Semiconductor integrated circuit

Abstract

To provide a semiconductor integrated circuit that enables appropriate short circuit detection.SOLUTION: A ground fault detection circuit 240, which is a short circuit detection circuit, is enabled while one of a low-side transistor ML and a high-side transistor MH, which is the one being monitored, MH, is on, and determines that a short circuit has occurred when a current IMH flowing through the monitored transistor MH exceeds a threshold current ITHH. The threshold current ITHH periodically repeats fluctuations, taking a relatively large first value ITH1 during a relatively long first period TH and a relatively small second value ITH2 during a relatively short second period TL.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to semiconductor integrated circuits. [Background technology]

[0002] Semiconductor integrated circuits such as class-D amplifiers, DC / DC converters, and motor drivers include switching circuits (inverters) that include high-side and low-side transistors.

[0003] If the output node of the switching circuit is shorted to power (shorted to the power supply line) and the low-side transistor is turned on, an overcurrent will flow through the low-side transistor. For this reason, a power short detection circuit may be provided in a semiconductor integrated circuit. Similarly, if the output node of the switching circuit is shorted to ground (shorted to earth) and the high-side transistor is turned on, an overcurrent will flow through the high-side transistor. For this reason, a ground fault detection circuit may be provided in a semiconductor integrated circuit. In this specification, power short detection and ground short detection are collectively referred to as short circuit detection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-195535

[0005] In a Class D amplifier or DC / DC converter, an LC filter including an output inductor and an output capacitor is connected to the output terminal of the switching circuit. Immediately after the switching circuit starts up, the voltage of the output capacitor is zero, and when the switching circuit performs PWM operation at startup, the output capacitor is charged with LC resonance. At this time, the current I that flows through the switching circuit START (for example, 6.5A) is the current I that flows during normal operation. NORM (for example, 2.5A).

[0006] The fusing current of the bonding wire is I MAX(CONT) , when applied instantaneously (for example, 1 ms), I MAX(INS) For example, I MAX(CONT) is 5A, I MAX(INS) is 10A.

[0007] The inventors have determined that the short circuit detection threshold I TH We considered setting different current values for

[0008] Specifically, during the startup period, the short detection threshold I TH(START) I START TH(START) MAX(INS) ) is set high so as to satisfy the short detection threshold I TH(NORM) I NORM TH(NORM) MAX(CONT) ) is set to satisfy

[0009] In this case, during normal operation, I MAX(CONT) <I<I MAX(INS) When a current that satisfies the above requirement flows, even though the bonding wire does not melt, it is determined to be a short circuit abnormality, resulting in overprotection.

[0010] [overview] It is within this context that the present disclosure has been made.

[0011] ​​​​A semiconductor integrated circuit according to an embodiment of the present disclosure includes a power supply line, an output line, and a ground line, an output stage including a high-side transistor connected between the power supply line and the output line and a low-side transistor connected between the output line and the ground line, and a short-circuit detection circuit that determines a short-circuit state when one of the low-side transistor and the high-side transistor, which is to be monitored, is enabled during an on-period and a current flowing through the monitored transistor exceeds a threshold current. The threshold current periodically repeats a fluctuation in which it has a relatively large first value for a relatively long first period and a relatively small second value for a relatively short second period. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a circuit diagram of a semiconductor integrated circuit according to an embodiment. [Figure 2] FIG. 2 is a functional block diagram related to short circuit detection in the semiconductor integrated circuit according to the embodiment. [Figure 3] FIG. 3 is a diagram illustrating the operation of the semiconductor integrated circuit at the time of startup. [Figure 4] FIG. 4 is a diagram illustrating the control of the threshold current in a semiconductor integrated circuit. [Figure 5] FIG. 5 is a diagram illustrating ground fault detection in the ground fault detection circuit. [Figure 6] FIG. 6 is a diagram illustrating ground fault detection in the ground fault detection circuit. [Figure 7] FIG. 7 is a circuit diagram showing an example of the configuration of a semiconductor integrated circuit. [Figure 8] FIG. 8 is a circuit diagram of a short-to-power detection circuit and a threshold voltage source according to the embodiment. [Figure 9] FIG. 9 is a circuit diagram illustrating power short detection by the power short detection circuit. [Figure 10] FIG. 10 is a circuit diagram of a ground fault detection circuit according to the embodiment. [Figure 11] FIG. 11 is a block diagram of an audio system. [Figure 12]FIG. 12 is a block diagram of a step-down converter.

[0013] [Detailed explanation] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0014] A semiconductor integrated circuit according to one embodiment includes a power supply line, an output line, and a ground line; an output stage including a high-side transistor connected between the power supply line and the output line and a low-side transistor connected between the output line and the ground line; and a short-circuit detection circuit configured to determine a short-circuit state when one of the low-side transistor and the high-side transistor, which is monitored, is enabled while the other is on and a current flowing through the monitored transistor exceeds a threshold current. The threshold current periodically repeats a fluctuation in which it has a relatively large first value for a relatively long first period and a relatively small second value for a relatively short second period.

[0015] For example, the sum of the first and second periods, i.e., the fluctuation period of the threshold current, can be set to be approximately the same as the tolerable time of an instantaneous overcurrent. The first value can be set based on the threshold value of the instantaneous overcurrent, and the second value can be set based on the threshold value of a continuous overcurrent.

[0016] According to this embodiment, during normal operation, it is possible to detect both a case where the low overcurrent threshold value is continuously exceeded and a case where the high overcurrent threshold value is momentarily exceeded.

[0017] In one embodiment, when the switching period of the output stage is Ts, the length of the second period may be 1Ts to 10Ts.

[0018] In one embodiment, the sum of the first period and the second period may be 0.5 ms to 1 ms.

[0019] In one embodiment, the short detection circuit may include a detection voltage generation circuit that converts the current flowing through the transistor to be monitored into a detection voltage, and a determination circuit that compares the detection voltage with a threshold voltage that defines a threshold current, and asserts a short detection signal when the detection voltage exceeds the threshold voltage.

[0020] In one embodiment, the circuit may further include a threshold voltage source that generates a threshold voltage that assumes a first voltage level in a first period and a second voltage level in a second period.

[0021] In one embodiment, the monitored transistor is a high-side transistor and the short detection circuit may perform ground fault detection.

