JPH0580133U - DC power supply - Google Patents

Abstract

(57) [Abstract] [Purpose] A stabilized dual power source is formed with a simple, inexpensive, and compact configuration with a smaller number of parts than the conventional configuration using a constant voltage circuit IC or the like. [Structure] Two power operational amplifiers 7 and 8 connected to a non-inverting amplifier that outputs two stabilized power supplies and connected to an inverting amplifier, and output settings of both amplifiers 7 and 8 that are switched by binary change of control signal Reference input Vr for
And an output control switch (transistor Q5) for turning Vr 'on and off.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a DC power supply device which forms two power supplies such as a stabilized positive power supply and a negative power supply and turns on and off the output thereof according to a control signal.

[0002]

[Prior Art]

 2. Description of the Related Art Conventionally, in various electric and electronic devices such as a video device and an audio device, there is one in which the power supply from the DC power supply device is controlled by an external or internal control signal instead of a manual switch operation. A DC power supply device having a dual power supply output configuration to which this power supply control is applied has conventionally been configured using a constant voltage circuit IC as shown in FIG.

FIG. 1 shows a configuration in which two power sources of ± 5 V are formed with the reference potential as the ground potential. The secondary output of the power transformer 1 is rectified by the diodes D1 to D4 in the bridge connection and then 2 It is smoothed by two capacitors C1 and C2 provided between one end 1a and the tap 1t of the next winding and between the tap 1t and the other end 1b.

Positive and negative power supplies (input power supplies) are formed by this smoothing, and the positive and negative input power supplies are converted into constant voltages of +5 and -5 V by the two constant voltage circuits IC2 and IC3, respectively. A stabilized ± 5V power source (output power source) is formed, and both output power sources are sent to power transistors Q1 and Q2 serially inserted in the power feeding path via filter capacitors C3 and C4.

The both transistors Q1 and Q2 are provided with driver transistors Q3 and Q4 in the base circuit, and the binary conversion of the control signal supplied to the control terminal 4 causes the transistors Q1 and Q2 to pass through the transistors Q3 and Q4. Switches, and the output (supply) of the output power supply turns on and off.

That is, when the control signal is low level and the output is on, this signal is supplied to the base of the transistor Q3 through the resistor R5, the transistor Q3 is cut off, and the bias resistor R1 is turned on. A positive voltage is applied to the base of the transistor Q1 to turn on the transistor Q1.

Further, a voltage obtained by dividing the output of the emitter of the transistor Q1 and the output of the IC3 by the resistors R3 and R4 is supplied to the base of the transistor Q4. At this time, the resistors R3 and R4 become R3 <R4. For example, R3 = 68 KΩ and R4 = 100 KΩ are set. Based on this setting, the transistor Q4 is reversely biased and turned off, and the negative voltage via the biasing resistor R2 is applied to the base of the transistor Q2 to turn on the transistor Q2.

On the other hand, when the control signal goes high and the output is off, the transistor Q3 is turned on and the base of the transistor Q1 drops to the level of the ground terminal 5 (ground potential) connected to the tap 1t. Turn off. Further, the transistor Q4 is turned on by the output voltage of the IC3 via the resistor R4, and the base of the transistor Q2 also rises to the level of the ground terminal 5 and is turned off.

When the output is on, the outputs of the ICs 2 and 3 via the transistors Q1 and Q2 are smoothed by the capacitors C5 and C6 and sent to the positive and negative output terminals 6p and 6n, and both output terminals 6p and 6n. A stabilized ± 5V power source is generated between the ground terminal 5 and the ground terminal 5, and both power sources drive the electric and electronic devices.

Further, when the output is off, the transistors Q1 and Q2 are turned off, so that the positive and negative power supplies between the output terminals 6p and 6n and the ground terminal 5 disappear, and the power supply driving is stopped.

It should be noted that the ICs 2 and 3 are formed by a general constant voltage circuit IC, and control the power amplification unit of the power transistor configuration by the output of the operational amplifier according to the difference between the reference voltage of the constant voltage generation unit and the output voltage. Then, the output voltage is held at a constant voltage. Further, from the viewpoint of safety and circuit protection, this type of power supply device is formed by providing a thermal shutdown type short supply protection circuit, an overcurrent protection circuit, or a fuse in the ICs 2 and 3.

[0012]

[Problems to be solved by the device]

 In the case of the conventional power supply device shown in FIG. 3, two complicated and expensive constant voltage circuits IC2 and 3 are used to form a stabilized two power supply, and moreover, a capacitance is used for turning the output on and off by a control signal. Power transistors Q1 and Q2, and transistors Q3 and Q2 for their drivers, etc., are required, and there are problems that the number of parts is large, and the size is complicated, expensive, and large. An object of the present invention is to reduce the number of parts, and to provide a simple, inexpensive, and compact structure.

