Power conversion circuit

Abstract

The invention provides a power conversion circuit. The power conversion circuit comprises a first input circuit, a second input circuit, a linear voltage regulator, a switch and a switch control circuit, the first input circuit receives a first input voltage through a first input end, the second input circuit receives a second input voltage through a second input end, and the first input voltage is larger than the second input voltage. The linear voltage regulator receives the first input voltage or the second input voltage to output an output voltage. The switch has a first end coupled to the first input circuit and a second end coupled to the second input circuit and the linear voltage regulator. The switch control circuit receives a second input voltage and outputs a control signal to open the switch when the second input voltage reaches a predetermined level, so that the linear regulator outputs the output voltage according to the second input voltage.

Description

Technical Field

[0001] The present invention relates to a power conversion circuit, and more particularly to a power conversion circuit with intelligent efficiency. Background Art

[0002] Energy consumption and power conversion efficiency are both indispensable design considerations in electronic products and are thus subject to many regulations, such as the Energy Star label or the European Union's Energy-Related Product (ErP) directive.

[0003] For example, linear voltage regulators are often used for voltage conversion. If the voltage difference between the input and output of the above linear voltage regulator is too large, it will generate a large amount of energy consumption, which will prevent the electronic product from meeting the regulatory restrictions. Therefore, a new solution is needed to overcome the above problems. Summary of the Invention

[0004] The term "embodiment" and similar terms, such as "implementation", "configuration", "aspect", "example", and "option", are intended to refer broadly to all subject matter of this disclosure and the following claims. Statements that include these terms should be understood not to be limited to the subject matter described herein or to be used to limit the meaning or scope of the following claims. The embodiments covered by this disclosure are defined by the following claims, not by the present invention content. The present invention content is a high-level overview of the various aspects of the disclosure and introduces some concepts that will be further described in the implementation. The present invention content is not used to identify the key or essential features of the claim subject matter. The present invention content should not be used alone to determine the scope of the claim subject matter. The subject matter should be understood in reference to the appropriate portions of the entire detailed description of this disclosure, any or all of the drawings, and each claim.

[0005] Embodiments of the present disclosure provide a power conversion circuit, including a first input circuit, a second input circuit, a linear voltage regulator, a switch, and a switch control circuit. The first input circuit receives a first input voltage through a first input terminal, and the second input circuit receives a second input voltage through a second input terminal, where the first input voltage is greater than the second input voltage. The linear voltage regulator receives the first input voltage or the second input voltage to output an output voltage. A first end of the switch is coupled to the first input circuit, and a second end of the switch is coupled to the second input circuit and the linear voltage regulator. The switch control circuit receives the second input voltage and, when the second input voltage reaches a predetermined level, outputs a control signal to open the switch, so that the linear voltage regulator outputs the output voltage according to the second input voltage. Brief Description of the Drawings

[0006] The present disclosure, the advantages thereof, and the drawings will be more readily understood from the following description of representative embodiments and reference to the accompanying drawings. These drawings only depict representative embodiments and should not be construed as limiting various embodiments or claims.

[0007] Figure 1 It is a schematic diagram of a power conversion circuit 100 described according to the present disclosure.

[0008] Figure 2 It is a schematic diagram of a power conversion circuit 200 described according to the present disclosure.

[0009] Figure 3 It is a schematic diagram of a power conversion circuit 300 described according to the present disclosure.

[0010] Figure 4 It is a schematic diagram of a power conversion circuit 400 described according to the present disclosure.

[0011]

