JP2005312157A - Dc stabilized power supply apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dc stabilized power supply apparatus which can attain a reduced power consumption and which can use an output capacitor of small capacity. <P>SOLUTION: The DC stabilized power supply apparatus includes an output transistor 3, a control circuit 4 for controlling the output transistor 3, an additional unit having an overcurrent protecting circuit 10, an overheat protecting circuit 9 and a soft starting circuit 8 to control the output transistor 3 irrespective of the output of the control circuit 4, a load state detector circuit 18 which determines whether a load 17 is a standby state having smaller power consumption than normal to output its determined result, and a power supply breaking circuit 19 which stops the power supply to the additional unit when the load 17 is in a standby state according to the output of the load state detector circuit 18 and which supplies a power to the additional unit when the load 17 is not in a standby state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stabilized DC power supply device.

  2. Description of the Related Art Conventionally, a stabilized DC power supply device has been widely used to supply a stable DC voltage to a load regardless of fluctuations in input voltage or load, or changes in the surrounding environment. In recent years, devices equipped with digital circuits, such as computers and AV devices, are rapidly spreading, and in these devices, a stabilized DC power supply is indispensable.

  The DC stabilized power supply device uses a dropper type DC stabilized power supply device that maintains the output voltage by dropping the voltage by using the output transistor as a kind of variable resistor, and the ratio of the ON time and the OFF time of the switching element (duty The switching type DC stabilized power supply device that keeps the output voltage stable by controlling the ratio). In the former dropper type DC stabilized power supply device, the input voltage is dropped and the output voltage is stabilized, so that the drop is released as heat. For this reason, the efficiency is not particularly good when the voltage difference between the input and output is large, but there is an advantage that the design is easy and the generated noise is small, so that the application is not easily limited. On the other hand, the latter switching type DC stabilized power supply device switches the switching element and controls its duty ratio to stabilize the output voltage, so it is difficult to design and generates a lot of noise. There is an advantage that the efficiency is good in applications where the voltage difference is large.

  Usually, the DC stabilized power supply apparatus is provided with a circuit for realizing many functions such as an overheat protection function, an overcurrent protection function, and a soft start function.

  Here, FIG. 8 shows a configuration example of a conventional dropper type DC stabilized power supply device. The conventional dropper type DC stabilized power supply device 100 includes an output transistor 3, a control circuit 4, a soft start circuit 8, an overheat protection circuit 9, an overcurrent protection circuit 10, a NOR circuit 11, a transistor 12, The constant voltage circuit 13 includes an input terminal IN, an output terminal OUT, a feedback terminal FB, and a ground terminal GND. The control circuit 4 includes a drive transistor 5, an error amplifier 6, and a reference voltage source 7.

The ground terminal GND of the conventional dropper type DC stabilized power supply apparatus 100 is grounded. An input power supply unit including a DC voltage source 1 and a capacitor 2 applies an input voltage V _IN to an input terminal IN of a conventional dropper type DC stabilized power supply device 100. The output transistor 3 drops the input voltage V _IN applied to the input terminal IN by an emitter-collector voltage, converts it to the output voltage V _OUT and outputs it to the output terminal OUT. The constant voltage circuit 13 converts the input voltage V _IN applied to the input terminal IN into a voltage having a predetermined value, the error amplifier 6, the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and A drive voltage is supplied to each OR circuit 11.

A voltage dividing circuit including resistors 14 and 15, an output capacitor 16, and a load 17 are connected to the output terminal OUT of the conventional dropper type DC stabilized power supply device 100. The voltage dividing circuit including the resistors 14 and 15 supplies the divided voltage V _D of the output voltage V _OUT to the feedback terminal FB of the conventional dropper type DC stabilized power supply apparatus 100.

The error amplifier 6 supplies an error signal obtained by amplifying an error between the divided voltage V _D of the output voltage V _OUT and the reference voltage output from the reference voltage source 7 to the base of the drive transistor 5. Further, since the collector of the driving transistor 5 and the base of the output transistor 3 are connected, the collector current of the driving transistor 5 becomes the base current of the output transistor 3. Therefore, the control circuit 4 including the drive transistor 5, the error amplifier 6, and the reference voltage source 7 outputs so that the divided voltage V _D of the output voltage V _OUT matches the reference voltage output from the reference voltage source 7. The transistor 3 is controlled. As a result, the output voltage V _OUT is stabilized at a predetermined value.

