JP2008125349A - Power supply device and power supply feeding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To utilize a power supply having only a small current supplying capability than a maximum current used in an apparatus, and a semiconductor chip having only a small current allowable value than a maximum current used in the apparatus; and to obtain a power supply device and a method capable of continuing the operation of an apparatus, even if the current reaches such an allowable value. <P>SOLUTION: Groups of currents IL1 to ILm outputted from DC constant-voltage circuits CV1 to CVm to corresponding loads LD1 to LDm are detected by load-current detecting circuits DT1 to DTm, respectively. A load-current control circuit 3 reduces current consumption sequentially from a low priority order in the loads LD1 to LDm, when the total of the detected current values exceeds a predetermined level. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply device and a power supply method applied to a device that uses a large number of power supply circuits such as a mobile phone and a digital camera, and more particularly to a device whose current consumption varies greatly depending on the state of use. The present invention relates to a power supply device and a power supply method.

  In recent years, the integration of semiconductors has progressed and the functions of devices have increased, and the demand for power saving in consideration of the environment has further increased. From such a background, by arranging an optimal power source for each of a large number of functions included in a device, desired performance of each function has been obtained and power saving has been achieved. Thus, it is considered that the incorporation of a plurality of DC constant voltage circuits corresponding to each function of the device into one device will further increase in the future.

  A DC constant voltage circuit that is generally used at present is often provided with a protection circuit in order to protect the power supply circuit and the load circuit itself from an excessive load current. When many DC constant voltage circuits are provided, it is of course necessary to provide overcurrent protection for each DC constant voltage circuit, but the current consumption in each DC constant voltage circuit is less than the current at which the protection circuit operates. Even in such a case, the current consumption of the entire power supply circuit may exceed the power supply capacity of the DC power supply that supplies power to each DC constant voltage circuit or the allowable current value of the semiconductor chip in which each DC constant voltage circuit is integrated. There was.

  Such a problem can be avoided by setting the power supply capacity of the DC power supply to the sum of the protection currents of the DC constant voltage circuits. However, if this is done, the current capacity of the DC power supply may become too large, and a current capacity that is greater than the maximum current used in the equipment may be required, so as to ensure an extra power capacity that is not used. There was a problem that waste of space and cost would occur. On the other hand, both the space and the cost can be improved by setting the power supply capacity of the DC power supply to the maximum current when the device is used.

For this reason, an overcurrent protection circuit is provided for each DC constant voltage circuit, the current capacity of the DC power supply is set to the maximum current that can be used by the device, and the current value output from the DC power supply is detected before the DC constant voltage circuit. Then, when the detected current value exceeds the maximum current, a device that stops the operation of the device has been proposed. An example of such a power supply device is shown in FIG.
In FIG. 5, the power supply apparatus 100 includes m (m is an integer of m> 1) DC constant voltage circuits P1 to Pm, and each DC constant voltage circuit P1 to Pm includes an overcurrent protection circuit. Is provided.

  Power input to the power input terminal IN is supplied to each input terminal of the DC constant voltage circuits P1 to Pm via a P-channel MOS transistor (hereinafter referred to as a PMOS transistor) Ma and a resistor Ra. That is, the sum of the consumption currents of the DC constant voltage circuits P1 to Pm flows through the resistor Ra. In the initial state, while the current flowing through the resistor Ra is small, the resistors Rb to Rf are set so that the voltage V1 input to the non-inverting input terminal of the comparator 101 is smaller than the voltage V2 input to the inverting input terminal. Has been.

  When the output terminal of the comparator 101 is at a low level, the PMOS transistor Ma is turned on, and power is supplied to each of the DC constant voltage circuits P1 to Pm via the resistor Ra. When a current flows through the resistor Ra, the input voltage V2 of the comparator 101 gradually decreases. When the input voltage V1 becomes smaller than the input voltage V1, the output terminal of the comparator 101 becomes a high level, and the PMOS transistor Ma is turned off to be cut off. become.