Symbol Description

[0012] 100, 200, 300, 400: Power conversion circuit

[0013] 102, 202, 302: Switch

[0014] 110, 120, 130: Input circuit

[0015] 140, 240, 340, 440: Switch control circuit

[0016] 150, 250, 350, 450: Linear voltage regulator

[0017] 260, 360, 460: Voltage conversion circuit

[0018] 340a, 440a: Detection circuit

[0019] 340b, 440b: Control circuit

[0020] Input1, Input2, Vin: Input voltage

[0021] Vout: Output voltage

[0022] Vctrl: Control signal

[0023] D1, D2, D3, D4, D5, D6, D7, D8, D9: Diode

[0024] V1: Enable signal

[0025] M1, M2, M3: Transistor

[0026] R1, R2, R3, R4, R5, R6: Resistors

[0027] C1: Capacitor

[0028] N1: First Node

[0029] N2: Second Node

[0030] N3: Third Node Detailed Implementation Manner

[0031] Multiple embodiments are described herein with reference to the accompanying drawings, in which like reference numerals are used to represent like or equivalent elements. The above drawings are not necessarily drawn to scale and are for illustrative purposes only to show the aspects and features of the present disclosure. A large number of specific details, relationships, and methods are set forth to provide a complete understanding of the specific aspects and features of the present disclosure. However, those of ordinary skill in the relevant technical field will understand that these aspects and features can be practiced without one or more of the above specific details, in other relationships, or using other methods. In some examples, well-known structures or operations are not shown in detail for illustrative purposes. The multiple embodiments disclosed herein are not necessarily limited to the order of actions or events illustrated. Some actions may occur in a different order and / or simultaneously with other actions or events. Further, not all actions illustrated are necessary to implement the specific aspects and features of the present disclosure.

[0032] For the convenience of detailed description herein, unless otherwise specified, the singular includes the plural and vice versa where appropriate. The word "comprising" means "including but not limited to". In addition, words used to indicate approximation, such as "about", "almost", "substantially", "approximately", and similar words, may be used herein to represent "within", "close to", "almost within", "within 3 - 5%", "within an acceptable manufacturing tolerance", or any logical combination thereof. Similarly, the words "vertical" or "horizontal" respectively additionally include "within 3 - 5% in the vertical or horizontal direction". In addition, words indicating direction, such as "top", "bottom", "left", "right", "above", and "below", mean the equivalent directions described in the reference drawings; the orientation should be understood based on the object or element being referenced, for example, based on the position where an object or element is commonly used; or according to other descriptions herein.

[0033] Figure 1 It is a schematic diagram of a power conversion circuit 100 described according to the present disclosure. For example, the power conversion circuit 100 can be used in electronic devices such as desktop computers or mobile devices, or other systems. Refer to Figure 1, the power conversion circuit 100 includes an input circuit 110, an input circuit 120, an input circuit 130, a switch 102, a switch control circuit 140, and a linear voltage regulator 150.

[0034] The input circuit 110 has a first input terminal for receiving an input voltage Input1 and a first output terminal coupled to the switch 102. In some embodiments, for example, the input voltage Input1 can be 19.5V, and the input voltage Input1 can be from a charger (such as an AC-DC transformer), but the present disclosure is not limited thereto. The input circuit 120 has a second input terminal for receiving an input voltage Input2 and a second output terminal coupled to the switch 102. In some embodiments, for example, the input voltage Input2 can be 20V, and the input voltage Input2 can be from a USB Type-C charger, but the present disclosure is not limited thereto. When the switch 102 is short-circuited, the input circuit 110 or the input circuit 120 can output the input voltage Input1 or the input voltage Input2 to the linear voltage regulator 150, so that the linear voltage regulator 150 outputs an output voltage Vout. In the embodiments of the present disclosure, both the input voltage Input1 and the input voltage Input2 are greater than the output voltage Vout. For example, the output voltage Vout can be 3.3V, but is not limited thereto. The conversion efficiency at this time is the output voltage of the linear voltage regulator 150 divided by the input voltage, that is, the output voltage Vout / the input voltage Input1 = 3.3 / 19.5 = 16.9%, or the output voltage Vout / the input voltage Input2 = 3.3 / 20 = 16.5%.

[0035] When the input voltage Input1 and / or the input voltage Input2 enter the system, they can be converted into multiple voltages inside the system, including an input voltage Vin. For example, the input voltage Vin can be 5V, but is not limited thereto. In certain embodiments, the input voltage Vin can also be 3.0V, 3.3V, 12V, but is not limited thereto. When the input voltage Vin is generated inside the system, the input circuit 130 can receive the input voltage Vin through a third input terminal. When the switch 102 is open, the connection between the linear voltage regulator 150 and the input circuit 110 and the input circuit 120 can be disconnected, so that the linear voltage regulator 150 only receives the input voltage Vin from a third output terminal of the input circuit 130. Then, the linear voltage regulator 150 converts the received input voltage Vin into the output voltage Vout. The conversion efficiency at this time is the output voltage Vout / the input voltage Vin = 3.3 / 5 = 66%.