  The overheat protection circuit 9 determines whether or not the junction temperature of the direct current stabilizing device is equal to or higher than a predetermined value. If the junction temperature is equal to or higher than the predetermined value, the overheat protection circuit 9 outputs a High level signal to the OR circuit 11. If the temperature is not equal to or higher than the predetermined value, a low level signal is output to the OR circuit 11. The overcurrent protection circuit 10 determines whether or not the current flowing from the input terminal IN to the output terminal OUT via the output transistor 3 is equal to or greater than a predetermined value. A level signal is output to the OR circuit 11, and if the current is not greater than a predetermined value, a low level signal is output to the OR circuit 11. If at least one of the output of the overheat protection circuit 9 and the output of the overcurrent protection circuit 10 is at a high level, the output of the OR circuit 11 is at a high level and the transistor 12 is turned on. Regardless of the output, the base voltage of the driving transistor 5 becomes low level, and the driving transistor 5 and the output transistor 3 are turned off. As a result, it is possible to prevent an increase in internal heat generation due to a heavy load or an abnormal increase in the ambient temperature, so that the junction temperature of the DC stabilized power supply device does not exceed a predetermined value, and the output transistor from the input terminal IN. It is possible to prevent the current flowing toward the output terminal OUT through 3 from exceeding a predetermined value.

The soft start circuit 8 is a circuit for gradually increasing the output voltage V _OUT by gradually increasing the base voltage of the drive transistor 5 regardless of the output of the error amplifier 6 at the start of the control operation of the control circuit 4. In other words, it is a circuit for performing a so-called soft start operation.

  In the conventional dropper type DC stabilized power supply apparatus 100 shown in FIG. 8, even when the load is in a standby state and the current consumption of the load is extremely small compared to the normal time, the current consumed by the DC stabilized power supply itself is sufficient. It was difficult to reduce the power consumption of the entire device having a DC stabilized power supply.

As a solution to this problem, in Patent Document 1, when the load is in a standby state with less power consumption than usual, power supply to the control circuit that controls the power control element that controls the power supplied to the load is stopped. There has been proposed a stabilized DC power supply that turns off the power control element.
JP 2000-209776 A

  However, in the stabilized DC power supply device proposed in Patent Document 1, when the load is in the standby state, the power control element is turned off, so that the output voltage of the stabilized DC power supply device is kept stable. Therefore, it is necessary to use a large-capacity capacitor as the output capacitor connected to the output terminal of the DC stabilized power supply device together with the load. Therefore, the stabilized DC power supply proposed in Patent Document 1 cannot use a small-capacity output transistor, and it is difficult to reduce the size of the entire electrical apparatus having the stabilized DC power supply.

  In view of the above problems, an object of the present invention is to provide a stabilized DC power supply device that can reduce power consumption and that can use a small-capacity output capacitor.

  In order to achieve the above object, a stabilized DC power supply according to the present invention includes a voltage control element that controls a voltage supplied to a load, and a control that controls the voltage control element so that an output voltage to the load is stabilized. Circuit, an additional unit that has at least one of an overcurrent protection circuit, an overheat protection circuit, and a soft start circuit and controls the voltage control element regardless of the output of the control circuit, and the load consumes more power than usual. A load state detection unit that determines whether or not the load is in a standby state, and outputs the determination result to the additional unit when the load is in a standby state according to the output of the load state detection unit Power supply control means for stopping power supply and supplying power to the additional unit when the load is not in a standby state.

  With the above configuration, when the load is in a standby state, power supply to the additional unit is stopped, and this state is maintained until the load is in an operating state. Thereby, the power consumption of the DC stabilized power supply device when the load is in a standby state can be reduced. Further, since the output current is supplied from the stabilized DC power supply device to the load even when the load is in the standby state, the output capacitor connected to the stabilized DC power supply device together with the load has a small capacitance. Can be used.

  As an embodiment of the load state detection means, a signal based on the current flowing through the load is input, and it is determined whether or not the load is in a standby state with less power consumption than normal based on the input signal. A load state detecting means for performing the operation. Further, when the load is a load that outputs a load state signal indicating its own state, the load state signal is input as the load state detection unit, and the load is detected based on the input load state signal. It is possible to use a load state detection unit that determines whether or not the standby state has less power consumption than usual.

  In addition, drive current detection means for detecting a drive current flowing to the control terminal of the voltage control element is provided, and the load state detection means consumes less power than usual based on the output of the drive current detection means. You may make it determine whether it is a standby state. This eliminates the need for the load state detection means to input a signal from the outside.

