Soft Start Method for Switching Regulator

Abstract

The present invention discloses a soft start method for a switching regulator, comprising the following steps: providing a first gate drive signal to a switching circuit through a control circuit to generate an output voltage and an output current, wherein the first gate drive signal includes a plurality of first switching cycles; detecting the output voltage and the output current through a voltage feedback circuit; determining whether a mode switching condition is satisfied based on the output voltage and the output current obtained by the control circuit; and when the mode switching condition is satisfied, providing a second gate drive signal to the switching circuit through the control circuit to increase the output voltage to a predetermined voltage, wherein the second gate drive signal has a plurality of second switching cycles. The soft start method for a switching regulator according to an embodiment of the present invention can limit the output current to an allowable range when the switching regulator is just turned on. In addition, the output voltage can also rise to a predetermined voltage within a relatively short boost time.

Description

Technical Field

[0001] The present invention relates to a soft start method for a switching regulator, in particular to a two-stage soft start method for a switching regulator. Background Art

[0002] Switching power regulators are widely used to perform DC-to-DC or AC-to-DC voltage conversion, converting an initial input voltage into the voltage required by at least one load device coupled to the switching power regulator. A switching power regulator typically includes a control unit and two or three power transistors electrically connected to the control unit to perform these functions. However, when a switching power regulator is first turned on, an inrush current may be generated, potentially damaging the load device.

[0003] Generally speaking, to suppress inrush current and protect load components from damage when a switching power regulator is first turned on, the switching power regulator can operate in pulse frequency modulation (PFM) mode, causing the output voltage of the switching power regulator to slowly increase to a predetermined voltage. However, if the switching power regulator only operates in PFM mode to suppress inrush current when it is first turned on, the ramp-up time required to increase the output voltage to the predetermined voltage is too long.

[0004] Therefore, a switching power regulator can operate in another mode, namely pulse width modulation (PWM) mode, when it is first turned on to reduce the rise time. However, if the switching power regulator only operates in PWM mode when it is first turned on, it is difficult to control the inrush current within an acceptable range when the switching power regulator is first turned on. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a soft start method for a switching regulator, so as to limit the inrush current to an allowable range when the switching regulator is just turned on, and increase the output voltage to a predetermined voltage within a relatively short boost time.

[0006] To solve the above-mentioned technical problems, one of the technical solutions adopted by the present invention is to provide a soft-start method for a switching regulator, which includes the following steps: providing a first gate drive signal to a switching circuit through a control circuit to generate an output voltage and an output current, wherein the first gate drive signal includes a plurality of first switching cycles; detecting the output voltage through a voltage feedback circuit and detecting the output current through a current feedback circuit; determining whether a mode switching condition is satisfied based on the output voltage and output current obtained by the control circuit; and when the mode switching condition is satisfied, providing a second gate drive signal to the switching circuit through the control circuit to increase the output voltage to a predetermined voltage, wherein the second gate drive signal has a plurality of second switching cycles.

[0007] Furthermore, the soft start method of the switching regulator further includes: when the mode switching condition is not satisfied, the control circuit still provides the first gate driving signal to the switching circuit.

[0008] Furthermore, the first gate driving signal is a pulse-skip modulation signal, and the second gate driving signal is a pulse-width modulation signal.

[0009] Furthermore, the soft start method of the switching regulator includes: providing an input voltage to the switching circuit through a power supply, wherein each first switching cycle of the first gate drive signal includes an on-time, and the input voltage, the output voltage, and the on-time satisfy the following relationship:

[0010] (V in / L)×t on <N;

[0011] Where, L represents a predetermined inductance value, V in represents the input voltage, t on represents the on-time, and N represents an adjustable value ranging from 10μA to 150μA.

[0012] Furthermore, a ratio of a second period of the second switching cycle to a first period of the first switching cycle ranges from 0.01 to 3.

[0013] Furthermore, the output current has a plurality of rise and fall cycles, and the mode switching condition includes that the output voltage is greater than or equal to a threshold voltage, and a duration of each rise and fall cycle is less than a second period of each second switching cycle.

[0014] Furthermore, the switching regulator is a buck converter or a boost converter.

