Semiconductor integrated circuit

Abstract

To provide a semiconductor integrated circuit including a short-circuit detection circuit capable of detecting a ground fault and a power short.SOLUTION: A first switch SW1 is connected between a first resistor R1 and an output line 204, and is turned on when a low-side transistor is on. A second switch SW2 is connected between a third resistor R3 and the output line 204, and is turned on when a high-side transistor MH is on. A current adding circuit 250 adds a current Idet1 flowing through a second transistor Q2 and a current Idet2 flowing through a fourth transistor Q4, and supplies the added current to a fifth resistor R5. A determination circuit 260 detects a power short or a ground fault on the basis of a detection signal Vdet, which is a voltage drop across the fifth resistor R5.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 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 is sometimes provided in semiconductor integrated circuits. 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 is sometimes provided in semiconductor integrated circuits. [Prior art documents] [Patent documents]

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

[0005] [overview] Providing separate ground fault detection circuits and power fault detection circuits increases the circuit area, and there is also the possibility that the threshold values for the ground fault detection circuit and power fault detection circuit may differ.

[0006] The present disclosure has been made in light of the above-mentioned circumstances, and it is an exemplary purpose of an embodiment of the present disclosure to provide a semiconductor integrated circuit including a short-circuit detection circuit capable of detecting a short to power and a short to ground.

[0007] 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 for detecting a short to power and a short to ground of the output line. The short-circuit detection circuit includes 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 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, a third resistor having a first end connected to the power supply line, a fourth resistor having a first end connected to the power supply line, and a second N-type transistor having a first end connected to the power supply line and a second N-type transistor having a control electrode connected to the control electrode of the first transistor. the P-type fourth transistor having a first electrode connected to the second end of the fourth resistor and a control electrode connected to the control electrode of the third transistor; a current adder circuit that adds a first detection current flowing in the second transistor and a second detection current flowing in the fourth transistor; a fifth resistor provided on a path of the output current of the current adder circuit; and a determination circuit that generates a short detection signal based on a result of comparing a voltage drop across the fifth resistor with a threshold voltage. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram of a semiconductor integrated circuit according to an embodiment. [Figure 2] FIG. 2 is a circuit diagram of the short detection circuit according to the embodiment. [Figure 3] FIG. 3 is a circuit diagram illustrating power supply short detection by the short detection circuit. [Figure 4]FIG. 4 is a circuit diagram illustrating the ground fault detection of the short circuit detection circuit. [Figure 5] FIG. 5 is a circuit diagram showing an example of the configuration of the determination circuit. [Figure 6] FIG. 6 is a block diagram of an audio system. [Figure 7] FIG. 7 is a block diagram of a step-down converter.

[0009] [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.

[0010] 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 for detecting a short to power and a short to ground of the output line. The short-circuit detection circuit includes 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 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, a third resistor having a first end connected to the power supply line, a fourth resistor having a first end connected to the power supply line, and a second N-type transistor having a first end connected to the power supply line and a second N-type transistor having a control electrode connected to the control electrode of the first transistor. the P-type fourth transistor having a first electrode connected to the second end of the fourth resistor and a control electrode connected to the control electrode of the third transistor; a current adder circuit that adds a first detection current flowing in the second transistor and a second detection current flowing in the fourth transistor; a fifth resistor provided on a path of the output current of the current adder circuit; and a determination circuit that generates a short detection signal based on a result of comparing a voltage drop across the fifth resistor with a threshold voltage.

[0011] With this configuration, the fifth resistor and the determination circuit are common to both power fault detection and ground fault detection, which reduces the circuit area. Furthermore, because the fifth resistor and the determination circuit are common, the determination thresholds for both power fault detection and ground fault detection can be made uniform.

[0012] In one embodiment, the short detection circuit may further include a third switch connected between the second end of the first resistor and the ground line, and turned on when the high-side transistor is on.