  In addition, a current detection unit that detects an input current or an output current of the voltage control element is provided, and the load state detection unit is in a standby state in which the load is less in power consumption than normal based on the output of the current detection unit. It may be determined whether or not there is. This eliminates the need for the load state detection means to input a signal from the outside. Further, the additional unit includes at least the overcurrent protection circuit, and the overcurrent protection circuit includes a current detection unit that detects an input current or an output current of the voltage control element, and the current detection unit and the current detection unit The part may be shared. Thereby, the circuit can be simplified.

  Further, a signal based on the output of the load state detecting means may be output to the outside. Thus, by using a signal based on the output of the load state detecting means, it is possible to easily recognize the load state even outside the stabilized DC power supply device. For example, if the load inputs a signal based on the output of the load state detecting means, the load can easily recognize its own state.

  Further, in any one of the above-described DC stabilized power supply apparatuses, when the load is in a standby state, power supply to the additional unit is stopped and the load is in a standby state according to the output of the load state detection unit. In place of the power supply control means for supplying power to the additional section when not in a state, the power supply to the additional section and the additional power are applied when the load is in a standby state according to the output of the load state detecting means. Stopping power supply to the unit is repeated at a predetermined time ratio, and a standby state intermittent power supply type power supply control means for supplying power to the additional unit when the load is not in the standby state may be provided. .

  Thereby, even when the load is in the standby state, the additional unit operates intermittently, so that it is possible to cope with overheating, overcurrent, etc. that do not normally occur when the load is in the standby state, Reliability is improved.

  Moreover, the electric equipment according to the present invention includes the above-described stabilized DC power supply device according to the present invention. Since the stabilized DC power supply apparatus according to the present invention can reduce power consumption and use a small-capacity output capacitor, it is possible to reduce the power consumption and size of the electrical apparatus according to the present invention. Can do.

  According to the present invention, it is possible to realize a stabilized DC power supply apparatus that can reduce power consumption and that can use a small-capacity output capacitor.

  An embodiment of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 shows the configuration of the stabilized DC power supply device according to the first embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  A stabilized DC power supply apparatus 101 (hereinafter referred to as a stabilized DC power supply apparatus 101) according to the first embodiment of the present invention includes a load state detection circuit 18, a power cutoff circuit, and the conventional stabilized DC power supply apparatus 100 shown in FIG. 19 and a terminal T1 are newly provided. A load current detection circuit 20 that detects a current flowing through the load 17 is provided between the output terminal OUT of the DC stabilized power supply apparatus 101 and the load 17. The load current detection circuit 20 supplies a voltage corresponding to the current flowing through the load 17 to the terminal T1 of the DC stabilized power supply device 101. In the present embodiment, the load current detection circuit 20 includes a current detection resistor (not shown) provided between the output terminal OUT of the DC stabilized power supply device 101 and the load 17 and a voltage across the current detection resistor. It is assumed that the circuit comprises a comparator (not shown) to be compared, and the load current detection circuit 20 supplies a voltage proportional to the current flowing through the load 17 to the terminal T1 of the DC stabilized power supply device 101.

The constant voltage circuit 13 converts the input voltage V _IN applied to the input terminal IN into a voltage having a predetermined value, and supplies the voltage to the error amplifier 6, the load state detection circuit 18, and the power cutoff circuit 19 as drive voltages.

  The load state detection circuit 18 determines whether or not the load 17 is in a standby state based on the voltage applied to the terminal T1. In this embodiment, if the voltage applied to the terminal T1 is equal to or higher than a predetermined threshold, the load state detection circuit 18 determines that the load 17 is not in a standby state, and supplies a power supply signal (for example, a high level signal) to the power cut-off circuit 19. If the voltage applied to the terminal T1 is not equal to or greater than a predetermined threshold value, the load state detection circuit 18 determines that the load 17 is in a standby state, and supplies a power cut signal (for example, a power cut signal) Low level voltage signal). One embodiment of the load state detection circuit 18 includes, for example, a constant voltage source that outputs a voltage having a predetermined threshold value, and a comparator that compares the voltage applied to the terminal T1 with the output voltage of the constant voltage source. The circuit which consists of.

  The power cut-off circuit 19 turns on / off power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 in accordance with a signal from the load state detection circuit 18. In this embodiment, when the power cutoff circuit 19 receives a power supply signal from the load state detection circuit 18, the output voltage of the constant voltage circuit 13 is changed to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR. When each circuit 11 is supplied as a drive voltage and a power cut-off signal is input from the load state detection circuit 18, the output voltage of the constant voltage circuit 13 is supplied to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit. 11 is not supplied. That is, the power shutoff circuit 19 includes a soft start circuit 8, an overheat protection circuit 9, an overcurrent protection circuit 10, and an OR circuit 11 when the load 17 is in a standby state according to the output of the load state detection circuit 18. It functions as a power supply control unit that stops power supply to the additional unit and supplies power to the additional unit when the load 17 is not in a standby state. As one embodiment of the power shutoff circuit 19, for example, there is a switch that is turned on when a high level voltage signal is inputted to the control terminal and turned off when a low level voltage signal is inputted to the control terminal. Can be mentioned.

