JPH04207355A - Stabilized power supply circuit - Google Patents

Abstract

PURPOSE:To devise the power supply circuit to be hardly malfunctioned against pulse noise and to eliminate destruction of a semiconductor active switching element due to spike noise by providing a period in which a current passing through the semiconductor active switching element is decreased through the action of a current decrease means. CONSTITUTION:A diode 38 is provided between a power MOSFET 34 and a switching drive circuit 36 in this polarity. A diode 40 to apply a negative pulse generated in a current limit winding 32 to a gate of the power MOSFET 34 for a prescribed period is connected between the gate of the power MOSFET 34 and an intermediate tap of the current limit winding 32. Thus, the circuit hardly malfunctions against pulse noise and the element is not destroyed due to spike noise.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a DC power supply circuit used in electronic equipment.
In particular, by switching and smoothing the current,
This invention relates to a switching power supply circuit that can obtain stable DC voltage.

[Prior Art] A DC voltage is usually used for a power source in a power supply device. Commercial power supply (AC 100V, 5[JH2/60
Hz) has a waveform as shown in FIG. 7(a). This commercial power supply is rectified by a diode and is
) is the current with the waveform shown. By smoothing this rectified current with a capacitor,
) It is possible to obtain a DC voltage as shown in

Referring to FIG. 7(c), the DC voltage extracted in this manner includes a ripple component.

Furthermore, when another electronic device with a large load is connected to the commercial power source, the amplitude of the commercial power source shown in FIG. 7(a) fluctuates. This may cause the voltage value of the DC voltage to fluctuate as shown in FIG. 7(C). Since such fluctuations adversely affect the operation of electronic equipment, various methods are used to stabilize the DC voltage. This method is broadly divided into series regulators and switching regulators.

The most common example of a series regulator is one that uses a Zener diode. In this method, current is passed through a resistor and a Zener diode, and a Zener voltage is taken out as an output. However, this method is a drop type, and any excess current is dissipated as heat. As a result, it has the disadvantage of being inefficient and having an adverse effect on the circuit.

On the other hand, as shown in FIG. 9, a switching regulator divides the unstable voltage Vin into an ON part 74 and an OFF part 72 using some kind of switching means, and smoothes the divided parts to obtain a DC voltage. It is. ON
, by changing the time ratio of the OFF part,
Any stable output DC voltage can be obtained. Switching regulators are classified into various names depending on the ON/OFF opening/closing method. However, since they are all based on switching operation, they are collectively called switching regulators or switching stabilized power supplies.

According to this method, referring to FIG. 9, when the switching means is OFF, the current flowing is zero, and when the switching means is ON, the voltage is zero. Since the power consumption is P-VXI, ideally the power consumption of the switching stabilized power supply is 0.

However, referring to Fig. 10, in reality the voltage when ON is 0.
．． 7v~1. Ov, and both the voltage waveform and the current waveform are rounded, so that a point where the voltage waveform and the current waveform intersect occurs, as shown by diagonal lines in FIG. Therefore, heat is generated in this part of the switching regulator as well, and a certain amount of power is consumed. However, compared to the series regulator method mentioned above,
The switching regulator method is now widely used because it is lightweight, has a high-density design, and is easy to control.

FIG. 8 is a circuit block diagram of a power supply portion of a color television using a conventional switching stabilized power supply circuit. 8th
Referring to the figure, the power supply circuit of this color television consists of a water q = oscillation circuit 10, a horizontal excitation circuit 12, a horizontal output circuit 14, and a commercial power source for obtaining the water 14 output (Fig. 11), which will be described later. Unstable DC voltage 26 obtained by rectification and intermediate layering, horizontal output circuit] 4 and unstable DC voltage 2
6 and is connected to the flyback transformer 16 for boosting the waveform output from the underwater output circuit 14;
A diode for rectifying the waveform boosted to high voltage by 6] and a diode 18 connected to the distributed capacitance 2
2 and a flyback transformer 1.
A diode 66 for rectifying the waveform boosted to small/medium voltage by the diode 66, a small/medium voltage device 68 driven by the waveform rectified by the diode 66, a flyback transformer 16, an unstable DC voltage 26, A conventional stabilizing power supply circuit 62 is connected to a conventional stabilizing power supply circuit 62 for converting the unstable DC voltage given from the unstable DC voltage 26 into a stable DC voltage and supplying it to the primary coil of the flyback transformer 16 as an excitation power source. including.

