JP2003223229A - Stabilized power supply and electronic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent increase in cost by operating a power source of other system first with a less number of elements in a stabilized power supply. <P>SOLUTION: The stabilized power supply is to convert an input voltage Vin into a required voltage and supply the voltage Vin as an output voltage Vout to a load 10, and provided with a transistor 4 as a control means for controlling the input voltage Vin, and wherein a voltage of a power source 2 of the other system (voltage of the other system) is input and the voltage is used as an operation voltage of the transistor 4, so that the transistor 4 supplies the output voltage Vin to the load 10, after the power source 2 of the other system (voltage of the other system) was activated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilized power supply device which outputs an output voltage to a load after starting a power supply of another system by using a power supply voltage of another external system as a voltage of a control circuit.
And an electronic device equipped with the same.

[0002]

2. Description of the Related Art Recently, there are many kinds of elements such as LSIs that constitute electronic equipment, and the power supply voltage for operating these is not constant and extremely complicated.

For example, 12V, 9V, 5V, 3.3V,
There are devices that operate at 2.5V, 1.8V, 1.5V, etc.

In order to operate the electronic equipment in a stable manner, in addition to applying a predetermined voltage to each electronic equipment, it is necessary to adjust the order and timing of supplying the voltage to each element as described above. There is.

For example, for an LSI that needs to supply voltages of 3.3V and 2.5V, if 3.3V is first supplied and then 2.5V is not supplied, electronic devices including the LSI are required. The whole may malfunction.

Further, in an LSI that needs to supply voltages of 3.3V and 2.5V, the element may be destroyed if the state where only one voltage is supplied continues for a predetermined time or longer.

Further, in some memory devices, etc.,
It is necessary to supply two types of voltages of 12V and 5V. In this case, if 5V is first supplied and then 12V is not supplied, the element may be destroyed.

How to conventionally raise a plurality of power supply voltages will be described below with reference to FIGS. 6 and 7.

FIG. 6 is an explanatory diagram showing an example of a conventional power source startup sequence. According to the power generation sequence of FIG. 6, first, the power of 5V is turned on. Then, after a predetermined time Td1, the 3.3V power supply is turned on.

Further, after a predetermined time Td2, the power supply of 1.8V is turned on. In this way, the electronic device operates normally by turning on the plurality of power supplies in a predetermined order.

FIG. 7 shows an example of a circuit configuration for realizing the power supply startup sequence shown in FIG. According to the configuration example of FIG. 7, the microcomputer 31 controls the start timing of the two power sources, the second power source 32 that supplies the voltage of 3.3V and the third power source 33 that supplies the voltage of 1.8V. Controlled by.

As a result, each voltage is supplied to the CPU 34, which is a supply destination, according to the power supply start-up sequence of FIG. The microcomputer 31 has a power supply monitoring function.

That is, according to the configuration example of FIG. 7, when the first power supply 30 for supplying the voltage of 5V is started up, the voltage of 5V is supplied to the microcomputer 31, the second power supply 32, and the third power supply 3.
3 is supplied as an operating voltage, and each is in an operable state.

At this point, since the off command is still supplied from the microcomputer 31 to the second power source 32 and the third power source 33, no voltage is output from these power sources.

Time T has passed since the first power supply 30 started up.
When d1 elapses, the microcomputer 31 causes the second power source 3 to operate.
The ON command is supplied to the 2 (at this time, the OFF command is still supplied to the third power supply 33).

Upon receipt of this ON command, the second power source 32 supplies a voltage of 3.3V to the CPU 34.

Then, when the time Td2 further elapses, the microcomputer 31 supplies an ON command to the third power supply 33 (at this time, the second power supply 32 also receives the ON command. Up to.).

Upon receipt of this ON command, the third power supply 33 supplies a voltage of 1.8V to the CPU 34.

As described above, according to the configuration example of FIG. 7, the power supply start-up sequence of FIG. 6 can be realized, and 3.3V, when time (Td1 + Td2) has elapsed since the first power supply 30 started up, And two kinds of voltages of 1.8V are supplied to the CPU 34.

