Step-up type switching regulator

Abstract

To prevent a low-side transistor from being turned on before current flowing to a diode connected with a junction point between an inductor and the low-side transistor becomes zero.SOLUTION: A step-up type switching regulator 1 comprises: an inductor L1 the first end of which is connected with a DC power supply 2; a low-side transistor Q1; a diode D1; a detection circuit 8; and a control unit 6. In the low-side transistor Q1, a first main electrode D is connected with a second end of the inductor L1, and a second main electrode S is connected with reference potential. An anode A of the diode D1 is connected with a junction point between the second end of the inductor L1 and the first main electrode D of the low-side transistor Q1. The detection circuit 8 detects ringing which occurs in a voltage signal Vt of the anode A. The control unit 6 is connected with a control electrode G of the low-side transistor Q1 and controls on / off of the low-side transistor Q1 on the basis of a detection result of the detection circuit 8.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a step-up switching regulator. [Background technology]

[0002] BACKGROUND ART Conventionally, a boost switching regulator is known that boosts an input DC voltage and outputs the boosted DC voltage as a DC output voltage (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4974653

[0004] [overview] In a step-up switching regulator, for example, a diode is connected between the output terminal and the connection point of the inductor and the N-channel MOSFET acting as the low-side transistor. If the N-channel MOSFET turns on before the current flowing through this diode reaches zero, a parasitic bipolar transistor in the N-channel MOSFET may cause a reverse current to flow through the diode, potentially destroying it.

[0005] An object of the present disclosure is to provide a step-up switching regulator that can prevent the low-side transistor from turning on before the current flowing through a diode connected between the output terminal and the connection point of the inductor and the low-side transistor becomes zero.

[0006] In order to solve the above-mentioned problems, a step-up switching regulator according to one embodiment of the present disclosure includes an inductor, a low-side transistor, a diode, a capacitor, an output terminal, a detection circuit, and a control unit. The inductor has a first terminal connected to a DC power source 2. The low-side transistor has a first main electrode connected to a second terminal of the inductor and a second main electrode connected to a reference potential. The diode has an anode connected to a connection point between the second terminal of the inductor and the first main electrode of the low-side transistor. The capacitor is connected between the cathode of the diode and the reference potential. The output terminal is connected to the connection point between the cathode and the capacitor. The detection circuit is capable of detecting ringing occurring in a voltage signal at the anode. The control unit is connected to a control electrode of the low-side transistor and controls the on / off of the low-side transistor based on the detection result of the detection circuit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a circuit diagram showing the configuration of a main part of a step-up switching regulator according to an embodiment. [Figure 2] FIG. 2 is a time chart showing a first operation of the step-up switching regulator according to the embodiment. [Figure 3] FIG. 3 is a time chart showing a second operation of the step-up switching regulator according to the embodiment.

[0008] [Detailed explanation] Hereinafter, a step-up switching regulator 1 according to an embodiment will be described in detail with reference to the drawings. However, it should be noted that the drawings are schematic.

[0009] The embodiments described below are comprehensive or specific examples. The numerical values, components, installation positions, and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the scope of the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components.

[0010] The configuration of a step-up switching regulator 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a circuit diagram showing the configuration of a main part of a step-up switching regulator 1 according to an embodiment.

[0011] The step-up switching regulator 1 boosts an input DC voltage Vi (e.g., 5.0 V) of a DC power supply 2 connected to an input terminal 3 to generate an output DC voltage Vo, which is supplied to a load 7 via an output terminal 5. The output DC voltage Vo is set to be variable, but may also be fixed (e.g., 15.0 V). The step-up switching regulator 1 includes an inductor L1, a low-side transistor Q1, a diode D1, a capacitor C1, an output terminal 5, a control unit 6, and a detection circuit 8. The inductor L1 has an inductance of, for example, 4.7 μH. In this embodiment, the low-side transistor Q1 is an N-channel metal-oxide-semiconductor field-effect transistor (MOSFET). The first main electrode D of the low-side transistor Q1 serves as the drain, the second main electrode S serves as the source, and the control electrode G serves as the gate.

