JPH0962376A - Constant voltage power supply - Google Patents

Abstract

(57) Abstract: To provide a constant voltage power supply capable of supplying one or a plurality of different constant voltages capable of on / off control while achieving cost reduction and reliability improvement with a simple configuration. SOLUTION: A constant voltage output section Q11, Q12 which controls an input voltage to output a constant voltage, a control section which includes an emitter follower transistor Q11 and controls the constant voltage output section to output a constant voltage, and a constant voltage And a microcomputer IC1 having an output port P1 which is turned on / off based on the device to be supplied, the output port supplies a constant voltage as a reference voltage to the control unit (base of the emitter follower transistor Q11). The feature is that it is supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant voltage power supply capable of outputting one or a plurality of constant voltages whose ON / OFF can be controlled.

[0002]

2. Description of the Related Art In general, in electronic equipment, a plurality of constant voltage power supplies having different voltages are used depending on the property of each constituent block, and these voltages are often on / off controlled by a microcomputer or the like. Further, when controlling a device such as a solenoid used for a mechanism or the like, the holding voltage after that is often lower than the drive voltage at the time of turning on in order to reduce heat generation and power consumption. The constant voltage power supply in the present invention relates to a constant voltage power supply that can meet these requirements.

Conventionally, as an example of a constant voltage power supply that can meet the above requirements, there are those shown in FIGS. FIG. 5 is a circuit diagram showing a configuration of a conventional constant voltage power source using a Zener diode, FIG. 6 is a circuit diagram showing a configuration of a conventional constant voltage power source capable of on / off control, and FIG.
It is a circuit diagram which shows the structure of the constant voltage power supply for obtaining two voltages.

First, in the conventional constant voltage power supply using a Zener diode shown in FIG. 5, Vi is an input power supply voltage, D1 is a Zener diode as a reference voltage source, and Q is a reference voltage source.
Reference numeral 1 is a control transistor, R1 is a base resistance, C1 is an electrolytic capacitor, and V0 is an output voltage of the emitter.
In the constant voltage power supply configured as described above, as is well known, the output voltage V0 is made constant by keeping the base voltage of the control transistor Q1 constant.

Further, in the conventional constant voltage power supply capable of on / off control shown in FIG. 6, Vi is an input power supply voltage, Q2 and Q3 are switching transistors, Q4 is a voltage control transistor, and R2, R3, R4 and R6 are bases. Resistance, R
5 is a pull-up resistor, D2 is a Zener diode, C2
Is an electrolytic capacitor. Here, the switching transistors Q2, Q3 and the resistors 2, 3, 4, 5 constitute a switching circuit B1 for turning on / off the voltage supply to the Zener diode D2 constituting this constant voltage power source, and S1 is the switching circuit B1. Is a switch for turning on / off the supply of a voltage to.

Next, referring to FIG. 6, the operation of the above-mentioned constant voltage power source capable of on / off control will be described. First,
When the switch S1 is turned on, the switching transistors Q2 and Q3 are turned on, a voltage is supplied to the Zener diode D2, the voltage control transistor Q4 operates, and a constant voltage is output from its emitter. When the switch S1 is turned off, the switching transistors Q2 and Q3 are turned off, the voltage of the Zener diode D2 becomes 0, and the output of the voltage control transistor Q4 is turned off. In this way, the output of the constant voltage power supply can be turned on / off by turning the switch on / off.

In the conventional constant voltage power supply for obtaining two voltages shown in FIG. 7, Vi is the input power supply voltage, and B2
Is a constant voltage power source consisting of Zener diode, control transistor, base resistor and electrolytic capacitor, Q5, Q
6, Q7, Q8 are switching transistors, R2, R
3, R4 is a base resistor, R5 is a pull-up resistor, R7 is a voltage drop resistor, S _OL1 is a solenoid shown as an example of a utilization device that receives a constant voltage from this constant voltage power source, and S2 and S3 are switches.

Next, the operation of the constant voltage power supply for obtaining the above two voltages will be described with reference to FIG. First, when the voltage of the constant voltage power source B2 is stabilized, the switch S3 is turned off and the switch S2 is turned on, the switching transistors Q5 and Q6 are turned on and the switching transistors Q7 and Q8 are turned off.
_The voltage of the constant voltage power supply B2 is directly supplied to the OL1.

