JP2009303455A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power supply device, capable of supplying a sufficient power while an apparatus is idle and capable of reducing a loss due to a reactive power through a starting resistance while the apparatus is active. <P>SOLUTION: A starting current is reduced by a starting time setting means while the apparatus is operated by the switching power supply. Moreover, a power necessary for the idle apparatus is supplied from the switching power supply, by exerting control so as to accelerate a starting time by the starting time setting means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a switching power supply device having intermittent oscillation state (hereinafter referred to as intermittent oscillation) control, which is one of the power consumption reduction techniques, and particularly relates to a power loss due to a starting resistor and a load correspondence range during intermittent oscillation. The present invention relates to a circuit configuration and a control method for ensuring both.

In general, a self-excited switching power supply is designed so that efficiency is maximized in a maximum load state required for a device on which the self-excited switching power supply is mounted from the viewpoint of thermal design. Therefore, the efficiency decreases as the device is stopped, that is, as the load becomes lighter. Patent Document 1 has been proposed as a method for avoiding this reduction in efficiency.
Japanese Patent No. 036921818

  However, by reducing the output of the error detection circuit of the self-excited switching power supply proposed in Patent Document 1 above at a constant frequency and duty for a time sufficient to stop the oscillation of the power supply, In the method of improving efficiency, the resistance value of the starting resistor cannot be increased in order to ensure sufficient power supply for device operation when the device is stopped. For this reason, there has been a problem that efficiency reduction due to reactive power of the starting resistor cannot be avoided during device operation.

(Basic operation of switching power supply)
A conventional switching power supply device will be described with a self-excited flyback converter (RCC: ringing choke converter) shown in FIG. 6 as a basic circuit. The insulating transformer T601 includes an input-side primary winding Np, an output-side secondary winding Ns, and a primary-side auxiliary winding Nb. The auxiliary winding Nb is a driving winding of the switching element Q602 that controls conduction / non-conduction of the control terminal of the main switching element Q601. The input voltage E is a DC voltage obtained by rectifying the AC input voltage with a bridge diode and smoothed by an aluminum electric field capacitor, and is a voltage across the aluminum electrolytic capacitor. In this figure, the bridge diode and the aluminum electrolytic capacitor are not shown. The input voltage E is applied between one end of the primary winding Np and the current outflow terminal of the main switching element Q601, the (+) side of the input voltage is one end of the primary winding Np, and the (−) side of the input voltage is The main switching element Q601 is connected to the current outflow terminal. The auxiliary winding Nb is connected to the same polarity as the primary winding Np, and the secondary winding Ns is connected to a different polarity. A starting resistor R601 is connected between the (+) side of the input voltage and the control terminal of the main switching element Q601. Further, a resistor R602 is connected between the control terminal of the main switching element Q601 and the (−) side of the DC voltage E, and the main switching element Q601 is sufficiently conductive by dividing the starting resistor R601 and the DC voltage E. Generate a large voltage. A capacitor C601 and resistors R603 and R604 are connected between the control terminal of the main switching element Q601 and the same polarity side of the primary winding of the auxiliary winding Nb. A diode D601 with the auxiliary winding Nb facing the cathode is connected to both ends of the resistor R604, and the turn-on and turn-off speed of the main switching element Q601 is adjusted. Switching element Q602 is provided to control conduction / non-conduction of main switching element Q601. The current inflow terminal is connected to the control terminal of main switching element Q601, and the current outflow terminal is connected to the (−) side of DC voltage E. The capacitor C602 is connected between the control terminal and the current outflow terminal. A resistor R605 is connected between the auxiliary winding Nb and the control terminal of the switching element Q602 to form a time constant circuit with the capacitor C602. A resistor R606 is connected between the primary current inflow terminal of the photocoupler IC 601 and the control terminal of the main switching element Q601 to limit the current flowing through the photocoupler IC601. The current outflow terminal of the phototransistor of the photocoupler IC 601 is connected to the control terminal of the switching element Q602. The anode side of the rectifying diode D602 is connected to the side opposite to the primary winding of the secondary winding Ns of the insulation transformer T601, and is the same as the cathode side of the diode D602 and the primary winding of the secondary winding Ns. An electric field capacitor C603 is connected between the pole side and the alternating voltage rectified by the diode D602 is smoothed. The output voltage Vo is divided by the resistors R607 and R608, the divided voltage is connected to the inverting input terminal of the differential amplifier IC602, and the reference voltage generated by the Zener diode ZD601 and the resistor R609 is connected to the differential amplifier IC602. The differential amplifier IC602 is input to the non-inverting input terminal, and the voltage at the output terminal is changed by comparing the input voltage at the inverting input terminal with the reference voltage, and flows to the light emitting diode of the photocoupler IC601 through the resistor R610. The current is controlled. A resistor R611 and a capacitor C604 connected between the inverting input terminal and the output terminal of the differential amplifier IC602 are for adjusting the gain and phase of the closed loop.