With the above configuration, when the load 17 is in the standby state, the power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 is cut off by the power cut-off circuit 19, and the load 17 operates. This state is maintained until the state is reached. Thereby, the power consumption of the direct current | flow stabilized power supply device 101 when the load 17 is a standby state can be reduced. When the load 17 is in the standby state, the current consumption of the load 17 is very small, so that no overcurrent flows through the DC stabilized power supply device 101 and the heat generation is small, so that the load 17 is in the standby state. Even if the current protection circuit 10 and the overheat protection circuit 9 are not operating, there is no problem. The soft start circuit 8 needs to be operated in order to slowly increase the output voltage V _OUT at the start of the control operation of the control circuit 4. However, once the output voltage V _OUT rises, the soft start circuit 8 operates. Therefore, there is no problem even if the soft start circuit 8 is not operating when the load 17 is in the standby state.

  Further, with the above configuration, since the output current is supplied from the DC stabilized power supply apparatus 101 to the load 17 even when the load 17 is in a standby state, a small-capacitance capacitor can be used as the output capacitor 16. As a result, it is possible to reduce the size of the electrical apparatus having the DC stabilized power supply device 101. Therefore, the stabilized DC power supply device 101 is suitable as a power supply device for portable devices such as mobile phones, PDAs, and portable audio devices that require low power consumption and miniaturization.

  Next, a second embodiment of the present invention will be described. FIG. 2 shows the configuration of the stabilized DC power supply device according to the second embodiment of the present invention. 2, the same parts as those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The stabilized DC power supply 102 (hereinafter referred to as the stabilized DC power supply 102) according to the second embodiment of the present invention includes a power cutoff circuit 19 and a load state detection circuit in addition to the conventional stabilized DC power supply 100 shown in FIG. 21 and a terminal T2 are newly provided. Further, instead of the load 17, a load 17 ′ is connected to the output terminal OUT of the DC stabilized power supply device 102. The load 17 ′ supplies a load state signal to the terminal T <b> 2 of the DC stabilized power supply apparatus 102.

The constant voltage circuit 13 converts the input voltage V _IN applied to the input terminal IN into a voltage having a predetermined value, and supplies the voltage to the error amplifier 6, the load state detection circuit 21, and the power cutoff circuit 19 as drive voltages.

  The load state detection circuit 21 determines whether or not the load 17 'is in a standby state based on the load state signal input to the terminal T2. In the present embodiment, when the load state detection circuit 21 determines that the load 17 ′ is not in the standby state, the load state detection circuit 21 supplies a power supply signal (for example, a high level voltage signal) to the power cutoff circuit 19 and the load 17 is in the standby state. If it is determined that there is, a power cutoff signal (for example, a low level voltage signal) is supplied to the power cutoff circuit 19.

  The power cut-off circuit 19 turns on / off power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 in accordance with a signal from the load state detection circuit 21. In this embodiment, when the power cut-off circuit 19 receives a power supply signal from the load state detection circuit 21, the output voltage of the constant voltage circuit 13 is changed to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR. When each circuit 11 is supplied as a drive voltage and a power cut-off signal is input from the load state detection circuit 21, the output voltage of the constant voltage circuit 13 is supplied to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit. 11 is not supplied. As one embodiment of the power shutoff circuit 19, for example, there is a switch that is turned on when a high level voltage signal is inputted to the control terminal and turned off when a low level voltage signal is inputted to the control terminal. Can be mentioned.

With the above configuration, when the load 17 ′ is in the standby state, the power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 is cut off by the power cut-off circuit 19, and the load 17 ′. This state is maintained until the operation state becomes active. Thereby, the power consumption of the direct current | flow stabilized power supply device 102 when load 17 'is a standby state can be reduced. Note that when the load 17 ′ is in the standby state, the current consumption of the load 17 ′ is very small. Therefore, no overcurrent flows through the DC stabilized power supply 102, and heat generation is also small, so that the load 17 ′ is in the standby state. In this case, there is no problem even if the current protection circuit 10 and the overheat protection circuit 9 are not operating. The soft start circuit 8 needs to be operated in order to slowly increase the output voltage V _OUT at the start of the control operation of the control circuit 4. However, once the output voltage V _OUT rises, the soft start circuit 8 operates. Therefore, there is no problem even if the soft start circuit 8 is not operating when the load 17 'is in a standby state.

