JP6556909B2 - Control circuit and switching power supply - Google Patents

Description

  The present invention relates to a control circuit for a switching power supply and a switching power supply.

  In the field of switching power supplies used in electrical equipment such as lighting devices, there is an increasing demand for low power consumption in a standby mode in which the load of the switching power supply is very small. In order to reduce the power consumption in the standby mode, it is necessary to reduce the power consumption of the control circuit for controlling the switching power supply and the control power supply circuit supplied to the control circuit. As a technique for reducing the power consumption of the control power supply circuit, for example, there is an invention disclosed in Patent Document 1.

  In the invention disclosed in Patent Document 1, a control power supply circuit that supplies a control power supply Vcc to a first control circuit for controlling the oscillation operation of the switching power supply is provided, and a semiconductor switch is connected from the DC power supply Vdc of the switching power supply. A control power supply Vcc is supplied through the element. In the invention disclosed in Patent Document 1, each semiconductor switch element is linked with an operation mode control circuit 5 that controls an operation state including a load start mode, a steady operation mode, and a protection mode when a load is abnormal. Control operation according to the mode is performed.

  According to the invention disclosed in Patent Document 1, loss in the control power supply circuit can be reduced, and the control power supply during operation is not affected by the state of the lamp load or unstable transient operation during startup. , Can be supplied stably.

  If such a control power supply circuit and a control circuit are formed as a semiconductor integrated circuit formed on a predetermined semiconductor substrate and the semiconductor integrated circuit is mounted on a predetermined module, the switching power supply can be easily designed. This is advantageous in that the electrical equipment such as an illumination lighting device can be miniaturized.

  By the way, when configuring the semiconductor integrated circuit as described above, in order to generate a reference voltage (for example, 5 V) and a gate drive voltage (for example, 15 V) for driving the switching element of the switching circuit in the semiconductor integrated circuit, It is necessary to stably supply control power to the inside of the semiconductor integrated circuit.

  Therefore, conventionally, as described above, in order to supply the control power supply Vcc from the DC power supply Vdc of the switching power supply via the semiconductor switch element, a starter circuit that directly drops the DC power supply Vdc of the switching power supply is built in the control circuit. Are equal.

JP 2011-243335 A

However, since the DC power supply Vdc of the switching power supply is a high voltage, and the starter circuit is configured by a so-called dropper circuit, the power P expressed by the following equation is always the starter circuit during the operation of the control circuit. It will be consumed.
P = (Vdc−Vcc) × Icc (1)

  Here, P is the power consumed by the startup circuit, Vdc is the voltage input to the startup circuit, Vcc is the voltage output from the startup circuit, and Icc is the current flowing from the DC power supply Vdc to the control circuit via the dropper circuit. Represent.

  In the formula (1), for example, when Vdc = 339 V, Vcc = 15 V, and Icc = 3 mA, P = 0.97 W, but such power consumption is a reduction in power consumption during standby of electronic devices and the like. There was a problem that hindered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control circuit for a switching power supply that can reduce standby power.

  The present invention proposes the following matters in order to solve the above problems.

A control circuit used for switching control of a switching power supply comprising: a rectifying unit that rectifies input alternating current and outputs direct current; and a smoothing unit that smoothes direct current rectified by the rectifying unit,
An activation power supply unit having a switch, receiving control power necessary for the switching control via the switch, and starting activation of the switching control;
The first detection point voltage, which is the difference between the potential at the first detection point where the potential changes in accordance with the input AC phase and the reference potential at the reference point of the switching power supply, and the second smoothed by the smoothing unit. A voltage detection unit that detects at least one or both of the second detection point voltage, which is the difference between the potential of the detection point and the reference potential;
A startup power supply control unit that controls the operation of the startup power supply unit based on the first detection point voltage or the first detection point voltage and the second detection point voltage;
A control circuit characterized by comprising:

  The starting power supply control unit controls the starting power supply unit to turn on the switch and receive control power when the first detection point voltage is lower than the predetermined first reference voltage, and the first detection point voltage is set to the first reference voltage. There has been proposed a control circuit characterized by controlling the start-up power supply unit so as not to receive control power by turning off the switch when the voltage is higher than the voltage.

  The starting power supply control unit controls the starting power supply unit to turn on the switch and receive control power when the second detection point voltage is lower than a predetermined second reference voltage, and the second detection point voltage is set to the second reference voltage. If the voltage is equal to or higher than the voltage and the first detection point voltage is less than the first reference voltage, the switch is turned on to control the start-up power supply unit to receive the control power, and the second detection point voltage is higher than the second reference voltage. There is also proposed a control circuit characterized in that when the first detection point voltage is equal to or higher than the first reference voltage, the start power supply unit is controlled so as not to receive the control power by turning off the switch.

  A control circuit has been proposed in which the on-time of the switch is controlled to a predetermined time by setting a first reference voltage corresponding to the input AC voltage.

  A control circuit is proposed in which the first reference voltage is set corresponding to the second detection point voltage.

  A control circuit is proposed in which the first reference voltage is set in direct proportion to the second detection point voltage.

  A control circuit is proposed in which the first detection point is provided on the input side of the rectification unit.

The switching power supply has a first switching element, and includes a power factor correction circuit unit that improves the power factor of the switching power supply by the switching operation of the first switching element.
A power factor correction circuit control unit that monitors the voltage input to the power factor correction circuit unit by detecting the first detection point voltage and controls the switching of the first switching element based on the first detection point voltage is provided. A control circuit characterized by this is proposed.

  The power factor correction circuit control unit has proposed a control circuit characterized by performing constant voltage control on the output voltage of the power factor correction circuit unit by detecting the second detection point voltage.

The switching power supply includes a step-down chopper circuit unit that has a second switching element and steps down and outputs the output voltage of the power factor correction circuit unit by a switching operation of the second switching element.
A control circuit including a step-down chopper circuit control unit that controls switching of the second switching element is proposed.

  The step-down chopper circuit control unit proposes a control circuit characterized by performing constant current control on the output current of the step-down chopper circuit unit by detecting the output current of the step-down chopper circuit unit.

  The control circuit has been proposed as a control circuit formed as a semiconductor integrated circuit on a predetermined semiconductor substrate.

The semiconductor integrated circuit is mounted on a predetermined module having a first detection point voltage terminal for detecting a first detection point voltage,
The first detection point voltage terminal is connected to the voltage detection unit and the power factor correction circuit control unit, the voltage detection unit detects the first detection point voltage via the first detection point voltage terminal, and the power factor A control circuit is proposed in which the improvement circuit control unit monitors the voltage input to the power factor correction circuit unit.

  According to the present invention, the startup power supply unit receives the control power necessary for the switching control via the switch and starts to start the switching control operation, and the voltage detection unit has a potential corresponding to the input AC phase. The first detection point voltage, which is the difference between the potential of the first detection point where the voltage changes and the reference potential of the reference point of the switching power supply, and the difference between the potential of the second detection point smoothed by the smoothing unit and the reference potential At least one or both of the second detection point voltages are detected, and the start-up power supply control unit controls the start-up power supply based on the first detection point voltage or the first detection point voltage and the second detection point voltage. Control the operation of the unit. Accordingly, control power can be stably supplied to the control circuit, and standby power can be reduced.

  According to the present invention, when the first detection point voltage is less than the predetermined first reference voltage, the startup power supply control unit controls the startup power supply unit to turn on the switch and receive the control power, and to detect the first detection point voltage. When the point voltage is equal to or higher than the first reference voltage, the start power supply unit is controlled so as not to receive the control power by turning off the switch. Accordingly, control power can be stably supplied to the control circuit, and standby power can be reduced.

  According to the present invention, when the second detection point voltage is lower than the predetermined second reference voltage, the startup power supply control unit controls the startup power supply unit to turn on the switch and receive the control power, and to detect the second detection point voltage. When the point voltage is equal to or higher than the second reference voltage and the first detection point voltage is lower than the first reference voltage, the start power supply unit is controlled to receive the control power by turning on the switch, and the second detection point voltage is When the voltage is equal to or higher than the second reference voltage and the first detection point voltage is equal to or higher than the first reference voltage, the activation power supply unit is controlled not to receive the control power by turning off the switch. Therefore, when the input AC voltage is less than the predetermined voltage, the control power is stably supplied to the control circuit, and when the input AC voltage is the predetermined voltage or more, the standby power can be reduced. Can be planned.

  According to the present invention, the ON time of the switch is controlled to a predetermined time by setting the first reference voltage corresponding to the input AC voltage. Therefore, even when the AC voltage input to the switching power supply fluctuates, control power can be stably supplied to the control circuit, and standby power can be reduced.

  According to the present invention, the first reference voltage is set corresponding to the second detection point voltage. Therefore, when the AC voltage input to the switching power supply varies, the second detection point voltage varies corresponding to the AC voltage variation, and the first reference voltage corresponds to the second detection point voltage variation. Is set. Therefore, even when the AC voltage input to the switching power supply fluctuates, control power can be stably supplied to the control circuit, and standby power can be reduced.

  According to the present invention, the first reference voltage is set in direct proportion to the second detection point voltage. Therefore, when the AC voltage input to the switching power supply fluctuates, the second detection point voltage fluctuates corresponding to the AC voltage fluctuation, and the second detection point voltage fluctuates in direct proportion to the second detection point voltage fluctuation. One reference voltage is set. Therefore, even when the AC voltage input to the switching power supply fluctuates, control power can be stably supplied to the control circuit, and standby power can be reduced.

