Power supply circuit, electronic device, and step-up control method

Abstract

To provide a power supply circuit, an electronic apparatus, and a step-up control method capable of performing more stable and efficient voltage step-up.SOLUTION: A power supply circuit (60) includes: an oscillation circuit (631) for performing an oscillation operation according to input of an input voltage (Vin) and outputting an oscillation signal; a plurality of changeover parts (610) for a Dickson type charge pump circuit; capacitors (621 to 624); a first signal generation part (632) for generating a first clock signal for changing voltage at one ends of the capacitors; a first voltage detection part (641) for detecting the input voltage; and a second signal generation part (633) for generating a second clock signal for causing changeover an operation for turning on / off of the changeover parts in synchronizing with the first clock signal by input of a battery voltage (Vbat) different from the input voltage.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power supply circuit, an electronic device, and a boost control method.

Background Art

[0002] Among electronic devices, there are those that boost an input voltage to charge a battery or supply it to some components. The boosting mechanism includes a charge pump circuit. In a typical configuration of a small and low-cost Dickson-type charge pump circuit, the other ends of capacitors, each of which has one end connected to the output ends of a plurality of MOSFETs connected in series and each receiving the input voltage at its gate, are alternately boosted and lowered every other one in response to a clock signal, thereby increasing the voltage by the width of each boost and lower operation.

[0003] This charge pump circuit includes loss factors such as a reduction in the actual voltage boost width. Therefore, various techniques have been devised to improve the boost efficiency, which is the ratio of the actual voltage boost width to the boost and lower width. Patent Document 1 discloses a technique for reducing the reduction in the efficiency of power increase due to the substrate effect by combining an enhancement type and a depletion type as FETs. In Patent Document 2, in order to suppress the fact that a section where adjacent FETs are actually turned on simultaneously occurs due to complementary boosting during operation at a high frequency and the charge transfer loss due to the through current becomes non-negligible, a technique is disclosed in which all FETs are temporarily turned off at the time of switching of the clock signal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Among electronic devices, there are those that boost the generated voltage of a generator, store electricity in a secondary battery, and supply power to an operating load. As generators included in portable electronic devices, for example, solar power generation is widely known. However, in such a generator, the generated voltage varies greatly depending on the situation of the electronic device. Since the charge pump circuit, which is a voltage boosting mechanism, has a large voltage drop when the input voltage is low, there is a problem that the conditions for appropriate voltage boosting are limited and stable voltage boosting cannot be achieved.

[0006] An object of the present invention is to provide a power supply circuit, an electronic device, and a voltage boosting control method that can more stably perform voltage boosting.

Means for Solving the Problems

[0007] To achieve the above object, the present invention provides an oscillation circuit that oscillates in response to an input of a first input voltage and outputs an oscillation signal; a plurality of switching units arranged in series, with the first input voltage input to the most upstream side and an output voltage output from the most downstream side, each of which performs an opening / closing operation according to the voltage difference across both ends; a capacitor having a first end connected between the plurality of switching units; a first signal generation unit that generates a first clock signal for raising and lowering the voltage of a second end opposite to the first end of the capacitor at a timing corresponding to the series arrangement position in response to the oscillation signal; a first detection unit that detects the first input voltage; a second signal generation unit that generates a second clock signal for causing a switching operation related to the opening / closing of the switching unit in synchronization with the first clock signal by an input of a second input voltage different from the first input voltage; and 、 When the first input voltage detected by the first detection unit is less than a first reference value, the second signal generation unit does not perform the switching operation of the switching unit this is a power supply circuit characterized by the above.

Effects of the Invention

[0008] According to the present invention, there is an effect that it becomes easier to perform step-up stably in the power supply circuit.

Brief Description of Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the functional configuration of an electronic device 1 having a power supply circuit 60 of the present embodiment.

[0011] The electronic device 1 is not particularly limited, but is a portable type that can be easily carried by a user. Examples include, but are not limited to, an electronic clock, a calculator, a measuring device, and the like. The electronic device 1 includes a CPU 10 (Central Processing Unit), a storage unit 20, a timing unit 30, a display unit 40, an operation reception unit 50, a power supply circuit 60, a power generation unit 70, a battery 80, and the like.

[0012] The CPU 10 performs arithmetic processing and comprehensively controls the operation of the electronic device 1. The CPU 10 may be single or a plurality of CPUs may operate independently. Alternatively, a plurality of CPUs 10 may perform parallel arithmetic processing.

[0013] The memory unit 20 has a volatile memory (RAM) and a non-volatile memory. The volatile memory provides a working memory space for the CPU 10 and stores temporary data. The non-volatile memory stores control programs and setting data related to the operation of the electronic device 1. The non-volatile memory is, for example, a flash memory, but is not limited thereto.

[0014] The timing unit 30 receives a clock signal of a predetermined frequency from an oscillation circuit (not shown), counts the number of input clock signals, and adds it to an initial value to count the current date and time. The timing unit 30 may be a dedicated counter or the like, or may be a timing process performed by the CPU 10.