[0013] In one embodiment, the short detection circuit may further include a fourth switch connected between the second end of the third resistor and the power supply line, and turned on when the high-side transistor is on.

[0014] In one embodiment, the determination circuit may include a comparator that compares the voltage drop across the fifth resistor with a threshold voltage and generates a short detection signal.

[0015] In one embodiment, the determination circuit may further include a first logic gate that performs a logical operation on a logic signal based on the output of the comparator and a control signal that is high when the high-side transistor is on, and a second logic gate that performs a logical operation on a logic signal based on the output of the comparator and a control signal that is high when the low-side transistor is on, thereby making it possible to distinguish between a power short and a ground short and to handle the occurrence of such a short.

[0016] In one embodiment, the semiconductor integrated circuit may be an audio class D amplifier.

[0017] In one embodiment, the semiconductor integrated circuit may be a switching regulator.

[0018] In one embodiment, the semiconductor integrated circuit may be for use in a vehicle.

[0019] (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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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 is connected.

[0024] The semiconductor integrated circuit 200 supplies a high-level voltage V CC , a low level voltage of 0V, or a high impedance state.

[0025] 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, and a short-circuit detection circuit 240.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 V CC 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.

[0030] The short detection circuit 240 enters a short-to-power detection mode in a low output state where the high-side transistor MH is off and the low-side transistor ML is on. In the short-to-power detection mode, the short detection circuit 240 can detect a short-to-power abnormality in the switching terminal SW, and when a short-to-power abnormality is detected, the short detection circuit 240 asserts the short detection signal SDET (for example, to a high level).

[0031] The short-circuit detection circuit 240 is in a ground fault detection mode in a high output state in which the high-side transistor MH is on and the low-side transistor ML is off. In the ground fault detection mode, the short-circuit detection circuit 240 can detect a ground fault abnormality in the switching terminal GND, and when a ground fault abnormality is detected, the short-circuit detection circuit 240 asserts the short-circuit detection signal SDET (for example, to a high level).

[0032] 2 is a circuit diagram of a short detection circuit 240 according to an embodiment. The short detection circuit 240 includes a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a first current source 242, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a current adder circuit 250, and a determination circuit 260.

[0033] A first end of the first resistor R1 is connected to the ground line 206. A first end of the second resistor R2 is connected to the ground line 206.

[0034] The first switch SW1 is connected between the second end of the first resistor R1 and the output line 204. The first switch SW1 is turned on when the low-side transistor ML is on. For example, the first switch SW1 is an NMOS transistor, and the gate of the first switch SW1 is supplied with the gate signal of the low-side transistor ML.

[0035] The third switch SW3 is connected between the ground line 206 and the second end of the first resistor R1, and is turned on when the low-side transistor ML is off. For example, the third switch SW3 is an NMOS transistor, and a signal obtained by inverting the gate signal of the low-side transistor ML by an inverter 222 is supplied to the gate of the third switch SW3.

[0036] When the first switch SW1 is on and the third switch SW3 is off, the short detection circuit 240 is in a short-to-power detection mode.

[0037] The first transistor Q1 is an NPN bipolar transistor, and a first electrode (emitter) is connected to the second end of the first resistor R1. A second electrode (collector) and a control electrode (base) of the first transistor Q1 are connected to a first current source 242. The first current source 242 includes, for example, a first current source CS1 and a current mirror circuit CM1, and sources a constant current Ic. The first current mirror circuit CM1 is connected to a constant voltage line 203. The constant voltage line 203 is connected to a power supply voltage V CCLower constant voltage V REGD is being supplied.

[0038] The second transistor Q2 is an NPN bipolar transistor of the same type as the first transistor Q1, and has a first electrode (emitter) connected to the second end of the second resistor R2 and a control electrode (base) connected to the control electrode (base) of the first transistor Q1.

[0039] The first detection current Idet1 flowing through the second transistor Q2 is supplied to the current adder circuit 250. The current adder circuit 250 is connected to the constant voltage line 203.

