JP2006014509A - Switching power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power supply which can reduce power consumption, even at a normal operation state, not only at a stand-by state, and which can also reduce the switching noise at normal operation state. <P>SOLUTION: The switching power supply is provided with a microcomputer 100 including a function for outputting control signals P-ON_H1, P-ON_H2; a main power generating circuit 101 for outputting the voltage obtained by switching an input DC voltage VIN by an oscillating operation as a power to the load circuit of electronic equipment and to the microcomputer 100; a sub power generating circuit 102 for supplying the voltage obtained by switching the input DC voltage VIN by the oscillating operation as power to the microcomputer 100; and an oscillating switching circuit 105 for stopping the oscillating operation of the main power generating circuit 101 at the stand-by state and for stopping the oscillating operation of the sub power generating circuit 102 at the normal operation state based on the control signals P-ON_H1, P-ON_H2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a switching power supply device that supplies power to an electronic device, and more particularly to a switching power supply device that can reduce power consumption and switching noise.

In recent years, there are an increasing number of electronic devices such as TVCR (Television + Video Cassette Recorder) that are multifunctional. A power supply device that supplies power to such a multi-functional electronic device has a remarkable increase in output capacity and number of output systems. Such a power supply device outputs a stabilized voltage and has a power efficiency. A switching power supply device that is advantageous for low power consumption and miniaturization is used.

Also, an electronic device such as a TVCR needs to supply power during standby other than during normal operation. To reduce power consumption during standby, a switching power supply device that supplies power to such an electronic device is used. Operates a main power generation circuit for operating each operation unit in an electronic device and a microcomputer (hereinafter referred to as a microcomputer) that is a control unit including a function for controlling operation / stop of each operation unit. In many cases, a sub power supply generation circuit is provided.

The main power generation circuit generates an output voltage necessary for the operation of each operation unit and supplies the output voltage to each operation unit. The sub power generation circuit has a relatively low voltage (for example, about 5 V). An output voltage is generated and supplied as an operating voltage of the microcomputer.

The main power generation circuit and the sub power generation circuit both have a transformer to which an input DC voltage obtained by rectifying and smoothing an AC voltage from a commercial power supply is provided, and the input through the primary winding of the transformer. A switching element to which a DC voltage is applied is included. Each switching element is on / off controlled to rectify and smooth the voltage generated in the secondary winding of each transformer to obtain each output voltage.

When there is an instruction to turn on the electronic device, the main power generation circuit is operated by an on signal from the microcomputer. On the other hand, when there is an instruction to turn off the electronic device, the off signal from the microcomputer. Thus, the main power generation circuit is stopped and only the sub power generation circuit is operated to reduce the power consumption of the switching power supply device during standby.

Further, the power supply circuit supplies a first DC power from the first DC power supply in the power-on mode, and supplies a second DC power from the second DC power supply in the standby mode. 2. There is a power supply circuit that turns off a first DC power supply via a light emitting element connected to a DC power supply (see, for example, Patent Document 1).

The secondary side is provided with a main output having a relatively high voltage and a sub output having a relatively low voltage, and the voltage of the main output is fed back to the switching control means on the primary side via the optical coupling means. While performing the constant voltage control operation, the power load of the main output system is controlled by the load control unit of the sub output system, and during the standby operation, the load control unit stops the operation of the power load, There is also a switching power supply device in which a minimum output voltage can be obtained by causing the optical coupling means to blink in a pseudo intermittent oscillation output voltage (for example, see Patent Document 2).

In standby mode, AC supplied to the primary side of the main power supply circuit that supplies operating power to the load circuit
There is also a switching power supply circuit that turns off the power supply under the control of a microcomputer (see, for example, Patent Document 3).
JP-A-8-286770 JP 2003-199340 A Japanese Patent Laid-Open No. 2004-23894

However, in the conventional switching power supply device having the main power generation circuit and the sub power generation circuit as described above, the switching elements of both the main power generation circuit and the sub power generation circuit perform a switching operation during normal operation. As the level of switching noise increases, both switching cycles are not synchronized, which increases the frequency band of switching noise, which increases the possibility of adverse effects on other devices. . In addition, the power consumption increases because the switching elements of both the main power generation circuit and the sub power generation circuit perform the switching operation.

Further, the prior art described in Patent Document 1 uses a light emitting element and a light receiving element for on / off control of the first DC power supply, so that the primary side and the secondary side of the transformer are insulated while waiting. 1 The DC power supply is turned off. However, since the second DC power supply is always turned on, the same problems as those of the conventional switching power supply device having the main power generation circuit and the sub power generation circuit described above are included. Yes.

The prior art described in Patent Document 2 can reduce the power consumption by maintaining the output voltage of the main output at the lowest voltage by setting the intermittent oscillation state during standby, but supplies the main output. Therefore, the oscillation operation for this does not stop completely. Such a switching power supply is normally designed so that the output efficiency is maximized when the load that supplies the main output is the rated load, and measures are taken for the output efficiency related to the minimum load and the standby load. Since this is not done, there is a problem that wasteful power consumption increases even in an intermittent oscillation state during standby.

The prior art described in Patent Document 3 is an AC that is supplied to the primary side of the main power supply circuit during standby.
The power supply is turned off under the control of the microcomputer to reduce power consumption during standby, but the standby power supply circuit for operating the standby circuit such as the microcomputer is always turned on. The same problems as those of the conventional switching power supply device having the main power generation circuit and the sub power generation circuit are included.

In view of the above problems, the present invention can reduce power consumption not only during standby but also during normal operation, and reduces switching noise during normal operation and does not adversely affect other devices. An object of the present invention is to provide a switching power supply device that can be configured as described above.