  At this time, the feedback resistor Rb connected from the output terminal of the comparator 101 to the non-inverting input terminal causes the input voltage V1 to be larger than the input voltage V2, and the PMOS transistor Ma maintains the OFF state. Current supply to P1 to Pm is cut off. Such a state continues until the power is turned on again or reset by a reset circuit (not shown) or the like. In this way, a DC power source (not shown) that supplies power to the power input terminal IN, a semiconductor chip that forms the power supply device, and a load connected to the DC constant voltage circuits P1 to Pm are prevented from being damaged. be able to.

Although different from the present invention, in the overcurrent protection circuit of the multi-output switching power supply, only the output current of each circuit of the multi-output is detected, and the overcurrent droop of each output and those overcurrent droop are performed. There was a switching power supply (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 6-17389

  However, in such a power supply device 100, when an overcurrent flows, the PMOS transistor Ma is cut off, so that the power supply to each load connected to the DC constant voltage circuits P1 to Pm is stopped. There was a problem that the equipment that made the load could not be used. In addition, there are few cases where the device is used at the maximum current, and since the device normally consumes much less current than the maximum current, wasted space is used to ensure the amount of power that is rarely used. And it was costly.

  The present invention has been made to solve such a problem, and has a power supply having a current supply capability smaller than the maximum current used in the device and a current allowance smaller than the maximum current used in the device. It is an object to provide a power supply device and a power supply method capable of using a semiconductor chip having a capacity and capable of continuing the operation of the device even when the current used in the device reaches such a current allowable amount. To do.

A power supply apparatus according to the present invention includes a plurality of DC constant voltage circuits that generate a predetermined constant voltage from a power supply voltage from a DC power supply and output the same to a corresponding load, and supply power to a plurality of loads In the device
A load current detection circuit unit that detects each current output from each DC constant voltage circuit to a corresponding load, and generates and outputs a signal indicating each detected current value;
The sum of the output currents of the DC constant voltage circuits is calculated from the current values indicated by the output signals from the load current detection circuit unit. When the calculated current sum exceeds a predetermined value, A load current control circuit unit for controlling the operation of each DC constant voltage circuit and each load so that the sum of output currents of the constant voltage circuit is less than or equal to the predetermined value;
Is provided.

  Specifically, the load current control circuit unit applies the load current control circuit unit to each load so that when the calculated total current exceeds a predetermined value, the total output current of each DC constant voltage circuit is equal to or less than the predetermined value. On the other hand, the current consumption is reduced according to a preset order.

  More specifically, the load current control circuit unit, when the total sum of the calculated currents exceeds a predetermined value, determines the current consumption for the load capable of reducing the current consumption according to the state of the load. You may make it reduce.

In these cases, the load current control circuit unit is
A load current processing circuit that converts each current value indicated by each output signal from the load current detection circuit unit into a digital signal and outputs the digital signal;
From each signal output from the load current processing circuit, the sum of output currents of the DC constant voltage circuits is calculated, and when the calculated sum of currents exceeds a predetermined value, the output current of the DC constant voltage circuits A load current control circuit that reduces the current consumption for each of the loads so that the sum of
Consists of
Each of the DC constant voltage circuit, the load current detection circuit unit, and the load current processing circuit is integrated and formed in one IC.

  The DC constant voltage circuit, the load current detection circuit unit, and the load current control circuit unit may be integrated and formed in one IC.

Further, the power supply method according to the present invention detects each current output to each load from a plurality of DC constant voltage circuits that generate a predetermined constant voltage from the power supply voltage from the DC power supply and output it to the corresponding load. A load current detection circuit unit that generates and outputs a signal indicating each detected current value, and each DC constant voltage circuit from each current value indicated by each output signal from the load current detection circuit unit, and In a power supply method of a power supply device comprising a load current control circuit unit for controlling the operation of each load,
Calculate the sum of each current detected by the load current detection circuit unit,
When the calculated sum of currents exceeds a predetermined value, the current consumption is reduced in accordance with a preset order for each load so that the sum of output currents of the DC constant voltage circuits is equal to or less than the predetermined value. Reduced.

