver 403 does not output a drive signal, and the first switch element Q1 is turned off. At the same time, the low-voltage side output terminal of the oscillator 401 outputs a high level, the AND logic gate 404 outputs a high level, and the low-voltage side driver 405 outputs a drive signal to drive the second switch element Q2 to turn on. At this time, the current resonance type power supply 5 operates in a burst oscillation mode.

[0075] Before time t3, in the burst oscillation mode, the current resonance type power supply 5 maintains a nearly stable output; after time t3, as the burst oscillation time increases, the output voltage V OUT This is because the first switch element Q1 and the second switch element Q2 of the current resonance type power supply 5 are alternately turned on / off. When the first switch element Q1 is turned on, the inductor Lr stores energy; when the second switch element Q2 is turned on, the energy stored in the inductor Lr maintains the light load requirement; as the number of times the first switch element Q1 and the second switch element Q2 are alternately turned on / off increases, the energy stored in the inductor Lr also gradually increases, making the output voltage V OUT Also increases gradually. Correspondingly, the feedback signal V FB Then it gradually decreases. When the feedback signal V FB Reduced to the second threshold V r2 When the time t5 is reached, the first comparator 204 outputs a low level, and the charge and discharge control unit 206 stops charging the capacitor C SB Charging, capacitor C SB Discharging starts, so the voltage of the SB terminal, ie, the second signal V2, gradually decreases.

[0076] At time t5, the frequency setting signal V f Reduced to the fifth threshold V r5 , the fourth comparator 301 outputs a low level, that is, it no longer outputs the burst oscillation start signal. At this time, the OR logic gate 302 also outputs a low level, and the input ends of the AND logic gate 402 and the AND logic gate 404 connected to the output end of the OR logic gate 302 are input with low level signals. Therefore, the current resonance power supply 5 stops operating in the burst oscillation mode.

[0077] Figure 4 The operating principle of the semiconductor device shown is similar to Figure 3 Similar, the only difference is that the first signal V1 is composed of Figure 3 The voltage V at the SB terminal SB becomes the voltage corresponding to the count value output by the counter 207, that is, Figure 5 The waveform of the second signal V2 shown is slightly different, see Figure 6 The second signal V2' shown in FIG. FB Reduced to the second threshold V r2 When the count value of counter 207 is reset, the signal corresponding to the count value output by the counter also decreases instantaneously, and the rest of the signal is the same as Figure 3 The same. Therefore, Figure 4 The operating principle can be found in Figure 3 The operating principle of is not repeated here.

[0078] It can be seen that under light load conditions, the start and stop of the burst oscillation mode of the current resonance power supply 5 is determined by the frequency setting signal V f When the frequency setting signal V f Increases to exceed the fourth threshold V r4 After that, it decreases to the fifth threshold V r5 Before that, the current resonance power supply 5 will operate in the burst oscillation mode. Therefore, as long as the value of N is reasonably selected, the first signal V1 (V1 = V FB *N), thereby changing the magnitude relationship between the first signal V1 and the second signal V2, thereby changing the frequency setting signal to decrease to the fifth threshold value V r5 moment.

[0079] For example, as described above, the second comparator 205 compares the first signal V1 and the second signal V2, and outputs the smaller signal as the frequency setting signal V f .exist Figure 5 and Figure 6 Before time t4, the second signal V2 (or the second signal V2') is smaller than the first signal V1, and the frequency setting signal V f is the second signal V2 (or the second signal V2'); at time t4, the second signal V2 (or the second signal V2') is equal to the second signal V1; after time t4, the second signal V2 (or the second signal V2') is greater than the first signal V1, therefore, the frequency setting signal V f is the first signal V1. When N takes different values, the time t4 when the first signal V1 and the second signal V2 (or the second signal V2') are equal will also change accordingly.

