Power supply device

Abstract

To make detection voltages for detecting a drop in input voltage uniform for AC input voltage and DC input voltage.SOLUTION: A power supply device has a pair of input terminals, a bridge rectifier circuit, a voltage divider circuit, an attenuation circuit, and a voltage drop detection circuit. A DC input voltage and an AC input voltage having an effective value substantially equal to the DC input voltage are applied to the input terminal. The bridge rectifier circuit has an AC input terminal connected to the input terminal and a DC output terminal connected to an input end of a load circuit. The voltage divider circuit is connected to the input terminal and outputs a midpoint voltage of the input voltage. The attenuation circuit outputs a DC output voltage obtained by attenuating a waveform of a midpoint voltage of the voltage divider circuit when a DC input voltage is applied to the input terminal at a predetermined ratio, and outputs an AC output voltage obtained by attenuating a waveform of a midpoint voltage of the voltage divider circuit when an AC input voltage is applied to the input terminal to a waveform whose peak voltage is substantially equal to the DC output voltage. The voltage drop detection circuit detects a drop in the voltage input to the input end by detecting a drop in either the DC output voltage or the AC output voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power supply device. [Background technology]

[0002] Power supplies using switching power supply circuits are in use. In recent years, power supplies have been used that adopt switching power supply circuits with a power factor correction function to provide an input current with a waveform that is approximately equal to the input voltage. In such power supplies, when the input voltage drops, the input current rises, causing problems such as increased loss in switching transistors in the switching power supply circuit. In response to this, a power supply has been proposed that includes a power failure detection circuit that detects a drop in the input voltage due to a power failure, and that performs control to stop the switching power supply circuit (flyback circuit) when the input voltage drops (see, for example, Patent Document 1).

[0003] This power failure detection circuit detects a power failure or the like based on the peak voltage of the input voltage after full-wave rectification. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-042093 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, when the power supply device is operated with a DC voltage equal to the effective value of the AC input voltage, the operating point for detecting a drop in the input voltage changes for the AC input and the DC input, and therefore, when a DC input voltage is applied, a drop in the input voltage is detected at a voltage different from the effective voltage when an AC input voltage is applied.

[0006] The present disclosure provides a power supply device that can match the detection voltage when detecting a drop in input voltage in both AC input voltage and DC input voltage. [Means for solving the problem]

[0007] The power supply device of the present disclosure includes a pair of input terminals, a bridge rectifier circuit, a voltage divider circuit, an attenuation circuit, and a voltage drop detection circuit. A DC input voltage and an AC input voltage having an effective value substantially equal to the DC input voltage are applied to the input terminal. The bridge rectifier circuit has an AC input terminal connected to the input terminal and a DC output terminal connected to the input of a load circuit. The voltage divider circuit is connected to the input terminal and outputs a midpoint voltage of the input voltage. The attenuation circuit outputs a DC output voltage obtained by attenuating a waveform of the midpoint voltage of the voltage divider circuit when the DC input voltage is applied to the input terminal at a predetermined ratio, and outputs an AC output voltage obtained by attenuating a waveform of the midpoint voltage of the voltage divider circuit when the AC input voltage is applied to the input terminal to a waveform whose peak voltage is substantially equal to the DC output voltage. The voltage drop detection circuit detects a drop in the voltage input to the input terminal by detecting a drop in either the DC output voltage or the AC output voltage. Effect of the Invention

[0008] According to the present disclosure, it is possible to make the detection voltages when detecting a drop in input voltage uniform for both AC input voltage and DC input voltage. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of the configuration of a power supply device according to a first embodiment of the present disclosure. [Diagram 2] 2 is a diagram illustrating an example of configurations of an attenuation circuit, a voltage drop detection circuit, a peak voltage detection circuit, and a start-up voltage detection circuit according to the first embodiment of the present disclosure. FIG. [Diagram 3] FIG. 1 illustrates an example of input voltage attenuation according to an embodiment of the present disclosure. [Figure 4]4 is a diagram illustrating another configuration example of the attenuation circuit and the peak voltage detection circuit according to the first embodiment of the present disclosure. FIG. [Diagram 5] 6 is a diagram illustrating an example of the configuration of a power supply device according to a second embodiment of the present disclosure. [Figure 6] FIG. 13 is a diagram illustrating a configuration example of an attenuation circuit according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order. In the following embodiments, the same components are designated by the same reference numerals, and duplicated description will be omitted. 1. First embodiment 2. Second embodiment 3. Third embodiment

