Power supply circuit, switching power supply chip and electronic device

Abstract

The application belongs to the field of electronic circuits and provides a power supply circuit, a switching power supply chip and an electronic device. The power supply circuit comprises a first power supply module, a second power supply module, a power supply selection module and a charge pump module. The first power supply module is connected with the charge pump module and the power supply selection module respectively, and the second power supply module is connected with the power supply selection module. When the input voltage is a low voltage, the first power supply voltage is output through the cooperative work of the charge pump module and the first power supply module to supply power for the controller, so as to ensure the reliable start of the boost circuit and the smooth transition through the low-voltage start stage. After the normal start of the boost circuit, the power supply switching is realized through the power supply selection module, so as to ensure that the controller provides sufficient gate drive voltage for the power switch tube and makes the switch tube in a fully on state. The switching can effectively reduce the on loss of the circuit and the heating of the device, reduce the burden of the input voltage, support the boost circuit to output greater current at the same time, and finally improve the efficiency and load capacity of the boost circuit.

Description

Technical Field

[0001] This application belongs to the field of electronic circuit technology, and in particular relates to a power supply circuit, a switching power supply chip, and an electronic device. Background Technology

[0002] In a boost converter circuit, the boost controller is powered directly or indirectly by the input voltage. When the input voltage is low, a series of chain reactions occur: the boost controller becomes unstable due to insufficient power supply, failing to provide enough gate drive voltage to the power switch, resulting in the power switch not being able to fully conduct, which in turn increases conduction losses and device heat generation, creating a vicious cycle. Therefore, a low input voltage leads to problems such as difficulty in startup, decreased efficiency, and limited load-carrying capacity in boost converter circuits. Summary of the Invention

[0003] This application provides a power supply circuit, a switching power supply chip, and an electronic device that can solve the problems of difficult startup, reduced efficiency, and limited load capacity caused by low input voltage in Boost converter circuits.

[0004] In a first aspect, embodiments of this application provide a power supply circuit, including a first power supply module, a second power supply module, a power supply selection module, and a charge pump module. The first power supply module is connected to the charge pump module and the power supply selection module, and the second power supply module is connected to the power supply selection module. Both the first power supply module and the second power supply module are used to connect to the Boost controller in the Boost boost circuit. The charge pump module, the first power supply module, and the power supply selection module are all used to receive the input voltage of the Boost boost circuit, and the second power supply module is used to receive the output voltage of the Boost boost circuit.

[0005] When the input voltage is less than or equal to a first threshold voltage, the charge pump module outputs a first voltage based on the input voltage; the first power supply module outputs a first supply voltage based on the first voltage and the input voltage, and uses the first supply voltage as the target supply voltage to power the Boost controller, thereby activating the Boost boost circuit; after the Boost boost circuit is activated, the second power supply module outputs a second supply voltage and a second voltage based on the output voltage; when the output voltage rises to a second threshold voltage, the power supply selection module outputs a third voltage to the first power supply module based on the input voltage and the second voltage, thereby turning off the first power supply module and using the second supply voltage as the target supply voltage.

[0006] In one possible implementation of the first aspect, the power supply selection module is further configured to receive a first signal, and when the input voltage is greater than a third threshold voltage, pull the second voltage down to ground according to the first signal to turn off the second power supply module, thereby making the first power supply voltage the target power supply voltage.

[0007] In one possible implementation of the first aspect, the charge pump module includes a first resistor, a first Zener diode, a first transistor, and a 2x charge pump unit. The first terminal of the first resistor and the drain of the first transistor are both used to receive the input voltage. The second terminal of the first resistor is connected to the cathode of the first Zener diode and the gate of the first transistor, respectively. The anode of the first Zener diode is grounded. The drain of the first transistor is connected to the input terminal of the 2x charge pump unit, and the output terminal of the 2x charge pump unit is connected to the first power supply module.

[0008] In one possible implementation of the first aspect, the first power supply module includes a second transistor, a third transistor, and a second Zener diode. The drain of the second transistor is used to receive an input voltage. The gate of the second transistor is connected to the gate of the third transistor, the cathode of the second Zener diode, the first power supply module, and the power supply selection module, respectively. The anode of the second Zener diode is grounded. The source of the second transistor is connected to the source of the third transistor. The drain of the third transistor is used to output a first power supply voltage.

[0009] In one possible implementation of the first aspect, the first transistor is a high-voltage depletion-mode NMOS transistor; the second transistor is a high-voltage NMOS transistor.