  According to the present invention, the first detection point is provided on the input side of the rectification unit. Therefore, it is possible to accurately detect information on the AC voltage input to the switching power supply, to reliably supply control power to the control circuit, and to reduce standby power.

  According to the present invention, the switching power supply includes the first switching element, and includes the power factor correction circuit unit that improves the power factor of the switching power supply by the switching operation of the first switching element. The voltage input to the power factor correction circuit unit is monitored by detecting the first detection point voltage, and the switching of the first switching element is controlled based on the first detection point voltage. Therefore, it is not necessary to separately provide a circuit for detecting the input voltage of the power factor correction circuit unit, and the configuration of the switching power supply can be simplified. Further, when the control circuit is a semiconductor integrated circuit formed on a predetermined semiconductor substrate and this semiconductor integrated circuit is mounted on a predetermined module, a terminal for detecting the input voltage of the power factor correction circuit unit is provided. There is no need to provide it separately, and the configuration of the control circuit and the switching power supply can be simplified.

  According to the present invention, the power factor correction circuit control unit performs constant voltage control on the output voltage of the power factor correction circuit unit by detecting the second detection point voltage. Therefore, it is not necessary to separately provide a circuit for detecting the output voltage of the power factor correction circuit unit, and the configuration of the switching power supply can be simplified. Further, when the control circuit is a semiconductor integrated circuit formed on a predetermined semiconductor substrate and this semiconductor integrated circuit is mounted on a predetermined module, a terminal for detecting the output voltage of the power factor correction circuit unit is provided. There is no need to provide it separately, and the configuration of the control circuit and the switching power supply can be simplified.

  According to the present invention, the switching power supply includes the step-down chopper circuit unit, and the step-down chopper circuit unit steps down and outputs the output voltage of the power factor correction circuit unit by the switching operation of the second switching element. Therefore, the switching power supply can be configured as a power supply for various applications.

  According to the present invention, the step-down chopper circuit control unit detects the output current of the step-down chopper circuit unit, and outputs the output current of the step-down chopper circuit unit under constant current control. Therefore, a switching power supply suitable for a load such as LED lighting that requires constant current control can be configured.

  According to the present invention, since the control circuit is configured as a semiconductor integrated circuit on a predetermined semiconductor substrate, the configuration of the control circuit and the switching power supply can be simplified.

  According to the present invention, the semiconductor integrated circuit is mounted on a predetermined module having a first detection point voltage terminal for detecting the first detection point voltage, and the first detection point voltage terminal includes the voltage detection unit and the power factor correction circuit. The voltage connected to the control unit, the voltage detection unit detects the first detection point voltage via the first detection point voltage terminal, and the power factor improvement circuit control unit inputs the voltage input to the power factor improvement circuit unit. Since it is configured to monitor, it is necessary to separately provide a terminal for the voltage detection unit to detect the first detection point voltage and a terminal for the power factor improvement circuit control unit to monitor the voltage input to the power factor improvement circuit unit. The number of terminals of the module can be reduced.

It is a circuit diagram which shows the structure of the switching power supply 1 using the control circuit which concerns on embodiment of this invention. It is a block circuit diagram which shows the structure of the control circuit 30 which concerns on embodiment of this invention. FIG. 3 is a block circuit diagram illustrating an example of a configuration of a startup power supply unit 100 in FIG. 2. FIG. 3 is a block circuit diagram illustrating a configuration example of a voltage detection unit 210 as an example of the voltage detection unit 200 in FIG. 2. FIG. 3 is a block circuit diagram illustrating a configuration example of a voltage detection unit 230 as an example of the voltage detection unit 200 in FIG. 2. FIG. 3 is a block circuit diagram illustrating a configuration example of a voltage detection unit 250 as an example of the voltage detection unit 200 in FIG. 2. FIG. 3 is a block circuit diagram showing an example of a configuration of a startup power supply control unit 300 in FIG. 2. FIG. 4 is a waveform diagram of a first detection point voltage Vd1, a switch current I102, a signal S1, a signal S2, a signal S3, and a signal S4 according to the first embodiment of the present invention. Waveform diagrams of the first detection point voltage Vd1, the second detection point voltage Vd2, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the second embodiment of the present invention (input AC voltage Vin = AC100V Example of conditions). Waveform diagrams of the first detection point voltage Vd1, the second detection point voltage Vd2, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the second embodiment of the present invention (input AC voltage Vin = AC200V) Example of conditions). Waveform diagrams of the first detection point voltage Vd1, the second detection point voltage Vd2, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the third embodiment of the present invention (input AC voltage Vin = AC100V and An example of the condition of input AC voltage Vin = AC200V).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations in combination with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

(First embodiment)
FIG. 1 is a circuit diagram showing a configuration of a switching power supply 1 according to an embodiment of the present invention. FIG. 2 is a block circuit diagram showing a configuration of the control circuit 30 according to the embodiment of the present invention. FIG. 3 is a block circuit diagram showing an example of the configuration of the startup power supply unit 100 in FIG. FIG. 4 is a block circuit diagram illustrating a configuration example of a voltage detection unit 210 as an example of the voltage detection unit 200 in FIG.

  FIG. 7 is a block circuit diagram showing an example of the configuration of the startup power supply control unit 300 in FIG. FIG. 8 is a waveform diagram of the first detection point voltage Vd1, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the first embodiment of the present invention.

  The switching power supply 1 according to the present embodiment includes a rectifying unit 10, a smoothing unit 20, a control circuit 30, a power factor correction circuit unit 80, and a step-down chopper circuit unit 90. The rectifying unit 10 is connected to the AC power source 2 on the input side, rectifies the input AC and outputs DC.

  The smoothing unit 20 is connected to the output side of the rectifying unit 10 and smoothes the direct current rectified by the rectifying unit 10. The rectifying unit 10 uses, for example, a bridge diode configured by bridge-connecting the diodes 11 to 14, and the smoothing unit 20 is configured using, for example, a capacitor 21.

  In addition, the switching power supply 1 includes, for example, a steady mode in which a microcomputer 5 is connected via a control circuit 30 and operates at a steady load according to a control signal output from the microcomputer 5 to the control circuit 30, and a standby mode for a minute load. The configuration can be switched between.

  In the standby mode, the power factor correction circuit unit 80 and the step-down chopper circuit unit 90 are controlled not to perform a switching operation. In the steady mode, the power factor correction circuit unit 80 and the step-down chopper circuit unit 90 are controlled to perform a switching operation.

  The power factor improving circuit unit 80 includes a switching element 81 and the like, and is provided between the rectifying unit 10 and the smoothing unit 20 on the output side of the rectifying unit 10, and by switching the switching element 81, The voltage output from the rectifying unit 10 is boosted and output to the smoothing unit 20.

  The step-down chopper circuit unit 90 includes a switching element 91 and the like, provided on the output side of the power factor correction circuit unit 80 and connected to the smoothing unit 20, and switching the switching element 91 allows the voltage of the smoothing unit 20 to be switched. Is supplied to the load 70 such as an LED.

  The control circuit 30 performs switching control of the switching power supply 1 including the power factor correction circuit unit 80, the step-down chopper circuit unit 90, and the like. As shown in FIG. 2, the control circuit 30 includes a startup power supply unit 100, a voltage detection unit 200, a startup power supply control unit 300, a stop circuit 400, a UVLO 600, a power factor correction circuit control unit 800, and a step-down chopper. A circuit control unit 900.

  Note that it is preferable to configure the control circuit 30 as a semiconductor integrated circuit formed on a predetermined semiconductor substrate in that the configuration of the control circuit 30 and the switching power supply 1 can be simplified.

  In this case, the semiconductor substrate is mounted on a predetermined module having a first detection point voltage terminal (corresponding to the MULTI terminal in FIGS. 1 and 2) for detecting the first detection point voltage, and the first detection point voltage terminal is The voltage detection unit 200 and the power factor correction circuit control unit 800 are connected to each other, and the voltage detection unit 200 detects the first detection point voltage Vd1 via the first detection point voltage terminal. However, when the voltage input to the power factor correction circuit unit 80 is monitored, a module having a small number of terminals can be configured.

  The startup power supply unit 100 is connected to, for example, a positive end 21 a of the capacitor 21 located on the output side of the rectifying unit 10 and one end of a resistor 106 described later via the VDC terminal of the control circuit 30.

  The starting power supply unit 100 is connected to the auxiliary winding power supply 95 via the Vcc terminal of the control circuit 30. Further, the startup power supply unit 100 is connected to the power supply startup control unit 300, and the operation of the startup power supply unit 100 is controlled by the power supply startup control unit 300. The startup power supply unit 100 is controlled by, for example, a signal S3 and a signal S4 output from the power supply startup control unit 300.

  For example, as shown in FIG. 3, the startup power supply unit 100 includes a switch 101, a low breakdown voltage switch 102, a low breakdown voltage switch 103, a resistor 104, a resistor 105, a resistor 106, a Zener diode 107, a Zener diode 108, a diode 109, and a diode 110. In addition, the dropper circuit 120 can be combined.

  The switch 101 has a drain end, a source end, and a gate end. The drain end of the switch 101 is connected to, for example, the positive end 21 a of the capacitor 21 and one end of the resistor 106 located on the output side of the rectifying unit 10 via the VDC terminal of the control circuit 30.