[0011] 1. First Embodiment [Power supply configuration] FIG. 1 is a diagram showing a configuration example of a power supply device according to a first embodiment of the present disclosure. The diagram is a circuit diagram showing a configuration example of a power supply device 10. The power supply device 10 converts a power source such as an AC voltage source or a DC voltage source into a desired DC voltage and supplies it to other devices. Here, the AC voltage source corresponds to, for example, a commercial power source. In the diagram, an AC voltage source 11 is shown. Also, the DC voltage source corresponds to, for example, a battery. In the diagram, a DC voltage source 12 is shown. The DC voltage source 12 outputs a DC voltage equal to the effective value of the output voltage of the AC voltage source 11.

[0012] The power supply device 10 includes a pair of input terminals, namely, input terminal 101 and input terminal 102, a bridge rectifier circuit 110, a DC stabilized power supply circuit 120, a voltage divider circuit 130, an attenuation circuit 140, a voltage drop detection circuit 170, a peak voltage detection circuit 150, and a startup voltage detection circuit 160.

[0013] Input terminals 101 and 102 are a pair of input terminals to which AC voltage source 11 or DC voltage source 12 is connected.

[0014] The bridge rectifier circuit 110 is a circuit that performs full-wave rectification of an AC input voltage. The bridge rectifier circuit 110 has AC input terminals connected to input terminals 101 and 102, and a DC output terminal connected to an input end of a DC stabilized power supply circuit 120. Note that the bridge rectifier circuit 110 in the figure shows an example in which the bridge rectifier circuit 110 is connected to the input terminal 101 via a fuse 103. Note that the negative terminal of the DC output terminal of the bridge rectifier circuit 110 is grounded.

[0015] The DC stabilized power supply circuit 120 is a circuit that converts the full-wave rectified waveform output from the bridge rectifier circuit 110 into a DC voltage of a desired voltage and supplies it as a power source to other devices. The DC stabilized power supply circuit 120 includes a power factor correction circuit 121, a smoothing capacitor 122, and a switching power supply circuit 123. The DC stabilized power supply circuit 120 is an example of a "load circuit" in the present disclosure.

[0016] The power factor correction circuit 121 is a circuit that makes the power factor of the DC stabilized power supply circuit 120 approximately 1. This power factor correction circuit 121 is, for example, configured with a boost chopper circuit, and performs switching of the output voltage of the bridge rectifier circuit 110 to convert it into a DC voltage of a predetermined voltage. At this time, the power factor correction circuit 121 adjusts the switching cycle so that an input current having a waveform approximately equal to the input voltage waveform flows. By providing this power factor correction circuit 121, the input voltage of the subsequent switching power supply circuit 123 can be made equal when the AC voltage source 11 is connected and when the DC voltage source 12 is connected. A known circuit can be used for the power factor correction circuit 121.

[0017] The smoothing capacitor 122 is connected to the output terminal of the power factor correction circuit 121 and smoothes the output voltage of the power factor correction circuit 121 .

[0018] The switching power supply circuit 123 is a circuit that switches the output voltage of the power factor correction circuit 121 smoothed by the smoothing capacitor 122 to convert it into a direct current of a desired voltage. A known circuit can be used for the switching power supply circuit 123. The switching power supply circuit 123 in the figure is assumed to be a forward type or flyback type circuit, and includes a transformer 124, a MOS transistor 125, and a control circuit 126. Note that only the primary winding of the transformer 124 is shown. The primary winding of the transformer 124 and the MOS transistor 125, which are connected in series, are connected to the input end of the switching power supply circuit 123.

[0019] The MOS transistor 125 performs switching to apply a pulsed AC voltage to the primary winding of the transformer 124. This AC voltage is stepped up or down by the transformer 124 and output from the secondary winding. The voltage of the secondary winding of the transformer 124 is rectified and smoothed to be converted into DC, which is output from the DC stabilized power supply circuit 120. The control circuit 126 controls the on / off ratio of the switching of the MOS transistor 125 to stabilize the output voltage of the DC stabilized power supply circuit 120. The control circuit 126 also controls the MOS transistor 125 to start switching when the voltage applied to the input terminals 101 and 102 reaches a predetermined voltage. That is, the control circuit 126 stops the switching of the MOS transistor 125 when the voltage applied to the input terminals 101 and 102 is low. Whether the voltage applied to the input terminals 101 and 102 reaches the predetermined voltage is detected by a start-up voltage detection circuit 160, which will be described later. The control circuit 126 performs control to stop the switching of the MOS transistor 125 based on a signal from the start-up voltage detection circuit 160 .