[0022] In one embodiment, the detection voltage generation circuit includes a first resistor having a first end connected to a ground line, a second resistor having a first end connected to the ground line, a first switch connected between a second end of the first resistor and the output line and turned on when the low-side transistor is on, a first current source, a first N-type transistor having a first electrode connected to the second end of the first resistor and a control electrode connected to the first current source and a second electrode, a second N-type transistor having a first electrode connected to the second end of the second resistor and a control electrode connected to the control electrode of the first transistor, and a third resistor provided on a path of a detection current proportional to a current flowing through the second transistor, and a voltage drop across the third resistor may be the detection voltage.

[0023] In one embodiment, the detection voltage generating circuit may further include a second switch connected between the second end of the first resistor and the ground line, the second switch being turned on when the low-side transistor is off.

[0024] In one embodiment, the monitored transistor is a low-side transistor, and the short detection circuit may perform short-to-power detection.

[0025] In one embodiment, the detection voltage generation circuit includes a fifth resistor having a first end connected to the power supply line, a sixth resistor having a first end connected to the power supply line, a third switch connected between a second end of the fifth resistor and the output line and turned on when the high-side transistor is on, a third current source, a third P-type transistor having a first electrode connected to the second end of the fifth resistor and a control electrode connected to the third current source and a second electrode, a fourth P-type transistor having a first electrode connected to the second end of the sixth resistor and a control electrode connected to the control electrode of the third transistor, and a seventh resistor provided on a path of a detection current proportional to a current flowing through the fourth transistor, wherein a voltage drop across the seventh resistor may be the detection voltage.

[0026] In one embodiment, the detection voltage generating circuit may further include a fourth switch connected between the second end of the fifth resistor and the power supply line, and turned on when the high-side transistor is off.

[0027] In one embodiment, the threshold voltage source may include a reference voltage source that generates a reference voltage and a variable gain amplifier that amplifies the reference voltage with a gain that is a first value during a first period and a second value during a second period.

[0028] In one embodiment, the threshold voltage source may include a reference voltage source that generates a reference voltage that has a first level in a first period and a second level in a second period, and an amplifier that amplifies the reference voltage.

[0029] In one embodiment, the reference voltage source may include a second current source that generates a reference current, and a series-connected circuit that includes a fourth resistor connected in series on the path of the reference current and a MOS (Metal Oxide Semiconductor) transistor whose gate is biased at a constant voltage, and may output a threshold voltage according to the voltage drop of the series-connected circuit.

[0030] In one embodiment, the semiconductor integrated circuit may be an audio class D amplifier.

[0031] In one embodiment, the semiconductor integrated circuit may be a switching regulator.

[0032] In one embodiment, the semiconductor integrated circuit may be for use in a vehicle.

[0033] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted as appropriate. Furthermore, the embodiments are examples and do not limit the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

[0034] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the function or effect achieved by their connection.

[0035] Similarly, "a state in which component C is connected (provided) between component A and component B" includes not only a case in which component A and component C, or component B and component C, are directly connected, but also a case in which they are indirectly connected via other components that do not substantially affect the electrical connection state between them or that do not impair the function or effect achieved by their combination.

[0036] In addition, in this specification, symbols attached to electrical signals such as voltage signals and current signals, or circuit elements such as resistors, capacitors, and inductors, represent the respective voltage values, current values, or circuit constants (resistance values, capacitance values, inductances) as necessary.

[0037] 1 is a circuit diagram of a semiconductor integrated circuit 200 according to an embodiment. The semiconductor integrated circuit 200 has a power supply terminal VCC, a switching terminal SW, a ground terminal GND, and a bootstrap terminal BS. The power supply terminal VCC receives a power supply voltage (input voltage) V CC is supplied to the switching terminal SW, and the ground terminal GND is grounded. An inductive element such as a speaker coil, a motor coil, or an inductor is connected to the switching terminal SW. A bootstrap capacitor C is connected between the bootstrap terminal BS and the switching terminal SW. BS The switching terminal SW is connected to the external inductor L OUT and capacitor C OUT is connected.

[0038] The semiconductor integrated circuit 200 supplies a high-level voltage V CC , a low level voltage of 0V, or a high impedance state.

[0039] The semiconductor integrated circuit 200 includes a power supply line 202, an output line (also called a switching line) 204, a ground line 206, a bootstrap line 208, a rectifying element 209, a high-side driver 210, a low-side driver 220, a level shifter 230, a ground fault detection circuit 240, and a power fault detection circuit 260. The ground fault detection circuit 240 and the power fault detection circuit 260 are collectively referred to as short detection circuits.

[0040] The power supply line 202 is connected to a power supply terminal VCC. The output line 204 is connected to a switching terminal SW. The ground line 206 is connected to a ground terminal GND. The bootstrap line 208 is connected to a bootstrap terminal BS. A constant voltage V generated by a power supply circuit (not shown) is applied to the bootstrap terminal BS via a rectifier element 209. REG The rectifying element 209 has a cathode connected to the bootstrap line 208 and an anode connected to a constant voltage V REG The rectifying element 209 may be a synchronous rectifying switch that switches in synchronization with the high-side transistor MH. BS forms a bootstrap circuit, and a bootstrap line 208 is connected to the switching terminal SW (output line 204) via a switching voltage V SW than V REG -Vf higher bootstrap voltage V BS Vf is the forward voltage of the rectifying element 209.

[0041] The high-side transistor MH and the low-side transistor ML are N-channel metal oxide semiconductor field effect transistors (MOSFETs). The high-side transistor MH is connected between a power supply line 202 and an output line 204, and the low-side transistor ML is connected between the output line 204 and a ground line 206.

[0042] The level shifter 230 level-shifts the control signal HIN and passes it to the high-side driver 210. The high-side driver 210 drives the high-side transistor MH in response to the control signal HIN. The low-side driver 220 drives the low-side transistor ML in response to the control signal LIN.

[0043] When the high-side transistor MH is on and the low-side transistor ML is off, the switching voltage V SW is the high-level voltage VCC When the high-side transistor MH is off and the low-side transistor ML is on, the switching voltage V SW is a low-level voltage of 0 V. When both the high-side transistor MH and the low-side transistor ML are off, the switching terminal SW is in a high impedance state.