  The source end of the switch 101 is connected to one end of the resistor 104. The gate end of the switch 101 is connected to the other end of the resistor 106, the cathode end of the Zener diode 107, and the anode end of the diode 109. For example, the switch 101 is turned on when the voltage between the terminals of the capacitor 21 becomes equal to or higher than a predetermined voltage. However, if the low breakdown voltage switches 102 and 103 are not turned on, no current flows through the switch 101.

  The low withstand voltage switch 102 is a switch having a control end, and is turned on when a low level signal S3 is input to the control end, and is turned off when a high level signal S3 is input to the control end. The control terminal of the low withstand voltage switch 102 is connected to the output terminal of the NOT gate 301 of the startup power supply control unit 300.

  One end of the low withstand voltage switch 102 other than the control end is connected to the anode end of the Zener diode 108, the cathode end of the diode 110, and the input end 120 a of the dropper circuit 120. The other end of the low withstand voltage switch 102 other than the control end is connected to the other end of the resistor 105.

  The low withstand voltage switch 103 is a switch having a control terminal, and is turned on when a high level signal S4 is input to the control terminal, and is turned off when a low level signal S4 is input to the control terminal. The control terminal of the low withstand voltage switch 103 is connected to the output terminal of the negative OR gate 303 of the startup power supply control unit 300.

  One end of the low withstand voltage switch 103 other than the control end is connected to the anode end of the diode 110 and the Vcc terminal of the control circuit 30. The other end of the low withstand voltage switch 103 other than the control end is connected to the other end of the resistor 104 and one end of the resistor 105.

  One end of the resistor 104 is connected to the source end of the switch 101. The other end of the resistor 104 is connected to the other end other than one end of the resistor 105 and the control end of the low withstand voltage switch 103.

  One end of the resistor 105 is connected to the other end other than the other end of the resistor 104 and the control end of the low withstand voltage switch 103. The other end of the resistor 105 is connected to the other end other than the control end of the low withstand voltage switch 102.

  One end of the resistor 106 is connected to the drain end of the switch 101, and is connected to the positive end 21 a of the capacitor 21 located on the output side of the rectifying unit 10, for example, via the VDC terminal of the control circuit 30. The other end of the resistor 106 is connected to the gate end of the switch 101, the cathode end of the Zener diode 107, and the anode end of the diode 109.

  The cathode end of the Zener diode 107 is connected to the gate end of the switch 101, the other end of the resistor 106, and the anode end of the diode 109. The anode end of the Zener diode 107 is connected to a GND terminal (not shown) of the control circuit 30 (a point having the same potential as the reference point 50).

  The cathode end of the Zener diode 108 is connected to the cathode end of the diode 109. The anode end of the Zener diode 108 is connected to one end other than the control end of the low withstand voltage switch 102, the cathode end of the diode 110, and the input end 120 a of the dropper circuit 120.

  The cathode end of the diode 109 is connected to the cathode end of the Zener diode 108. The anode end of the diode 109 is connected to the gate end of the switch 101, the other end of the resistor 106, and the cathode end of the Zener diode 107.

  The cathode end of the diode 110 is connected to the anode end of the Zener diode 108, one end other than the control end of the low breakdown voltage switch 102, and the input end 120 a of the dropper circuit 120. The anode end of the diode 110 is connected to one end other than the control end of the low withstand voltage switch 103 and the Vcc terminal of the control circuit 30.

  The dropper circuit 120 steps down the input voltage to a predetermined voltage and outputs it. The input end 120 a of the dropper circuit 120 is connected to one end other than the cathode end of the diode 110, the anode end of the Zener diode 108, and the control end of the low withstand voltage switch 102. A control power supply voltage Vst (for example, 5 V) is generated at the output terminal 120 b of the dropper circuit 120.

  The startup power supply unit 100 receives control power necessary for switching control from the output side of the rectifying unit 10 (for example, the positive end of the capacitor 21) via the switch 101, the low withstand voltage switch 102, and the like, and performs switching control of the switching power supply 1. Start the operation. The operation of the startup power supply unit 100 is controlled by the power supply startup control unit 300.

  The start-up power supply unit 100 receives control power from, for example, the output side of the rectifying unit 10 and starts to start the switching control operation of the switching power supply 1 in the start-up mode (the mode when the input power supply 2 is turned on) and the standby mode. Let In this case, a current I102 flows from the output side of the rectifier 10 to the switch 101, the resistor 104, the resistor 105, the low breakdown voltage switch 102, and the dropper circuit 120 via the VDC terminal of the control circuit 30.

  As described above, in FIG. 1, the VDC terminal of the control circuit 30 is connected to the positive terminal 21 a of the capacitor 21 located on the output side of the rectifying unit 10, but the positive terminal that is the output terminal of the rectifying unit 10. It is good also as a structure connected to the point which can receive control electric power, such as extreme 10c.

  Thus, when the current I102 flows, the control power is supplied to the control circuit 30, and the control power supply voltage Vst is generated. In the start-up mode and the standby mode, for example, the low breakdown voltage switch 102 is on / off controlled and the low breakdown voltage switch 103 is controlled to be in an off state.

  In the steady mode, for example, the control power is supplied to the control circuit 30 by the power supply from the auxiliary winding power supply 95, and the control power supply voltage Vst is generated. In the steady mode, the power supply voltage Vcc is also generated at the Vcc terminal of the control circuit 30. When the power supply from the auxiliary winding power supply 95 is insufficient in the steady mode, for example, the switch 101, the resistor 104, the low withstand voltage switch 103, the diode 110, and the like are connected from the output side of the rectifier 10 via the VDC terminal of the control circuit 30. It may be configured such that the control power is supplied to the control circuit 30 by causing the current I103 to flow through the dropper circuit 120 and the control power supply voltage Vst is generated.

  In this embodiment, an example is shown in which the step-down chopper circuit unit 90 of the switching power supply 1 includes the auxiliary winding power supply 95. However, in a switching power supply having a configuration that does not correspond to the auxiliary winding power supply 95, In the mode, the current I103 may be always supplied from the output side of the rectifier 10 to the switch 101, the resistor 104, the low breakdown voltage switch 103, the diode 110, and the dropper circuit 120 via the VDC terminal of the control circuit 30.

  In this embodiment, in the steady mode, for example, the low breakdown voltage switch 102 is controlled to be turned off. However, the low breakdown voltage switch 102 may be controlled to be turned on or off in the steady mode.

  The voltage detection unit 200 includes a first detection point voltage Vd1, which is a difference between the potential of the first detection point 40 where the potential changes in accordance with the input AC phase and the reference potential of the reference point 50 of the switching power supply 1. Then, at least one or both of the second detection point voltage Vd2 that is the difference between the potential of the second detection point 60 smoothed by the smoothing unit 20 and the reference potential is detected.

  It is desirable to provide the first detection point 40 on the input side of the rectifying unit 10 that is suitable as a position where the potential changes corresponding to the input AC phase. For example, two diodes 41 and 42 whose anodes are connected to the input terminals 10 a and 10 b of the rectifying unit 10 and whose cathodes are connected to each other are provided, and between the cathodes of the diodes 41 and 42 and the reference point 50. A resistor 43 and a resistor 44 connected in series are provided, and a connection point between the resistor 43 and the resistor 44 is defined as a first detection point 40.

  As described above, when the first detection point 40 is provided on the input side of the rectifying unit 10, the first detection point voltage Vd1 can be detected accurately and stably. The first detection point 40 may be a position where the potential changes in accordance with the input alternating current phase. For example, the output voltage of the rectifying unit 10 (voltage between the positive terminal 10c and the negative terminal 10d) is used. You may make it detect by dividing pressure.

  The second detection point 60 is preferably provided at a position where the voltage of the smoothing unit 20 is detected on the output side of the rectifying unit 10. For example, on the output side of the power factor correction circuit unit 80, a series circuit including a resistor 63 and a resistor 64 is formed in parallel with the smoothing unit 20, and a connection point between the resistor 63 and the resistor 64 is set as the second detection point 60.

  As described above, when the second detection point 60 is provided at a position where the voltage of the smoothing unit 20 is detected, the second detection point voltage Vd2 can be detected accurately and stably. Note that, as described above, the standby mode is controlled so that the power factor correction circuit unit 80 does not perform the switching operation. Therefore, the second detection point voltage Vd2 that is the voltage across the resistor 64 is a full-wave input AC. The rectified and smoothed voltage becomes a voltage divided by the resistor 63 and the resistor 64.

  That is, in the standby mode, the boosting operation by the power factor correction circuit unit 80 is not performed, and the input AC is subjected to full-wave rectification and smoothed voltage is applied to the smoothing unit 20, so the second detection point voltage Vd2 is The input AC voltage information and phase information are included.

  The first detection point 40 is connected to the MULTI terminal of the control circuit 30, and the second detection point 60 is connected to the VFB terminal of the control circuit 30. With such a configuration, a circuit for detecting the first detection point voltage Vd1, the second detection point voltage Vd2, the input voltage of the power factor correction circuit unit 80, and the output voltage of the power factor improvement circuit unit 80 is separately provided. Since it is not necessary to provide them independently, the configuration of the control circuit and the switching power supply can be simplified.