[0015] The display unit 40 displays information based on the control of the CPU 10. The display unit 40 has, for example, a digital display screen such as a liquid crystal screen or an organic EL (Electro Luminescent) screen. The size, resolution, and displayed content of the display screen may be appropriately determined according to the use of the electronic device 1 and the like.

[0016] The operation reception unit 50 receives an operation from an external source such as a user, and outputs the received operation content to the CPU 10 as an input signal. The operation reception unit 50 is, for example, a touch panel located overlapping the digital display screen. In addition to or instead of this, the operation reception unit 50 may have various reception elements such as push button switches and slide switches. The CPU 10, the memory unit 20, the timing unit 30, the display unit 40, and the operation reception unit 50 constitute the operation units in the electronic device 1 of this embodiment.

[0017] The power supply circuit 60 outputs the input power to the CPU 10 at an appropriate voltage. The power supply circuit 60 will be described in detail later.

[0018] The power generation unit 70 performs a power generation operation and outputs generated power to the power supply circuit 60. The power generation unit 70 is not particularly limited, but performs solar power generation. The solar power generation here is not limited to sunlight, and power generation may be possible even with weaker indoor lighting or the like. The power generation unit 70 has a light receiving panel, converts incident light into voltage, and outputs it.

[0019] The battery 80 outputs power to the power supply circuit 60. Here, the battery 80 is a rechargeable secondary battery, and is supplied with power according to the operation of the power supply circuit 60 and charged by the operating voltage Vout. The type of the secondary battery is not particularly limited, and for example, it may be a lithium ion battery or a nickel metal hydride battery. Further, the battery 80 is a detachable general-purpose one and may not be provided in the electronic device 1.

[0020] Next, the power supply circuit 60 will be described. FIG. 2 is a diagram for explaining the circuit configuration of the power supply circuit 60.

[0021] The power supply circuit 60 boosts the input voltage Vin (first input voltage) input from the power generation unit 70 and outputs it as the operating voltage Vout (output voltage). The operating voltage Vout is output to the CPU 10 or the like and / or used for charging the battery 80. The boosting is performed by a charge pump circuit.

[0022] The charge pump circuit is based on a Dickson type circuit. As a configuration that the Dickson type charge pump circuit usually has, here, in addition to five switching elements 611 to 615 (diode structure), capacitors 621 to 625, an oscillation circuit 631, and a first signal generation unit 632, there are switching elements 616 to 620 (additional switches), a second signal generation unit 633, a first voltage detection unit 641 (first detection unit), a second voltage detection unit 642 (second detection unit), and the like.

[0023] Here, switching elements 611 and 616, switching elements 612 and 617, switching elements 613 and 618, switching elements 614 and 619, and switching elements 615 and 620 are each grouped in pairs and arranged in series (referred to as five switching units 610), and together with capacitors 621 to 624, a four-step boost is performed on the input voltage Vin input to the most upstream side. Capacitor 625 holds the boosted voltage and outputs a more stable voltage.

[0024] Switching elements 611 to 620 are all MOSFETs (FETs). Switching elements 611 to 615 are arranged in series between the input of the input voltage Vin and the output of the operating voltage Vout, and switching elements 616 to 620 (additional switches) are respectively located in parallel with switching elements 611 to 615.

[0025] For switching elements 611 to 615 (each switching unit 610), the source terminal (input side) and the gate terminal are directly connected on the input side (upstream side). As a result, switching elements 611 to 615 perform an opening and closing operation according to the voltage difference between the source (input side) and the drain (output side) (that is, both ends).

[0026] One end (first end) of each of capacitors 621 to 624 is connected between adjacent switching elements 611 to 615, and the other end (second end) opposite to the one end (first end) is connected to the first signal generation unit 632. One end of capacitor 625 is connected to the drain terminal, which is the output (downstream side) of switching element 615, and the other end is grounded.

[0027] Switching elements 616 to 620 are respectively connected in parallel with switching elements 611 to 615 across the source and drain of the switching elements 611 to 615, and the output signal of the second signal generation unit 633 is input to the gate.

[0028] The oscillation circuit 631 oscillates in response to the input of the input voltage Vin and outputs a signal (oscillation signal) having a predetermined frequency. The oscillation circuit 631 can perform an oscillation operation as long as the input voltage Vin is not extremely low (such as completely dark. A voltage lower than the reference voltage Vth1 described later).