[0015] Furthermore, a soft-start method for a switching regulator includes calculating a parameter value by dividing the output voltage by a predetermined inductance value, wherein the output current has a plurality of ramp-up and ramp-down cycles, and the mode switching condition includes that the parameter value is greater than or equal to a threshold, and a duration of each ramp-up and ramp-down cycle is less than a second period of each second switching cycle.

[0016] Furthermore, a first gate drive signal is provided at a start-up time point, and a second gate drive signal is provided at a switching time point. The output voltage increases slowly over time during the time period from the start-up time point to the switching time point, and increases rapidly over time after the switching time point until the output voltage reaches a predetermined voltage.

[0017] To solve the aforementioned technical problems, another technical solution adopted by the present invention is to provide a soft-start method for a switching regulator, comprising: providing a pulse-skip modulation signal to a switching circuit via a control circuit in a first soft-start phase to generate an output voltage and an output current, wherein the pulse-skip modulation signal includes a plurality of first switching cycles; determining whether a mode switching condition is satisfied based on the output voltage and the output current; and providing a pulse-width modulation (PWM) signal to the switching circuit in a second soft-start phase to increase the output voltage to a predetermined voltage when the mode switching condition is satisfied, wherein the pulse-width modulation signal includes a plurality of second switching cycles, and the first soft-start phase is earlier than the second soft-start phase.

[0018] Furthermore, the output current has a plurality of rise and fall cycles, and the mode switching condition includes that the output voltage is greater than or equal to a threshold voltage, and a duration of each rise and fall cycle is less than a second period of each second switching cycle.

[0019] Furthermore, the output current has a plurality of ramp-up and ramp-down cycles, and the soft-start method of the switching regulator includes: calculating a parameter value by dividing the output voltage by a predetermined inductance value, wherein the output current has a plurality of ramp-up and ramp-down cycles, and the mode switching condition includes that the parameter value is greater than or equal to a threshold value, and a duration of each ramp-up and ramp-down cycle is less than a second period of each second switching cycle.

[0020] Furthermore, in the first slow start phase, the output voltage increases slowly over time, and in the second slow start phase, the output voltage increases rapidly over time until the output voltage reaches a predetermined voltage.

[0021] Furthermore, the soft start method of the switching regulator includes: providing an input voltage to the switching circuit through a power supply, wherein each first switching cycle of the first gate drive signal includes an on-time, and the input voltage, the output voltage, and the on-time satisfy the following relationship:

[0022] (V in / L)×t on <N;

[0023] Where, L represents a predetermined inductance value, V in represents the input voltage, t on represents the on-time, and N represents an adjustable value ranging from 10μA to 150μA.

[0024] Furthermore, a ratio between a first period of each first switching cycle and a second period of each second switching cycle ranges from 0.01 to 3.

[0025] One of the beneficial effects of the present invention is that the soft-start method for a switching regulator provided in an embodiment of the present invention, by "providing a first gate drive signal to a switching circuit in a first soft-start phase to generate an output voltage and an output current, wherein the first gate drive signal includes multiple first switching cycles" and "providing a second gate drive signal to the switching circuit in a second soft-start phase, wherein the second gate drive signal includes multiple second switching cycles," can limit the output current to an acceptable range when the switching regulator is first turned on. Furthermore, the output voltage can be raised to a predetermined voltage within a relatively short ramp-up time.

[0026] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. 4 is a flow chart of a soft-start method for a switching regulator according to an embodiment of the present invention.

[0028] Figure 2 FIG. 1 is a circuit diagram of a DC-to-DC buck converter according to an embodiment of the present invention.

[0029] Figure 3 FIG. 1 is a waveform diagram of a gate driving signal according to an embodiment of the present invention.

[0030] Figure 4 is the output current (I L ) waveform diagram.

[0031] Figure 5is the output voltage (V out ) and time. DETAILED DESCRIPTION

[0032] The following is an explanation of the implementation of the "soft start method for a switching regulator" disclosed in the present invention through specific examples. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. Please note in advance. The following embodiments will further explain the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention.

[0033] Please refer to Figure 1 , Figure 1 This is a flow chart of a soft-start method for a switching regulator according to an embodiment of the present invention. The soft-start method according to the embodiment of the present invention can be performed on a switching regulator, such as a step-up switching regulator or a step-down switching regulator, to convert an input voltage into a pulsed output voltage, which can then be smoothed by capacitors, inductors, or other components.

