Control devices for semiconductor devices and power supply devices

Abstract

Suppresses voltage detection errors. [Solution] The semiconductor device includes a Resurf MOSFET, a first transistor to a third transistor, and a detection circuit. The drain of the MOSFET is connected to the first terminal, the gate is connected to the first terminal via a pull-up resistor, and the source is connected to the second terminal which is connected to one end of a capacitor. One end of the spiral resistor is connected to the first terminal. The drain and gate of the first transistor are connected to the other end of the spiral resistor, and the source is connected to the third terminal. The gate of the second transistor is connected to the gate of the first transistor, the source is connected to the third terminal, and the drain is connected to the first node. The drain and gate of the third transistor are connected to the first node, and the source is connected to the second node. The detection circuit outputs a detection signal based on the current flowing through the third transistor.

Description

Technical Field

[0001] This disclosure relates to a control device for a semiconductor device and a power supply device.

Background Art

[0002] Patent Document 1 describes a control IC for a switching power supply in which a spiral high-voltage and high-resistance element is formed in an interlayer insulating film. And, in Patent Document 1, it is described that the spiral high-voltage and high-resistance element is used as the resistor on the high-potential side of a resistance voltage-dividing circuit, and an ordinary resistor is used as the resistor on the low-potential side of the resistance voltage-dividing circuit to detect an input voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, for example, when the switching power supply is a power factor correction circuit and the capacitance of the input capacitor is very small, a high voltage may be applied between the input terminal (start-up terminal) and the reference potential terminal of the control IC for the switching power supply due to a surge voltage or the like.

[0005] For this countermeasure, the withstand voltage of the spiral high-voltage and high-resistance element is required to be, for example, 800 V or more. And, assuming that 800 V is applied between the input terminal (start-up terminal) and the reference potential terminal, the resistance voltage-dividing ratio of the resistance voltage-dividing circuit, that is, the resistance value on the low-potential side, is set.

[0006] If the voltage tolerance threshold for the resistive voltage divider of a switching power supply control IC is, for example, 50V, then the resistive voltage divider circuit will divide the input voltage into 1 / 16th (=50 / 800). Consequently, it becomes difficult to ensure detection accuracy when a normal voltage (lower than 800V) is input, without surge voltages, etc. In other words, the resistive voltage divider circuit will have a large voltage detection error. Furthermore, the input circuit in the switching power supply control IC that receives the resistive voltage divider needs to withstand a high voltage (for example, 50V).

[0007] Furthermore, it is conceivable to add a voltage clamping circuit to a spiral-shaped high-voltage, high-resistance element to clamp the input voltage with a margin (e.g., 40V) above the voltage actually detected by the switching power supply control IC (e.g., 30V). This would allow the voltage division ratio of the resistive voltage divider circuit to be set to match the voltage actually detected.

[0008] However, because spiral-shaped high-voltage, high-resistance elements have high resistance, the voltage clamp circuit will have a large voltage detection error unless it is a circuit that suppresses leakage current to an extreme degree.

[0009] This disclosure aims to suppress voltage detection errors. [Means for solving the problem]

[0010] A semiconductor device according to one aspect of this disclosure is A Resurf MOSFET including a MOSFET section and a spiral-shaped spiral resistor section, A first transistor and a second transistor of the first conductivity type, and a third transistor of the second conductivity type, One or more detection circuits, Includes, The drain of the MOSFET section is electrically connected to a first terminal to which a first voltage is input, the gate is electrically connected to the first terminal via a pull-up resistor, and the source is electrically connected to a second terminal which is electrically connected to one end of an external capacitor. One end of the spiral resistor element is electrically connected to the first terminal. The drain and gate of the first transistor are electrically connected to the other end of the spiral resistor element, and the source is electrically connected to a third terminal that is electrically connected to a reference potential. The gate of the second transistor is electrically connected to the gate of the first transistor, its source is electrically connected to the third terminal, and its drain is electrically connected to the first node, thereby configuring the first and second transistors as a current mirror circuit. The drain and gate of the third transistor are electrically connected to the first node, and the source is electrically connected to the second node to which the second voltage is supplied, so that the second transistor and the third transistor are configured as a current mirror circuit. The detection circuit outputs a detection signal based on the current flowing through the third transistor. It is characterized by the following:

[0011] In the aforementioned semiconductor device, The detection circuit is A fourth transistor of second conductivity type, wherein the gate is electrically connected to the first node and the source is electrically connected to the second node, One end is electrically connected to the drain of the fourth transistor, and the other end is electrically connected to the third terminal, Includes, The detection signal representing the first voltage is output from between the drain of the fourth transistor and one end of the resistor. This also includes, It is characterized by the following:

[0012] In the aforementioned semiconductor device, The gate width ratios of the third transistor and the fourth transistor in the multiple detection circuits are different. It is characterized by the following:

[0013] In the aforementioned semiconductor device, A control circuit that operates using the third voltage generated at the second terminal and outputs a control signal for controlling a switching element of a power supply device to a fourth terminal based on the detection signal further comprising characterized in that

[0014] In the semiconductor device the detection circuit a fourth transistor of a second conductivity type having a gate electrically connected to the first node, a source electrically connected to the second node, and a drain electrically connected to a third node; a constant current circuit that outputs a constant current to the third node; a capacitor having one end electrically connected to the third node and the other end electrically connected to the third terminal; a comparison circuit having one end electrically connected to the third node, a comparison reference voltage input to the other end, and outputting the detection signal indicating that the voltage of the capacitor has become equal to or higher than the comparison reference voltage; comprising characterized in that

[0015] In the semiconductor device a control circuit that operates using the third voltage generated at the second terminal and outputs a control signal for controlling a switching element of a power supply device to a fourth terminal based on the detection signal further comprising characterized in that

[0016] In the semiconductor device the detection circuit a discharge circuit that does not discharge the capacitor when the control signal is at the first level and discharges the capacitor when the control signal is at the second level further comprising the control circuit outputs the comparison reference voltage to the other end of the comparison circuit, and changes the control signal from the first level to the second level when the detection signal indicates that the voltage of the capacitor has become equal to or higher than the comparison reference voltage It is characterized by the following:

[0017] A control device for a power supply device in one aspect of this disclosure is: Including the aforementioned semiconductor device, It is characterized by the following: [Effects of the Invention]

[0018] According to this disclosure, voltage detection errors can be suppressed. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 shows the configuration of the power supply device according to the first embodiment. [Figure 2] Figure 2 shows the configuration of the semiconductor device of the first comparative example. [Figure 3] Figure 3 shows the configuration of the semiconductor device according to the first embodiment. [Figure 4] Figure 4 shows the configuration of the semiconductor device of the second comparative example. [Figure 5] Figure 5 shows the configuration of the semiconductor device according to the second embodiment. [Figure 6] Figure 6 shows the configuration of the semiconductor device of the third comparative example. [Figure 7] Figure 7 shows the configuration of a semiconductor device according to the third embodiment. [Modes for carrying out the invention]

[0020] The embodiments of this disclosure will be described in detail below with reference to the attached drawings. However, this embodiment does not limit the disclosure, and in the following embodiments, the same parts are denoted by the same reference numerals to avoid redundant explanations.

[0021] <First Embodiment> (Power supply unit configuration) Figure 1 shows the configuration of the power supply device according to the first embodiment.

[0022] Terminal 1a of power supply unit 1 is electrically connected to one end of AC power supply 2. Terminal 1b of power supply unit 1 is electrically connected to the other end of AC power supply 2. Terminal 1c of power supply unit 1 is electrically connected to one end of load 3. Terminal 1d of power supply unit 1 is electrically connected to the other end of load 3.

[0023] Power supply unit 1 converts the AC voltage Vin input from AC power supply 2 between terminals 1a and 1b into a DC voltage Vout, and outputs the DC voltage Vout to load 3 from between terminals 1c and 1d.

[0024] In this embodiment, the power supply unit 1 is a converter, but this disclosure is not limited thereto. The power supply unit 1 may also be an inverter.

[0025] The power supply unit 1 includes a rectifier circuit 11, a capacitor 12, a capacitor 13, a diode 14, a semiconductor device 15, a switching element 16, a transformer 17, a diode 18, and a capacitor 19.

[0026] The transformer 17 includes a first winding 17a, a second winding 17b, and a core 17c. The first winding 17a and the second winding 17b are wound around the core 17c.

[0027] In this embodiment, the first winding 17a and the second winding 17b are windings of the transformer 17, but this disclosure is not limited thereto. The first winding 17a and the second winding 17b only need to be electromagnetically coupled to each other.

[0028] Terminal 11a of the rectifier circuit 11 is electrically connected to terminal 1a. Terminal 11b of the rectifier circuit 11 is electrically connected to terminal 1b. Terminal 11d of the rectifier circuit 11 is electrically connected to a reference potential. The reference potential is exemplified by, but is not limited to, the ground potential. The rectifier circuit 11 rectifies (e.g., full-wave rectification, half-wave rectification, etc.) the AC voltage Vin input between terminals 11a and 11b, and outputs the rectified voltage between terminals 11c and 11d.

[0029] The rectifier circuit 11 is exemplified by a bridge diode and is exemplified by full-wave rectification, but is not limited thereto.

[0030] The high-potential side of capacitor 12 is electrically connected to terminal 11c. The low-potential side of capacitor 12 is electrically connected to terminal 11d. Capacitor 12 smooths the voltage output from the rectifier circuit 11 and outputs the smoothed voltage V1.

[0031] The voltage V1 across capacitor 12 corresponds to an example of the "first voltage" in this disclosure.

[0032] The switching element 16, the first winding 17a, and the diode 18 constitute a step-up / step-down chopper circuit 20.

[0033] In this embodiment, the power supply unit 1 includes a step-up / step-down chopper circuit 20, but this disclosure is not limited thereto. The power supply unit 1 may also include a step-up chopper circuit, a step-down chopper circuit, etc.

[0034] The source of the switching element 16 is electrically connected to the low-potential side of the capacitor 12. The gate of the switching element 16 is electrically connected to terminal 15d of the semiconductor device 15. The semiconductor device 15 outputs a switching control signal S1 from terminal 15d to the gate of the switching element 16, thereby controlling the switching element 16 on and off. The drain of the switching element 16 is electrically connected to one end of the first winding 17a and the anode of the diode 18.

[0035] The other end of the first winding 17a is electrically connected to the high-potential side of capacitor 12, the low-potential side of capacitor 19, and terminal 1d.

[0036] The cathode of diode 18 is electrically connected to the high-potential side terminal and terminal 1c of capacitor 19.

[0037] In the step-up / step-down chopper circuit 20, when the switching element 16 is ON, current flows through the path from the high-potential end of the capacitor 12 → the other end of the first winding 17a → one end of the first winding 17a → the drain of the switching element 16 → the source of the switching element 16 → the low-potential end of the capacitor 12. As a result, electromagnetic energy is stored in the first winding 17a.

[0038] Furthermore, when the switching element 16 is in the off state, current flows through the path from one end of the first winding 17a → the anode of the diode 18 → the cathode of the diode 18 → the high-potential end of the capacitor 19 and the high-potential end of the load 3 → the low-potential end of the capacitor 19 and the low-potential end of the load 3 → to the other end of the first winding 17a. As a result, the electromagnetic energy of the first winding 17a is released.

[0039] In addition to its basic function of controlling the DC voltage Vout to a desired voltage, the step-up / step-down chopper circuit 20 is equipped with various protection functions. For example, it may have an undervoltage protection function that shuts off the power supply when the voltage V1 is too low, a function that determines whether the input voltage is 100V or 200V based on the voltage V1 and switches to the appropriate threshold voltage (e.g., the threshold voltage for overcurrent detection), or, in the case of a power factor correction power supply, a function that corrects the on-width or on-duty cycle based on the value of the voltage V1 to improve total harmonic distortion (THD). The acquisition of the voltage value of the voltage V1 will be explained later.