[0012] A first end of the inductor L1 is connected to the positive electrode of the DC power supply 2 via the input terminal 3. The negative electrode of the DC power supply 2 is connected to the ground, which serves as a reference potential. The DC power supply 2 applies an input DC voltage Vi to the input terminal 3. A second end of the inductor L1 is connected to a first main electrode D of the low-side transistor Q1 via the connection terminal 4. A second main electrode S of the low-side transistor Q1 is connected to the ground. A pulse-shaped control signal Vg output from the control unit 6 is input to the control electrode G of the low-side transistor Q1. The control unit 6 controls the pulse waveform of the control signal Vg so that the output DC voltage Vo output to the output terminal 5 becomes a set DC voltage value.

[0013] An anode A of a diode D1 is connected to the connection point between the second end of the inductor L1 and the first main electrode D of the low-side transistor Q1. A cathode K of the diode D1 is connected to the output terminal 5. A capacitor C1 serving as a smoothing capacitor and a load 7 are connected between the output terminal 5 and ground.

[0014] The detection circuit 8 includes a first voltage divider circuit 81, a second voltage divider circuit 82, a comparator CP1, a first input terminal 83, a second input terminal 84, and a detection signal output terminal 85. The first input terminal 83 is connected to the anode A of the diode D1, the second input terminal 84 is connected to the cathode K of the diode D1, and the detection signal output terminal 85 is connected to the control unit 6. The voltage of the anode A of the diode D1 is equal to the voltage of the connection point between the second end of the inductor L1, the first main electrode D of the low-side transistor Q1, and the anode A of the diode D1, i.e., the connection terminal voltage Vt, which is the voltage of the connection terminal 4. The voltage of the cathode K of the diode D1 is equal to the output DC voltage Vo, which is the voltage supplied to the output terminal 5 and the load 7.

[0015] The first input terminal 83 is connected to the negative input terminal (-) of the comparator CP1 via a first voltage divider circuit 81. The first voltage divider circuit 81 is a series circuit of resistors R11 and R12. A first terminal of the resistor R11 is connected to the first input terminal 83, a junction between the second terminal of the resistor R11 and the first terminal of the resistor R12 is connected to the negative input terminal (-) of the comparator CP1, and a second terminal of the resistor R12 is connected to ground. The second input terminal 84 is connected to the positive input terminal (+) of the comparator CP1 via a second voltage divider circuit 82. The second voltage divider circuit 82 is a series circuit of resistors R21 and R22. A first terminal of the resistor R21 is connected to the second input terminal 84, a junction between the second terminal of the resistor R21 and the first terminal of the resistor R22 is connected to the positive input terminal (+) of the comparator CP1, and a second terminal of the resistor R22 is connected to ground. The output terminal of the comparator CP1 is connected to a detection signal output terminal 85.

[0016] A first voltage-divided signal Vn, which is obtained by dividing the connection terminal voltage Vt using a first voltage-dividing circuit 81, is input to the negative input terminal (-) of the comparator CP1. If the voltage-dividing ratio of the first voltage-dividing circuit 81 with respect to the resistor R12 is defined as a first voltage-dividing ratio P1, then P1 = R12 / (R11 + R12), and the first voltage-divided signal Vn is expressed as Vn = P1 · Vt for the connection terminal voltage Vt. A second voltage-divided signal Vp, which is obtained by dividing the output DC voltage Vo using a second voltage-dividing circuit 82, is input to the positive input terminal (+) of the comparator CP1. If the voltage-dividing ratio of the second voltage-dividing circuit 82 with respect to the resistor R22 is defined as a second voltage-dividing ratio P2, then P2 = R22 / (R21 + R22), and the second voltage-divided signal Vp is expressed as Vp = P2 · Vo for the output DC voltage Vo.

[0017] When the diode current Id flowing through the diode D1 becomes zero, ringing occurs in the connection terminal voltage Vt. The detection circuit 8 is a circuit for detecting the ringing of the connection terminal voltage Vt to detect that the diode current Id flowing through the diode D1 has become zero. For this reason, the first voltage division ratio P1 and the second voltage division ratio P2 are set to values ​​such that the first voltage division signal Vn and the second voltage division signal Vp have appropriate magnitudes as input signals to the comparator CP1 and that the comparator CP1 can detect ringing occurring in the connection terminal voltage Vt. The detection signal Vc output from the comparator CP1 becomes a first potential signal at an L level (e.g., 0 V) ​​when no ringing is detected, and becomes a second potential signal at an H level (e.g., 1.5 V) when ringing is detected.

[0018] Next, a first operation and a second operation of the boost switching regulator 1 according to the embodiment will be described with reference to Figures 2 and 3. Figure 2 is a time chart showing the first operation of the boost switching regulator 1. Figure 3 is a time chart showing the second operation of the boost switching regulator 1.