  According to the power supply device and the power supply method of the present invention, since the current supply capability of the power supply device can be made smaller than the maximum current consumption required for the equipment constituted by each load, the power supply having a small maximum allowable current The semiconductor chip can be used, and downsizing, cost reduction, and power saving of the device can be achieved. In addition, when the current consumption of the equipment that each load constitutes is close to the maximum current supply capability of the power supply device, it is possible to turn off the power of the conventional equipment simply by controlling the performance of the equipment to be reduced. Thus, it is possible to provide a device that is easy to use without becoming unusable.

Next, the present invention will be described in detail based on the embodiments shown in the drawings.
First embodiment.
FIG. 1 is a block diagram showing an example of a power supply device according to the first embodiment of the present invention.
In FIG. 1, the power supply apparatus 1 outputs m (m is an integer of m> 1) DC constant voltage circuits CV1 to CVm and the DC constant voltage circuits CV1 to CVm to the corresponding loads LD1 to LDm. Further, load current detection circuits DT1 to DTm that detect each current (hereinafter referred to as load current) IL1 to ILm and output the detected load current value are provided.

Further, the power supply device 1 is obtained from the load current processing circuit 2 that stores the load currents IL1 to ILm detected by the load current detection circuits DT1 to DTm by A / D conversion and the load current processing circuit 2. And a load current control circuit 3 that controls the load current consumed by the loads LD1 to LDm in accordance with the load currents IL1 to ILm. The load current detection circuits DT1 to DTm form a load current detection circuit unit, and the load current processing circuit 2 and the load current control circuit 3 form a load current control circuit unit.
The DC constant voltage circuits CV1 to CVm are respectively input with predetermined DC voltages Vi1 to Vim from the DC power supply 10, and the load current detection circuits DT1 to DTm are supplied with the corresponding DC voltages Vi1 to Vim from the DC power supply 10, respectively. Operate. The DC voltages Vi1 to Vim may be different from each other, or may be the same voltage.

  The DC constant voltage circuits CV1 to CVm generate predetermined constant voltages Vo1 to Vom from the voltage input from the DC power supply 10 and output the generated constant voltages Vo1 to Vom to the corresponding loads LD1 to LDm, respectively. To do. At this time, the currents IL1 to ILm output from the DC constant voltage circuits CV1 to CVm to the corresponding loads LD1 to LDm are respectively detected by the corresponding load current detection circuits DT1 to DTm, and the load current detection circuits DT1 to DTm are The signals indicating the detected load currents IL1 to ILm are output to the load current processing circuit 2, respectively.

  The load current processing circuit 2 sequentially converts each current value indicated by each signal input from the load current detection circuits DT1 to DTm into digital data and outputs the digital data to the load current control circuit 3. The load current control circuit 3 calculates the sum of the load currents IL1 to ILm, and compares the calculated sum of the load currents IL1 to ILm with a preset maximum current value. When the sum of the load currents is larger than the maximum current value, the current consumption of the load with the lowest priority among the currently connected loads LD1 to LDm is reduced. As a method for reducing the current consumption, when the operation of the corresponding load may be stopped, the operation of the load is stopped.

  Further, when the operation of the corresponding load cannot be stopped, the load current control circuit 3 reduces the consumption current according to the type of the load. For example, when the load is operating based on the clock signal, the load current control circuit 3 reduces the frequency of the clock signal to reduce the current consumption of the load. For example, when the load is an illumination such as an LED, the load current control circuit 3 reduces the luminance of the illumination to reduce the current consumption. Thus, even if such a consumption current reduction method is performed on the load having the lowest priority, if the sum of the load currents IL1 to ILm is still larger than the maximum current value, the load current control circuit 3 is second. Reduce current consumption for low priority loads. In this way, the load current control circuit 3 reduces the current consumption of the load until the sum of the load currents becomes smaller than the predetermined maximum current value.

  On the other hand, the load current processing circuit 2 includes a multiplexer 11, an A / D converter 12, a control circuit 13 that controls the operation of the multiplexer 11 and the A / D converter 12, and a storage circuit 14. The multiplexer 11 receives signals indicating the detected current values from the load current detection circuits DT1 to DTm, and the multiplexer 11 receives any one of the input signals in response to the control signal MPC from the control circuit 13. Is output to the A / D converter 12. The A / D converter 12 A / D-converts the input signal and outputs it to the control circuit 13. The control circuit 13 stores the digital value input from the A / D converter 13 in the storage circuit 14.

