JP2009157820A - Power unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently supply voltage to a plurality of loads. <P>SOLUTION: A virtual supply voltage generation circuit 50 steps down predetermined supply voltage to generate predetermined fixed voltage. The supply voltage is applied to a high potential side terminal of a first series regulator 10. A low potential side terminal of the first series regulator 10 is connected to a high potential side terminal of a first load to the low potential side terminal of which the fixed voltage generated by the virtual supply voltage generation circuit 50 is applied. The fixed voltage generated by the virtual supply voltage generation circuit 50 is applied to a high potential side terminal of a second series regulator 20. A low potential side terminal of the second series regulator 20 is connected to a high potential side terminal of a second load to the low potential side terminal of which ground voltage is applied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply apparatus that performs DC-DC conversion on a power supply voltage supplied from a battery or the like.

  Mobile devices such as mobile phones and portable music players have become widespread. In such a portable device, many digital elements such as a processor and a memory, and many analog elements such as a sound source circuit and an analog / digital converter are mounted. Since the operating voltages of these many elements are different from each other, it is necessary to convert the power supply voltage supplied from the battery into various levels of voltage. For this purpose, a plurality of DC-DC converters and resistors are provided in parallel with respect to the power supply voltage supplied from the battery to generate a plurality of voltages suitable for each element.

Patent Document 1 discloses a semiconductor circuit. The semiconductor circuit includes a first logic circuit and a second logic circuit, a power supply having a potential Vdd from the ground level, a virtual power supply line, and means for maintaining the potential of the virtual power supply line at approximately Vdd / 2. . Power supply to the first logic circuit is performed from the ground and the virtual power supply, and power supply to the second logic circuit is performed from the virtual power supply line and the power supply having the potential Vdd.
JP 2000-349603 A

  As a matter of course, when a voltage is stepped down by a DC-DC converter or a resistor, a current flows through them and power is consumed. As described above, when a plurality of DC-DC converters and resistors are arranged in parallel with respect to the power supply voltage supplied from the battery, power consumption increases. As energy conservation is promoted, efficient power supply with low power consumption is required. In particular, battery-powered portable devices are strongly required to reduce power consumption from the viewpoint of securing driving time.

  This invention is made | formed in view of such a condition, The objective is to provide the power supply device which can supply a voltage efficiently with respect to several load.

  A power supply device according to an aspect of the present invention includes a step-down circuit that steps down a predetermined power supply voltage to generate a predetermined fixed voltage, a first voltage control unit that applies the power supply voltage to a high-potential side terminal, and a step-down circuit. A second voltage control unit that applies the generated fixed voltage to the high-potential side terminal. The low potential side terminal of the first voltage control unit is connected to the high potential side terminal of the first load to which a fixed voltage is applied to the low potential side terminal, and the low potential side terminal of the second voltage control unit is connected to the low potential side The terminal is connected to the high potential side terminal of the second load to which a ground voltage is applied.

  According to the present invention, a voltage can be efficiently supplied to a plurality of loads.

FIG. 1 is a diagram illustrating a configuration of a power supply device 100 according to the first embodiment.
The power supply apparatus 100 includes a virtual power supply voltage generation circuit 50, a first series regulator 10, and a second series regulator 20. The first series regulator 10 and the second series regulator 20 are used as an example of a voltage control unit. A detailed circuit configuration example of these components will be described later. In FIG. 1, the first load 30 and the second load 40 are also drawn for convenience of explanation, but the first load 30 and the second load 40 are not used as components of the power supply device 100.

  The virtual power supply voltage generation circuit 50 has a high potential side terminal connected to the power supply line, and a low potential side terminal connected to the low potential side terminal of the first load 30 and the high potential side terminal of the second series regulator 20. The virtual power supply voltage generation circuit 50 acts as a step-down circuit that steps down a predetermined power supply voltage Vdd to generate a predetermined fixed voltage. This power supply voltage Vdd may be supplied from a battery (not shown). This fixed voltage is used as a virtual power supply voltage viewed from the second load 40.

  The first series regulator 10 has a high potential side terminal connected to the power supply line and a low potential side terminal connected to the high potential side terminal of the first load 30. The first series regulator 10 steps down the power supply voltage Vdd applied to the high potential side terminal and applies it to the first load 30.