  The main switching element Q601 is turned on by applying a voltage to the control terminal by the starting resistor R601 and the resistor R602. When main switching element Q601 becomes conductive, input voltage E is applied to primary winding Np, and a voltage having the same polarity as the primary winding is induced in auxiliary winding Nb. At this time, a voltage is also induced in the secondary winding Ns. However, since the voltage is negative on the anode side of the rectifier diode D602, no voltage is transmitted to the secondary side. Accordingly, the current flowing through the primary winding Np is only the exciting current of the insulating transformer T601, and energy proportional to the square of the exciting current is stored in the insulating transformer T601. This exciting current increases in proportion to time. The control terminal of the main switching element Q601 is charged via the capacitor C601 and the resistors R603 and R604 by the voltage induced in the auxiliary winding Nb, and the conduction state is continued. The resistor R605 and capacitor C602 constituting the time constant circuit are charged from the auxiliary winding Nb. When the voltage across the capacitor C602 becomes higher than the threshold value of the switching element Q602, the switching element Q602 becomes conductive, and the main switching The main switching element Q601 becomes non-conductive because the control terminal voltage of the element Q601 decreases. At this time, a voltage having a polarity opposite to that at the time of starting is generated in each winding of the insulating transformer T601, and a voltage having a positive polarity on the anode side of the rectifier diode D602 is generated in the secondary winding. Therefore, the voltage is accumulated in the insulating transformer T601. Energy is rectified and smoothed and transmitted to the secondary side. When the energy stored in insulating transformer T601 is all transmitted to the secondary side, main switching element Q601 is again turned on. This is because a voltage corresponding to the winding ratio of the voltage between the current inflow and current outflow terminals of the switching element Q601 is generated in the auxiliary winding Nb, but the control terminal becomes negative immediately after the main switching element Q601 is turned off. Although the bias is biased, the negative bias gradually decreases when the transmission of energy to the secondary side ends, so the control terminal of the main switching element Q601 is again biased in the positive direction from the C-coupled capacitor C601. Because. Since a large amount of current flows from the photocoupler IC 601 when the output voltage Vo is high, a current is supplied to the capacitor C602, thereby shortening the charging time. This indicates that the conduction time of the main switching element Q601 is shortened. As a result, the energy stored in the insulating transformer T601 is reduced, so that the output voltage Vo is lowered and the constant voltage operation is performed. The operation is reversed when the output voltage is low.