[0040] One end of the second winding 17b of transformer 17 is electrically connected to the reference potential. The other end of the second winding 17b is electrically connected to the anode of diode 14. The cathode of diode 14 is electrically connected to the high-potential side of capacitor 13. The low-potential side of capacitor 13 is electrically connected to the reference potential.

[0041] Terminal 15a of the semiconductor device 15 is electrically connected to the high-potential side of the capacitor 12. Terminal 15b of the semiconductor device 15 is electrically connected to the high-potential side of the capacitor 13. Terminal 15c of the semiconductor device 15 is electrically connected to the reference potential. Terminal 15d of the semiconductor device 15 is electrically connected to the gate of the switching element 16.

[0042] Terminal 15a corresponds to an example of the “first terminal” of this disclosure. Terminal 15b corresponds to an example of the “second terminal” of this disclosure. Terminal 15c corresponds to an example of the “third terminal” of this disclosure. Terminal 15d corresponds to an example of the “fourth terminal” of this disclosure.

[0043] The semiconductor device 15 operates using the voltage V2 generated across the capacitor 13 as the power supply voltage.

[0044] Voltage V2 corresponds to an example of the “third voltage” in this disclosure.

[0045] In the initial state of power supply unit 1, the voltage V2 across capacitor 13 is exemplified as zero volts. When an AC voltage Vin is input to power supply unit 1 and a voltage V1 is generated across capacitor 12, semiconductor device 15 outputs a current I2 from terminal 15b to the high-potential side of capacitor 13, based on the current I1 flowing from the high-potential side of capacitor 12 to terminal 15a. As a result, a voltage V2 is generated across capacitor 13.

[0046] The semiconductor device 15 can use voltage V2 as the power supply voltage and start controlling the buck-boost chopper circuit 20.

[0047] When the semiconductor device 15 starts controlling the step-up / step-down chopper circuit 20 and current flows through the first winding 17a, an induced current I3 flows through the second winding 17b. The induced current I3 flows through the diode 14 to the high-potential side of the capacitor 13.

[0048] Thus, when the step-up / step-down chopper circuit 20 starts operating, the capacitor 13 becomes charged by the induced current I3. Consequently, the semiconductor device 15 can stop outputting the current I2.

[0049] (Semiconductor device of the first comparative example) Figure 2 shows the configuration of the semiconductor device of the first comparative example.

[0050] The semiconductor device 150 includes a startup circuit 31, a control circuit 32, and a resistor 151.

[0051] The startup circuit 31 includes a RESURF (Reduced Surface Field) MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 41, a pull-up resistor 42, a first-conductivity type transistor 43, a current limiting circuit 44, and a Zener diode 45.

[0052] In this disclosure, the first conductivity type is assumed to be an N-channel type, but this disclosure is not limited thereto.

[0053] The startup circuit 31 is a circuit that, in the initial state of the power supply unit 1, outputs a current I2 to the capacitor 13, generates a voltage V2 across the capacitor 13, and starts up the control circuit 32.

[0054] The Resurf MOSFET 41 includes a first-conductivity type MOSFET section 41a and a spiral-shaped spiral resistor section 41b.

[0055] The drain of MOSFET section 41a is electrically connected to terminal 15a. The gate of MOSFET section 41a is electrically connected to one end of pull-up resistor 42. The other end of pull-up resistor 42 is electrically connected to terminal 15a. The source of MOSFET section 41a is electrically connected to one end of current limiting circuit 44. The other end of current limiting circuit 44 is electrically connected to terminal 15b and control circuit 32.

[0056] When the power supply unit 1 is initially connected, a voltage V1 is input to terminal 15a, and the gate of the MOSFET unit 41a is pulled up by the voltage V1, causing the MOSFET unit 41a to turn on. Then, current I1 flows from terminal 15a to the drain of the MOSFET unit 41a, and current I2 flows from the source of the MOSFET unit 41a to the current limiting circuit 44, then to terminal 15b, and finally to the high-potential end of the capacitor 13. As a result, the capacitor 13 is charged.

[0057] The current limiting circuit 44 limits the maximum value of the current I2, preventing large inrush currents from flowing into the capacitor 13 and the control circuit 32.

[0058] One end of the spiral resistor element 41b is electrically connected to terminal 15a. The other end of the spiral resistor element 41b is electrically connected to one end of resistor 151. The other end of resistor 151 is electrically connected to terminal 15c.

[0059] In other words, the spiral resistor element 41b and the resistor 151 constitute a resistive voltage divider circuit 152. The resistive voltage divider circuit 152 divides the voltage V1 using resistance. The voltage V151 after resistance division is input to the input circuit 101 in the control circuit 32. The input circuit 101 can obtain the voltage value of voltage V1 based on the voltage V151.

[0060] The control circuit 32 operates using the voltage V2 generated across the capacitor 13 as the power supply voltage. The control circuit 32 operates various protection and correction functions based on the voltage value of voltage V1 obtained from the voltage value of voltage V151. The control circuit 32 outputs a switching control signal S1 to the gate of the switching element 16 via terminal 15d.

[0061] The drain of transistor 43 is electrically connected to one end of pull-up resistor 42 and the gate of MOSFET section 41a. The source of transistor 43 is electrically connected to terminal 15c. Signal S11 is input to the gate of transistor 43 from control circuit 32. In the initial state of power supply 1, signal S11 is low level, and transistor 43 is in the off state. The cathode of Zener diode 45 is electrically connected to the drain of transistor 43. The anode of Zener diode 45 is electrically connected to the source of transistor 43. The Zener voltage of Zener diode 45 is exemplified as 18V, but is not limited to this disclosure. The presence of Zener diode 45 eliminates the need for a high voltage rating for transistor 43.

[0062] As mentioned above, when the buck-boost chopper circuit 20 starts operating, the capacitor 13 is charged by the induced current I3. Therefore, the startup circuit 31 no longer needs to output current I2. So the control circuit 32 changes the signal S11 from low level to high level. As a result, the transistor 43 turns on, and the gate of the MOSFET section 41a goes low. As a result, the MOSFET section 41a turns off, and the startup circuit 31 stops outputting current I2.