[0044] The power short detection circuit 260 is enabled in a low output state in which the high-side transistor MH is off and the low-side transistor ML is on. In the enabled state, the power short detection circuit 260 can detect a power short abnormality at the switching terminal SW, and when it detects a power short abnormality, it asserts a power short detection signal SDET (for example, to a high level). Specifically, the power short detection circuit 260 detects the current I flowing through the low-side transistor ML while the low-side transistor ML is on. ML The monitored current is monitored until the threshold current I THL If the voltage exceeds this threshold, it is determined that a short-to-power anomaly has occurred. The short-to-power detection circuit 260 is supplied with the gate signal of the low-side transistor ML as an active-high enable signal EN.

[0045] The ground fault detection circuit 240 is enabled in a high output state in which the high-side transistor MH is on and the low-side transistor ML is off. In the enabled state, the ground fault detection circuit 240 can detect a ground fault abnormality at the switching terminal SW, and when a ground fault abnormality is detected, the ground fault detection circuit 240 asserts (for example, high level) the ground fault detection signal GDET. Specifically, the ground fault detection circuit 240 detects the current I flowing through the high-side transistor MH while the high-side transistor MH is on. MH The monitored current is monitored until the threshold current I THH If the difference exceeds this value, it is determined that a ground fault has occurred. The ground fault detection circuit 240 is supplied with the gate signal of the high-side transistor MH as an active-high enable signal EN.

[0046] FIG. 2 is a functional block diagram related to short circuit detection in the semiconductor integrated circuit 200 according to the embodiment.

[0047] The ground fault detection circuit 240 monitors the high-side transistor MH and is enabled while the high-side transistor MH is on. The ground fault detection circuit 240 detects the current I MH is the threshold current I THH If it exceeds this value, it is determined to be in a short state (ground fault abnormality) and the ground fault detection signal GDET is asserted.

[0048] The power short detection circuit 260 monitors the low-side transistor ML and is enabled while the low-side transistor ML is on. The power short detection circuit 260 detects the current I ML is the threshold current I THL If this value exceeds 1, it is determined to be in a short state (power short abnormality) and the power short detection signal SDET is asserted.

[0049] In the ground fault detection circuit 240 and the power fault detection circuit 260, the threshold current I THH ,I THL Specifically, in the ground fault detection circuit 240, the threshold current I THH is the relatively long first period T H While, the relatively large first value I H1 and a relatively short second period T L While, a relatively small second value I H2 The threshold current I THH The fluctuation period T is T H +T L This becomes:

[0050] Similarly, in the power short detection circuit 260, the threshold current I THL is the relatively long first period T H While, the relatively large first value I L1 and a relatively short second period T L While, a relatively small second value I L2 The threshold current I THL The fluctuation period T is also T H +T L This becomes:

[0051] Overcurrent conditions in semiconductor integrated circuits can be broadly divided into two types. One is when the circuit current increases instantaneously (for a period of time T INS ) and the upper limit of the allowable current (instantaneous threshold I TH(INS) ) is an overcurrent state. The other is when the circuit current exceeds the continuous threshold I TH(CONT) This is an overcurrent condition exceeding

[0052] For example, two overcurrent conditions can be defined based on the melting of a bonding wire. The melting current of a bonding wire is I MAX(CONT) , instantaneous application (for example, T INS = 1 ms) MAX(INS) In this case, I TH(INS) Considering the detection error and margin, I MAX(INS) It is set to a value slightly lower than I TH(CONT) Considering the detection error and margin, I MAX(CONT) is set to a small value slightly lower than

[0053] The threshold current I of the ground fault detection circuit 240 and the power fault detection circuit 260 TH The first value I L1 ,I H1 I MAX(INS) and the second value I L2 ,I H2 I MAX(CONT) can be associated with

[0054] Also, the threshold current I TH The fluctuation period of T(=T H +T L ) is T INS can be determined based on T INS It is preferable to set the period T equal to or shorter than this. Typically, the period T can be set to 0.5 ms to 1 ms. After setting the period T, H and the second period T L The length of T H +T L =T T H >T L The second period T L The length of the voltage V generated at the switching terminal SW SW It may be set to be an integer multiple of the switching period (PWM period) Ts. L can be generated by a digital circuit, eliminating the need for analog timers. For example, T L can be set to about 1Ts to 10Ts.

[0055] The above is the configuration of the semiconductor integrated circuit 200. Next, the operation thereof will be described.

[0056] 3 is a diagram illustrating the operation of the semiconductor integrated circuit 200 at startup. Time t0 is the startup start time. When the switching of the high-side transistor MH and the low-side transistor ML starts at time t0, the switching voltage V SW is high level (V IN ) and low level (0V) alternately. The inductor L connected to the switching terminal SW OUT and capacitor C OUT forms an LC resonant circuit, the output current I OUT Resonates. Capacitor C OUT The output voltage V OUT The output voltage V OUT The period until the temperature stabilizes is called the start-up period T START The startup period T START The length is, for example, about 0.6 ms to 1 ms.

[0057] FIG. 4 shows the threshold current I THH ,I THL As described above, the threshold current I THH , the threshold current for earth fault detection I THL Immediately after the start-up, the threshold current I THH ,I THLis the first value I H1 ,I L1 The first period T H The length of the startup period T START This allows the startup period T START At this point, the resonant output current I OUT This can prevent the current from being erroneously determined as an overcurrent.

[0058] The threshold values of the ground fault detection circuit 240 and the power fault detection circuit 260 may be the same or different. H1 =I L1 , I H2 =I L2 may or may not be true.

[0059] 5 is a diagram illustrating the detection of a ground fault in the ground fault detection circuit 240. FIG. 5 shows how an instantaneous ground fault is detected. When an instantaneous ground fault occurs, a current I MH becomes larger, and the threshold current I THH The first value I H1 The earth fault duration is typically greater than the second period T L Because the time is longer, the ground fault detection circuit 240 can reliably detect a ground fault state regardless of the timing at which the ground fault occurs, and the ground fault detection signal GDET is asserted.