[0029] The first signal generation unit 632 and the second signal generation unit 633 each output a clock signal that synchronizes with the oscillation frequency of the oscillation circuit 631 and alternately switches between two binary signals, that is, two levels of voltage, a high level and a low level. The low-level signal is not particularly limited, but may be a ground voltage. The first signal generation unit 632 operates by the input of the input voltage Vin, and the high-level signal in the clock signal (first clock signal) generated by the first signal generation unit 632 has the same voltage as the high-level signal output by the oscillation circuit 631, that is, is the same as or proportional to the input voltage Vin. The second signal generation unit 633 operates by the input of a battery voltage Vbat (second input voltage) different from the input voltage Vin, and the high-level signal in the clock signal (second clock signal) generated by the second signal generation unit 633 is the same as or proportional to the battery voltage Vbat. Since the battery voltage Vbat is at a level of the boosted voltage if it is charged to enable normal operation, it is larger than the input voltage Vin unless the discharge progresses significantly.

[0030] The second signal generation unit 633 can be switched so as to continuously output a low-level signal regardless of the input signal from the oscillation circuit 631. The second signal generation unit 633 may have a logic circuit (a dedicated hardware circuit) or a microcomputer that performs a switching determination and control operation.

[0031] The first voltage detection unit 641 detects and measures the input voltage Vin and outputs the measurement result to the second signal generation unit 633. The output may be data quantitatively indicating the input voltage Vin, or may be only the comparison result with the reference voltages Vth1 and Vth2 described later.

[0032] The second voltage detection unit 642 detects and measures the battery voltage Vbat and outputs the measurement result to the second signal generation unit 633. The output may be data quantitatively indicating the battery voltage Vbat, or may be only the comparison result with the reference voltage Vth3 described later. Further, the detection results of the first voltage detection unit 641 and / or the second voltage detection unit 642 may be output from the power supply circuit 60 to the CPU 10 or the like. This second voltage detection unit 642 may be used in combination with those used for normal charging management of the battery 80 and operation management based on the charging rate of the battery 80.

[0033] The first signal generation unit 632 alternately outputs a high-level signal and a low-level signal (at a timing corresponding to the series arrangement position) to the second terminals of the capacitors 621 to 624 one by one in series order, that is, to the second terminals of the capacitors 621 and 623 and the second terminals of the capacitors 622 and 624. As a result, the voltage at the first terminal of the capacitor where the high-level signal is output, that is, the connection side with the switching elements 611 to 615, periodically rises and falls by the voltage difference between the high-level signal and the low-level signal. As a result, the gate voltage of the switching element connected to the downstream side of the boosted capacitor rises with respect to the drain voltage of the switching element connected to the unboosted capacitor, and this switching element is turned on, and a current corresponding to the voltage difference flows between its source and drain, and the voltage of the unboosted capacitor rises. In this way, the drain voltage of each of the switching elements 611 to 615 rises by the amount of boost by the first signal generation unit 632, and finally the operating voltage Vout is obtained.

[0034] However, in reality, the boost width is reduced by the operating voltage (drain-source voltage drop) of each of the switching elements 611 to 615. Further, this operating voltage depends on the gate voltage, particularly in a voltage range close to the gate threshold voltage. When the generated power is small and the input voltage Vin is small, the operating voltage increases and the boost efficiency decreases.

[0035] That is, when turning on the switching element, it is more efficient to apply a sufficiently high voltage to the gate. In the electronic device 1 where the input voltage Vin from the power generation unit 70 is unstable, it is preferable to operate the switching element by using the battery 80 that outputs a voltage more stable than the input voltage Vin.

[0036] Therefore, in the electronic device 1, as described above, switching elements 616 to 620 (additional switches) are respectively located in parallel with the switching elements 611 to 615. By inputting the battery voltage Vbat to the gates of these switching elements 616 to 620, the battery voltage Vbat on the circuit is separated from the boost path (the path from the input of the input voltage Vin to the output of the operating voltage Vout). When the output of the second signal generation unit 633 is at a high level, the switching elements 616 to 620 are turned on in synchronization with the switching elements 611 to 615. Since the battery voltage Vbat is sufficiently higher than the input voltage Vin, the operating voltages of the switching elements 616 to 620 become lower than the operating voltages of the switching elements 611 to 615 respectively, and the current preferentially flows through the switching elements 616 to 620, improving the operating efficiency.

[0037] However, when the input voltage Vin is extremely low, sufficient power supply cannot be obtained even when the switching elements 616 to 620 are operated by the battery 80, and the power consumption of the battery 80 becomes larger. In such a case, based on the detection result of the first voltage detection unit 641, by stopping the input of the high-level signal to the gates of the switching elements 616 to 620 based on the battery voltage Vbat, power consumption can be reduced.

[0038] Further, when the battery 80 is largely discharged and it is difficult to output power at a sufficient battery voltage Vbat, even if the operation is performed by the battery voltage Vbat, the efficiency of the boost operation is not improved. Further, when the battery voltage Vbat extremely decreases, the switching elements 616 to 620 are not turned on in the first place. In such a case, the output operation of the high-level signal by the second signal generation unit 633 results in wasted power consumption. Therefore, the input of the high-level signal to the gates of the switching elements 616 to 620 based on the battery voltage Vbat is stopped and maintained at the low-level signal, and the switching elements 616 to 620 may be kept in the off state.