Horizontal output waveform (11th
The output shown in the figure is necessary for scanning the water I of the cathode ray tube 20 in one direction. Referring to FIG. 11, the interval between the horizontal output underwater pulses 78 is determined as follows: 1! j (corresponds to a 4" scanning period. The period during which the water 3'1' pulse 78 lasts corresponds to the necessary period (retrace period) to reach the base line of the scan or the beginning of the next scan.

A high voltage is required to cause the electron beam to reach the fluorescent surface of the emission knee 2 and the Braun shield 20 from the cathode of the cathode ray tube 20. This voltage is 5. For example, a 21-inch cathode ray tube (4) has a voltage of about 25 KV. This high voltage can be obtained by using the horizontal output. As shown in Fig. 11, the water output circuit is The waveform obtained from 4 has a pulse C with a peak value of about 900 V. This pulse is applied to the flyback transformer coil W, IIL2, and the pulse C with a higher peak value to the conical secondary coil. This output is given by the diode]8 and the cathode ray tube 20/))
By rectifying the current with the canister foot 22, the equation 1-
A high pressure of KV can be obtained.

+ ゛l'-l car, cathode ray tube 2 with tunj' beam
It is also used for underwater and L inspections of 0. In this case, Water 1' No. 9 is flyha! In addition to rito1, s]0, figure・),
The deflection that is not applied is increased by 1 point. Is there a deflection current necessary for scanning in the underwater direction due to resonance between the laser and the laser? Being photographed.

Old Figure 8 2 lights, 2, flyback transformer 16
One end is connected to the output of the horizontal output circuit 1.5, the other end is connected to the stabilizing voltage 192 circuit 62, and the female voltage is connected to the output of the horizontal output circuit 1.5. +f circuit 62
A current reduction winding 28 for exciting the secondary winding of the tractor controller 10 with a horizontal output is installed on the secondary side. 71i, which is electromagnetically coupled with the current reduction winding 28, and is electromagnetically coupled with the high voltage secondary wire 30 for outputting the front pressure, and which is electromagnetically coupled with the current reduction winding 28, and is A small/medium voltage secondary winding 58 for supplying a predetermined voltage signal to the medium voltage equipment 68, one end of which is stable 11'j current +-+: 26 d, and the other end of which is stable (L ;ti);' are connected to the circuit 02, respectively, and the unstable DC forces 1. ．． I: includes a current limiting winding 32 for limiting changes in the current flowing from I. 26 to the stabilized power supply circuit 62.

The stabilized power supply circuit 02 has an anode or a current limiting winding 32.
The cathodes are each connected to a current reduction winding 28, and a 5CR (Sil
icon Convrollea Rectifi
er) 64, a smoothing capacitor 42 connected between the cathode of the 5CR64 and the ground, and for smoothing the output voltage of the 5CR64, the output of the 5CR64, and the 5CR64.
and the secondary coil 58 for small/medium voltage,
5CR64 output voltage and secondary winding 58 for medium voltage
The control circuit 08 includes a control circuit 08 that generates a control signal for turning 5CR64 ON-OFF so that its output voltage becomes a constant voltage in response to the voltage obtained from the voltage.

5CR64 has the properties of a diode in which current flows from the anode to the cathode. The 5CR64 becomes conductive when a pulse is applied to its gate terminal, even if the voltage is below a certain pressure required for conduction.

Furthermore, 5CR64 has the property of continuing to conduct (self-retaining action) if it becomes electrically conductive. In order to stop the conduction of 5CR64, a reverse voltage may be applied between the anode and the cathode.

5CR64 performs the switching function as described above.

By using this switching function, unstable DC voltage 26
Opens and closes the electric current rE (approximately 130V) given by 1.1
The role of the stabilizing power supply circuit 62 is to generate a constant power of 10V. The voltage output from 5CR64 and smoothed by the smoothing capacitor 42 and the specified 11
Detects the error between 0 V and 5C according to the difference.
By controlling the timing of applying a pulse to the gate 1 terminal of R64, a constant voltage can be obtained as the output of the stabilized power supply circuit 02.