[0060] 6 is a diagram illustrating the detection of a ground fault in the ground fault detection circuit 240. FIG. 6 shows how a long-term ground fault is detected. When a ground fault occurs over a long period of time, the current I flowing through the high-side transistor MH MH becomes larger, and the threshold current I THH The second value of I H2 Therefore, the second period T L , the ground fault detection circuit 240 can reliably detect a ground fault condition, and the ground fault detection signal GDET is asserted.

[0061] The power short detection by the power short detection circuit 260 is similar.

[0062] As described above, the semiconductor integrated circuit 200 according to the embodiment can reliably detect both instantaneous ground faults and power faults, and long-term ground faults and power faults. H During this time, the monitored current is above the threshold I H2 ,I L2 Even if the current exceeds this limit, it is not judged as an overcurrent, so there is no overprotection.

[0063] The present disclosure covers various devices and methods that can be understood as the block diagram or circuit diagram of Figure 2 or derived from the above description, and is not limited to a specific configuration. Below, more specific configuration examples and examples will be described not to narrow the scope of the present disclosure, but to aid in understanding and clarify the essence and operation of the present disclosure and the present invention.

[0064] 7 is a circuit diagram showing an example of the configuration of the semiconductor integrated circuit 200. The ground fault detection circuit 240 includes a detection voltage generation circuit 241 and a determination circuit 250. The detection voltage generation circuit 241 detects a current I flowing through the high-side transistor MH to be monitored. MH is converted into the detection voltage VdetH. VdetH=I MH ×α α is the conversion gain of the detection voltage generating circuit 241.

[0065] The determination circuit 250 calculates the detection voltage VdetH based on the threshold current I THH When the detection voltage VdetH exceeds the threshold voltage Vth, the ground fault detection signal GDET is asserted.

[0066] In this configuration, the threshold current I THH is expressed by the following formula: I THH =Vth / α

[0067] The power fault detection circuit 260 is configured similarly to the ground fault detection circuit 240, and includes a detection voltage generation circuit 261 and a determination circuit 270. The detection voltage generation circuit 261 detects a current I flowing through the low-side transistor ML to be monitored. ML is converted into the detection voltage VdetL. VdetL=I ML ×β β is the conversion gain of the detection voltage generating circuit 261.

[0068] The determination circuit 270 calculates the detection voltage VdetL based on the threshold current I THL When the detection voltage VdetL exceeds the threshold voltage Vth, the power short detection signal SDET is asserted.

[0069] In this configuration, the threshold current I THL is expressed by the following formula: I THL =Vth / β

[0070] In this embodiment, the threshold current I THH ,I THL In order to switch between two values, the threshold voltage Vth is changed in a time-division manner.

[0071] The threshold voltage source 290 supplies a threshold voltage Vth to the power fault detection circuit 260 and the ground fault detection circuit 240. The controller 291 changes the threshold voltage Vth between two voltage levels Vth1 and Vth2 in synchronization with the clock signal CLK. Specifically, during the first period T H During the second period T L During this time, the threshold voltage Vth becomes a relatively small second value Vth2.

[0072] 8 is a circuit diagram of a power short detection circuit 260 and a threshold voltage source 290 according to the embodiment. First, the power short detection circuit 260 will be described.

[0073] The power short detection circuit 260 detects the constant voltage V REGDThe detection voltage generating circuit 261 includes a first switch SW11, a second switch SW12, a first current source 262, a first resistor R11, a second resistor R12, a first transistor Q11, a second transistor Q12, and a current mirror circuit 264.

[0074] A first end of the first resistor R11 is connected to the ground line 206. A first end of the second resistor R12 is connected to the ground line 206.

[0075] The first switch SW11 is connected between the second end of the first resistor R11 and the output line 204. The first switch SW11 is turned on when the low-side transistor ML is on. For example, the first switch SW11 is an NMOS transistor, and the gate of the first switch SW11 is supplied with the gate signal of the low-side transistor ML.

[0076] The second switch SW12 is connected between the ground line 206 and the second end of the first resistor R11, and is turned on when the low-side transistor ML is turned off.

[0077] When the first switch SW11 is on and the second switch SW12 is off, the power short detection circuit 260 is enabled. When the first switch SW11 is off and the second switch SW12 is on, the power short detection circuit 260 is disabled.

[0078] The first transistor Q11 is an NPN bipolar transistor, and has a first electrode (emitter) connected to the second end of the first resistor R11. A second electrode (collector) and a control electrode (base) of the first transistor Q11 are connected to the first current source 262. The first current source 262 includes, for example, a reference current source 263 and a current mirror circuit CM10, and sources a constant current Ic.

[0079] The second transistor Q12 is an NPN bipolar transistor of the same type as the first transistor Q11, and has a first electrode (emitter) connected to the second end of the second resistor R12 and a control electrode (base) connected to the control electrode (base) of the first transistor Q11.

[0080] The current mirror circuit 264 mirrors the current Idet flowing through the second transistor Q12.

[0081] The third resistor R13 is connected between the output node 265 of the current mirror circuit 264 and the ground line 206. A voltage drop proportional to the output current Idet' of the current mirror circuit 264 occurs across the third resistor R13. VdetL=R13×Idet' …(1)

[0082] The determination circuit 270 generates a power short detection signal SDET based on the result of comparing the voltage drop (detection voltage) VdetL across the third resistor R13 with a predetermined threshold voltage Vth. Specifically, the determination circuit 270 asserts the power short detection signal SDET when VdetL>Vth.

[0083] In this embodiment, the determination circuit 270 includes a comparator 272, a filter 274, a filter 276, and an AND gate 278. The comparator 272 compares the detection voltage VdetL with the threshold voltage Vth. The filter 274 is a low-pass filter that removes high-frequency components from the output signal COMP of the comparator 272. Noise components are removed by the filter 274. The filter 276 is a low-pass filter that removes high-frequency components from the gate signal of the low-side transistor LH, which is the enable signal EN. The output of the filter 276 is a mask signal MSK that goes high when the power short detection circuit 260 is enabled. The AND gate 278 takes the logical AND of the output of the filter 274 and the mask signal MSK, and outputs the result as a power short detection signal SDET.

[0084] Next, a description will be given of the threshold voltage source 290. The threshold voltage source 290 includes a second current source 292, a fourth resistor R14, MOS transistors M11 to M13, and an amplifier 296.