  Further, with the above configuration, when the control circuit 30 is a semiconductor integrated circuit formed on a predetermined semiconductor substrate and the semiconductor integrated circuit is mounted on a predetermined module, the voltage detection unit 200 is There is no need to separately provide a terminal for detecting the first detection point voltage Vd1 and a terminal for monitoring the voltage input to the power factor correction circuit unit by the power factor correction circuit control unit, thereby reducing the number of terminals of the module. be able to.

  The voltage detection unit 200 is connected to the first detection point 40 via the MULTI terminal of the control circuit 30. Further, the voltage detection unit 200 is connected to the second detection point 60 via the VFB terminal of the control circuit 30. Further, the voltage detection unit 200 is connected to the stop circuit 400 and the power factor correction circuit control unit 800.

  In addition, the voltage detection unit 200 is connected to the power supply activation control unit 300. The voltage detection unit 200 outputs a signal S2 to the power supply activation control unit 300. The power supply activation control unit 300 corresponds to the signal S2, and the first detection point voltage Vd1 or the first detection point voltage Vd1 and the second detection point are detected. The operation of the startup power supply unit 100 is controlled based on at least one or both of the point voltages Vd2.

  In the first embodiment, the voltage detection unit 200 has, for example, a configuration in which a comparator 211, a negative OR gate 212, and a first reference voltage power supply unit 213 are combined as shown in the voltage detection unit 210 of FIG. .

  The comparator 211 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the comparator 211 is connected to the first detection point 40 via the MULTI terminal of the control circuit 30.

  The inverting input terminal of the comparator 211 is connected to the reference voltage output terminal 213 b of the first reference voltage power supply unit 213. The output terminal of the comparator 211 is connected to one input terminal of the NOR circuit 212.

  The comparator 211 outputs a low level signal from the output terminal when the voltage at the MULTI terminal of the control circuit 30 is less than a predetermined first reference voltage Vth1 generated by the first reference voltage power supply unit 213. The comparator 211 outputs a high level signal from the output terminal when the voltage at the MULTI terminal of the control circuit 30 is equal to or higher than a predetermined first reference voltage Vth1 generated by the first reference voltage power supply unit 213.

  The NOR circuit 212 has two input terminals and an output terminal. One input terminal of the negative OR gate 212 is connected to the output terminal of the comparator 211. The other input terminal of the negative OR gate 212 is connected to the output terminal of the stop circuit 400. The output terminal of the NOR gate 212 is connected to the input terminal of the NOT gate 301 in the startup power supply control unit 300.

  The first reference voltage power supply unit 213 has an input terminal 213a and a reference voltage output terminal 213b. The input terminal 213 a of the first reference voltage power supply unit 213 is connected to the output terminal 120 b of the dropper circuit 120 in the startup power supply unit 100.

  The reference voltage output terminal 213 b of the first reference voltage power supply unit 213 is connected to the inverting input terminal of the comparator 211. The reference voltage output terminal 213b of the first reference voltage power supply unit 213 is configured to generate a predetermined first reference voltage Vth1.

  For example, the voltage detection unit 210 detects the first detection point voltage Vd1 when the signal S1 output from the stop circuit 400 is at a low level (standby mode).

  In the standby mode (when the level of the signal S1 input to the negative OR gate 212 is the low level), the voltage detection unit 210 is in the case where the first detection point voltage Vd1 is less than the predetermined first reference voltage Vth1 (comparison). For example, when the level of the output terminal of the device 211 is low level, a high-level signal S2 is output from the output terminal of the NOR circuit 212 (T1 in FIG. 8).

  The voltage detection unit 210 is in a standby mode (when the level of the signal S1 input to the negative OR gate 212 is low), and the first detection point voltage Vd1 is equal to or higher than a predetermined first reference voltage Vth1. In this case (when the level of the output terminal of the comparator 211 is High level), for example, a Low level signal S2 is output (T2 in FIG. 8).

  The startup power supply control unit 300 is connected to the power supply startup unit 100, the voltage detection unit 200, the stop circuit unit 400, and the UVLO 600. The startup power supply controller 300 controls the operation of the startup power supply unit 100 based on the first detection point voltage Vd1 or the first detection point voltage Vd1 and the second detection point voltage Vd2.

  For example, in the first embodiment, the startup power supply control unit 300 corresponds to the signal S2 output from the voltage detection unit 200 (the voltage detection unit 210 in the first embodiment) based on the first detection point voltage Vd1. Then, the signal S3 is output to the startup power supply unit 100 to control the operation of the startup power supply unit 100.

  In addition, startup power supply control unit 300 outputs signal S4 to startup power supply unit 100 in response to signal S1 output from stop circuit 400 and signal S0 output from UVLO 600, and controls the operation of startup power supply unit 100.

  In the present embodiment, the startup power supply control unit 300 is configured by combining a NOT gate 301, a NOT gate 302, and a NOT OR gate 303, for example, as shown in FIG.

  The NOT gate 301 has an input end and an output end. The input terminal of the NOT gate 301 is connected to the output terminal of the negative OR gate 212 of the voltage detection unit 210. The output terminal of the NOT gate 301 is connected to the control terminal of the low breakdown voltage switch 102 of the startup power supply unit 100.

  The NOT gate 302 has an input end and an output end. The input terminal of the NOT gate 302 is connected to the output terminal of the stop circuit 400. The output terminal of the NOT gate 302 is connected to one input terminal of the NOT OR gate 303.

  The NOR circuit 303 has two input terminals and an output terminal. One input terminal of the NOR gate 303 is connected to the output terminal of the NOT gate 302. The other input terminal of the negative OR gate 303 is connected to the output terminal of the UVLO 600. The output terminal of the NOR gate 303 is connected to the control terminal of the low breakdown voltage switch 103 of the startup power supply unit 100.

  The stop circuit 400 is connected to the voltage detection unit 200, the startup power supply control unit 300, the UVLO 600, the power factor correction circuit control unit 800, and the step-down chopper circuit control unit 900. Further, the stop circuit 400 is connected to the microcomputer 5, for example, via the CONT terminal of the control circuit 30.

  For example, the microcomputer 5 outputs a signal representing the standby mode or the steady mode to the stop circuit 400 of the control circuit 30 via the CONT terminal. In the control circuit 30, the stop circuit 400 outputs the signal S1 in response to the signal output from the microcomputer 5. In the control circuit 30, the signal S1 is controlled to be low level in the standby mode and high level in the steady mode.

  The stop circuit 400 outputs the signal S1 to the voltage detection unit 200, the startup power supply control unit 300, the power factor correction circuit control unit 800, and the step-down chopper circuit control unit 900.

  If an abnormality occurs in the switching power supply 1 or the load 70, the microcomputer 5 detects the abnormality and outputs a signal indicating the abnormal mode to the stop circuit 400 of the control circuit 30 via the CONT terminal. In this case, the stop circuit 400 sets the signal S1 to the low level as in the standby mode.

  In addition, the stop circuit 400 is connected to the first detection point 40 via the MULTI terminal of the control circuit 30, monitors the input voltage of the switching power supply 1, and based on the input voltage of the switching power supply 1, the voltage detection unit 200. The power supply controller 300 and the power factor correction circuit controllers 800 and 900 are configured to output a signal S1.

  The UVLO 600 is a block having a so-called under voltage lockout function. The UVLO 600 monitors the Vcc terminal voltage of the control circuit 30 and outputs a signal S0 to the voltage detection unit 200, the startup power supply control unit 300, and the stop circuit 400 corresponding to the Vcc terminal voltage.

  The UVLO 600 is in the UVLO operation for operating the low voltage lockout function (for example, when the Vcc terminal voltage is less than a predetermined voltage), the signal S0 is at a high level, and at the time of UVLO release for canceling the low voltage lockout function (for example, Vcc When the terminal voltage is equal to or higher than a predetermined voltage), the signal S0 is set to the low level.

  The stop circuit 400 sets the signal S1 to the low level corresponding to the high level signal S0 output from the UVLO 600, and sets the signal S1 to the high level corresponding to the low level signal S0 output from the UVLO 600.

  The power factor correction circuit control unit 800 monitors the voltage input to the power factor correction circuit unit 80 by detecting the first detection point voltage Vd1 via the MULTI terminal of the control circuit 30, and the first detection point voltage Vd1. Based on the above, the switching of the first switching element 81 is controlled.

  Further, the power factor correction circuit control unit 800 controls the output voltage of the power factor correction circuit unit 80 at a constant voltage by detecting the second detection point voltage Vd2 via the VFB terminal of the control circuit 30.

  With this configuration, there is no need to separately provide a circuit for detecting the input voltage of the power factor correction circuit unit 80 or a circuit for detecting the output voltage of the power factor correction circuit unit 80, and the configuration of the switching power supply 1 is simplified. can do.

  The step-down chopper circuit control unit 900 detects the output current of the step-down chopper circuit unit 90, and outputs the output current of the step-down chopper circuit unit 90 under constant current control.

  The control circuit 30 is preferably configured as a semiconductor integrated circuit formed on a predetermined semiconductor substrate in that the configuration of the control circuit 30 and the switching power supply 1 can be simplified.

  In this case, the semiconductor substrate is mounted on a predetermined module having a MULTI terminal as a first detection point voltage terminal that detects the first detection point voltage Vd1, and the MULTI terminal includes the voltage detection unit 200 and the power factor correction circuit control unit. It is assumed that 800 is connected.