[0019] In (1) of Figures 2 and 3, the solid line represents the connection terminal voltage Vt, i.e., the waveform of the voltage signal at the anode A of the diode D1, and the dashed line represents the output DC voltage Vo output to the output terminal 5, i.e., the waveform of the voltage signal at the cathode K of the diode D1. In (2) of Figures 2 and 3, the solid line represents the waveform of the first voltage-divided signal Vn obtained by dividing the connection terminal voltage Vt using the first voltage-divider circuit 81, and the dashed line represents the waveform of the second voltage-divided signal Vp obtained by dividing the output DC voltage Vo using the second voltage-divider circuit 82. The first voltage-divided signal Vn is input to the negative input terminal - of the comparator CP1, and the second voltage-divided signal Vp is input to the positive input terminal + of the comparator CP1. (3) of Figures 2 and 3 represents the waveform of the detection signal Vc, which is the output of the comparator CP1. The detection signal Vc becomes H level only when the first voltage-divided signal Vn becomes smaller than the second voltage-divided signal Vp due to ringing occurring in the connection terminal voltage Vt, and is L level when no ringing occurs in the connection terminal voltage Vt.

[0020] 2 and 3, (4) shows the waveform of the control signal Vg output from the control unit 6 to the control electrode G of the low-side transistor Q1. When the control signal Vg is at H level, the low-side transistor Q1 is turned on, and when it is at L level, the low-side transistor Q1 is turned off. The control signal Vg switches to L level when a predetermined gate time Tg has elapsed since it became H level. The gate time Tg is determined according to the DC voltage value set for the output DC voltage Vo.

[0021] If the detection circuit 8 detects ringing within the first set time T1 and the detection signal Vc of the comparator CP1 becomes H level, the control signal Vg rises from L level to H level when the second set time T2 has elapsed since the detection signal Vc became H level.

[0022] (5) in Figures 2 and 3 represents the mask signal Vm, which is an internal signal of the control unit 6. The mask signal Vm rises from L level to H level in synchronization with the control signal Vg rising from L level to H level, and falls from H level to L level after a mask time Tm has elapsed since the control signal Vg fell from H level to L level. When the mask signal Vm is H level, the detection signal Vc inside the control unit 6 is invalidated. (6) in Figures 2 and 3 represents the timer signal Vr, which is an internal signal of the control unit 6. The timer signal Vr outputs an H level pulse signal with a pulse width of pulse time Tp (e.g., 0.1 μs) when a first set time T1 (e.g., 2.4 μs) has elapsed since the control signal Vg fell from H level to L level.

[0023] If the detection circuit 8 does not detect ringing within the first set time T1 and the detection signal Vc of the comparator CP1 remains at L level, the control signal Vg rises from L level to H level in synchronization with the timer signal Vr falling from H level to L level.

[0024] In (7) of FIGS. 2 and 3, the dashed line represents the inductor current IL flowing from the inductor L1 to the connection terminal 4, and the solid line represents the waveform of the diode current Id flowing inside the diode D1.

[0025] First, a first operation of the step-up switching regulator 1 shown in Fig. 1 will be described with reference to Fig. 2. The first operation will be described as the operation performed immediately after the step-up switching regulator 1 starts operating, when the input DC voltage Vi is 5.0 V, the output DC voltage Vo is 13.0 V, which is lower than the specified 15.0 V, and no ringing occurs in the connection terminal voltage Vt. In the first operation, no ringing occurs in the connection terminal voltage Vt within the first set time T1, and therefore the detection signal Vc does not go high within the first set time T1.

[0026] 2, at time t11, the control signal Vg changes from low to high. This causes the low-side transistor Q1 to switch from off to on, causing the inductor current IL to flow from the second end of the inductor L1 to ground via the connection terminal 4 and the low-side transistor Q1, and IL begins to increase from zero. At this time, the connection terminal voltage Vt and the diode current Id become zero.