  FIG. 7 shows the waveform of each part in the RCC method. Vgs is the control terminal voltage of the main switching element Q601, Vds is the voltage between the current inflow terminal and current outflow terminal of the main switching element Q601, Id is the current flowing through the main switching element Q601, and VNs is generated in the secondary winding Ns. , Is is a current flowing through the secondary side rectifier diode D602, and VNb is a voltage generated in the auxiliary winding Nb. First, the on period of main switching element Q601 will be described. When the voltage is applied to the control terminal by the starting resistor and the potential of Vgs rises, the main switching element Q601 becomes conductive, and Id increases linearly with a positive slope with time, and energy is stored in the insulating transformer T601. The At this time, since the main switching element Q601 is in the conductive state, Vds is almost zero, and VNs is applied to the secondary side rectifier diode and is reverse-biased, so Is does not flow. At this time, VNb indicates the voltage of the auxiliary winding Nb. When the capacitor is charged and the transistor becomes conductive, the control terminal voltage Vgs of the main switching element Q601 becomes zero and the main switching element Q601 becomes nonconductive, so that Id becomes zero and the gate source of the main switching element Q601 The inter-voltage Vgs is obtained by superimposing a voltage that is a winding ratio times the input voltage E and the secondary output voltage, and a surge voltage. At this time, the rectifier diode on the secondary side becomes conductive, and the energy accumulated in the insulating transformer T601 is transmitted to the secondary side. Is decreases linearly with a negative slope. At this time, since a negative voltage is generated in the auxiliary winding, the main switching element Q601 continues to be in a non-conducting state, and then energy transmission to the secondary side is completed, whereby the primary side inductance and the main switching of the isolation transformer T601 are completed. The oscillation of the element Q601 resonates and a voltage corresponding to the winding ratio is generated in the auxiliary winding Nb of the insulating transformer T601, whereby the main switching element is turned on again to continue the oscillation operation.

  By the above operation, when the device is operating and the load is large, control is performed so as to output a constant voltage with respect to the load fluctuation. At this time, the mode selection terminal provided in the microcontroller IC 603 sets the control terminal of the switching element Q603 to LOW. As a result, switching element Q603 does not become conductive, and main switching element Q601 is not forced to stop oscillating. On the other hand, when the equipment is inactive and the load is reduced, the mode selection terminal applies a pulse signal that repeats HIGH / LOW to the control terminal of the switching element Q603. During the period when the control terminal of the switching element Q603 is HIGH, a current limited by the resistor R612 flows through the secondary light emitting diode of the photocoupler IC601 regardless of the output of the differential amplifier IC602. This current is sufficiently larger than that during the operation of the device, and the current transmitted to the primary side phototransistor of the photocoupler IC 601 instantaneously increases the voltage of the capacitor C602, thereby bringing the switching element Q602 into a conductive state. Switching element Q601 is turned off. If this state is continued for about 2 to 20 times the oscillation frequency of the self-excited switching power supply, for example, all the energy of the insulating transformer T601 is released, and the primary side of the self-excited switching power supply is in the same state as before startup. Thereafter, as in the start-up operation, a voltage is applied to the control terminal by the start resistor R601 and the resistor R602, and a time delay determined by the time constant due to the capacitance between the start resistor R601 and the gate control terminal of the main switching element Q601 occurs. After that, the main switching element Q601 becomes conductive again. If the secondary load of the switching power supply is small, the output voltage can be maintained almost as it is. When the control terminal of the switching element Q603 returns from HIGH to LOW, the current of the light emitting diode on the secondary side of the photocoupler IC 601 is also almost restored to the previous state.

  As described above, by repeatedly inputting a HIGH / LOW signal to the control terminal of the switching element Q603, the number of oscillations per unit time of the self-excited switching power supply can be reduced. Loss can be reduced and higher efficiency can be achieved. Although a detailed circuit is not shown, V1 indicates a DC output voltage generated by stepping down Vo, and the microcontroller IC 603 operates by this V1.