  That is, the voltage detection unit 200 detects the first detection point voltage Vd1 and the power factor correction circuit control unit 800 monitors the voltage input to the power factor improvement circuit unit 80 via the MULTI terminal. To do.

  Here, the operation of the control circuit 30 in the first embodiment will be described with reference to FIG. In FIG. 8, the signal S1 output from the stop circuit 400 and the signal S0 output from the UVLO 600 both show waveforms under conditions that are low levels (standby mode, UVLO release conditions).

  In the first embodiment, the startup power supply unit 100 receives control power necessary for switching control via the switch 101, the low withstand voltage switch 102, and the like to start the operation of switching control, and the voltage detection unit 210 The first detection point voltage Vd1 whose potential changes corresponding to the AC phase to be detected is detected, and the startup power supply control unit 300 controls the operation of the startup power supply unit 100 based on the first detection point voltage Vd1.

  In the standby mode, the signal S1 output from the stop circuit 400 is at a low level, and the voltage detection unit 210 outputs, for example, a high level signal S2 when the first detection point voltage Vd1 is less than a predetermined first reference voltage Vth1. Output.

  When the voltage detection unit 210 outputs a high level signal S2, for example, the startup power supply control unit 300 outputs a low level signal S3 to the startup power supply unit 100, turns on the low withstand voltage switch 102, and flows the switch current I102 to control. The startup power supply unit 100 is controlled to receive power (T1 in FIG. 8).

  As a result, in the control circuit 30, the startup power supply unit 100 receives the control power necessary for the switching control, and starts the switching control operation of the switching power supply 1.

  In the first embodiment, for example, when the first detection point voltage Vd1 is equal to or higher than the predetermined first reference voltage Vth1 under the condition that the signal S1 output from the stop circuit 400 is at a low level (standby mode), The voltage detector 210 outputs, for example, a low level signal S2.

  When the voltage detection unit 210 outputs, for example, a low level signal S2, the activation power source control unit 300 outputs a high level signal S3 to the activation power source unit 100 so as not to turn off the low withstand voltage switch 102 and receive control power. The startup power supply unit 100 is controlled (T2 in FIG. 8).

  It should be noted that the time represented by T2 in FIG. 8 can be appropriately changed by appropriately setting the first reference voltage Vth1 according to the control power required by the control circuit 30.

  In FIG. 8, the signal S1 and the signal S0 are described as being at a low level. Therefore, under the conditions shown in FIG. 8, the start-up power supply control unit 300 outputs a low level signal S4 to the power supply start-up unit 100 based on the signal S1 and the signal S0 to turn off the low withstand voltage switch 103, thereby The startup power supply unit 100 is controlled not to receive control power via the switch 101, the resistor 104, the switch 103, and the diode 110.

  As described above, in the conventional control circuit, current always flows from the DC power supply Vdc to the control circuit via the dropper circuit during the operation of the control circuit, so that the electric power P represented by the above equation (1) is consumed. Is done.

  On the other hand, in the first embodiment, for example, in the standby mode, when the voltage changing corresponding to the phase of the alternating current input to the switching power supply 1 is equal to or higher than a predetermined voltage (represented by T2 in FIG. 8). Since the control power is controlled so as not to receive the control power, the standby power can be reduced while the control power is stably supplied to the control circuit 30.

  As described above, according to the control circuit 30 according to the first embodiment, the startup power supply unit 100 receives the control power necessary for the switching control via the switch 101 and the low breakdown voltage switch 102 and performs the operation of the switching control. The voltage detection unit 210 is started, and the voltage detection unit 210 is a first detection point that is a difference between the potential of the first detection point 40 where the potential changes corresponding to the input AC phase and the reference potential of the reference point 50 of the switching power supply. The startup power supply control unit 300 detects the voltage Vd1 and controls the operation of the startup power supply unit 100 based on the first detection point voltage Vd1. Therefore, the control power can be stably supplied to the control circuit 30 and the standby power can be reduced.

  In particular, according to the control circuit 30 according to the first embodiment, the startup power supply control unit 300 turns on the low breakdown voltage switch 102 when the first detection point voltage Vd1 is lower than the predetermined first reference voltage Vth1. The start-up power supply unit 100 is controlled to receive control power, and when the first detection point voltage Vd1 is equal to or higher than the first reference voltage Vth1, the start-up power supply unit 100 is turned off so as not to receive control power by turning off the low withstand voltage switch 102. Control. Therefore, the control power can be stably supplied to the control circuit 30 and the standby power can be reduced.

(Second Embodiment)
Next, a second embodiment will be described with reference to the drawings. Here, in the configuration of the control circuit 30, the configuration other than the voltage detection unit 200 is the same as that of the first embodiment, and therefore only the portions different from the configuration of the first embodiment will be described.

  FIG. 5 is a block circuit diagram showing a configuration example of a voltage detection unit 230 as an example of the voltage detection unit 200 in FIG.

  FIG. 9 is a waveform diagram (input AC voltage) of the first detection point voltage Vd1, the second detection point voltage Vd2, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the second embodiment of the present invention. Example under the condition of Vin = AC100V). FIG. 10 is a waveform diagram (input AC voltage) of the first detection point voltage Vd1, the second detection point voltage Vd2, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the second embodiment of the present invention. Example under the condition of Vin = AC200V).

  In the second embodiment, the voltage detection unit 200 includes, for example, a comparator 231, a negative AND gate 232, a first reference voltage power supply unit 233, a NOT gate 234, RS, as illustrated in the voltage detection unit 230 of FIG. The flip-flop 235, the AND gate 236, the comparator 237, and the second reference voltage power supply unit 238 are combined.

  The comparator 231 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the comparator 231 is connected to the first detection point 40 via the MULTI terminal of the control circuit 30.

  The inverting input terminal of the comparator 231 is connected to the reference voltage output terminal 233 b of the first reference voltage power supply unit 233. The output terminal of the comparator 231 is connected to the first input terminal of the NAND gate 232.

  The comparator 231 outputs a low level signal from the output terminal of the NAND gate 232 when the voltage at the MULTI terminal of the control circuit 30 is lower than the predetermined first reference voltage Vth1 generated by the first reference voltage power supply unit 233. Output to the first input terminal.

  In addition, the comparator 231 performs a NAND operation on a high-level signal from the output terminal when the voltage at the MULTI terminal of the control circuit 30 is equal to or higher than a predetermined first reference voltage Vth1 generated by the first reference voltage power supply unit 233. 232 to the first input terminal.

  The NAND gate 232 has three input terminals and an output terminal. The first input terminal of the NAND gate 232 is connected to the output terminal of the comparator 231. The second input terminal of the NAND gate 232 is connected to the output terminal of the NOT gate 234.

  A third input terminal of the NAND gate 232 is connected to the output terminal Q of the RS flip-flop 235. The output terminal of the NAND gate 232 is connected to the input terminal of the NOT gate 301 in the startup power supply control unit 300.

  The first reference voltage power supply unit 233 has an input terminal 233a and a reference voltage output terminal 233b. The input terminal 233 a of the first reference voltage power supply unit 233 is connected to the output terminal 120 b of the dropper circuit 120 in the startup power supply unit 100.

  The reference voltage output terminal 233 b of the first reference voltage power supply unit 233 is connected to the inverting input terminal of the comparator 231. The reference voltage output terminal 233b of the first reference voltage power supply unit 233 is configured to generate a predetermined first reference voltage Vth1.

  The NOT gate 234 has an input end and an output end. The input terminal of the NOT gate 234 is connected to the output terminal of the stop circuit 400. The output terminal of the NOT gate 234 is connected to the second input terminal of the NAND gate 232 and the other input terminal of the AND gate 236.

  The RS flip-flop 235 has a set input terminal S, a reset input terminal R, and an output terminal Q. The set input terminal S is connected to the output terminal of the AND gate 236. The reset input terminal R is connected to the output terminal of the UVLO 600. The output terminal Q is connected to the third input terminal of the NAND gate 232.

  When a high level signal is input to the set input terminal S, the RS flip-flop 235 outputs and holds a high level signal at the output terminal Q. Further, when a high level signal is input to the reset input terminal R, the RS flip-flop 235 outputs and holds a low level signal at the output terminal Q.

  The RS flip-flop 235 gives priority to resetting, for example, and when a high level signal is input to the set input terminal S and the reset input terminal R, the low level signal is output and held at the output terminal Q.

  The AND gate 236 has two input ends and an output end. One input terminal of the AND gate 236 is connected to the output terminal of the comparator 237. The other input terminal of the AND gate 236 is connected to the output terminal of the NOT gate 234. The output terminal of the AND gate 236 is connected to the set input terminal S of the RS flip-flop 235.

  The comparator 237 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the comparator 237 is connected to the second detection point 60 via the VFB terminal of the control circuit 30.

  The inverting input terminal of the comparator 237 is connected to the output terminal 238 b of the second reference voltage power supply unit 238. The output terminal of the comparator 237 is connected to one input terminal of the AND gate 236.

  The comparator 237 outputs a low level signal from the output terminal when the voltage at the VFB terminal of the control circuit 30 is less than a predetermined second reference voltage Vth2 generated by the second reference voltage power supply unit 238.

  The comparator 237 outputs a high level signal from the output terminal when the voltage at the VFB terminal of the control circuit 30 is equal to or higher than a predetermined second reference voltage Vth2 generated by the second reference voltage power supply unit 238.