  In the second series regulator 20, the high potential side terminal is connected to the low potential side terminal of the first load 30 and the low potential side terminal of the virtual power supply voltage generation circuit 50, and the low potential side terminal is connected to the high potential side of the second load 40. Connected to the terminal. The second series regulator 20 steps down the fixed voltage generated by the virtual power supply voltage generation circuit 50 and applies it to the second load 40.

  The first load 30 has a high potential side terminal connected to the low potential side terminal of the first series regulator 10, and a low potential side terminal connected to the low potential side terminal of the virtual power supply voltage generation circuit 50 and the high potential of the second series regulator 20. Connected to the side terminal. The first load 30 operates by receiving the voltage obtained by stepping down the power supply voltage Vdd by the first series regulator 10 and the fixed voltage generated by the virtual power supply voltage generation circuit 50 at both terminals.

  The second load 40 has a high potential side terminal connected to the low potential side terminal of the second series regulator 20 and a low potential side terminal connected to the ground line. The second load 40 operates by receiving the voltage obtained by stepping down the fixed voltage by the second series regulator 20 and the ground voltage at both terminals.

FIG. 2 is a diagram showing a configuration of a general power supply device 150 to be compared with the power supply device 100 according to the first embodiment.
The first series regulator 10 steps down the power supply voltage Vdd and supplies it to the high potential side terminal of the first load 30. The second series regulator 20 steps down the power supply voltage Vdd and supplies it to the high potential side terminal of the second load 40. The low potential side terminals of the first load 30 and the second load 40 are connected to the ground line.

  Hereinafter, the power consumption of the power supply apparatus 100 shown in FIG. 1 and the power supply apparatus 150 shown in FIG. 2 will be compared. In the following example, it is assumed that the operating voltage of the first load 30 is 1/4 Vdd, the operating voltage of the second load 40 is 3/8 Vdd, and the fixed voltage output from the virtual power supply voltage generation circuit 50 shown in FIG. 1 is 7/16 Vdd. To do.

In the power supply device 150 shown in FIG. 2, the current Ia flowing through the first series regulator 10 and the first load 30 and the current Ib flowing through the second series regulator 20 and the second load 40 are expressed by the following formulas 1 and 2.
Ia = Vdd / (resistance component of first series regulator 10 + resistance component of first load 30) (Equation 1)
Ib = Vdd / (resistance component of second series regulator 20 + resistance component of second load 40) (Equation 2)

On the other hand, in the power supply device 100 shown in FIG. 1, the current Ia flowing through the first series regulator 10 and the first load 30 and the current Ib flowing through the second series regulator 20 and the second load 40 are expressed by the following equations 3 and 4. .
Ia = (7 / 16Vdd) / (resistance component of second series regulator 20 + resistance component of second load 40) (Equation 3)
Ib = (9 / 16Vdd) / (resistance component of first series regulator 10 + resistance component of first load 30) (Equation 4)

  As described above, when the same current flows between the power supply device 100 shown in FIG. 1 and the power supply device 150 shown in FIG. 2, the resistance components of the first series regulator 10 and the second series regulator 20 can be reduced, and the circuit The area can be reduced. Further, the power consumed by the first series regulator 10 and the second series regulator 20, that is, the power loss can be reduced by the amount of the resistance component being small.

Hereinafter, the power supply apparatus 100 illustrated in FIG. 1 will be described in more detail.
FIG. 3 is a diagram illustrating a circuit configuration example of the power supply device 100 according to the first embodiment. FIG. 3 shows an example in which the virtual power supply voltage generation circuit 50 is configured by a regulator. In FIG. 3, the first load 30 is depicted as a parallel equivalent circuit of a first equivalent resistor R31 and a first equivalent capacitor C31, and the second load 40 is depicted as a parallel equivalent circuit of a second equivalent resistor R41 and a second equivalent capacitor C41.

The virtual power supply voltage generation circuit 50 includes a first comparator CP51, a second comparator CP52, a first P-channel transistor M51, an N-channel transistor M52, and a first capacitor C51.
The first reference voltage ref51 is applied to the inverting input terminal of the first comparator CP51. The second reference voltage ref52 is applied to the inverting input terminal of the second comparator CP52. The second reference voltage ref52 is set to a voltage higher than the first reference voltage ref51. The first reference voltage ref51 and the second reference voltage ref52 can be generated by resistance-dividing the power supply voltage Vdd.