[0080] In practical applications, the smaller N is, the earlier the t4 moment is, and the frequency setting signal V f The moment of starting to decrease is earlier, and the frequency setting signal V f The sooner it can be reduced to the fifth threshold V r5 Next, the current resonance type power supply 5 stops the switching action in the burst oscillation mode, that is, the first switch element Q1 and the second switch element Q2 stop the "alternating on / off" action in the burst oscillation mode. However, when the value of N is too small, the number of switches is too small, and the period of the burst oscillation becomes shorter. At this time, the current resonance type power supply may not operate in the burst oscillation mode, but in the continuous oscillation mode. Therefore, in practical applications, the burst action can be optimized by appropriately adjusting the value of N.

[0081] Therefore, by changing the value of N, the present application can flexibly adjust the burst action according to the load demand on the secondary side of the transformer T. By advancing the stop time of the burst oscillation mode, the number of switches can be reduced, and reactive power that is not sent to the secondary side on the primary side of the transformer T can be avoided as much as possible, thereby reducing reactive power loss.

[0082] In addition, at time t3 before time t4 when the first signal V1 and the second signal V2 (or the second signal V2') are equal, the output voltage V of the output current resonance type power supply 5 is OUT will gradually increase. During the period between t3 and t4, the output voltage V OUT Therefore, if the value of N is changed to make time t4 arrive earlier, V OUT Increase to an excessively large value, thereby reducing the output overshoot (ripple) ΔV.

[0083] The above embodiments are merely exemplary of the embodiments of the present application, but the present application is not limited thereto, and appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0084] It can be seen from the above embodiments that in a semiconductor device, under a light load state, the present application generates a first signal and a second signal according to a feedback signal that is opposite to the output signal change of the current resonance type power supply, and generates a frequency setting signal according to the first signal and the second signal; wherein the first signal is a signal obtained by multiplying the feedback signal by a value N, and the second signal is a signal that increases when the feedback signal is greater than a preset first threshold value and decreases when the feedback signal is less than a preset second threshold value, and the frequency setting signal is the smaller signal of the first signal and the second signal. Therefore, the present application can change the value of N according to the load demand on the secondary side of the transformer T, and flexibly adjust the burst action. By changing the value of N and advancing the stop time of the burst oscillation mode, the number of switches can be reduced, and the reactive power that is not sent to the secondary side on the primary side of the transformer T can be avoided as much as possible, thereby reducing the loss of reactive power, and at the same time reducing the output overshoot (ripple).

[0085] Figure 7 Schematic diagram of a control method of a current resonance type power supply according to an embodiment of the present application, wherein the current resonance type power supply controlled by the control method of the current resonance type power supply comprises a first switch element and a second switch element connected in series between the output terminal of the AC power supply and the ground terminal. Figure 7 As shown, the control method of the current resonance type power supply includes:

[0086] 701, detecting a load state of the current resonance type power supply;

[0087] 702, when it is detected that the load state is a light load state, generating a first signal and a second signal according to a feedback signal having an opposite change to the output signal of the current resonance type power supply, and generating a frequency setting signal according to the first signal and the second signal; wherein the first signal is a signal obtained by multiplying the feedback signal by N times, the second signal is a signal that increases when the feedback signal is greater than a preset first threshold value and decreases when the feedback signal is less than a preset second threshold value, and the frequency setting signal is the smaller signal between the first signal and the second signal;

[0088] 703, generating a burst oscillation start signal for causing the first switch element and the second switch element to perform a burst oscillation action according to the frequency setting signal;

[0089] 704 , generating a driving signal according to the frequency setting signal and the burst oscillation start signal to turn on / off the first switching element and the second switching element alternately.

[0090] The control method of the current resonance type power supply provided in this embodiment can be implemented based on the semiconductor device of the above embodiment of the present application, or can be implemented by other devices, and the present application does not limit this. Since the control method of the current resonance type power supply of this embodiment is similar to the functions of each circuit of the semiconductor device of the above embodiment of the present application, it can be implemented with reference to the above embodiment and will not be repeated here.