[0027] Then, after the gate time Tg (here, Tg = 0.24 μs) has elapsed and the time t12 has arrived, the control signal Vg switches from H level to L level, and the low-side transistor Q1 switches from ON to OFF. Then, the inductor current IL flows to the output terminal 5 via the diode D1, and the inductor current IL and the diode current Id become equal. The connection terminal voltage Vt changes from zero to a predetermined voltage value determined by the input DC voltage Vi, the inductance of the inductor L1, the gate time Tg, and other factors. The output DC voltage Vo is smoothed by the capacitor C1 and remains constant. When the control signal Vg switches from L level to H level, an H-level pulse is generated in the detection signal Vc. However, during the period between the gate time Tg and the mask time Tm (here, Tm = 0.28 μs), the mask signal Vm is H level, and the detection signal Vc is invalid.

[0028] Then, after the control signal Vg switches from H level to L level at time t12, the detection circuit 8 does not detect the occurrence of ringing in the connection terminal voltage Vt within the first set time T1 (here, T1 = 2.4 μs). Then, at time t13, when the first set time T1 has elapsed since time t12, the timer signal Vr switches from L level to H level. Here, the first set time T1 is set to a value that ensures that the diode current Id becomes zero after the control signal Vg switches from H level to L level. The first set time T1 may be set based on the results of experiments, simulations, or the like obtained in advance.

[0029] When a pulse time Tp (here, Tp=0.1 μs) has elapsed from time t13 and the timer signal Vr switches from H level to L level at time t14, the control signal Vg switches from L level to H level in synchronization with this. The operation from time t14 to time t15 is the same as the operation from time t11 to time t12, and the operation after time t15 is the same as the operation after time t12, so a description of the operation after time t14 will be omitted.

[0030] As described above, in the first operation, ringing does not occur in the connection terminal voltage Vt, and therefore the detection circuit 8 does not output the detection signal Vc during the first set time T1. However, because the first set time T1 is set to a value that ensures that the diode current Id becomes zero after the control signal Vg switches from H level to L level, the low-side transistor Q1 does not turn on when the diode current Id is flowing. Therefore, because the low-side transistor Q1 is prevented from turning on when the diode current Id is flowing, a reverse current does not flow through the diode D1, which could destroy the diode D1.

[0031] Next, a second operation of the step-up switching regulator 1 shown in Fig. 1 will be described with reference to Fig. 3. The second operation will be described as an operation when ringing occurs in the connection terminal voltage Vt when the input DC voltage Vi is 5.0 V, the output DC voltage Vo is the specified 15.0 V, and the diode current Id becomes zero. In the second operation, ringing occurs in the connection terminal voltage Vt within the first set time T1, and therefore the detection signal Vc becomes H level within the first set time T1.

[0032] 3, at time t21, the control signal Vg changes from low to high. This causes the low-side transistor Q1 to switch from off to on, causing the inductor current IL to flow from the second end of the inductor L1 to ground via the connection terminal 4 and the low-side transistor Q1, and IL begins to increase from zero. At this time, the connection terminal voltage Vt and the diode current Id become zero.

[0033] Then, after the gate time Tg (here, Tg = 0.24 μs) has elapsed and the time t22 has arrived, the control signal Vg switches from H level to L level, and the low-side transistor Q1 switches from ON to OFF. Then, the inductor current IL flows to the output terminal 5 via the diode D1, and the inductor current IL and the diode current Id become equal. The connection terminal voltage Vt changes from zero to a predetermined voltage value determined by the input DC voltage Vi, the inductance of the inductor L1, the gate time Tg, and other factors. The output DC voltage Vo is smoothed by the capacitor C1 and remains constant. When the control signal Vg switches from L level to H level, an H-level pulse is generated in the detection signal Vc. However, during the period between the gate time Tg and the mask time Tm (here, Tm = 0.28 μs), the mask signal Vm is H level, and the detection signal Vc is invalid.

[0034] Then, after the control signal Vg switches from H level to L level at time t22, the detection circuit 8 detects that ringing has occurred in the connection terminal voltage Vt within the first set time T1 (here, T1 = 2.4 μs). That is, when the diode current Id of the diode D1 becomes zero, ringing occurs in the connection terminal voltage Vt. Then, ringing occurs in the connection terminal voltage Vt, and at time t23, the detection signal Vc changes from L level to H level during the period in which the first voltage-divided signal Vn of the comparator CP1 becomes smaller than the second voltage-divided signal Vp.

[0035] After the detection signal Vc switches from L level to H level, the control signal Vg switches from L level to H level at time t24, which is the second set time T2 (here, T2=0.65 μs) has elapsed. The operation after time t24 is the same as the operation after time t21, so a description of the operation after time t24 will be omitted.