However, in the above-mentioned conventional technique, as described above, the power supply voltage of the elements such as the LSI constituting the electronic equipment is extremely complicated, and in order to operate the electronic equipment stably, each electronic equipment requires In addition to supplying the voltage, the device does not operate normally unless the required voltage is supplied to each element at the required timing.

Therefore, the power supply monitoring function required for the microcomputer controlling the system is complicated, and as a result, the cost of the microcomputer increases.

In addition, as long as the microcomputer for controlling the system is used to perform the power supply monitoring function, always, first,
It is necessary to start this microcomputer itself, and for that,
It is necessary to prepare a separate power supply for the above microcomputer (Fig. 7).
In this case, the first power supply 30 needs to be prepared separately. ).

For example, the operating voltage of the microcomputer controlling the system is set to 5 V, and the electronic device including this microcomputer has 5
Suppose there is another load operating at V. Furthermore, for stable operation of this electronic device, it is necessary to raise the power supply voltage of the other system before 5V. In such a case, 5V for the above microcomputer should be distinguished from the other loads mentioned above.
It is necessary to separately prepare the power supply voltage of, which causes a large cost increase.

In the power supply device disclosed in Japanese Patent Laid-Open No. 7-288928, a Zener diode having a power supply monitoring function is provided between the power supplies (for example, the second power supply 32).
And the third power supply 33) to adjust the power-up sequence of each of these power supplies.

However, even with this power supply device,
First, it is necessary to start the microcomputer itself, and for that purpose, it is necessary to separately prepare a power supply for the microcomputer.

Further, as one of the power supply devices capable of adjusting the power supply startup sequence of each power supply, for example, Japanese Patent Laid-Open No. 2000-2000
The power supply device disclosed in Japanese Patent Laid-Open No. 324808 can be mentioned. In this power supply device, an operation detection circuit having a power supply monitoring function is provided between each power supply (for example, between the second power supply 32 and the third power supply 33) to adjust the power supply startup sequence of each power supply. .

[0027]

To solve the problem of increasing the load on the microcomputer and the problem of having to provide a power source for the microcomputer, the applicant controls the system as shown in FIG. We have applied for a stabilized power supply device that does not increase the load on the microcomputer and that suppresses the cost of the microcomputer itself (Japanese Patent Application No. 2000-202785 (filing date: July 4, 2000); Unpublished at the time of confirmation).

Specifically, this stabilized power supply device has a power supply monitoring circuit for monitoring the voltage of the power supply of another system,
The activation can be actively controlled.

However, in this stabilized power supply device, since the power supply monitoring circuit is incorporated, the number of IC (integrated circuit) elements may increase and the chip size may increase. Therefore, the cost of the stabilized power supply device may increase.

Further, the power supply device disclosed in Japanese Unexamined Patent Publication No. 2000-324808 has an operation detection circuit having a power supply monitoring function provided between power supplies, so that the number of IC elements increases and the chip size also increases. Become. Therefore, the cost of the power supply device is increased.

Therefore, an object of the present invention is to provide a stabilized power supply device which can determine the starting order of power supplies with a smaller number of elements and which suppresses cost increase.

[0032]

In order to solve the above-mentioned problems, the stabilized power supply device of the present invention converts an input voltage into a required voltage under the control of a control means, and outputs this voltage as an output voltage to a load. In the stabilized power supply device to be supplied, the control means is characterized in that a voltage supplied from another system is used as an operating voltage.

According to the above invention, the input voltage is controlled by the control means and converted into a required voltage, which is supplied to the load as an output voltage.

The control means starts its operation when a voltage is supplied as an operating voltage from another system. In the stabilized power supply device, the input voltage is converted into a required voltage in accordance with the operation of the control means, and this is supplied to the load as an output voltage.

That is, according to the stabilized power supply device, even if the input voltage is supplied, the output voltage is not supplied to the load until the operating voltage is supplied to the control means from another system. . In this way, since the stabilized power supply device is actively started after the other system is started, it is not necessary to separately provide a power supply monitoring circuit (a circuit for monitoring the power supply of the other system) which is conventionally required. Therefore, it is possible to avoid cost increase due to an increase in the number of IC elements required for the power supply monitoring circuit and an increase in chip size.