Referring to FIG. 12, a control circuit 90 is connected to the cathode of 5CR64, outputs from 5CR64, and 1-
An error gB between the voltage smoothed by the Namekawa capacitor 42 and a predetermined voltage ci1nv) is detected, and error 1.
It is connected to the error detection circuit 80 for outputting -1, the small/medium voltage secondary winding 58, and the error detection circuit 80, and the horizontal output excites the small/medium voltage secondary winding 58. An integrating circuit 84 is connected to the integrating circuit 84 and the error detecting circuit 80, and is connected to the integrating circuit 84 and the error detecting circuit 80, and a voltage applied from the integrating circuit 84. A slice pulse shaping circuit 8 for generating a gate pulse to be applied to the gate of 5CR64 by slicing the value at a predetermined voltage value.
2.

The error detection circuit 80 includes a resistor and an rJJ variable resistor VR connected in series between the cathode of the 5CR64 and the ground potential.
and a transistor Q1 whose base is coupled to a variable resistor VR to detect the error between the output voltage of the 5CR64 and a predetermined voltage; and a transistor Q2 for amplifying.

Integrating circuit 84 includes a capacitor C1 and a resistor R1.

One end of the resistor R] is connected to a contact point between the secondary winding 58 and the diode 66. Capacitor C] is connected between the other end of resistor R] and ground potential. A contact between the resistor R1 and the capacitor HC] is connected to the emitter of the transistor Q2 via the resistor.

The slice pulse shaping circuit 82 includes a Zener diode 88 provided between the emitter of the transistor Q1 and ground, a transistor Q3 whose base is connected to a contact point between a resistor R1 and a capacitor C1, and a transistor Q3 connected from the emitter of the transistor Q3 to the transistor Q. ) connected in the forward direction toward the emitter of the diode 86. The slice pulse shaping circuit 82 further includes a transistor Q4 whose base is connected to the collector of the transistor Q3, and a transistor Q4.
It includes a resistor R3 and a capacitor gC2 connected in series between the emitter of 5CR64 and the gate of 5CR64.

Referring to FIGS. 7 to 14, a color television power supply circuit using a conventional stabilized power supply circuit operates as follows. Horizontal oscillation circuit 10, horizontal excitation circuit 12, horizontal output circuit] 4 provides a horizontal output as shown in FIG. 11 to current reduction winding 28. The small/medium voltage secondary winding 58 is electromagnetically coupled to the current reduction winding 28, so in response to this horizontal output, it generates a flyback pulse as shown in FIG. 13(a) for control purposes. It is applied to the integrating circuit 84 of the circuit 90. The flyback pulse shown in FIG. 13(a) is the first
The one with the opposite polarity to the horizontal output in Figure 1 is the small
This is because the winding direction of the intermediate voltage secondary winding 58 is selected in such a direction.

The transistor Q1 of the error detection circuit 80 detects the error between the cathode voltage of the 5CR64, that is, the output voltage of the stabilized power supply circuit 62, and a predetermined voltage (11, OV), and sends a signal corresponding to the error to the transistor Q2. Give to the base.

Transistor Q2 amplifies this error signal and connects it to integrator circuit 8.
Give to 4.

The integrating circuit 84 integrates the flyback pulse given from the secondary winding 58 (Ml 3 (b)), and
It is superimposed on the DC component of the error amplified output from transistor Q2 (see the solid line in FIG. 13(C)).

The output of integration circuit 84 is applied to the base of transistor Q3 of slice pulse shaping circuit 82.

The waveform input to the base of the transistor Q3 is sliced by the voltage Vz determined by the Zener diode 88, and the waveform shown by the solid line in FIG. 13(d) is obtained at the collector of the transistor Q3.

This signal is amplified by transistor Q4 and then differentiated by a differentiating circuit consisting of capacitor JIAC2 and resistor R3. As a result, a gate pulse having a waveform shown in FIG. 13(e) is obtained.

This gate pulse is input to the gate of 5CR64.