  The second reference voltage power supply unit 238 has an input terminal 238a and a reference voltage output terminal 238b. The input terminal 238 a of the second reference voltage power supply unit 238 is connected to the output terminal 120 b of the dropper circuit 120 in the startup power supply unit 100.

  The reference voltage output terminal 238 b of the second reference voltage power supply unit 238 is connected to the inverting input terminal of the comparator 237. A predetermined second reference voltage Vth2 is generated at the reference voltage output terminal 238b of the second reference voltage power supply unit 238.

  For example, the voltage detection unit 230 is configured to detect the first detection point voltage Vd1 and the second detection point voltage Vd2 when the signal S1 output from the stop circuit 400 is at a low level (standby mode).

  The startup power supply control unit 300 in the second embodiment has the same configuration as that in the first embodiment, but the input terminal of the NOT gate 301 is connected to the output terminal of the NAND gate 232 of the voltage detection unit 230. It is connected.

  In the second embodiment, the startup power supply control unit 300 outputs the voltage detection unit 200 (the voltage detection unit 230 in the second embodiment) based on the first detection point voltage Vd1 and the second detection point voltage Vd2. The operation of the startup power supply unit 100 is controlled in response to the signal S2.

  The startup power supply control unit 300 controls the operation of the startup power supply unit 100 in response to the signal S1 output from the stop circuit 400 and the signal S0 output from the UVLO 600.

  Here, with reference to FIG. 9 and FIG. 10, the operation of the control circuit 30 in the second embodiment will be described. In FIGS. 9 and 10, the signal S1 output from the stop circuit 400 and the signal S0 output from the UVLO 600 show waveforms under conditions that are both low level (standby mode, UVLO release condition).

  For example, the voltage detection unit 230 is configured such that the second detection point voltage Vd2 is a predetermined first level when the signal S1 output from the stop circuit 400 is in a low level condition (standby mode) and the input AC voltage Vin = AC100V. When the voltage is less than 2 reference voltage Vth2, for example, a high level signal S2 is output (T3 in FIG. 9).

  For example, the voltage detection unit 230 is configured such that the second detection point voltage Vd2 is the second reference when the signal S1 output from the stop circuit 400 is in a low level condition (standby mode) and the input AC voltage Vin = AC200V. When the voltage is equal to or higher than the voltage Vth2 and the first detection point voltage Vd1 is lower than the first reference voltage Vth1, for example, a high level signal S2 is output (T4 in FIG. 10).

  In addition, the voltage detection unit 230 has, for example, a condition where the signal S1 output from the stop circuit 400 is at a low level (standby mode) and the second detection point voltage Vd2 is the second detection point voltage when the input AC voltage Vin = AC200V. When the reference voltage Vd2 is equal to or higher than the second reference voltage Vth2 and the first detection point voltage Vd1 is equal to or higher than the first reference voltage Vth1, for example, a low level signal S2 is output (T5 in FIG. 10).

  For example, the startup power supply control unit 300 is configured such that the second detection point voltage Vd2 is a predetermined value when the signal S1 output from the stop circuit 400 is in a low level condition (standby mode) and the input AC voltage Vin = AC100V. When the voltage is lower than the second reference voltage Vth2, in response to, for example, the high level signal S2 output from the voltage detection unit 230, the low level signal S3 is output to the startup power supply unit 100, and the low breakdown voltage switch 102 is turned on. Then, the startup power supply unit 100 is controlled to receive the control power (T3 in FIG. 9).

  For example, the startup power supply control unit 300 is configured such that the second detection point voltage Vd2 is the second when the signal S1 output from the stop circuit 400 is in a low level condition (standby mode) and the input AC voltage Vin = AC200V. When the reference voltage Vth2 is equal to or higher than the first detection voltage Vd1 and the first detection voltage Vd1 is lower than the first reference voltage Vth1, the low level signal S3 is output in response to the high level signal S2 output from the voltage detection unit 230, for example. The activation power supply unit 100 is output to the activation power supply unit 100, and the low voltage switch 102 is turned on to control the activation power supply unit 100 to receive the control power (T4 in FIG. 10).

  In addition, the startup power supply control unit 300 is configured such that, for example, when the signal S1 output from the stop circuit 400 is in a low level condition (standby mode) and the input AC voltage Vin = AC200V, the second detection point voltage Vd2 is When the first reference voltage Vd1 is equal to or higher than the second reference voltage Vth2 and the first detection voltage Vd1 is equal to or higher than the first reference voltage Vth1, a high level signal corresponding to, for example, the low level signal S2 output from the voltage detector 230. S3 is output to the startup power supply unit 100, and the startup power supply unit 100 is controlled not to receive control power by turning off the low withstand voltage switch 102 (T5 in FIG. 10).

  Note that the time represented by T5 in FIG. 10 can be changed as appropriate according to the control power required by the control circuit 30 if the first reference voltage Vth1 is appropriately set.

  As described above, in FIGS. 9 and 10, the signal S1 and the signal S0 are both assumed to be at the low level. Therefore, under the conditions shown in FIGS. 9 and 10, the startup power supply control unit 300 outputs the low level signal S4 to the power supply startup unit 100 based on the signal S1 and the signal S0 to turn off the low breakdown voltage switch 103. The startup power supply unit 100 is controlled not to receive control power through the high voltage switch 101, the resistor 104, the switch 103, and the diode 110.

  As described above, according to the control circuit 30 according to the second embodiment, for example, in the standby mode, the startup power supply control unit 300 detects the voltage based on the first detection point voltage Vd1 and the second detection point voltage Vd2. The operation of startup power supply unit 100 is controlled in response to signal S2 output from unit 200 (voltage detection unit 230 in the second embodiment). Accordingly, control power can be stably supplied to the control circuit, and standby power can be reduced.

  Further, according to the control circuit 30 according to the second embodiment, the start-up power supply control unit 300 has a low breakdown voltage when the second detection point voltage Vd2 is less than the predetermined second reference voltage Vth2, for example, in the standby mode. The startup power supply unit 100 is controlled to turn on the switch 102 to receive control power, the second detection point voltage Vd2 is equal to or higher than the second reference voltage Vth2, and the first detection point voltage Vd1 is lower than the first reference voltage Vth1. In this case, the start-up power supply unit 100 is controlled so as to receive the control power by turning on the low withstand voltage switch 102, the second detection point voltage Vd2 is equal to or higher than the second reference voltage Vth2, and the first detection point voltage Vd1 is the first. When the reference voltage is equal to or higher than Vth1, the low power switch 102 is turned off to control the startup power supply unit 100 so as not to receive control power. Therefore, when the input AC voltage is less than the predetermined voltage, the control power is stably supplied to the control circuit 30. When the input AC voltage is equal to or higher than the predetermined voltage, standby power is reduced. Can be achieved.

(Third embodiment)
Next, a third embodiment will be described with reference to the drawings. Here, the configuration of the control circuit 30 other than the voltage detection unit 200 is the same as that of the first embodiment and the second embodiment, and therefore the configuration of the first embodiment and the second embodiment. Different parts will be described.

  FIG. 6 is a block circuit diagram illustrating a configuration example of a voltage detection unit 250 as an example of the voltage detection unit 200 in FIG. FIG. 11 is a waveform diagram (input AC voltage) of the first detection point voltage Vd1, the second detection point voltage Vd2, the switch current I102, the signal S1, the signal S2, the signal S3, and the signal S4 according to the third embodiment of the present invention. Example under the condition of Vin = AC100V and input AC voltage Vin = AC200V).

  In the third embodiment, the voltage detection unit 200 includes, for example, a comparator 251, a negative AND gate 252, a first reference voltage power supply unit 253, a NOT gate 254, RS, as illustrated in the voltage detection unit 250 of FIG. The flip-flop 255, the AND gate 256, the comparator 257, and the second reference voltage power supply unit 258 are combined.

  The comparator 251 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the comparator 251 is connected to the first detection point 40 via the MULTI terminal of the control circuit 30.

  The inverting input terminal of the comparator 251 is connected to the reference voltage output terminal 253 b of the first reference voltage power supply unit 253. The output terminal of the comparator 251 is connected to one input terminal of the NAND gate 252.

  The comparator 251 outputs a low level signal from the output terminal when the voltage at the MULTI terminal of the control circuit 30 is lower than the predetermined first reference voltage Vth1 generated by the first reference voltage power supply unit 253.

  The comparator 251 outputs a high level signal from the output terminal when the voltage at the MULTI terminal of the control circuit 30 is equal to or higher than a predetermined first reference voltage Vth1 generated by the first reference voltage power supply unit 253.

  The NAND gate 252 has two input ends and an output end. One input terminal of the NAND gate 252 is connected to the output terminal of the comparator 251. The other input terminal of the NAND gate 252 is connected to the output terminal of the NOT gate 254. The output terminal of the NAND gate 252 is connected to the input terminal of the NOT gate 301 in the startup power supply control unit 300.

  The first reference voltage power supply unit 253 has an input terminal 253a, a reference voltage output terminal 253b, and a reference voltage setting terminal 253c. The input terminal 253 a of the first reference voltage power supply unit 253 is connected to the output terminal 120 b of the dropper circuit 120 in the startup power supply unit 100.