  The non-inverting input terminal of the first comparator CP51 and the non-inverting input terminal of the second comparator CP52 are a low-potential side terminal of the first load 30 and a high-potential side terminal of the second series regulator 20 (hereinafter, a connection point between both terminals is defined). Connected to the first node N1). The output terminal of the first comparator CP51 is connected to the gate terminal of the first P-channel transistor M51. The output terminal of the second comparator CP52 is connected to the gate terminal of the N-channel transistor M52.

  The first comparator CP51 compares the first reference voltage ref51 with a voltage at a fourth node N4 described later, and outputs a high level signal or a low level signal to the gate terminal of the first P-channel transistor M51 according to the result. . The second comparator CP52 compares the second reference voltage ref52 with a voltage at a fourth node N4 described later, and outputs a high level signal or a low level signal to the gate terminal of the N channel transistor M52 according to the result.

  The first P-channel transistor M51 may employ a P-channel type MOSFET. The source terminal of the first P-channel transistor M51 is connected to the power supply line, the gate terminal is connected to the output terminal of the first comparator CP51, and the drain terminal is connected to the drain terminal of the N-channel transistor M52.

  The N-channel transistor M52 can employ an N-channel type MOSFET. The N channel transistor M52 has a source terminal connected to the ground line, a gate terminal connected to the output terminal of the second comparator CP52, and a drain terminal connected to the drain terminal of the first P channel transistor M51.

  Both drain terminals of the first P-channel transistor M51 and the N-channel transistor M52 (hereinafter, a connection point between both terminals is referred to as a fourth node N4) are both non-inverting input terminals of the first comparator CP51 and the second comparator CP52, and the first Connected to node N1. A first capacitor C51 is connected between the node between the fourth node N4 and the first node N1 and the ground line. The first capacitor C51 smoothes the voltage at the fourth node N4.

  The virtual power supply voltage generation circuit 50 having such a configuration acts to fix the voltage while supplying a voltage obtained by stepping down the power supply voltage Vdd to the first node N1. That is, when the voltage of the fourth node N4 in the previous stage of the first node N1 is the target voltage to be fixed, the first comparator CP51 outputs a high level signal, the first P-channel transistor M51 is in the OFF state, The comparator CP52 outputs a low level signal, and the N-channel transistor M52 is off.

  On the other hand, when the voltage of the fourth node N4 becomes higher than the target voltage, the output signal of the second comparator CP52 transits to a high level, and the N-channel transistor M52 is turned on. Thereby, the electric charge of 4th node N4 can be discharged, and the voltage of 4th node N4 can be reduced.

  On the other hand, when the voltage at the fourth node N4 becomes lower than the target voltage, the output signal of the first comparator CP51 transits to a low level, and the first P-channel transistor M51 is turned on. As a result, the fourth node N4 can be charged, and the voltage of the fourth node N4 can be increased.

The first series regulator 10 includes a third comparator CP11 and a second P-channel transistor M11. The second series regulator 20 includes a fourth comparator CP21 and a third P-channel transistor M21.
The third reference voltage ref11 is applied to the inverting input terminal of the third comparator CP11. The fourth reference voltage ref21 is applied to the inverting input terminal of the fourth comparator CP21. The third reference voltage ref11 is set higher than the fourth reference voltage ref21. The third reference voltage ref11 and the fourth reference voltage ref21 can be generated by resistance-dividing the power supply voltage Vdd.

The non-inverting input terminal of the third comparator CP11 is connected to the high potential side terminal of the first load 30 and the drain terminal of the second P-channel transistor M11 (hereinafter, the coupling point of both terminals is referred to as the second node N2). The output terminal of the third comparator CP11 is connected to the gate terminal of the second P-channel transistor M11.
The second P-channel transistor M11 has a source terminal connected to the power supply line, a gate terminal connected to the output terminal of the third comparator CP11, and a drain terminal connected to the second node N2.

The non-inverting input terminal of the fourth comparator CP21 is connected to the high potential side terminal of the second load 40 and the drain terminal of the third P-channel transistor M21 (hereinafter, the coupling point of both terminals is referred to as a third node N3). The output terminal of the fourth comparator CP21 is connected to the gate terminal of the third P-channel transistor M21.
The source terminal of the third P-channel transistor M21 is connected to the first node N1, its gate terminal is connected to the output terminal of the fourth comparator CP21, and its drain terminal is connected to the third node N3.