[0091] The present application also provides a current resonance type power supply, which can be found in Figure 3 and Figure 4 The overall schematic diagram is shown. The current resonant power supply comprises:

[0092] A first switch element and a second switch element are connected in series between an output terminal of the AC power source and a ground terminal;

[0093] A series circuit, which is arranged between a connection terminal of the first switching element and the second switching element and a ground terminal;

[0094] As described in the above embodiment of the present application, the semiconductor device controls the first switch element and the second switch element. For the semiconductor device, please refer to the description of the above embodiment of the present application, which will not be repeated here.

[0095] The above embodiments are merely exemplary of the embodiments of the present application, but the present application is not limited thereto, and appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0096] The above devices and methods of the embodiments of the present application can be implemented by hardware, or by hardware combined with software. The present application relates to such a computer-readable program, which, when executed by a logic component, enables the logic component to implement the above-mentioned devices or components, or enables the logic component to implement the various methods or steps described above. The present application also relates to a storage medium for storing the above program, such as a hard disk, a disk, an optical disk, a DVD, a flash memory, etc.

[0097] The method / device described in conjunction with the embodiments of the present application may be directly embodied as hardware, a software module executed by a processor, or a combination of the two. For example, one or more of the functional block diagrams shown in the figure and / or one or more combinations of the functional block diagrams may correspond to various software modules of the computer program flow or to various hardware modules. These software modules may correspond to the various steps shown in the figure, respectively. These hardware modules may be implemented by solidifying these software modules, for example, using a field programmable gate array (FPGA).

[0098] The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium may be coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium; or the storage medium may be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The software module may be stored in a memory of a mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if a device (such as a mobile terminal) uses a large-capacity MEGA-SIM card or a large-capacity flash memory device, the software module may be stored in the MEGA-SIM card or the large-capacity flash memory device.

[0099] For one or more of the functional blocks described in the drawings and / or one or more combinations of functional blocks, it can be implemented as a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component or any appropriate combination thereof for performing the functions described in the present application. For one or more of the functional blocks described in the drawings and / or one or more combinations of functional blocks, it can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication with a DSP, or any other such configuration.

[0100] The present application is described above in conjunction with specific implementation methods, but it should be clear to those skilled in the art that these descriptions are exemplary and are not intended to limit the scope of protection of the present application. Those skilled in the art can make various modifications and variations to the present application based on the spirit and principles of the present application, and these modifications and variations are also within the scope of the present application.

Claims

1. A semiconductor device, characterized in that: The semiconductor device is used to control a current resonance type power supply, the current resonance type power supply includes a first switch element and a second switch element connected in series between an output terminal of an AC power supply and a ground terminal, and the semiconductor device includes: A load detection circuit, which is used to detect the load state of the current resonance type power supply; a frequency setting signal generating circuit, which generates a first signal and a second signal according to a feedback signal having a change opposite to that of an output signal of the current resonance type power supply when the load detection circuit detects that the load state is a light load state, and generates a frequency setting signal according to the first signal and the second signal; wherein the first signal is a signal obtained by multiplying the feedback signal by a value N, the second signal is a signal that increases when the feedback signal is greater than a preset first threshold value and decreases when the feedback signal is less than a preset second threshold value, and the frequency setting signal is the smaller signal between the first signal and the second signal; a burst oscillation circuit that generates a burst oscillation start signal for causing the first switching element and the second switching element to perform a burst oscillation operation according to the frequency setting signal; A switch control circuit generates a drive signal according to the frequency setting signal and the burst oscillation start signal so as to turn on / off the first switch element and the second switch element alternately.

2. The semiconductor device according to claim 1, wherein: The frequency setting signal generating circuit comprises: a photocoupler for generating the feedback signal according to the output signal of the current resonance type power supply; An N-multiplication circuit, which multiplies the feedback signal by the value N to obtain the first signal; a first comparison circuit, configured to generate a control signal according to the feedback signal, the first threshold and the second threshold; a signal generating circuit, which generates the second signal according to the control signal; A second comparison circuit compares the first signal and the second signal and outputs a smaller signal between the first signal and the second signal as a frequency setting signal.