[0039] FIG. 3 is a matrix table showing an operation selection pattern of the switching element and a diagram showing a flowchart related to the operation selection.

[0040] As shown in FIG. 3(a), the switching elements 616 to 620 (additional switches) are operated by the second signal generation unit 633 when the input voltage Vin is not extremely low (high voltage range (H) to medium voltage range (M) equal to or higher than the reference voltage Vth1 (first reference value)) and the battery voltage Vbat is not too low (high voltage range (H) equal to or higher than the reference voltage Vth3 (third reference value)). In other cases, that is, when the input voltage Vin is less than the reference voltage Vth1 or the battery voltage Vbat is less than the reference voltage Vth3 (at least one of them is in the low voltage range (L)), the second signal generation unit 633 does not perform the switching operation and the output voltage is maintained at the low level (off state).

[0041] As shown in FIG. 3(b), in the power supply circuit 60, the second signal generation unit 633 performs a boost control process (the boost control method of the present embodiment) for switching the necessity of operation based on the output results of the first voltage detection unit 641 and the second voltage detection unit 642. The first signal generation unit 632 may continue to operate as long as the input voltage Vin at which the oscillation circuit 631 can operate is input.

[0042] When the boost control process is started, the second signal generation unit 633 (the configuration that performs the control operation) acquires measurement results from the first voltage detection unit 641 and the second voltage detection unit 642, and determines whether the input voltage Vin is equal to or higher than the reference voltage Vth1 and whether the battery voltage Vbat is equal to or higher than the reference voltage Vth3 (step S101; detection step). The reference voltage Vth1 may be determined as a voltage that is meaningless even if boosted for power supply. For example, the power consumption required for the operation of the switching elements 616 to 620 (additional switches) is larger, or the boost efficiency of the switching elements 616 to 620 (additional switches) cannot be sufficiently obtained compared to the switching elements 611 to 615.

[0043] If it is determined that the input voltage Vin is equal to or higher than the reference voltage Vth1 and the battery voltage Vbat is equal to or higher than the reference voltage Vth3 ( "YES" in step S101), the second signal generation unit 633 switches and operates the switching elements 616 to 620 according to the oscillation signal of the oscillation circuit 631 (step S102; signal generation step). Then, the process of the second signal generation unit 633 returns to step S101.

[0044] If it is determined that the input voltage Vin is less than the reference voltage Vth1 or the battery voltage Vbat is less than the reference voltage Vth3 ( "NO" in step S101), the second signal generation unit 633 stops the operation and continuously outputs a low-level signal to the switching elements 616 to 620 (additional switches) to turn off the switching elements 616 to 620 (additional switches) (step S103). Then, the process of the second signal generation unit 633 returns to step S101.

[0045] [Modification Example] FIG. 4 is a diagram for explaining Modification Example 1 of the boost control process. When the input voltage Vin is sufficiently high, the influence on the change in the operating voltage according to the gate voltage in the MOSFET is small, so it is not always necessary to operate by the battery voltage Vbat. That is, in this case (when the input voltage Vin is in the high voltage range H), as shown in Fig. 4(a), the operation of the switching elements 616 to 620 (additional switches) may be stopped.

[0046] In the first modification example of the boost control process shown in Fig. 4(b), the process of step S101 is changed to step S101a, and the process of step S111 is added. The processes of steps S102 and S103 are the same.

[0047] When the boost control process is started, the second signal generation unit 633 determines whether the input voltage Vin is equal to or higher than the reference voltage Vth2 (second reference value) that is the boundary between the medium voltage range and the high voltage range of the input voltage Vin, or whether the input voltage Vin is less than the reference voltage Vth1 (step S101a). When it is determined that the input voltage Vin is equal to or higher than the reference voltage Vth2 or less than the reference voltage Vth1 (\"YES\" in step S101a), the process of the second signal generation unit 633 proceeds to step S103.

[0048] When it is determined that the input voltage Vin is equal to or higher than the reference voltage Vth1 and less than the reference voltage Vth2 (\"NO\" in step S101a), the second signal generation unit 633 determines whether the battery voltage Vbat is equal to or higher than the reference voltage Vth3 (step S111). When it is determined that the battery voltage Vbat is equal to or higher than the reference voltage Vth3 (\"YES\" in step S111), the process of the second signal generation unit 633 proceeds to step S102. When it is determined that the battery voltage Vbat is less than the reference voltage Vth3 (\"NO\" in step S111), the process of the second signal generation unit 633 proceeds to step S103.

[0049] Fig. 5 is a diagram for explaining a second modification example of the boost control process. Even when the battery voltage Vbat is low, if the input voltage Vin is sufficiently high, the boosted operating voltage Vout can be output to each part such as the CPU 10, and the output destination may include the second signal generation unit 633. That is, as shown in FIG. 5(a), when the input voltage Vin is equal to or higher than the reference voltage Vth2 (high voltage range H), regardless of the level of the battery voltage Vbat, the second signal generation unit 633 may output a signal for operating the switching elements 616 to 620 (additional switches).