When this pulse is applied, the 5CR64 turns on and increases the current until a negative voltage is input to the anode. The negative voltage applied to the anode is provided in response to the horizontal output by electromagnetic coupling between the current reducing winding 28 and the current limiting winding 32.

Consider a case where the output voltage of the stabilized power supply circuit 62 fluctuates. When the output voltage increases, the base voltage of transistor Q increases. Therefore, the collector current of the transistor Q1 increases, and the collector voltage of the disabling transistor Q1 decreases. Since the voltage superimposed in the integrating circuits 8 and 1 decreases, the integrated waveform drops as shown by the broken line in FIG. 13(c). As a result, the point sliced by the tuner diode 88 moves on the time axis. The period during which the collector voltage of transistor Q3 decreases is also shortened. 5, as shown by the dotted line in FIG. 13(e), it moves after the point in time when 5CR64 is turned on. When the 5CR64 is turned off, the I claw is determined by the horizontal output, so the anode voltage of the 5CR64 decreases. As a result, the charging current to the 10' Namekawa capacitor 42 is reduced, and as a result, the output voltage of the stabilized power supply circuit 62 is controlled to be constant.

The operation of the 5CR64 will be explained with particular reference to FIGS. 8 and 14. As mentioned above, the waveform at the output point A of the horizontal output circuit 14 in FIG. 8 is as shown in FIG. 14(a). The waveform at the output point B of the tertiary winding 58 is the first waveform as shown in FIG. 13(a).
The waveform shown in FIG. 4(a) is inverted.

When a gate pulse as shown in Fig. 14(b) is applied to the gate of 5CR64, the 5CR
64 turns on. An anode current begins to flow through 5CRb4. However, 2, unstable DC voltage 26 and 5CR6
Since the current limiting winding 32 is connected in series between the current limiter and the current limiter 4, the increase in the current is limited and gradually increases.

When the horizontal pulse reaches V1 as shown in FIG. 14(a), the anode voltage begins to decrease.

When the anode voltage reaches a negative peak as shown in FIG. 14(C), the 5CR64 is turned off.

In this way, the anode voltage superimposed on the reversed horizontal pulse is turned off by the gate pulse shown in FIG. 14Cb) and turned off by the negative pulse of the anode voltage itself. the result,
The anode current shown in Figure 14(d) flows through the SCR64, and the "output voltage" in Figure 14(C)
A voltage portion reduced to 1 is taken out and smoothed by 1' by an intermediate slipping codenser 42, so that a constant DC voltage can be obtained.

[Invention or problem to be solved] Conventional stabilized power supply circuits use SCRs.

The SCR is driven by a pulse applied to the gate.

Therefore, there is a problem that pulse noise is applied to the gate, making it easy to malfunction. Also, if the SCR in a conventional circuit is replaced with another semiconductor active element, the ON
There was a problem in that spike noise was generated when switching from to OFF, and the device was destroyed.

Therefore, it is an object of the present invention to prevent malfunctions caused by pulse noise and to prevent spike noise.
175. Stabilization without risk of device destruction. The purpose is to provide a source circuit.

[Means for Solving the Problems] A stabilized power supply circuit according to the present invention includes an input terminal, an output terminal, and a control terminal, and is connected to the input terminal or an unstable DC power supply, and the stabilized power supply circuit includes an input terminal, an output terminal, and a control terminal.゛↓, conductor active switching means for switching on and off the current between the input terminal and the output terminal in response to a control signal manually applied to the terminal;
．． The conduction D of the semiconductor active switching element is provided to be connected between the source and the semiconductor active switching element.
), a current limiting means for limiting fluctuations in the current flowing through the semiconductor active switching element f; A current reduction means for reducing the flowing current, a smoothing means for smoothing the voltage output from the output terminal of the ``+'' conductor active switching element and converting it into a DC voltage, and an L smoothing means. a control means for setting a control signal to a control terminal for controlling the semiconductor active switching element in response to the smoothed DC voltage, depending on the magnitude of the predetermined voltage and the smoothed DC voltage; 4. Means for relaxing control No. 1.3 for a predetermined period including when the conductor active switching element is interrupted; include.