[0085] The second current source 292 generates a reference current Ir. For example, the second current source 292 includes a reference current source 293 and a current mirror circuit CM11.

[0086] The fourth resistor R14 and the MOS transistors M11 to M13 are connected in series, and a series connection circuit 294 including them is provided on the path of the reference current Ir. The gates of the MOS transistors M11 to M13 are connected to a constant voltage V REG It is biased by a constant voltage V REG may be substantially the same voltage level as the gate high voltage of the low-side transistor ML. A voltage drop (reference voltage) Vr based on the reference current Ir occurs in the series connection circuit 294. The reference voltage Vr is expressed by equation (2). Vr = Vds + R14 × Ir … (2) Vds is the total drain-source voltage of the MOS transistors M11 to M13.

[0087] The fourth resistor R14 has the same polarity of temperature dependence as the third resistor R13. The third resistor R13 and the fourth resistor R14 preferably have the same element structure. For example, the third resistor R13 and the fourth resistor R14 may be polysilicon resistors with negative temperature characteristics.

[0088] Threshold voltage source 290 outputs a threshold voltage Vth according to a reference voltage Vr. In this example, threshold voltage source 290 includes an amplifier 296, which amplifies the voltage drop Vr and outputs the amplified voltage as threshold voltage Vth. Amplifier 296 is, for example, a non-inverting amplifier, and includes an operational amplifier OA31 and resistors R31 and R32. The threshold voltage Vth is expressed by equation (3). Vth=g×Vr=g×(Vds+R14×Ir) …(3) g is the gain of the amplifier 296, where g=(R31+R32) / R31.

[0089] There is no particular limitation on the method for switching the threshold voltage Vth between two values. For example, the gain (R32+R31) / R31 of the amplifier 296 may be switched between two values. In this case, at least one of the resistors R31 and R32 may be configured as a variable resistor whose resistance value can be switched.

[0090] Alternatively, the mirror ratio of the current mirror circuit CM11 may be made switchable, or the fourth resistor R14 may be configured as a variable resistor.

[0091] The above is the configuration of the power short detection circuit 260 and the threshold voltage source 290. Next, the operation of the power short detection circuit 260 will be described.

[0092] 9 is a circuit diagram illustrating power short detection by the power short detection circuit 260. The switching terminal SW is shorted (power shorted) to the power supply line 202 via the power short path 4, and a short current flows through the low-side transistor ML. At this time, in the power short detection circuit 260, a short current Ishort flows through the power short path 4, the first switch SW11, and the first resistor R11.

[0093] Since the sum of the short-circuit current Ishort and the current Ic generated by the first current source 262 flows through the first resistor R11, the voltage Ve of the emitter of the first transistor Q11 is expressed by equation (3). Ve=R11×(Ishort+Ic) …(3)

[0094] Since the base-emitter voltage of the first transistor Q11 and the base-emitter voltage of the second transistor Q12 are substantially equal, a voltage equal to the emitter voltage Ve of the first transistor Q11 is generated at the emitter of the second transistor Q12. At this time, a detection current Idet expressed by equation (4) flows through the second resistor R12. Idet=Ve / R12=R11×(Ishort+Ic) / R12…(4)

[0095] When R11=R12, Idet=(Ishort+Ic) …(4') This becomes:

[0096] This detection current Idet is reflected by the current mirror circuit 264, and the detection current Idet' is supplied to the third resistor R13. When the current amplification factor (mirror ratio) of the current mirror circuit 264 is γ, the detection current Idet' is expressed by equation (5). Idet' = Idet × γ …(5) The current amplification factor γ may be set to 1 or a value greater than 1.

[0097] The voltage drop that occurs across the third resistor R13 due to the flow of the current Idet' is the detection voltage VdetL, which is expressed by equation (6). VdetL=Idet'×R13=γ×(Ishort+Ic)×R13 …(6) That is, in this configuration, γ×R13 corresponds to the conversion gain β of the detection voltage generating circuit 261.

[0098] The threshold voltage Vth is set to be higher than the detection voltage VdetL when no short to power occurs (Ishort=0) and lower than the detection voltage VdetL when a short to power occurs (Ishort>0). When a short to power occurs and a large short current Ishort flows, VdetL>Vth, and the short to power detection signal SDET is asserted.

[0099] As described above, according to the semiconductor integrated circuit 200 according to the embodiment, the power short detection circuit 260 can detect a power short to the switching terminal SW.

[0100] The determination circuit 270 compares the detection voltage VdetL expressed by the equation (6) with the threshold voltage Vth expressed by the equation (3). VdetL=Idet'×R13=γ×(Ishort+Ic)×R13 …(6) Vth=g×Vr=g×(Vds+R14×Ir) …(3)

[0101] When the third resistor R13 has a negative temperature characteristic, the detection voltage VdetL also has a negative temperature characteristic. If the threshold voltage Vth has no temperature dependence or a positive temperature characteristic, the conditions for determining whether or not the power supply is shorted to the power source will vary greatly with temperature.

[0102] In contrast, in this embodiment, the fourth resistor R14 has the same polarity (negative) temperature characteristic as the third resistor R13. Therefore, the threshold voltage Vth expressed by equation (3) also has negative temperature dependence and follows the temperature fluctuation of the detection voltage VdetL. This reduces the temperature dependence of the determination condition for a power short state.

[0103] 8, the voltage level of the threshold voltage Vth and its temperature characteristics can be designed using the number of MOS transistors M11 to M13, the element size, the resistance value of the fourth resistor R14, and the gain g as parameters. Note that if the gain g=1, the amplifier 296 can be omitted.

[0104] Next, the ground fault detection circuit 240 will be described.

[0105] 10 is a circuit diagram of a ground fault detection circuit 240 according to an embodiment. The ground fault detection circuit 240 has a configuration in which the top and bottom (power supply line and ground line) of the ground fault detection circuit 260 are inverted and the P-type transistors and N-type transistors are interchanged.

[0106] The detection voltage generating circuit 241 includes a third switch SW21, a fourth switch SW22, a third current source 242, a fifth resistor R21, a sixth resistor R22, a seventh resistor R23, a third transistor Q21, a fourth transistor Q22, and a level shifter 246.