Further, according to the above invention, since the input voltage and the operating voltage of the control means are supplied from different systems, the input voltage can be made smaller than the operating voltage of the control means. As a result, even when the low-voltage output voltage is supplied from the stabilized power supply device to the load, the power consumption of the stabilized power supply device can be significantly reduced.

Further, it is preferable that the stabilized power supply device further comprises delay means for delaying the voltage supplied from another system and supplying the delayed voltage to the control means as the operating voltage.

In this case, the voltage supplied from the other system is not directly supplied to the control means but is supplied via the delay means. Therefore, even if a voltage is supplied to the stabilized power supply device from another system, the operating voltage is not immediately supplied to the control means, but the operating voltage is supplied after the delay time.

As a result, the control means does not start its operation until a predetermined time (delay time) has elapsed since the other system was started. Therefore, the output voltage is supplied to the load after a lapse of a predetermined time (the delay time) from the activation of the other system. Therefore, for example, even when it is necessary to supply the output voltage to the load after a certain time or more has elapsed after the voltage of the other system is supplied, it is possible to cope with the situation.

Further, it is preferable that the stabilized power supply device further includes switching means for turning on or off by an external control signal, and the operating voltage is supplied to the control means via the switching means.

In this case, the control means does not operate only when the input voltage and the voltage of the other system are supplied to the stabilized power supply device, and therefore the output voltage is not supplied to the load. In addition to this, it is necessary to turn on the switching means by an external control signal in order to operate the control means.

This makes it possible to turn off (shut off) the switching means by the external control signal in case of emergency, etc., and avoid unnecessary supply of the output voltage to the load. Therefore, the reliability is significantly improved. At this time, the delay function by the delay means does not operate. Therefore, after the emergency cutoff, when the switching means is turned on again by the external control signal, the stabilized power supply device is immediately restarted.

Further, it is preferable that the delay means has a capacitor charged according to a time constant, and further comprises discharge means for discharging the capacitor when the supply of the voltage of the other system is stopped.

In this case, even when the stabilized power supply device is restarted or when the start-up off period is short, it is possible to ensure the necessary delay time and significantly improve the reliability.

When the stabilized power supply device is restarted, it can be restarted without any problem if no charge remains in the capacitor. However, when the electric charge remains in the capacitor, the time until the stabilized power supply device is activated is shortened by that much (the delay time of the delay means is shortened). This frequently turns on the regulated power supply,
This applies even when the turn-off period is short when turning off.

Therefore, according to the above configuration, when the supply of the voltage of the other system is stopped, the charge of the capacitor does not increase. At this time, since the capacitor is discharged by the discharging means, the electric charge remaining in the capacitor does not exist and the capacitor is in the initial state, so that the normal restart is performed with high accuracy. The capacitor is not discharged by the discharging means during and during the activation of the stabilized power supply device, so that the operation of the stabilized power supply device is not affected.

As described above, even when the voltage of the other system is once turned off and then restarted, or even when the start-up off period is short, the remaining charge of the capacitor is discharged through the discharging means. Therefore, normal startup can be performed stably and with high accuracy. In addition, the stabilized power supply device allows the startup sequence to be actively controlled by itself without increasing the load on the microcomputer controlling the system and increasing the cost. .

Further, the stabilized power supply device according to the present invention is a stabilized power supply device which converts an input voltage into a required voltage and supplies it as an output voltage to a load. Is input, and then the output voltage is supplied to the load. If a stabilized power supply device having such characteristics is incorporated in an electronic device, its reliability will be significantly improved.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] An embodiment of the present invention will be described with reference to FIGS. 1 and 2. The present invention is not limited to this.

The stabilized power supply device according to this embodiment will be briefly described. As shown in FIG. 2, the stabilized power supply device converts an input power supply into a required voltage and supplies its output voltage Vout to a load. In particular, the stabilized power supply device outputs the output voltage Vout after the power supply of the other system is activated by setting the voltage of the power supply of the other system (other system voltage) to the operating voltage of the control circuit.