[0063] (Advantages of the semiconductor device in the first comparative example) The semiconductor device 150 can use a single terminal 15a to both receive a current I1 and detect the voltage value of voltage V1.

[0064] Generally, providing high-voltage, high-resistance elements inside a semiconductor device requires chip area. However, the semiconductor device 150 can suppress the increase in chip area by utilizing the spiral resistance element portion 41b of the Resurf MOSFET 41 already provided in the startup circuit 31.

[0065] (Disadvantages of the semiconductor device in the first comparative example) For example, if the power supply unit 1 is a power factor correction circuit and the capacitance of the capacitor 12 is very small, a high voltage may be applied between terminals 15a and 15c due to surge voltage or the like.

[0066] To address this issue, the voltage rating of the spiral resistor element 41b is required to be, for example, 800V or higher. The resistance division ratio of the resistor voltage divider circuit 152, i.e., the resistance value of resistor 151, is then set assuming that 800V is applied between terminals 15a and 15c.

[0067] If the voltage tolerance threshold of the input circuit 101 is, for example, 50V, then the resistive voltage divider circuit 152 will divide the voltage V1 into 1 / 16 (=50 / 800). Consequently, it becomes difficult for the resistive voltage divider circuit 152 to ensure detection accuracy when a normal voltage V1 (lower than 800V) without surge voltages or other issues is input. In other words, the resistive voltage divider circuit 152 will have a large voltage detection error. Furthermore, the input circuit 101 will need to withstand a high voltage V151 (for example, 50V).

[0068] Furthermore, it is also conceivable to add a voltage clamp circuit to the spiral resistor element section 41b to clamp the voltage V1 with a voltage (for example, 40V) that provides a margin over the voltage V151 (for example, 30V) actually output by the resistor voltage divider circuit 152, thereby setting the voltage division ratio of the resistor voltage divider circuit 152 to match the voltage division ratio of the voltage V151 actually detected.

[0069] However, because the spiral resistor element 41b has high resistance, the voltage clamp circuit must be a circuit that suppresses leakage current to an extreme degree, otherwise the voltage detection error will be large.

[0070] (Semiconductor device of the first embodiment) Figure 3 shows the configuration of the semiconductor device according to the first embodiment. Components of the semiconductor device 15 that are the same as those of the semiconductor device 150 are denoted by the same reference numerals, and their descriptions are omitted.

[0071] The semiconductor device 15 does not have a resistor 151 compared to the semiconductor device 150. Furthermore, the semiconductor device 15 further includes a first-conductivity type transistor 33, a first-conductivity type transistor 34, a second-conductivity type transistor 35, and a detection circuit 36 ​​compared to the semiconductor device 150.

[0072] In this disclosure, the second conductivity type is assumed to be a P-channel type, but this disclosure is not limited thereto.

[0073] Transistor 33 corresponds to an example of the “first transistor” in this disclosure. Transistor 34 corresponds to an example of the “second transistor” in this disclosure. Transistor 35 corresponds to an example of the “third transistor” in this disclosure.

[0074] The drain and gate of transistor 33 are electrically connected to the other end of the spiral resistor element 41b. The source of transistor 33 is electrically connected to terminal 15c. In other words, transistor 33 is diode-connected.

[0075] A current I11 flows between the drain and source of transistor 33, corresponding to the voltage V1.

[0076] The source of transistor 34 is electrically connected to terminal 15c. The gate of transistor 34 is electrically connected to the gate and drain of transistor 33. In other words, transistors 33 and 34 form a current mirror circuit. The drain of transistor 34 is electrically connected to node N1.

[0077] The current I12 flowing between the drain and source of transistor 34 is the same as the current I11.

[0078] Node N1 corresponds to an example of the “first node” in this disclosure.

[0079] The drain and gate of transistor 35 are electrically connected to node N1. The source of transistor 35 is electrically connected to node N2. In other words, transistor 35 is diode-connected.

[0080] The control circuit 32 outputs a predetermined voltage V11 to node N2. While 5V is an example of the predetermined voltage V11, this disclosure is not limited to this value.

[0081] Node N2 corresponds to an example of the “second node” in this disclosure.

[0082] The source-drain path of transistor 35 and the drain-source path of transistor 34 are connected in series. Therefore, a current I12 flows between the source and drain of transistor 35.

[0083] The detection circuit 36 ​​outputs a detection signal S12, which represents the voltage value of voltage V1, to the input circuit 102 in the control circuit 32, based on the current I12.

[0084] The detection circuit 36 ​​includes a second-conductivity transistor 51 and a resistor 52.

[0085] The source of transistor 51 is electrically connected to node N2. The gate of transistor 51 is electrically connected to node N1. In other words, transistors 35 and 51 form a current mirror circuit.

[0086] The current I21 flowing between the source and drain of transistor 51 is the same as the current I12 and the same as the current I11. In other words, current I21 is the current corresponding to voltage V1.

[0087] One end of resistor 52 is electrically connected to the drain of transistor 51. The other end of resistor 52 is electrically connected to terminal 15c.

[0088] A current I21 corresponding to the voltage V1 flows through resistor 52, generating a voltage V21 corresponding to the voltage V1. The voltage V21 at one end of resistor 52 is input to input circuit 102 as detection signal S12. Based on the detection signal S12, input circuit 102 can obtain the voltage value of voltage V1.

[0089] The resistance value of resistor 52 can be set to an appropriate value so that a detection signal S12 of the desired voltage level is obtained.

[0090] Alternatively, the gate width of transistor 51 can be set to an appropriate value so that a detection signal S12 of the desired voltage level is obtained. In that case, the gate widths of transistor 35 and transistor 51 may be different.

[0091] (Effects of the semiconductor device of the first embodiment) Transistor 33 does not require a high voltage rating because it is clamped by a drain-source threshold voltage. Transistors 34, 35, and 51 only need to withstand a voltage of V11 (e.g., 5V).

[0092] Even if a high voltage (e.g., 800V) is applied between terminals 15a and 15c due to surge voltage or the like, the voltage applied to transistors 34, 35, and 51 will not exceed V11. Therefore, the input circuit 102 does not require a high voltage rating.

