A BOOST circuit, its control circuit and control method

Abstract

This application discloses a BOOST circuit, including: a high-side power transistor and a low-side power transistor, connected in series between the output terminal of the BOOST circuit and a reference ground. The high-side power transistor and the low-side power transistor are jointly coupled to a switching node, and the high-side power transistor provides an output voltage to the output terminal of the BOOST circuit; and a high-side power transistor control circuit, providing a high-side power transistor control signal to control the on / off state of the high-side power transistor. The high-side power transistor control signal has a first level state and a second level state. In buck mode, the voltage difference across the high-side power transistor is adjusted by regulating the value of the first level state of the high-side power transistor control signal. In buck mode, the BOOST circuit provided by this application couples the body terminal of the high-side power transistor to the output voltage and controls the conduction state of the high-side power transistor to reduce the voltage difference across the high-side power transistor, thereby reducing the power consumption of the high-side power transistor and improving circuit efficiency.

Description

Technical Field

[0001] This invention relates to electronic circuits. More specifically, this invention relates to BOOST circuits and their control circuits and methods. Background Technology

[0002] A voltage converter is used to transform an input voltage into an output voltage. Voltage converters include BUCK circuits, BOOST circuits, BUCK-BOOST circuits, and flyback circuits. BOOST circuits are typically used in applications where the output voltage is higher than the input voltage. However, in a BOOST circuit, the input voltage may be higher than the output voltage at certain times, such as during circuit startup when the output voltage has not yet been established, or due to sudden load changes causing a drop in the output voltage. At these times, the input voltage of the BOOST circuit is usually higher than the output voltage. In these situations, the BOOST circuit typically operates in down mode.

[0003] Figure 1 This is a schematic diagram of a typical BOOST circuit 100. The BOOST circuit 100 includes: an input terminal 101, an output terminal 103, a switching node 102, a high-power transistor P11, a low-power transistor P12, and an inductor L1. The input terminal 101 receives the input voltage VIN. The output terminal 103 provides the output voltage VOUT. The high-power transistor P11 is coupled between the switching node 102 and the output terminal 103. The low-power transistor P12 is coupled between the switching node 102 and the reference ground GND. The inductor L1 is coupled between the switching node 102 and the input terminal 101. By switching the high-power transistor P11 and the low-power transistor P12, the input voltage VIN is converted into the output voltage VOUT. In the prior art, the high-power transistor P11 of the BOOST circuit 100 is typically a PMOS transistor, with its drain coupled to the switching node 102 and its source coupled to the output terminal 103. It also has a body diode D11, and the connection method is as follows: Figure 1 As shown. When the BOOST circuit 100 operates in buck mode, the lower power transistor P12 is either turned on or off, while the upper power transistor P11 is turned off. When both lower power transistors P12 and P11 are turned off simultaneously, the switching voltage VSW at switching node 102 rises to a level greater than the input voltage VIN, and therefore also greater than the output voltage VOUT. The body diode D11 of the upper power transistor P11 then conducts forward. However, the high forward voltage drop of the body diode D11 results in significant power dissipation in the upper power transistor P11. Summary of the Invention

[0004] This application provides a BOOST circuit and its control circuit and control method. In buck mode, the BOOST circuit couples the body terminal of the power transistor to the output voltage and controls the conduction state of the power transistor to reduce the voltage difference across the power transistor, reduce the power consumption of the power transistor, and improve circuit efficiency.

[0005] According to an embodiment of the present invention, a BOOST circuit is provided, comprising: a power upper transistor and a power lower transistor, connected in series between the output terminal of the BOOST circuit and a reference ground, wherein the power upper transistor and the power lower transistor are jointly coupled to a switching node, and the power upper transistor provides an output voltage to the output terminal of the BOOST circuit; and a power upper transistor control circuit, providing a power upper transistor control signal to control the on / off state of the power upper transistor, the power upper transistor control signal having a first level state and a second level state; wherein: in buck mode, the voltage difference across the power upper transistor is adjusted by adjusting the value of the first level state of the power upper transistor control signal.

[0006] According to an embodiment of the present invention, a control circuit for a BOOST circuit is provided, comprising: an upper-side control circuit, providing an upper-side control signal to control the on / off state of the power upper-side transistor of the BOOST circuit, the upper-side control signal having a first level state and a second level state; wherein: in normal mode, the value of the first level state of the upper-side control signal is fixed; and in buck mode, the voltage difference across the power upper-side transistor is adjusted by adjusting the value of the first level state of the upper-side control signal.

[0007] In one embodiment, the control circuit of the aforementioned BOOST circuit further includes: a first switch coupled between the input terminal of the BOOST circuit and the body terminal of the power transistor, wherein the first switch is off in normal mode and on in buck mode; and a second switch coupled between the body terminal of the power transistor and the output terminal of the BOOST circuit, wherein the second switch is on in normal mode and off in buck mode.