[0040] The second switch SW2 is connected between the second end of the third resistor R3 and the output line 204. The second switch SW2 is turned on when the high-side transistor MH is on. For example, the second switch SW2 is an NMOS transistor, and the gate of the second switch SW2 is supplied with the gate signal of the high-side transistor MH.

[0041] The fourth switch SW4 is connected between the power supply line 202 and the second end of the third resistor R3, and is turned on when the high-side transistor MH is off. For example, the fourth switch SW4 is a PMOS transistor, and the gate of the fourth switch SW4 is supplied with the gate signal of the high-side transistor MH.

[0042] When the second switch SW2 is on and the fourth switch SW4 is off, the short detection circuit 240 is in a ground fault detection mode.

[0043] The third transistor Q3 is a PNP bipolar transistor, and has a first electrode (emitter) connected to the second end of the third resistor R3. A second electrode (collector) and a control electrode (base) of the third transistor Q3 are connected to the second current source 246. The second current source 246 includes, for example, a second current source CS2 and a current mirror circuit CM2, and sinks a constant current Ic.

[0044] The fourth transistor Q4 is a PNP bipolar transistor of the same type as the third transistor Q3, and has a first electrode (emitter) connected to the second end of the fourth resistor R4 and a control electrode (base) connected to the control electrode (base) of the third transistor Q3. The second detection current Idet2 flowing through the fourth transistor Q4 is supplied to the current adder circuit 250.

[0045] The current adder circuit 250 adds the first detection current Idet1 and the second detection current Idet2. For example, the current adder circuit 250 includes current mirror circuits CM3 to CM5. The current mirror circuit CM3 reflects the first detection current Idet1. The current mirror circuits CM4 and CM5 reflect the second detection current Idet2. The two reflected detection currents Idet1' and Idet2' join at an output node 252, and a total current Idet=Idet1'+Idet2' is supplied to the fifth resistor R5.

[0046] The fifth resistor R5 is connected between the output node 252 of the current adder circuit 250 and the ground line 206. A voltage drop proportional to the output current Idet of the current adder circuit 250 occurs across the fifth resistor R5. Vdet=R5×Idet' …(1)

[0047] The determination circuit 260 generates a short detection signal SDET based on the result of comparing a voltage drop (detection voltage) Vdet across the fifth resistor R5 with a predetermined threshold voltage Vth. Specifically, the determination circuit 260 asserts the short detection signal SDET when Vdet>Vth.

[0048] The above is the configuration of the short circuit detection circuit 240. Next, the operation of the short circuit detection circuit 240 in the power fault detection mode and the ground fault detection mode will be described.

[0049] 3 is a circuit diagram illustrating power short detection by the short detection circuit 240. The switching terminal SW is shorted (shorted to power) to the power supply line 202 via the power short path 2, and a short current flows through the low-side transistor ML. At this time, in the short detection circuit 240, a short current Ishort flows through the power short path 2, the first switch SW1, and the first resistor R1.

[0050] Since the sum of the short-circuit current Ishort and the current Ic generated by the first current source 242 flows through the first resistor R1, the voltage Ve of the emitter of the first transistor Q1 is expressed by equation (2). Ve=R1×(Ishort+Ic) …(2)

[0051] Since the base-emitter voltage of the first transistor Q1 and the base-emitter voltage of the second transistor Q2 are substantially equal, a voltage equal to the emitter voltage Ve of the first transistor Q1 is generated at the emitter of the second transistor Q2. At this time, a first detection current Idet1 expressed by equation (3) flows through the second resistor R2. Idet1=Ve / R2=R1×(Ishort+Ic) / R2 …(3)

[0052] When R1=R2, Idet1=(Ishort+Ic) …(3') This becomes:

[0053] In the short-to-power detection mode, the second detection current Idet2 flowing through the fourth transistor Q4 is very small, so that the current adder circuit 250 outputs a detection current Idet that is substantially equal to the first detection current Idet1′ and supplies it to the fifth resistor R5.