[0020] The voltage dividing circuit 130 is a circuit connected between the input terminals 101 and 102, and outputs a midpoint voltage of the input voltage. The voltage dividing circuit 130 in the figure shows an example in which it is connected to the input terminal 101 via a fuse 103. This voltage dividing circuit 130 is composed of resistors 131 and 132 connected in series. The resistors 131 and 132 can have the same resistance value. A midpoint voltage (Vvd in the figure) is output from the midpoint of the resistors 131 and 132 connected in series.

[0021] The attenuation circuit 140 is a circuit that outputs a DC output voltage obtained by attenuating, at a predetermined ratio, the waveform of the midpoint voltage of the voltage divider circuit 130 when a DC input voltage is input to the input terminals 101 and 102. The attenuation circuit 140 also outputs an AC output voltage obtained by attenuating, at a predetermined ratio, the waveform of the midpoint voltage of the voltage divider circuit 130 when an AC input voltage is applied to the input terminals 101 and 102, to a waveform whose peak voltage is approximately equal to the DC output voltage. The output of the attenuation circuit 140 (Vout2 in the figure) is output to the voltage drop detection circuit 170 and the peak voltage detection circuit 150. The configuration of the attenuation circuit 140 will be described in detail later.

[0022] The voltage drop detection circuit 170 is a circuit that detects a drop in the voltage input to the input terminals 101 and 102 by detecting a drop in either the DC output voltage or the AC output voltage from the attenuation circuit 140. The voltage drop detection circuit 170 outputs a voltage drop detection signal, which is the detection result, to an external device. The configuration of the voltage drop detection circuit 170 will be described in detail later.

[0023] The peak voltage detection circuit 150 detects and outputs the peak voltages of the DC output voltage and the AC output voltage. The peak voltage detection circuit 150 outputs the detected peak voltage (Vout1 in the figure) to the start-up voltage detection circuit 160.

[0024] The start-up voltage detection circuit 160 is a circuit that detects the rise in the output voltage of the peak voltage detection circuit 150, thereby detecting the start-up voltage of the switching power supply circuit 123. The detection result is output to the control circuit 126.

[0025] [Configuration of attenuation circuit, voltage drop detection circuit, peak voltage detection circuit and start-up voltage detection circuit] 2 is a diagram showing configuration examples of an attenuation circuit 140, a voltage drop detection circuit 170, a peak voltage detection circuit 150, and a start-up voltage detection circuit 160 according to the first embodiment of the present disclosure.

[0026] The attenuation circuit 140 includes resistors 141 to 144, a capacitor 145, and a transistor 146. The resistors 141 and 142 connected in series are connected between the input terminal and the ground line. A circuit in which the capacitor 145 connected in parallel with the resistor 143 and the resistor 144 are connected in series is connected between the input terminal and the ground line. The base of the transistor 146 is connected to the midpoint of the resistors 141 and 142 connected in series. The emitter of the transistor 146 is connected to the midpoint of the resistor 143 and the capacitor 145 connected in series. The collector of the transistor 146 is grounded. The midpoint of the resistor 143 and the capacitor 145 connected in series constitutes the output terminal of the attenuation circuit 140, and Vout2 is output from the midpoint. A pnp transistor can be used for the transistor 146.

[0027] A circuit in which a capacitor 145 connected in parallel with a resistor 143 and a resistor 144 are connected in series is a circuit that attenuates the input voltage. This circuit is composed of a voltage divider circuit in which a plurality of impedance elements including a reactance element are connected in series. By placing a reactance element in this circuit, it is possible to achieve different amounts of attenuation for the DC input voltage and the AC input voltage.

[0028] The circuit including resistors 141 and 142 and a transistor 146 is a circuit that discharges the voltage of the capacitor 145 when the input voltage (Vvd) drops. By providing this circuit, a drop in the input voltage can be detected at high speed.