[0008] In one embodiment, the aforementioned upper-side control circuit includes: a buck turn-on control signal generation circuit that outputs a buck turn-on control signal; and a signal selection circuit that outputs an upper-side control signal based on the buck turn-on control signal, the upper-side pre-control signal, and a mode control signal; wherein the mode control signal represents a normal mode and a buck mode, wherein: in the normal mode, the upper-side pre-control signal is output as the upper-side control signal; and in the buck mode, the logical operation result of the buck turn-on control signal and the upper-side pre-control signal is output as the upper-side control signal, wherein the buck turn-on control signal controls the turn-on of the power upper-side, and the upper-side pre-control signal controls the turn-off of the power upper-side.

[0009] According to an embodiment of the present invention, a control method for a BOOST circuit is provided, comprising: comparing the input voltage VIN and the output voltage VOUT of the BOOST circuit; when the input voltage VIN is less than the output voltage VOUT, causing the BOOST circuit to operate in a normal mode, otherwise operating in a buck mode; in the normal mode, coupling the body terminal of the power transistor of the BOOST circuit to the input terminal of the BOOST circuit; in the normal mode, providing a power transistor control signal to control the on / off state of the power transistor of the BOOST circuit, wherein the values ​​of a first level state and a second level state of the power transistor control signal are fixed; in the buck mode, coupling the body terminal of the power transistor of the BOOST circuit to the output terminal of the BOOST circuit; in the buck mode, providing a power transistor control signal to control the on / off state of the power transistor of the BOOST circuit, and adjusting the voltage difference across the power transistor by adjusting the first level state of the power transistor control signal, wherein the value of the second level state of the power transistor control signal is fixed.

[0010] In one embodiment, the control method of the aforementioned BOOST circuit, wherein adjusting the voltage difference across the power transistor by adjusting the first level state of the upper transistor control signal includes: the value of the first level state of the upper transistor control signal decreases as the load of the BOOST circuit increases. Attached Figure Description

[0011] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings:

[0012] Figure 1 This is a schematic diagram of a typical BOOST circuit 100.

[0013] Figure 2 This is a schematic diagram of the circuit structure of a BOOST circuit 200 according to an embodiment of this application;

[0014] Figure 3 This is a schematic diagram of the signal waveform of a BOOST circuit 200 according to an embodiment of the present invention;

[0015] Figure 4 This is a schematic diagram of the circuit structure of the upper transistor control circuit 400 according to an embodiment of the present invention;

[0016] Figure 5 This is a schematic diagram of the circuit structure of the upper transistor control signal 500 according to an embodiment of the present invention;

[0017] Figure 6 This is a flowchart illustrating a control method 600 for a BOOST circuit according to an embodiment of this application. Detailed Implementation

[0018] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, materials, or methods have not been specifically described to avoid obscuring the invention.

[0019] The terms "first," "second," etc., used in the following description are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature specified with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0020] In this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the term "coupled" can refer to a method of electrical connection for signal transmission. "Coupled" can be a direct electrical connection or an indirect electrical connection through an intermediate medium.

[0021] Figure 2 This is a schematic diagram of the circuit structure of a BOOST circuit 200 according to an embodiment of this application. Figure 2 As shown, the BOOST circuit 200 includes: a high-power transistor P1, a low-power transistor P2, an inductor L1, and a control circuit 204. The high-power transistor P1 and the low-power transistor P2 are connected in series between the output terminal 203 of the BOOST circuit 200 and the reference ground GND. The high-power transistor P1 and the low-power transistor P2 are both coupled to the switching node 202, and the high-power transistor P1 provides an output voltage VOUT to the output terminal 203 of the BOOST circuit 200. The inductor L1 is coupled between the input terminal 201 and the switching node 202, storing or releasing energy as the high-power transistor P1 and the low-power transistor P2 are switched on and off. The control circuit 204 includes a high-power transistor control circuit 241, which provides a high-power transistor control signal GHF to control the switching on and off of the high-power transistor P1. The upper MOSFET control circuit 241 receives the upper MOSFET pre-control signal GH, the buck conduction control signal VRL, and the mode judgment signal CTR1, and outputs the upper MOSFET control signal GHF based on the upper MOSFET pre-control signal GH, the buck conduction control signal VRL, and the mode judgment signal CTR1.

[0022] The upper-level control signal GHF has a first level state and a second level state. The first level state of the upper-level control signal GHF corresponds to the conduction of the power upper-level transistor P1, and the second level state corresponds to the deactivation of the power upper-level transistor P1. Figure 2 In this embodiment, the power transistor P1 is a P-type transistor, and the first level state of the power transistor control signal GHF refers to a low level state, and the second level state refers to a high level state. In other embodiments, for example, when the power transistor P1 is an N-type transistor, the first level state of the power transistor control signal GHF refers to a high level state, and the second level state refers to a low level state.