[0034] In an embodiment of the present invention, a soft-start method is executed before the output voltage of a switching regulator reaches a predetermined voltage value to suppress inrush current. Furthermore, the soft-start period of the switching regulator can be divided into at least two stages, such as a first stage and a second stage. The switching regulator can operate in different modes during the first and second stages, respectively, to shorten the soft-start period while suppressing inrush current that may be generated during the soft-start period. The detailed steps of the soft-start method are described below.

[0035] Please refer to Figure 1 , Figure 1 This is a flow chart of a soft-start method for a switching regulator according to an embodiment of the present invention. The soft-start method can be performed by a switching regulator, such as a buck switching regulator or a boost switching regulator, to convert an input voltage into a pulsed output voltage. The pulsed output voltage can be smoothed by at least one of a capacitor, an inductor, or other components.

[0036] Please refer to Figure 2 , which is a circuit diagram of a DC-to-DC buck converter according to an embodiment of the present invention. Figure 2 The switching regulator 1 shown is a step-down switching regulator, but the present invention is not limited thereto. Figure 2As shown, the switching regulator 1 may include a control circuit 10 , a switching circuit 11 , a voltage feedback circuit 12 , a current feedback circuit 13 , an inductor L1 , and a capacitor C1 .

[0037] The control circuit 10 is electrically coupled to the switch circuit 11 to provide a gate drive signal to the switch circuit 11. In this embodiment, the switch circuit 11 includes two field-effect transistors (FETs) M1 and M2 electrically connected in series, but the present invention is not limited thereto. In another embodiment, the switch circuit 11 may include a transistor and a diode electrically connected to each other.

[0038] In addition, the switch circuit 11 is electrically connected to the inductor L1 and the capacitor C1. The inductor L1 and the capacitor C1 are both designed to stabilize the output voltage. In this embodiment, the inductor L1 has a predetermined inductance value.

[0039] The voltage feedback circuit 12 is used to detect the output voltage and is electrically connected between the control circuit 1 and one end of the inductor L1. The voltage feedback circuit 12 may include at least one comparator that compares the output voltage with a reference voltage to determine whether the output voltage is equal to or greater than the reference voltage. When the voltage feedback circuit 12 determines that the output voltage is equal to or greater than the reference voltage, the voltage feedback circuit 12 transmits a switching signal to the control circuit 10.

[0040] After the control circuit 10 receives the switching signal transmitted by the voltage feedback circuit 12, the control circuit 10 can adjust parameters based on the switching signal, such as the cycle period or duty ratio of the gate drive signal provided to the switch circuit 11. In another embodiment, the voltage feedback circuit 12 can be integrated with the control circuit 10.

[0041] In addition, the current feedback circuit 13 can be electrically connected between one end of the inductor L1 and the control circuit 10 to detect the output current I flowing through the inductor L1. L The current feedback circuit 13 detects the output current I L And according to the output current I L The signal is sent to the control circuit 10. Similarly, the control circuit 10 can detect the output current I L , control or adjust the gate drive signal. In addition, the input voltage V in A power supply ( Figure 2 (not shown) is provided to the switch circuit 11.

[0042] Figure 2The switching regulator 1 shown is only used as an example to explain the soft-start method of the present invention. However, the soft-start method provided by the present invention is not limited to being executed by a buck switching regulator, but can also be executed by other types of regulators, such as a boost switching regulator. Figure 1 The detailed steps of the slow start method will be shown in conjunction with Figure 2 The switching regulator 1 shown is described.

[0043] Furthermore, the switching regulator 1 can implement the soft-start method of the present invention to limit inrush current before the output voltage of the switching regulator 1 reaches a predetermined voltage. Furthermore, in one embodiment, the soft-start method of the switching regulator 1 can be divided into at least two stages, such as a first soft-start stage and a second soft-start stage. The switching regulator 1 can operate in different modes in the first and second soft-start stages, respectively, to shorten the soft-start time; at the same time, the inrush current can be limited during the soft-start time. The detailed steps of the soft-start method are described below.

[0044] Please refer to Figure 1 In step S10, the control circuit provides a first gate drive signal having a plurality of first switching cycles to the switch circuit to generate an output voltage and an output current. In step S20, the output voltage and output current are detected by the voltage feedback circuit and the current feedback circuit, respectively.