(Behavioral behavior)
Specific examples are shown below. FIG. 8 shows a problematic operation. From the top, the operation mode of the device, the DC output voltage of the switching power supply, the gate-source voltage Vgs of the main switching element Q601, and the pulse output from the microcontroller are shown. . In the device operation mode, the switching power supply device oscillates continuously, the gate-source voltage Vgs has a continuous waveform, the pulse output from the microcontroller maintains the LOW level, and the DC output voltage is stable without fluctuation. is doing. On the other hand, in the device hibernation mode, a pulse-like signal that repeats HIGH / LOW is output from the microcontroller, and the switching power supply device is repeatedly forcibly stopped and started. At this time, if the power required for device operation is large, the DC power output voltage will drop between the forced stop and start-up of the switching power supply, and if it drops below the voltage that can maintain the device operation, the operation will stop. . In FIG. 8, t1 indicates the delay time from the pulse output from the microcontroller to the activation of the main switching element Q601. When this delay time is long, the drop in the DC output voltage occurs at a smaller load. become. On the other hand, when the load capacity determined by the circuit scale, operation and function of the equipment supplied with power from the switching power supply device is large, in order to avoid a drop in the DC output voltage, The resistance value of R601 is set small, the delay time determined by the time constant due to the capacitance between the starting resistor R601 and the gate control terminal of the main switching element Q601 is minimized, and the delay time until the main switching element Q601 is turned on is reduced. By shortening, a method of increasing the number of times of switching and securing load supply capability is taken.

  However, since all direct currents flowing through the starting resistors R601 and R602 become reactive currents, if the resistance value of the starting resistor R601 is set to be small, the reactive current increases and the efficiency of the switching power supply during device operation decreases. Resulting in. Although depending on the DC input voltage as an example, when the starting resistance R601 is set to about 100 kΩ when AC240V is input and the starting resistance R601 is set to about 1 MΩ, the reactive power is reduced when the gate control voltage is the same. It becomes 1.35W and 0.135W, and the input power becomes 1.2W or more.

In order to achieve the above object, the power supply device according to the first invention of the present application is:
A transformer having a primary winding, an auxiliary winding, and a secondary winding, one end of the primary winding of the transformer, and a high potential side of a DC power source generated from a commercial power source are connected, and the primary winding of the transformer A first switching element that is connected between the other end of the DC power source and the low potential side of the DC power source and controls a current flowing in the primary winding of the transformer, and an alternating voltage generated in the secondary winding Smoothing rectifying means for smoothing rectification, error detecting means for comparing the output voltage of the smoothing rectifying means with a reference voltage, and outputting a voltage corresponding to the difference, a primary side portion and a secondary side portion, and the error The first transmission means for transmitting the output of the detection means to the primary side, the conduction interruption of the current flowing through the first switching element by the feedback signal from the first transmission means and the feedback signal from the auxiliary winding And a control means for controlling the first switch. The control terminal of the switching element includes a first resistor connected between the high potential side and a second resistor connected between the control terminal of the first switching element and the low potential side. A current inflow terminal of a second switching element is connected to an output of the error detecting means, a current outflow terminal is connected to the low potential side, and a pulse signal is applied to a control terminal of the second switching element. Regardless of the output of the error detection means by providing, comprises a mode selection means for forcibly stopping the oscillation of the first switching element,
A photocoupler is used as a second transmission means having a primary side portion and a secondary side portion, and a series circuit of a third resistor and a phototransistor of the photocoupler is connected in parallel to the first resistor. In the power supply device in which the light emitting diode of the photocoupler is controlled to emit light according to the mode selection signal,
The mode selection means applies a pulse signal to a control terminal of the second switching element when the device supplied with power from the power supply device is in a standby state, and also applies the mode selection signal to the first device. Means for changing the starting time of the main switching element.

The power supply device according to the second invention of the present application is:
Means are provided for connecting a parallel circuit of a fourth resistor and a phototransistor of the photocoupler in series with the first resistor.

The power supply device according to the third invention of the present application is:
A pulse transformer having a primary side portion and a secondary side portion is used as the second transmission means, and a parallel circuit of a fifth resistor and a fourth switching element is connected in series with the first resistor. The fourth switching element is driven by the secondary output of the pulse transformer, and the primary side of the pulse transformer changes the starting time of the first main switching element by controlling the pulse drive by the mode selection signal. It has a means to make it.

As explained above, according to the power supply device of the first invention of the present application,
In addition to providing a switching power supply that can supply sufficient power during equipment sleep operation, it is possible to minimize the efficiency reduction of the switching power supply due to reactive power due to starting resistance during equipment operation. Become.