[0093] Furthermore, the voltage V21 (i.e., the detection signal S12) will never be higher than the voltage V11 (for example, 5V). In other words, the voltage V21 is clamped to the voltage V11.

[0094] Therefore, unlike the resistor voltage divider circuit 152 of the first comparative example, the detection circuit 36 ​​does not need to divide the voltage V21 to a lower voltage (for example, to 1 / 16) in consideration of surge voltages (for example, 800V). In other words, the detection circuit 36 ​​can set the resistance value of resistor 52 assuming only that a normal voltage V1 without surge voltages (lower than 800V) is input to terminal 15a.

[0095] This allows the semiconductor device 15 to suppress voltage detection errors.

[0096] Furthermore, the semiconductor device 15 does not require the addition of a voltage clamp circuit to the spiral resistor element section 41b. Therefore, the semiconductor device 15 does not experience errors due to leakage current in the voltage clamp circuit.

[0097] <Second Embodiment> (Semiconductor device of the second comparative example) Figure 4 shows the configuration of the semiconductor device of the second comparative example. Among the components of semiconductor device 150A, components that are the same as those of semiconductor device 150 are given the same reference numerals and their descriptions are omitted.

[0098] Compared to semiconductor device 150, semiconductor device 150A further includes operational amplifiers 153 to 155.

[0099] The non-inverting input terminal (+ terminal) of the operational amplifier 153 is electrically connected to one end of the resistor 151. The inverting input terminal (- terminal) of the operational amplifier 153 is electrically connected to the output terminal of the operational amplifier 153. In other words, negative feedback is applied to the operational amplifier 153. The operational amplifier 153 outputs a detection signal S151 corresponding to the voltage V151 to the input circuit 103 in the control circuit 32.

[0100] The input circuit 103 can obtain the voltage value of voltage V1 based on the detection signal S151.

[0101] The non-inverting input terminal (+ terminal) of the operational amplifier 154 is electrically connected to one end of the resistor 151. The inverting input terminal (- terminal) of the operational amplifier 154 is electrically connected to the output terminal of the operational amplifier 154. In other words, the operational amplifier 154 is subjected to negative feedback. The operational amplifier 154 outputs a detection signal S152 corresponding to the voltage V151 to the input circuit 104 in the control circuit 32.

[0102] The input circuit 104 can obtain the voltage value of voltage V1 based on the detection signal S152.

[0103] The non-inverting input terminal (+ terminal) of the operational amplifier 155 is electrically connected to one end of the resistor 151. The inverting input terminal (- terminal) of the operational amplifier 155 is electrically connected to the output terminal of the operational amplifier 155. In other words, the operational amplifier 155 is subjected to negative feedback. The operational amplifier 155 outputs a detection signal S152 corresponding to the voltage V151 to the input circuit 105 in the control circuit 32.

[0104] The input circuit 105 can obtain the voltage value of voltage V1 based on the detection signal S153.

[0105] (Disadvantages of the semiconductor device in the second comparative example) The control circuit 32 may need to obtain the voltage value of voltage V1 at multiple locations, namely from input circuit 103 to input circuit 105. If the input impedance of each of the input circuits from input circuit 103 to input circuit 105 cannot be ignored, the semiconductor device 150A needs to isolate the impedance of the signal paths of detection signals S151, S152, and S153.

[0106] The semiconductor device 150A includes operational amplifiers 153 to 155 to isolate the impedance of the signal paths of detection signals S151, S152, and S153.

[0107] However, even a simple circuit configuration requires eight transistors for a single operational amplifier. Therefore, semiconductor device 150A requires a total of 24 transistors to isolate the impedance of the signal paths for detection signals S152 and S153. This results in a large circuit size for semiconductor device 150A.

[0108] Furthermore, the semiconductor device 150A must determine the resistance division ratio of the resistance division circuit 152, taking into consideration surge voltages (for example, 800V).

[0109] Therefore, if, for example, operational amplifier 153 outputs a detection signal S151 for a desired voltage level when the voltage V1 is around 300V, and operational amplifier 154 outputs a detection signal S152 for a desired voltage level when the voltage V1 is around 50V, and each operational amplifier detects a different voltage V1, it becomes difficult to ensure detection accuracy because it is not possible to set the optimal resistance division ratio for each detection.

[0110] (Semiconductor device of the second embodiment) Figure 5 shows the configuration of the semiconductor device according to the second embodiment. Components of the semiconductor device 15A that are the same as those of the semiconductor device 15 are denoted by the same reference numerals, and their descriptions are omitted.

[0111] Compared to semiconductor device 15, semiconductor device 15A includes detection circuit 36-1, detection circuit 36-2, and detection circuit 36-3 instead of detection circuit 36.

[0112] In this embodiment, the number of detection circuits 36 is set to three, but this disclosure is not limited to this. The number of detection circuits 36 may be two, four or more, or more.

[0113] The detection circuit 36-1 outputs a detection signal S12-1 representing the voltage V1 to the input circuit 106 in the control circuit 32, based on the current I12.

[0114] The detection circuit 36-1 includes a second-conductivity transistor 51-1 and a resistor 52-1.

[0115] The source of transistor 51-1 is electrically connected to node N2. The gate of transistor 51-1 is electrically connected to node N1. In other words, transistor 35 and transistor 51-1 form a current mirror circuit.

[0116] The current I21-1 flowing between the source and drain of transistor 51-1 is the same as the current I12 and the same as the current I11. In other words, current I21-1 is the current corresponding to voltage V1.

[0117] One end of resistor 52-1 is electrically connected to the drain of transistor 51-1. The other end of resistor 52-1 is electrically connected to terminal 15c.

[0118] A current I21-1 flows through resistor 52-1 corresponding to the voltage V1, generating a voltage V21-1 corresponding to the voltage V1. The voltage V21-1 at one end of resistor 52-1 is input to input circuit 106 as detection signal S12-1. Based on detection signal S12-1, input circuit 106 can obtain the voltage value of voltage V1.