  Further, with the above configuration, since the output current is supplied from the DC stabilized power supply 102 to the load 17 ′ even when the load 17 ′ is in a standby state, a small-capacitance capacitor can be used as the output capacitor 16. As a result, it is possible to reduce the size of the electrical apparatus having the DC stabilized power supply device 102. Therefore, the stabilized DC power supply 102 is suitable as a power supply for portable devices such as mobile phones, PDAs, and portable audio devices that require low power consumption and miniaturization.

  In the configuration of FIG. 2, a similar effect can be obtained by providing a load that switches between a standby state and an operating state by an external control signal instead of the load 17 ′, and supplying the external control signal to the terminal T2. Can be obtained.

  Next, a third embodiment of the present invention will be described. FIG. 3 shows the configuration of the stabilized DC power supply device according to the third embodiment of the present invention. 3, the same parts as those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  A stabilized DC power supply device 103 (hereinafter referred to as a stabilized DC power supply device 103) according to a third embodiment of the present invention includes a power cutoff circuit 19 and a drive current detection circuit in addition to the conventional stabilized DC power supply device 100 shown in FIG. 22 and a load state detection circuit 23 are newly provided.

The constant voltage circuit 13 converts the input voltage V _IN applied to the input terminal IN into a voltage having a predetermined value, and supplies the converted voltage to the error amplifier 6, the power cut-off circuit 19, and the load state detection circuit 23 as drive voltages.

  The drive current detection circuit 22 supplies a voltage corresponding to the emitter current of the drive transistor 5 to the load state detection circuit 23. In the present embodiment, the drive current detection circuit 22 includes a current detection resistor (not shown) provided between the drive transistor 5 and the ground terminal GND and a comparator (not shown) that compares the voltage across the current detection resistor. It is assumed that the drive current detection circuit 22 supplies a voltage proportional to the emitter current of the drive transistor 5 to the load state detection circuit 23.

  The load state detection circuit 23 determines whether or not the load 17 is in a standby state based on the voltage supplied from the drive current detection circuit 22. In this embodiment, if the voltage supplied from the drive current detection circuit 22 is equal to or higher than a predetermined threshold, the load state detection circuit 23 determines that the load 17 is not in a standby state, and supplies a power supply signal (for example, a power supply signal) If the voltage supplied from the drive current detection circuit 22 is not equal to or higher than a predetermined threshold value, the load state detection circuit 23 determines that the load 17 is in the standby state, and the power cut-off circuit 19 Is supplied with a power cutoff signal (eg, a low level voltage signal). As one embodiment of the load state detection circuit 23, for example, a constant voltage source that outputs a voltage of a predetermined threshold value, a comparison that compares the voltage supplied from the drive current detection circuit 22 and the output voltage of the constant voltage source The circuit which consists of a container is mentioned.

  The power cut-off circuit 19 turns on / off power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 in accordance with a signal from the load state detection circuit 23. In this embodiment, when the power cut-off circuit 19 receives a power supply signal from the load state detection circuit 23, the output voltage of the constant voltage circuit 13 is changed to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR. When each circuit 11 is supplied as a drive voltage and a power cut-off signal is input from the load state detection circuit 23, the output voltage of the constant voltage circuit 13 is supplied to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit. 11 is not supplied. As one embodiment of the power shutoff circuit 19, for example, there is a switch that is turned on when a high level voltage signal is inputted to the control terminal and turned off when a low level voltage signal is inputted to the control terminal. Can be mentioned.

With the above configuration, when the load 17 is in the standby state, the power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 is cut off by the power cut-off circuit 19, and the load 17 operates. This state is maintained until the state is reached. Thereby, the power consumption of the direct current | flow stabilized power supply device 103 when the load 17 is a standby state can be reduced. Note that when the load 17 is in the standby state, the current consumption of the load 17 is very small, so that no overcurrent flows through the DC stabilized power supply device 103, and there is little heat generation, so the load 17 is in the standby state. Even if the current protection circuit 10 and the overheat protection circuit 9 are not operating, there is no problem. The soft start circuit 8 needs to be operated in order to slowly increase the output voltage V _OUT at the start of the control operation of the control circuit 4. However, once the output voltage V _OUT rises, the soft start circuit 8 operates. Therefore, there is no problem even if the soft start circuit 8 is not operating when the load 17 is in the standby state.