According to the power supply device of the second invention of the present application,
A photocoupler having a low withstand voltage between the current inflow terminal and the current outflow terminal can be used, and a start-up time setting circuit can be configured with less expensive elements.

According to the power supply device of the third invention of the present application,
A stable start-up time setting circuit that is not affected by temperature characteristics is configured by using a pulse transformer as a drive circuit instead of a photocoupler with large variations in current transfer rate and large changes in temperature and change with time. It becomes possible.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  FIG. 1 shows a circuit configuration of a switching power supply apparatus for explaining a first embodiment according to the present invention. The difference from the conventional example is that the resistor R101 and the light receiving side of the photocoupler IC101 are in parallel with the starting resistor R601. A series circuit of the phototransistor Q101 is connected, and the light emitting side diode D101 of the photocoupler IC101 has one end connected to the high potential side of the DC output voltage and the other end connected to the current inflow terminal of the switching element Q102 via the resistor R102. The current outflow terminal of the element Q102 is connected to the low potential side of the DC output voltage, the output signal P2 from the microcontroller IC 603 is input to the control terminal of the switching element Q102, and the resistance value of the starting resistor R601 is increased. There is a feature. Note that the operation of the switching power supply during device operation is the same as that of the conventional example, and thus the description thereof is omitted. FIG. 2 shows the state of each signal in each operation state of the switching power supply for explaining the present embodiment. As shown in FIG. 2, during the device operation mode, the main switching element Q601 continuously oscillates so as to be at the gate-source voltage Vgs. In the device inactive state, a HIGH / LOW intermittent signal is output to the output P1 from the microcontroller IC 603, and the forced stop operation and the start operation of the main switching element Q601 are repeated. The output P2 of the microcontroller IC 603 is at the LOW level in the device operation mode, and the switching element Q102 is turned off so that no current flows through the light emitting side diode D101 of the photocoupler IC101. As a result, the resistor R101 is disconnected from the starting resistor R601, so that the R601 is set large within a range in which the switching power supply can be started. Therefore, the reactive current flowing through the R601 and R602 is reduced, and the power consumption is reduced. Increases efficiency. On the other hand, the microcontroller IC 603 sets the output P2 to the HIGH level when the device is inactive, thereby bringing the switching element Q102 into a conducting state, passing a current through the light emitting side diode D101 of the photocoupler IC101, and conducting the light receiving side phototransistor Q101 of the photocoupler IC101. State. As a result, the resistor R101 is connected in parallel to the starting resistor R601, thereby increasing the gate-source voltage of the main switching element Q601 and thereby increasing the starting time after the forced stop operation by the microcontroller IC603. With this operation, it is possible to freely change the load supply capability of the switching power supply apparatus when the device is inactive by setting the resistor R101. Generally, the load power required for a switching power supply when the equipment is inactive may be small. However, due to the recent trend toward lower voltage, the operating current of the equipment tends to increase. Depending on the circuit scale, the required load power can be supplied when the equipment is inactive. In many cases, the increase in reactive power during device operation and the load supply capability during device outage were in a trade-off relationship. According to the present embodiment, it is possible to provide a switching power supply device that can suppress an increase in reactive power during device operation and can secure a load supply capability necessary when the device is stopped. In this embodiment, a microcomputer is used as an example. However, it should be noted that the present invention is not limited to a microcontroller as long as mode selection is possible and pulse signal oscillation is possible. Further, as a circuit example showing a configuration of a self-excited switching power supply, a MOSFET is used as a main switching element. However, for example, when the main switching element is configured from a bipolar transistor, the configuration can be appropriately changed. . In the embodiment, the reference voltage is created by a Zener diode, but it should be clearly stated that the present invention is not limited to the means for creating the reference voltage.