[0119] The resistance value of resistor 52-1 can be set to an appropriate value so that a detection signal S12-1 at the desired voltage level is obtained.

[0120] Alternatively, the gate width of transistor 51-1 can be set to an appropriate value so that a detection signal S12-1 of the desired voltage level is obtained. In that case, the gate width of transistor 35 and the gate width of transistor 51-1 may be different.

[0121] The detection circuit 36-2 outputs a detection signal S12-2 representing the voltage V1 to the input circuit 107 in the control circuit 32, based on the current I12.

[0122] The detection circuit 36-2 includes a second-conductivity transistor 51-2 and a resistor 52-2.

[0123] The source of transistor 51-2 is electrically connected to node N2. The gate of transistor 51-2 is electrically connected to node N1. In other words, transistor 35 and transistor 51-2 form a current mirror circuit.

[0124] The current I21-2 flowing between the source and drain of transistor 51-2 is the same as the current I12 and the same as the current I11. In other words, current I21-2 is the current corresponding to voltage V1.

[0125] One end of resistor 52-2 is electrically connected to the drain of transistor 51-2. The other end of resistor 52-2 is electrically connected to terminal 15c.

[0126] A current I21-2 flows through resistor 52-2, corresponding to the voltage V1, thus generating a voltage V21-2 corresponding to the voltage V1. The voltage V21-2 at one end of resistor 52-2 is input to input circuit 107 as detection signal S12-2. Based on detection signal S12-2, input circuit 107 can obtain the voltage value of voltage V1.

[0127] The resistance value of resistor 52-2 can be set to an appropriate value so that a detection signal S12-2 at the desired voltage level is obtained.

[0128] Alternatively, the gate width of transistor 51-2 can be set to an appropriate value so that a detection signal S12-2 at a desired voltage level is obtained. In that case, the gate width of transistor 35 and the gate width of transistor 51-2 may be different.

[0129] The detection circuit 36-3 outputs a detection signal S12-3 representing the voltage V1 to the input circuit 108 in the control circuit 32, based on the current I12.

[0130] The detection circuit 36-3 includes a second-conductivity transistor 51-3 and a resistor 52-3.

[0131] The source of transistor 51-3 is electrically connected to node N2. The gate of transistor 51-3 is electrically connected to node N1. In other words, transistor 35 and transistor 51-3 form a current mirror circuit.

[0132] The current I21-3 flowing between the source and drain of transistor 51-3 is the same as the current I12 and the same as the current I11. In other words, current I21-3 is the current corresponding to voltage V1.

[0133] One end of resistor 52-3 is electrically connected to the drain of transistor 51-3. The other end of resistor 52-3 is electrically connected to terminal 15c.

[0134] A current I21-3 flows through resistor 52-3, corresponding to the voltage V1, thus generating a voltage V21-3 corresponding to the voltage V1. The voltage V21-3 at one end of resistor 52-3 is input to input circuit 108 as detection signal S12-3. Based on detection signal S12-3, input circuit 108 can obtain the voltage value of voltage V1.

[0135] The resistance value of resistor 52-3 can be set to an appropriate value so that a detection signal S12-3 at the desired voltage level is obtained.

[0136] Alternatively, the gate width of transistor 51-3 can be set to an appropriate value so that a detection signal S12-3 of the desired voltage level is obtained. In that case, the gate width of transistor 35 and the gate width of transistor 51-3 may be different.

[0137] (Effects of the semiconductor device in the second embodiment) Each of transistors 51-1, 51-2, and 51-3 is in a current mirror connection with transistor 35. Therefore, detection circuits 36-1, 36-2, and 36-3 do not affect each other. In other words, semiconductor device 15A can isolate the impedance of the signal paths of detection signals S12-1, S12-2, and S12-3.

[0138] Each of the detection circuits 36-1, 36-2, and 36-3 includes one transistor and one resistor. Therefore, the semiconductor device 15A can separate the impedance of the signal paths of detection signals S12-1, S12-2, and S12-3 using only a total of three transistors and three resistors.

[0139] On the other hand, as mentioned above, the semiconductor device 150A requires a total of 24 transistors.

[0140] Therefore, the semiconductor device 15A can reduce the circuit size compared to the semiconductor device 150A.

[0141] Furthermore, detection circuits 36-1, 36-2, and 36-3 can be configured by varying the resistance values ​​of resistors 52-1, 52-2, and 52-3, or by varying the gate widths of transistors 51-1, 51-2, and 51-3.

[0142] This makes it possible for each of the detection circuits 36 to accurately detect different voltages V1, for example, by having detection circuit 36-1 output a detection signal S12-1 of a desired voltage level when the voltage V1 is around 300V, and detection circuit 36-2 output a detection signal S12-2 of a desired voltage level when the voltage V1 is around 50V.

[0143] <Third Embodiment> (Semiconductor device of the third comparative example) Figure 6 shows the configuration of the semiconductor device of the third comparative example. Among the components of semiconductor device 150B, components that are the same as those of semiconductor device 15, semiconductor device 15A, semiconductor device 150, or semiconductor device 150A are denoted by the same reference numerals and their descriptions are omitted.

[0144] Compared to semiconductor device 150, semiconductor device 150B further includes a voltage-to-current conversion circuit 156, a detection circuit 37, and a buffer circuit 38.

[0145] A switching control signal S1 is input to the input terminal of the buffer circuit 38 from the control circuit 32. The buffer circuit 38 outputs the switching control signal S1 to the gate of the switching element 16 via terminal 15d.

[0146] The voltage-to-current conversion circuit 156 converts the voltage V151 into the current I151.

[0147] The voltage-to-current conversion circuit 156 includes an operational amplifier 161, a resistor 162, a first-conductivity transistor 163, a resistor 164, and a second-conductivity transistor 165.