FIG. 1 is a detailed description of FIG. As shown in this figure, the stabilized power supply device includes a transistor 3, a transistor 4, a comparator 5 (control means), a reference voltage generation circuit 6, a resistor 7, a resistor 8, and a capacitor 9. Then, an output voltage Vout is output from this stabilized power supply device.

1 and 2, an input power supply 1 and a power supply 2 of another system for supplying a voltage to the stabilized power supply device are also shown.

The stabilized power supply device includes the input power supply 1 to the load 1
The transistor 4 is interposed in the 0 power supply line. Then, the stabilized power supply device obtains a predetermined output voltage Vout by turning on / off the transistor 4.

In this stabilized power supply device, when the input voltage Vin is input from the input power supply 1, the output voltage Vout is supplied to the load 10 via the transistor 4.

The transistor 4 is turned on or off depending on the state of the load 10. As a result, the stable output voltage Vout is supplied to the load 10. The capacitor 9 is provided to stabilize the output voltage Vout.

Now, the control for turning on or off the transistor 4 will be described.

First, the voltage across the load 10 (load voltage)
Is divided by the resistors 7 and 8 and applied to the negative input terminal of the comparator 5.

The reference voltage Vref is applied to the positive input terminal of the comparator 5. The reference voltage Vref is generated by the reference voltage generation circuit 6.

The comparator 5 and the reference voltage generating circuit 6 use the voltage of the power supply 2 of the other system (power supply voltage of the other system) as the operating voltage. That is, the comparator 5 and the reference voltage generation circuit 6 start their respective operations only when supplied with the power supply voltage of the other system (other system voltage).

Then, for example, when the load voltage is smaller than the target output voltage Vout, the voltage applied to the minus input terminal of the comparator 5 becomes smaller accordingly. Therefore, this voltage becomes smaller than the reference voltage Vref, and the output of the comparator 5 becomes a positive voltage.
Along with this, the transistor 3 connected to the output terminal of the comparator 5 is turned on, so that the transistor 4 is turned on. This increases the load voltage.

On the other hand, when the load voltage is higher than the target output voltage Vout, the voltage applied to the negative input terminal of the comparator 5 increases accordingly. Therefore, this voltage becomes larger than the reference voltage Vref, and the output of the comparator 5 becomes almost the ground level. Along with this, the transistor 3 is turned off, so that the transistor 4 is also turned off. This reduces the load voltage.

As described above, by turning on or off the transistor 4, the target output voltage Vout is supplied to the load 10.

As described above, the power supply 2 of the other system supplies the other system voltage to the reference voltage generating circuit 6 to generate the reference voltage Vref. Then, this reference voltage V
The comparison between ref and the voltage division of the output voltage by the resistors 7 and 8 is performed by the comparator 5 supplied with the other system voltage.
When the voltage is output from the comparator 5,
The transistor 3 turns on, and then the transistor 4 turns on. As a result, the feedback system such as the comparator 5 and the reference voltage generation circuit 6 operates, and the stabilized power supply device is activated.

Unless the power supply 2 of the other system is activated, the output voltage Vout is not output even if the input voltage Vin is supplied. This is because the feedback system such as the comparator 5 and the reference voltage generation circuit 6 does not operate, that is, the transistor 4 remains off.

As described above, the stabilized power supply device itself can not output the output voltage Vout until the power supply 2 of the other system is activated (actively controlling the activation order by itself).

Therefore, in the above-described stabilized power supply device, it is not necessary to externally provide a microcomputer (system control microcomputer) for controlling ON / OFF of the stabilized power supply device as in the conventional case. In addition, a power supply, which has conventionally been required to be separately provided for the microcomputer, becomes unnecessary, so that cost increase can be suppressed.

Furthermore, the stabilized power supply device does not require a function (for example, a power supply monitoring circuit) of confirming that the power supply voltage of another system is activated. That is, there is no need to provide a power supply monitoring circuit. Therefore, the increase in the number of elements can be minimized. Therefore, it is possible to further reduce the cost of the stabilized power supply device by reducing the chip size.