[0010] In one possible implementation of the first aspect, the second power supply module includes a second resistor, a third Zener diode, a fourth transistor, and a fifth transistor. The first terminal of the second resistor and the drain of the fourth transistor are both used to receive the output voltage. The second terminal of the second resistor is connected to the cathode of the third Zener diode, the gate of the fourth transistor, the gate of the fifth transistor, and the power supply selection module, respectively. The anode of the third Zener diode is grounded. The source of the fourth transistor is connected to the source of the fifth transistor. The drain of the fifth transistor is used to output a second power supply voltage.

[0011] In one possible implementation of the first aspect, the power supply selection module includes a sixth transistor, a seventh transistor, and an eighth transistor. The drain of the sixth transistor is used to receive an input voltage. The source of the sixth transistor is connected to the source of the seventh transistor. The drain of the seventh transistor is connected to the first power supply module. The gate of the sixth transistor is connected to the gate of the seventh transistor, the drain of the eighth transistor, and the second power supply module. The source of the eighth transistor is grounded.

[0012] In one possible implementation of the first aspect, the fourth transistor and the sixth transistor are high-voltage NMOS transistors.

[0013] Secondly, embodiments of this application provide a switching power supply chip, including the power supply circuit described in any one of the first aspects.

[0014] Thirdly, embodiments of this application provide an electronic device including the switching power supply chip described in any one of the second aspects.

[0015] The beneficial effects of the embodiments in this application compared with the prior art are:

[0016] This application provides a power supply circuit, including a first power supply module, a second power supply module, a power supply selection module, and a charge pump module. The first power supply module is connected to both the charge pump module and the power supply selection module. The second power supply module is connected to the power supply selection module. Both the first and second power supply modules are used to connect to the Boost controller in the Boost boost circuit. The charge pump module, the first power supply module, and the power supply selection module are all used to receive the input voltage of the Boost boost circuit. The second power supply module is used to receive the output voltage of the Boost boost circuit.

[0017] When the input voltage is less than or equal to a first threshold voltage, the input voltage is considered low, and the charge pump module outputs a first voltage based on the input voltage. The first power supply module outputs a first supply voltage based on the first voltage and the input voltage, and uses this first supply voltage as the target supply voltage to power the Boost controller, thereby activating the Boost boost circuit.

[0018] When the Boost converter is activated, the second power supply module outputs a second supply voltage and a second voltage based on the output voltage. When the output voltage rises to a second threshold voltage, indicating that the first supply voltage and the second supply voltage are equal, a power supply switch is triggered. The power supply selection module outputs a third voltage to the first power supply module based on the input voltage and the second voltage, causing the first power supply module to turn off, thereby making the second supply voltage the target supply voltage.

[0019] As can be seen from the above, when the input voltage is low, this application outputs a first supply voltage through the coordinated operation of the charge pump module and the first power supply module to power the Boost controller, thereby ensuring the reliable startup of the Boost boost circuit and successfully passing through the low-voltage startup stage. After the Boost boost circuit starts normally and the output voltage rises to the second threshold voltage, the power supply selection module realizes the power supply switching: the target supply voltage of the Boost controller is switched from the first supply voltage to the second supply voltage, thereby ensuring that the Boost controller provides sufficient gate drive voltage for the power switch, so that the power switch is in a fully conducting state. This switching can effectively reduce the conduction loss and device heat generation of the circuit, reduce the burden on the input voltage, and support the Boost boost circuit to output a larger current, ultimately improving the efficiency and load capacity of the Boost boost circuit.

[0020] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a power supply circuit provided in an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of a power supply circuit provided in another embodiment of this application;

[0024] Figure 3 This is a circuit connection diagram of a power supply circuit provided in an embodiment of this application;

[0025] Figure 4 This is a circuit connection diagram of a power supply circuit provided in another embodiment of this application;

[0026] Figure 5 This is a schematic diagram of the application of this application to a Boost DC-DC switching power supply chip.

[0027] In the diagram: 10, power supply circuit; 101, first power supply module; 102, second power supply module; 103, power supply selection module; 104, charge pump module; 1041, 2x charge pump unit; 20, Boost boost circuit; 201, Boost controller. Detailed Implementation

[0028] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0029] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0030] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0031] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0032] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0034] In boost converters, low input voltages present three core challenges: startup difficulties, reduced efficiency, and limited load capacity. These challenges are not caused by a single factor, but rather by a series of interconnected physical limitations and loss mechanisms. These interrelated challenges collectively constitute the design difficulties for boost converters with a wide input voltage range (especially including low voltages).

[0035] First, starting is difficult: starting is the first step in the operation of a circuit, and it is particularly vulnerable under low-voltage conditions.

[0036] 1. Boost controller's own "undervoltage lockout": The Boost controller has a minimum operating voltage threshold. If the input voltage is lower than this threshold, the Boost controller cannot start and the circuit is in a "silent" state.