[0036] One end of switch 102 is coupled to the first output of input circuit 110 and the second output of input circuit 120, and the other end of switch 102 is coupled to the third output of input circuit 130 and the input of linear voltage regulator 150. Switch 102 is configured to receive a control signal Vctrl from switch control circuit 140, where control signal Vctrl is used to open or short circuit switch 102. When input voltage Vin is received and input voltage Vin reaches a predetermined level (e.g., 5V), switch control circuit 140 outputs control signal Vctrl to switch 102 to open switch 102. However, when input voltage Vin does not exist (e.g., input voltage Vin is zero or does not reach a predetermined level (e.g., does not reach 5V)), switch control circuit 140 outputs control signal Vctrl to switch 102 to short circuit switch 102. At this time, the input voltage of linear voltage regulator 150 changes from input voltage Vin to input voltage Input1 or input voltage Input2. In some embodiments, when the input voltage reaches 5V, it is determined that input voltage Vin is established (or ready), and only then will switch control circuit 140 output control signal Vctrl to open switch 102. The above mechanism prevents switch 102 from opening when input voltage Vin has not reached a predetermined level (e.g., 5V), thereby avoiding input circuit 110 or input circuit 120 from disconnecting from linear voltage regulator 150 before input voltage Vin is established (or ready), resulting in input voltage Input1 or input voltage Input2 not being supplied to linear voltage regulator 150 and causing linear voltage regulator 150 to be unable to perform voltage conversion.

[0037] It should be noted that although, as Figure 1 shown, power conversion circuit 100 has input circuit 110 and input circuit 120, power conversion circuit 100 may also have only one of input circuit 110 and input circuit 120, or have two or more input circuits. That is, having only one of input voltage Input1 and input voltage Input2, or having more than two input voltages, can also enable power conversion circuit 100 to operate properly. In addition, for example, linear converter 150 can be a low dropout linear regulator (LDO), but is not limited thereto.

[0038] Figure 2 is a schematic diagram of a power conversion circuit 200 described according to the present disclosure. Similar to power conversion circuit 100, power conversion circuit 200 can be used in electronic devices such as desktop computers or mobile devices, or other systems. Refer to Figure 2, the power conversion circuit 200 includes a diode D1, a diode D2, a diode D3, a switch 202, a voltage conversion circuit 260, a switch control circuit 240, and a linear voltage regulator 250.

[0039] The diode D1 and the diode D2 are respectively similar to Figure 1 the input circuit 110 and the input circuit 120 in the power conversion circuit 100 of Figure 1 . The anode of the diode D1 is configured to receive the input voltage Input1, and the cathode is configured to be coupled to the switch 202. The anode of the diode D2 is configured to receive the input voltage Input2, and the cathode is configured to be coupled to the switch 202. When the switch 202 is short-circuited, the diode D1 or the diode D2 can output the input voltage Input1 or the input voltage Input2 to the linear voltage regulator 250, so that the linear voltage regulator 250 generates the output voltage Vout. Similar to

[0040] the power conversion circuit 100, the input voltage Input1 and the input voltage Input2 are both greater than the output voltage Vout. At this time, the conversion efficiency is the output voltage of the linear voltage regulator 250 divided by the input voltage, that is, the output voltage Vout / the input voltage Input1 = 3.3 / 19.5 = 16.9%, or the output voltage Vout / the input voltage Input2 = 3.3 / 20 = 16.5%.

[0041] One end of switch 202 is coupled to the cathodes of diodes D1 and D2, and the other end of switch 202 is coupled to the cathode of diode D3 and the input terminal of linear voltage regulator 250. Similar to power conversion circuit 100, switch control circuit 240 outputs a control signal Vctrl to switch 202 to open or short circuit switch 202. When the input voltage Vin is received by voltage conversion circuit 260 and the input voltage Vin reaches a predetermined level, switch control circuit 240 outputs the control signal Vctrl to switch 202 to open switch 202. However, when the input voltage Vin does not exist (e.g., the input voltage Vin is zero or does not reach a predetermined level), switch control circuit 240 outputs the control signal Vctrl to switch 202 to short circuit switch 202. At this time, the input voltage of linear voltage regulator 250 changes from input voltage Vin to input voltage Input1 or input voltage Input2. Similar to power conversion circuit 100, when the input voltage Vin is established or ready (e.g., reaches 5V), switch control circuit 240 outputs the control signal Vctrl to switch 202 to open switch 202. The above mechanism can prevent transistors D1 and D2 from disconnecting from linear voltage regulator 150 before the input voltage Vin is established, resulting in input voltage Input1 or input voltage Input2 not being supplied to linear voltage regulator 150 and linear voltage regulator 150 being unable to perform voltage conversion.