Further, since the input voltage Vin and the operating voltage of the control circuit are respectively supplied from different systems, the input voltage Vin can be made lower than the operating voltage of the control circuit. Power can be significantly reduced.

[Second Embodiment] The following will describe another embodiment of the present invention with reference to FIG. Members having the same functions as those used in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The present invention is not limited to this.

In the stabilized power supply device shown in FIG. 3, the stabilized power supply device is activated when it is confirmed that a predetermined time has elapsed after the voltage of the other system was supplied from the power supply 2 of the other system. Has become.

As shown in FIG. 3, the power supply 2 of the other system supplies the voltage of the other system to the stabilized power supply device. A constant current source 11 (delay means), a capacitor 12
(Delaying means) is provided, and the comparator 5 and the reference voltage generating circuit 6 are connected to the connection point. In this respect,
The configuration is different from that of FIG.

In this case, another system voltage is supplied to the stabilized power supply device. The other system voltage from the other system power supply 2 is supplied to the constant current source 11 and the capacitor 12 connected in series. As a result, the constant current source 11 causes a constant current to flow toward the capacitor 12. Along with this, the capacitor 12 is charged with the constant current. After charging, this capacitor 12 supplies the other system voltage to the comparator 5 and the reference voltage generating circuit 6.

That is, even if the other system voltage is supplied from the power supply 2 of the other system to the stabilized power supply device, the operating voltage is not immediately supplied to the comparator 5 and the reference voltage generating circuit 6, and the operating voltage is delayed after the delay time. Will be supplied. for that reason,
The transistor 3 is turned on after a lapse of a predetermined time after the voltage of the other system is supplied, and then the transistor 4 is turned on.
Is also turned on.

When another system voltage is applied (supplied) to the constant current source 11 and the capacitor 12, the voltage at the connection point changes according to the time constant.

As described above, in the stabilized power supply device of the present embodiment, the transistor 2 must be activated until the power supply 2 of the other system is activated, that is, after a predetermined time has elapsed since the voltage of the other system was input. 4 never turns on. Therefore, if the voltage of the other system does not rise to the predetermined voltage within the predetermined time (delay time by the constant current source 11 and the capacitor 12) for some reason, the output voltage is not supplied to the load, which is very reliable. A stabilized power supply can be supplied.

[Third Embodiment] The following will describe another embodiment of the present invention with reference to FIG. Members having the same functions as those used in the first and second embodiments are designated by the same reference numerals, and the description thereof will be omitted. The present invention is not limited to this.

In the stabilized power supply device shown in FIG. 4, a transistor 13 (switching means) and an external terminal (on / off terminal) 14 are newly provided. In the transistor 13, the emitter is connected to each power supply terminal of the comparator 5 and the reference voltage generating circuit 6, and the collector is connected to the connection point between the constant current source 11 and the capacitor 12. The external terminal 14 is connected to the base of the transistor 13. This point is different from the configuration of FIG.

In this stabilized power supply device, the power supply 2 of another system is used.
The operating voltage of the control circuit is supplied after a lapse of a fixed time from the start of the voltage (other system voltage) from the power source and after the start command of the stabilized power supply device is input from the outside via the external terminal 14. It is supposed to be done. That is, even after a lapse of a predetermined time from the supply of the other system voltage, it is impossible to start the stabilized power supply device without a start command (external control signal) from the outside.

Therefore, even if the capacitor 12 is charged with the constant current from the constant current source 11, the transistor 13 is not turned on unless the activation command from the external terminal 14 is received. That is, in the configuration of FIG. 4, when the transistor 13 is turned on, all the starting conditions of the stabilized power supply device are satisfied.

As described above, when the transistor 13 is turned on, the other system voltage is supplied as the operating voltage of the comparator 5 and the reference voltage generating circuit 6, and these start operating. Then, as described above, the output voltage Vout is stabilized.