[0050] In the boost control process of this modification 2 shown in FIG. 5(b), step S101b is executed instead of step S101, and the process of step S111b is executed instead of step S111 shown in the first modification. The contents of the processes in steps S102 and S103 are the same as those in the above embodiment.

[0051] When the boost control process is started, the second signal generation unit 633 determines whether the input voltage Vin is equal to or higher than the reference voltage Vth2 (that is, whether it is in the high voltage range H) (step S101b). If it is determined that the input voltage Vin is equal to or higher than the reference voltage Vth2 ( "YES" in step S101b), the process of the second signal generation unit 633 proceeds to step S102.

[0052] If it is determined that the input voltage Vin is lower than the reference voltage Vth2 ( "NO" in step S101b), the second signal generation unit 633 determines whether the input voltage Vin is equal to or higher than the reference voltage Vth1 (that is, in the medium voltage range M) and whether the battery voltage Vbat is equal to or higher than the reference voltage Vth3 (step S111b). If it is determined that the input voltage Vin is equal to or higher than the reference voltage Vth1 and the battery voltage Vbat is equal to or higher than the reference voltage Vth3 ( "YES" in step S111b), the process of the second signal generation unit 633 proceeds to step S102. If it is determined that the input voltage Vin is lower than the reference voltage Vth1 (that is, in the low voltage range L) or the battery voltage Vbat is lower than the reference voltage Vth3 ( "NO" in step S111b), the process of the second signal generation unit 633 proceeds to step S103.

[0053] As described above, the power supply circuit 60 of the present embodiment includes an oscillation circuit 631 that oscillates in response to the input of the input voltage Vin and outputs an oscillation signal, a plurality of switching units 610 that are arranged in series, with the input voltage Vin input to the most upstream side and the operating voltage Vout output from the most downstream side, and each of which opens and closes in response to the voltage difference across both ends, capacitors 621 to 624 having a first end connected between the switching units 610, a first signal generation unit 632 that generates a clock signal for raising and lowering the voltage of the second end opposite to the first end of the capacitors 621 to 624 at a timing corresponding to the series arrangement position in response to the oscillation signal, a first voltage detection unit 641 that detects the input voltage Vin, and a second signal generation unit 633 that generates a clock signal for opening and closing the switching unit 610 in synchronization with the above clock signal in response to the input of a battery voltage Vbat different from the input voltage Vin. In this way, instead of operating the Dickson type charge pump circuit with the input voltage Vin itself, by operating the charge pump circuit using the battery voltage Vbat that is more stable and easier to obtain a high voltage, even when the input generated voltage is low and it is difficult to perform appropriate boosting with its own input voltage, stable boosting can be performed. Therefore, the power supply circuit 60 can easily perform boosting even when the input voltage is unstable.

[0054] Further, the power supply circuit 60 includes a plurality of capacitors 621 to 624, and the number of switching units 610 is one more than the number of capacitors 621 to 624. The capacitors 621 to 624 are positioned with a first end connected one by one between the switching units 610, and the voltage of the second end is alternately raised and lowered every other one in the series arrangement order by the first clock signal. Thereby, multi-stage voltage amplification is appropriately performed by the Dickson type charge pump circuit, and by appropriately switching the supply of the operating power of the switching unit 610 related to the multi-stage voltage amplification as described above, the power supply circuit 60 can boost to a desired voltage more efficiently.

[0055] Further, when the input voltage Vin detected by the first voltage detection unit 641 is less than the reference voltage Vth1, the second signal generation unit 633 does not perform the switching operation of the switching unit 610. When the switching unit 610 is operated by the battery voltage Vbat, the power of the battery 80 is consumed. Therefore, when the input voltage Vin is extremely low and sufficient boost cannot be expected, switching is performed so as not to use the battery 80, thereby reducing wasteful power consumption. As a result, in the power supply circuit 60, boosting can be performed more efficiently.

[0056] Further, when the input voltage Vin detected by the first voltage detection unit 641 is equal to or higher than the reference voltage Vth2 that is higher than the reference voltage Vth1, the second signal generation unit 633 may not perform the opening / closing operation of the switching unit 610. If the input voltage Vin is sufficiently high, there is no significant difference in the boost efficiency. Therefore, it is not necessary to operate the switching elements 616 to 620 using the battery 80. Even if the operating range of the switching elements 615 to 618 is limited in this way, the power supply circuit 60 can boost more efficiently than before.

[0057] Further, the switching unit 610 includes switching elements 611 to 615 having a diode structure that is turned on when the voltage on the input side is high, and switching elements 616 to 620 that are located in parallel with the switching elements 611 to 615 and perform an opening / closing operation in response to a second clock signal. In this way, in the switching unit 610, the switching elements are arranged in parallel, and the switching elements 616 to 620 operate only when necessary, so that the voltage drop caused by the switching elements 611 to 620 can be minimized and the boost efficiency can be increased. Also, the path from the battery voltage Vbat and the input voltage Vin to the operating voltage Vout can be easily separated.