  In addition, with the above configuration, since the output current is supplied from the DC stabilized power supply apparatus 103 to the load 17 even when the load 17 is in a standby state, a small-capacitance capacitor can be used as the output capacitor 16. As a result, it is possible to reduce the size of the electric apparatus having the DC stabilized power supply device 103. Therefore, the stabilized DC power supply device 103 is suitable as a power supply device for portable equipment such as a mobile phone, a PDA, and a portable audio equipment that require low power consumption and miniaturization.

  Next, a fourth embodiment of the present invention will be described. FIG. 4 shows the configuration of the stabilized DC power supply device according to the fourth embodiment of the present invention. 4 that are the same as those in FIG. 8 are given the same reference numerals, and detailed descriptions thereof are omitted.

  A stabilized DC power supply device 104 (hereinafter referred to as a stabilized DC power supply device 104) according to a fourth embodiment of the present invention includes a power cutoff circuit 19 and a current detection circuit 24 in addition to the conventional stabilized DC power supply device 100 shown in FIG. The load state detection circuit 25 is newly provided.

The constant voltage circuit 13 converts the input voltage V _IN applied to the input terminal IN into a voltage having a predetermined value, and supplies the voltage to the error amplifier 6, the power cut-off circuit 19, and the load state detection circuit 25 as drive voltages.

  The current detection circuit 24 supplies a voltage corresponding to the emitter current of the output transistor 3 to the load state detection circuit 25. In the present embodiment, the current detection circuit 24 includes a current detection resistor (not shown) provided between the input terminal IN and the output transistor 3 and a comparator (not shown) that compares the voltage across the current detection resistor. The current detection circuit 24 supplies a voltage proportional to the emitter current of the output transistor 3 to the load state detection circuit 25.

  The load state detection circuit 25 determines whether or not the load 17 is in a standby state based on the voltage supplied from the current detection circuit 24. In the present embodiment, if the voltage supplied from the current detection circuit 24 is equal to or higher than a predetermined threshold, the load state detection circuit 25 determines that the load 17 is not in a standby state, and sends a power supply signal (for example, High) to the power cut-off circuit 19. If the voltage supplied from the current detection circuit 24 is not equal to or higher than a predetermined threshold value, the load state detection circuit 25 determines that the load 17 is in a standby state, and supplies power to the power cut-off circuit 19. A cutoff signal (for example, a low level voltage signal) is supplied. As one embodiment of the load state detection circuit 25, for example, a constant voltage source that outputs a voltage of a predetermined threshold, and a comparator that compares the voltage supplied from the current detection circuit 24 with the output voltage of the constant voltage source. A circuit consisting of

  The power cutoff circuit 19 turns on / off the power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 in accordance with a signal from the load state detection circuit 25. In this embodiment, when the power cut-off circuit 19 receives a power supply signal from the load state detection circuit 25, the output voltage of the constant voltage circuit 13 is changed to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR. When each circuit 11 is supplied as a drive voltage and a power cut-off signal is input from the load state detection circuit 25, the output voltage of the constant voltage circuit 13 is supplied to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit. 11 is not supplied. As one embodiment of the power shutoff circuit 19, for example, there is a switch that is turned on when a high level voltage signal is inputted to the control terminal and turned off when a low level voltage signal is inputted to the control terminal. Can be mentioned.

With the above configuration, when the load 17 is in the standby state, the power supply to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 is cut off by the power cut-off circuit 19, and the load 17 operates. This state is maintained until the state is reached. Thereby, the power consumption of the direct current | flow stabilized power supply device 104 when the load 17 is a standby state can be reduced. Note that when the load 17 is in the standby state, the current consumption of the load 17 is very small, so that no overcurrent flows through the DC stabilized power supply device 104, and there is little heat generation, so the load 17 is in the standby state. Even if the current protection circuit 10 and the overheat protection circuit 9 are not operating, there is no problem. Further, the soft start circuit 8 needs to operate in order to slowly increase the output voltage V _OUT when the control circuit 4 starts the control operation. However, once the output voltage V _OUT rises, the soft start circuit 8 operates. Therefore, there is no problem even if the soft start circuit 8 is not operating when the load 17 is in the standby state.

  Further, with the above configuration, since the output current is supplied from the DC stabilized power supply device 104 to the load 17 even when the load 17 is in a standby state, a small-capacitance capacitor can be used as the output capacitor 16. As a result, it is possible to reduce the size of the electrical device having the DC stabilized power supply device 104. Accordingly, the stabilized DC power supply device 104 is suitable as a power supply device for portable equipment such as a mobile phone, a PDA, and a portable audio device that require low power consumption and downsizing.