[0023] exist Figure 2 In this embodiment, the mode determination signal CTR1 is generated based on the input voltage VIN and the output voltage VOUT. When the input voltage VIN is less than the output voltage VOUT, the BOOST circuit operates in normal mode, and the upper MOSFET pre-control signal GH acts as the upper MOSFET control signal GHF to control the on / off state of the power upper MOSFET P1. When the input voltage VIN is greater than the output voltage VOUT, the BOOST circuit operates in buck mode. The first level state of the upper MOSFET control signal GHF is related to the buck turn-on control signal VRL, and the second level state of the upper MOSFET control signal GHF is determined by the upper MOSFET pre-control signal GH. In one embodiment, in both normal and buck modes, the turn-off of the power upper MOSFET P1 is controlled by the upper MOSFET pre-control signal GH. In normal mode, the turn-on of the power upper MOSFET P1 is controlled by the upper MOSFET pre-control signal GH. In buck mode, the turn-on of the power upper MOSFET P1 is controlled by the buck turn-on control signal VRL.

[0024] exist Figure 2 In this embodiment, the control circuit 204 further includes a first switch S1 and a second switch S2. The first switch S1 is coupled between the input terminal 201 of the BOOST circuit 200 and the body terminal of the power transistor P1. The second switch S2 is coupled between the body terminal of the power transistor P1 and the output terminal 203 of the BOOST circuit 200. In normal mode, the first switch S1 is off and the second switch S2 is on. In buck mode, the first switch S1 is on and the second switch S2 is off. That is, in normal mode, the body terminal of the power transistor P1 is coupled to the output terminal 203 through the second switch S2, and the voltage at the body terminal is substantially the same as the output voltage VOUT. The body diode of the power transistor P1 behaves as... Figure 2 In the connection method, diode D1 is coupled with its anode to the input voltage VIN and its cathode to the output voltage VOUT. When the input voltage VIN is less than the output voltage VOUT, diode D1 is cut off, meaning the body diode of the power transistor P1 is also cut off. In buck mode, the body terminal of the power transistor P1 is coupled to the input terminal 201 through the first switch S1. The voltage at the body terminal is essentially the same as the input voltage VIN, and the body diode of the power transistor P1 behaves as follows: Figure 2In the connection configuration, diode D2's anode is coupled to the output voltage VOUT, and its cathode is coupled to the input voltage VIN. When the output voltage VOUT is less than the input voltage VIN, diode D2 is cut off, meaning the body diode of the power transistor P1 is also cut off. It should be understood that diodes D1 and D2 are symbolic representations of the body diode of the power transistor P1 and do not represent diodes independent of P1.

[0025] The first switch S1 and the second switch S2 are controlled by the mode judgment signal CTR1. Specifically, when the mode judgment signal CTR1 represents the normal mode, that is, the input voltage VIN is less than the output voltage VOUT, the first switch S1 is turned off and the second switch S2 is turned on; when the mode judgment signal CTR1 represents the buck mode, that is, the output voltage VOUT is less than the input voltage VIN, the first switch S1 is turned on and the second switch S2 is turned off. Figure 2 In this embodiment, the mode judgment signal CTR1 is used to control the second switch S2. The mode judgment signal CTR1, after passing through inverter N1, generates an inverted signal CTR2 to control the first switch S1, indicating that the first switch S1 and the second switch S2 are alternately on and off. In one embodiment, the first switch S1 and the second switch S2 include P-type transistors. When the mode judgment signal CTR1 is low, it indicates that the input voltage VIN is less than the output voltage VOUT, the BOOST circuit 200 operates in normal mode, the first switch S1 is off, and the second switch S2 is on. When the mode judgment signal CTR1 is high, it indicates that the input voltage VIN is greater than the output voltage VOUT, the BOOST circuit 200 operates in buck mode, the first switch S1 is on, and the second switch S2 is off. It should be understood that the on / off state of the first switch S1 and the second switch S2 is related to the type of the first switch S1 and the second switch S2 and the level state of the mode judgment signal CTR1. Those skilled in the art can select the switch type and signal level state according to the actual application.

[0026] Figure 3 This is a schematic diagram of the signal waveform of a BOOST circuit 200 according to an embodiment of the present invention. The following will be combined with... Figure 2 and Figure 3 This section explains the working principle of the BOOST circuit 200.