[0029] The voltage drop detection circuit 170 includes a comparator 171 , a delay circuit 172 , and a signal generation circuit 173 .

[0030] The comparator 171 compares the signal (Vout2) output from the attenuation circuit 140 with a threshold voltage Vth2, and outputs an H-level signal if Vout2 is smaller than Vth2.

[0031] The delay circuit 172 is a circuit that delays the output signal of the comparator 171. This delay circuit 172 is a circuit that prevents detection of a voltage drop when the AC input voltage approaches 0 V. The delay circuit 172 delays the signal output from the comparator 171 by a predetermined time. If a signal is still output from the comparator 171 after this delay, the delay circuit 172 outputs the signal to the signal generating circuit 173.

[0032] The signal generating circuit 173 is a circuit that generates a voltage drop detection signal based on the output signal of the delay circuit 172 and outputs the signal.

[0033] The peak voltage detection circuit 150 includes a diode 151, a capacitor 152, and a resistor 153. The diode 151 has an anode connected to the input terminal and a cathode connected to the output terminal. The capacitor 152 is connected between the output terminal and a ground line. The resistor 153 is connected between the output terminal and a ground line. The diode 151 and the capacitor 152 detect the peak voltage of the output (Vout2) of the attenuation circuit 140. Vout1 in the figure represents the detected peak voltage. The resistor 153 discharges the capacitor 152 when no input voltage is applied.

[0034] The start-up voltage detection circuit 160 includes a comparator 161. This comparator 161 compares the signal (Vout1) output from the peak voltage detection circuit 150 with a threshold voltage Vth1, and outputs an H-level signal if Vout1 is greater than Vth1. This signal is transmitted to the control circuit 126.

[0035] [Damping circuit operation] FIG. 3 is a diagram showing an example of input voltage attenuation according to an embodiment of the present disclosure. The figure shows an example of input voltage attenuation in the attenuation circuit 140. The operation of the attenuation circuit 140 and the peak voltage detection circuit 150 will be described using the figure. The left side of the figure shows AC input, and the right side shows DC input. In addition, "Vvd", "Vout2", and "Vout1" in the figure show the waveforms of Vvd, Vout2, and Vout1. Note that the figure shows an outline of the signal waveforms, and is not necessarily the same as the actual ones.

[0036] Vvd when AC is input has a full-wave rectified waveform. In the figure, Vp1 represents the peak voltage, and Ve represents the effective voltage. This voltage waveform is attenuated by the attenuation circuit 140. Vout2 represents the waveform after attenuation. Vp2 represents the peak voltage of the waveform after attenuation. Next, the peak voltage is detected by the peak voltage detection circuit 150. Vout1 represents the detected peak voltage. The waveform of Vout1 is a waveform that has been rectified and smoothed from the waveform of Vout2.

[0037] When DC is input, Vvd has a DC waveform. Vdc1 in the figure represents a DC voltage. This Vdc1 is approximately the same voltage as Ve. This DC waveform is attenuated by the attenuation circuit 140 to become Vdc2. This Vdc2 is approximately the same voltage as Vp2. Also, the waveform of Vout1 is approximately the same as that of Vout2.

[0038] In this way, the attenuation circuit 140 attenuates the peak voltage Vp1 of the waveform during AC input to Vp2, which is approximately the same voltage as Vdc2 during DC input. This makes it possible to equalize the voltage of Vout2 during AC input and DC input.

[0039] Furthermore, due to the circuit action of the resistors 141 and 142 and the transistor 146 arranged in the attenuation circuit 140, when Vvd drops to a voltage close to 0 V, Vout2 can be dropped to a voltage close to 0 V. This allows the voltage drop detection circuit 170 to detect a voltage drop at high speed.

[0040] If there is no need to discharge the voltage of capacitor 145 when Vvd drops, for example, if the voltage drop detection circuit 170 is omitted, the resistors 141 and 142 and the transistor 146 of the attenuation circuit 140 can be omitted. In this case, the attenuation circuit 140 is composed of resistors 143 and 144 and the capacitor 145.

[0041] [Other configurations of the attenuation circuit and peak voltage detection circuit] 4 is a diagram showing another example of the configuration of the attenuation circuit 140 and the peak voltage detection circuit 150 according to the first embodiment of the present disclosure.