[0036] In this way, in the second operation, the diode current Id becomes zero within the first set time T1, and the detection circuit 8 detects that ringing has occurred in the connection terminal voltage Vt, and based on this, the control signal Vg switches from L level to H level. In other words, the low-side transistor Q1 does not turn on when the diode current Id is flowing. Therefore, because the low-side transistor Q1 is prevented from turning on when the diode current Id is flowing, a reverse current does not flow through the diode D1, which would destroy the diode D1.

[0037] Furthermore, in the second operation, after the control signal Vg switches from H level to L level, the control signal Vg switches from L level to H level before the first set time T1 is reached. Therefore, in the second operation, the time during which the low-side transistor Q1 is off can be made shorter than in the first operation, and the step-up switching regulator 1 can be operated with higher efficiency.

[0038] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0039] (Addendum) The technical ideas that can be understood from the present disclosure are described below. Note that, for the purpose of aiding understanding and not intending to be limiting, the components described in the appendices are given the reference numerals of the corresponding components in the embodiments. The reference numerals are shown as examples to aid understanding, and the components described in each appendix should not be limited to the components indicated by the reference numerals.

[0040] (Appendix 1) The step-up switching regulator 1 includes an inductor L1, a low-side transistor Q1, a diode D1, an output terminal 5, a detection circuit 8, and a control unit 6. The inductor L1 has a first terminal connected to a DC power supply 2. The low-side transistor Q1 has a first main electrode D connected to a second terminal of the inductor L1 and a second main electrode S connected to a reference potential GND. The diode D1 has an anode A connected to the connection point between the second terminal of the inductor L1 and the first main electrode D of the low-side transistor Q1. The capacitor C1 is connected between the cathode K of the diode D1 and the reference potential GND. The output terminal 5 is connected to the connection point between the cathode K and the capacitor C1. The detection circuit 8 is capable of detecting ringing occurring in the voltage signal Vt at the anode A. The control unit 6 is connected to the control electrode G of the low-side transistor Q1 and controls the on / off of the low-side transistor Q1 based on the detection result of the detection circuit 8.

[0041] The step-up switching regulator 1 described in Supplementary Note 1 can prevent the low-side transistor Q1 from turning on before the diode current Id flowing through the diode D1 becomes zero. Therefore, the step-up switching regulator 1 described in Supplementary Note 1 does not allow a reverse current to flow through the diode D1 and destroy the diode D1.

[0042] (Appendix 2) In the step-up switching regulator 1 described in Supplementary Note 1, the control unit 6 performs the following control. If the detection circuit 8 does not detect ringing within a predetermined first set time T1 after the low-side transistor Q1 is turned off, the control unit 6 controls the low-side transistor Q1 to be turned on after the first set time T1 has elapsed. Furthermore, if the detection circuit 8 detects ringing within the first set time T1 after the low-side transistor Q1 is turned off, the control unit 6 controls the low-side transistor Q1 to be turned on after the detection circuit 8 detects the ringing.

[0043] According to the step-up switching regulator 1 described in Supplementary Note 2, the time during which the low-side transistor Q1 is off can be shortened, and the step-up switching regulator 1 can be operated with higher efficiency.

[0044] (Appendix 3) In the step-up switching regulator 1 described in Appendix 2, the detection circuit 8 includes a first voltage-dividing circuit 81, a second voltage-dividing circuit 82, and a comparator CP1. The first voltage-dividing circuit 81 is a series circuit of a first resistor R11 and a second resistor R12 connected between the anode A and a reference potential. The second voltage-dividing circuit 82 is a series circuit of a third resistor R21 and a fourth resistor R22 connected between the cathode K and the reference potential. A first input terminal (-) of the comparator CP1 is connected to the connection point between the first resistor R11 and the second resistor R12, and receives a first voltage-divided signal Vn obtained by dividing the voltage signal Vt of the anode A by the first voltage-dividing circuit 81. A second input terminal (+) of the comparator CP1 is connected to the connection point between the third resistor R21 and the fourth resistor R22, and receives a second voltage-divided signal Vp obtained by dividing the voltage signal Vo of the cathode K by the second voltage-dividing circuit 82. The resistance values ​​of the first resistor R11, the second resistor R12, the third resistor R21, and the fourth resistor R22 are set so that the comparator CP1 outputs a first potential signal L when no ringing is detected and outputs a second potential signal H when ringing is detected. If the detection circuit 8 does not output the second potential signal H within a first set time T1 after turning off the low-side transistor Q1, the control unit 6 turns on the low-side transistor Q1 after the first set time T1 has elapsed. Furthermore, if the detection circuit 8 outputs the second potential signal H within the first set time T1 after turning off the low-side transistor Q1, the control unit 6 controls the low-side transistor Q1 to turn on after the detection circuit 8 outputs the second potential signal H.