  The first series regulator 10 having such a configuration fixes the voltage of the second node N2 to the third reference voltage ref11 while supplying the voltage obtained by stepping down the power supply voltage Vdd to the high potential side terminal of the first load 30. Drive like so. That is, when the voltage of the second node N2 is higher than the target voltage to be fixed (third reference voltage ref11), the third comparator CP11 outputs a high level signal, and increases the resistance component of the second P-channel transistor M11. The voltage of the second node N2 is reduced. On the other hand, when the voltage of the second node N2 is smaller than the target voltage to be fixed (third reference voltage ref11), the third comparator CP11 outputs a low level signal, lowering the resistance component of the second P-channel transistor M11, The voltage of the second node N2 is increased. The second series regulator 20 also operates in the same manner as the first series regulator 10 with respect to the third node N3.

FIG. 4 is a diagram showing a simulation result of the power supply apparatus 100 shown in FIG.
FIG. 4 shows an example when the power supply voltage is set to 4.8V. It can be seen that the voltage at the first node N1 is stably fixed at 2.4V, the voltage at the second node N2 is 3.6V, and the voltage at the third node N3 is 1.2V. It can be seen that the voltage {(the voltage at the second node N2) − (the voltage at the first node N1)} that is stepped down by the first load 30 is also stably fixed at 1.2V.

  As described above, according to the first embodiment, a voltage can be efficiently supplied to a plurality of loads. That is, the power consumption can be reduced or the circuit scale can be reduced as compared with the case where a DC-DC converter or a resistor is connected in parallel between the power supply voltage and each load. As described with reference to FIG. 2, a voltage can be supplied with high efficiency to a plurality of loads operating at different voltages. The sum of the operating voltages of the loads does not need to match the power supply voltage.

  The fixed voltage generated as a virtual power supply voltage is not limited to 1/2 of the power supply voltage Vdd, and can be set to an arbitrary value. Further, by providing the first series regulator 10 and the second series regulator 20, it is possible to further adjust the fixed voltage and supply the voltage to the first load 30 and the second load 40. Further, by using the first series regulator 10 and the second series regulator 20, it is possible to supply a stable voltage to the first load 30 and the second load 40.

FIG. 5 is a diagram illustrating a configuration of an electronic device 200 on which the power supply device 110 according to the second embodiment is mounted. The electronic device 200 is assumed to be a mobile device such as a mobile phone. Of course, the device is not limited to a portable device as long as it is a battery-driven device.
Electronic device 200 includes a battery 500, a power supply device 110, a first load 30, and a second load 40. As the battery 500, a lithium ion battery or the like can be used. The battery 500 supplies a power supply voltage to the power supply device 110. This power supply voltage is 3.6 V in the example of FIG.

  In the second embodiment, a digital load is assumed as the first load 30, and an analog load is assumed as the second load 40. In FIG. 5, the memory 31, CPU 32, and logic circuit 33 are assumed as digital loads, and an RF circuit (high frequency circuit) 41, an ADC (analog / digital converter) 42, and a sound source circuit 43 are assumed as analog loads.

  The power supply device 110 includes a virtual power supply voltage generation circuit 50, a first series regulator 10, a second series regulator 20, a control circuit 60, a first switch S11, and a second switch S12. Although the first switch S11 is drawn outside the frame of the power supply device 110 in FIG. 5, the first switch S11 is also considered as a component of the power supply device 110.

The virtual power supply voltage generation circuit 50 reduces the power supply voltage supplied from the battery 500 to generate the fixed voltage. In the example of FIG. 5, it is 2.3V.
The first series regulator 10 converts a power supply voltage into voltages to be supplied to the memory 31, the CPU 32, and the logic circuit 33, respectively. The first series regulator a11, the first series regulator b12, and the first series regulator c13 (FIG. 5, 6 is a series regulator). In the example of FIG. 5, the first series regulator a11, the first series regulator b12, and the first series regulator c13 convert 3.6V into 3.5V, 3.2V, and 3.3V, respectively. The voltages in parentheses indicate the operating voltages of the memory 31, CPU 32, and logic circuit 33. When these low potential terminals are connected to the ground line, the voltages to be supplied to those high potential terminals. Is shown.