  Similarly, the control circuit 13 sequentially converts each signal indicating the load current detected by the load current detection circuits DT1 to DTm into a digital value, and causes the storage circuit 14 to store the converted digital values. Further, when the control circuit 13 repeatedly performs such an operation, the storage circuit 14 always stores the latest load current values output from the DC constant voltage circuits CV1 to CVm. The load current control circuit 3 calculates the sum of the latest load currents IL1 to ILm stored in the storage circuit 14, and compares the calculated sum of the load currents with a predetermined maximum current value.

  Here, the load current control circuit 3 sequentially changes the priority for supplying power to the loads LD1 to LDm depending on the use modes and use states of the loads LD1 to LDm. Is provided with an information storage circuit (not shown) in which information defining priority is stored. When the sum of the load currents IL1 to ILm is larger than the maximum current value, the load current control circuit 3 reads the use mode and the use state from each of the loads LD1 to LDm, and according to the information stored in the information storage circuit, As described above, the current consumption of the load is reduced.

  In this way, when the sum of the current consumption of each load LD1 to LDm is near the preset maximum current value, the performance of each load LD1 to LDm is somewhat degraded, but the power consumption is reduced and the power is supplied. The space of the apparatus provided with the apparatus 1 can be reduced, and the cost can be reduced. Furthermore, even if the total load current exceeds a predetermined maximum current value, the functions of the loads LD1 to LDm can be prevented from suddenly stopping.

Next, FIG. 2 is a diagram illustrating circuit examples of the DC constant voltage circuit CVk (k = 1 to m) and the load current detection circuit DTk.
In FIG. 2, the DC constant voltage circuit CVk is a series regulator, and the output voltage Vok is divided by a resistor 21 and a resistor 22, and the divided voltage Vd and a reference voltage generation circuit 23 generate and output a predetermined voltage. A difference voltage with respect to the reference voltage Vr is amplified by the error amplifier 24. In the error amplifier 24, the divided voltage Vd is input to the non-inverting input terminal, the reference voltage Vr is input to the inverting input terminal, and the output terminal is for output control including a P-channel MOS transistor (hereinafter referred to as a PMOS transistor). The output control transistor 25 is connected to the gate of the transistor 25 and controls the operation of the output control transistor 25 so that the output voltage Vok becomes constant at a desired voltage. Further, the operation of the error amplifier 24 is controlled by the control signal Sk from the load current control circuit 3.

  On the other hand, the load current detection circuit DTk is formed by a load current detection transistor 28 made of a PMOS transistor and a resistor 29, and a series circuit of the load current detection transistor 28 and the resistor 29 between the input voltage Vik and the ground voltage. Is connected. The gate of the load current detection transistor 28 is connected to the output terminal of the error amplifier 24 of the DC constant voltage circuit CVk. As described above, the load current detection transistor 28 has a gate and a source connected to correspond to the gate and the source of the output control transistor 25.

  The chip area of the load current detection transistor 28 is formed to be smaller than the chip area of the output control transistor 25. Therefore, the current flowing through the load current detection transistor 28 is smaller than the current flowing through the voltage control transistor 25 and becomes a value proportional to the current flowing through the voltage control transistor 25. For this reason, the current flowing through the voltage control transistor 25 can be known by detecting the current flowing through the load current detection transistor 28.

  Further, in FIG. 1, the DC constant voltage circuits CV1 to CVm, the load current detection circuits DT1 to DTm, and the load current processing circuit 2 are integrated and formed in a one-chip IC, thereby further saving power and space. Can do. Further, since the maximum allowable current value of the semiconductor chip constituting the IC can be made equal to or less than the sum of the maximum values of the load currents, the chip area can be reduced and the cost can be reduced.