[0054] The voltage drop that occurs in the fifth resistor R5 due to the current Idet' flowing is the detection voltage Vdet, which is expressed by equation (4): α3 is the current amplification factor (mirror ratio) of the current mirror circuit CM3. Vdet=Idet'×R5=α3×(Ishort+Ic)×R5 …(4)

[0055] The threshold voltage Vth is set to be higher than the detection voltage Vdet when no short to power occurs (Ishort=0) and lower than the detection voltage Vdet when a short to power occurs (Ishort>0). When a short to power occurs and a large short current Ishort flows, Vdet>Vth, and the short detection signal SDET is asserted.

[0056] As described above, according to the semiconductor integrated circuit 200 according to the embodiment, the short circuit detection circuit 240 can detect a short circuit to the power supply at the switching terminal SW.

[0057] 4 is a circuit diagram illustrating ground fault detection by the short detection circuit 240. The switching terminal SW is shorted (ground faulted) to the ground line 206 via the ground fault path 4, and a short current flows through the high-side transistor MH. At this time, in the short detection circuit 240, the short current Ishort flows through the ground fault path 4, the second switch SW2, and the third resistor R3.

[0058] Since the sum of the short-circuit current Ishort and the current Ic generated by the second current source 246 flows through the third resistor R3, the voltage Ve of the emitter of the third transistor Q3 is expressed by equation (5). Ve=V CC -R3×(Ishort+Ic) …(5)

[0059] Since the base-emitter voltage of the third transistor Q3 and the base-emitter voltage of the fourth transistor Q4 are substantially equal, a voltage equal to the emitter voltage Ve of the third transistor Q3 is generated at the emitter of the fourth transistor Q4. At this time, a second detection current Idet2 expressed by equation (6) flows through the fourth resistor R4. Idet2=(V CC -Ve) / R4=R3×(Ishort+Ic) / R4 …(6)

[0060] When R3=R4, Idet2=(Ishort+Ic) …(6') This becomes:

[0061] In the ground fault detection mode, the first detection current Idet1 flowing through the second transistor Q2 is very small, so that the current adder circuit 250 outputs a detection current Idet that is substantially equal to the second detection current Idet2′ and supplies it to the fifth resistor R5.

[0062] The voltage drop that occurs in the fifth resistor R5 due to the flow of the current Idet' is the detection voltage Vdet, which is expressed by equation (7): α4 is the product of the current amplification factors (mirror ratios) of the current mirror circuits CM4 and CM5. Vdet=Idet'×R5=α4×(Ishort+Ic)×R5 …(4)

[0063] The threshold voltage Vth is set to be higher than the detection voltage Vdet when no ground fault occurs (Ishort=0) and lower than the detection voltage Vdet when a ground fault occurs (Ishort>0). When a ground fault occurs and a large short-circuit current Ishort flows, Vdet>Vth, and the short detection signal SDET is asserted.

[0064] As described above, according to the semiconductor integrated circuit 200 according to the embodiment, the short detection circuit 240 can detect a ground fault at the switching terminal SW.

[0065] In the short circuit detection circuit 240, the fifth resistor R5 and the determination circuit 260 are shared between power short detection and ground short detection, so that an increase in the circuit area can be suppressed.

[0066] If the fifth resistor R5 and the determination circuit 260 are provided separately for power short detection and ground short detection, the resistance values of the fifth resistor R5 for power short detection and the fifth resistor R5 for ground short detection will vary, resulting in different determination criteria for power short detection and ground short detection. Furthermore, if the threshold value Vth of the determination circuit 260 for power short detection and the threshold value Vth of the determination circuit 260 for ground short detection vary, the determination criteria for power short detection and ground short detection will also vary. In this embodiment, the fifth resistor R5 and the determination circuit 260 are shared between power short detection and ground short detection, so the determination criteria for power short detection and ground short detection can be made uniform.