  The second series regulator 20 includes a second series regulator a21, a second series regulator b22, and a second series regulator c23 for converting the fixed voltage into voltages supplied to the RF circuit 41, the ADC 42, and the sound source circuit 43, respectively. Prepare. In the example of FIG. 5, the second series regulator a21, the second series regulator b22, and the second series regulator c23 convert 2.3V to 2.0V, 1.5V, and 1.8V, respectively.

  The first switch S11 switches which of the fixed voltage and the ground voltage is applied to the low potential side terminal of the first load 30. The second switch S12 switches which of the fixed voltage and the power supply voltage is applied to the high potential side terminal of the second load 40.

The control circuit 60 controls the first switch S11 and the second switch S12 according to the level of the power supply voltage.
More specifically, when the level of the power supply voltage exceeds a predetermined threshold, the first switch S11 is controlled to apply the fixed voltage to the low potential side terminal of the first load 30, and the high potential of the second load 40 is controlled. The second switch S12 is controlled to apply the fixed voltage to the side terminal. On the other hand, when the level of the power supply voltage does not exceed a predetermined threshold, the first switch S11 is controlled to apply the power supply voltage to the low potential side terminal of the first load 30 and the power supply to the high potential side terminal of the second load 40 is supplied. The second switch S12 is controlled to apply the voltage.

  That is, when the level of the power supply voltage exceeds a predetermined threshold, the first series regulator 10, the first load 30, the second series regulator 20, and the second load 40 are configured in series as shown in FIG. A power supply voltage is applied to the series regulator 10, and control is performed so that the fixed voltage is applied to the connection point between the first load 30 and the second series regulator 20. On the other hand, when the level of the power supply voltage does not exceed a predetermined threshold, the series circuit of the first series regulator 10 and the first load 30 and the second series regulator 20 and the second load 40 as shown in FIG. A series circuit is configured in parallel, and the first series regulator 10 and the second series regulator 20 are controlled to supply the power supply voltage in parallel.

  The threshold value is a threshold value for detecting the degree of consumption of the battery 500. Values obtained by the designer through experiments and simulations can be used. In the example of FIG. 5, it is preferable to set any value within the range of 2.3 to 3.5V. Within the range, a higher voltage may be set when priority is given to accuracy, and a lower voltage may be set when priority is given to power consumption.

  FIG. 6 is a diagram illustrating a configuration of an electronic device 250 including a general power supply device 160 to be compared with the electronic device 200 including the power supply device 110 according to the second embodiment. Since the basic configuration is the same as that of the electronic device 200 on which the power supply device 110 according to the second embodiment is mounted, differences will be described below.

  The power supply device 160 does not include the control circuit 60, the first switch S11, and the second switch S12. Instead, two switching regulators 53 and 54 are included. The switching regulator 53 steps down the power supply voltage supplied from the battery 500 and generates a voltage to be supplied to the digital system load 30. In FIG. 6, 3.6V is converted to 1.5V. The switching regulator 54 steps down the power supply voltage supplied from the battery 500 and generates a voltage to be supplied to the analog load 40. In FIG. 6, 3.6V is converted to 2.5V.

  The high potential side terminal of the first load 30 is connected to the system of the switching regulator 53, and the low potential side terminal is fixed to the ground line. The high potential side terminal of the second load 40 is connected to the system of the switching regulator 54, and the low potential side terminal is fixed to the ground line. These circuit forms are fixed.

  As described above, according to the second embodiment, the circuit configuration that can be changed from the circuit configuration shown in FIG. 1 to the circuit configuration shown in FIG. It is possible to achieve both a request for securing. That is, although the circuit configuration shown in FIG. 1 can reduce power consumption, it becomes difficult to ensure the operation accuracy of the load when the power supply voltage supplied from the battery decreases. In that case, the operation accuracy of the load can be ensured by switching to the circuit configuration shown in FIG.

  Note that there is also a method of reducing power consumption by configuring the virtual power supply voltage generation circuit 50 shown in FIG. 5 with a switching regulator. However, it is necessary to use a passive element such as a coil, resulting in an increase in circuit area and cost. There is also a problem of noise generated from the coil.