[0045] Furthermore, if Figure 2 As shown, the control circuit 10 can provide a first gate drive signal to the switch circuit 11 to control the opening and closing of the two field effect transistors M1 and M2 of the switch circuit 11. The first gate drive signal includes a plurality of first switching cycles. The switch circuit 11 can be based on the first gate drive signal and the input voltage V in And provide output voltage V out And the output current I L .

[0046] In this embodiment, the voltage feedback circuit 12 can detect the output voltage V out , and the current feedback circuit 13 can detect the output current I L The control circuit 10 can obtain the output voltage V based on the signals transmitted by the voltage feedback circuit 12 and the current feedback circuit 13 respectively. out With the output current I L In this way, the control circuit 10 can adjust the output voltage V out .

[0047] Please refer to Figure 3, which is a waveform diagram of a gate driving signal according to an embodiment of the present invention. In this embodiment, at the startup time point t0, that is, when the switching regulator 1 begins to operate, the control circuit 10 provides a first gate driving signal GS1.

[0048] like Figure 3 As shown, the first gate driving signal GS1 has a plurality of first switching cycles, and each first switching cycle has a first period T1. In addition, each first period T1 includes an on time t on With closing time t off That is, the opening time t on With closing time t off The sum of is the first period T1.

[0049] Providing a first gate drive signal GS1 can be used to limit inrush current, and the first gate drive signal GS1 can be a pulse skip modulation (PSM) signal. In one embodiment, the pulses of the PSM signal can be generated by the control circuit 10. Specifically, the control circuit 10 can determine whether to skip pulses of the PSM signal in a certain cycle based on signals transmitted by the voltage feedback circuit 12 and the current feedback circuit 13. However, the pulse frequency and width of the PSM signal are fixed values.

[0050] In addition, in one embodiment, the input voltage V in , predetermined inductance value L and turn-on time t on The following relationship is satisfied:

[0051] (V in / L)×t on <N。

[0052] L represents the predetermined inductance value, V in represents the input voltage, t on represents the on-time of each first switching cycle, N represents an adjustable value, and the range is, for example, from 10μA to 150μA. That is, the on-time of each first switching cycle t on It can be preset according to the above relationship to limit the inrush current.

[0053] Output current I L The on-time t of each first switching cycle can be on It rises linearly and during the off time t of each first switching cycle off Decrease linearly.

[0054] Please refer to Figure 4 , Figure 4is the output current (I L ) is a waveform diagram. It should be noted that the output current I output by the switch circuit 11 L There can be multiple lifting cycles, and each of the lifting cycles has a different duration T D In one embodiment, during the soft start period, that is, from the start time point t0 to the switching time point t1, the duration of the rise and fall cycle T D Will decrease over time.

[0055] like Figure 4 As shown, in each rise and fall cycle, the output current I L It increases with an increasing slope and then decreases with a decreasing slope. Figure 4 As shown, the output current I L In the initial rise and fall cycle, since the output voltage is close to zero, the input voltage V in Divide by the predetermined inductance value L to get the rising slope S a That is, the rising slope S of the initial lifting cycle a 、Input voltage V in And the predetermined inductance value L satisfies the following relationship: S a =V in / L. In addition, the rise time t a The on-time t of each first switching cycle can be on To decide.

[0056] In one embodiment, the first period T1 of each first switching cycle may be substantially equal to the output current I L The duration of the initial lifting cycle is T D .

[0057] Please refer to Figure 1 In step S30, it is determined whether the mode switching condition is satisfied. Specifically, the control circuit 10 can obtain the output voltage V out And the output current I L , to determine whether the mode switching conditions are met.

[0058] When the control circuit 10 determines that the mode switching condition is not satisfied, the soft start method returns to step S10 and is repeated. That is, the control circuit 10 continues to provide the first gate driving signal GS1 before the mode switching condition is satisfied.

[0059] When the control circuit 10 determines that the mode switching condition is met, the soft-start method proceeds to step S40 . In step S40 , the control circuit 10 provides a second gate drive signal having a plurality of second switching cycles to the switching circuit. Accordingly, the control circuit 10 continues to provide the first gate drive signal until the mode switching condition is met.