[0042] It should be noted that although, as Figure 2 shown, power conversion circuit 200 has diodes D1 and D2, power conversion circuit 200 may also have only one of diodes D1 and D2, or have two or more diodes as the input circuit. That is, having only one of input voltage Input1 and input voltage Input2, or having more than two input voltages, can also make power conversion circuit 200 operate normally. Additionally, although in Figure 2 voltage conversion circuit 260 is shown as being separate from switch control circuit 240, in some embodiments, voltage conversion circuit 260 may also be located within switch control circuit 240. Furthermore, for example, linear converter 250 can be an LDO, and voltage conversion circuit 260 can be a pulse width modulation converter, but is not limited thereto.

[0043] Figure 3 is a schematic diagram of a power conversion circuit 300 described according to the present disclosure. Similar to power conversion circuit 200, power conversion circuit 300 can be used in electronic devices such as desktop computers or mobile devices, or other systems. Referring to Figure 3, the power conversion circuit 300 includes a diode D4, a diode D5, a diode D6, a switch 302, a voltage conversion circuit 360, a switch control circuit 340, and a linear voltage regulator 350. Among them, the operations and connections of the diode D4, the diode D5, the diode D6, the switch 302, and the linear voltage regulator 350 are respectively similar to Figure 2 the operations of the diode D1, the diode D2, the diode D3, the switch 202, and the linear voltage regulator 250 in

[0044] For the sake of brevity and clarity, they will not be elaborated below. When the input voltage Input1 and / or the input voltage Input2 enter the system, they can be converted into multiple voltages inside the system, including the input voltage Vin obtained through the conversion by the voltage conversion circuit 360. Similar to the power conversion circuit 200, for example, the input voltage Vin can be 5V, but it is not limited to this.

[0045] The difference between the power conversion circuit 300 and the power conversion circuit 200 lies in the switch control circuit 340. Compared with the switch control circuit 240 in the power conversion circuit 200, the switch control circuit 340 further includes a detection circuit 340a and a control circuit 340b. When the voltage conversion circuit 360 generates the input voltage Vin, the voltage conversion circuit 360 can output the input voltage Vin to the anode of the diode D6 and the detection circuit 340a. After the detection circuit 340a receives the input voltage Vin and determines that the input voltage Vin reaches a predetermined level (such as 5V), it will generate an enabling signal V1 and output it to the control circuit 340b. After receiving the enabling signal V1, the control circuit 340b will output a control signal Vctrl to the switch 302 to open the switch 302. At this time, the linear voltage regulator disconnects the connection with the diodes D4 and D5, so that the linear voltage regulator 350 only receives the input voltage Vin from the cathode of the diode D6. Then, the linear voltage regulator 350 converts the input voltage Vin into an output voltage Vout, and the conversion efficiency here is output voltage Vout / input voltage Vin = 3.3 / 5 = 66%.

[0046] The control circuit 340b outputs a control signal Vctrl to the switch 302 to open or short-circuit the switch 302. When the self-detection circuit 340a receives the enable signal V1, the control circuit 340b outputs the control signal Vctrl to the switch 302 to open the switch 302. When the enable signal V1 does not exist (e.g., the detection circuit 340a does not receive the input voltage Vin, or the detection circuit 340a determines that the input voltage Vin has not reached a predetermined level), the control circuit 340b outputs the control signal Vctrl to the switch 302 to short-circuit the switch 302. At this time, the input voltage of the linear regulator 350 changes from the input voltage Vin to the input voltage Input1 or the input voltage Input2. Similar to the power conversion circuit 200, the above mechanism can prevent the transistors D4 and D5 from disconnecting from the linear regulator 150 before the input voltage Vin is established, resulting in the input voltage Input1 or the input voltage Input2 not being supplied to the linear regulator 150 and the linear regulator 150 being unable to perform voltage conversion.