[0027] exist Figure 3 In this embodiment, when the input voltage VIN is less than the output voltage VOUT, the BOOST circuit 200 operates in normal mode. At this time, the lower MOSFET control signal GL controls the on / off state of the lower power MOSFET P2, and the upper MOSFET pre-control signal GH controls the on / off state of the upper power MOSFET P1. The upper power MOSFET P1 and the lower power MOSFET P2 are alternately switched on and off. Figure 3In this embodiment, the upper power transistor P1 is a P-type transistor, and the lower power transistor is an N-type transistor. Correspondingly, a high level of the lower transistor control signal GL corresponds to the conduction of the lower power transistor P2, and a low level corresponds to its turn-off; a low level of the upper transistor pre-control signal GH corresponds to the conduction of the upper power transistor P1, and a high level corresponds to its turn-off. The waveforms of the upper transistor control signal GH and the upper transistor pre-control signal GH are identical. When the lower power transistor P2 is on and the upper power transistor P1 is off, the input terminal 201 charges the inductor L1, increasing the inductor current IL, and the inductor L1 stores energy. When the lower power transistor P2 is off and the upper power transistor P1 is on, the inductor L1 provides energy to the output terminal 203, and the inductor current IL decreases. When the load increases, the conduction time of the lower power transistor P2 increases, and the conduction time of the upper power transistor P1 decreases, to release more energy to the load.

[0028] like Figure 3 As shown, when the input voltage VIN is greater than the output voltage VOUT, the BOOST circuit 200 operates in buck mode. The high level state of the upper transistor control signal GHF is consistent with the upper transistor pre-control signal GH, and the low level state is controlled by the buck conduction control signal VRL. The buck conduction control signal VRL makes the power upper transistor P1 in a slightly conducting state, thereby controlling the voltage difference VSW-VOUT across the power upper transistor P1 and reducing the loss of the power upper transistor P1.

[0029] In existing technology, when the BOOST circuit is in buck mode, the body diode of the power transistor is turned on, fixing the voltage difference across the power transistor at the forward voltage drop of the body diode, which is approximately 0.7V. In this case, the conduction loss of the power transistor increases, reducing the efficiency of the BOOST circuit. Figure 2 In this embodiment, in buck mode, the body terminal of the power transistor P1 is connected to the input voltage VIN by the first switch S1, thereby blocking the body diode D2 of the power transistor P1 in reverse, preventing the voltage across the power transistor P1 from being reduced to the diode's forward voltage drop. The voltage difference VSW-VOUT across the power transistor P1 is controlled by the buck turn-on control signal VRL. By controlling this voltage difference and adjusting it to be less than the diode's forward voltage drop, the losses of the power transistor P1 can be reduced. Furthermore, the smaller this voltage difference is adjusted, the less loss the power transistor P1 experiences.

[0030] Figure 4 This is a schematic diagram of the circuit structure of an upper-side MOSFET control circuit 400 according to an embodiment of the present invention. This upper-side MOSFET control circuit 400 can be applied to... Figure 2 The BOOST circuit 200 in this embodiment. (e.g.) Figure 4As shown, the upper MOSFET control circuit 400 includes a buck turn-on control signal generation circuit 421 and a signal selection circuit 422. The buck turn-on control signal generation circuit 421 outputs a buck turn-on control signal VRL to characterize the load of the BOOST circuit. The signal selection circuit 422 outputs an upper MOSFET control signal GHF based on the buck turn-on control signal VRL, the upper MOSFET pre-control signal GH, and the mode control signal CTR1.

[0031] exist Figure 4 In this embodiment, the buck turn-on control signal VRL is related to the load of the BOOST circuit. When the load of the BOOST circuit increases, the value of the buck turn-on control signal VRL decreases; when the load of the BOOST circuit decreases, the value of the buck turn-on control signal VRL increases. The buck turn-on control signal generation circuit 421 includes a resistor unit R1 and a current source circuit I1. The resistor unit R1 has a first terminal that receives the input voltage VIN, and a second terminal that is coupled to the first terminal of the current source circuit I1. The second terminal of the current source circuit I1 is coupled to the reference ground GND. The current of the current source circuit I1 flows through the resistor unit R1, generating a voltage drop I1×R1 across the resistor unit, thereby making the buck turn-on control signal VRL = VIN - I1×R1. Thus, the magnitude of the buck turn-on control signal VRL can be controlled by the resistance value of the resistor unit R1, thereby controlling the voltage drop and power consumption of the power transistor P1 in buck mode. Similarly, the magnitude of the buck turn-on control signal VRL can also be controlled by controlling the current value of the current source circuit I1. It should be understood that in other embodiments, the connection positions of the resistor unit R1 and the current source circuit I1 can be interchanged.

[0032] exist Figure 4 In this embodiment, the value of the current source circuit I1 is further related to the load of the BOOST circuit, and the load of the BOOST circuit is characterized by the load current IRL. When the load current IRL increases, the buck converter turn-on control signal VRL decreases; when the load current IRL decreases, the buck converter turn-on control signal VRL increases. The load current IRL can be obtained by current detection methods in the prior art, such as by detecting the inductor current IL, or by detecting the current of the power transistor (either the upper or lower MOSFET). In some embodiments, the load current IRL can also be replaced by other signals reflecting the load, such as a power signal. In some embodiments, the current provided by the current source circuit I1 can be fixed.

