Resonant switched capacitor converter, its controller circuit, and electronic device using the same

Abstract

To provide a resonance switched capacitor converter with an overcurrent protection function.SOLUTION: A controller circuit 200 of a resonance switched capacitor converter 100 comprises: an oscillator 150; a drive circuit 120; and an overcurrent protection circuit 160. The oscillator 150 generates a clock signal CLK. The drive circuit 120 drives a plurality of switches SW1 to SWm constituting a switch circuit 110 of the resonance switched capacitor converter in response to the clock signal CLK. The overcurrent protection circuit 160 varies a frequency of the clock signal CLK in a direction separating away from a resonance frequency ω0 when an overcurrent state of the resonance switched capacitor converter 100 is detected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to resonant switched capacitor converters. [Background technology]

[0002] DC / DC converters and charge pumps are used to generate voltages higher or lower than the power supply voltage. DC / DC converters that use inductors as energy storage elements can control the output voltage, but they have the problem of reduced efficiency due to switching operations.

[0003] In applications that require high efficiency, switched capacitor converters (charge pumps) are used, which do not require inductors as energy storage elements. One type of switched capacitor converter known is one that adds a resonant inductor in series with the flying capacitor to achieve resonant operation (called a resonant switched capacitor converter). A resonant switched capacitor converter enables zero-current switching (soft switching), enabling highly efficient operation.

[0004] One type of resonant switched capacitor converter is known as a switched tank converter, which is a configuration in which an inductor is added to a Dickson-type charge pump. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 9,917,517 Summary of the Invention [Problem to be solved by the invention]

[0006] It is in this context that the present disclosure has been made, and one of its exemplary purposes is to provide a resonant switched capacitor converter with overcurrent protection. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to a controller circuit for a resonant switched capacitor converter, the controller circuit including an oscillator that generates a clock signal, a drive circuit that drives a plurality of switches constituting a switch circuit of the resonant switched capacitor converter in response to the clock signal, and an overcurrent protection circuit that changes the frequency of the clock signal away from the resonant frequency when an overcurrent state of the resonant switched capacitor converter is detected.

[0008] Another aspect of the present disclosure is a method of controlling a resonant switched capacitor converter, comprising the steps of sensing an output current of the resonant switched capacitor converter and varying a switching frequency of the resonant switched capacitor converter away from a resonant frequency when the output current exceeds a predetermined threshold.

[0009] Any combination of the above components, or mutual substitution of components or expressions between methods, devices, systems, etc. are also valid aspects of the present invention. [Effects of the Invention]

[0010] According to certain aspects of the present disclosure, overcurrent protection can be achieved. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a circuit diagram of a resonant switched capacitor converter according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the relationship between the gain and the switching frequency ω of the resonant switched capacitor converter. [Figure 3]FIG. 3 is a circuit diagram of the resonant switched capacitor converter according to the first embodiment. [Figure 4] FIG. 4 is a time chart illustrating the operation of the resonant switched capacitor converter. [Figure 5] FIG. 5 is a circuit diagram of the controller IC according to the first embodiment. [Figure 6] FIG. 6 is a circuit diagram of a controller IC according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating the operation of the frequency controller of FIG. [Figure 8] FIG. 8 is a circuit diagram of a resonant switched capacitor converter according to a third embodiment. [Figure 9] FIG. 9 is a diagram illustrating the operation of the resonant switched capacitor converter of FIG. [Figure 10] FIG. 10 is an operational waveform diagram of the resonant switched capacitor converter of FIG. [Figure 11] FIG. 11 is a circuit diagram of a resonant switched capacitor converter according to a fourth embodiment. [Figure 12] FIG. 12 is a circuit diagram of a resonant switched capacitor converter according to a fifth embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of an electronic device including a resonant switched capacitor converter. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0013] In one embodiment, a controller circuit for a resonant switched capacitor converter includes an oscillator that generates a clock signal, a drive circuit that drives a plurality of switches that constitute a switch circuit of the resonant switched capacitor converter in response to the clock signal, and an overcurrent protection circuit that changes the frequency of the clock signal away from the resonant frequency when an overcurrent condition of the resonant switched capacitor converter is detected.

[0014] According to this configuration, by moving the switching frequency away from the resonant frequency, the gain of the resonant switched capacitor converter can be reduced, the output voltage can be reduced, and the output current can be reduced.

[0015] In one embodiment, the controller circuit may further comprise a frequency controller that controls the oscillation frequency of the oscillator in response to the output voltage of the resonant switched capacitor converter under normal conditions.

[0016] With this configuration, by optimizing the switching frequency according to the output voltage of the resonant switched capacitor converter, the resonant switched capacitor converter can be operated with soft switching even when the resonant frequency varies, thereby improving efficiency. Furthermore, in an overcurrent state, frequency control by the frequency controller can be disabled to move the switching frequency away from the resonant frequency.