[0037] 2. Insufficient Gate Drive: Even if the Boost controller successfully starts, if it is directly powered by the input voltage, low-voltage conditions may cause the Boost controller to be unable to provide sufficient gate drive voltage to the power switch. The power switch does not turn on completely (the on-resistance Rds_on increases), and the circuit immediately enters a high-loss state, which may lead to startup failure due to device overheating or current limiting.

[0038] 3. Inrush current impact: At startup, the circuit needs to charge the output capacitor. Under low input voltage and high duty cycle conditions, the inductor current rises at an extremely fast rate, which can easily trigger the overcurrent protection function of the Boost controller and cause repeated restarts, resulting in a "hiccup" phenomenon.

[0039] Secondly, efficiency degradation: an energy "gap" during stable operation. Once the circuit starts up, efficiency becomes the core pain point, mainly driven by two types of losses:

[0040] 1. Conduction loss (dominant factor): According to the formula P = I² R, where P represents power, I represents current, and R represents resistance. To provide the same power, the lower the input voltage, the larger the input current. This loss is proportional to the square of the current, causing a sharp increase in losses in the DC resistance DCR of the inductor, the on-resistance Rds_on of the power switch, and the resistance Rtrace of the circuit trace.

[0041] 2. Switching losses and diode losses:

[0042] Each switching action of a power device generates switching losses. Under low input voltage and high current conditions, the switching losses caused by the overlap of voltage and current during switching, as well as the drive losses generated by charging and discharging the gate capacitance, will increase significantly.

[0043] When the reverse recovery charge of the output rectifier diode is depleted under high voltage differential conditions, reverse recovery losses are generated. Under low input voltage conditions, the impact of such losses is more significant.

[0044] Finally, load-carrying capacity is limited: the load-carrying capacity is essentially constrained by the upper limit of the current stress on each component in the circuit.

[0045] Inductor and power switch current stress: Under low input voltage conditions, the peak inductor current will be very high in order to maintain the rated output power. This peak current flows directly through the power switch and the inductor. Once the peak current approaches or exceeds the rated current of the power switch or the saturation current of the inductor, the circuit will trigger current limiting protection. Otherwise, there will be a risk of device damage, thus limiting the maximum output current of the circuit.

[0046] Boost controller self-powered and driven: Many Boost controllers are powered directly or indirectly by the input voltage. Low input voltage conditions may cause the Boost controller to operate unstablely, failing to provide a sufficiently high gate drive voltage to the internal or external power switches. This results in the power switches not being able to fully turn on (increasing the on-resistance Rds_on), further increasing conduction losses and device heat generation, creating a vicious cycle.

[0047] In summary, the limited efficiency and load-carrying capacity of Boost converters under low input voltage conditions are an inevitable result of the combined effects of fundamental physical laws (power conservation) and the non-ideal characteristics of circuit components.

[0048] When designing Boost converters for a wide input voltage range (especially including low voltage), it is essential to evaluate and optimize the solutions to the three major problems mentioned above. Breaking the vicious cycle among these three problems is the core solution approach.

[0049] 1. Select power switches with lower on-resistance Rds_on and inductors with lower DC resistance DCR to reduce circuit conduction losses.

[0050] 2. Carefully calculate the peak inductor current to ensure that there is sufficient margin for the current stress of the power switch and the inductor.

[0051] 3. Improve the startup process.

[0052] 4. Improve efficiency and load-bearing capacity.

[0053] This application primarily addresses the problems of difficult startup, decreased efficiency, and limited load capacity in Boost converters with ultra-wide input voltage ranges (especially including low voltages). To address these issues, this application provides a power supply circuit comprising a first power supply module, a second power supply module, a power supply selection module, and a charge pump module. The first power supply module is connected to both the charge pump module and the power supply selection module. The second power supply module is connected to the power supply selection module. Both the first and second power supply modules are connected to the Boost controller in the Boost converter circuit. The charge pump module, the first power supply module, and the power supply selection module all receive the input voltage of the Boost converter circuit, while the second power supply module receives the output voltage of the Boost converter circuit.

[0054] When the input voltage is low, this application uses the charge pump module and the first power supply module to work together to output a first power supply voltage to power the Boost controller, ensuring reliable startup of the Boost boost circuit and smooth passage through the low-voltage startup stage. After the Boost boost circuit starts normally and the output voltage rises to the second threshold voltage, the power supply selection module switches the power supply: the target power supply voltage of the Boost controller is switched from the first power supply voltage to the second power supply voltage, thereby ensuring that the Boost controller provides sufficient gate drive voltage for the power switch, so that the power switch is in a fully conducting state. This switching can effectively reduce the conduction loss and device heat generation of the circuit, reduce the burden on the input voltage, and support the Boost boost circuit to output a larger current, ultimately improving the efficiency and load capacity of the Boost boost circuit.