[0033] when Figure 4 The upper-side control circuit 400 in the embodiment is applied to Figure 2In the BOOST circuit 200 shown, the value of the buck converter control signal VRL decreases as the load increases. When the BOOST circuit 200 is in buck mode, the smaller the value of the buck converter control signal VRL, the smaller the switching voltage VSW, thereby reducing the voltage difference across the power transistor P1 and reducing the power consumption of the power transistor P1. In other words, when the BOOST circuit 200 is under heavy load, the power transistor control circuit 400 can further reduce the power of the power transistor P1.

[0034] The signal selection circuit 422 includes a logic gate circuit A1 and a selection circuit 422A. Logic gate circuit A1 has a first input terminal receiving the mode judgment signal CTR1, a second input terminal receiving the upper-side pre-control signal GH, and an output terminal outputting the selection signal SEL. Selection circuit 422A has a first input terminal receiving the upper-side pre-control signal GHF, a second input terminal receiving the buck converter turn-on control signal VRL, a control terminal receiving the selection signal SEL, and an output terminal providing the upper-side control signal GHF. The mode control signal CTR1 represents the normal mode and the buck converter mode. Figure 4 In this embodiment, logic gate circuit A1 includes an AND gate circuit. When the mode control signal CTR1 is low, it represents the normal mode; when it is high, it represents the buck mode. When the mode control signal CTR1 is low, the BOOST circuit operates in the normal mode, the selection signal SEL output by logic gate circuit A1 is low, and the selection circuit 422A selects the output upper-side pre-control signal GH as the upper-side control signal GHF. When the mode control signal CTR1 is high, the BOOST circuit operates in buck mode. In this mode: if the upper MOSFET pre-control signal GH is high, the selection signal SEL output by logic gate A1 is low, and selection circuit 422 selects the output upper MOSFET pre-control signal GH as the upper MOSFET control signal GHF. That is, in buck mode, the high-level value of the upper MOSFET control signal GHF is the same as the value of the upper MOSFET pre-control signal GH. If the upper MOSFET pre-control signal GH is low, the selection signal SEL output by logic gate A1 is high, and selection circuit 422 selects the output buck turn-on control signal VRL as the upper MOSFET control signal GHF. That is, in buck mode, the low-level value of the upper MOSFET control signal GHF is the same as the value of the buck turn-on control signal VRL. It should be understood that the high and low levels of the upper MOSFET control signal GHF refer to a relative state, not a state corresponding to the power supply voltage or reference ground voltage.

[0035] It should be understood that the high and low level states of the upper transistor control signal GHF are related to the fact that the power upper transistor of the BOOST circuit 200 is a P-type transistor. In other embodiments, when the power upper transistor is an N-type transistor, the high and low level states of the upper transistor control signal GHF are exactly the opposite. Those skilled in the art can adjust the levels and control methods of the corresponding signals according to the actual application needs under the guidance of this specification.

[0036] exist Figure 4 In this embodiment, by adjusting the resistance value of resistor unit R1, the value of the buck converter control signal VRL can be adjusted, thereby optimizing the power loss of the power transistor P1. Furthermore, in Figure 4 In this embodiment, the load current IRL controls the value of the buck converter turn-on control signal VRL by controlling the value flowing through the resistor unit R1, thereby enabling the power transistor P1 of the BOOST circuit to have lower power loss under heavy load. In some embodiments, the current value of the current source circuit I1 can be fixed.

[0037] Figure 5 This is a schematic diagram of the circuit structure of the upper MOSFET control signal 500 according to an embodiment of the present invention. This upper MOSFET control circuit 500 can be applied to... Figure 2 The BOOST circuit 200 in this embodiment. (e.g.) Figure 5 As shown, the upper MOSFET control circuit 500 includes a buck turn-on control signal generation circuit 421 and a signal selection circuit 522. The buck turn-on control signal generation circuit 421 outputs a buck turn-on control signal VRL to characterize the load of the BOOST circuit. The signal selection circuit 522 outputs an upper MOSFET control signal GHF based on the buck turn-on control signal VRL, the upper MOSFET pre-control signal GH, and the mode control signal CTR1.

[0038] exist Figure 5 In this embodiment, the signal selection circuit 522 includes a first selection circuit 522B and a second selection circuit 522C. The first selection circuit 522B has a first terminal receiving a buck turn-on control signal VRL, a second terminal receiving a fixed-level signal VS, a control terminal receiving an upper-side pre-control signal GH, and an output terminal providing a buck mode control signal VDM. The second selection circuit 522C has a first terminal receiving the upper-side pre-control signal GH, a second terminal receiving the buck mode control signal VRL, a control terminal receiving a mode judgment signal CTR1, and an output terminal providing an upper-side control signal GHF. The mode control signal CTR1 represents the normal mode and the buck mode.

[0039] exist Figure 5In this embodiment, the fixed-level signal VS is high, which can be, for example, the power supply voltage or any other voltage value used to turn off the power transistor P1. When the power transistor pre-control signal GH is high, the fixed-level signal VS is output as the buck mode control signal VDM; when the power transistor pre-control signal GH is low, the buck turn-on control signal VRL is output as the buck mode control signal VDM, thereby making the waveform of the buck mode control signal VDM similar to... Figure 3 In the embodiment, the upper tube control signal GHF is the same in buck mode.