[0058] Further, the diode structure is an FET in which the source terminal and the gate terminal on the input side are connected, and the switching element is an FET to which a second clock signal is input to the gate terminal. By having such an FET structure, the power supply circuit 60 can be easily manufactured by a semiconductor process.

[0059] Further, the power supply circuit 60 includes a second voltage detection unit 642 that detects the battery voltage Vbat. When the battery voltage Vbat detected by the second voltage detection unit 642 is less than the reference voltage Vth3, the second signal generation unit 633 may not perform the opening / closing operation of the switching unit 610. Thus, even if an attempt is made to operate in a situation where the battery voltage Vbat is low, rather than the switching elements 611 to 615, the boost efficiency deteriorates and it becomes meaningless, resulting in wasted power consumption. Therefore, when the charging rate of the battery 80 is low and the battery voltage Vbat is low, the switching elements 616 to 620 may be controlled not to operate. This makes it possible to more appropriately increase the boost efficiency and suppress unnecessary power consumption.

[0060] Also, the output destination of the operating voltage Vout includes the battery 80, and the battery voltage Vbat is the output of the battery 80. Thereby, even in a boost circuit where mainly unstable generated power such as photovoltaic power generation is input, by supplying power from the battery 80, which is a secondary battery charged through the boost circuit, it is possible to perform a boost operation in a state of high and stable boost efficiency regardless of short-term changes in the input voltage Vin.

[0061] Further, the electronic device 1 of the present embodiment includes the above-described power supply circuit 60, a CPU 10 as an operating unit that operates with the operating voltage Vout, a storage unit 20, a timing unit 30, a display unit 40, an operation reception unit 50, and the like. According to this electronic device 1, a sufficient voltage can be applied to the gate more stably than in the past, so that the boost efficiency can be increased, power consumption can be made more appropriate, and stable operation can be achieved.

[0062] Further, the electronic device 1 includes a power generation unit 70 that generates an input voltage Vin, and a battery 80 that is charged by an operating voltage Vout. In the electronic device 1 that generates power by itself using a solar panel or the like and operates while charging, it is difficult to obtain a stable power generation voltage. Therefore, by also using the operation based on the voltage of the charged battery 80 according to the situation, the operating voltage of the switching unit 610 can be appropriately reduced. As a result, the electronic device 1 can operate stably while more efficiently charging and discharging the battery 80.

[0063] Also, the boost control method of the present embodiment includes a detection step of detecting the input voltage Vin, and a signal generation step of generating a second clock signal that causes a switching operation related to the opening and closing of the switching unit 610 to be performed in synchronization with the first clock signal by input of a battery voltage Vbat different from the input voltage Vin. In this way, by operating the charge pump circuit with the battery voltage Vbat that is more stable and higher than the input voltage Vin, the voltage drop is reduced and the boost efficiency is increased. Therefore, even when the input power generation voltage is low and it is difficult to perform appropriate boosting with its own input voltage, boosting can be performed more stably. Thus, the power supply circuit 60 can easily perform boosting even when the input voltage is unstable.

[0064] Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the switching elements 616 to 620 are located in parallel with the switching elements 611 to 615, and the configuration in which the presence or absence of the opening and closing operations of the switching elements 616 to 620 is switched has been described. However, the present invention is not limited to this. A configuration may be adopted in which an output signal of a second signal generation unit 633 corresponding to the battery voltage Vbat or the input voltage Vin is selectively input to the gates of the switching elements 611 to 615. In this case, in order not to short-circuit the input side and the battery 80 side, an element related to the input switching may be added.

[0065] Although the description was made on the assumption that the switching elements 611 to 615 continue to operate regardless of the switching operation control of the second signal generation unit 633, a circuit configuration may be adopted in which the switching elements 611 to 615 are turned off while the switching elements 616 to 620 are performing a switching operation.

[0066] In the above embodiment, power generation by a solar panel was described as an example, but the present invention is not limited to this. Any power generation unit 70 that can be provided in the electronic device 1 may be used. Further, the power generation unit 70 may not be provided in the electronic device 1, but may be an external device or the like that can be attached to the electronic device 1. Further, instead of the power generation unit, an external battery may be used.

[0067] In the above embodiment, the battery 80 was described as a secondary battery, but a dry battery (primary battery) may be used.

[0068] In the above embodiment, the switching elements 616 to 620 were described as MOSFETs. However, the present invention is not limited to this as long as the voltage drop is small and the switching of energization can be performed with low power consumption. Further, the switching elements 611 to 615 may also have other diode structures in which the opening and closing (presence or absence of energization) is automatically determined according to the difference between the input and output voltages, for example, various diodes and transistors.