[0047] It should be noted that although, as Figure 3 shown, the power conversion circuit 300 has the diodes D4 and D5, similar to the power conversion circuit 200, the power conversion circuit 300 may also have only one of the diodes D4 and D5, or have two or more diodes as the input circuit. That is, having only one of the input voltages Input1 and Input2, or having more than two input voltages, can also make the power conversion circuit 300 operate normally. Additionally, although in Figure 3 , the voltage conversion circuit 360 is shown as being separate from the switch control circuit 340, the voltage conversion circuit 360 may also be located within the switch control circuit 340. Furthermore, for example, the linear converter 350 may be an LDO, and the voltage conversion circuit 360 may be a pulse width modulation converter.

[0048] Figure 4 is a schematic diagram of a power conversion circuit 400 described according to the present disclosure. Similar to the power conversion circuit 300, the power conversion circuit 400 can be used in electronic devices such as desktop computers or mobile devices, or other systems. Referring to Figure 4 , the power conversion circuit 400 includes a diode D7, a diode D8, a diode D9, a transistor M1, a voltage conversion circuit 460, a switch control circuit 440, and a linear regulator 450. Among them, the operations and connections of the diode D7, the diode D8, the diode D9, and the linear regulator 450 are respectively similar to Figure 3 the operations of the diodes D4, D5, D6, and the linear regulator 350 in, so for the sake of simplicity and clarity, they will not be described in detail below.

[0049] After the input voltage Input1 and / or the input voltage Input2 enter the system, they can be converted into multiple voltages inside the system, including the input voltage Vin obtained through conversion by the voltage conversion circuit 460. For example, the input voltage Vin can be 5V, but is not limited thereto. Similar to the switch control circuit 340 in the power conversion circuit 300, the switch control circuit 440 also includes a detection circuit 440a and a control circuit 440b.

[0050] The detection circuit 440a includes a resistor R1, a resistor R2, a capacitor C1, and a transistor M2. As Figure 4 shown, the transistor M2 can be an N-type metal oxide semiconductor (NMOS) transistor, but is not limited thereto. In some embodiments, the transistor M2 can be any suitable switching element, such as a bipolar junction transistor (BJT), but is not limited thereto. The transistor M2 has a drain terminal coupled to a second node N2, a gate terminal coupled to a first node N1, and a source terminal coupled to a ground terminal. The resistor R1 is coupled between the voltage conversion circuit 460 and the first node N1, the resistor R2 is coupled between the first node N1 and the ground terminal, and the capacitor C1 is coupled between the first node N1 and the ground terminal. When the voltage conversion circuit 460 generates the input voltage Vin, the voltage conversion circuit 460 can output the input voltage Vin to the anode of the diode D9 and the detection circuit 440a. After receiving the input voltage Vin, the detection circuit 440a determines whether the input voltage Vin reaches a predetermined level (e.g., 5V). Appropriately adjusting the values of the resistor R1, the resistor R2, and the capacitor C1 can ensure that when the input voltage Vin reaches 5V, the detection circuit 440a generates an enabling signal V1 and outputs it to the control circuit 440b through the drain terminal of the transistor M2.

[0051] As Figure 4As shown, the control circuit 440b includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a transistor M3. Similar to transistor M2, transistor M3 can be an NMOS transistor or any suitable switching element. Transistor M3 has a gate terminal coupled to the second node N2, a drain terminal coupled to resistor R6, and a source terminal coupled to the ground terminal. Resistor R3 is coupled between the cathodes of diodes D7 and D8 and the second node N2. Resistor R5 is coupled between the source terminal of transistor M1 and a third node N3. Resistor R6 is coupled between the third node N3 and the drain terminal of transistor M3. The control circuit 440b outputs a control signal Vctrl to the gate terminal of transistor M1 after receiving an enabling signal V1 at the gate terminal of transistor M3. When transistor M1 is non-conductive, the linear regulator 450 disconnects from diodes D7 and D8, such that the linear regulator 450 receives only the input voltage Vin from the cathode of diode D9. The linear regulator 450 then converts the input voltage Vin into an output voltage Vout, with a conversion efficiency of output voltage Vout / input voltage Vin = 3.3 / 5 = 66%.