  FIG. 3 shows a circuit configuration of a switching power supply device for explaining a second embodiment according to the present invention. The difference from the conventional example is that the resistor R301 and the light receiving side of the photocoupler IC301 are connected in series with the starting resistor R601. A parallel circuit of the phototransistor Q301 is connected, and the light emitting side diode D301 of the photocoupler IC301 has one end connected to the high potential side of the DC output voltage and the other end connected to the current inflow terminal of the switching element Q302 via the resistor R302. The current outflow terminal of the element Q302 is connected to the low potential side of the DC output voltage, and the output signal P2 from the microcontroller IC 603 is input to the control terminal of the switching element Q302 to increase the resistance value of the starting resistor R601. There is a feature. The output P2 of the microcontroller IC 603 is at the LOW level in the device operation mode, and the switching element Q302 is turned off so that no current flows through the light emitting side diode D301 of the photocoupler IC301. As a result, the resistor R301 is added in series with the starting resistors R601 and R602, so that the reactive current flowing through the R601 and R602 is reduced, thereby reducing the power consumption and thus the power supply efficiency. On the other hand, the microcontroller IC 603 sets the output P2 to the HIGH level when the device is inactive, thereby bringing the switching element Q302 into a conducting state, causing a current to flow through the light emitting side diode D301 of the photocoupler IC301, and conducting the light receiving side phototransistor Q301 of the photocoupler IC301. State. As a result, the resistor R301 is short-circuited, whereby the gate-source voltage of the main switching element Q601 is increased, and the startup time after the forced stop operation by the microcontroller IC 603 is advanced. Similar to the first embodiment, the load that can be supplied when the apparatus is stopped is increased by advancing the start-up time of the main switching element. This embodiment is largely different in that a resistor R301 is connected in parallel to the phototransistor Q301 of the photocoupler IC301. By connecting R301 in series to the starting resistor R601, the voltage applied to the phototransistor Q301 can be determined by this resistance value. Ultimately, the resistor R301 is set while balancing the load supply capability within the breakdown voltage range of the phototransistor Q301. However, as in the first embodiment, a startup time setting circuit is configured without using a high breakdown voltage element. There is a merit that becomes possible.

  FIG. 4 is a circuit configuration diagram of a switching power supply for explaining a third embodiment according to the present invention. The difference between the first embodiment and the second embodiment is that a pulse is used instead of a photocoupler as a transmission means. It is characterized by using a transformer T401. In this embodiment, a parallel circuit of a resistor R401 and a switching element Q401 is connected in series to the starting resistor R601, and the secondary of the pulse transformer T401 is connected between the control terminal of the switching element Q401 and the current outflow terminal via the resistor R402. Connected side. One end of the primary side of the pulse transformer T401 is connected to the high potential side of the DC output voltage, the other end is connected to the current inflow terminal of the switching element Q402, and the current outflow terminal of the switching element Q402 is the low potential of the DC output voltage. The output signal P2 from the microcontroller IC 603 is input to the control terminal of the switching element Q402 via the resistor R403. Between the primary side terminals of the pulse transformer T401, a diode D401 is connected as a regenerative current route so that the high potential side of the DC output voltage becomes the cathode.

  FIG. 5 shows the state of each signal in each operation state of the switching power supply for explaining the present embodiment. The difference between the first and second embodiments is that the pulse transformer T401 is driven by applying a pulse signal that repeats HIGH / LOW to the output signal P2 from the microcontroller IC603. The period for maintaining the HIGH level of the output signal P2 may be set to a time (t1) or longer until the switching power supply is activated. During the period in which the HIGH level is maintained, R401 is short-circuited, and a series circuit including only the starting resistors R601 and R602 is formed, the gate-source voltage of the main switching element Q601 is increased, and the starting time after the forced stop operation by the microcontroller IC 603 is advanced. Yes. This operation makes it possible to secure the necessary load supply capability by advancing the startup time of the switching power supply when the equipment is inactive. On the other hand, during the operation of the device, the output signal P2 from the microcontroller IC 603 is maintained at the LOW level to stop the driving of the pulse transformer T401, and the resistor R401 is added in series with the starting resistors R601 and R602 to generate the reactive current. It can be reduced. In addition, the use of the pulse transformer T401 has a large current transfer rate variation (about 100% to 400%), and the device variation is smaller than that of a photocoupler in which the temperature change and the time change of the current transfer rate are large. It is possible to configure a startup time setting circuit with little change and change with time.