[0069] Further, it is not necessary to consider the battery voltage Vbat for the boost control. In this case, the second signal generation unit 633 does not need to acquire the voltage measurement result from the second voltage detection unit 642, and the second voltage detection unit 642 does not need to be able to output the comparison result between the battery voltage Vbat and the reference voltage Vth3.

[0070] Also, it is not necessary to consider the input voltage Vin for the boost control. In this case, the switching elements 616 to 620 are always operated by the battery voltage Vbat regardless of the magnitude of the input voltage Vin. Therefore, the power supply circuit 60 may not have the switching elements 611 to 615. However, if the battery 80 discharges significantly, such as when left in a dark place for a long time, the battery 80 cannot operate the switching elements 616 to 620 and it becomes difficult to recharge the battery 80. Thus, the power supply circuit 60 used in an electronic device or the like where such a situation can be assumed may have the switching elements 611 to 615 to perform a boost and charging operation with the input voltage when the battery 80 cannot operate the switching elements 616 to 620.

[0071] Also, in the above embodiment, it has been described that the logic circuit or the microcomputer of the second signal generation unit 633 performs switching control related to the output of the second clock signal. However, it is not limited to this as long as the control operation is possible in a situation where at least a minimum input voltage Vin is input even when the battery voltage Vbat is very low. Other control units such as other microcomputers and CPUs may make a judgment and output a switching control signal to the second signal generation unit 633. In addition, the specific configurations, processing operation details, procedures, etc. shown in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

[0072] Although some embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and its equivalent scope. The invention described in the claims first attached to the application of this filing is appended below. The claim numbers described in the appendix are as in the claims first attached to the application of this filing.

[0073] [Appendix] [Claim 1] An oscillation circuit that oscillates in response to the input of a first input voltage and outputs an oscillation signal, Arranged in series, with the first input voltage input to the most upstream side and the output voltage output from the most downstream side, a plurality of switching parts that perform opening and closing operations according to the voltage difference across each of them, A capacitor having a first end connected between the plurality of switching parts, A first signal generation unit that generates a first clock signal for raising and lowering the voltage of the second end opposite to the first end of the capacitor according to the oscillation signal at a timing corresponding to the serial arrangement position, A first detection unit that detects the first input voltage, A second signal generation unit that generates a second clock signal for causing a switching operation related to the opening and closing of the switching part in synchronization with the first clock signal by the input of a second input voltage different from the first input voltage, A power supply circuit characterized by comprising the above. <Claim 2> Comprising a plurality of the capacitors, The number of the plurality of switching parts is one more than the number of the plurality of capacitors, The plurality of capacitors, Have the first ends connected one by one between the plurality of switching parts and are positioned, The voltage of the second end is alternately raised and lowered every other one in the serial arrangement order by the first clock signal The power supply circuit according to claim 1, characterized by the above. <Claim 3> The second signal generation unit does not perform the switching operation of the switching part when the first input voltage detected by the first detection unit is less than a first reference value. The power supply circuit according to claim 1 or 2, characterized by the above. <Claim 4> The second signal generation unit does not perform the switching operation of the switching part when the first input voltage detected by the first detection unit is greater than or equal to a second reference value greater than the first reference value. The power supply circuit according to claim 3, characterized by the above. <Claim 5> The switching part, Has a diode structure that is turned on when the voltage on the input side is high, A switching element that is located in parallel with the diode structure and that opens and closes in response to the second clock signal; The power supply circuit according to any one of claims 1 to 4, characterized by having . <Claim 6> The diode structure is an FET having its input side and gate terminal connected; The switching element is an FET having the second clock signal input to its gate terminal The power supply circuit according to claim 5, characterized by the above. <Claim 7> A second detection unit for detecting the second input voltage is provided; When the second input voltage detected by the second detection unit is less than a third reference value, the second signal generation unit does not perform the switching operation of the switching unit The power supply circuit according to any one of claims 1 to 6, characterized by the above. <Claim 8> A secondary battery is included at the output destination of the output voltage, and the second input voltage is the output voltage of the secondary battery. The power supply circuit according to any one of claims 1 to 7, characterized by the above. <Claim 9> The power supply circuit according to any one of claims 1 to 8, and An operating unit that operates with the output voltage, An electronic device characterized by including the above. <Claim 10> A power generation unit that generates the first input voltage, A secondary battery that is charged with the output voltage, The electronic device according to claim 9, characterized by including the above. <Claim 11> An oscillation circuit that oscillates in response to the input of a first input voltage and outputs an oscillation signal, a plurality of switching units that are arranged in series, with the first input voltage input to the most upstream side and an output voltage output from the most downstream side, and each of which performs an opening / closing operation in response to the voltage difference across both ends, a capacitor having a first end connected between the plurality of switching units, and a first signal generation unit that generates a first clock signal for raising and lowering the voltage of a second end opposite to the first end of the capacitor at a timing corresponding to the series arrangement position in response to the oscillation signal. A boost control method in a power supply circuit comprising: A detection step of detecting the first input voltage; A signal generation step of generating a second clock signal for causing a switching operation related to the opening / closing of the switching unit in synchronization with the first clock signal by the input of a second input voltage different from the first input voltage; A boost control method characterized by including the above.