In order to achieve the above object, a first aspect of the present invention is a switching power supply device that supplies power to an electronic device that can be switched between a normal operation state and a standby state, and outputs first and second control signals. The second control signal is changed from the third level to the fourth level when there is an instruction to switch from the standby state to the normal operation state, and after the first delay time from that time, the first control signal is changed. Is changed from the first level to the second level, and when there is an instruction to switch from the normal operation state to the standby state, the first control signal is changed from the second level to the first level. Including a microcomputer having a function of changing the second control signal from the fourth level to the third level after the second delay time from the first to the first winding of the first transformer and the first switching element. Input DC voltage is applied Main power generation circuit that outputs a voltage induced in the secondary winding of the first transformer by the oscillation operation of the first switching element as a power supply to the load circuit of the electronic device. A control power supply circuit that supplies a new voltage generated from the output voltage of the main power supply generation circuit as a power supply to the microcomputer, a primary winding of a second transformer, and a second switching element. A sub-circuit that has a second series circuit to which the input DC voltage is applied, and that supplies a voltage induced in the secondary winding of the second transformer by the oscillation operation of the second switching element as a power source to the microcomputer; When the power generation circuit and the second control signal are at the third level, the first switching element is turned off via the first optical coupling means, and the first control signal is When the bell to provide a switching power supply apparatus characterized by comprising an oscillation switching circuit for turning off the second switching element through the second optical coupling means.

According to this configuration, when the electronic device is in the standby state, the second from the microcomputer.
The control signal becomes the third level, and the oscillation switching circuit turns off the first switching element via the first optical coupling means. As a result, the main power generation circuit stops the oscillation operation, so that the power consumption of the switching power supply device in the standby state can be reduced. At this time, the first control signal from the microcomputer is at the first level, the sub power generation circuit performs an oscillating operation, and a voltage as a power source is supplied from the sub power generation circuit to the microcomputer. Can work.

When the electronic device is in a normal operation state, the second control signal from the microcomputer is at the fourth level, and the main power generation circuit performs an oscillation operation to supply a voltage as a power source to the load circuit of the electronic device. To do. In addition, since the control power supply circuit generates a new voltage from the output voltage of the main power supply generation circuit and supplies a voltage as a power supply to the microcomputer,
The microcomputer can operate. At this time, the first control signal from the microcomputer becomes the second level, and the oscillation switching circuit turns off the second switching element via the second optical coupling means. As a result, the sub power supply generation circuit stops the oscillation operation, so that the power consumption of the switching power supply device in the normal operation state can be reduced, and the switching by the oscillation of the main power supply generation circuit and the sub power supply generation circuit can be achieved. It is possible to prevent an increase in noise level and an expansion of the frequency band of switching noise.

Further, when the oscillation operation of the sub power generation circuit stops, the oscillation operation of the sub power generation circuit stops after the first delay time after the main power generation circuit oscillates. It can be prevented that neither the main power generation circuit nor the sub power generation circuit is supplied and the microcomputer stops.

Further, when the oscillation operation of the main power generation circuit stops, the oscillation operation of the main power generation circuit stops after the second delay time after the sub power generation circuit oscillates. It can be prevented that neither the main power generation circuit nor the sub power generation circuit is supplied and the microcomputer stops.

The invention according to claim 2 is a switching power supply device that supplies power to an electronic device that can be switched between a normal operation state and a standby state, and a control signal that is changed based on a switching instruction between the normal operation state and the standby state. A power source control circuit for outputting, a main power source generating circuit for outputting a voltage obtained by switching an input DC voltage by an oscillation operation as a power source for the load circuit of the electronic device and the power source control circuit, and the input DC by an oscillation operation A sub power generation circuit that supplies a voltage obtained by switching the voltage as power to the power control circuit, and an oscillation that stops the oscillation operations of the main power generation circuit and the sub power generation circuit based on the control signal, respectively. A switching circuit, and the power control block is configured so that the oscillation switching block is in the main oscillation circuit when in a standby state. The oscillation operation is stopped, so that when the normal operating state the oscillating switching block stops the oscillating operation of said sub-oscillation circuit, to provide a switching power supply apparatus characterized by varying the control signal.

According to this configuration, when the electronic device is in the standby state, the oscillation switching circuit stops the oscillation operation of the main power generation circuit based on the control signal from the power supply control circuit, so the power consumption of the switching power supply device in the standby state is reduced. Can be reduced. At this time, since the sub power generation circuit performs an oscillation operation to supply a voltage as a power source to the power control circuit, the power control circuit can operate.

Further, when the electronic device is in a normal operation state, the main power generation circuit performs an oscillating operation to supply a voltage as a power source to the load circuit and the power supply control circuit of the electronic device. Thereby, the power supply control circuit can operate. At this time, since the oscillation switching circuit stops the oscillation operation of the sub power generation circuit based on the control signal from the power control circuit, it is possible to reduce the power consumption of the switching power supply device in the normal operation state and It is possible to prevent an increase in the level of switching noise and an increase in the frequency band of the switching noise due to the oscillation of both the power generation circuit and the sub power generation circuit.

According to a third aspect of the present invention, there is provided the control power supply circuit according to the second aspect of the present invention, further comprising a control power supply circuit that supplies a new voltage generated from the output voltage of the main power generation circuit as a power source to the power control circuit. is there. According to this configuration, the power supply voltage necessary for the operation can be supplied to the power supply control circuit regardless of the value of the voltage output from the main power supply generation circuit.

According to a fourth aspect of the present invention, in the second or third aspect of the present invention, the main power generation circuit includes a primary winding of a first transformer and a first switching element, and is supplied with the input DC voltage. A first series circuit that outputs a voltage induced in the secondary winding of the first transformer by the oscillation operation of the first switching element;
A second series circuit including a secondary winding and a second switching element, to which the input DC voltage is applied, and is induced in the secondary winding of the second transformer by the oscillation operation of the second switching element; A voltage is output.

According to this configuration, the input DC voltage is switched by oscillating the first switching element, whereby the secondary winding of the first transformer is supplied as a power source to the load circuit and the power supply control circuit of the electronic device. Voltage can be induced. Also, the input DC voltage can be switched by oscillating the second switching element, thereby inducing a voltage to be supplied as a power source to the power supply control circuit in the secondary winding of the second transformer.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, the power supply control circuit outputs the first and second control signals, and the second control signal is output when an instruction to switch from the standby state to the normal operation state is given. The control signal is changed from the third level to the fourth level, and after that, after the first delay time, the first control signal is changed from the first level to the second level, and the normal operation state is changed to the standby state. The first control signal is changed from the second level to the first level when an instruction to switch to
After that, after the second delay time, the second control signal is changed from the fourth level to the third level. When the second control signal is at the third level, the oscillation switching circuit The switching element is turned off, and when the first control signal is at the second level, the second switching element is turned off.