Next, when the switch S2 is turned off and the switch S3 is turned on, the switching transistors Q5,
Since Q6 is turned off and the switching transistors Q7 and Q8 are turned on, the voltage supplied to the solenoid S _OL 1 through the switching transistor Q8 is the solenoid S _OL 1
By the voltage drop resistor R7 connected in series with the voltage drop resistor, the voltage drop is lowered. As described above, this constant voltage power supply can inexpensively obtain two different types of voltage for driving the solenoid or the like by using the voltage drop resistor R7.

[0010]

However, when the conventional constant voltage power source configured as described above is used, the zener diode is used as the reference voltage in the constant voltage power source shown in FIG. 6, so that the cost is high. Moreover, when trying to obtain a plurality of constant voltages having different voltages, the number of zener diodes is required, which further increases the cost. Further, in the constant voltage power supply shown in FIG. 7, there is a problem that the circuit becomes very complicated and both cost and reliability are disadvantageous.

The present invention has been made in view of the above-mentioned conventional problems, and in order to overcome the drawbacks thereof, it is possible to reduce the cost and improve the reliability with a simple structure, and it is possible to control ON / OFF 1 or An object of the present invention is to provide a constant voltage power supply that can supply a plurality of different constant voltages.

[0012]

In order to achieve the above-mentioned object, the constant voltage power supply according to the present invention uses the port output voltage of one or a plurality of output ports of the microcomputer as it is as a reference voltage of the constant voltage power supply. It is characterized in that the output voltage of the constant voltage power source is changed by turning on / off the output voltage.

Further, in order to achieve the above object, the constant voltage power supply according to the present invention controls the input voltage and outputs a constant voltage (in the embodiment of the present invention, the voltage control transistor Q11, Q12, Q14, Q17, etc.), a control unit for controlling a constant voltage output unit so as to output a constant voltage including an emitter follower transistor, and a utilization device (solenoid etc.) for supplying a constant voltage. It is characterized by comprising a microcomputer having an output port set to ON / OFF, and supplying a constant voltage as a reference voltage from the output port to the control unit (base of the emitter follower transistor Q10). is there.

Further, in order to achieve the above object, the constant voltage power supply according to the present invention controls the input voltage and outputs a constant voltage (in the embodiment of the present invention, the voltage control transistor Q11, Q12, Q14, Q17, etc.), a control unit for controlling a constant voltage output unit so as to output a constant voltage including an emitter follower transistor, and a utilization device (solenoid etc.) for supplying a constant voltage. A microcomputer having a plurality of output ports individually set to ON / OFF, and a resistor connected in parallel to the control unit (base of the emitter follower transistor Q10) from each of the plurality of output ports, It is characterized in that the reference voltage for the control unit is changed by individually controlling ON / OFF of each output port.

In order to achieve the above object, the constant voltage power supply according to the present invention includes a ripple filter whose constant voltage output section is composed of a resistor and a capacitor, whereby the input voltage is lowered and the output voltage is set to the set voltage. Even in the following cases, there is an advantage that the fluctuation of the output voltage due to the ripple filter can be suppressed.

The constant voltage power supply according to the present invention is configured as described above, and thus does not use a Zener diode,
Instead, it is possible to easily and easily control ON / OFF by using a microcomputer having an output port that is set to ON / OFF based on the device used, and to supply one or more different voltages. A voltage power supply can be provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The first to fourth embodiments of the present invention will be described in detail below with reference to the accompanying drawings and FIGS. 1 to 4. 1 is a circuit diagram showing a configuration of a constant voltage power source according to a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a configuration of a constant voltage power source according to a second embodiment of the present invention, and FIG. FIG. 4 is a circuit diagram showing a configuration of a constant voltage power supply according to a third embodiment of the invention, and FIG. 4 is a circuit diagram showing a configuration of a constant voltage power supply according to a fourth embodiment of the present invention.