  The overcurrent protection circuit 10 connects the output transistor 3 from the input terminal IN to determine whether or not the current flowing from the input terminal IN to the output terminal OUT via the output transistor 3 is equal to or greater than a predetermined value. Since the current detection circuit for detecting the current flowing toward the output terminal OUT is provided, the current detection circuit of the overcurrent protection circuit 10 and the current detection circuit 24 described above are shared, thereby simplifying the circuit. Can be achieved. Further, the current detection circuit 24 may be provided between the output transistor 3 and the output terminal OUT without being provided between the input terminal IN and the output transistor 3.

  Next, a fifth embodiment of the present invention will be described. FIG. 5 shows the configuration of a stabilized DC power supply device according to the fifth embodiment of the present invention. 5 that are the same as those in FIG. 1 are assigned the same reference numerals, and detailed descriptions thereof are omitted.

  A stabilized DC power supply device 105 (hereinafter referred to as a stabilized DC power supply device 105) according to a fifth embodiment of the present invention outputs a signal corresponding to a load state to the stabilized DC power supply device 101 shown in FIG. A terminal T3 is newly provided. The terminal T3 is a terminal that outputs a signal output from the load state detection circuit 18 to the outside. The stabilized DC power supply device 105 can achieve the same effect as the stabilized DC power supply device 101, and can easily load a load state outside the stabilized DC power supply device 105 by using a signal output from the terminal T3. Can be recognized. For example, if the load 17 inputs a signal output from the terminal T3, the load 17 can easily recognize its own state.

  In addition, although this embodiment demonstrated the structure which provided the terminal T3 which outputs the signal according to a load state outside in the direct current | flow stabilized power supply device 101 shown in FIG. Similarly, the same effect can be obtained by providing a terminal for outputting a signal corresponding to the load state to the outside.

  Next, a sixth embodiment of the present invention will be described. FIG. 6 shows the configuration of the stabilized DC power supply device according to the sixth embodiment of the present invention. In FIG. 6, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The stabilized DC power supply device 106 (hereinafter referred to as the stabilized DC power supply device 106) according to the sixth embodiment of the present invention has a configuration in which a timer circuit 26 is newly provided in the stabilized DC power supply device 101 shown in FIG. . Here, FIG. 7 shows a time chart of signals and states of the respective parts of the DC stabilized power supply device 106. 7, S1 indicates a voltage signal (power supply signal and power cutoff signal) output from the load state detection circuit 18, S2 indicates a voltage signal output from the timer circuit 26, and S3 indicates from the power cutoff circuit 19. The power supply states to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 are shown.

  The timer circuit 26 controls the power cutoff circuit 19 in accordance with the signal output from the load state detection circuit 18. When it is determined by the load state detection circuit 18 that the load 17 is not in the standby state and a power cut-off signal (low level voltage signal in this embodiment) is output from the load state detection circuit 18, that is, the voltage signal S1 is at the low level. In some cases, the timer circuit 26 outputs a pulse signal in which the High level and the Low level are repeated with a predetermined duty ratio (see the voltage signal S2 in FIG. 7), and the power shut-off circuit 19 is intermittently generated according to the pulse signal. Power is supplied to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR circuit 11 (see the power supply state S3 in FIG. 7). On the other hand, when the load state detection circuit 18 determines that the load 17 is not in the standby state and the load state detection circuit 18 outputs a power supply signal (a high-level voltage signal in this embodiment), that is, the voltage signal S1 is high. In the case of the level, the timer circuit 26 outputs a high level signal (refer to the voltage signal S2 in FIG. 7), and the power shut-off circuit 19 continuously applies the soft start circuit 8 and the overheat protection according to the high level signal. Power is supplied to the circuit 9, the overcurrent protection circuit 10, and the OR circuit 11. That is, the timer circuit 26 and the power cut-off circuit 19 are connected to the soft start circuit 8, the overheat protection circuit 9, the overcurrent protection circuit 10, and the OR when the load 17 is in a standby state according to the output of the load state detection circuit 18. As power supply control means for repeatedly supplying power to the additional unit comprising the circuit 11 and stopping the power supply to the additional unit at a predetermined time ratio and supplying power to the additional unit when the load 17 is not in a standby state. It is functioning.

  The DC stabilized power supply device 106 is effective in the same manner as the DC stabilized power supply device 101, and even when the load 17 is in the standby state as described above, the soft start circuit 8, the overheat protection circuit 9, Since the current protection circuit 10 and the OR circuit 11 operate, it is possible to cope with overheating, overcurrent, etc. that do not normally occur when the load 17 is in a standby state, and safety and reliability are improved.