In this way, when the electronic device is in the standby state, the second control signal from the power supply control circuit is at the third level, and the oscillation switching circuit turns off the first switching element. As a result, the main power generation circuit stops the oscillation operation, so that the power consumption of the switching power supply device in the standby state can be reduced. At this time, the first control signal from the power supply control circuit is at the first level, the sub power supply generation circuit performs an oscillation operation, and a voltage as a power supply is supplied from the sub power supply generation circuit to the power supply control circuit. The power supply control circuit can operate.

When the electronic device is in a normal operation state, the second control signal from the power supply control circuit is the fourth.
The main power generation circuit oscillates and supplies a voltage as a power source to the load circuit of the electronic device. Further, since the voltage as the power source is supplied from the output voltage of the main power source generation circuit to the power source control circuit, the power source control circuit can operate. At this time, the first control signal from the power supply control circuit becomes the second level, and the oscillation switching circuit turns off the second switching element. As a result, the sub power supply generation circuit stops the oscillation operation, so that the power consumption of the switching power supply device in the normal operation state can be reduced, and the switching by the oscillation of the main power supply generation circuit and the sub power supply generation circuit can be achieved. It is possible to prevent an increase in noise level and an expansion of the frequency band of switching noise.

Further, when the oscillation operation of the sub power generation circuit stops, the oscillation operation of the sub power generation circuit stops after the first delay time after the main power generation circuit oscillates. Is not supplied from either the main power generation circuit or the sub power generation circuit, and the power supply control circuit can be prevented from stopping.

In addition, when the oscillation operation of the main power generation circuit stops, the oscillation operation of the main power generation circuit stops after the second delay time after the sub power generation circuit oscillates. Is not supplied from either the main power generation circuit or the sub power generation circuit, and the power supply control circuit can be prevented from stopping.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the oscillation switching circuit turns off the first switching element via the first optical coupling means and the second optical coupling means via the second optical coupling means. The switching element is turned off. According to this configuration, it is possible to insulate the power supply control circuit from the primary side of the main power supply generation circuit and the primary side of the sub power supply generation circuit.

According to a seventh aspect of the present invention, in any one of the second to sixth aspects, the power supply control circuit includes a microcomputer. According to this configuration, it is possible to easily output the control signal.

As described above, according to the present invention, power consumption can be reduced not only during standby but also during normal operation, and switching noise during normal operation can be reduced so as not to adversely affect other devices. A switching power supply device can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing an electrical configuration of a switching power supply according to an embodiment of the present invention. This switching power supply is used as a power supply for the TVCR, and supplies power necessary for the operation of the TVCR.

The switching power supply device shown in FIG. 1 generally includes a power supply control circuit 104 that has a microcomputer 100 and performs power supply control of a TVCR, and an input DC voltage VIN that is obtained by rectifying and smoothing an AC voltage from a commercial power supply (not shown). A main power generation circuit 101 that generates a voltage necessary for each part of the TVCR by switching, and the microcomputer 10 from the output voltage of the main power generation circuit 101
A microcomputer power supply circuit 1 that generates a voltage as an operating power of 0 and supplies the voltage to the microcomputer 100
03, a sub power generation circuit 102 that generates a voltage as an operation power source of the microcomputer 100 by switching the input DC voltage VIN, and a main power generation circuit 101 and a sub power generation circuit 102 based on a signal from the microcomputer 100 An oscillation switching circuit 105 that switches operation / stop of the oscillation operation is configured.

The main power generation circuit 101 includes a transformer 89 to which an input DC voltage VIN is applied, and a MOS FET to which the input DC voltage VIN is applied through a primary winding 89a of the transformer 89.
(Field effect transistor, hereinafter referred to as FET) 74 and 1 for causing the FET 74 to oscillate
A secondary circuit is provided, and by switching the voltage applied to the primary winding 89a of the transformer 89 by the oscillation operation of the FET 74, the secondary windings 89c, 89d, 8 of the transformer 89 are switched.
The voltage induced in 9e is supplied to each part of the TVCR.

First, the configuration of the primary side circuit will be described. One end of the primary winding 89a has an input DC voltage VI.
N is provided, and the other end of the primary winding 89 a is connected to the drain of the FET 74. Also,
The source of the FET 74 is connected to the ground via a Zener diode 71 and a resistor 72 connected in parallel, and is connected to the base of the transistor 78 via a diode 77. The gate of the FET 74 to which the input DC voltage VIN is applied via the resistor 70 is connected to the ground via a Zener diode 79, a capacitor 75, and a resistor 76 connected in parallel. Further, a capacitor 73 is connected between the drain and source of the FET 74.

The gate of the FET 74 is connected to the collector of the NPN transistor 78 and one end of the auxiliary winding 89b of the transformer 89 through a series circuit of the resistor 82 and the capacitor 83, and the other end of the auxiliary winding 89b. The emitter of the transistor 78 is connected to ground. The gate of the FET 74 is also connected to the oscillation switching circuit 105. The oscillation switching circuit 1
The connection with 05 and its operation will be described later.

The one end of the auxiliary winding 89b is connected to the base of the transistor 78 through a series circuit of a Zener diode 84 and a resistor 85, and is connected to the secondary side of the photocoupler 88 through a resistor 86 and a diode 87. It is connected to the collector of the phototransistor 88b. The emitter of the phototransistor 88 b is connected to the ground via the resistor 81 and is also connected to the base of the transistor 78. Further, the base of the transistor 78 is connected to the ground via the capacitor 80.

Next, on the secondary side of the transformer 89, a voltage + B is output from one end of the secondary winding 89c as a power source of a high voltage system circuit that generates a high voltage to be applied to the cathode ray tube of the TVCR. Further, a voltage P-ON + 9V as a power source for a 9V system circuit that requires 9V as an operating voltage is output from one end of the secondary winding 89d, and 12V as an operating voltage from one end of the secondary winding 89e. A voltage P-ON + 12V is output as a power supply for a 12V system circuit such as a necessary motor drive system circuit. 2 each
The other ends of the next windings 89c, 89d, and 89e are connected to a signal ground. The signal ground and the earth are connected via a capacitor 67.

A voltage + D as a power source for the deflection system circuit is output from a tap 89f provided at a predetermined position of the secondary winding 89c via a parallel circuit of a diode 90 and a capacitor 91. Further, a DC voltage obtained by rectifying and smoothing any voltage output from the secondary side of the transformer 89 is used as an F / B (feedback) voltage, and the light emitting diode 8 on the primary side of the photocoupler 88.
8a is given.