[0107] A first terminal of the fifth resistor R21 is connected to the power supply line 202. A first terminal of the sixth resistor R22 is connected to the power supply line 202.

[0108] The third switch SW21 is connected between the second end of the fifth resistor R21 and the output line 204. The third switch SW21 is turned on when the high-side transistor MH is on. For example, the third switch SW21 is an NMOS transistor, and the gate of the third switch SW21 is supplied with the gate signal of the high-side transistor MH.

[0109] The fourth switch SW22 is connected between the power supply line 202 and the second end of the fifth resistor R21, and is turned on when the high-side transistor MH is turned off.

[0110] When the third switch SW21 is on and the fourth switch SW22 is off, the ground fault detection circuit 240 is enabled. When the third switch SW21 is off and the fourth switch SW22 is on, the ground fault detection circuit 240 is disabled.

[0111] The third transistor Q21 is a PNP bipolar transistor, and has a first electrode (emitter) connected to the second end of the fifth resistor R21. A second electrode (collector) and a control electrode (base) of the third transistor Q21 are connected to the third current source 242. The third current source 242 includes, for example, a reference current source 243 and a current mirror circuit CM20, and sinks a constant current Ic.

[0112] The fourth transistor Q22 is a PNP bipolar transistor of the same type as the third transistor Q21, and has a first electrode (emitter) connected to the second end of the sixth resistor R22 and a control electrode (base) connected to the control electrode (base) of the third transistor Q21.

[0113] The seventh resistor R23 is provided on the path of a current Idet' that is proportional to the detection current Idet flowing through the fourth transistor Q22. A voltage drop proportional to the detection current Idet' occurs across the seventh resistor R23. VdetH=R23×Idet' The seventh resistor R23 may be provided on the path of the detection current Idet.

[0114] The determination circuit 250 generates a ground fault detection signal GDET based on the result of comparing the voltage drop (detection voltage) VdetH across the seventh resistor R23 with a predetermined threshold voltage Vth. Specifically, the determination circuit 250 asserts the ground fault detection signal GDET when VdetH>Vth. The threshold voltage Vth is generated by a threshold voltage source 290 having the configuration shown in FIG. 8.

[0115] In this embodiment, the determination circuit 250 includes a comparator 252, a filter 254, a filter 256, and an AND gate 258. The comparator 252 compares the detection voltage VdetH with a predetermined threshold voltage Vth. The filter 254 is a low-pass filter that removes high-frequency components from the output signal COMP of the comparator 252. The filter 254 removes noise components. The level shifter 246 level-shifts down the enable signal EN, which is the gate signal of the high-side transistor MH. The filter 256 is also a low-pass filter that removes high-frequency components from the output of the level shifter 246. The output of the level shifter 246 becomes a mask signal MSK that is at a high level when the ground fault detection circuit 240 is enabled. The AND gate 258 takes the logical AND of the output of the filter 254 and the mask signal MSK, and outputs the result as a ground fault detection signal GDET.

[0116] The above is the configuration of the ground fault detection circuit 240. According to this ground fault detection circuit 240, by operating in the same manner as the power fault detection circuit 260, it is possible to detect a ground fault at the output terminal SW.

[0117] As explained with respect to the power fault detection circuit 260, the ground fault detection circuit 240 can reduce the temperature dependency of the determination conditions for ground fault detection.

[0118] (Variation) Modifications of the power fault detection circuit 260 and the ground fault detection circuit 240 will be described.

[0119] Regarding the power short detection circuit 260, the first switch SW11 may be configured with a PMOS transistor, and the second switch SW12 may be omitted.

[0120] Regarding the ground fault detection circuit 240, the fourth switch SW22 may be configured with an NMOS transistor similar to the high-side transistor MH, or the fourth switch SW22 may be omitted.

[0121] 7, the method of changing the threshold current Ith is not limited to the method of changing the threshold voltage Vth. For example, the threshold current I THH ,I THL Specifically, in the detection voltage generation circuit 261 of Fig. 8, the conversion gain β can be made variable by making the mirror ratio γ of the current mirror circuit 264 variable or by configuring the resistor R13 as a variable resistor. The same applies to the ground fault detection circuit 240 of Fig. 10, and the resistance value of the seventh resistor R23 in the detection voltage generation circuit 241 may be made variable.

[0122] The configuration of the determination circuit 270 is not limited to that shown in Figure 8. Circuit elements other than a voltage comparator may be used for voltage comparison. For example, a MOS transistor may be used as the voltage comparison means. The same applies to the determination circuit 250.

[0123] In the embodiment, the semiconductor integrated circuit 200 is described as including both the power fault detection circuit 260 and the ground fault detection circuit 240, but only one of them may be provided.

[0124] 11 is a block diagram of an audio system 400. The audio system 400 includes an audio IC 200C, a speaker 402, a filter 404, and a bootstrap capacitor C BS , and a battery 410.

[0125] The audio IC 200C is a class-D amplifier and includes a high-side transistor MH, a low-side transistor ML, a high-side driver 210, a low-side driver 220, level shifters 230 and 232, a ground fault detection circuit 240, and a pulse width modulator 310. The high-side transistor MH is connected between a power supply pin VCC and a switching pin SW, and the low-side transistor ML is connected between the switching pin SW and a ground pin GND.

[0126] The pulse width modulator 310 converts the audio signal V AUD is converted into a PWM (pulse width modulation) signal to generate the control signals HIN and LIN.

[0127] The control signal HIN is level-shifted up by the level shifter 230 and supplied to the high-side driver 210 .

[0128] The level shifter 232 is provided as a dummy to equalize the delay amounts on the high side and the low side. The level shifter 232 may be omitted. The low-side driver 220 drives the low-side transistor ML in accordance with the output of the level shifter 232.

[0129] 12 is a block diagram of a buck converter 500. The buck converter 500 includes a controller IC 200D and a buck converter main circuit 510. The buck converter 500 converts a power supply voltage V CC output voltage V OUT and supplies the voltage to a load (not shown) connected to the output line 504. The main circuit 510 includes a high-side transistor MH, a low-side transistor ML, an inductor L2, and an output capacitor C2.