[0060] Please refer to Figure 3 If the mode switching condition is met at the switching time point t1, the control circuit 10 will start to provide the second gate drive signal GS2 to the switch circuit 11 at the switching time point t1. Accordingly, the first slow start phase starts at the start time point t0 and ends at the switching time point t1, and the second slow start phase starts at the switching time point t1.

[0061] It should be noted that the mode switching condition can be based on at least the output current I L Or the output voltage V out After the mode switching conditions are met, the probability of inrush current generation will be low enough to allow the output voltage V out That is to say, in the second slow start phase, even if the output voltage V out Increases at a faster rate of rise, the output current I L It can also be controlled not to exceed a preset upper limit value I th ,like Figure 4 As shown. To increase the output voltage V out The second gate driving signal GS2 with a rising rate of 100 can be provided to the switching circuit 11. In addition, the details of the mode switching condition will be described below.

[0062] Accordingly, in the soft start method of the embodiment of the present invention, two different gate driving signals (ie, the first and second gate driving signals GS1 and GS2 ) are provided by the control circuit 10 to the switch circuit 11 in the first and second soft start phases, respectively.

[0063] Specifically, by providing the first gate drive signal GS1 to the switch circuit 11 in the first slow start phase until the inrush current no longer occurs, the inrush current can be suppressed or avoided. In addition, by providing the second gate drive signal GS2 to the switch circuit 11 in the second slow start phase, the output voltage V out It can be increased to a predetermined voltage in a relatively short time. Accordingly, by executing the soft start method of the present invention, the output voltage V out The boost time required to reach the predetermined voltage is short.

[0064] The second gate driving signal GS2 includes a plurality of second switching cycles, such as Figure 3Each second switching cycle has a second period T2, and the second period T2 also includes an on time t on With a closing time t off In addition, the ratio of the second period T2 of each second switching cycle to the first period T1 of each first switching cycle ranges from 0.01 to 3, for example.

[0065] In one embodiment, the first gate drive signal GS1 is a pulse skip modulation (PSM) signal, while the second gate drive signal GS2 is a pulse width modulation (PWM) signal. That is, the switching regulator 1 operates in the PSM mode until a mode switching condition is met. In one embodiment, the frequency of the PWM signal may be approximately 10 times the frequency of the PSM signal.

[0066] It should be noted that the mode switching condition may include at least one requirement. In one embodiment of the present invention, the mode switching condition includes two requirements, one of which is that the output voltage V out Greater than or equal to a threshold voltage (V th ), and another requirement is the output current I L The duration of each lifting cycle is T D is smaller than a second period T2 of each second switching cycle.

[0067] That is, when the control circuit 10 determines that the output voltage V out Greater than or equal to the threshold voltage (V th ), and the output current I L The duration of the rise and fall cycle is T D When the time period T2 is less than a second switching cycle, the soft start method proceeds to step S40 .

[0068] On the contrary, when the control circuit 10 determines that the output voltage V out Less than the threshold voltage (V th ), or the output current I L The duration of the rise and fall cycle is T D The control circuit 10 continuously provides the first gate driving signal GS1 to the switch circuit 11 for a second period T2 that is greater than or equal to each second switching cycle.

[0069] It is worth mentioning that the threshold voltage (V th ) can be preset according to the upper limit of the required inrush current. Specifically, if the upper limit of the required inrush current is lower, the threshold voltage will be set lower.

[0070] In another embodiment, the soft start method further includes: out Divide by a predetermined inductance value L to calculate a parameter value. That is, the parameter value, output voltage V out And the predetermined inductance value L satisfies the following relationship: V out / L=M, where V out represents the output voltage detected by the voltage feedback circuit 12, L represents a predetermined inductance value, and M represents a parameter value.

[0071] In this embodiment, the mode switching condition may include that the parameter value (M) is greater than or equal to a threshold value, and a duration T of each rise and fall cycle is D That is, when the control circuit 10 determines that the parameter value (M) is greater than or equal to the threshold value, and the duration of each rise and fall cycle T D When the second period T2 is less than each second switching cycle, the soft start method proceeds to step S40 .