[0055] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0056] Figure 1 A schematic diagram of a power supply circuit provided in an embodiment of this application is shown. The power supply circuit 10 provided in this embodiment includes a first power supply module 101, a second power supply module 102, a power supply selection module 103, and a charge pump module 104. The first power supply module 101 is connected to both the charge pump module 104 and the power supply selection module 103. The second power supply module 102 is connected to the power supply selection module 103. Both the first power supply module 101 and the second power supply module 102 are used to connect to the Boost controller 201 in the Boost boost circuit 20. The charge pump module 104, the first power supply module 101, and the power supply selection module 103 are all used to receive the input voltage Vin of the Boost boost circuit 20. The second power supply module 102 is used to receive the output voltage Vout of the Boost boost circuit 20.

[0057] Specifically, when the input voltage Vin is less than or equal to the first threshold voltage, indicating a low voltage, the charge pump module 104 outputs a first voltage V1 based on the input voltage Vin. The first power supply module 101 outputs a first supply voltage VC1 based on the first voltage V1 and the input voltage Vin, and uses the first supply voltage VC1 as the target supply voltage VCC to power the Boost controller 201, thereby activating the Boost boost circuit 20. In this embodiment, the first threshold voltage is set to 4.5V. It should be noted that the minimum input voltage Vin can be 2V.

[0058] When the Boost converter 20 is activated, the second power supply module 102 outputs a second supply voltage VC2 and a second voltage V2 based on the output voltage Vout. When the output voltage Vout rises to the second threshold voltage, it indicates that the first supply voltage VC1 and the second supply voltage VC2 are equal. At this time, a power supply switch is triggered. The power supply selection module 103 outputs a third voltage V3 to the first power supply module 101 based on the input voltage Vin and the second voltage V2, so that the first power supply module 101 is turned off, and the second supply voltage VC2 becomes the target supply voltage VCC. It should be noted that the power supply selection module 103 can only complete the power supply switch when the input voltage is less than or equal to the first threshold voltage, and the output third voltage V3 is the input voltage Vin.

[0059] As can be seen from the above, when the input voltage Vin is low, this application outputs a first supply voltage VC1 through the coordinated operation of the charge pump module 104 and the first power supply module 101 to power the Boost controller 201, so as to ensure that the Boost boost circuit 20 can start reliably and smoothly pass through the low-voltage start-up stage. After the Boost boost circuit 20 starts normally and the output voltage Vout rises to the second threshold voltage, the power supply selection module 103 realizes the power supply switching: the target supply voltage VCC of the Boost controller 201 is switched from the first supply voltage VC1 to the second supply voltage VC2, thereby ensuring that the Boost controller 201 provides sufficient gate drive voltage for the power switch, so that the power switch is in a fully conducting state. This switching can effectively reduce the conduction loss and device heat generation of the circuit, reduce the burden on the input voltage Vin, and support the Boost boost circuit 20 to output a larger current, ultimately improving the efficiency and load capacity of the Boost boost circuit 20.

[0060] In one embodiment of this application, in certain application scenarios, to improve efficiency, it is obviously undesirable to boost a sufficiently high input voltage Vin (i.e., one that can ensure the Boost controller 201 provides sufficient gate drive voltage for the power switch) to a certain output voltage Vout, and then supply power to the Boost controller 201 through the second power supply module 102 outputting the second supply voltage VC2, thus generating additional losses. To avoid the above problems, this application further limits the power supply selection module 103, such as... Figure 2 As shown, the power supply selection module 103 is also used to receive a first signal S1. When the input voltage Vin is greater than the third threshold voltage, the second voltage V2 is pulled down to ground according to the first signal S1, so that the second power supply module 102 is turned off, thereby making the first power supply voltage VC1 the target power supply voltage VCC. The first signal S1 can be generated by comparing the input voltage Vin with the first reference voltage after voltage division, or other generation methods can be used. This application does not limit the generation method of the first signal S1.

[0061] With the above settings, when the input voltage Vin is sufficiently high, the second power supply module 102 is shut off via the power supply selection module 103, forcing the use of the first power supply voltage VC1 output by the first power supply module 101 as the target power supply voltage VCC. It should be noted that the third threshold voltage can be selected as 4.5V, 5V, or other suitable voltage values. That is, this application can arbitrarily define, according to actual needs, that when the input voltage Vin exceeds a certain set voltage, the first power supply voltage VC1 output by the first power supply module 101 will be forcibly selected as the target power supply voltage VCC.