  As described above, the power supply device in the first embodiment detects the currents IL1 to ILm output from the DC constant voltage circuits CV1 to CVm to the corresponding loads LD1 to LDm by the load current detection circuits DT1 to DTm, respectively. The load current control circuit 3 reduces the current consumption in order from the load with the lowest priority in the loads LD1 to LDm when the total sum of the detected current values exceeds a preset current value. did. From this, even when the sum of the load currents for each load exceeds a predetermined value, the sum of the load currents can be made to be less than the predetermined value while continuing the operation of each load.

Second embodiment.
In the first embodiment, the current consumption for the loads LD1 to LDm is reduced by the load current control circuit 3 including the CPU. The operation of the load current control circuit 3 is performed by the load current processing circuit 2 as described above. This may be performed in the second embodiment of the present invention.
FIG. 3 is a block diagram showing an example of a power supply apparatus according to the second embodiment of the present invention. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, the description thereof is omitted here, and only differences from FIG. 1 are described.

3 is different from FIG. 1 in that the load current processing circuit 2 of FIG. 1 is provided with a load current control circuit 33 including a sequencer and an arithmetic circuit. Accordingly, the load current processing circuit 2 of FIG. Is the load current processing circuit 32, and the power supply device 1 of FIG. 1 is the power supply device 31.
In FIG. 3, the power supply device 31 includes DC constant voltage circuits CV1 to CVm, load current detection circuits DT1 to DTm, and load currents IL1 to ILm detected by the load current detection circuits DT1 to DTm. And a load current processing circuit 32 for controlling the load current consumed by the loads LD1 to LDm.

  The load current processing circuit 32 sequentially converts each current value indicated by each signal input from the load current detection circuits DT1 to DTm into digital data, and calculates the sum of the load currents IL1 to ILm. Further, the calculated total sum of load currents is compared with a preset maximum current value. When the sum of the load currents is larger than the maximum current value, the current consumption of the load with the lowest priority among the currently connected loads LD1 to LDm is reduced. As a method for reducing the current consumption, when the operation of the corresponding load may be stopped, the operation of the load is stopped.

  Further, when the operation of the corresponding load cannot be stopped, the load current processing circuit 32 reduces the consumption current according to the type of the load. For example, when the load is operating based on the clock signal, the load current processing circuit 32 reduces the frequency of the clock signal to reduce the current consumption of the load. For example, when the load is illumination such as an LED, the load current processing circuit 32 reduces the luminance of the illumination to reduce current consumption. Thus, even if such a consumption current reduction method is performed for the load having the lowest priority, if the sum of the load currents IL1 to ILm is still larger than the maximum current value, the load current processing circuit 32 is second. Reduce current consumption for low priority loads. In this way, the load current processing circuit 32 reduces the current consumption of the load until the sum of the load currents becomes smaller than the predetermined maximum current value.

  Here, the load current processing circuit 32 is consumed by the multiplexer 11, the A / D converter 12, the control circuit 13, the storage circuit 14, and the loads LD1 to LDm according to the obtained load currents IL1 to ILm. And a load current control circuit 33 including a sequencer and an arithmetic circuit for controlling the load currents IL1 to ILm. The load current processing circuit 32 forms a load current control circuit unit. Further, the control operation of the load currents IL1 to ILm by the load current control circuit 33 is the same as that of the load current control circuit 3 of FIG.

  As described above, since the power supply apparatus according to the second embodiment is provided with the load current control circuit 33 in the load current processing circuit 32, the same effect as the first embodiment can be obtained. In addition, the DC constant voltage circuits CV1 to CVm, the load current detection circuits DT1 to DTm, and the load current processing circuit 32 are integrated and formed in a one-chip IC, thereby further saving power and space. . Further, since the maximum allowable current value of the semiconductor chip constituting the IC can be made equal to or less than the sum of the maximum values of the load currents, the chip area can be reduced and the cost can be reduced.

Third embodiment.
In each of the first and second embodiments, the current consumption is reduced in order from the load with the lowest priority determined in advance in the loads LD1 to LDm, but depending on the state of the loads LD1 to LDm. The priority order may be changed, and this is the third embodiment of the present invention.
The block diagram showing an example of the power supply apparatus in the third embodiment of the present invention is different from the operation of the load current control circuit 3 in FIG. Since the control circuit 3a is the same as that of FIG. 1 except that the power supply device 1 of FIG.