[0130] The controller IC 200D includes a high-side transistor MH, a low-side transistor ML, a high-side driver 210, a low-side driver 220, a level shifter 230, a ground fault detection circuit 240, and a feedback circuit 320. Resistors R21 and R22 are connected to each other to provide a voltage difference between the output voltage V OUTis divided, and the feedback voltage after division is V FB is supplied to the feedback pin FB of the controller IC200D.

[0131] The feedback circuit 320 generates a feedback voltage V FB is the predetermined reference voltage V REF The feedback circuit 320 generates a PWM signal whose duty cycle is adjusted so that the duty cycle approaches . The feedback circuit 320 generates control signals HIN and LIN in response to the PWM signal. The level shifter 230 level-shifts the control signal HIN and supplies it to the high-side driver 210. The control signal LIN is also supplied directly to the low-side driver 220. A dummy level shifter may be inserted between the feedback circuit 320 and the low-side driver 220.

[0132] The step-down converter 500 may be of a diode rectification type, in which case a rectification diode is connected instead of the low-side transistor ML, and the low-side driver 220 is omitted.

[0133] (Addendum) The present specification discloses the following techniques.

[0134] (Item 1) a power supply line, an output line, and a ground line; an output stage including a high-side transistor connected between the power supply line and an output line and a low-side transistor connected between the output line and the ground line; a short-circuit detection circuit that determines a short-circuit state when one of the low-side transistor and the high-side transistor to be monitored is enabled during an on-period and a current flowing through the transistor to be monitored exceeds a threshold current; Equipped with The threshold current periodically repeats a variation in which it takes a relatively large first value for a relatively long first period and a relatively small second value for a relatively short second period.

[0135] (Item 2) 2. The semiconductor integrated circuit according to item 1, wherein the length of the second period is 1Ts to 10Ts, where Ts is a switching period of the output stage.

[0136] (Item 3) 3. The semiconductor integrated circuit according to item 1 or 2, wherein the sum of the first period and the second period is 0.5 ms to 1 ms.

[0137] (Item 4) The short circuit detection circuit a detection voltage generating circuit that converts a current flowing through the transistor to be monitored into a detection voltage; a determination circuit that compares the detection voltage with a threshold voltage that defines the threshold current, and generates a short detection signal when the detection voltage exceeds the threshold voltage; 4. The semiconductor integrated circuit according to any one of items 1 to 3, comprising:

[0138] (Item 5) 5. The semiconductor integrated circuit according to item 4, further comprising a threshold voltage source that generates a threshold voltage that assumes a first voltage level in the first period and a second voltage level in the second period.

[0139] (Item 6) 6. The semiconductor integrated circuit according to item 4 or 5, wherein the transistor to be monitored is a high-side transistor, and the short-circuit detection circuit performs ground fault detection.

[0140] (Item 7) The detection voltage generation circuit a first resistor having a first end connected to the ground line; a second resistor having a first end connected to the ground line; a first switch connected between the second end of the first resistor and the output line, the first switch being turned on when the low-side transistor is on; a first current source; a first N-type transistor having a first electrode connected to the second end of the first resistor, and having a control electrode and a second electrode connected to the first current source; a second N-type transistor having a first electrode connected to the second end of the second resistor and a control electrode connected to the control electrode of the first transistor; a third resistor provided on a path of a detection current proportional to the current flowing through the second transistor; 7. The semiconductor integrated circuit according to item 6, wherein the voltage drop across the third resistor is the detection voltage.

[0141] (Item 8) 8. The semiconductor integrated circuit according to item 7, wherein the detection voltage generation circuit further includes a second switch connected between the second end of the first resistor and the ground line and turned on when the low-side transistor is off.

[0142] (Item 9) 6. The semiconductor integrated circuit according to item 4 or 5, wherein the transistor to be monitored is a low-side transistor, and the short detection circuit performs short-to-power detection.

[0143] (Item 10) The detection voltage generation circuit a fifth resistor having a first end connected to the power supply line; a sixth resistor having a first end connected to the power supply line; a third switch connected between the second end of the fifth resistor and the output line, the third switch being turned on when the high-side transistor is on; a third current source; a third transistor of P type having a first electrode connected to the second end of the fifth resistor and having a control electrode and a second electrode connected to the third current source; a fourth transistor of P-type having a first electrode connected to the second end of the sixth resistor and a control electrode connected to the control electrode of the third transistor; a seventh resistor provided on a path of a detection current proportional to the current flowing through the fourth transistor; 10. The semiconductor integrated circuit according to item 9, comprising: a seventh resistor; and a voltage drop across the seventh resistor is the detection voltage.

[0144] (Item 11) Item 11. The semiconductor integrated circuit according to item 10, wherein the detection voltage generation circuit further includes a fourth switch connected between the second end of the fifth resistor and the power supply line and turned on when the high-side transistor is off.

[0145] (Item 12) The threshold voltage source is a reference voltage source that generates a reference voltage; a variable gain amplifier that amplifies the reference voltage with a gain that is a first value during the first period and a second value during the second period; 6. The semiconductor integrated circuit according to item 5, comprising:

[0146] (Item 13) The threshold voltage source is a reference voltage source that generates a reference voltage that has a first level during the first period and a second level during the second period; an amplifier that amplifies the reference voltage; 6. The semiconductor integrated circuit according to item 5, comprising:

[0147] (Item 14) The reference voltage source is a second current source that generates a reference current; a series-connected circuit including a fourth resistor connected in series on a path of the reference current and a MOS (Metal Oxide Semiconductor) transistor whose gate is biased with a constant voltage; Item 14. The semiconductor integrated circuit according to item 12 or 13, comprising: a first input terminal for inputting a voltage drop across the series-connected circuit; and a second input terminal for outputting a threshold voltage corresponding to the voltage drop across the series-connected circuit.

[0148] (Item 15) 15. The semiconductor integrated circuit according to any one of items 1 to 14, which is an audio class D amplifier.

[0149] (Item 16) 15. The semiconductor integrated circuit according to any one of items 1 to 14, which is a switching regulator.

[0150] (Item 17) 15. The semiconductor integrated circuit according to any one of items 1 to 14, which is for use in a vehicle.