As described above, in the stabilized power supply device of this embodiment, the transistor 13 is turned on,
It is assumed that all the starting conditions are satisfied, and then the voltage of the other system is supplied to the comparator 5 and the reference voltage generating circuit 6 as the operating voltage, and the above feedback system operates, whereby the stabilized power supply device is started. In other words, the stabilized power supply device starts up only after satisfying the condition that the start command for outputting the output voltage to the load is supplied from the external terminal 14.

The stabilized power supply device shown in FIG.
In case of emergency, by turning off the start command from the external terminal 14, that is, by turning off the transistor 13, the stabilized power supply device can be surely turned off (cut off), and the load 10 of the output voltage Vout is turned off. It is possible to avoid unnecessary supply to the. Therefore, the reliability is significantly improved. At this time, the delay function by the constant current source 11 and the capacitor 12 does not operate. Therefore, after an emergency cutoff,
When the transistor 13 is turned on by the start command (external control signal), the stabilized power supply device is immediately restarted.

In the configuration of FIG. 4, the constant current source 11
Even if the configuration in which the capacitor 12 is removed and the collector of the transistor 13 is connected to the power supply 2 of another system, the same operation is achieved.

[Fourth Embodiment] The following will describe another embodiment of the present invention with reference to FIG. Members having the same functions as those used in the first to third embodiments are designated by the same reference numerals, and the description thereof will be omitted. The present invention is not limited to this.

In the stabilized power supply device shown in FIG. 5, a resistor 16 is provided between the power supply 2 of another system and the ground line, and the connection point between the constant current source 11 and the capacitor 12 and the resistor 16 are provided. A diode (discharging means) 15 is provided between the two. This point is different from the configuration of FIG.

This stabilized power supply device further has a function of discharging the electric charge accumulated in the capacitor 12, which ensures that the stabilized power supply device is restarted and the off period of the start command is short. It secures the required delay time and significantly improves reliability.

In the stabilized power supply device shown in FIG. 5, when the stabilized power supply device is restarted after it is turned off (the power supply 2 of the other system is also turned off), no electric charge remains in the capacitor 12. Sometimes it is possible to restart without problems.

However, when the electric charge remains in the capacitor 12, the time until the stabilized power supply device is activated becomes shorter by that much (the delay time becomes shorter). This applies even when the stabilized power supply device is frequently turned on and off and the start command has a short off period.

Therefore, according to the configuration of FIG. 5, when the power supply 2 / stabilized power supply device of another system is turned off, no current is output from the constant current source 11. ) Does not increase. At this time,
Since the voltage of the resistor 16 also becomes 0 (zero), the diode 1
The charge (remaining charge) accumulated in the capacitor 12 just before the turn-off of the diode 5 is turned on by the diode 15 and the resistor 16.
Be discharged through. As a result, the electric charge accumulated in the capacitor 12 does not exist, and the initial state is achieved, so that normal restart is performed with high accuracy.

The resistance value of the resistor 16 is set so that the voltage of the resistor 16 becomes higher than the voltage across the capacitor 12 during and during the activation of the stabilized power supply device. As a result, the diode 15 becomes non-conductive, and no charge moves from the capacitor 12 to the resistor 16. Therefore, the resistor 16 and the diode 15 do not affect the stabilized power supply device during startup and during startup.

Since the activation of the stabilized power supply device by the operation of the transistor 13 is the same as that described in the third embodiment, it is omitted here.

As described above, even if the stabilized power supply device and the power supply 2 of the other system are once turned off and then restarted, or restarted when the start command OFF period is short, they remain in the capacitor 12. Since the stored charge (remaining charge) is discharged through the diode 15 and the resistor 16, normal startup is performed stably and with high accuracy. In addition, the stabilized power supply device can internally actively control the starting sequence without increasing the load on the microcomputer (not shown) that controls the system.

In the configuration of FIG. 5, the transistor 13 and the external terminal 14 are removed, and the connection point of the constant current source 11, the capacitor 12 and the diode 15 is the comparator 5.
Even if it is connected to the reference voltage generating circuit 6, the same operation is achieved.