[0052] Continuing to refer to Figure 4 , transistor M1 has a source terminal coupled to the cathodes of diodes D7 and D8, a drain terminal coupled to the cathode of diode D9 and the input terminal of the linear regulator 450, and a gate terminal coupled to the third node N3. The control circuit 440b outputs a control signal Vctrl to the gate terminal of transistor M1 to control the conduction or non-conduction of transistor M1. When the enabling signal V1 is received from the detection circuit 440a, the control circuit 440b outputs a control signal Vctrl to the gate terminal of transistor M1 to render transistor M1 non-conductive. However, when the enabling signal V1 is absent (e.g., the detection circuit 440a does not receive the input voltage Vin or determines that the input voltage Vin does not reach a predetermined level), the control circuit 440b outputs a control signal Vctrl to the gate terminal of transistor M1 to render transistor M1 conductive. At this time, the input voltage of the linear regulator 450 changes from the input voltage Vin to the input voltage Input1 or the input voltage Input2.

[0053] Continuing to refer to Figure 4, the voltage conversion circuit 460 generates an input voltage Vin and outputs it to the anode of diode D9 and one end of resistor R1. By appropriately adjusting the values of resistor R1, resistor R2, and capacitor C1, when the input voltage Vin is established or ready (e.g., reaches 5V), a sufficient voltage division is established at the first node N1, causing transistor M2 to conduct and short-circuit the drain and source terminals of transistor M2. At this time, the voltage at the second node N2 is the voltage of the ground terminal. Therefore, transistor M3 does not conduct, making the drain and source terminals of transistor M3 equivalent to an open circuit and causing the voltage at the third node N3 to rise until the voltage at the third node N3 makes transistor M1 non-conductive, then the drain and source terminals of transistor M1 are equivalent to an open circuit. At this time, the voltage received at the input terminal of the linear regulator 450 is the input voltage Vin output by diode D9.

[0054] That is to say, the voltage conversion circuit 460 outputs the input voltage Vin to the anode of diode D9 and one end of resistor R1 (i.e., outputs the input voltage Vin to the detection circuit 440a), causing transistor M2 to conduct and reducing the voltage at the second node N2 to the voltage of the ground terminal (i.e., the detection circuit 440a outputs an enabling signal V1 to the control circuit 440b when the input voltage Vin reaches a predetermined level), thus causing transistor M3 not to conduct and the voltage at the third node N3 to rise to exceed the voltage required for transistor M1 to conduct (i.e., the control circuit 440b outputs a control signal Vctrl to transistor M1), further causing transistor M1 not to conduct, and making the linear regulator 450 receive only the input voltage Vin output by diode D9.

[0055] On the other hand, when the detection circuit 440a does not receive the input voltage Vin, or the input voltage Vin has not been established or is not ready (i.e., the voltage conversion circuit 460 does not output the input voltage Vin or interrupts the output of the input voltage Vin, or the input voltage Vin has not reached 5V), transistor M2 will not conduct. At this time, the values of resistor R3 and resistor R4 are appropriately adjusted to establish a sufficient voltage division at the second node N2 to make transistor M3 conduct. Similarly, the values of resistor R5 and resistor R6 are appropriately adjusted to form a sufficient voltage division at the third node N3 to make transistor M1 conduct. At this time, the voltage received by the linear regulator 450 becomes the input voltage Input1 or the input voltage Input2 output by diode D7 or diode D8.

[0056] It should be noted that although as Figure 4As shown, the power conversion circuit 400 has diodes D7 and D8. However, similar to the power conversion circuit 300, the power conversion circuit 400 may also have only one of the diodes D7 and D8, or have two or more diodes as the input circuit. That is, having only one of the input voltages Input1 and Input2, or having more than two input voltages, can also make the power conversion circuit 400 operate normally. Additionally, although in Figure 4 the voltage conversion circuit 460 is shown as being separate from the switch control circuit 440, the voltage conversion circuit 460 may also be located within the switch control circuit 440. Further, for example, the linear converter 450 may be an LDO, and the voltage conversion circuit 460 may be a pulse width modulation converter.