The circuit block diagram for demonstrating the 1st Example of this invention. FIG. 3 is a state diagram of each signal for explaining the first embodiment of the present invention. The circuit block diagram for demonstrating the 2nd Example of this invention. The circuit block diagram for demonstrating the 3rd Example of this invention. FIG. 6 is a state diagram of each signal for explaining a third embodiment of the present invention. The circuit block diagram of the conventional switching power supply device. The operation | movement waveform diagram of each part for demonstrating a prior art example. The state diagram of each signal for demonstrating a prior art example.

Explanation of symbols

R101 Parallel resistor IC101 Photocoupler Q101 Phototransistor D101 Photodiode R301 Series resistor IC301 Photocoupler Q301 Phototransistor D301 Photodiode T401 Pulse transformer R401 Series resistor Q401 Switching element IC603 Mode selection means (microcontroller)

Claims (5)

A transformer having a primary winding, an auxiliary winding, and a secondary winding, one end of the primary winding of the transformer, and a high potential side of a DC power source generated from a commercial power source are connected, and the primary winding of the transformer A first switching element that is connected between the other end of the DC power source and the low potential side of the DC power source and controls a current flowing in the primary winding of the transformer, and an alternating voltage generated in the secondary winding Smoothing rectifying means for smoothing rectification, error detecting means for comparing the output voltage of the smoothing rectifying means with a reference voltage, and outputting a voltage corresponding to the difference, a primary side portion and a secondary side portion, and the error The first transmission means for transmitting the output of the detection means to the primary side, the conduction interruption of the current flowing through the first switching element by the feedback signal from the first transmission means and the feedback signal from the auxiliary winding And a control means for controlling the first switch. The control terminal of the switching element includes a first resistor connected between the high potential side and a second resistor connected between the control terminal of the first switching element and the low potential side. Prepared,
The output of the error detection means is connected to the current inflow terminal of the second switching element, the current outflow terminal is connected to the low potential side, and a pulse signal is given to the control terminal of the second switching element. Thus, regardless of the output of the error detection means, in the power supply apparatus comprising the mode selection means for forcibly stopping the oscillation of the first switching element,
Start-up time setting means for changing the start-up time of the first main switching element through second transmission means having a primary side portion and a secondary side portion in response to a mode selection signal from the mode selection means. A power supply device comprising:   The first and second transmission means are photocouplers whose primary side is a phototransistor and whose secondary side is a light emitting diode, and the start-up time setting means is connected in parallel to the first resistor. 2. A series circuit of a third resistor and a phototransistor of the second transmission means, wherein the light emitting diode of the second transmission means is controlled to emit light according to the mode selection signal. The power supply device described in 1.   The first and second transmission means are photocouplers whose primary side is a phototransistor and whose secondary side is a light-emitting diode, and the start-up time setting means is connected in series to the first resistor. 2. A parallel circuit of a fifth resistor and a phototransistor of the second transmission means, wherein the light emitting diode of the second transmission means is controlled to emit light according to the mode selection signal. The power supply device described in 1.   The first transmission means is a photocoupler having a primary side made of a phototransistor and a secondary side made of a light emitting diode, and the second transmission means is a pulse transformer having a primary side portion and a secondary side portion. The start-up time setting means is a parallel circuit of a sixth resistor and a fourth switching element connected in series with the first resistor, and a fourth switching element is generated by a secondary side output of the pulse transformer. 2. The power supply device according to claim 1, wherein the first side of the pulse transformer is pulse-driven controlled by the mode selection signal.   The mode selection means applies a pulse signal to the control terminal of the second switching element when the device to which power is supplied from the power supply device is in a device inactive state, and applies the mode selection signal to activate the device. The power supply device according to any one of claims 1 to 4, wherein the startup time of the first main switching element is advanced via a time setting means.

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