  In the present embodiment, the configuration in which the timer circuit 26 is newly provided in the DC stabilized power supply apparatus 101 illustrated in FIG. 1 has been described. However, the DC stabilized power supply apparatuses 102 to 105 are similarly provided with a timer circuit. Similar effects can be obtained.

  In the first to sixth embodiments described above, the dropper type stabilized DC power supply device has been described. However, the present invention can also be applied to a switched DC stabilized power supply device.

These are figures which show the structure of the direct current | flow stabilizer which concerns on 1st embodiment of this invention. These are figures which show the structure of the direct current | flow stabilizer which concerns on 2nd embodiment of this invention. These are figures which show the structure of the direct current | flow stabilizer which concerns on 3rd embodiment of this invention. These are figures which show the structure of the direct current | flow stabilizer which concerns on 4th embodiment of this invention. These are figures which show the structure of the direct current | flow stabilizer which concerns on 5th embodiment of this invention. These are figures which show the structure of the direct current | flow stabilizer which concerns on 6th embodiment of this invention. These are the time charts which show the signal and state of each part of the direct-current stabilization apparatus shown in FIG. These are figures which show the example of 1 structure of the conventional dropper type direct current | flow stabilized power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC voltage source 2 Capacitor 3 Output transistor 4 Control circuit 5 Drive transistor 6 Error amplifier 7 Reference voltage source 8 Soft start circuit 9 Overheat protection circuit 10 Overcurrent protection circuit 11 OR circuit 12 Transistor 13 Constant voltage circuit 14, 15 Resistance 16 Output transistor 17 Load 18, 21, 23, 25 Load state detection circuit 19 Power cut-off circuit 20 Load current detection circuit 22 Drive current detection circuit 24 Current detection terminal 26 Timer circuit IN input terminal FB feedback terminal OUT output terminal T1 to T3 terminal

Claims (9)

At least one of a voltage control element that controls a voltage supplied to the load, a control circuit that controls the voltage control element so that an output voltage to the load is stabilized, an overcurrent protection circuit, an overheat protection circuit, and a soft start circuit In a DC stabilized power supply device including an additional unit that controls the voltage control element regardless of the output of the control circuit having one,
It is determined whether or not the load is in a standby state with less power consumption than normal, and a load state detection unit that outputs the determination result;
Power supply control for stopping power supply to the additional unit when the load is in a standby state and supplying power to the additional unit when the load is not in a standby state according to the output of the load state detection means Means,
A stabilized DC power supply apparatus comprising:   The load state detection means receives a signal based on the current flowing through the load, and determines whether the load is in a standby state with less power consumption than normal based on the input signal. The stabilized DC power supply device described. The load outputs a load state signal indicating its own state,
2. The load state detection unit according to claim 1, wherein the load state detection unit inputs the load state signal and determines whether or not the load is in a standby state with less power consumption than normal based on the input load state signal. DC stabilized power supply. Drive current detection means for detecting a drive current flowing to the control terminal of the voltage control element,
2. The stabilized DC power supply device according to claim 1, wherein the load state detection unit determines whether or not the load is in a standby state with less power consumption than normal based on an output of the drive current detection unit. Current detection means for detecting an input current or an output current of the voltage control element;
2. The stabilized DC power supply device according to claim 1, wherein the load state detection unit determines whether or not the load is in a standby state with less power consumption than normal based on an output of the current detection unit. The additional unit has at least the overcurrent protection circuit;
The overcurrent protection circuit has a current detection unit for detecting an input current or an output current of the voltage control element;
6. The stabilized DC power supply device according to claim 5, wherein the current detection unit and the current detection unit are shared.   The stabilized DC power supply device according to any one of claims 1 to 6, wherein a signal based on an output of the load state detection means is output to the outside. In the direct-current stabilized power supply device in any one of Claims 1-7,
Power supply control for stopping power supply to the additional unit when the load is in a standby state and supplying power to the additional unit when the load is not in a standby state according to the output of the load state detection means Instead of means,
Depending on the output of the load state detection means, when the load is in a standby state, the supply of power to the additional unit and the stop of the supply of power to the additional unit are repeated at a predetermined time ratio, and the load is in a standby state. A stabilized direct-current power supply apparatus comprising a standby state intermittent power supply type power supply control means for supplying power to the additional unit when not in a state.   An electrical apparatus comprising the stabilized DC power supply device according to claim 1.

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