[0148] The non-inverting input terminal (+ terminal) of op-amp 161 is electrically connected to one end of resistor 151. The output terminal of op-amp 161 is electrically connected to one end of resistor 162. The other end of resistor 162 is electrically connected to the gate of transistor 163. The drain of transistor 163 is electrically connected to node N1. The source of transistor 163 is electrically connected to the inverting input terminal (- terminal) of op-amp 161. In other words, op-amp 161 is negatively feedbacked. One end of resistor 164 is electrically connected to the source of transistor 163 and the inverting input terminal (- terminal) of op-amp 161. The other end of resistor 164 is electrically connected to terminal 15c.

[0149] The operational amplifier 161 outputs an output voltage from its output terminal to one end of resistor 162 such that the voltage at the non-inverting input terminal (+ terminal) (voltage V151) and the voltage at the inverting input terminal (- terminal) (voltage at one end of resistor 164) are the same. As a result, a current I151 corresponding to the voltage V151 flows between the drain and source of transistor 163.

[0150] The drain and gate of transistor 165 are electrically connected to node N1. The source of transistor 165 is electrically connected to node N2. In other words, transistor 165 is diode-connected.

[0151] The control circuit 32 outputs a predetermined voltage V11 to node N2.

[0152] The source-drain path of transistor 165 and the drain-source path of transistor 163 are connected in series. Therefore, a current I151 flows between the source and drain of transistor 165.

[0153] The detection circuit 37 detects the time corrected according to the current I151, that is, the time corrected according to the voltage V1, and outputs the detection signal S154 to the input circuit 109 in the control circuit 32.

[0154] The detection circuit 37 starts timing when the switching control signal S1 becomes high and outputs a low-level detection signal S154. The detection circuit 37 outputs a high-level detection signal S154 when a time corrected according to the current I151, i.e., a time corrected according to the voltage V1, has elapsed since the start of timing.

[0155] When the detection signal S154 becomes high, the control circuit 32 changes the switching control signal S1 from high to low.

[0156] As a result, the control circuit 32 can correct and control the on-time (on-duty cycle) of the switching control signal S1 according to the voltage V1.

[0157] The detection circuit 37 includes a transistor 51, a constant current source 53, a capacitor 54, a discharge circuit 55, a comparator 56, and an inverting circuit 57.

[0158] The current I21 flowing between the source and drain of transistor 51 is the same as the current I151. In other words, current I21 is the current corresponding to voltage V1.

[0159] The drain of transistor 51 is electrically connected to node N3. Transistor 51 outputs current I21 to node N3.

[0160] One end of the constant current source 53 is electrically connected to node N2. The other end of the constant current source 53 is electrically connected to node N3. The constant current source 53 outputs a constant current I22 to node N3.

[0161] One end of capacitor 54 is electrically connected to node N3. The other end of capacitor 54 is electrically connected to terminal 51c.

[0162] The current I23 flowing from node N3 to capacitor 54 is the sum of current I21 and constant current I22. In other words, a basic constant current I22 flows into capacitor 54. Furthermore, an additional current I21 flows into capacitor 54.

[0163] A voltage V22 corresponding to the time integral (amount of stored charge) of the current I23 is generated at one end of the capacitor 54.

[0164] Current I21 is the current corresponding to voltage V1. Therefore, the voltage V22 rises more slowly when voltage V1 is relatively low, and rises more quickly when voltage V1 is relatively high.

[0165] The discharge circuit 55 includes a diode 61 and a first-conductivity type transistor 62.

[0166] The anode of diode 61 is electrically connected to one end of capacitor 54. The cathode of diode 61 is electrically connected to the drain of transistor 62. The source of transistor 62 is electrically connected to terminal 15c. The gate of transistor 62 receives a logic inversion signal of the switching control signal S1 from the inverting circuit 57.

[0167] Transistor 62 is in the off state when the switching control signal S1 is at a high level, and in the on state when the switching control signal S1 is at a low level.

[0168] When transistor 62 is turned on, current flows through the path from one end of capacitor 54 → diode 61 → transistor 62 → terminal 15c. This causes capacitor 54 to discharge.

[0169] When transistor 62 is turned off, the above current does not flow. As a result, capacitor 54 is charged.

[0170] In other words, the discharge circuit 55 does not discharge the capacitor 54 when the switching control signal S1 is at a high level, and discharges the capacitor 54 when the switching control signal S1 is at a low level.

[0171] The non-inverting input terminal (+ terminal) of comparator 56 is electrically connected to one end of capacitor 54. The inverting input terminal (- terminal) of comparator 56 receives the comparison reference voltage V12 from the control circuit 32.

[0172] The reference voltage V12 may be variable. The reference voltage V12 may also be a feedback voltage from a part within the power supply unit 1.

[0173] The comparator 56 compares the voltage V22 with the reference voltage V12. If the voltage V22 is less than the reference voltage V12, the comparator 56 outputs a low-level detection signal S154 to the input circuit 109 in the control circuit 32. If the voltage V22 is equal to or greater than the reference voltage V12, the comparator 56 outputs a high-level detection signal S154 to the input circuit 109 in the control circuit 32.

[0174] When the detection signal S154 becomes high, the control circuit 32 changes the switching control signal S1 from high to low.

[0175] As a result, the control circuit 32 can correct and control the on-time (on-duty cycle) of the switching control signal S1 according to the voltage V1. Specifically, the control circuit 32 shortens the on-time of the switching control signal S1 relatively as the voltage V1 is relatively high, and lengthens the on-time of the switching control signal S1 relatively as the voltage V1 is relatively low.

[0176] (Disadvantages of the semiconductor device in the third comparative example) The detection circuit 37 outputs a detection signal S154 that has been corrected according to the current I151. For this purpose, the semiconductor device 150B requires a voltage-to-current conversion circuit 156 to convert the voltage V151 into a current I151.

[0177] As mentioned earlier, even a simple operational amplifier requires eight transistors. Therefore, the voltage-to-current conversion circuit 156 requires a total of ten transistors and two resistors to convert the voltage V151 to the current I151. This results in a large circuit size for the semiconductor device 150B.

[0178] (Semiconductor device of the third embodiment) Figure 7 shows the configuration of the semiconductor device according to the third embodiment. Components of the semiconductor device 15B that are the same as those of the semiconductor device 15 or semiconductor device 150B are denoted by the same reference numerals, and their descriptions are omitted.