First, the configuration of the constant voltage power supply according to the first embodiment of the present invention will be described with reference to FIG. B3 is a constant voltage power supply that includes a Zener diode, a control transistor, a base resistor, an electrolytic capacitor, etc. and supplies a constant voltage (generally 5 V) to the microcomputer IC1, and the output port P1 of the IC1 is connected to the base of the emitter follower transistor Q10 A microcomputer for controlling the emitter follower transistor Q10, Q10 is an emitter follower transistor, and Q11 and Q12 are emitter follower transistors Q.
A voltage control transistor (which constitutes a constant voltage output section) connected to the collector of 10 and configured in Darlington, and the collectors of both voltage control transistors Q11 and Q12 are connected to the output. Further, R8 is a base resistance, R9 is a feedback resistance, and R10 is an emitter resistance. The output voltage V0 is connected to the emitter resistance R10 of the emitter follower transistor Q10 through the feedback resistance R9.

Next, the operation of the constant voltage power supply according to the first embodiment will be described with reference to FIG. Now, assuming that the output port P1 of the microcomputer IC1 is turned on and its voltage changes from 0V to 5V, the emitter voltage of the emitter follower transistor Q10 drops by about 1Vbe to about 4.3V. Then, a current starts to flow in the collector of the emitter follower transistor Q10 to turn on the voltage control transistors Q11 and Q12, and a voltage is output to the collector. Here, the output of the output port P1 (hereinafter,
Port output) is an emitter follower transistor Q1
The reason for receiving 0 is to reduce the current (hereinafter, referred to as port current) of the output port P1 of the microcomputer as much as possible and prevent the output voltage from decreasing.

On the other hand, when the output voltage V0 rises, the emitter voltage of the emitter follower transistor Q10 rises through the feedback resistor R9 and the emitter follower transistor Q1.
Since the base current and collector current of 0 decrease and the voltage control transistors Q11 and Q12 tend to turn off, the output voltage V0 tends to decrease. Then, the emitter voltage of the emitter follower transistor Q10 drops and balances to a constant voltage. At this time, the output voltage V0 is maintained in a constant voltage balance state.

Next, if the voltage at the output port of the microcomputer IC1 changes from 5V to 0V, the base voltage of the emitter follower transistor Q10 becomes 0V, so that its collector current does not flow and the voltage control transistor Q10.
Since 11 and Q12 are turned off, the output voltage becomes 0V. As described above, the microcomputer used in the present invention (the same one is used in all the embodiments) has one or more output ports and is controlled based on the control data written in the microcomputer in advance to output the port output voltage. Any one can be used as long as it can individually control ON / OFF.

The configuration of the constant voltage power supply according to the second embodiment of the present invention will be described below with reference to FIG. B3 is a constant voltage power supply having the same configuration and operation as the constant voltage power supply in the first embodiment, and IC1 receives a constant voltage (5 V) from the constant voltage power supply B3 and outputs a port output from its output port P1. A microcomputer Q14 connected to the base of the emitter follower transistor Q13 has its base connected to the collector of the emitter follower transistor Q13, and a voltage control transistor (which constitutes a constant voltage output section) Q15 for outputting an output voltage V0 from the collector, Q15. Has its emitter connected to the emitter resistor R11 together with the emitter of the emitter follower transistor Q13, and its base connected to the output voltage V0.
Is a voltage feedback transistor connected to the midpoint thereof by dividing the voltage by voltage setting resistors (voltage dividing resistors) R12 and R13.

Next, the operation of the constant voltage power supply according to the second embodiment will be described with reference to FIG. Now, if the output port P1 of the microcomputer IC1 is turned on and its voltage changes from 0V to 5V, the emitter voltage of the emitter follower transistor Q13 drops by about 1Vbe to about 4.3V. Then, a current starts to flow in the collector of the emitter follower transistor Q13, which turns on the voltage control transistor Q14 and outputs the output voltage V0 to the collector.

On the other hand, when the output voltage V0 rises, the voltage feedback transistor Q passes through the voltage setting resistors R12 and R13.
Since the base voltage and the emitter voltage of 15 increase and the base current and collector current of the emitter follower transistor Q13 decrease, the voltage control transistor Q14 tends to turn off and the output voltage V0 decreases. Then, the emitter voltage of the emitter follower transistor Q13 drops and balances to a constant voltage. At this time, the output voltage V0
Is maintained in a constant voltage balance state. In this case, the output voltage V0 is determined by the ratio of the voltage setting resistors R12 and R13 so that the base voltage of the voltage feedback transistor Q15 becomes about 5V.