Next, the operation at the time of oscillation of the main power generation circuit 101 having such a configuration will be described. When a divided voltage obtained by dividing the input DC voltage VIN by the resistor 70 and the resistor 76 is applied to the gate of the FET 74 and the FET 74 is turned on, a current flows through the path of the primary winding 89a, the drain-source of the FET 74, and the resistor 72. Flows.

A voltage generated by the current flowing through the resistor 72 is applied to the base of the transistor 78 via the diode 77. When the transistor 78 is turned on, the collector potential of the transistor 78, that is, the gate potential of the FET 74 is L. Since it becomes (Low) level, the FET 74 is turned off. Since the FET 74 is turned off, the current does not flow, and the source potential of the FET 74, that is, the base potential of the transistor 78 becomes L level, so that the transistor 78 is turned off. When the transistor 78 is turned off, the divided voltage obtained by dividing the input DC voltage VIN by the resistors 70 and 76 is applied to the gate of the FET 74, and the FET 74 is turned on.

In this way, when the FET 74 is repeatedly turned on / off, a pulse current flows through the primary winding 89a, and the auxiliary winding 89b, secondary windings 89c, 89d, 8 are caused by this pulse current.
A voltage corresponding to each winding ratio is induced in 9e. For example, the secondary winding 89c has 12
A voltage of about 0V, a predetermined voltage between 20V and 30V is applied to the tap 89f, a voltage of about 9V is induced in the secondary winding 89d, and a voltage of about 12V is induced in the secondary winding 89e. The high voltage system circuit, the deflection system circuit, the 9V system circuit, and the 12V system circuit described above are supplied as operation power sources.

In addition, the DC voltage supplied from the secondary side of these transformers 89 is rectified and smoothed, and is supplied as an F / B voltage to the light emitting diode 88a on the primary side of the photocoupler 88.
The light emitting diode 88a is turned on when the F / B voltage exceeds a predetermined voltage.

When the light emitting diode 88a is turned on, the phototransistor 88b on the secondary side of the photocoupler 88 is turned on, and the voltage induced in the auxiliary winding 89b is applied to the base of the transistor 78 via the resistor 86 and the diode 87. become. Thereby, the transistor 7
Since 8 is turned on, the collector potential of the transistor 78, that is, the gate potential of the FET 74 becomes L level, so that the FET 74 is turned off, and the voltage induced in the secondary windings 89c, 89d, and 89e decreases.

When the F / B voltage becomes smaller than the predetermined voltage, the light emitting diode 88a is turned off,
Since the phototransistor 88b is also turned off, the voltage induced in the auxiliary winding 89b is not applied to the base of the transistor 78, and the transistor 78 is turned off. When the transistor 78 is turned off, the divided voltage obtained by dividing the input DC voltage VIN by the resistors 70 and 76 is applied to the gate of the FET 74, the FET 74 is turned on, and again as described above,
The FET 74 is repeatedly turned on / off.

In this way, feedback control is performed so that each voltage output from the secondary side of the transformer 89 becomes a predetermined voltage.

Next, the sub power supply generation circuit 102 will be described. The sub power generation circuit 102 includes a transformer 45 to which the input DC voltage VIN is applied, a FET 56 to which the input DC voltage VIN is applied via the primary winding 45a of the transformer 45, and a primary side circuit that causes the FET 56 to oscillate. FE
By switching the voltage applied to the primary winding 45a of the transformer 45 by the oscillation operation of T56, the voltage induced in the secondary winding 45c of the transformer 45 is rectified and smoothed, and supplied to the microcomputer 100 as a power source. Side circuit.

First, the configuration of the primary side circuit will be described. An input DC voltage VIN is applied to one end of the primary winding 45 a through a resistor 57, and the other end of the primary winding 45 a is connected to the drain of the FET 56. The source of the FET 56 is connected to the ground through a resistor 68, and is connected to the base of an NPN transistor 62 through a diode 59. The emitter of the transistor 62 is connected to the ground, and a capacitor 60 and a resistor 61 are connected in parallel between the base of the transistor 62 and the ground.

The gate of the FET 56 to which the input DC voltage VIN is applied via the resistors 64 and 65 is connected to the ground via the Zener diode 63 and is connected to the collector of the transistor 62. A capacitor 58 is connected between the gate and source of the FET 56. The gate of the FET 56 is also connected to the oscillation switching circuit 105.
The connection to the oscillation switching circuit 105 and its operation will be described later.

One end of the auxiliary winding 45b is connected to the connection point of the resistors 64 and 65 via the capacitor 66, and the other end of the auxiliary winding 45b is connected to the ground. The one end of the auxiliary winding 45b is connected to the collector of the secondary phototransistor 53b of the photocoupler 53 via a diode 55 and a resistor 54. The emitter of the phototransistor 53b is connected to the transistor 6
2 connected to the base.

Next, the configuration of the secondary side circuit will be described. One end of the secondary winding 45c is connected to the anode of the diode 44, the cathode of the diode 44 is connected to one end of the coil 41, and the other end of the coil 41 is connected to the power supply line ALL + 5V. Connected to signal ground. The other end of the secondary winding 45c is connected to a signal ground, and an electrolytic capacitor 43 and a Zener diode 42 are connected in parallel between the cathode of the diode 44 and the signal ground.

The cathode of the diode 44 is connected to the signal ground via a series circuit of resistors 48 and 49, and is connected to the anode of the light emitting diode 53 a on the primary side of the photocoupler 53 via the resistor 46 and the resistor 47. The shunt regulator 52 is connected to the cathode. The cathode of the light emitting diode 53a is connected to the cathode of the shunt regulator 52, and the anode of the shunt regulator 52 is connected to the signal ground. The connection point of the resistors 48 and 49 is connected to the reference terminal of the shunt regulator 52 and is connected to the cathode of the shunt regulator 52 through a series circuit of the resistor 50 and the capacitor 51.

Next, the operation at the time of oscillation of the sub power generation circuit 102 having such a configuration will be described. The cathode potential of the Zener diode 63 to which the input DC voltage VIN is applied via the resistors 64 and 65 becomes the Zener voltage of the Zener diode 63. When this voltage is applied to the gate of the FET 56 and the FET 56 is turned on, a current flows through the path of the resistor 57, the primary winding 45a, the drain 56 of the FET 56, and the resistor 68.