[0013]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the DC power supply device of the present invention, two power operational amplifiers of non-inverting amplifier connection and inverting amplifier connection, which output two stabilized power supplies respectively, and a binary change of control signal. It is equipped with an output control switch that switches on and off by turning on and off the reference input for setting the output of both power operational amplifiers.

[0014]

[Action]

 In the case of the direct-current power supply device of the present invention configured as described above, a power operational amplifier is used in place of the constant voltage circuit IC, and this operational amplifier does not have a constant voltage generating section of at least the constant voltage circuit IC. It is simpler and cheaper. Then, the power operational amplifier connected to the non-inverting amplifier and the power amplifier connected to the inverting amplifier form two stabilized power supplies based on the reference input for output setting.

Further, the control signal switches the input control switch to turn on / off the supply of the reference input to both power operational amplifiers, and the on / off switching turns on / off the outputs of both power operational amplifiers. The output of 2 power supplies can be turned on and off, and the output of 2 power supplies can be turned on and off without using a power transistor as in the past.

[0016]

【Example】

 One embodiment will be described with reference to FIGS. 1 and 2. In FIG. 1, the same reference numerals as those in FIG. 3 indicate the same or corresponding ones, and 7 and 8 are two power operational amplifiers provided in place of the ICs 2 and 3 of FIG. 3, and a series of positive and negative input power supplies. Synthetic power supplies are respectively supplied, the operational amplifier 7 is voltage follower connected to form a non-inverting amplifier connection, and the operational amplifier 8 is formed to an inverting amplifier connection using the output of the operational amplifier 7 as a reference input Vr 'for output setting. There is.

Reference numeral 9 is a reference input generator that supplies a non-inverting input terminal (+) of the operational amplifier 7 with a reference input V r of a constant voltage for output setting, and Q 5 is a transistor forming an output control switch, the base of which is a resistor. It is connected to the control terminal 4 via R6. R7 and R8 are resistors for setting constants of the operational amplifier 7, and R9 and R10 are resistors for setting constants of the operational amplifier 8.

The operational amplifiers 7 and 8 are formed by omitting the constant voltage generator from at least the ICs 2 and 3 of FIG. 3, and are simpler and cheaper than the ICs 2 and 3. Further, when generating an output power supply of ± 5V similar to that of FIG. 3, the reference input generation unit 9 forms the reference input Vr of + 5V.

Further, due to the change in the binary level of the control signal supplied to the control terminal 4, the transistor Q5 is turned off when the output is turned on and turned on when the output is turned off. When the output is turned on, the transistor Q5 is turned off to supply the reference input Vr to the non-inverting input terminal (+) of the operational amplifier 7. At this time, the operational amplifier amplifies the reference input Vr with a gain of 1 based on the voltage follower connection. To form a regulated positive power supply of + 5V.

Further, the + 5V output voltage of the operational amplifier 7 is supplied to the inverting input terminal (-) of the operational amplifier 8 as a reference input Vr 'for output setting, and at this time, the resistance values of the resistors R9 and R10 are set to be equal. Therefore, the operational amplifier 8 inverts and amplifies the reference input Vr 'by the gain 1 to form a stabilized negative power source of -5V.

Then, the ± 5V power supplies of the operational amplifiers 7 and 8 are supplied to the output terminals 6p and 6n via the capacitors C5 and C6, and a stabilized ± 5V power supply similar to the case of FIG. 3 is obtained. The electric power supply drives the electric and electronic devices.

Next, when the output is off, the transistor Q5 is turned on, so that the reference input Vr is not supplied to the operational amplifier 7, and the output of the operational amplifier 7 disappears and becomes zero. Further, due to this disappearance, the reference input Vr 'is not supplied to the operational amplifier 8 either, and the output of the operational amplifier 8 disappears to zero.

Therefore, the power supply of ± 5V is turned off, and the power supply drive of the electric and electronic devices is stopped. By the way, the stability of the output voltage of the operational amplifiers 7 and 8 depends on the reference input Vr.

In general, the input impedance of the operational amplifier 7 as viewed from the reference input generation unit 9 is high, and the input current of the operational amplifier 7 is normally in the unit of μA. Therefore, the reference input generation unit 9 is replaced with the conventional IC2. Even if a simple constant-voltage power supply with a Zener diode configuration as shown in FIG. 2 is used instead of a high-precision constant-voltage power supply such as the constant-voltage generator 3 of FIG. The fluctuations are extremely small, and the output voltages of the operational amplifiers 7 and 8 are stably maintained in the constant voltage state.