[0062] In one embodiment of this application, such as Figure 3 As shown, the charge pump module 104 includes a first resistor R1, a first Zener diode ZD1, a first transistor M1, and a 2x charge pump unit 1041. The first terminal of the first resistor R1 and the drain of the first transistor M1 are both used to receive the input voltage Vin. The second terminal of the first resistor R1 is connected to the cathode of the first Zener diode ZD1 and the gate of the first transistor M1, respectively. The anode of the first Zener diode ZD1 is grounded. The drain of the first transistor M1 is connected to the input terminal of the 2x charge pump unit 1041, and the output terminal of the 2x charge pump unit 1041 is connected to the first power supply module 101. In this embodiment, the first transistor M1 is a high-voltage depletion-type NMOS transistor.

[0063] Specifically, the input voltage Vin is used to obtain the first clamping voltage Vin_zd through the first resistor R1 and the first Zener diode ZD1. The clamping voltage is up to about 5V and is used to generate the fourth voltage V4 through the first transistor M1. The fourth voltage V4 is used to obtain the first voltage V1 through the double charge pump unit 1041. The first voltage V1 is about twice the fourth voltage V4.

[0064] In one embodiment of this application, such as Figure 3 As shown, the first power supply module 101 includes a second transistor M2, a third transistor M3, and a second Zener diode ZD2. The drain of the second transistor M2 receives the input voltage Vin. The gate of the second transistor M2 is connected to the gate of the third transistor M3, the cathode of the second Zener diode ZD2, the first power supply module 101, and the power selection module 103. The anode of the second Zener diode ZD2 is grounded, and the source of the second transistor M2 is connected to the source of the third transistor M3. The drain of the third transistor M3 outputs the first supply voltage VC1. In this embodiment, the second transistor M2 is a high-voltage NMOS transistor, and the third transistor M3 is a standard NMOS transistor. The second transistor M2 and the third transistor M3 are connected back-to-back, which effectively prevents current backflow in the circuit.

[0065] Specifically, the first voltage V1 is used to obtain a second clamping voltage V1_zd through the second Zener diode ZD2. This clamping voltage has a maximum of approximately 5V. The second clamping voltage V1_zd drives the second transistor M2 and the third transistor M3 to generate the first supply voltage VC1. When the input voltage Vin is less than or equal to the first threshold voltage, the first supply voltage VC1 is the input voltage Vin.

[0066] In one embodiment of this application, such as Figure 3 As shown, the second power supply module 102 includes a second resistor R2, a third Zener diode ZD3, a fourth transistor M4, and a fifth transistor M5. The first terminal of the second resistor R2 and the drain of the fourth transistor M4 are both used to receive the output voltage Vout. The second terminal of the second resistor R2 is connected to the cathode of the third Zener diode ZD3, the gate of the fourth transistor M4, the gate of the fifth transistor M5, and the power supply selection module 103, respectively. The anode of the third Zener diode ZD3 is grounded, and the source of the fourth transistor M4 is connected to the source of the fifth transistor M5. The drain of the fifth transistor M5 is used to output the second power supply voltage VC2. In this embodiment, the fourth transistor M4 is a high-voltage NMOS transistor, and the fifth transistor M5 is a standard NMOS transistor. The fourth transistor M4 and the fifth transistor M5 are connected back-to-back, which effectively prevents current backflow in the circuit.

[0067] Specifically, when the Boost converter 20 is activated, the output voltage Vout is converted into a second voltage V2 through the second resistor R2 and the third Zener diode ZD3. This second voltage V2 drives the fourth transistor M4 and the fifth transistor M5 to generate a second supply voltage VC2. Here, VC2 = V2 - Vthn, where Vthn is the threshold voltage of the NMOS transistor. As the output voltage Vout increases, the second voltage V2 also increases. Due to the clamping effect of the third Zener diode ZD3, the second voltage V2 reaches a maximum of approximately 5V.

[0068] In one embodiment of this application, such as Figure 3 As shown, the power supply selection module 103 includes a sixth transistor M6, a seventh transistor M7, and an eighth transistor M8. The drain of the sixth transistor M6 receives the input voltage Vin. The source of the sixth transistor M6 is connected to the source of the seventh transistor M7. The drain of the seventh transistor M7 is connected to the first power supply module 101. The gate of the sixth transistor M6 is connected to the gate of the seventh transistor M7, the drain of the eighth transistor M8, and the second power supply module 102. The source of the eighth transistor M8 is grounded. In this embodiment, the sixth transistor M6 is a high-voltage NMOS transistor, while the seventh transistor M7 and the eighth transistor M8 are ordinary NMOS transistors. The sixth transistor M6 and the seventh transistor M7 are connected back-to-back, which effectively prevents current backflow in the circuit.