Next, if the voltage of the port output of the microcomputer IC1 changes from 5V to 0V, the base voltage of the emitter follower transistor Q13 becomes 0V, so that its collector current stops flowing and the voltage control transistor Q13.
Since 14 is turned off, the output voltage V0 becomes 0V.

As described above, a constant voltage capable of on / off control can be obtained with a simple structure without using a Zener diode, and a P-type output transistor is used.
Since the NP transistor is used, voltage loss can be prevented even when the voltage is reduced.

The configuration of the constant voltage power supply according to the third embodiment of the present invention will be described below with reference to FIG. B3 is a constant voltage power supply having the same configuration and operation as the constant voltage power supply in the first embodiment, and IC1 receives a constant voltage (5 V) from the constant voltage power supply B3 and outputs a port output from its output port P1. A microcomputer connected to the base of the emitter follower transistor Q16, Q17 is a voltage control transistor whose base is connected to the collector of the emitter follower transistor Q16, and its collector output is fed through the feedback resistor R17 to the emitter follower transistor Q16.
Is connected to the emitter resistor R15.

Q18 is a voltage control transistor whose base is connected to the collector of the voltage control transistor Q17 and whose output voltage V0 is output from the emitter. The voltage control transistors Q17 and Q18 form a constant voltage output section. Further, R18 and C3 are a resistor and an electrolytic capacitor that constitute a ripple filter that suppresses fluctuations in the output voltage.

Next, the operation of the constant voltage power supply according to the third embodiment will be described with reference to FIG. Now, assuming that the output port P1 of the microcomputer IC1 is turned on and the voltage thereof changes from 0V to 5V, the emitter voltage of the emitter follower transistor Q16 drops by about 1Vbe to about 4.3V. Then, a current begins to flow in the collector of the emitter follower transistor Q16, which turns on the voltage control transistor Q17 and outputs a voltage to its collector. This increase in collector voltage raises the base voltage of the voltage control transistor Q18, and the output voltage V0 is output from the emitter of the voltage control transistor Q18.

On the other hand, when the output voltage rises, the output of the voltage control transistor Q17 raises the emitter voltage of the emitter follower transistor Q16 through the feedback resistor R17 and decreases the base current and collector current of the emitter follower transistor Q16. The emitter follower transistor Q16 is about to turn off, and the collector voltage of the voltage control transistor Q17 decreases. Then, the decrease in the collector voltage of the voltage control transistor Q17 lowers the emitter voltage of the emitter follower transistor Q16 through the feedback resistor R17 and balances it to a constant voltage. At this time, the base voltage of the voltage control transistor Q18 is stable, and the output voltage V0 from the emitter is held in a constant voltage balance state. In this case, the output voltage V0 is determined by the resistance ratio of the feedback resistor R17 and the emitter resistor R15 so that the emitter voltage of the emitter follower transistor Q16 becomes about 4.3V.

When the output voltage becomes lower than the set voltage due to the decrease of the input voltage, the voltage control transistor Q
17 is turned on, and a ripple filter including a resistor R18 and an electrolytic capacitor C3 suppresses fluctuations in the output voltage. However, in the first and second embodiments, the effect of suppressing the fluctuation of the output voltage by the ripple filter cannot be expected when the output voltage becomes equal to or lower than the set voltage due to the decrease of the input voltage.

The configuration of the constant voltage power supply according to the fourth embodiment of the present invention will be described below with reference to FIG. B3 is a constant voltage power supply having the same configuration and operation as the constant voltage power supply in the first embodiment, and B4 is a constant voltage power supply which may be any of the constant voltage power supplies in the first to third embodiments. So, Pi is the output port P of the microcomputer IC2
2, input ports for inputting port outputs from P3 (in the present embodiment, the emitter follower transistors Q10, Q13,
(Connected to the base of Q16), P0 is an output port of a constant voltage power supply, and S _OL1 is a solenoid shown as an example of a utilization device that receives a constant voltage from this constant voltage power supply.

Further, the microcomputer IC2 according to the present embodiment
Has two output ports P2 and P3, and is connected to the input port Pi of the constant voltage power supply B4 through two series resistors R20 and R21 having different resistance values connected in parallel to the output ports P2 and P3, respectively. . The resistance values of the two series resistors R20 and R21 may be any value, but the ratio in the present embodiment is R20: R2 for convenience.
1 = 2: 1.