Explanation of Reference Numerals

[0074] 1 Electronic device 10 CPU 20 Storage unit 30 Timing unit 40 Display unit 50 Operation reception unit 60 Power supply circuit 61 Charge pump circuit 610 Switching unit 611~620 Switching elements 621~625 Capacitors 631 Oscillation circuit 632 First signal generation unit 633 Second signal generation unit 641 First voltage detection unit 642 Second voltage detection unit 70 Power generation unit 80 Battery Vbat Battery voltage Vin Input voltage Vout Operating voltage Vth1~Vth3 Reference voltage

Claims

1. An oscillation circuit that oscillates in response to the input of a first input voltage and outputs an oscillation signal; A plurality of switching units arranged in series, with the first input voltage input to the uppermost upstream side and an output voltage output from the lowermost downstream side, each of which operates to open and close in response to the voltage difference across both ends; A capacitor having a first end connected between the plurality of switching units; A first signal generation unit that generates a first clock signal for raising and lowering the voltage of a second end opposite to the first end of the capacitor at a timing corresponding to the series arrangement position in response to the oscillation signal; A first detection unit that detects the first input voltage; A second signal generation unit that generates a second clock signal for causing a switching operation related to the opening and closing of the switching unit in synchronization with the first clock signal in response to the input of a second input voltage different from the first input voltage; Comprising: When the first input voltage detected by the first detection unit is less than a first reference value, the second signal generation unit does not perform the switching operation of the switching unit A power supply circuit characterized by this.

2. Comprising a plurality of the capacitors; The number of the plurality of switching units is one more than the number of the plurality of capacitors; The plurality of capacitors are: Positioned with the first end connected one by one between the plurality of switching units, The voltage of the second end is alternately raised and lowered every other one in the series arrangement order by the first clock signal The power supply circuit according to claim 1, characterized by this.

3. When the first input voltage detected by the first detection unit is greater than or equal to a second reference value greater than the first reference value, the second signal generation unit does not perform the switching operation of the switching unit. The power supply circuit according to claim 1, characterized by this.

4. The switching unit: A diode structure that is turned on when the voltage on the input side is high; A switching element that is positioned in parallel with the diode structure and operates to open and close in response to the second clock signal; The power supply circuit according to any one of claims 1 to 3, characterized by having this.

5. The diode structure is an FET with the input side and the gate terminal connected; The switching element is an FET with the second clock signal input to the gate terminal The power supply circuit according to claim 4, characterized by this.

6. Comprising a second detection unit that detects the second input voltage; When the second input voltage detected by the second detection unit is less than a third reference value, the second signal generation unit does not perform the switching operation of the switching unit The power supply circuit according to any one of claims 1 to 5, characterized in that...

7. An oscillation circuit that oscillates in response to the input of a first input voltage and outputs an oscillation signal, A plurality of switching units arranged in series, with the first input voltage input to the most upstream side and an output voltage output from the most downstream side, each of which operates to open and close in response to the voltage difference across both ends, A capacitor having a first end connected between the plurality of switching units, A first signal generation unit that generates a first clock signal for raising and lowering the voltage of a second end opposite to the first end of the capacitor in accordance with the oscillation signal at a timing corresponding to the series arrangement position, A first detection unit that detects the first input voltage, A second signal generation unit that generates a second clock signal for causing a switching operation related to the opening and closing of the switching unit in synchronization with the first clock signal in response to the input of a second input voltage different from the first input voltage, Comprising: A secondary battery is included at the output destination of the output voltage, and the second input voltage is the output voltage of the secondary battery. The power supply circuit is characterized in that.

8. The power supply circuit according to any one of claims 1 to 7, An operation unit that operates with the output voltage, An electronic device characterized by comprising:

9. A power generation unit that generates the first input voltage, A secondary battery that is charged by the output voltage, The electronic device according to claim 8, characterized by comprising:

10. In a boost control method for a power supply circuit comprising an oscillation circuit that oscillates in response to the input of a first input voltage and outputs an oscillation signal, a plurality of switching units arranged in series with the first input voltage input to the most upstream side and an output voltage output from the most downstream side, each of which operates to open and close in response to the voltage difference across both ends, and a capacitor having a first end connected between the plurality of switching units, and a first signal generation unit that generates a first clock signal for raising and lowering the voltage of a second end opposite to the first end of the capacitor in accordance with the oscillation signal at a timing corresponding to the series arrangement position, A detection step of detecting the first input voltage, A signal generation step of generating a second clock signal for causing a switching operation related to the opening and closing of the switching unit in synchronization with the first clock signal in response to the input of a second input voltage different from the first input voltage, Including: The signal generation step does not perform the switching operation of the switching unit when the first input voltage detected in the detection step is less than a first reference value. The boost control method is characterized in that.

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