[0040] The second selection circuit 522C is controlled by the mode control signal CTR1. When the mode control signal CTR1 is low, the BOOST circuit operates in normal mode, and the second selection circuit 522C selects the output upper MOSFET pre-control signal GH as the upper MOSFET control signal GHF. That is, in normal mode, the upper MOSFET control signal GHF is the same as the upper MOSFET pre-control signal GH. When the mode control signal CTR1 is high, the BOOST circuit operates in buck mode, and the second selection circuit 522C selects the output buck mode control signal VDM as the upper MOSFET control signal GHF. That is, in buck mode, the upper MOSFET control signal GHF is the same as the buck mode control signal VDM.

[0041] It should be understood that the high and low level states of the upper transistor control signal GHF are related to the use of a P-type transistor in the power upper transistor of the BOOST circuit 200. In other embodiments, when an N-type transistor is used in the power upper transistor, the high and low level states of the upper transistor control signal GHF are exactly the opposite. For example, the fixed level signal VS can be low, such as the reference ground voltage or any other voltage value used to turn off the power upper transistor P1. When the upper transistor pre-control signal GH is low, the fixed level signal VS is output as the buck mode control signal VDM; when the upper transistor pre-control signal GH is high, the buck turn-on control signal VRL is output as the buck mode control signal VDM, so that the waveform of the final buck mode control signal VDM can be used as the upper transistor control signal GHF in buck mode to control the on / off state of the power upper transistor P1. Those skilled in the art can adjust the levels and control methods of the corresponding signals according to the actual application needs under the guidance of this specification.

[0042] exist Figure 5 In this embodiment, by adjusting the resistance value of resistor unit R1, the value of the buck converter control signal VRL can be adjusted, thereby optimizing the power loss of the power transistor P1. Furthermore, in Figure 5 In this embodiment, the load current IRL controls the value of the buck converter turn-on control signal VRL by controlling the value flowing through the resistor unit R1, thereby enabling the power transistor P1 of the BOOST circuit to have lower power loss under heavy load. In some embodiments, the current value of the current source circuit I1 can be fixed.

[0043] exist Figure 4 and Figure 5 In this embodiment, the buck conduction control signal generation circuit 421 is merely illustrative. In other embodiments, the buck conduction control signal generation circuit 421 may be omitted, and the buck conduction control signal VRL may be provided by other variable voltage sources or controlled by other circuits.

[0044] The control circuit 204 of the BOOST circuit 200 in this embodiment can be integrated into a single chip, or integrated into a single chip with either or both of the power upper transistor P1 and the power lower transistor P2.

[0045] In this embodiment, the upper power transistor P1 is a P-type power transistor. In other embodiments, the BOOST circuit may also use an N-type power transistor. Generally, the lower power transistor P2 is an N-type power transistor. In some embodiments, a P-type power transistor may also be used as the lower power transistor P2.

[0046] In this embodiment, the upper MOSFET pre-control signal GH and the lower MOSFET control signal GL are complementary signals. The upper MOSFET pre-control signal GH and the lower MOSFET control signal GL can be generated via an external PWM signal or through the chip's internal circuitry. This internal circuitry can employ any known loop control mode, such as peak current control mode, voltage control mode, or constant on (off) time mode control.

[0047] Figure 6 This is a flowchart illustrating a control method 600 for a BOOST circuit according to an embodiment of this application. The BOOST circuit may include, for example: Figure 2 The BOOST circuit 200 is shown. (As shown) Figure 6 The control method 600 includes steps 601-605.

[0048] In step 601, the input voltage VIN and output voltage VOUT of the BOOST circuit are compared. When the input voltage VIN is less than the output voltage VOUT, the BOOST circuit is set to operate in normal mode and the process jumps to step 602. Otherwise, it operates in buck mode and the process jumps to step 604.

[0049] In step 602, the body terminal of the power transistor of the BOOST circuit is coupled to the input terminal of the BOOST circuit.

[0050] In step 603, an upper-side control signal is provided to control the on / off state of the power upper-side transistor of the BOOST circuit, wherein the values ​​of the first level state and the second level state of the upper-side control signal are fixed.

[0051] In step 604, the body terminal of the power transistor of the BOOST circuit is coupled to the output terminal of the BOOST circuit.

[0052] In step 605, an upper transistor control signal is provided to control the on / off state of the power upper transistor, and the voltage difference across the power upper transistor is adjusted by adjusting the first level state of the upper transistor control signal, wherein the value of the second level state of the upper transistor control signal is fixed.

[0053] In one embodiment, in buck mode, the value of the first level state of the upper MOSFET control signal decreases as the load on the BOOST circuit increases.