Further, in the above stabilized power supply device, the case where the PNP transistor is used as the transistor 4 is illustrated, but the present invention is not limited to this, and the present invention is also applicable to the case where the NPN transistor is used. The invention is applicable. Further, the present invention can be applied to a stabilized power supply device of a switching system.

Further, the stabilized power supply device according to the present invention (for example, the stabilized power supply devices of the first to fourth embodiments) converts the input voltage into a required voltage and supplies it as the output voltage to the load. The power supply device is characterized in that the output voltage is supplied to the load after the other system voltage is input therein. If a stabilized power supply device having such characteristics is incorporated in an electronic device, its reliability will be significantly improved.

The present invention can also be expressed as the following stabilized power supply circuit and electronic equipment.

The stabilized power supply circuit of the present invention is a stabilized power supply circuit which converts an input voltage into a required voltage and supplies the output voltage thereof to a load, and uses a voltage of another external system as a voltage of the control circuit. By doing so, the output voltage is output after the power supply of the other system is activated.

Further, in the stabilized power supply circuit of the present invention, after the power supply of the other system is started in the stabilized power supply circuit, the power is applied to the control circuit after a certain delay time and the output voltage is output. Is.

In the stabilized power supply circuit of the present invention, the stabilized power supply circuit is provided with an output voltage on / off function according to a control signal from the outside.

Further, the stabilized power supply circuit of the present invention is a stabilized power supply device having a delay function, in which the capacitor for setting the delay time is discharged when stopped.

Further, the electronic equipment of the present invention has a structure including the above-mentioned stabilized power supply circuit.

[0102]

As described above, the stabilized power supply device of the present invention converts the input voltage into the required voltage by the control of the control means and supplies this voltage as the output voltage to the load. The control means is configured to use a voltage supplied from another system as an operating voltage.

According to this, the input voltage is controlled by the control means and converted into a required voltage, which is supplied to the load as the output voltage.

The control means starts its operation when a voltage is supplied as an operating voltage from another system. In the stabilized power supply device, the input voltage is converted into a required voltage in accordance with the operation of the control means, and this is supplied to the load as an output voltage.

In other words, according to the stabilized power supply device, even if the input voltage is supplied, the output voltage is not supplied to the load until the operating voltage is supplied from the other system to the control means. .

As described above, since the stabilized power supply device is actively started after the other system is started up, a power supply monitoring circuit (a circuit for monitoring the power supply of the other system) which is conventionally required is additionally provided. Therefore, it is possible to avoid the increase in cost due to the increase in the number of IC elements required for the power supply monitoring circuit and the increase in chip size.

Further, according to the above invention, since the input voltage and the operating voltage of the control means are respectively supplied from different systems, the input voltage can be made smaller than the operating voltage of the control means. As a result, even when the low-voltage output voltage is supplied from the stabilized power supply device to the load, the power consumption of the stabilized power supply device can be significantly reduced.

Further, it is preferable that the stabilized power supply device further comprises delay means for delaying the voltage supplied from another system and supplying the delayed voltage as the operating voltage to the control means.

In this case, the voltage supplied from the other system is not directly supplied to the control means, but is supplied via the delay means. Therefore, even if a voltage is supplied to the stabilized power supply device from another system, the operating voltage is not immediately supplied to the control means, but the operating voltage is supplied after the delay time.

As a result, the control means does not start its operation until a predetermined time (delay time) has elapsed since the other system was started. Therefore, the output voltage is supplied to the load after a lapse of a predetermined time (the delay time) from the activation of the other system. Therefore, for example, even if the output voltage has to be supplied to the load after a certain time or more has passed after the voltage of the other system is supplied, it is possible to cope with the situation.

Further, it is preferable that the stabilized power supply device further includes switching means for turning on or off by an external control signal, and the operating voltage is supplied to the control means via the switching means.

In this case, the control means does not operate only when the input voltage and the voltage of the other system are supplied to the stabilized power supply device, and therefore the output voltage is not supplied to the load. In addition to this, it is necessary to turn on the switching means by an external control signal in order to operate the control means.