When the sum of the current values detected by the load current detection circuits DT1 to DTm exceeds a preset current value α, the load current control circuit 3a applies the load LD1 to LDm according to the state of the loads LD1 to LDm. On the other hand, current consumption is reduced and operation control of the DC constant voltage circuits CV1 to CVm is performed. The load current control circuit 3a can operate each of the DC constant voltage circuits CV1 to CVm in the low current consumption operation mode in which the operation is stopped or the current consumption is reduced.
FIG. 4 is a flowchart showing an operation example of the load current control circuit 3a. The operation of the load current control circuit 3a will be described in more detail with reference to FIG.

  In FIG. 4, first, the load current control circuit 3a reads the respective data indicating the current values of the load currents IL1 to ILm from the storage circuit 14 and calculates the sum of the load currents IL1 to ILm (step ST1). . Next, the load current control circuit 3a checks whether or not the total sum of the calculated currents exceeds the predetermined value α (step ST2). If the total value does not exceed the predetermined value α (NO), the process returns to step ST1, When the value α is exceeded (YES), it is checked whether or not there is a DC constant voltage circuit in which the corresponding load does not consume current among the DC constant voltage circuits CV1 to CVm (step ST3). If there is a DC constant voltage circuit in which the corresponding load does not consume current in step ST3 (YES), the load current control circuit 3a stops the operation of the corresponding DC constant voltage circuit (step ST4). Return to step ST1.

  The load current control circuit 3a operates in the low current consumption operation mode among the DC constant voltage circuits CV1 to CVm when there is no DC constant voltage circuit in which the corresponding load does not consume current in step ST3 (NO). It is checked whether or not there is a DC low voltage circuit that can be operated (step ST5). When there is a DC constant voltage circuit that can be operated in the low current consumption operation mode in step ST5 (YES), the load current control circuit 3a operates the corresponding DC constant voltage circuit in the low current consumption operation mode. (Step ST6), it returns to step ST1. If there is no DC constant voltage circuit that can be operated in the low current consumption operation mode in step ST5 (NO), the load current control circuit 3a may reduce the frequency of the clock signal among the loads LD1 to LDm. It is checked whether or not there is a load that can be performed (step ST7).

  When there is a load that can reduce the frequency of the clock signal in step ST7 (YES), the load current control circuit 3a reduces the frequency of the clock signal of the corresponding load (step ST8) and goes to step ST1. Return. When there is no load capable of lowering the frequency of the clock signal in step ST7 (NO), the load current control circuit 3a reduces the current consumption by reducing the luminance of the LEDs among the loads LD1 to LDm. It is checked whether there is a load that can be performed (step ST9). When there is a load that can reduce the current consumption in step ST9 (YES), the load current control circuit 3a reduces the current consumption with respect to the corresponding load (step ST10), and returns to step ST1. In step ST9, when there is no load capable of reducing current consumption (NO), the process returns to step ST1.

  In this way, the load current control circuit 3a controls the operations of the DC constant voltage circuits CV1 to CVm and the loads LD1 to LDm in accordance with the calculated sum of the load currents IL1 to ILm.

  In the above description, the power supply device having the configuration in the first embodiment has been described as an example. However, the third embodiment is also applied to the power supply device having the configuration in the second embodiment. It goes without saying that you can do it. When the third embodiment is applied to the power supply device of the second embodiment, the block diagram showing an example of the power supply device in the third embodiment of the present invention is the load shown in FIG. Since the operation of the current control circuit 33 is different, the load current control circuit 33 in FIG. 3 is changed to the load current control circuit 33a and the power supply device 31 in FIG. 3 is changed to the power supply device 31a. I will omit it. The load current control circuit 33a performs the same operation as the load current control circuit 3a, and the flowchart showing an example of the operation of the load current control circuit 33a replaces the load current control circuit 3a of FIG. 4 with the load current control circuit 33a. Except for this, it is the same as FIG.