In FIG. 2, the Zener diode D5, the resistor R11, and the capacitor C7 form a constant voltage circuit that generates the reference voltage Vr, and the resistor R12 and the capacitor C8 form a low-pass filter that removes noise and ripple components. To do. This filter can be set according to the rising time constant of the input voltage of the operational amplifier 7. Further, a low-pass filter having a configuration different from that of the resistor R12 and the capacitor C8 may be used.

Since the reference input Vr is a minute current, the transistor Q5 for turning the output on and off may be of a small capacity for a small signal, and the output voltage of the operational amplifier 7 may be the reference input Vr of the operational amplifier 8. Therefore, it suffices to provide one transistor Q5 for turning the output on and off, resulting in a smaller number of parts and a simpler and smaller size than the configuration using the conventional transistors Q1 to Q4.

Note that the output of the operational amplifier 7 is used as the reference input Vr ′ of the operational amplifier 8 because the output impedance of the operational amplifier 7 is low, the stability is high, and the design is easy. This is because it has a strong advantage and is ideal as an input power source for the operational amplifier 8.

From the viewpoint of safety and circuit protection, it is desirable to deal with the output short circuit by using at least the operational amplifier 7 with a current limiting type and thermal shutdown type short supply protection circuit incorporated therein. In the above embodiment, the case where two power supplies of ± 5 V are formed has been described. However, it is a matter of course that two power supplies of various sizes can be formed by setting the reference input Vr and the resistors R7 to R10. Of the output + V and the output -V of the operational amplifier 8 are represented by the following [Equation 1].

[Equation 1] + V = Vr × (R7 + R8) / R8 −V = + V × R10 / R9

Further, the power operational amplifiers 7 and 8 may be respectively formed by a driver IC and an amplifier IC having an operational amplifier configuration. In this case, a fuse or the like may be provided to cope with the short output. Further, in the above-mentioned embodiment, the reference input generator 9 is provided to form the reference input Vr. However, when the electric and electronic equipment provided with this power supply device has a constant voltage power supply circuit, those constant voltage outputs are converted into resistors. It may be supplied as a reference input Vr to the operational amplifier 7 via the input signal Vr. In this case, the configuration is further simplified.

Further, although the output control switch is formed by the transistor Q5 in the above embodiment, it may be formed by a mechanical switch such as a relay switch which is switched by a control signal.

Further, in the above embodiment, the tap 1t is grounded via the ground terminal 5 to form the positive and negative power sources. For example, the other end 1b or the one end 1a of the secondary winding is grounded, and the tap 1t is grounded. It is also possible to form two positive or negative power sources using the potential of 2 as the reference potential. Further, it goes without saying that the forming circuit of the input power supply supplied to the operational amplifiers 7 and 8 may be different from that of the embodiment.

[0033]

[Effect of the device]

 Since the present invention is configured as described above, it has the following effects. Instead of the conventional two complicated and expensive constant voltage circuit ICs, two power operational amplifiers 7 and 8 with non-inverting amplifier connection and inverting amplifier connection, which are simpler and cheaper than this IC, are used. An output control switch (transistor Q5) is used in place of the power transistor or the like for each voltage circuit IC, and switching of this switch based on the control signal causes the reference inputs Vr and Vr 'for output setting to the operational amplifiers 7 and 8. Since the output of the stabilized two power supplies of the operational amplifiers 7 and 8 is turned on and off by turning the power supply on and off, a stabilized two power supply is formed with a simpler, cheaper and smaller configuration with fewer components than before. be able to.

[Brief description of drawings]

FIG. 1 is a connection diagram of an embodiment of a DC power supply device of the present invention.

FIG. 2 is a detailed connection diagram of a part of FIG.

FIG. 3 is a connection diagram of a conventional example.

[Explanation of symbols]

 4 Control terminal 7, 8 Power operational amplifier Q5 Transistor Vr, Vr 'as output control switch Reference input

Claims (1)

[Scope of utility model registration request] 1. Stabilized two power supplies having different polarities with respect to a reference potential are formed, and two of the supplied control signals are formed.
In a DC power supply device for turning on and off the outputs of the two power supplies according to a change in a value, two power operational amplifiers of a non-inverting amplifier connection and an inverting amplifier connection for outputting each of the two power supplies, and switching by a binary change of the control signal A DC power supply device comprising an output control switch for turning on and off a reference input for setting the output of both amplifiers.