Thus, in case of emergency, the switching means can be turned off (cut off) by the external control signal, and unnecessary supply of the output voltage to the load can be avoided. Therefore, the reliability is significantly improved. At this time, the delay function by the delay means does not operate. Therefore, after the emergency cutoff, when the switching means is turned on again by the external control signal, the stabilized power supply device is immediately restarted.

Further, it is preferable that the delay means has a capacitor charged according to a time constant, and further comprises discharging means for discharging the capacitor when the supply of the voltage of the other system is stopped.

In this case, even when the stabilized power supply device is restarted or when the start-up off period is short, it is possible to ensure the necessary delay time and significantly improve the reliability.

When the stabilized power supply device is restarted, it can be restarted without any problem when no charge remains in the capacitor. However, when the electric charge remains in the capacitor, the time until the stabilized power supply device is activated is shortened by that much (the delay time of the delay means is shortened). This frequently turns on the regulated power supply,
This applies even when the turn-off period is short when turning off.

Therefore, according to the above configuration, when the supply of the voltage of the other system is stopped, the charged charge of the capacitor does not increase. At this time, since the capacitor is discharged by the discharging means, the electric charge remaining in the capacitor does not exist and the capacitor is in the initial state, so that there is an effect that normal restart is performed with high accuracy. The capacitor is not discharged by the discharging means during and during the activation of the stabilized power supply device, so that the operation of the stabilized power supply device is not affected.

As described above, even when the voltage of the other system is once turned off and then restarted, or even when the start-up off period is short, the residual charge of the capacitor is discharged through the discharging means. Therefore, normal startup can be performed stably and with high accuracy. Moreover, the stabilized power supply device has an effect that the startup sequence can be actively controlled by itself without increasing the load on the microcomputer controlling the system and increasing the cost.

Further, the stabilized power supply device according to the present invention is a stabilized power supply device which converts an input voltage into a required voltage and supplies it as an output voltage to a load. Is input, and then the output voltage is supplied to the load. If a stabilized power supply device having such characteristics is incorporated into an electronic device, the reliability of the device is significantly improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration example of a stabilized power supply device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram in which the configuration of FIG. 1 is simplified.

FIG. 3 is a circuit diagram showing a configuration example of a stabilized power supply device when the configuration of FIG. 1 has a delay function.

FIG. 4 is a circuit diagram showing a configuration example of a stabilized power supply device when the configuration of FIG. 3 is provided with an external starting function.

FIG. 5 is a circuit diagram showing a configuration example of a stabilized power supply device that can surely secure a necessary delay time even when the stabilized power supply device is restarted or when an off period of a start command is short.

FIG. 6 is a diagram showing an example of a conventional power source startup sequence.

7 is a circuit diagram showing a configuration example capable of realizing the power supply startup sequence shown in FIG.

FIG. 8 is a circuit diagram showing a configuration example of a stabilized power supply device that does not increase the load on a microcomputer that controls the system and suppresses the cost of the microcomputer itself.

[Explanation of symbols]

1 input power 2 Other system power supply 4 transistors 5 Comparator (control means) 6 Reference voltage generation circuit 10 load 11 Constant current source (delay means) 12 Capacitor (delay means) 13 Transistor (switching means) 14 external terminals 15 Diode (discharging means)

Claims (5)

[Claims] 1. A stabilized power supply device which converts an input voltage into a required voltage under the control of a control means and supplies this voltage as an output voltage to a load, wherein the control means operates a voltage supplied from another system. A stabilized power supply device characterized by being a voltage. 2. The stabilizing device according to claim 1, further comprising delay means for delaying the voltage supplied from another system and supplying the delayed voltage as the operating voltage to the control means. Power supply. 3. The stabilizing device according to claim 1, further comprising switching means for turning on or off according to an external control signal, wherein the operating voltage is supplied to the control means via the switching means. Power supply. 4. The delay means has a capacitor charged according to a time constant, and further comprises discharging means for discharging the capacitor when the supply of the voltage of the other system is stopped. The stabilized power supply device according to 2 or 3. 5. An electronic device comprising the stabilized power supply device according to claim 1.