[0042] The attenuation circuit 140 in the figure includes resistors 147 and 148 connected in series instead of the resistor 144. The voltage at the midpoint of the resistors 147 and 148 connected in series is output to a voltage drop detection circuit 170. By adjusting the ratio between the resistors 147 and 148, the voltage output to the voltage drop detection circuit 170 can be adjusted.

[0043] The peak voltage detection circuit 150 in the figure includes resistors 154 and 155 connected in series instead of resistor 153. The voltage at the midpoint of the resistors 154 and 155 connected in series is output to a start-up voltage detection circuit 160. By adjusting the ratio between the resistors 154 and 155, the voltage output to the start-up voltage detection circuit 160 can be adjusted.

[0044] In this way, the power supply device 10 can make the detection voltages uniform when detecting a drop in the input voltage for both AC input voltage and DC input voltage.

[0045] 2. Second Embodiment [Power supply configuration] Fig. 5 is a diagram showing a configuration example of a power supply device according to a second embodiment of the present disclosure. Similar to Fig. 1, this figure is a circuit diagram showing a configuration example of a power supply device 10. The power supply device 10 in this figure differs from the power supply device 10 in Fig. 1 in that it further includes a buffer circuit 180.

[0046] The buffer circuit 180 is a circuit that is disposed between the voltage divider circuit 130 and the attenuation circuit 140, and separates the voltage divider circuit 130 and the attenuation circuit 140. The buffer circuit 180 can be configured, for example, by an emitter follower circuit. By disposing the buffer circuit 180, the influence of the attenuation circuit 140 on the voltage divider circuit 130 can be reduced. In contrast, without the buffer circuit 180, the attenuation circuit 140 is connected in parallel to either the resistor 131 or the resistor 132 of the voltage divider circuit 130, which causes an error in the midpoint voltage.

[0047] Other than this, the configuration of the power supply device 10 is similar to that of the power supply device 10 of the first embodiment of the present disclosure, and therefore a description thereof will be omitted.

[0048] In this manner, the power supply device 10 according to the second embodiment of the present disclosure can reduce the change in the output voltage of the voltage divider circuit 130 by providing the buffer circuit 180.

[0049] 3. Third embodiment [Attenuation circuit configuration] Fig. 6 is a diagram showing a configuration example of an attenuation circuit according to a third embodiment of the present disclosure. Similar to Fig. 2, Fig. 6 is a circuit diagram showing a configuration example of an attenuation circuit 140. The attenuation circuit 140 in Fig. 6 differs from the attenuation circuit 140 in Fig. 2 in that it further includes a correction circuit 190.

[0050] The correction circuit 190 is composed of a resistor 191 and a capacitor 192 connected in series. The correction circuit 190 is connected to the resistor 143 in parallel.

[0051] In the figure, resistors 141, 142, 143, and 144 can be set to 100 kΩ, 47 kΩ, 7.8 kΩ, and 10 kΩ, respectively. Capacitor 145 can be set to 3.3 μF. In this case, resistor 191 can be set to 100 Ω. Capacitor 192 can be set to 0.47 μF.

[0052] The compensation circuit 190 is a circuit that adjusts the attenuation of the attenuation circuit in accordance with the frequency of the AC input voltage. By providing this compensation circuit 190, the attenuation can be kept constant even when the AC input voltage changes from 50 Hz to 60 Hz.

[0053] The attenuation circuit 140 in Fig. 6 was applied to the power supply device 10 in Fig. 5, and the operation was confirmed by simulation. The simulation was performed with the gain of the buffer circuit 180 set to a value of 1. The results are as follows. (1) When a DC input voltage of 110 V is applied Vout1: 18.3V, Vout2: 18.9V (2) When AC input voltage of 110Vrms (50Hz) is applied Vout1 (peak voltage): 18.8V, Vout2 (peak voltage): 19.4V (3) When AC input voltage of 110Vrms (60Hz) is applied Vout1 (peak voltage): 18.2V, Vout2 (peak voltage): 18.7V In this way, Vout1 and Vout2 can be made uniform for DC input voltage and AC input voltage. Even if the AC input voltage changes from 50 Hz to 60 Hz, the change in Vout1 and Vout2 can be reduced by the action of the correction circuit 190.

[0054] Other than this, the configuration of the power supply device 10 is similar to that of the power supply device 10 of the first embodiment of the present disclosure, and therefore a description thereof will be omitted.