The voltage generated by the current flowing through the resistor 68 is applied to the base of the transistor 62 via the diode 59. When the transistor 62 is turned on, the collector potential of the transistor 62, that is, the gate potential of the FET 56 is L. Because it becomes a level, FE
T56 is turned off. Since the FET 56 is turned off, the current does not flow and FE
Since the source potential of T56, that is, the base potential of the transistor 62 becomes L level, the transistor 62 is turned off. When the transistor 62 is turned off, the Zener diode 6 again
3 Zener voltage is applied to the gate of the FET 56 and the FET 56 is turned on.

In this way, when the FET 56 is repeatedly turned on / off, a pulse current flows through the primary winding 45a, and the pulse current causes the auxiliary winding 45b and the secondary winding 45c to correspond to the respective winding ratios. A voltage is induced. Then, the voltage induced in the secondary winding 45c is rectified and smoothed by the diode 44 and the electrolytic capacitor 43 to become, for example, a DC voltage of 5V, and the pulsating current is further removed by the coil 41 and the electrolytic capacitor 40. , Supplied to the power line ALL + 5V.

A divided voltage obtained by dividing the output voltage of the capacitor 43 by the resistors 48 and 49 is given to the shunt regulator 52 as a reference voltage, and the shunt regulator 52 compares the divided voltage with the internal reference voltage to obtain a cathode. Determine the impedance between the anodes. Therefore, the potential of the cathode of the shunt regulator 52 changes according to the divided voltage, that is, the output voltage of the capacitor 43. This cathode potential is set so that the light emitting diode 53a of the photocoupler 53 is turned on when the output voltage of the capacitor 43 exceeds 5V, for example.

When the light emitting diode 53a is turned on, the phototransistor 53b on the secondary side of the photocoupler 53 is turned on, and the voltage induced in the auxiliary winding 45b is applied to the base of the transistor 62 through the diode 55 and the resistor 54. become. Thereby, the transistor 6
Since 2 is turned on, the collector potential of the transistor 62, that is, the gate potential of the FET 56 becomes L level, so that the FET 56 is turned off and the voltage induced in the secondary winding 45c decreases.

When the output voltage of the capacitor 43 decreases, the cathode potential of the shunt regulator 52 rises, the light emitting diode 53a is turned off, and the phototransistor 53b on the secondary side of the photocoupler 53 is also turned off, so that it is induced in the auxiliary winding 45b. The applied voltage is not applied to the base of the transistor 62, and the transistor 62 is turned off. When the transistor 62 is turned off, the Zener voltage of the Zener diode 63 is applied to the gate of the FET 56, the FET 56 is turned on, and the FET 56 is repeatedly turned on / off again as described above.

In this way, feedback control is performed so that the output voltage of the capacitor 43, that is, the DC voltage supplied to the power supply line ALL + 5V, becomes a predetermined voltage (for example, 5V) necessary for the operation of the microcomputer 100.

Next, the microcomputer power supply circuit 103 will be described. The microcomputer power supply circuit 103 generates a power supply voltage for operating the microcomputer 100 from the voltage + D supplied to the deflection system circuit and supplies it to the microcomputer 100.

One end of a resistor 16 is connected to a power supply line that supplies a voltage + D to the deflection system circuit, and the other end of the resistor 16 is connected to a signal ground via a parallel circuit of resistors 7 and 8 and a Zener diode 6. The NPN transistor 2 is connected to the collector of the NPN transistor 2 through one or three parallel circuits.

The cathode of the Zener diode 6 is connected to the NPN transistor 2 via the resistor 5.
The base of the transistor 2 is connected to the signal ground via the electrolytic capacitor 4. The emitter of the transistor 2 is connected to the signal ground via the electrolytic capacitor 17, the power line T + 5V connected to the memory backup power supply terminal Vcc 0 of the microcomputer 100 via the diode 18, and the diode 19. The power supply line ALL + 5V connected to the main power supply terminal Vcc of the microcomputer 100 is connected.

The operation of the microcomputer power supply circuit 103 having such a configuration will be described. When the main power generation circuit 101 is oscillating, a voltage + D, which is a predetermined voltage between 20 V and 30 V, is applied to the Zener diode 6 via the resistors 16, 7, and 8, and the cathode of the Zener diode 6 is The potential becomes the Zener voltage of the Zener diode 6. Then, this Zener voltage is applied to the base of the transistor 2 via the resistor 5, and a collector current corresponding to the difference between the base-emitter voltage of the transistor 2, that is, the difference between the Zener voltage and the output voltage of the electrolytic capacitor 17 flows. The electrolytic capacitor 17 is charged by this collector current.

As the electrolytic capacitor 17 is charged, the collector current decreases, and finally, the output voltage of the electrolytic transistor 17 is maintained at a predetermined voltage. The output voltage of the electrolysis transistor 17 is supplied to the power supply lines T + 5V and ALL + 5V via the diodes 18 and 19. Constants of each element constituting the microcomputer power supply circuit 103 such as a Zener voltage of the Zener diode 6 are set so that the voltages supplied to the power supply lines T + 5V and ALL + 5V are, for example, 5V.

Next, the power supply control circuit 104 will be described. The power supply control circuit 104 includes a microcomputer 100 that detects that a power-on operation has been performed with a remote controller attached to the TVCR and outputs a control signal for powering on the TVCR. The microcomputer 100 has a main power supply terminal Vcc to which an operation power is supplied, a memory backup power supply terminal Vcc0 to which a memory backup power is supplied, an output terminal H1 that outputs a control signal P-ON_H1, and a control signal P-ON_H2. An output terminal H2 for output is provided.

The main power supply terminal Vcc is connected to the power supply line ALL + 5V, and the memory backup power supply terminal Vcc0 is connected to the power supply line T + 5V. The output terminals H1 and H2 are connected to the oscillation switching circuit 105. The connection to the oscillation switching circuit 105, its operation, and the like will be described later.

The output terminal H1 is connected to the base of an NPN transistor 22 via a resistor 20, and the emitter of the transistor 22 is connected to a signal ground. A resistor 21 is connected between the base of the transistor 22 and the signal ground.

The collector of the transistor 22 is connected to the NPN transistor 12 via the resistor 14.
The emitter of the transistor 12 is connected to the signal ground. A resistor 15 and an electrolytic capacitor 13 are connected in parallel between the base of the transistor 12 and the signal ground.