[Function] In the stabilized power supply circuit 1 and 1 described above, a period tHt is provided in which the current passing through the conductor active switching element decreases due to the action of the current reducing means. When the control means outputs a control signal for turning off the semiconductor active switching element during the second period, this control signal is relaxed. Therefore, the current flowing through the semiconductor active switching element is not interrupted instantaneously.

[Embodiment] FIG. 1 shows a stabilized power supply circuit 24 according to an embodiment of the present invention.
2 is a block diagram of a color television power supply circuit.

In FIG. 1, the intermediate voltage secondary winding 58, which is smaller in FIG. 8, is omitted to simplify the illustration.
There is. The difference between the circuit shown in FIG. 1 and the circuit shown in FIG. 8 is that a stabilized power supply circuit 24 according to the present invention is included in place of the conventional stabilized power supply circuit 64. 1st
Identical parts are given the same reference numbers and names in the figures and FIG. Their functions are also the same. 1. The detailed explanation of C1 is repeated here, but please refer to Fig. The source is coupled through a diode 44 and connected to one end of the train or current reduction winding 28.
SFET34 and power MO8FET-34 train and connection 11i! connected between the potential and the power MOS
For smoothing the voltage output by FET 34: J: is connected to the decimeter 42 and the power MO3FET 34 train, and is intermediated by ``1'' and Namekawa capacitor 42). A control for detecting an error between a DC voltage and a predetermined negative voltage (for example, ]0 to ') and controlling the power MOSFET '44 in response to this error is controlled by a power MO8FET. '340 and a switching drive circuit 36 for supplying the gate.

Between the power h10 SFET-34 and the switching drive circuit 36, there is a diode F'' (8 or
Connected in the J direction. Between the power MO5FET 340 gate L and the midpoint of the current limiting winding 32, a negative pulse generated by the current limiting winding 32 is connected to the power M
A diode 40 is connected to the gate of the O8FET 34 for applying voltage for a certain period of time.

As shown in FIG. 2, the power MOSFET of FIG.
34 can be replaced with a transistor 34a. Referring to FIG. 2, the emitter of this transistor 34a is connected to a diode 44. The collector is connected to one end of the current reduction winding 28. The base is connected to the switching drive circuit 36 via a diode 38 and to the midpoint of the current limiting winding 32 via a diode 40.

The stabilized power supply circuit 24 shown in FIG. 1 and the stabilized power supply circuit 24a shown in FIG. 2 operate in exactly the same way.

In the following, the operation of this stabilized power supply circuit will be explained according to FIG. 2 to simplify the explanation. Transistor 34a is a PNP type transistor. The transistor '34a is [7. It becomes conductive when the emitter voltage is higher than the current voltage to C1, and current flows from the emitter to the current.

This current is called collector current.

Referring to FIG. 3, the horizontal output (a) and the emitter voltage (b) of transistor 34a are equal to the horizontal pulse (FIG. 14(a)) and the anode voltage ( This is the same as in FIG. 14(C)). Further, the base control voltage (FIG. 3(d)) applied from the switching drive circuit 36 to the base of the transistor 34a is the same as that of the transistor Q of the conventional device shown in FIG. 13(d).
By a circuit similar to the circuit for obtaining the collector voltage in 3.
) r f$ can be -C.

This base control voltage turns the transistor 34a into
By turning off the transistor 34a, a collector current having a waveform shown in FIG. 3(e) flows through the transistor 34a. This operation is almost the same as that using the conventional SCR shown in FIG. However, the stabilized power supply circuit 24a according to the present invention has the following points #F.
t'6j1. There is.

In this transistor 34a, the base is connected to the midpoint of the zti flow nr11 limited line 32 via the diode 4(-). The potential in this part is the same as that in the decreasing part of the collector current shown in Fig. 3(e).
As shown in e), the voltage drops below the emitter voltage. Therefore, in this section, the switching drive circuit 36
Even if an attempt is made to disconnect the transistor 34a by the base control voltage shown in FIG. 3(d), the result shown in FIG. 3(C) is
Because of the voltage drop indicated by , current flows from the emitter of transistor 34a to the base, through diode 40, and to current-limiting winding 32.

Therefore, even when the switching drive circuit 36 shuts off the transistor 34a, the current is not instantaneously cut off. There is no risk of spike noise occurring at the collector of the transistor 34a.