[0055] In this way, by disposing the correction circuit 190 in the attenuation circuit 140, the power supply device 10 of the third embodiment of the present disclosure can maintain the attenuation amount of the attenuation circuit 140 at a substantially constant level even when the frequency of the AC input voltage changes.

[0056] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0057] Some examples of combinations of the disclosed technical features are set out below. (1) a pair of input terminals to which a DC input voltage and an AC input voltage having an effective value substantially equal to the DC input voltage are applied; a bridge rectifier circuit having an AC input terminal connected to the input terminal and a DC output terminal connected to an input of a load circuit; a voltage divider circuit connected to the input terminal and outputting a midpoint voltage of the input voltage; an attenuation circuit which outputs a DC output voltage obtained by attenuating a waveform of the midpoint voltage of the voltage divider circuit at a predetermined ratio when the DC input voltage is applied to the input terminal, and outputs an AC output voltage obtained by attenuating a waveform of the midpoint voltage of the voltage divider circuit at a time when the AC input voltage is applied to the input terminal, to a waveform whose peak voltage is approximately equal to the DC output voltage; a voltage drop detection circuit that detects a drop in the voltage input to the input terminal by detecting a drop in either the DC output voltage or the AC output voltage; A power supply device having (2) The power supply device according to (1), wherein the attenuation circuit is constituted by a voltage divider circuit in which a plurality of impedance elements are connected in series. (3) a peak voltage detection circuit for detecting a peak voltage of the DC output voltage and the AC output voltage; a start-up voltage detection circuit that detects a rise in the output voltage of the peak voltage detection circuit to detect a start-up voltage of the load circuit; The power supply device according to (1) or (2), further comprising: (4) The power supply device according to any one of (1) to (3), further comprising a buffer circuit disposed between the voltage divider circuit and the attenuation circuit. (5) The power supply device according to any one of (1) to (4), wherein the attenuation circuit further includes a correction circuit that adjusts the output voltage in accordance with a frequency of a voltage input to the input terminal. (6) The power supply device according to any one of (1) to (5), wherein the load circuit is a DC stabilized power supply circuit. [Explanation of symbols]

[0058] 10 Power supply 11 AC voltage source 12 DC voltage source 101, 102 Input terminals 110 Bridge rectifier circuit 120 DC stabilized power supply circuit 130 Voltage divider circuit 140 Attenuation circuit 150 Peak voltage detection circuit 160 Start-up voltage detection circuit 170 Voltage drop detection circuit 180 Buffer circuit 190 Correction circuit

Claims

1. a pair of input terminals to which a DC input voltage and an AC input voltage having an effective value substantially equal to the DC input voltage are applied; a bridge rectifier circuit having an AC input terminal connected to the input terminal and a DC output terminal connected to an input terminal of a load circuit; a voltage divider circuit connected to the input terminal and outputting a midpoint voltage of the input voltage; an attenuation circuit which outputs a DC output voltage obtained by attenuating a waveform of the midpoint voltage of the voltage divider circuit at a predetermined ratio when the DC input voltage is applied to the input terminal, and outputs an AC output voltage obtained by attenuating a waveform of the midpoint voltage of the voltage divider circuit at a time when the AC input voltage is applied to the input terminal, to a waveform whose peak voltage is approximately equal to the DC output voltage; a voltage drop detection circuit that detects a drop in the voltage input to the input terminal by detecting a drop in either the DC output voltage or the AC output voltage; A power supply device having

2. 2. The power supply device according to claim 1, wherein the attenuation circuit is formed of a voltage divider circuit in which a plurality of impedance elements are connected in series.

3. a peak voltage detection circuit for detecting a peak voltage of the DC output voltage and the AC output voltage; a start-up voltage detection circuit that detects a rise in the output voltage of the peak voltage detection circuit to detect a start-up voltage of the load circuit; The power supply device according to claim 1 or 2, further comprising:

4. 3. The power supply device according to claim 1, further comprising a buffer circuit disposed between the voltage divider circuit and the attenuation circuit.

5. 3. The power supply device according to claim 1, wherein the attenuation circuit further comprises a correction circuit that adjusts the output voltage in accordance with a frequency of the voltage input to the input terminal.

6. 3. The power supply device according to claim 1, wherein the load circuit is a DC stabilized power supply circuit.

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