The collector of the transistor 12 is connected to the base of the PNP transistor 9 via the resistor 11, the emitter of the transistor 9 is connected to a power supply line to which the voltage + D is supplied, and the collector of the transistor 9 is a microcomputer power supply circuit. 103 is connected to a connection point between the resistor 16 and the resistor 7. A resistor 10 is connected between the base and emitter of the transistor 9.

The operation of the power supply control circuit 104 having such a configuration will be described with reference to FIG. FIG. 2 is a waveform diagram showing waveforms of control signals P-ON_H1 and P-ON_H2 output from the microcomputer 100.
) Shows the waveform of the control signal P-ON_H2, and (b) shows the waveform of the control signal P-ON_H1. The control signals P-ON_H1 and P-ON_H2 are both binary signals that change to H (High) level / L (Low) level. For example, when the signal is H level, the voltage is about 5V. At the level, the voltage is about 0V.

In FIG. 2, the TVCR is in a standby state until time t1. At this time, the microcomputer 100
The control signals P-ON_H1 and P-ON_H2 are both set to L level. At time t1, for example, when a power-on operation is performed with a remote controller attached to the TVCR, the microcomputer 100 detects this by a detection circuit (not shown) and sets the control signal P-ON_H2 to the H level. The control signal P-ON_H1 is set to the H level at time t2 when a delay time T1 of several milliseconds has elapsed since that time. Note that the delay time T1 is the timing at which the control signals P-ON_H1 and P-ON_H2 are changed to the H level.
The reason why the time difference is provided will be described later.

When the control signal P-ON_H1 becomes H level at time t2, a voltage of about 5 V is applied to the base of the transistor 22 via the resistor 20, and the transistor 22 is turned on. When the transistor 22 is turned on, the base potential of the transistor 12 connected to the collector of the transistor 22 becomes L level, so that the transistor 12 is turned off. When the transistor 12 is turned off, the base potential of the transistor 9 connected to the collector of the transistor 12 becomes H level, so that the PNP transistor 9 is turned off. As a result, the current to the deflection circuit supplied from the emitter of the transistor 9 changes,
The deflection circuit rises and the TVCR enters a power-on state (normal operation state).

Next, when a power-off operation is performed, for example, with a remote controller attached to the TVCR at time t3, the microcomputer 100 detects this by a detection circuit (not shown) and the like, and the control signal P-ON_H
1 is set to L level, and the control signal P-ON_H2 is set to L level at time t4 when a delay time T2 of several msec has elapsed since then. The reason for providing the time difference of the delay time T2 at the timing of changing the control signals P-ON_H1 and P-ON_H2 to the L level will be described later.

When the control signal P-ON_H1 becomes L level at time t3, the transistor 22 is turned off. When the transistor 22 is turned off, the base potential of the transistor 12 connected to the collector of the transistor 22 becomes H level, so that the transistor 12 is turned on. When the transistor 12 is turned on, the transistor 9 connected to the collector of the transistor 12
Since the base potential of L is at L level, the PNP transistor 9 is turned on. as a result,
When the current to the deflection system circuit supplied from the emitter of the transistor 9 changes, the deflection system circuit is turned off, and the TVCR enters a power-off state (standby state).

Next, the oscillation switching circuit 105 will be described. The oscillation switching circuit 105 switches operation / stop of oscillation operations of the main power generation circuit 101 and the sub power generation circuit 102 in accordance with control signals P-ON_H1 and P-ON_H2 output from the microcomputer 100. Power generation circuit 101
A photocoupler 33 for transmitting a signal to the FET 74 and the FET 5 of the sub power generation circuit 102
6 has a photocoupler 37 for transmitting a signal. By using the photocoupler, the microcomputer 100 and the primary side of the main power generation circuit 101 and the sub power generation circuit 102 1
The secondary side can be insulated.

The collector of the phototransistor 33 b on the secondary side of the photocoupler 33 is connected to the gate of the FET 74 of the oscillation circuit 101 via the resistor 92, and the emitter of the phototransistor 33 b is connected to the ground via the resistor 93. The collector of the phototransistor 37b on the secondary side of the photocoupler 37 is connected to the FE of the sub power generation circuit 102 via the resistor 38.
Connected to the gate of T56, the emitter of the phototransistor 37b is connected to the ground via a resistor 39.

The anode of the light emitting diode 33a on the primary side of the photocoupler 33 and the anode of the light emitting diode 37a on the primary side of the photocoupler 37 are both power line ALL + 5V.
It is connected to the. Further, the cathode of the light emitting diode 33a is connected to the output terminal H2 of the microcomputer 100 and the signal ground via the resistor 32, and is connected to the base of the NPN transistor 29 via the resistor 31. The cathode
The collector of the NPN transistor 35 is connected.

The collector of the transistor 29 is connected to the power supply line ALL + 5V through the resistor 28 and the resistor 2
The signal ground is connected to the base of the NPN transistor 25 via the resistor 26, and the emitter of the transistor 29 is connected to the signal ground via the resistor 30.

The collector of the transistor 25 is connected to the power supply line ALL + 5V together with the collector of the NPN transistor 24, and the emitter of the transistor 25 is connected to the collector of the transistor 35 through the resistor 34 together with the emitter of the transistor 24.

The base of the transistor 24 is connected to the output terminal H2 of the microcomputer 100 via the resistor 23, the base of the transistor 35 is connected to the output terminal H1 of the microcomputer 100, and the emitter of the transistor 35 is connected to the signal ground via the resistor 36. It is connected to the.

The operation of the oscillation switching circuit 105 having such a configuration will be described with reference to FIG.
First, when the TVCR up to time t1 is in a standby state, that is, control signals P-ON_H1, P-ON_H2
When both are at the L level, the control signal P-ON_H1 is supplied to the base of the transistor 3
5 is turned off, and the transistors 24 and 29 to which the control signal P-ON_H2 is applied to the base are turned off. Since the transistor 29 is off, the transistor 25 is turned on, and the collector potential of the transistor 35 is substantially equal to the power supply line ALL + 5V.
No current flows through the light emitting diode 37a of the photocoupler 37, and the phototransistor 37b.
Is off. As a result, the FET 56 of the sub power supply generation circuit 102 repeats the on / off operation described above, and a voltage of 5 V is supplied from the sub power supply generation circuit 102 to the power supply line ALL + 5V.