  Next, a third embodiment will be described. The power supply device 120 according to Embodiment 2 can switch between a circuit configuration in which two types of load units are connected in series and a circuit configuration in which they are connected in parallel. The power supply device according to Embodiment 3 is generalized to Embodiment 2, and can switch between a circuit configuration in which a plurality of types of load units are connected in series and a circuit configuration in which they are connected in parallel. After the general description, an example in which a circuit configuration in which three types of load sections are connected in series and a circuit configuration in which they are connected in parallel will be described with reference to FIGS.

The power supply device according to Embodiment 3 includes a plurality of step-down circuits, a plurality of switches, and a control unit.
The plurality of step-down circuits step down a predetermined power supply voltage and generate fixed voltages of different levels. The plurality of switches switches which of the power supply voltage, one of the fixed voltages generated by the plurality of step-down circuits, and one of the ground voltages is supplied to both terminals of each load unit.

The control unit controls the plurality of switches according to the level of the power supply voltage.
More specifically, when the level of the power supply voltage is less than a predetermined first threshold, the plurality of switches are controlled so as to supply the power supply voltage and the ground voltage to both terminals of all the load units.
Further, the control unit may change the load unit that supplies the power supply voltage and the ground voltage in accordance with the operating status of the plurality of load units.

Here, the load unit is a concept including a load and a voltage control unit such as a series regulator connected in series to the preceding stage. Depending on the operating voltage of the load, a configuration in which no voltage control unit is connected to the preceding stage is possible.
The first threshold value is a threshold value for detecting the degree of battery consumption. Values obtained by the designer through experiments and simulations can be used.

FIG. 7 is a diagram illustrating a first state of one configuration example in the electronic apparatus 300 on which the power supply device according to the third embodiment is mounted.
In the example of FIG. 7, the plurality of load units are classified into a first load unit, a second load unit group, and a third load unit group. The second load unit group includes a second load unit A81 and a second load unit B82, and the third load unit group includes a third load unit A91, a third load unit B92, and a third load unit C93.

  As these load units, for example, the following configuration example can be assumed. That is, the digital system load 30 shown in FIG. 5 is classified into two, and the first load unit 71 and the second load unit group shown in FIG. The first load unit 71 corresponds to the first series regulator a11 and the memory 31, the second load unit A81 corresponds to the first series regulator b12 and the CPU 32, and the second load unit B82 includes the first series regulator c13 and the logic circuit 33. It shall correspond to. The third load unit A91 corresponds to the second series regulator a21 and the RF circuit 41, the third load unit B92 corresponds to the second series regulator b22 and the ADC 42, and the third load unit C93 includes the second series regulator c23 and the sound source circuit. It shall correspond to 43.

In the example of FIG. 7, the power supply voltage supplied from the battery 500 is 6.0V.
The virtual power supply voltage generation circuit A51 generates a first fixed voltage by stepping down the power supply voltage. In the example of FIG. The virtual power supply voltage generation circuit B52 generates a second fixed voltage by stepping down the power supply voltage. In the example of FIG.

  The first switch S31 switches between the power supply voltage and the high impedance. The second switch S32 switches between the power supply voltage and the first fixed voltage. The third switch S33 switches between the second fixed voltage and the ground voltage. The fourth switch S34 switches between ground voltage and high impedance.

  The fifth switch S35 switches the path so that the power supply voltage is constantly applied to the high potential side terminal of the first load section 71. The sixth switch S36 switches whether the first fixed voltage, the second fixed voltage, or the ground voltage is applied to the low potential side terminal of the first load unit 71. The seventh switch S37 switches whether the first fixed voltage or the power supply voltage is applied to the high potential side terminal of the second load unit B82. The eighth switch S38 switches whether the second fixed voltage or the ground voltage is applied to the low potential side terminal of the second load unit B82.

  The ninth switch S39 switches whether the second fixed voltage or the power supply voltage is applied to the high potential side terminal of the third load unit A91. The tenth switch S40 switches the path so that the ground voltage is always applied to the low potential side terminal of the third load part A91. The eleventh switch S41 switches whether the second fixed voltage or the power supply voltage is applied to the high potential side terminal of the third load unit B92. The twelfth switch S42 switches the path so that the ground voltage is constantly applied to the low potential side terminal of the third load unit B92. The thirteenth switch S43 switches whether the second fixed voltage or the power supply voltage is applied to the high potential side terminal of the third load unit C93. The fourteenth switch S44 switches the path so that the ground voltage is constantly applied to the low potential side terminal of the third load unit C93.