[0057] The present disclosure provides a novel power conversion circuit that can reduce the difference between the input voltage and the output voltage of a linear regulator by using MOS transistors as switches, thereby achieving the purpose of reducing the energy consumption during the voltage conversion process without relying too much on software settings. Additionally, when the above input voltage is not yet available or interrupted, the power conversion circuit provided by the present disclosure can also reconnect the above input voltage of the above linear converter to the system voltage to prevent the above linear converter from being unable to perform voltage conversion normally due to the absence of an input voltage. Moreover, since the embodiments of the present disclosure may have one or more input circuits (which may also be diodes in some embodiments) and one or more input voltages, it is also very suitable for use in systems or system peripheral product devices with multiple inputs.

[0058] Although the disclosed embodiments have been described and illustrated separately with one or more relevant implementation manners, after reading and understanding this specification and the drawings, other technicians in the art may make equivalent changes and modifications. Additionally, although a particular aspect of the present invention may be disclosed only for one of some embodiments, this aspect may still be combined with one or more other aspects of other embodiments, which may be desirable and advantageous for any given or specific application.

[0059] Although various embodiments of the present disclosure have been described above, it should still be understood that they are shown only by way of example and are not limited to the above examples. Many changes can be made to the disclosed embodiments based on the content of the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the breadth and scope of the present disclosure should not be limited by any of the above embodiments. Instead, the scope of the present disclosure should be defined according to the following appended claims of the invention and their equivalents.

Claims

1. A power conversion circuit, comprising: a first input circuit configured to receive a first input voltage through a first input terminal; a second input circuit configured to receive a second input voltage through a second input terminal, wherein the first input voltage is greater than the second input voltage; a linear regulator configured to receive the first input voltage or the second input voltage to output an output voltage; a switch having a first end and a second end, wherein the first end is coupled to the first input circuit, and the second end is coupled to the second input circuit and the linear regulator; and A switch control circuit is configured to output a control signal to open the switch when receiving the second input voltage and the second input voltage reaches a predetermined level, so as to disconnect the first input voltage from the linear regulator, so that the linear regulator outputs the output voltage according to the second input voltage.

2. The power conversion circuit as claimed in claim 1, further comprising: A voltage conversion circuit is configured to convert the first input voltage into the second input voltage and output the second input voltage to the switch control circuit.

3. The power conversion circuit as claimed in claim 2, wherein the switch control circuit further comprises: a detection circuit configured to output an enable signal when determining that the second input voltage reaches the predetermined level; as well as A control circuit is configured to receive the enable signal and output the control signal.

4. The power conversion circuit as claimed in claim 3, wherein the detection circuit comprises: A first transistor having a first source terminal, a first gate terminal and a first drain terminal; a first resistor coupled between the voltage conversion circuit and a first node; a second resistor coupled between the first node and a ground terminal; as well as a capacitor coupled between the first node and the ground terminal, The first gate terminal is coupled to the first node, the first source terminal is coupled to a second node and is used to output the enable signal, and the first drain terminal is coupled to the ground terminal.

5. The power conversion circuit as claimed in claim 4, wherein the control circuit comprises: a second transistor having a second gate terminal, a second source terminal and a second drain terminal; a third resistor coupled between the first end of the switch and the second node; a fourth resistor coupled between the second node and the ground terminal; a fifth resistor coupled between the first end of the switch and a third node; and a sixth resistor coupled between the third node and the second source terminal, The second gate terminal is coupled to the second node and is used to receive the enable signal, and the second drain terminal is coupled to the ground terminal. 6 . The power conversion circuit as claimed in claim 5 , wherein the switch is a PMOS transistor having a gate terminal coupled to the third node for receiving the control signal.

7. The power conversion circuit as claimed in claim 1, wherein: The first input circuit is a first diode, the anode of the first diode serves as the first input terminal, and the cathode of the first diode is coupled to the first terminal of the switch; and The second input circuit is a second diode, the anode of the second diode serves as the second input terminal, and the cathode of the second diode is coupled to the first terminal of the switch.

8. The power conversion circuit as claimed in claim 1, wherein the linear regulator is a low dropout linear regulator.

9. The power conversion circuit as claimed in claim 1, further comprising: A third input circuit is configured to receive a third input voltage through a third input terminal, wherein the first input voltage is greater than the third input voltage, and the third input voltage is greater than the second input voltage.

10. The power conversion circuit as described in claim 1, wherein when the second input voltage is interrupted or has not reached a predetermined level, the switch control circuit short-circuits the switch to restore the connection between the first input circuit and the linear converter, so that the linear converter outputs the output voltage according to the first input voltage.

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