  The reference voltage output terminal 253 b of the first reference voltage power supply unit 253 is connected to the inverting input terminal of the comparator 251. The reference voltage output terminal 253b of the first reference voltage power supply unit 253 is configured to generate a predetermined first reference voltage Vth1.

  The reference voltage setting terminal 253 c of the first reference voltage power supply unit 253 is connected to the output terminal Q of the RS flip-flop 255. The first reference voltage power supply unit 253 generates the first reference voltage Vth1 generated at the reference voltage output terminal 253b of the first reference voltage power supply unit 253 in response to the signal output from the output terminal Q of the RS flip-flop 255. For example, the first reference voltage Vth1 is set to be directly proportional to the second detection point voltage Vd2.

  As a specific example, the first reference voltage Vth1 is set to 1.25V when the input AC is 100V AC, and the first reference voltage Vth1 is 2.50V when the input AC is AC 200V.

  As described above, when the first reference voltage Vth1 is set to two values corresponding to when the input AC is 100V AC and 200V AC, the control circuit 30 can be simplified.

  In such a setting, the comparator 257 compares the voltage of the VFB terminal of the control circuit 30 with the predetermined second reference voltage Vth2 generated by the second reference voltage power supply unit 258, and the RS flip-flop 255 This is done by switching the input signal to the set input terminal S.

  Note that, as described above, the VFB terminal of the control circuit 30 divides the smoothed voltage obtained by full-wave rectifying the input alternating current when the signal S1 output from the stop circuit 400 is in the low level (standby mode). The applied voltage (second detection point voltage Vd2) is applied. For this reason, the first reference voltage Vth1 is set according to the AC voltage input in the standby mode.

  The NOT gate 254 has an input end and an output end. The input terminal of the NOT gate 254 is connected to the output terminal of the stop circuit 400. The output terminal of the NOT gate 254 is connected to the other input terminal of the logical product gate 256 and the other input terminal of the negative logical product gate 252.

  The RS flip-flop 255 has a set input terminal S, a reset input terminal R, and an output terminal Q. The set input terminal S is connected to the output terminal of the AND gate 256. The reset input terminal R is connected to the output terminal of the UVLO 600. The output terminal Q is connected to the reference voltage setting terminal 253c of the first reference voltage power supply unit 253.

  When a high level signal is input to the set input terminal S, the RS flip-flop 255 outputs and holds a high level signal at the output terminal Q. In addition, when a high level signal is input to the reset input terminal R, the RS flip-flop 255 outputs and holds a low level signal at the output terminal Q.

  The RS flip-flop 255 gives priority to resetting, for example, and when a high level signal is input to the set input terminal S and the reset input terminal R, the low level signal is output and held at the output terminal Q.

  The AND gate 256 has two input ends and an output end. One input terminal of the AND gate 256 is connected to the output terminal of the comparator 257. The other input terminal of the AND gate 256 is connected to the output terminal of the NOT gate 254. The output terminal of 256 is connected to the set input terminal S of the RS flip-flop 255.

  The comparator 257 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the comparator 257 is connected to the second detection point 60 via the VFB terminal of the control circuit 30.

  The inverting input terminal of the comparator 257 is connected to the reference voltage output terminal 258 b of the second reference voltage power supply unit 258. The output terminal of the comparator 257 is connected to one input terminal of the AND gate 256.

  The comparator 257 outputs a low level signal from the output terminal when the voltage at the VFB terminal of the control circuit 30 is less than a predetermined second reference voltage Vth2 generated by the second reference voltage power supply unit 258. The comparator 257 outputs a high level signal from the output terminal when the voltage at the VFB terminal of the control circuit 30 is equal to or higher than a predetermined second reference voltage Vth2 generated by the second reference voltage power supply unit 258.

  The second reference voltage power supply unit 258 has an input terminal 258a and a reference voltage output terminal 258b. The input terminal 258 a of the second reference voltage power supply unit 258 is connected to the output terminal 120 b of the dropper circuit 120 in the startup power supply unit 100.

  The reference voltage output terminal 258 b of the second reference voltage power supply unit 258 is connected to the inverting input terminal of the comparator 257. The reference voltage output terminal 258b of the second reference voltage power supply unit 258 is configured to generate a predetermined second reference voltage Vth2.

  For example, the voltage detection unit 250 is configured to detect the first detection point voltage Vd1 and the second detection point voltage Vd2 when the signal S1 output from the stop circuit 400 is at a low level (standby mode).

  The voltage detection unit 250 sets the first reference voltage Vth1 corresponding to the second detection point voltage Vd2, and sets the first reference voltage Vth1 so as to be directly proportional to the second detection point voltage Vd2, for example. As described above, since the standby mode is controlled so that the power factor correction circuit unit 80 does not perform the switching operation, the second detection point voltage Vd2 is obtained by dividing the input alternating current by full-wave rectification and dividing the voltage. It becomes the electric potential.

  For example, the second detection point voltage Vd2 under the condition of the input AC voltage Vin = AC200V is a value that is directly proportional to the second detection point voltage Vd2 under the condition of the input AC voltage Vin = AC100V.

  Therefore, in the voltage detection unit 250, the first reference voltage Vth1 under the condition of the input AC voltage Vin = AC200V is set to a value that is directly proportional to the first reference voltage Vth1 under the condition of the input AC voltage Vin = AC100V.

  Note that the startup power supply control unit 300 in the third embodiment has the same configuration as that of the first and second embodiments, but one input terminal of the NOT gate 301 is negated by the voltage detection unit 250. The output terminal of the AND gate 252 is connected.

  In the third embodiment, the startup power supply controller 300 outputs the voltage detector 200 (the voltage detector 250 in the third embodiment) based on the first detection point voltage Vd1 and the second detection point voltage Vd2. The operation of the startup power supply unit 100 is controlled in response to the signal S2.

  The startup power supply control unit 300 controls the operation of the startup power supply unit 100 in response to the signal S1 output from the stop circuit 400 and the signal S0 output from the UVLO 600.

  Here, the operation of the control circuit 30 in the third embodiment will be described with reference to FIG. In FIG. 11, the signal S1 output from the stop circuit 400 and the signal S0 output from the UVLO 600 both show waveforms under conditions that are low levels (standby mode, UVLO release conditions).

  In the voltage detector 250 in which the first reference voltage Vth1 is set as described above, as shown in FIG. 11, when the first detection point voltage Vd1 is lower than the set first reference voltage Vth1, for example, High A level signal S2 is output (T6 in FIG. 11).

  Further, when the first detection point voltage Vd1 is equal to or higher than the first reference voltage Vth1 set as described above, the voltage detection unit 250 outputs, for example, a low level signal S2 (T7 in FIG. 11).

  The time when the signal S2 output from the voltage detection unit 250 is at a high level is controlled to be a predetermined time (T6 in FIG. 11) under the conditions of the input AC voltage Vin = AC100V and the input AC voltage Vin = AC200V.

  For example, when the first detection point voltage Vd1 is less than the first reference voltage Vth1 set as described above under the condition that the signal S1 output from the stop circuit 400 is at a low level (standby mode), In response to, for example, a high level signal S2 output from the detection unit 250, a low level signal S3 is output to the activation power source unit 100, and the low voltage switch 102 is turned on to receive control power. Is controlled (T6 in FIG. 11).

  For example, when the first detection point voltage Vd1 is equal to or higher than the first reference voltage Vth1 set above in the condition (standby mode) where the signal S1 output from the stop circuit 400 is low level, In response to, for example, the Low level signal S2 output from the detection unit 210, the High level signal S3 is output to the start power supply unit 100, and the low voltage switch 102 is turned off so that the control power is not received. Is controlled (T7 in FIG. 11).

  Note that the time represented by T7 in FIG. 11 can be appropriately changed by appropriately setting the first reference voltage Vth1 according to the control power required by the control circuit 30.

  In FIG. 11, the signal S1 and the signal S0 are described as being at a low level. Therefore, under the conditions shown in FIG. 11, the startup power supply control unit 300 outputs a low level signal S4 to the power supply startup unit 100 based on the signals S1 and S0 to turn off the low breakdown voltage switch 103, thereby The startup power supply unit 100 is controlled not to receive control power via the switch 101, the resistor 104, the switch 103, and the diode 110.

  The voltage detection unit 250 sets the first reference voltage Vth1 corresponding to (for example, directly proportional to) the second detection point voltage Vd2. As described above, in the standby mode, the switching operation by the power factor correction circuit unit 80 is not performed, so the voltage of the smoothing unit 20 is not boosted, and the input AC is full-wave rectified and the smoothed voltage is applied to the smoothing unit 20. Applied. Therefore, the second detection point voltage Vd2 includes the input AC voltage information.

  Therefore, when the first reference voltage Vth1 is set corresponding to (for example, directly proportional to) the second detection point voltage Vd2, the timing for detecting the first detection point voltage Vd1 can be made to correspond to the input AC voltage.

  Therefore, as shown in FIG. 11, for example, it is possible to match the timing of detecting the first detection point voltage Vd1 under the conditions of the input AC voltages AC100V and AC200V, and the signal S2 output by the voltage detection unit 250 By controlling so that the high level time is the predetermined time T6, the ON time of the low withstand voltage switch 102 is controlled to be the predetermined time T6. (T6 in FIG. 11).