[0054] In one embodiment, step 605 includes: providing an adjustable buck turn-on control signal; outputting an upper MOSFET control signal based on the buck turn-on control signal, an upper MOSFET pre-control signal, and a mode control signal, wherein the mode control signal represents a normal mode and a buck mode; in the buck mode, the buck turn-on control signal controls the turn-on of the power upper MOSFET, and the upper MOSFET pre-control signal controls the turn-off of the power upper MOSFET.

[0055] In one embodiment, a buck turn-on control signal is generated by supplying current to a resistor unit, and the buck turn-on control signal is adjusted by adjusting the resistance value of the resistor unit.

[0056] In one embodiment, a buck turn-on control signal is generated by supplying current to the resistor unit, and the buck turn-on control signal is adjusted by adjusting the value of the current.

[0057] In one embodiment, the current flowing through the resistor unit is related to the load of the BOOST circuit, the correlation including the current flowing through the resistor unit decreasing as the load of the BOOST circuit increases, and the current flowing through the resistor unit increasing as the load of the BOOST circuit increases.

[0058] In one embodiment, the buck conduction control signal characterizes the load of the BOOST circuit.

[0059] In one embodiment, the value of the buck turn-on control signal decreases as the load on the BOOST circuit increases.

[0060] It should be understood that the high and low levels of the signals in the above embodiments are set in accordance with the type of transistor in the embodiments. In other embodiments, when the transistor type changes, the level form of the corresponding control signal will also change accordingly.

[0061] The above description is merely a preferred embodiment of this application and is not intended to limit the application in any way. Although this application has disclosed preferred embodiments above, it is not intended to limit the application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall still fall within the protection scope of the technical solutions of this application.

Claims

1. A BOOST circuit, comprising: The upper and lower power transistors are connected in series between the output of the BOOST circuit and the reference ground. The upper and lower power transistors are both coupled to the switching node, and the upper power transistor provides the output voltage to the output of the BOOST circuit. as well as The upper transistor control circuit provides an upper transistor control signal to control the on / off state of the power upper transistor, and the upper transistor control signal has a first level state and a second level state; in: In buck mode, the voltage difference across the power transistor is adjusted by regulating the value of the first level state of the upper transistor control signal.

2. The BOOST circuit as described in claim 1, further comprising: The first switch is coupled between the input terminal of the BOOST circuit and the body terminal of the power transistor. The first switch is off in normal mode and on in buck mode. as well as The second switch is coupled between the body terminal of the power transistor and the output terminal of the BOOST circuit. The second switch is turned on in normal mode and turned off in buck mode.

3. The BOOST circuit as described in claim 1, wherein the upper MOSFET control circuit comprises: A step-down turn-on control signal generation circuit outputs a step-down turn-on control signal; The signal selection circuit outputs the upper MOSFET control signal based on the buck turn-on control signal, the upper MOSFET pre-control signal, and the mode control signal. The mode control signal represents the normal mode and the buck mode, wherein: In normal mode, the upper duct pre-control signal is output as the upper duct control signal; In buck mode, the logical operation result of the buck turn-on control signal and the upper MOSFET pre-control signal is output as the upper MOSFET control signal. The buck turn-on control signal controls the turn-on of the power upper MOSFET, and the upper MOSFET pre-control signal controls the turn-off of the power upper MOSFET.

4. The BOOST circuit as described in claim 3, wherein the buck conduction control signal generation circuit comprises: Resistor unit; as well as A current source circuit, connected in series with the resistor unit, is coupled between the input voltage and the reference ground, and the current source circuit provides a first current flowing through the resistor unit; in: The connection point between the resistor unit and the current source circuit provides the step-down conduction control signal.

5. The BOOST circuit of claim 4, wherein the first current is proportional to the load current of the BOOST circuit.

6. The BOOST circuit as claimed in claim 3, wherein the signal selection circuit comprises: The logic gate circuit has a first input terminal to receive the mode judgment signal, a second input terminal to receive the upper transistor pre-control signal, and an output terminal to output the selection signal; as well as The selection circuit has a first input terminal to receive the upper MOSFET pre-control signal, a second input terminal to receive the buck turn-on control signal, a control terminal to receive the selection signal, and an output terminal to provide the upper MOSFET control signal.

7. The BOOST circuit as claimed in claim 3, wherein the signal selection circuit comprises: The first selection circuit has a first terminal for receiving the buck turn-on control signal, a second terminal for receiving a fixed level signal, a control terminal for receiving the upper MOSFET pre-control signal, and an output terminal for providing a buck mode control signal. as well as The second selection circuit has a first terminal for receiving the upper MOSFET pre-control signal, a second terminal for receiving the buck mode control signal, a control terminal for receiving the mode judgment signal, and an output terminal for providing the upper MOSFET control signal.

8. The BOOST circuit according to any one of claims 1-7, wherein the power upper transistor comprises a P-type power transistor.