[0067] 5 is a circuit diagram showing an example configuration of the determination circuit 260. The determination circuit 260 includes a comparator 262, filters 263, 264, and 265, a level shifter 266, and logic gates 272 and 274. The comparator 262 compares the detection voltage Vdet with a predetermined threshold voltage Vth. The filter 263 is a low-pass filter that removes high-frequency components (noise components) from the output signal DET of the comparator 262.

[0068] The OR gate 270 takes the logical sum of the ground fault detection signal GDET and the power fault detection signal PDET and outputs the short circuit detection signal SDET. The determination circuit 260 may output the ground fault detection signal GDET and the power fault detection signal PDET separately as the short circuit detection signal SDET.

[0069] A level shifter 266 level-shifts down the gate signal HG of the high-side transistor MH. A filter 265 is a low-pass filter that removes high-frequency components from the gate signal of the high-side transistor MH after level shifting. The output of the filter 265 is asserted (high) in the ground fault detection mode. A logic gate 272 performs a logical AND between the output of the filter 265 and the output of the filter 263, and outputs the result as a ground fault detection signal GDET.

[0070] The filter 264 is a low-pass filter that removes high-frequency components from the gate signal of the low-side transistor ML. The output of the filter 264 is asserted (high) in the short-to-power detection mode. The logic gate 274 performs a logical AND between the output of the filter 264 and the output of the filter 263, and outputs the logical AND as the short-to-power detection signal PDET.

[0071] A description will now be given of a modified example of the short detection circuit 240. In the short detection circuit 240, the first switch SW1 may be configured with a PMOS transistor, and the third switch SW3 may be omitted.

[0072] Regarding the short detection circuit 240, the fourth switch SW4 may be configured with an NMOS transistor similar to the high-side transistor MH, or the fourth switch SW4 may be omitted.

[0073] The configuration of the determination circuit 260 is not limited to that shown in Figure 5. Circuit elements other than a voltage comparator may be used for voltage comparison. For example, a MOS transistor may be used as voltage comparison means. The same applies to the determination circuit 260. Also, the filters 263, 264, and 265 may be omitted.

[0074] The logic gates 272 and 274 are not limited to AND gates, and may be OR gates, NOR gates, or NAND gates. In such cases, the logical value (high / low) of the input signal may be appropriately inverted. If there is no need to distinguish between a power fault and a ground fault, the logic gates 272 and 274 may be omitted.

[0075] Next, the use of the switching circuit will be described.

[0076] 6 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.

[0077] 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 short-circuit detection circuit 240, and a pulse width modulator 310. The high-side transistor MH is connected between the input pin VIN and the switching pin SW, and the low-side transistor ML is connected between the switching pin SW and the ground pin GND.

[0078] 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.

[0079] The control signal HIN is level-shifted up by the level shifter 230 and supplied to the high-side driver 210 .

[0080] 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.

[0081] 7 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 , the 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.

[0082] 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 short-circuit detection circuit 240, and a feedback circuit 320. Resistors R21 and R22 are connected to each other toOUT is divided, and the feedback voltage after division is V FB is supplied to the feedback pin FB of the controller IC200D.

[0083] 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.

[0084] 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.

[0085] (Addendum) The present specification discloses the following techniques.

[0086] (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 for detecting a power short and a ground short of the output line; Equipped with The short circuit detection 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 having a first end connected to the power supply line; a fourth resistor having a first end connected to the power supply line; a second switch connected between the second end of the third resistor and the output line, the second switch being turned on when the high-side transistor is on; a second current source; a third transistor of P type having a first electrode connected to the second end of the third resistor and having a control electrode and a second electrode connected to the second current source; a fourth transistor of P type having a first electrode connected to the second end of the fourth resistor and a control electrode connected to the control electrode of the third transistor; a current adding circuit that adds a first detection current flowing through the second transistor and a second detection current flowing through the fourth transistor; a fifth resistor provided on a path of the output current of the current adder circuit; a determination circuit that generates a short detection signal based on a result of comparing the voltage drop across the fifth resistor with a threshold voltage; A semiconductor integrated circuit comprising:

[0087] (Item 2) Item 1. The semiconductor integrated circuit according to item 1, wherein the short detection circuit further includes a third switch connected between the second end of the first resistor and the ground line and turned on when the high-side transistor is on.