3. The semiconductor device according to claim 2, wherein: The signal generating circuit comprises: a charge and discharge control unit, whose input end is connected to the output end of the first comparison circuit and is started or shut down according to the control signal; a first capacitor, one end of which is connected to the output end of the charge and discharge control unit and one input end of the second comparison circuit, the other end of which is connected to the ground end, and outputs the second signal to the second comparison circuit; When the feedback signal is greater than the first threshold, the charge and discharge control unit is started, the first capacitor is charged, and the second signal increases; when the feedback signal is less than the second threshold, the charge and discharge control unit is turned off, the first capacitor is discharged, and the second signal decreases.

4. The semiconductor device according to claim 2, wherein: The signal generating circuit comprises: a counter, whose input terminal is connected to the output terminal of the first comparison circuit, whose output terminal is connected to an input terminal of the second comparison circuit, and which outputs the second signal according to the control signal; When the feedback signal is greater than the first threshold, the count of the counter increases and the second signal increases; when the feedback signal is less than the second threshold, the count of the counter is reset and the second signal decreases.

5. The semiconductor device according to claim 1, wherein: The load detection circuit comprises: a load current integrating unit for integrating the load current flowing through the current resonance type power supply to obtain a first voltage value; The third comparator determines the load state according to the first voltage value and a preset third threshold value, and outputs a signal indicating that the load state is a light load state when the first voltage value is less than the third threshold value.

6. The semiconductor device according to claim 1, wherein: The burst oscillation circuit comprises: a fourth comparator, which compares the frequency setting signal with a preset fourth threshold and a preset fifth threshold respectively, and outputs the burst oscillation start signal after the frequency setting signal increases to be greater than the fourth threshold and before the frequency setting signal decreases to be less than the fifth threshold.

7. The semiconductor device according to claim 1, wherein: The switch control circuit comprises: an oscillator that generates a pulse signal for controlling the first switching element and the second switching element according to the frequency setting signal; a first driving circuit, which generates a first driving signal according to the pulse signal and the burst oscillation start signal, and sends the first driving signal to the first switching element; a second driving circuit, which generates a second driving signal according to the pulse signal and the burst oscillation start signal, and sends the second driving signal to the second switching element; Wherein, under the driving of the first driving signal and the second driving signal, the first switching element and the second switching element are alternately turned on / off.

8. The semiconductor device according to any one of claims 1 to 7, characterized in that The value N is a positive number greater than 1.

9. A control method for a current resonance type power supply, the current resonance type power supply comprising a first switch element and a second switch element connected in series between an output terminal of an AC power supply and a ground terminal, characterized in that: The method comprises: Detecting a load state of the current resonance type power supply; When it is detected that the load state is a light load state, a first signal and a second signal are generated according to a feedback signal having an opposite change to the output signal of the current resonance type power supply, and a frequency setting signal is generated according to the first signal and the second signal; wherein the first signal is a signal obtained by multiplying the feedback signal by N times, the second signal is a signal that increases when the feedback signal is greater than a preset first threshold value and decreases when the feedback signal is less than a preset second threshold value, and the frequency setting signal is the smaller signal between the first signal and the second signal; generating a burst oscillation start signal for causing the first switching element and the second switching element to perform a burst oscillation operation according to the frequency setting signal; A drive signal is generated based on the frequency setting signal and the burst oscillation start signal so as to alternately turn on / off the first switching element and the second switching element.

10. A current resonance power supply, characterized in that: The current resonant power supply comprises: A first switch element and a second switch element are connected in series between an output terminal of the AC power source and a ground terminal; A series circuit, which is arranged between a connection terminal of the first switching element and the second switching element and a ground terminal; The semiconductor device according to any one of claims 1 to 8, wherein the first switching element and the second switching element are controlled.

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