On the other hand, in the photocoupler 33, since the control signal P-ON_H2 is at the L level, a current flows through the light emitting diode 33a, and the phototransistor 33b is turned on. As a result, the gate of the FET 74 of the main power supply generation circuit 101 becomes L level, and the FET 74 remains off. That is, since the main power generation circuit 101 has stopped oscillating, no voltage is supplied from the main power generation circuit 101 to each power supply line.

At this time, since no voltage is supplied from the main power generation circuit 101 to the microcomputer power supply circuit 103, the microcomputer power supply circuit 103 is in a state of not supplying voltage to the microcomputer 100. However, the microcomputer 100 includes a microcomputer power supply circuit 10.
In this state, the voltage supply from 3 is not received, but the voltage supply is supplied from the sub power supply generation circuit 102 via the power supply line ALL + 5V, and the circuit operates.

When the control signal P-ON_H2 becomes H level at time t1, the transistors 24 and 29 to which the control signal P-ON_H2 is applied to the base are turned on. The transistor 35 to which the control signal P-ON_H1 is applied to the base remains off. When the transistor 29 is turned on, the transistor 25 is turned off. However, since the transistor 24 is turned on, the transistor 35 is turned on.
The collector potential is substantially the same as that of the power supply line ALL + 5V. Accordingly, no current flows through the light emitting diode 37a of the photocoupler 37, the phototransistor 37b remains off, and the FET 56 of the sub power supply generation circuit 102 repeats the above-described on / off operation.
The voltage supply from the sub power generation circuit 102 to the power supply line ALL + 5V is continued.

On the other hand, since the control signal P-ON_H2 of the photocoupler 33 is at the H level, no current flows through the light emitting diode 33a, and the phototransistor 33b is turned off. As a result, the gate of the FET 74 of the main power generation circuit 101 is irrelevant to the state of the photocoupler 33, and the FET 74 repeats the on / off operation as described above, and the main power generation circuit 1.
The voltage starts to be output from 01. Since the voltage is supplied from the main power generation circuit 101 to the microcomputer power supply circuit 103, the power supply line ALL + 5V is supplied with a voltage of 5V from both the microcomputer power supply circuit 103 and the sub power supply generation circuit 102. Become.

The control signal P-ON_H1 is H at time t2 after a delay time T1 of several msec from time t1.
When the level is reached, as described above, the deflection system circuit rises and the TVCR enters the power-on state. At this time, the transistor 35 to which the control signal P-ON_H1 is applied is turned on, the collector potential of the transistor 35 becomes L level, a current flows through the light emitting diode 37a of the photocoupler 37, and the phototransistor 37b is turned on. As a result, the gate of the FET 56 of the sub power supply generation circuit 102 becomes L level, and the FET 56 remains off. That is, the sub power generation circuit 102 stops oscillating, and no voltage is supplied from the sub power generation circuit 102 to the power supply line ALL + 5V.

At this time, no voltage is supplied from the sub power supply generation circuit 102 to the power supply line ALL + 5V. However, since the main power supply generation circuit 101 oscillates and outputs voltage from the time t1, a microcomputer is connected to the power supply line ALL + 5V. Even if the voltage of 5 V is already supplied from the power supply circuit 103 and no voltage is supplied from the sub power generation circuit 102, the microcomputer 1
00 never stops. This is the reason why a time difference of several milliseconds, that is, a delay time T1 is provided at the timing of changing the control signals P-ON_H1 and P-ON_H2 to the H level.

When the control signal P-ON_H1 becomes L level at time t3, the state is the same as the period from time t1 to time t2. That is, since the control signal P-ON_H1 becomes L level, the deflection system circuit is turned off, and the TVCR enters a power-off state. Since the control signal P-ON_H1 is at the L level and the control signal P-ON_H2 is at the H level, the main power generation circuit 101 and the sub power generation circuit 102
Both of them oscillate, and the microcomputer power supply circuit 10 is connected to the power line ALL + 5V.
3 and the sub power supply generation circuit 102 are supplied with a voltage of 5V.

Then, the control signal P-ON_H2 becomes L at time t4 after several msec of delay time T2 from time t3.
When the level is reached, the state is the same as the period before time t1. That is, control signals P-ON_H1, P-ON_
Since both H2 are at the L level, the main power supply generation circuit 101 stops oscillating, the voltage output from the main power supply generation circuit 101 is not output, only the sub power supply generation circuit 102 oscillates, and the sub power supply generation circuit 102 supplies power. A voltage of 5V is supplied to the line ALL + 5V.

At this time, no voltage is supplied from the microcomputer power supply circuit 103 to the power supply line ALL + 5V. However, since the sub power supply generation circuit 102 oscillates and outputs a voltage from time t3, the power supply line ALL + 5V is supplied with the sub power supply line ALL + 5V. The voltage of 5 V has already been supplied from the power generation circuit 102, and the microcomputer 100 does not stop even if the voltage is not supplied from the microcomputer power supply circuit 103. This is the reason why a time difference of several milliseconds, that is, a delay time T2 is provided at the timing of changing the control signals P-ON_H1 and P-ON_H2 to the L level.

As described above, according to the present embodiment, the TV before time t1 and after time t4.
In the power-off state of the CR, the oscillation of the main power generation circuit 101 can be stopped and only the sub power generation circuit 102 can be oscillated, so that the power consumption of the switching power supply device in the power-off state can be reduced. At this time, since the voltage as the operation power supply of the microcomputer 100 is supplied from the sub power supply generation circuit 102 to the power supply line ALL + 5V that supplies the operation power supply of the microcomputer 100, the microcomputer 100 does not stop.

In addition, in the power-on state of the TVCR from time t2 to time t3, the oscillation of the sub power generation circuit 102 is stopped, so that the main power generation circuit 10 in the power-on state is stopped.
It is possible to prevent an increase in the level of switching noise and an increase in the frequency band of the switching noise due to the oscillation of both 1 and the sub power supply generation circuit 102. Further, by stopping the oscillation of the sub power generation circuit 102, the power consumption of the switching power supply device in the power-on state can be reduced.