  As described above, according to the control circuit 30 according to the third embodiment, for example, in the standby mode, the startup power supply control unit 300 detects the voltage based on the first detection point voltage Vd1 and the second detection point voltage Vd2. The operation of startup power supply unit 100 is controlled in response to signal S2 output from unit 200 (voltage detection unit 250 in the third embodiment). Therefore, the control power can be stably supplied to the control circuit 30 and the standby power can be reduced.

  In particular, the voltage detection unit 250 sets the first reference voltage Vth1 corresponding to the second detection point voltage Vd2, for example, sets the first reference voltage Vth1 to be directly proportional to the second detection point voltage Vd2.

  In addition, for example, when the first detection point voltage Vd1 is equal to or higher than the first reference voltage Vth1 set in the condition (standby mode) in which the signal S1 output from the stop circuit 400 is at a low level, the start-up power supply control unit 300 For example, based on the low-level signal S2, the high-level signal S3 is output to the startup power supply unit 100, and the low-voltage switch 102 is turned off to control the startup power supply unit 100 so as not to receive control power.

  Further, for example, when the first detection point voltage Vd1 is less than the first reference voltage Vth1 set as described above in the condition (standby mode) where the signal S1 output from the stop circuit 400 is Low level, For example, based on the high-level signal S2, the low-level signal S3 is output to the start-up power supply unit 100, the low withstand voltage switch 102 is turned on, the switch current I102 is supplied, and the start-up power supply unit 100 is controlled to receive control power. .

  Therefore, according to the control circuit 30 according to the third embodiment, as shown in FIG. 11, the on-time of the low withstand voltage switch 102 sets the first reference voltage Vd1 corresponding to the input AC voltage. Thus, the predetermined time T6 is controlled. Thereby, even when the AC voltage input to the switching power supply 1 fluctuates, the control power can be stably supplied to the control circuit 30, and the standby power can be reduced.

  In the first to third embodiments described above, the first detection point 40 is configured to be provided on the input side of the rectifying unit 10, so that the information on the AC voltage input to the switching power supply 1 is accurately detected. It is possible to reliably supply control power to the control circuit, and to reduce standby power.

  In the first to third embodiments, the switching power supply 1 includes the first switching element 81 and includes the power factor improvement circuit unit 80 that improves the power factor of the switching power supply 1 by the switching operation of the first switching element 81. The power factor improvement circuit control unit 800 monitors the voltage input to the power factor improvement circuit unit 80 by detecting the first detection point voltage Vd1, and based on the first detection point voltage Vd1, the first switching element 81 switching is controlled.

  Therefore, it is not necessary to separately provide a circuit for detecting the input voltage of the power factor correction circuit unit 80, and the configuration of the switching power supply 1 can be simplified.

  In the first to third embodiments, the power factor improvement circuit control unit 800 controls the output voltage of the power factor improvement circuit unit by constant voltage by detecting the second detection point voltage Vd2. Therefore, it is not necessary to separately provide a circuit for detecting the output voltage of the power factor correction circuit unit 80, and the configuration of the switching power supply 1 can be simplified.

  In the first to third embodiments, the switching power supply 1 includes the step-down chopper circuit unit 90 and steps down the output voltage of the power factor correction circuit unit 80 by the switching operation of the second switching element 91 and outputs it. Therefore, the switching power supply 1 can be configured as a power supply for various applications.

  In the first to third embodiments, the step-down chopper circuit control unit 900 detects the output current of the step-down chopper circuit unit 90 and outputs the output current of the step-down chopper circuit unit 90 with constant current control. Therefore, a switching power supply suitable for a load such as LED lighting that requires constant current control can be configured.

  In the first to third embodiments, if the control circuit 30 is configured as a semiconductor integrated circuit formed on a predetermined semiconductor substrate, the configuration of the control circuit 30 and the switching power supply 1 can be simplified.

  In the first to third embodiments, the semiconductor substrate is mounted on a predetermined module having a first detection point voltage terminal (MULTI terminal) that detects the first detection point voltage Vd1, and the first detection point voltage terminal The (MULTI terminal) is connected to the voltage detection unit 200 and the power factor correction circuit control unit 800, and the voltage detection unit 200 detects the first detection point voltage Vd1 via the first detection point voltage terminal (MULTI terminal). The power factor correction circuit control unit 800 can be configured to monitor the voltage input to the power factor correction circuit unit 80.

  Therefore, when the control circuit 30 is configured to be mounted on a predetermined module as a semiconductor integrated circuit formed on a predetermined semiconductor substrate, the voltage detection unit 200 detects a first detection point voltage Vd1, a power factor, It is not necessary to separately provide a terminal for monitoring the voltage input to the power factor correction circuit unit 80 by the improvement circuit control unit 800, and the number of terminals of the module can be reduced.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation and application are possible within the range which does not deviate from the summary of this invention. For example, the logic relationship between the high level and the low level of the signals S0 to S4 and the configuration of the logic circuit components in the control circuit 30 are not limited to the above embodiment, and are within the scope of the invention. If necessary, it can be changed as appropriate.

1: Switching power supply 2: AC power supply 5: Microcomputer 10: Rectification unit 20: Smoothing unit 30: Control circuit 40: First detection point 43, 44: Resistance 50: Reference point 60: Second detection point 63: Resistance 64: Resistance 70: Load 80: Power factor correction circuit unit 90: Step-down chopper circuit unit 95: Auxiliary winding power source 100: Start-up power source unit 101: High breakdown voltage switch 102, 103: Low breakdown voltage switch 104, 105, 106: Resistance 107, 108: Zener diode 109, 110: Diode 120: Dropper circuit 200, 210, 230, 250: Voltage detection unit 211, 231, 251, 257: Comparator 212, 303: NOR gate 213, 233, 253: First reference voltage Power supply units 232, 252: NAND gates 234, 254, 301, 302: NOT gate 235 255: RS flip-flop 236 and 256: AND gate 238: second reference voltage power source 300: Start power control unit 400: stop circuit 600: UVLO
800: Power factor correction circuit control unit 900: Step-down chopper circuit control unit

Claims (4)

A rectifying unit that rectifies input alternating current and outputs direct current;
A smoothing unit for smoothing the direct current rectified by the rectifying unit;
A switching power supply unit that has a switching element, is connected between the rectifying unit and the smoothing unit, and / or connected to the output side of the smoothing unit, and switches the switching element;
In a switching power supply comprising: a control circuit used for switching control of the switching element,
An activation power supply unit that has a switch, receives the control power necessary for the switching control via the switch from the direct current output by the rectification unit, and starts the operation of the switching control;
A voltage detection unit that detects a first detection point voltage that is a difference between a potential at a first detection point at which a potential changes corresponding to the phase of the input AC and a reference potential at a reference point of the switching power supply;
A startup power supply controller that controls the operation of the startup power supply unit based on the first detection point voltage;
With
The steady mode in which the switching power supply unit is controlled to perform a switching operation, the switching power supply unit is controlled not to perform a switching operation , and the start-up power supply unit receives control power necessary for the switching control, and And a standby mode for starting the switching control operation of the switching power supply unit ,
In the standby mode, the startup power supply control unit controls the startup power supply unit to turn on the switch and receive the control power when the first detection point voltage is lower than a predetermined first reference voltage. A control circuit, wherein when the first detection point voltage is equal to or higher than the first reference voltage, the start-up power supply unit is controlled not to receive the control power by turning off the switch. The switching power supply unit is connected between the rectifying unit and the smoothing unit, includes a first switching element, and improves a power factor of the switching power supply by a switching operation of the first switching element. Department,
Power factor correction circuit control for monitoring the voltage input to the power factor correction circuit unit by detecting the first detection point voltage and controlling the switching of the first switching element based on the first detection point voltage. The control circuit according to claim 1, further comprising a unit. The switching power supply unit is connected to the output side of the smoothing unit, includes a second switching element, and a step-down chopper that steps down and outputs the output voltage of the power factor correction circuit unit by the switching operation of the second switching element. Circuit part,
The control circuit according to claim 2, further comprising a step-down chopper circuit control unit that controls switching of the second switching element. A rectifying unit that rectifies input alternating current and outputs direct current;
A smoothing unit for smoothing the direct current rectified by the rectifying unit;
A switching power supply unit that has a switching element, is connected between the rectifying unit and the smoothing unit, and / or connected to the output side of the smoothing unit, and switches the switching element;
A control circuit used for switching control of the switching element;
With
The control circuit includes:
An activation power supply unit that has a switch, receives the control power necessary for the switching control via the switch from the direct current output by the rectification unit, and starts the operation of the switching control;
A voltage detection unit for detecting a first detection point voltage is the difference between the reference potential of the reference point of potential and the switching power supply unit of the first detection point potential corresponding to the AC of the phase of said input changes ,
A startup power supply controller that controls the operation of the startup power supply unit based on the first detection point voltage;
With
The steady mode in which the switching power supply unit is controlled to perform a switching operation, the switching power supply unit is controlled not to perform a switching operation , and the start-up power supply unit receives control power necessary for the switching control, and and a standby mode is set to the operation of the switching control of the switching power supply unit in the state to initiate start,
In the standby mode, the startup power supply control unit controls the startup power supply unit to turn on the switch and receive the control power when the first detection point voltage is lower than a predetermined first reference voltage. When the first detection point voltage is equal to or higher than the first reference voltage, the switching power supply is controlled so as not to receive the control power by turning off the switch.

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