  As described above, in the power supply device according to the third embodiment, the load current control circuit causes the sum of the current values detected by the load current detection circuits DT1 to DTm to be greater than or equal to the preset current value α. In this case, current consumption is reduced for the loads LD1 to LDm in accordance with the states of the loads LD1 to LDm, and operation control of the DC constant voltage circuits CV1 to CVm is performed. Thus, the same effects as those of the first and second embodiments can be obtained, and when the current consumption of the device is close to the set maximum current, the performance of the device is slightly reduced but consumed. Electric power can be reduced, and the size and cost of the device can be reduced. Furthermore, even when the maximum current is exceeded as in the prior art, it is possible to prevent the function of the device from suddenly stopping.

  In the first to third embodiments, the loads LD1 to LDm may each function in one device.

It is the block diagram which showed the example of the power supply device in the 1st Embodiment of this invention. It is the figure which showed the circuit example of direct current | flow constant voltage circuit CVk and load current detection circuit DTk. It is the block diagram which showed the example of the power supply device in the 2nd Embodiment of this invention. It is the flowchart which showed the operation example of the power supply device in the 3rd Embodiment of this invention. It is the block diagram which showed the example of the conventional power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 Power supply device 2,32 Load current processing circuit 3,33 Load current control circuit 10 DC power supply 11 Multiplexer 12 A / D converter 13 Control circuit CV1-CVm DC constant voltage circuit DT1-DTm Load current detection circuit LD1-LDm load

Claims (6)

In a power supply device for supplying power to a plurality of loads, including a plurality of DC constant voltage circuits that generate a predetermined constant voltage from a power supply voltage from a DC power source and output the generated constant voltage to a corresponding load.
A load current detection circuit unit that detects each current output from each DC constant voltage circuit to a corresponding load, and generates and outputs a signal indicating each detected current value;
The sum of the output currents of the DC constant voltage circuits is calculated from the current values indicated by the output signals from the load current detection circuit unit. When the calculated current sum exceeds a predetermined value, A load current control circuit unit for controlling the operation of each DC constant voltage circuit and each load so that the sum of output currents of the constant voltage circuit is less than or equal to the predetermined value;
A power supply device comprising:   The load current control circuit unit is preset for each load such that when the calculated sum of currents exceeds a predetermined value, the sum of output currents of the DC constant voltage circuits is less than or equal to the predetermined value. 2. The power supply device according to claim 1, wherein the current consumption is reduced in accordance with the order.   The load current control circuit unit reduces the current consumption for a load capable of reducing the current consumption according to the state of the load when the total sum of the calculated currents exceeds a predetermined value. The power supply device according to claim 1. The load current control circuit unit is
A load current processing circuit that converts each current value indicated by each output signal from the load current detection circuit unit into a digital signal and outputs the digital signal;
From each signal output from the load current processing circuit, the sum of output currents of the DC constant voltage circuits is calculated, and when the calculated sum of currents exceeds a predetermined value, the output current of the DC constant voltage circuits A load current control circuit that reduces the current consumption for each of the loads so that the sum of
Consists of
4. The power supply device according to claim 1, wherein each of the DC constant voltage circuits, the load current detection circuit unit, and the load current processing circuit are integrated in a single IC.   4. The power supply device according to claim 1, wherein each of the DC constant voltage circuits, the load current detection circuit unit, and the load current control circuit unit are integrated into one IC. A signal indicating each detected current value by detecting each current output to each load from a plurality of DC constant voltage circuits that generate a predetermined constant voltage from the power supply voltage from the DC power supply and output it to the corresponding load Load current detection circuit section for generating and outputting each of the load current control circuit, and load current control for controlling the operation of each DC constant voltage circuit and each load from each current value indicated by each output signal from the load current detection circuit section In a power supply method of a power supply device comprising a circuit unit,
Calculate the sum of each current detected by the load current detection circuit unit,
When the calculated sum of currents exceeds a predetermined value, the current consumption is reduced in accordance with a preset order for each load so that the sum of output currents of the DC constant voltage circuits is equal to or less than the predetermined value. A power supply method characterized by reducing.

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