  When the level of the power supply voltage exceeds a predetermined second threshold, the control circuit 60 supplies the power supply voltage and the first fixed voltage to both side terminals of the first load unit 71, and the first fixed voltage to both side terminals of the second load unit B82. And the second fixed voltage, and the first to fourteenth switches S31-1 to supply the second fixed voltage and the ground voltage to both terminals of the third load unit A91, the third load unit B92, and the third load unit C93, respectively. S44 is controlled.

  Here, the second threshold value is a threshold value for detecting the degree of battery consumption. Values obtained by the designer through experiments and simulations can be used. The level is set higher than the first threshold. In the example of FIG. 7, the first threshold value is set to about 5.0V, and the second threshold value is set to about 3.6V.

  FIG. 7 depicts a circuit configuration in the case where the power supply voltage is located at about 5.0 to 6.0V. In this state, the control circuit 60 controls the circuit configuration in which three types of loads of the first load unit 71, the second load unit group, and the third load unit group are connected in series. This circuit configuration is the state where the power consumption can be reduced most.

FIG. 8 is a diagram illustrating a second state of one configuration example in the electronic apparatus 300 on which the power supply device according to the third embodiment is mounted.
FIG. 8 depicts a circuit configuration when the power supply voltage is in the range of 3.6 to 6.0V. In this state, the control circuit 60 controls the circuit configuration in which two types of loads of the first load unit 71, the second load unit group, and the third load unit group are connected in series. In this state of the circuit configuration, power consumption increases compared to the circuit state shown in FIG. 7, but power consumption can be reduced from the circuit configuration shown in FIG. 9 in which all the load units are connected in parallel.

FIG. 9 is a diagram illustrating a third state of one configuration example in the electronic apparatus 300 on which the power supply device according to the third embodiment is mounted.
FIG. 9 depicts a circuit configuration when the power supply voltage is in the range of 2.5 to 3.5V. In this state, all the load units of the first load unit 71, the second load unit A81, the second load unit B82, the third load unit A91, the third load unit B92, and the third load unit C93 are connected in parallel. The circuit configuration is controlled by the control circuit 60. In this state of the circuit configuration, power consumption increases most, but even when the battery 500 is exhausted, it is possible to suppress a decrease in operation accuracy for all loads.

FIG. 10 is a diagram illustrating a fourth state of one configuration example in the electronic apparatus 300 on which the power supply device according to the third embodiment is mounted.
FIG. 10 illustrates a circuit configuration when the power supply voltage is 3.6 to 6.0 V and the third load portion A91 is stopped. The information that the third load unit A91 is stopped is transmitted to the control circuit 60 as the load operating status.

  In this state, the first load unit 71 and the second load unit A81, the second load unit B82, the third load unit B92, and the third load unit C93 are connected to the circuit configuration that is connected in series. Controlled by circuit 60. Compared with the circuit configuration shown in FIG. 8, the voltage supply method of the second load unit B82 is changed. As described above, in a situation where the third load part A91 is stopped, it may be better to include the second load part B82 on the low voltage side. Here, the second fixed voltage can be further stabilized.

  As described above, according to the third embodiment, the method of the second embodiment can be extended even when three or more types of loads can be connected in series. Therefore, the same effects as those of the second embodiment are obtained. Furthermore, a more optimal circuit configuration can be realized when the control circuit 60 refers not only to the power supply voltage but also to the operation status of the load.

  The present invention has been described based on some embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

FIG. 11 is a diagram illustrating a modification of the power supply device 100 according to the first embodiment.
The power supply device 100 according to the modification has a configuration in which the first series regulator 10 and the first load 30 of the power supply device 100 illustrated in FIG. This configuration also provides the same effects as those of the first embodiment.