9. A control circuit for a BOOST circuit, comprising: The upper MOSFET control circuit provides an upper MOSFET control signal to control the on / off state of the power upper MOSFET of the BOOST circuit. The upper MOSFET control signal has a first level state and a second level state. in: In normal mode, the value of the first level state of the upper transistor control signal is fixed; and In buck mode, the voltage difference across the power transistor is adjusted by regulating the value of the first level state of the upper transistor control signal.

10. The control circuit of the BOOST circuit as described in claim 9, further comprising: The first switch is coupled between the input terminal of the BOOST circuit and the body terminal of the power transistor. The first switch is off in normal mode and on in buck mode. as well as The second switch is coupled between the body terminal of the power transistor and the output terminal of the BOOST circuit. The second switch is turned on in normal mode and turned off in buck mode.

11. The control circuit of the BOOST circuit as described in claim 9, wherein the upper transistor control circuit comprises: A step-down turn-on control signal generation circuit outputs a step-down turn-on control signal; The signal selection circuit outputs the upper MOSFET control signal based on the buck turn-on control signal, the upper MOSFET pre-control signal, and the mode control signal. The mode control signal represents the normal mode and the buck mode, wherein: In normal mode, the upper duct pre-control signal is output as the upper duct control signal; In buck mode, the logical operation result of the buck turn-on control signal and the upper MOSFET pre-control signal is output as the upper MOSFET control signal. The buck turn-on control signal controls the turn-on of the power upper MOSFET, and the upper MOSFET pre-control signal controls the turn-off of the power upper MOSFET.

12. The control circuit of the BOOST circuit as described in claim 11, wherein the step-down conduction control signal generation circuit comprises: Resistor unit; as well as A current source circuit, connected in series with the resistor unit, is coupled between the input voltage and the reference ground, and the current source circuit provides a first current flowing through the resistor unit; in: The connection point between the resistor unit and the current source circuit provides the step-down conduction control signal.

13. The control circuit of the BOOST circuit as claimed in claim 12, wherein the first current is proportional to the load current of the BOOST circuit.

14. The control circuit of the BOOST circuit as described in claim 11, wherein the signal selection circuit comprises: The logic gate circuit has a first input terminal to receive the mode judgment signal, a second input terminal to receive the upper transistor pre-control signal, and an output terminal to output the selection signal; as well as The selection circuit has a first input terminal to receive the upper MOSFET pre-control signal, a second input terminal to receive the buck turn-on control signal, a control terminal to receive the selection signal, and an output terminal to provide the upper MOSFET control signal.

15. The control circuit of the BOOST circuit as claimed in claim 11, wherein the signal selection circuit comprises: The first selection circuit has a first terminal for receiving the buck turn-on control signal, a second terminal for receiving a fixed level signal, a control terminal for receiving the upper MOSFET pre-control signal, and an output terminal for providing a buck mode control signal. as well as The second selection circuit has a first terminal for receiving the upper MOSFET pre-control signal, a second terminal for receiving the buck mode control signal, a control terminal for receiving the mode judgment signal, and an output terminal for providing the upper MOSFET control signal.

16. A control method for a BOOST circuit, comprising: Compare the input voltage VIN and output voltage VOUT of the BOOST circuit. When the input voltage VIN is less than the output voltage VOUT, the BOOST circuit operates in normal mode; otherwise, it operates in buck mode. In normal mode, the body terminal of the power transistor of the BOOST circuit is coupled to the input terminal of the BOOST circuit. In normal mode, a power transistor control signal is provided to control the on / off state of the power transistor in the BOOST circuit, and the values ​​of the first level state and the second level state of the power transistor control signal are fixed. In buck mode, the body terminal of the power transistor in the BOOST circuit is coupled to the output terminal of the BOOST circuit. In buck mode, an upper-side control signal is provided to control the on / off state of the power upper-side transistor in the BOOST circuit, and the voltage difference across the power upper-side transistor is adjusted by adjusting the first level state of the upper-side control signal, while the value of the second level state of the upper-side control signal is fixed.

17. The control method for the BOOST circuit as described in claim 16, wherein adjusting the voltage difference across the power transistor by adjusting the first level state of the upper transistor control signal comprises: The value of the first level state of the upper control signal decreases as the load on the BOOST circuit increases.

18. The control method for the BOOST circuit as described in claim 16, wherein adjusting the voltage difference across the power transistor by adjusting the first level state of the upper transistor control signal comprises: A buck turn-on control signal is generated by supplying current to the resistor unit, and the buck turn-on control signal is adjusted by adjusting the resistance value of the resistor unit.

19. The control method for the BOOST circuit as described in claim 16, wherein adjusting the voltage difference across the power transistor by adjusting the first level state of the upper transistor control signal includes: A buck turn-on control signal is generated by supplying current to the resistor unit, and the buck turn-on control signal is adjusted by adjusting the value of the current.

20. The control method for the BOOST circuit as described in claim 16, wherein the buck conduction control signal characterizes the load of the BOOST circuit.

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