[0151] Although the embodiments of the present disclosure have been described using specific terms, this description is merely an example to facilitate understanding and does not limit the scope of the present disclosure or the claims. The scope of the present invention is defined by the claims, and therefore, embodiments, examples, and modifications not described herein are also included in the scope of the present invention. [Explanation of symbols]

[0152] 200 Semiconductor Integrated Circuits 210 High Side Driver 220 Low Side Driver 230,232 Level Shifter MH high-side transistor ML low-side transistor VCC power supply pin SW Switching terminal GND Grounding terminal BS Bootstrap terminal 202 Power Line 203 Constant voltage line 204 output lines 206 Ground Line 208 Bootstrap Line 209 Rectifying element 240 Ground fault detection circuit SW21 3rd switch SW22 4th switch R21 5th resistor R22 6th resistor R23 7th resistor Q21 Third transistor Q22 4th transistor 241 Detection voltage generation circuit 242 Third current source 243 Reference current source 246 Level Shifter 250 Judgment circuit 252 Comparator 254,256 filters 258 AND Gate 260 Power supply short detection circuit 261 Detection voltage generation circuit SW11 First switch SW12 Second switch R11 1st resistor R12 Second resistor R13 Third resistor Q11 First transistor Q12 Second transistor 262 1st current source 263 Reference current source 264 Current Mirror Circuit 265 Output Nodes 270 Judgment circuit 272 Comparator 274,276 filters 278 AND Gate 290 Threshold Voltage Source 291 Controller Circuit 292 2nd current source 293 Reference current source CM11 current mirror circuit R14 4th Resistor M11, M12, M13 MOS transistors 294 Series Connection Circuit 296 Amplifier OA31 operational amplifier R31,R32 resistance 200C Audio IC 200D Controller IC 310 Pulse Width Modulator 320 Feedback Circuit 400 Audio System 402 Speaker 404 filter 410 Battery 500 Buck Converter 502 input lines 504 output line 510 Main circuit

Claims

1. a power supply line, an output line, and a ground line; an output stage including a high-side transistor connected between the power supply line and an output line and a low-side transistor connected between the output line and the ground line; a short-circuit detection circuit that determines a short-circuit state when one of the low-side transistor and the high-side transistor to be monitored is enabled during an on-period and a current flowing through the transistor to be monitored exceeds a threshold current; Equipped with The threshold current periodically repeats a variation in which it takes a relatively large first value for a relatively long first period and a relatively small second value for a relatively short second period.

2. 2. The semiconductor integrated circuit according to claim 1, wherein the length of said second period is 1Ts to 10Ts, where Ts is a switching period of said output stage.

3. 2. The semiconductor integrated circuit according to claim 1, wherein the sum of the first period and the second period is 0.5 ms to 1 ms.

4. The short circuit detection circuit a detection voltage generating circuit that converts a current flowing through the transistor to be monitored into a detection voltage; a determination circuit that compares the detection voltage with a threshold voltage that defines the threshold current, and generates a short detection signal when the detection voltage exceeds the threshold voltage; 4. The semiconductor integrated circuit according to claim 1, comprising:

5. 5. The semiconductor integrated circuit according to claim 4, further comprising a threshold voltage source that generates a threshold voltage that takes a first voltage level in said first period and a second voltage level in said second period.

6. 5. The semiconductor integrated circuit according to claim 4, wherein the transistor to be monitored is a high-side transistor, and the short-circuit detection circuit detects a ground fault.

7. The detection voltage generation circuit a first resistor having a first end connected to the ground line; a second resistor having a first end connected to the ground line; a first switch connected between the second end of the first resistor and the output line, the first switch being turned on when the low-side transistor is on; a first current source; a first N-type transistor having a first electrode connected to the second end of the first resistor, and having a control electrode and a second electrode connected to the first current source; a second N-type transistor having a first electrode connected to the second end of the second resistor and a control electrode connected to the control electrode of the first transistor; a third resistor provided on a path of a detection current proportional to the current flowing through the second transistor; 7. The semiconductor integrated circuit according to claim 6, wherein a voltage drop across the third resistor is the detection voltage.

8. 8. The semiconductor integrated circuit according to claim 7, wherein the detection voltage generation circuit further includes a second switch connected between the second end of the first resistor and the ground line, the second switch being turned on when the low-side transistor is off.

9. 5. The semiconductor integrated circuit according to claim 4, wherein the transistor to be monitored is a low-side transistor, and the short detection circuit performs short-to-power detection.

10. The detection voltage generation circuit a fifth resistor having a first end connected to the power supply line; a sixth resistor having a first end connected to the power supply line; a third switch connected between the second end of the fifth resistor and the output line, the third switch being turned on when the high-side transistor is on; a third current source; a third P-type transistor having a first electrode connected to the second end of the fifth resistor, and having a control electrode and a second electrode connected to the third current source; a fourth transistor of P-type having a first electrode connected to the second end of the sixth resistor and a control electrode connected to the control electrode of the third transistor; a seventh resistor provided on a path of a detection current proportional to the current flowing through the fourth transistor; 10. The semiconductor integrated circuit according to claim 9, comprising: a seventh resistor; and a voltage drop across the seventh resistor is the detection voltage.

11. 11. The semiconductor integrated circuit according to claim 10, wherein the detection voltage generation circuit further includes a fourth switch connected between the second end of the fifth resistor and the power supply line, the fourth switch being turned on when the high-side transistor is off.

12. The threshold voltage source is a reference voltage source that generates a reference voltage; a variable gain amplifier that amplifies the reference voltage with a gain that is a first value during the first period and a second value during the second period; 6. The semiconductor integrated circuit according to claim 5, comprising:

13. The threshold voltage source is a reference voltage source that generates a reference voltage that has a first level during the first period and a second level during the second period; an amplifier that amplifies the reference voltage; 6. The semiconductor integrated circuit according to claim 5, comprising:

14. The reference voltage source is a second current source that generates a reference current; a series-connected circuit including a fourth resistor connected in series on a path of the reference current and a MOS (Metal Oxide Semiconductor) transistor whose gate is biased with a constant voltage; 13. The semiconductor integrated circuit according to claim 12, further comprising: a first input terminal for inputting a voltage drop across said series-connected circuit;

15. 4. The semiconductor integrated circuit according to claim 1, which is an audio class D amplifier.

16. 4. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is a switching regulator.

17. 4. The semiconductor integrated circuit according to claim 1, which is for use in a vehicle.

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