[0069] Specifically, after the Boost converter 20 is started, the output voltage Vout is converted into a second voltage V2 through the second resistor R2 and the third Zener diode ZD3. The second voltage V2 drives the fourth transistor M4 and the fifth transistor M5 to generate a second supply voltage VC2. When the output voltage Vout rises to the second threshold voltage, it indicates that the second supply voltage VC2 is equal to the first supply voltage VC1, and power supply switching is performed at this time. It should be noted that the power supply selection module 103 only performs power supply switching when the input voltage Vin is less than or equal to the first threshold voltage. When the input voltage Vin is less than or equal to the first threshold voltage, the first supply voltage VC1 is equal to the input voltage Vin. Therefore, it can be concluded that the second supply voltage VC2 is equal to the input voltage Vin. According to VC2 = V2 - Vthn, the second voltage V2 is Vthn higher than the input voltage Vin. Therefore, the sixth transistor M6 and the seventh transistor M7 are turned on, outputting a third voltage V3 to the first power supply module 101, thereby pulling the second clamping voltage V1_zd to the third voltage V3. Since the third voltage V3 is equal to the input voltage Vin, the second transistor M2 and the third transistor M3 are turned off, that is, the first power supply module 101 is turned off, and the power supply switch is finally completed, with the second power supply voltage VC2 supplying power to the Boost controller 201.

[0070] When the input voltage Vin is greater than the third threshold voltage, the first signal S1 controls the eighth transistor M8 to turn on, thereby pulling the second voltage V2 down to ground. This turns off the fourth transistor M4 and the fifth transistor M5, i.e., the second power supply module 102 is turned off, thus making the first power supply voltage VC1 the target power supply voltage VCC. Therefore, when the input voltage Vin is sufficiently high, the power supply selection module 103 turns off the second power supply module 102, forcing the use of the first power supply voltage VC1 output by the first power supply module 101 as the target power supply voltage VCC.

[0071] In one embodiment of this application, such as Figure 4 As shown, the power supply selection module 103 also includes a ninth transistor M9. The drain of the ninth transistor M9 is connected to the drain of the seventh transistor M7. The source of the ninth transistor M9 is grounded. The gate of the ninth transistor M9 is used to receive the second signal S2.

[0072] Specifically, in some applications, after the output voltage Vout reaches a certain set voltage, the second power supply voltage VC2 output by the second power supply module 102 can be forcibly selected as the target power supply voltage VCC. The specific implementation is as follows: when the output voltage Vout reaches a certain set voltage, the second signal S2 controls the ninth transistor M9 to turn on, thereby pulling the second clamping voltage V1_zd down to ground; thus, the second transistor M2 and the third transistor M3 turn off, that is, the first power supply module 101 turns off. It should be noted that the second signal S2 can be generated by dividing the output voltage Vout and comparing it with the second reference voltage, or other generation methods can be used. This application does not limit the generation method of the second signal S2.

[0073] The following is combined with Figure 4 and Figure 5 This embodiment explains the working principle.

[0074] Figure 4 The power supply circuit 10 shown is located in Figure 5 The Boost DC-DC switching power supply chip U1 shown here has input voltage pin VIN and output voltage pin VOUT, which are relevant to this embodiment. It should be noted that the output voltage pin VOUT of the Boost DC-DC switching power supply chip U1 can directly sample the output voltage Vout internally. In contrast, most general-purpose DC-DC switching power supply chips use an external output voltage sampling architecture, only providing a voltage sampling feedback pin FB, and lacking an output voltage pin VOUT for direct sampling of the output voltage Vout. Therefore, such general-purpose chips are not suitable for this embodiment.

[0075] When the input voltage Vin is low, assuming it is 2V, in the charge pump module 104, the input voltage Vin passes through the first resistor R1 and the first Zener diode ZD1 to obtain the first clamping voltage Vin_zd, which is 2V. Since the first transistor M1 is a high-voltage depletion-type NMOS transistor with a threshold voltage less than 0, it is turned on, resulting in a fourth voltage V4, which is the input voltage Vin. After passing through the double charge pump unit 1041, the fourth voltage V4 becomes the first voltage V1. Theoretically, the first voltage V1 is twice the fourth voltage V4, and in practice, it can reach about 1.7 times. Therefore, the first voltage V1 is approximately equal to twice the input voltage Vin, and its value is approximately 4V.

[0076] In the first power supply module 101, the first voltage V1 is converted into a second clamping voltage V1_zd through the second Zener diode ZD2. The second clamping voltage V1_zd is approximately 4V. The second clamping voltage V1_zd drives the second transistor M2 and the third transistor M3 to conduct, generating the first supply voltage VC1. Figure 4 It can be seen that the first supply voltage VC1 is equal to the input voltage Vin, and its value is 2V. Combined with... Figure 4 It can be seen that when the input voltage Vin is less than 4.5, the first supply voltage VC1 is the input voltage Vin.