[0088] (Item 3) 3. The semiconductor integrated circuit according to claim 1, wherein the short detection circuit further includes a fourth switch connected between the second end of the third resistor and the power supply line and turned on when the high-side transistor is on.

[0089] (Item 4) 4. The semiconductor integrated circuit according to any one of items 1 to 3, wherein the determination circuit includes a comparator that compares a voltage drop across the fifth resistor with a threshold voltage and generates the short detection signal.

[0090] (Item 5) The determination circuit a first logic gate that performs a logic operation on a logic signal based on the output of the comparator and a control signal that is high when the high-side transistor is on; a second logic gate that performs a logic operation on a logic signal based on the output of the comparator and a control signal that is high when the low-side transistor is on; 5. The semiconductor integrated circuit according to item 4, further comprising:

[0091] (Item 6) 6. The semiconductor integrated circuit according to any one of items 1 to 5, which is an audio class D amplifier.

[0092] (Item 7) 6. The semiconductor integrated circuit according to any one of items 1 to 5, which is a switching regulator.

[0093] (Item 8) 8. The semiconductor integrated circuit according to any one of items 1 to 7, which is for use in a vehicle.

[0094] 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]

[0095] 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 Short circuit detection circuit SW1 First switch SW2 Second switch SW3 Third switch SW4 4th switch R1 First resistor R2 2nd resistor R3 3rd resistor R4 4th resistor R5 5th resistor Q1 First transistor Q2 Second transistor Q3 Third transistor Q4 Fourth transistor 242 1st current source 246 2nd current source 250 Current Adder Circuit 252 output nodes 262 Comparator 263,264,265 filters 266 Level Shifter 270 OR gate 272,274 AND gate 260 Judgment circuit 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 for detecting a power short and a ground short of the output line; Equipped with The short circuit detection 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 having a first end connected to the power supply line; a fourth resistor having a first end connected to the power supply line; a second switch connected between the second end of the third resistor and the output line, the second switch being turned on when the high-side transistor is on; a second current source; a third transistor of P-type having a first electrode connected to the second end of the third resistor, and having a control electrode and a second electrode connected to the second current source; a fourth P-type transistor having a first electrode connected to the second end of the fourth resistor and a control electrode connected to the control electrode of the third transistor; a current summing circuit that sums a first detection current flowing through the second transistor and a second detection current flowing through the fourth transistor; a fifth resistor provided on a path of the output current of the current adder circuit; a determination circuit that generates a short detection signal based on a result of comparing a voltage drop across the fifth resistor with a threshold voltage; A semiconductor integrated circuit comprising:

2. 2. The semiconductor integrated circuit according to claim 1, wherein the short detection circuit further comprises a third switch connected between the second end of the first resistor and the ground line and turned on when the high-side transistor is on.

3. 3. The semiconductor integrated circuit according to claim 1, wherein the short detection circuit further comprises a fourth switch connected between the second end of the third resistor and the power supply line and turned on when the high-side transistor is on.

4. 3. The semiconductor integrated circuit according to claim 1, wherein the determination circuit includes a comparator that compares a voltage drop across the fifth resistor with a threshold voltage and generates the short detection signal.

5. The determination circuit a first logic gate that performs a logic operation on a logic signal based on the output of the comparator and a control signal that is high when the high-side transistor is on; a second logic gate that performs a logic operation on a logic signal based on the output of the comparator and a control signal that is high when the low-side transistor is on; The semiconductor integrated circuit according to claim 4 , further comprising:

6. 3. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is an audio class D amplifier.

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

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

Images