[0045] (Appendix 4) In the step-up switching regulator 1 described in Supplementary Note 2, the control unit 6 turns off the low-side transistor Q1 after a predetermined gate time Tg has elapsed since the low-side transistor Q1 was turned on.

[0046] (Appendix 5) In the step-up switching regulator 1 described in any one of Supplementary Notes 1 to 4, the low-side transistor Q1 is an N-channel MOSFET, with the first main electrode D as the drain, the second main electrode S as the source, and the control electrode G as the gate. [Explanation of symbols]

[0047] 1. Step-up switching regulator 2 DC power supply 3 Input terminals 4 Connection terminal 5 Output terminal 6 Control Unit 7 Load 8 Detection circuit 81 1st voltage divider circuit 82 Second voltage divider circuit 83 First input terminal 84 Second input terminal 85 Detection signal output terminal A Anode C1 capacitor CP1 Comparator D1 Diode D First main electrode (drain) G Control electrode (gate) IL Inductor current Id Diode current K cathode L1 inductor Q1 Low-side transistor R11,R12,R21,R22 Resistor S Second main electrode (source) T1 First setting time T2 Second setting time Tm Mask time Tg Gate time Tp Pulse time Vc detection signal Vg control signal Vi Input DC voltage Vm mask signal Vn 1st voltage divider signal Vo: DC output voltage (cathode voltage signal) Vp Second divided voltage signal Vr timer signal Vt Connection terminal voltage (anode voltage signal)

Claims

1. an inductor having a first end connected to a DC power source; a low-side transistor having a first main electrode connected to the second end of the inductor and a second main electrode connected to a reference potential; a diode having an anode connected to a connection point between the second end of the inductor and the first main electrode of the low-side transistor; a capacitor connected between the cathode of the diode and the reference potential; an output terminal connected to a connection point between the cathode and the capacitor; a detection circuit capable of detecting ringing occurring in the voltage signal of the anode; a control unit connected to a control electrode of the low-side transistor and controlling the on / off of the low-side transistor based on a detection result of the detection circuit; A step-up switching regulator equipped with a

2. 2. The step-up switching regulator according to claim 1, wherein, if the detection circuit does not detect the ringing within a predetermined first set time after turning off the low-side transistor, the control unit controls to turn on the low-side transistor after the first set time has elapsed, and if the detection circuit detects the ringing within the first set time after turning off the low-side transistor, the control unit controls to turn on the low-side transistor after the detection circuit detects the ringing.

3. The detection circuit a first voltage dividing circuit which is a series circuit of a first resistor and a second resistor connected between the anode and the reference potential; a second voltage dividing circuit which is a series circuit of a third resistor and a fourth resistor connected between the cathode and the reference potential; a comparator having a first input terminal connected to the connection point between the first resistor and the second resistor, and receiving a first divided voltage signal obtained by dividing the anode voltage signal by the first voltage divider circuit, and a second input terminal connected to the connection point between the third resistor and the fourth resistor, and receiving a second divided voltage signal obtained by dividing the cathode voltage signal by the second voltage divider circuit; Equipped with resistance values ​​of the first resistor, the second resistor, the third resistor, and the fourth resistor are set to values ​​that cause the comparator to output a first potential signal when the ringing is not detected, and to output a second potential signal when the ringing is detected; the control unit controls so that, if the detection circuit does not output the second potential signal within the first set time range after turning off the low-side transistor, the control unit turns on the low-side transistor after the first set time has elapsed, and, if the detection circuit outputs the second potential signal within the first set time range after turning off the low-side transistor, the control unit turns on the low-side transistor after the detection circuit outputs the second potential signal.

3. The step-up switching regulator according to claim 2.

4. 3. The step-up switching regulator according to claim 2, wherein the control unit turns off the low-side transistor after a predetermined gate time has elapsed since the low-side transistor was turned on.

5. 5. The step-up switching regulator according to claim 1, wherein the low-side transistor is an N-channel MOSFET, the first main electrode is a drain, the second main electrode is a source, and the control electrode is a gate.

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