In addition, while the oscillation of the main power supply generation circuit 101 is stopped, the power supply line ALL + 5V is supplied with a voltage of 5V as the operation power supply of the microcomputer 100 from the sub power supply generation circuit 102, and the oscillation of the sub power supply generation circuit 102. While the main power generation circuit 10 is stopped.
1 is supplied through the microcomputer power supply circuit 103 as a voltage of 5V as the operation power supply of the microcomputer 100, and the microcomputer 100 stops in the power-on state and the power-off state. There is nothing.

Further, when stopping the oscillation of the sub power generation circuit 102, the oscillation of the sub power generation circuit 102 is stopped after a delay time T1 of several milliseconds after the main power generation circuit 101 is oscillated, so that the power line ALL + 5V Furthermore, the voltage as the operation power supply of the microcomputer 100 is not supplied from either the main power supply generation circuit 101 or the sub power supply generation circuit 102, and the microcomputer 100 does not stop. The delay time T1 is several msec.
It is not limited to.

Further, when the oscillation of the main power generation circuit 101 is stopped, the oscillation of the main power generation circuit 101 is stopped after a delay time T2 of several milliseconds after the sub power generation circuit 102 is oscillated, so that the power line ALL + 5V Furthermore, the voltage as the operation power supply of the microcomputer 100 is not supplied from either the main power supply generation circuit 101 or the sub power supply generation circuit 102, and the microcomputer 100 does not stop. The delay time T2 is several mse.
It is not limited to c.

In this embodiment, the main power generation circuit 101 is supplied with a voltage as an operation power source of the microcomputer 100 via the microcomputer power supply circuit 103 to the power supply line ALL + 5V. Microcomputer 1 on the secondary winding of transformer 89
For example, a main power generation circuit 1 is provided by providing a tap for generating a voltage as an operation power supply of 00.
The voltage as the operation power supply of the microcomputer 100 may be directly supplied from 01 to the power supply line ALL + 5V.

In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it is also possible to change suitably the structure of each part, etc. and to implement.

1 is a circuit diagram showing an electrical configuration of a switching power supply device according to an embodiment of the present invention. It is a wave form diagram which shows the waveform of the control signal output from the microcomputer shown in FIG.

Explanation of symbols

33 Photocoupler (first optical coupling means)
37 Photocoupler (second optical coupling means)
45 transformer (second transformer)
45a Primary winding 45b Auxiliary winding 45c Secondary winding 56 FET (second switching element)
74 FET (first switching element)
89 Transformer (first transformer)
89a Primary winding 89b Auxiliary winding 89c, 89d, 89e Secondary winding 89f Tap 100 Microcomputer
101 Main power generation circuit 102 Sub power generation circuit 103 Microcomputer power supply circuit (control power supply circuit)
104 Power control circuit 105 Oscillation switching circuit

Claims (7)

A switching power supply that supplies power to an electronic device that can be switched between a normal operation state and a standby state,
The first and second control signals are output, and when there is an instruction to switch from the standby state to the normal operation state, the second control signal is changed from the third level to the fourth level. After the delay time of 1, the first control signal is changed from the first level to the second level, and when the switching instruction from the normal operation state to the standby state is issued, the first control signal is changed from the second level. A microcomputer having a function of changing to the first level and changing the second control signal from the fourth level to the third level after the second delay time;
A first series circuit including a primary winding of the first transformer and a first switching element and provided with an input DC voltage is provided, and the first transformer 2 oscillates by the oscillation operation of the first transformer.
A main power generation circuit that outputs a voltage induced in the next winding as a power source to the load circuit of the electronic device;
A control power supply circuit for supplying a new voltage generated from the output voltage of the main power generation circuit as a power source to the microcomputer;
A second series circuit including a primary winding of the second transformer and a second switching element to which the input DC voltage is applied; and a secondary of the second transformer by an oscillation operation of the second switching element. A sub power generation circuit for supplying a voltage induced in the winding as a power source to the microcomputer;
When the second control signal is at the third level, the first switching element is turned off via the first optical coupling means, and when the first control signal is at the second level, the second optical coupling means is turned off. Through the second
An oscillation switching circuit for turning off the switching element of
A switching power supply device comprising: A switching power supply that supplies power to an electronic device that can be switched between a normal operation state and a standby state,
A power supply control circuit that outputs a control signal to be changed based on a switching instruction between a normal operation state and a standby state;
A main power generation circuit that outputs a voltage obtained by switching an input DC voltage by an oscillation operation as a power source to the load circuit of the electronic device and the power control circuit;
A sub power generation circuit that supplies a voltage obtained by switching the input DC voltage by an oscillation operation as a power source to the power control circuit;
An oscillation switching circuit for stopping the oscillation operations of the main power generation circuit and the sub power generation circuit based on the control signal;
The oscillation switching block stops the oscillation operation of the main oscillation circuit when in a standby state, and the oscillation switching block stops the oscillation operation of the sub oscillation circuit when in a normal operation state. Further, the switching power supply device is characterized in that the control signal is changed. The switching power supply device according to claim 2, further comprising a control power supply circuit that supplies a new voltage generated from an output voltage of the main power supply circuit as a power supply to the power supply control circuit. The main power generation circuit includes a first series circuit including a primary winding of a first transformer and a first switching element to which the input DC voltage is applied, and is oscillated by an oscillation operation of the first switching element. Outputs the voltage induced in the secondary winding of the first transformer,
The sub power generation circuit has a second series circuit including a primary winding of a second transformer and a second switching element, to which the input DC voltage is applied, and is oscillated by the oscillation operation of the second switching element. 4. The switching power supply device according to claim 2, wherein a voltage induced in the secondary winding of the second transformer is output. The power supply control circuit outputs first and second control signals, and changes the second control signal from the third level to the fourth level when instructed to switch from the standby state to the normal operation state. Then, after the first delay time from that time, the first control signal is changed from the first level to the second level, and when there is an instruction to switch from the normal operation state to the standby state, the first control signal Is changed from the second level to the first level, and after that, after the second delay time, the second control signal is changed from the fourth level to the third level,
The oscillation switching circuit turns off the first switching element when the second control signal is at the third level, and turns off the second switching element when the first control signal is at the second level. The switching power supply device according to claim 4. The oscillation switching circuit turns off the first switching element via the first optical coupling means,
6. The switching power supply device according to claim 5, wherein the second switching element is turned off via the second optical coupling means. The switching power supply device according to claim 2, wherein the power supply control circuit includes a microcomputer.

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