[0077] In the second power supply module 102, after the Boost circuit 20 is started, the output voltage Vout is converted into a second voltage V2 through the second resistor R2 and the third Zener diode ZD3. The second voltage V2 drives the fourth transistor M4 and the fifth transistor M5 to generate a second supply voltage VC2. Here, VC2 = V2 - Vthn. When the output voltage Vout rises to the second threshold voltage, it indicates that the first supply voltage VC1 and the second supply voltage VC2 are equal, i.e., VC2 = V2 - Vthn = VC1 = Vin. At this time, the first supply voltage VC1 and the second supply voltage VC2 are supplied simultaneously. If the range of simultaneous supply is large, a large through current will be generated.

[0078] The sixth transistor M6 and the seventh transistor M7 in the power supply selection module 103 are used to reduce the range of simultaneous power supply, thereby controlling the punch-through current. When the output voltage Vout rises to the second threshold voltage, VC2 = V2 - Vthn = VC1 = Vin. At this time, the power supply is switched, and the sixth transistor M6 and the seventh transistor M7 will conduct, outputting the third voltage V3 to the first power supply module 101. The third voltage V3 is the input voltage Vin, which also pulls the second clamping voltage V1_zd to the input voltage Vin, thereby turning off the second transistor M2 and the third transistor M3, that is, turning off the first power supply module 101. Finally, the power supply switch is completed, and the second supply voltage VC2 supplies power to the Boost controller 201. It is important to note that if the sixth transistor M6, the seventh transistor M7, the fourth transistor M4, and the fifth transistor M5 use the same type of NMOS transistor, the fourth transistor M4 and the fifth transistor M5, as power supply transistors, will definitely have a wider width than the sixth transistor M6 and the seventh transistor M7. The fourth transistor M4 and the fifth transistor M5 are easier to turn on. Therefore, when the second supply voltage VC2 equals the first supply voltage VC1 for power supply switching, the second transistor M2, the third transistor M3, the fourth transistor M4, and the fifth transistor M5 will all be turned on, while the sixth transistor M6 and the seventh transistor M7 will not be turned on yet. There is still a possibility of shoot-through current. Therefore, it is advisable to replace the seventh transistor M7 with a low-voltage NMOS transistor. During power supply switching, the sixth transistor M6 and the seventh transistor M7 will be turned on quickly, thereby quickly pulling the second clamping voltage V1_zd to the input voltage Vin, so as to quickly turn off the second transistor M2 and the third transistor M3 to avoid shoot-through current.

[0079] The ninth transistor M9 and the eighth transistor M8 in the power supply selection module 103 can pull down the second clamping voltage V1_zd and the second voltage V2, thereby forcibly shutting down the first power supply module 101 or the second power supply module 102.

[0080] When the input voltage Vin is high, assuming it is 20V, in the charge pump module 104, the input voltage Vin passes through the first resistor R1 and the first Zener diode ZD1 to obtain a first clamping voltage Vin_zd, which is 5V. The first clamping voltage Vin_zd drives the first transistor M1 to obtain a fourth voltage V4, which is 5.5V. After passing through the double charge pump unit 1041, the fourth voltage V4 is used to obtain the first voltage V1, which is approximately twice the fourth voltage V4, and its value is approximately 11V.

[0081] In the first power supply module 101, the first voltage V1 is converted into a second clamping voltage V1_zd through the second Zener diode ZD2. The second clamping voltage V1_zd is approximately 5V. The second clamping voltage V1_zd drives the second transistor M2 and the third transistor M3 to conduct, generating a first supply voltage VC1, which is approximately 4.5V.

[0082] In the second power supply module 102, after the Boost circuit 20 is activated, the output voltage Vout rises rapidly and generates a second voltage V2 through the second resistor R2 and the third Zener diode ZD3. The second voltage V2 is approximately 5V. This second voltage V2 drives the fourth transistor M4 and the fifth transistor M5 to generate a second supply voltage VC2, which is approximately 4.5V. At this point, it is necessary to determine whether the power supply should be provided by the input voltage Vin or the output voltage Vout under the same conditions. Besides forcing the use of the input voltage Vin by judging its performance, an NMOS transistor with its drain and gate shorted can be connected below the second Zener diode ZD2 to raise the second clamping voltage V1_zd, thus prioritizing the use of the input voltage Vin. Similarly, prioritizing the use of the output voltage Vout can also be achieved.