Next, the operation of the constant voltage power supply according to the fourth embodiment will be described with reference to FIG. Now, 5V under control of the microcomputer IC2 which is set corresponding to the ON / OFF control of the solenoid S _OL 1 like using apparatus requires two output ports P2, P3 of the microcomputer IC2 is turned on, the voltage is from 0V 5V is input to the input port Pi of the constant voltage power supply B4. However, when the output port P3 is turned on to 5V and the output port P2 is turned off to 0V, the voltage 5V is divided by the ratio of the resistance values of the series resistors R20 and R21, and the constant voltage power supply B
2/3 × 5V is input to the input port Pi of 4.

On the other hand, when the output port P2 is turned on to 5V and the output port P3 is turned off to 0V, the voltage 5V is divided by the ratio of the resistance values of the series resistors R20 and R21, and the input port Pi of the constant voltage power source B4. Is input with 1/3 × 5V. Also, when both output ports P2 and P3 are off, 0
When it reaches V, 0V is input to the input port Pi.
Therefore, by controlling the on / off of the output ports P2 and P3, the reference voltage is set to 5V, 3.3V, 1.7V and 0V.
It is possible to change the output voltage to V and thereby to output four types of output voltage V including output ports P0 to 0V of the constant voltage power supply.
You can get 0.

In the present embodiment, four different reference voltages are created by on / off controlling the two output ports P2 and P3 of the microcomputer IC2, and four different constant voltages are obtained using the reference voltages. be able to. However, the number of output ports of the microcomputers IC1 and IC2 may be one or more.

[0037]

The constant voltage power supply according to the present invention is configured as described above, and in particular, by using a microcomputer without using the Zener diode which is conventionally provided for obtaining the reference voltage, ON / OFF control is possible with a simple configuration, and a constant voltage having one or a plurality of different voltage values can be supplied.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a constant voltage power supply according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a constant voltage power supply according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration of a constant voltage power supply according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a constant voltage power supply according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a constant voltage power supply using a conventional Zener diode.

FIG. 6 is a circuit diagram showing a configuration of a conventional constant-voltage power supply capable of on / off control.

FIG. 7 is a circuit diagram showing a configuration of a conventional constant voltage power supply for obtaining two voltages.

[Explanation of symbols]

Q1 control transistor Q2, Q3, Q5 switching transistor Q6, Q7, Q8 switching transistor Q4, Q11, Q12 voltage control transistor Q14, Q17, Q18 voltage control transistor Q10, Q13, Q16 emitter follower transistor Q15 voltage feedback transistor D1, D2 zener Diode R1, R2, R3, R4 Base resistance R6, R8, R14, R16 Base resistance R5 Pull-up resistance R7 Voltage drop resistance R9, R17 Feedback resistance R10, R11, R15 Emitter resistance R12, R13 Voltage setting resistance R18 Resistance R20, R21 series resistor C1, C2, C3 electrolytic capacitor S1, S2, S3 switches S _OL 1 solenoid B1 switching circuit B2, B3, B4 constant voltage power source Vi input supply voltage V0 Input port IC1 output ports P1, P2, P3 microcomputer output port Pi constant voltage power source B4 force voltage P0 constant voltage power source B4, IC 2 microcomputer

Claims (3)

[Claims] 1. A constant voltage output section for controlling an input voltage to output a constant voltage, a control section including an emitter follower transistor for controlling the constant voltage output section to output a constant voltage, and a constant voltage supply. A constant voltage power supply, comprising: a microcomputer having an output port that is turned on / off based on a device to be used, the output port supplying a constant voltage as a reference voltage to the control unit. 2. A constant voltage output section for controlling an input voltage to output a constant voltage, a control section including an emitter follower transistor for controlling the constant voltage output section to output a constant voltage, and a constant voltage supply. A microcomputer having a plurality of output ports that are individually turned on / off based on the device to be used,
A plurality of resistors connected in parallel to the control unit from each of the plurality of output ports, and by individually turning on / off each of the plurality of output ports, a reference voltage for the control unit is set. A constant voltage power supply characterized by being changed. 3. The constant voltage power source according to claim 1, wherein the constant voltage output unit includes a ripple filter including a resistor and a capacitor.