[0072] On the contrary, if the parameter value (M) is less than the threshold, or the duration of the rise and fall cycle T D The control circuit 10 will continue to provide the first gate driving signal GS1 to the switch circuit 11 for a period greater than or equal to the second period T2 of each second switching cycle.

[0073] As described above, after the mode switching condition is satisfied, the probability of generating surge current can be greatly reduced. Accordingly, the second gate drive signal GS2 can be provided to the switch circuit 11 to increase the output voltage V out The rising rate of the output voltage V out The voltage can be increased to a predetermined voltage within a relatively short boost time.

[0074] Please refer to Figure 5 , which is the output voltage (V out ) and time. It should be noted that by providing the first gate drive signal GS1 to the switch circuit 11, the output voltage V out It starts to increase and then reaches a threshold voltage V at the switching time point t1 th The switching time point t1 is the time point when the mode switching condition is satisfied. After the switching time point t1, the second gate drive signal GS2 is provided by the control circuit 10 to the switch circuit 11, so that the output voltage V out As time increases, until the output voltage V out Reaching the predetermined voltage V f .

[0075] like Figure 5 As shown, by using the above-mentioned slow start method, the output voltage Vout Reaching the predetermined voltage V f Before, the output voltage V out It will rise at different slopes in different slow start phases.

[0076] Furthermore, if Figure 3 and Figure 5 As shown, since the first gate drive signal GS1 is provided from the start time point t0 to the switching time point t1, the output voltage V out In the first slow start phase (i.e., from the start time point t0 to the switching time point t1), the output voltage V out As time increases rapidly, until the output voltage V out reaches the predetermined voltage V f That is to say, in the second slow start phase, the output voltage V out will increase at a faster rate of rise. out The rising rate (or slope) in the second slow start phase will be greater than the output voltage V out The rate of rise (or slope) in the first slow start phase.

[0077] However, even if the output voltage V out Reaching the predetermined voltage V f , the control circuit 10 will continue to provide the second gate drive signal GS2 to the switch circuit 11. As described above, the second gate drive signal GS2 can be a pulse width modulation signal. Accordingly, after the mode switching condition is met, the switching regulator 1 will continue to operate in the pulse width modulation mode.

[0078] In summary, one of the beneficial effects of the present invention is that, in the soft start method of the switching regulator, by providing the first gate drive signal GS1 having a plurality of first switching cycles to the switching circuit 11 in the first soft start phase, and providing the second gate drive signal GS2 having a plurality of second switching cycles to the switching circuit in the second soft start phase, when the switching regulator 1 is just started, the output current I L can be limited to an allowable range. In addition, the output voltage V out It can be increased to a predetermined voltage V in a relatively short boost time f .

[0079] Furthermore, in the soft start method of the present invention, the first gate drive signal GS1 provided in the first soft start phase can be used to limit or avoid inrush current, and the second gate drive signal GS2 provided in the second soft start phase can increase the output voltage V out The rise rate.

[0080] In one embodiment, the switching regulator 1 operates in a pulse skipping modulation mode in the first slow start phase and in a pulse width modulation mode in the second slow start phase. Since the probability of generating an inrush current in the second slow start phase is relatively low, by providing a pulse width modulation signal (or a second gate drive signal GS2) to the switching circuit 11 after the mode switching condition is met, the output voltage Vout can rise rapidly in the second slow start phase. Thus, compared to the existing slow start method, by executing the slow start method of the present invention, the output voltage Vout can be reduced. out At the same time, it is also easier to limit the inrush current or avoid the inrush current.

[0081] The contents disclosed above are only preferred feasible embodiments of the present invention and do not limit the scope of protection of the claims of the present invention. Therefore, all equivalent technical changes made using the contents of the description and drawings of the present invention are included in the scope of protection of the claims of the present invention.

Claims

1. A soft start method for a switching regulator, characterized in that: The soft start method of the switching regulator includes: Providing a first gate driving signal to a switching circuit through a control circuit to generate an output voltage and an output current, wherein the first gate driving signal includes a plurality of first switching cycles; detecting the output voltage through a voltage feedback circuit and detecting the output current through a current feedback circuit; determining whether a mode switching condition is satisfied according to the output voltage and the output current obtained by the control circuit; and When the mode switching condition is met, a second gate drive signal is provided to the switch circuit through the control circuit to increase the output voltage to a predetermined voltage, wherein the second gate drive signal has a plurality of second switching cycles. The output current has a plurality of rise and fall cycles, and the mode switching condition includes that the output voltage is greater than or equal to a threshold voltage, and a duration of each of the rise and fall cycles is less than a second period of each of the second switching cycles.