As is well known, spike noise is larger when switching from ON to OFF'F than when switching from OFF to ON.

This means that the applied voltage is instantaneously disconnected.
This is because the circuit also has a transient response characteristic, so a phenomenon occurs in which the output does not oscillate greatly but converges to 0. Shigonika τ, from ON to O as above
By quickly causing the current from the emitter to flow elsewhere during switching to the FF, the possibility of spike noise occurring in the collector is reduced.

Since the base control voltage output from the switching drive circuit 36 has the property of being driven by a constant voltage applied to the base of the transistor 34a,
) may be any rectangular wave as shown in . Further, in this case, the switching drive circuit 36 includes the transistor 34 a
Any circuit that allows current to flow from the base of the circuit is sufficient.

In this way (this switching element is transistor 3)
4a (or power MO5FE134), the signal for driving the switching element may be a rectangular wave as described above. Unlike when using a conventional SCR, if pulse nature or noise is applied to the base of the runnostar, 1. There is also no risk that the transistor 343 will malfunction. Therefore, it is possible to provide a stabilized power supply circuit that can operate stably.

FIG. 4 is a circuit block diagram of a color television power supply circuit using a stabilized power supply circuit 46 according to a second embodiment of the present invention. The circuit shown in FIG. 4 is different from the circuit shown in FIG. A stabilizing power supply circuit 46 is connected to the unstable DC voltage 26 to supply a stable DC voltage to the current reduction winding 28. Figures 1 and 4
Identical parts have been given the same reference numerals and names in the figures. Their functions are also the same. Therefore, a detailed explanation of them will not be repeated here.

Referring to FIG. 4, the stabilizing voltage circuit 4e consists of a voltage source connected to one end of the current-reducing winding 28 and a drain connected to one end of the current-limiting winding 32 via a diode 44. rNo Mo S F E T 52 and power,, M
A smoothing capacitor 42 is connected between the source of the OS FET 52 and the ground potential to smooth the source voltage of the power MO8FET"52, and the power MO5
Connected to the source of FET 52, smoothing capacitor 42
In response to the error between the DC voltage smoothed by 2 and a predetermined voltage (for example, 110V),
Switching drive circuit 4 for applying a control voltage for switching to the gate of ET 52 via diode 50
8, the power MO5FET 52 is connected between the gate of the power MO5FET 52 and the midpoint of the current reduction winding 28, and in response to a main pulse applied to the current reduction winding 28, the power MO5FET
and a bias circuit 54 for applying a positive voltage to the gate of 52 for a certain period of time.

Bias circuit 54 includes a diode 60 and a resistor 56 connected in series between the midpoint of current reduction winding 28 and the gate of power MO3FET 52.

FIG. 5 shows a stabilized power supply circuit 46a in which the power MO8FET 52 shown in FIG. 4 is replaced with an NPN type transistor 52a. In Figure 4 and Figure 1), are the same parts labeled with the same pentagrams and names? 7 I'm looking forward to it. Their functions are also the same. Therefore, the operation of the apparatus shown in FIG. 5 will be described below for the sake of brevity.

The horizontal output applied from the horizontal output circuit 14 to the main current reduction winding 28 has the waveform shown in FIG. 6(a) as in the first embodiment. The collector voltage of the transistor 52a becomes as shown in FIG. 6(b). This is a waveform similar to that of the emitter voltage in the first embodiment (Fig. 3(b)).

)・Since the transistor 52 (a) is of the NPN type, the l\-base drive voltage output from the switching drive circuit 48 is equal to the base voltage in the first embodiment, as shown in FIG. 6(d). The polarity is opposite to that of the driving voltage. The second base drive voltage is a DC voltage smoothed by a smoothing capacitor 42 and a predetermined voltage (
Depending on the error from 110V), the attractive voltage is 1.1 or 11 (I
Vr: Controlled by the switching drive line 48 so as to approach.

When the horizontal output shown in FIG. 6C is applied to the current reduction winding 28, a bias voltage as shown in FIG. or is applied. (When the base drive voltage is switched from ON to OFF during this period,
Similar to the third embodiment, the current is not interrupted instantaneously. (1) In this stabilized power supply circuit 46a (46), the drive voltage output from the switching drive circuit 48 is a rectangular wave. Even if pulse noise is applied to the base (or gate) of the transistor 52a (power MO5FET 52), there is no risk of the stabilized power supply circuit malfunctioning. It is possible to provide a stabilized power supply circuit that can be used in various ways.