[0083] In summary, this application is applicable to an ultra-wide input voltage range (2V~40V). When the input voltage Vin is as low as 2V, the charge pump module 104 and the first power supply module 101 work together to output a first power supply voltage VC1 to power the Boost controller 201, ensuring the reliable startup of the Boost boost circuit 20 and successfully navigating the low-voltage startup phase. After the Boost boost circuit 20 starts normally, a timely power supply switch is performed: the target power supply voltage VCC of the Boost controller 201 is switched from the first power supply voltage VC1 to the second power supply voltage VC2 (that is, switched from being powered by the input voltage Vin to being powered by the output voltage Vout), thereby ensuring that the Boost controller 201 provides sufficient gate drive voltage for the power switch, so that the power switch is in a fully conducting state. This switch can effectively reduce the conduction loss and device heat generation of the circuit, reduce the burden on the input voltage Vin, and support the Boost boost circuit 20 to output a larger current, ultimately improving the efficiency and load capacity of the Boost boost circuit 20.

[0084] This application also provides a switching power supply chip, including the power supply circuit described above. Since the switching power supply chip provided in this application adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be elaborated further here.

[0085] This application also provides an electronic device, including the switching power supply chip described above. Since the electronic device provided in this application adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be elaborated upon further here.

[0086] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0087] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A power supply circuit, characterized in that, It includes a first power supply module, a second power supply module, a power supply selection module, and a charge pump module. The first power supply module is connected to both the charge pump module and the power supply selection module. The second power supply module is connected to the power supply selection module. Both the first power supply module and the second power supply module are used to connect to the Boost controller in the Boost boost circuit. The charge pump module, the first power supply module, and the power supply selection module are all used to receive the input voltage of the Boost boost circuit. The second power supply module is used to receive the output voltage of the Boost boost circuit. When the input voltage is less than or equal to the first threshold voltage, the charge pump module is used to output a first voltage according to the input voltage; The first power supply module is used to output a first power supply voltage according to the first voltage and the input voltage, and use the first power supply voltage as the target power supply voltage to power the Boost controller so as to start the Boost boost circuit; When the Boost circuit is started, the second power supply module is used to output a second power supply voltage and a second voltage according to the output voltage; when the output voltage rises to a second threshold voltage, the power supply selection module is used to output a third voltage to the first power supply module according to the input voltage and the second voltage, so as to turn off the first power supply module and make the second power supply voltage the target power supply voltage. The power supply selection module is also used to receive a first signal. When the input voltage is greater than the third threshold voltage, the second voltage is pulled down to ground according to the first signal so as to turn off the second power supply module, thereby making the first power supply voltage the target power supply voltage.

2. The power supply circuit according to claim 1, characterized in that, The charge pump module includes a first resistor, a first Zener diode, a first transistor, and a 2x charge pump unit. The first terminal of the first resistor and the drain of the first transistor are both used to receive the input voltage. The second terminal of the first resistor is connected to the cathode of the first Zener diode and the gate of the first transistor, respectively. The anode of the first Zener diode is grounded. The source of the first transistor is connected to the input terminal of the 2x charge pump unit. The output terminal of the 2x charge pump unit is connected to the first power supply module.

3. The power supply circuit according to claim 2, characterized in that, The first power supply module includes a second transistor, a third transistor, and a second Zener diode. The drain of the second transistor is used to receive the input voltage. The gate of the second transistor is connected to the gate of the third transistor, the cathode of the second Zener diode, the first power supply module, and the power supply selection module. The anode of the second Zener diode is grounded. The source of the second transistor is connected to the source of the third transistor. The drain of the third transistor is used to output the first power supply voltage.

4. The power supply circuit according to claim 3, characterized in that, The first transistor is a high-voltage depletion-mode NMOS transistor; the second transistor is a high-voltage NMOS transistor.

5. The power supply circuit according to claim 1, characterized in that, The second power supply module includes a second resistor, a third Zener diode, a fourth transistor, and a fifth transistor. The first terminal of the second resistor and the drain of the fourth transistor are both used to receive the output voltage. The second terminal of the second resistor is connected to the cathode of the third Zener diode, the gate of the fourth transistor, the gate of the fifth transistor, and the power supply selection module, respectively. The anode of the third Zener diode is grounded. The source of the fourth transistor is connected to the source of the fifth transistor. The drain of the fifth transistor is used to output the second power supply voltage.

6. The power supply circuit according to claim 5, characterized in that, The power supply selection module includes a sixth transistor, a seventh transistor, and an eighth transistor. The drain of the sixth transistor is used to receive the input voltage. The source of the sixth transistor is connected to the source of the seventh transistor. The drain of the seventh transistor is connected to the first power supply module. The gate of the sixth transistor is connected to the gate of the seventh transistor, the drain of the eighth transistor, and the second power supply module. The source of the eighth transistor is grounded.

7. The power supply circuit according to claim 6, characterized in that, The fourth and sixth transistors are high-voltage NMOS transistors.

8. A switching power supply chip, characterized in that, Includes the power supply circuit as described in any one of claims 1-7.

9. An electronic device, characterized in that, Includes the switching power supply chip as described in claim 8.

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