[0179] Compared to semiconductor device 15, semiconductor device 15B includes a detection circuit 37 instead of a detection circuit 36.

[0180] The detection circuit 37 detects the time corresponding to the current I12, that is, the time corrected according to the voltage V1, and outputs the detection signal S13 to the input circuit 110 in the control circuit 32.

[0181] The detection circuit 37 starts timing when the switching control signal S1 becomes high and outputs a low-level detection signal S13. The detection circuit 37 outputs a high-level detection signal S13 when a time corrected according to the current I12, i.e., a time corrected according to the voltage V1, has elapsed since the start of timing.

[0182] When the detection signal S13 becomes high, the control circuit 32 changes the switching control signal S1 from high to low.

[0183] As a result, the control circuit 32 can correct and control the on-time (on-duty cycle) of the switching control signal S1 according to the voltage V1. Specifically, the control circuit 32 shortens the on-time of the switching control signal S1 relatively as the voltage V1 is relatively high, and lengthens the on-time of the switching control signal S1 relatively as the voltage V1 is relatively low.

[0184] (Effects of the semiconductor device of the third embodiment) The semiconductor device 15B can obtain a current I12 using only three transistors 33, 34, and 35.

[0185] On the other hand, as mentioned above, the voltage-to-current conversion circuit 156 of the semiconductor device 150B of the third comparative example requires a total of 10 transistors and a total of 2 resistors to obtain the current I151.

[0186] Therefore, the semiconductor device 15B can reduce the circuit size compared to the semiconductor device 150B.

[0187] <Note> The first or second embodiment may be combined with the third embodiment.

[0188] That is, the semiconductor device 15 may further include a detection circuit 37 in addition to the detection circuit 36. Also, the semiconductor device 15A may further include a detection circuit 37 in addition to detection circuits 36-1, 36-2, and 36-3.

[0189] While embodiments of the present disclosure have been described above, the present disclosure is not limited by the content of these embodiments. Furthermore, the aforementioned components include those that are readily conceivable to those skilled in the art, those that are substantially identical, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above. [Explanation of Symbols]

[0190] 1 Power supply 2 AC power supply 3 load 11 Rectifier circuit 12, 13, 19, 54 Capacitors 14, 18, 61 diodes 15 Semiconductor Equipment 16 Switching elements 17 Transformers 20. Step-up / Step-down Chopper Circuit 31 Startup Circuit 32 Control circuits 41 Resurf MOSFET 42 pull-up resistors 33, 34, 35, 43, 51, 51-1, 51-2, 51-3, 62 transistors 36, 36-1, 36-2, 36-3 detection circuit 37 Detection Circuit 38 Buffer Circuit 44 Current Limiting Circuit 52, 52-1, 52-2, 52-3 resistors 53 Constant current source 55 Discharge circuit 56 Comparator 57 Inverting Circuit

Claims

1. A Resurf MOSFET including a MOSFET section and a spiral-shaped spiral resistor section, A first transistor and a second transistor of the first conductivity type, and a third transistor of the second conductivity type, One or more detection circuits, Includes, The drain of the MOSFET section is electrically connected to a first terminal to which a first voltage is input, the gate is electrically connected to the first terminal via a pull-up resistor, and the source is electrically connected to a second terminal which is electrically connected to one end of an external capacitor. One end of the spiral resistor element is electrically connected to the first terminal. The drain and gate of the first transistor are electrically connected to the other end of the spiral resistor element, and the source is electrically connected to a third terminal that is electrically connected to a reference potential. The gate of the second transistor is electrically connected to the gate of the first transistor, its source is electrically connected to the third terminal, and its drain is electrically connected to the first node, thereby configuring the first and second transistors as a current mirror circuit. The drain and gate of the third transistor are electrically connected to the first node, and the source is electrically connected to the second node to which the second voltage is supplied, so that the second transistor and the third transistor are configured as a current mirror circuit. The detection circuit outputs a detection signal based on the current flowing through the third transistor. A semiconductor device characterized by the following features.

2. The detection circuit is A fourth transistor of second conductivity type, wherein the gate is electrically connected to the first node and the source is electrically connected to the second node, One end is electrically connected to the drain of the fourth transistor, and the other end is electrically connected to the third terminal, with respect to a resistor. Includes, The detection signal representing the first voltage is output from between the drain of the fourth transistor and one end of the resistor. The semiconductor device according to claim 1, characterized in that

3. The gate width ratios of the third transistor and the fourth transistor in the multiple detection circuits are different. The semiconductor device according to claim 2, characterized in that

4. A control circuit that operates using the third voltage generated at the second terminal and outputs a control signal to the fourth terminal to control the switching elements of the power supply based on the detection signal. This also includes, The semiconductor device according to claim 1, characterized in that

5. The detection circuit is A fourth transistor of second conductivity type, wherein the gate is electrically connected to the first node, the source is electrically connected to the second node, and the drain is electrically connected to the third node. A constant current circuit that outputs a constant current to the third node, A capacitor having one end electrically connected to the third node and the other end electrically connected to the third terminal, A comparison circuit having one end electrically connected to the third node and the other end receiving a comparison reference voltage, and outputting the detection signal when the voltage of the capacitor becomes equal to or greater than the comparison reference voltage, including, The semiconductor device according to claim 1, characterized in that

6. A control circuit that operates using the third voltage generated at the second terminal and outputs a control signal to the fourth terminal to control the switching elements of the power supply based on the detection signal. This also includes, The semiconductor device according to claim 5, characterized in that

7. The detection circuit is A discharge circuit in which the capacitor is not discharged when the control signal is at a first level, and the capacitor is discharged when the control signal is at a second level. It further includes, The aforementioned control circuit is The aforementioned comparison reference voltage is output to the other end of the comparison circuit. When the detection signal indicates that the voltage of the capacitor has become equal to or greater than the comparison reference voltage, the control signal is changed from the first level to the second level. The semiconductor device according to claim 6, characterized in that...

8. A control device for a power supply, comprising a semiconductor device according to claim 4, 6, or 7.

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