The above description has been based on an embodiment in which the present invention is applied to a power supply circuit for a color television. [,.

However, the present invention is not limited to the embodiments described above, but can also be applied to other electrical equipment.

[Effects of the Invention] As described above, according to the present invention, when the control signal for turning off the semiconductor active switching element r is outputted by the control signal, this control signal is relaxed.

Therefore, the current flowing through the semiconductor active switching element is not instantaneously interrupted. There is no risk of spike noise being generated from the semiconductor active switching device, and a stable DC voltage can be obtained without the risk of destroying the device. Furthermore, since a semiconductor active switching element is used, a rectangular wave is used as a control signal. S
Unlike conventional stabilized power supply circuits using CR, pulses are not used to control switching elements.

Therefore, the stabilized power supply circuit according to the present invention is strong against pulse noise and can generate a stable DC voltage.

As a result, it is less likely to cause malfunction due to pulse noise.
<>, and it is possible to provide a stabilized power supply circuit in which the element r is not destroyed by spike noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a power supply circuit for a color television using a stabilized power supply circuit according to the present invention, FIG. 2 is a circuit block diagram of a main part of a modification of FIG. 1, and FIG. FIG. 4 is a waveform diagram for explaining the operation of the first embodiment of the present invention, and FIG. 4 is a block diagram of a color television power supply circuit using the stabilized power supply circuit according to the second embodiment of the present invention. 5 is a block diagram of a main part of a modified example of the circuit shown in FIG. 4, FIG. 6 is a waveform diagram for explaining the operation of the second embodiment, and FIG. FIG. 8 is a circuit block diagram of a color television using a conventional stabilized power supply circuit; FIG. 9 is a conventional switching stabilized power supply circuit. FIG. 10 is a schematic waveform diagram showing the power consumption of the switching stabilized power supply circuit, FIG. 11 is a waveform diagram of horizontal output, and FIG. FIG. 1 is a block diagram of an SCR control circuit of a conventional stabilized power supply circuit, and FIGS. 13 and 14 are waveform diagrams showing the operation of the conventional stabilized power supply circuit. In the figure, 16 is a flyback transformer, 24.24a, 4
6.46a is a stabilized power supply circuit, 26 is an unstable DC voltage,
28 is a current reduction winding; 32 is a current limit winding; 34.
52 is a power MO5FET, 34a and 52a are transistors, 36.48 is a switching drive circuit, 40 is a bias diode, 42 is a smoothing capacitor, and 54 is a bias circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Patent Applicant: Sharp Corporation 1, - Fig. 3 A7.4 [;') Fig. \n') C)shi≦)4gu,'#chi8 Figure, / 16 zO Figure q>JIO Shizu, City)j, %>'M Figure 11 Figure 12 Shij 1311 (e)' 7 Tonoguru suit\--: 2-←14th Shi1 (b) 4〆1 Nog12 and --♂ Knee

Claims (1)

[Claims] (1) The input terminal includes an input terminal, an output terminal, and a control terminal, and the input terminal is connected to an unstable DC power source, and the input terminal and a semiconductor active switching element for intermittent current between the output terminal and the semiconductor active switching element, the semiconductor active switching element being connected between the DC power supply and the semiconductor active switching element, and when the semiconductor active switching element is conductive, the semiconductor active switching element current limiting means for limiting an increase in current flowing through the active switching element; and current limiting means coupled to the current limiting means for reducing the current flowing through the semiconductor active switching element in response to an externally applied current reduction signal. current reducing means; smoothing means for smoothing the current output from the output terminal of the semiconductor active switching element and converting it into a DC voltage; ,
a control means for applying a control signal to the control terminal for controlling the semiconductor active switching element according to the magnitude of a predetermined voltage and the smoothed DC voltage; and a control means connected to the control terminal; a predetermined period of time including at least a time when the semiconductor active switching element is cut off by the control means in response to the current reduction signal;
and means for moderating the control signal.