2. The soft start method of the switching regulator according to claim 1, characterized in that: The soft start method of the switching regulator further comprises: When the mode switching condition is not satisfied, the control circuit still provides the first gate driving signal to the switch circuit.

3. The soft start method of the switching regulator according to claim 1, wherein: The first gate driving signal is a pulse-skip modulation signal, and the second gate driving signal is a pulse-width modulation signal.

4. The soft start method of the switching regulator according to claim 1, wherein: The soft start method of the switching regulator includes: An input voltage is provided to the switching circuit via a power supply, wherein each of the first switching cycles of the first gate driving signal includes an on-time, and the input voltage, the output voltage, and the on-time satisfy the following relationship: (V in / L)×t on <N Where, L represents a predetermined inductance value, V in represents the input voltage, t on represents the on-time, and N represents an adjustable value ranging from 10 μA to 150 μA.

5. The soft start method of the switching regulator according to claim 1, wherein: A ratio of the second period of the second switching cycle to a first period of the first switching cycle ranges from 0.01 to 3.

6. The soft start method of the switching regulator according to claim 1, wherein: The switching regulator is a buck regulator or a boost regulator.

7. The soft start method of a switching regulator according to claim 1, wherein: The soft start method of the switching regulator includes: A parameter value is calculated by dividing the output voltage by a predetermined inductance value, wherein the mode switching condition includes that the parameter value is greater than or equal to a threshold value.

8. The soft start method of a switching regulator according to claim 1, wherein: The first gate drive signal is provided at a start-up time point, and the second gate drive signal is provided at a switching time point. The output voltage increases slowly over time during a time period from the start-up time point to the switching time point, and increases rapidly over time after the switching time point until the output voltage reaches the predetermined voltage.

9. A soft start method for a switching regulator, characterized in that: The soft start method of the switching regulator includes: In a first soft start phase, a control circuit provides a pulse skipping modulation signal to a switching circuit to generate an output voltage and an output current, wherein the pulse skipping modulation signal includes a plurality of first switching cycles; determining whether a mode switching condition is satisfied according to the output voltage and the output current; and When the mode switching condition is met, a pulse width modulation signal is provided to the switching circuit in a second soft start phase to increase the output voltage to a predetermined voltage, wherein the pulse width modulation signal includes a plurality of second switching cycles, and the first soft start phase is earlier than the second soft start phase.

10. The soft start method of the switching regulator according to claim 9, characterized in that: The output current has a plurality of rise and fall cycles, and the mode switching condition includes that the output voltage is greater than or equal to a threshold voltage, and a duration of each of the rise and fall cycles is less than a second period of each of the second switching cycles.

11. The soft start method of the switching regulator according to claim 9, wherein: The output current has multiple rise and fall cycles, and the soft start method of the switching regulator includes: A parameter value is calculated by dividing the output voltage by a predetermined inductance value, wherein the output current has a plurality of ramp-up and ramp-down cycles, and the mode switching condition includes that the parameter value is greater than or equal to a threshold, and a duration of each ramp-up and ramp-down cycle is less than a second period of each second switching cycle.

12. The soft start method of the switching regulator according to claim 9, wherein: In the first slow start phase, the output voltage increases slowly over time. In the second slow start phase, the output voltage increases rapidly over time until the output voltage reaches the predetermined voltage.

13. The soft start method of the switching regulator according to claim 9, wherein: The soft start method of the switching regulator includes: An input voltage is provided to the switching circuit via a power supply, wherein each first switching cycle of the pulse skipping modulation signal includes an on-time, and the input voltage, the output voltage, and the on-time satisfy the following relationship: (V in / L)×t on <N Where, L represents a predetermined inductance value, V in represents the input voltage, t on represents the on-time, and N represents an adjustable value ranging from 10 μA to 150 μA.

14. The soft start method of the switching regulator according to claim 9, wherein: A ratio between a first period of each of the first switching cycles and a second period of each of the second switching cycles ranges from 0.01 to 3.

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