1 is a diagram illustrating a configuration of a power supply device according to a first embodiment. It is a figure which shows the structure of the general power supply device which should be compared with the power supply device which concerns on Embodiment 1. FIG. 2 is a diagram illustrating a circuit configuration example of a power supply device according to Embodiment 1. FIG. It is a figure which shows the simulation result of the power supply device shown in FIG. It is a figure which shows the structure of the electronic device carrying the power supply device which concerns on Embodiment 2. FIG. It is a figure which shows the structure of the electronic device which mounts the general power supply device which should be compared with the electronic device which mounts the power supply device which concerns on Embodiment 2. FIG. It is a figure which shows the 1st state of one structural example in the electronic device carrying the power supply device which concerns on Embodiment 3. FIG. It is a figure which shows the 2nd state of one structural example in the electronic device carrying the power supply device which concerns on Embodiment 3. FIG. It is a figure which shows the 3rd state of the example of 1 structure in the electronic device carrying the power supply device which concerns on Embodiment 3. FIG. It is a figure which shows the 4th state of one structural example in the electronic device carrying the power supply device which concerns on Embodiment 3. FIG. It is a figure which shows the modification of the power supply device which concerns on Embodiment 1. FIG.

Explanation of symbols

  10 first series regulator, 20 second series regulator, 30 first load, 40 second load, 50 virtual power supply voltage generation circuit, 71 first load unit, S11 first switch, S12 second switch, S31 first switch, S32 Second switch, 100 power supply.

Claims (6)

A step-down circuit that steps down a predetermined power supply voltage to generate a fixed voltage;
A first voltage control unit to which the power supply voltage is applied to a high potential side terminal;
A second voltage control unit that applies a fixed voltage generated by the step-down circuit to a high-potential side terminal;
The low potential side terminal of the first voltage control unit is connected to the high potential side terminal of the first load to which the fixed voltage is applied to the low potential side terminal,
The power supply apparatus, wherein the low potential side terminal of the second voltage control unit is connected to a high potential side terminal of a second load to which a ground voltage is applied to the low potential side terminal. A first switch for switching which of the fixed voltage and the ground voltage is applied to a low potential side terminal of the first load;
A second switch for switching which of the fixed voltage and the power supply voltage is applied to a high potential side terminal of the second voltage control unit;
A control unit that controls the first switch and the second switch according to a level of the power supply voltage;
The control unit controls the first switch to apply the fixed voltage to a low potential side terminal of the first load when the level of the power supply voltage exceeds a predetermined threshold, and the second voltage control unit Controlling the second switch to apply the fixed voltage to the high potential side terminal;
When the level of the power supply voltage does not exceed a predetermined threshold value, the first switch is controlled to apply the ground voltage to the low potential side terminal of the first load, and the high potential side terminal of the second voltage control unit The power supply apparatus according to claim 1, wherein the second switch is controlled to apply the power supply voltage to the power supply. A power supply device for supplying voltage to a plurality of load units,
A plurality of step-down circuits that step down a predetermined power supply voltage and generate fixed voltages of different levels;
A plurality of switches for switching which of the two power supply voltages to be supplied to both terminals of each load portion among the power supply voltage, one of the fixed voltages generated by the plurality of step-down circuits, and the ground voltage;
A control unit that controls the plurality of switches according to a level of the power supply voltage,
The control unit controls the plurality of switches to supply the power supply voltage and the ground voltage to both side terminals of all the load units when the power supply voltage is less than a predetermined first threshold value. Power supply.   The power supply apparatus according to claim 3, wherein the control unit changes a load unit that supplies the power supply voltage and the ground voltage in accordance with operating states of the plurality of load units. The plurality of load units are classified into a first load unit, a second load unit, and a third load unit,
The plurality of step-down circuits step down the power supply voltage to generate a first fixed voltage, and step down the power supply voltage to generate a second fixed voltage lower than the first fixed voltage. 2 step-down circuit,
When the level of the power supply voltage exceeds a predetermined second threshold, the control unit supplies the power supply voltage and the first fixed voltage to both side terminals of the first load unit, and the both side terminals of the second load unit. The plurality of switches are controlled to supply the first fixed voltage and the second fixed voltage, and the second fixed voltage and the ground voltage to both side terminals of the third load unit, respectively. Item 5. The power supply device according to Item 3 or 4. A step-down circuit that steps down a predetermined power supply voltage to generate a fixed voltage;
A first voltage control unit in which a fixed voltage generated by the step-down circuit is applied to a low potential side terminal;
A second voltage control unit that applies a fixed voltage generated by the step-down circuit to a high-potential side terminal;
The high potential side terminal of the first voltage control unit is connected to the low potential side terminal of the first load to which the power supply voltage is applied to the high potential side terminal,
The power supply apparatus, wherein the low potential side terminal of the second voltage control unit is connected to a high potential side terminal of a second load to which a ground voltage is applied to the low potential side terminal.