[0017] In one embodiment, the frequency controller may control the oscillation frequency of the oscillator so that the output voltage of the resonant switched capacitor converter approaches a maximum value under normal conditions, thereby achieving zero current switching (ZCS).

[0018] In one embodiment, the frequency controller may change the oscillation frequency of the oscillator in the first direction in the next frequency control cycle when changing the oscillation frequency of the oscillator in a first direction results in an increase in the output voltage of the resonant switched capacitor converter, and may change the oscillation frequency of the oscillator in a second direction opposite to the first direction in the next frequency control cycle when the output voltage of the resonant switched capacitor converter decreases.

[0019] In one embodiment, the frequency controller may vary the oscillation frequency of the oscillator in a region where the oscillation frequency of the oscillator is higher than the resonant frequency of the resonant switched capacitor converter under normal conditions, thereby improving efficiency through zero voltage switching (ZVS).

[0020] In one embodiment, the frequency controller may vary the oscillation frequency of the oscillator so that the output voltage of the resonant switched capacitor converter approaches a target voltage under normal conditions, thereby allowing the output voltage to be set to any voltage level.

[0021] In one embodiment, the controller circuit may be monolithically integrated on a single semiconductor substrate. "Monolithic integration" includes cases where all of the circuit components are formed on a semiconductor substrate, or where the main circuit components are monolithically integrated, and some resistors, capacitors, etc., for adjusting circuit constants may be provided outside the semiconductor substrate. By integrating the circuit on a single chip, the circuit area can be reduced and the characteristics of the circuit elements can be maintained uniformly.

[0022] (Embodiment) The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0023] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the function or effect achieved by their connection.

[0024] Similarly, "a state in which component C is provided between component A and component B" includes not only cases in which components A and C, or components B and C, are directly connected, but also cases in which they are indirectly connected via other components that do not substantially affect the electrical connection state between them or impair the functions or effects achieved by their combination.

[0025] Furthermore, "signal A (voltage, current) corresponds to signal B (voltage, current)" means that signal A has a correlation with signal B, and specifically means (i) when signal A is signal B, (ii) when signal A is proportional to signal B, (iii) when signal A is obtained by level-shifting signal B, (iv) when signal A is obtained by amplifying signal B, (v) when signal A is obtained by inverting signal B, (vi) or any combination thereof. Those skilled in the art will understand that the scope of "corresponding to" is determined depending on the type and application of signals A and B.

[0026] The vertical and horizontal axes of the waveform diagrams and time charts referred to in this specification have been appropriately enlarged or reduced to facilitate understanding, and the waveforms shown have been simplified, exaggerated, or emphasized to facilitate understanding.

[0027] (Embodiment) 1 is a circuit diagram of a resonant switched capacitor converter 100 according to an embodiment. The resonant switched capacitor converter 100 includes at least one capacitor C1 to Cn, an inductor L, a switch circuit 110, a drive circuit 120, an oscillator 150, and an overcurrent protection circuit 160. Of these, at least the drive circuit 120, the oscillator 150, and the overcurrent protection circuit 160 are integrated into a single semiconductor chip (hereinafter referred to as a controller IC (Integrated Circuit)) 200. The switch circuit 110 may also be integrated into the controller IC 200.

[0028] The topology of the resonant switched capacitor converter 100 is not particularly limited, and the gain of the resonant switched capacitor converter 100, that is, the voltage division ratio or voltage step-up ratio, is also not particularly limited.

[0029] The inductor L1 is connected in series with one of the capacitors C1 to Cn (a flying capacitor) to form an LC resonant circuit. Note that a plurality of inductors may be provided corresponding to a plurality of flying capacitors.

[0030] The switch circuit 110 includes an input node IN, an output node OUT, a ground node GND, and a plurality of switches SW. The input node IN is connected to an input voltage V IN is supplied to the output node OUT, and the output voltage V of the resonant switched capacitor converter 100 is supplied to the output node OUT. OUT The ground node GND is grounded.

[0031] The oscillator 150 generates a clock signal CLK. The resonant switched capacitor converter 100 switches in synchronization with this clock signal CLK. In other words, the switching frequency of the resonant switched capacitor converter 100 is based on the frequency of the clock signal CLK (the oscillation frequency of the oscillator 150). For example, the oscillation frequency of the oscillator 150 may be fixed at or near the resonant frequency ω0 of the resonant switched capacitor converter 100. Alternatively, as will be described later, the output voltage V OUT The oscillation frequency of the oscillator 150 may be feedback-controlled in accordance with the above.

[0032] The drive circuit 120 drives the plurality of switches SW1 to SWm that constitute the switch circuit 110 in synchronization with a clock signal CLK. The drive circuit 120 includes drivers Dr1 to Drm that correspond to the plurality of switches SW1 to SWm.

[0033] The current sense pin CS of the controller IC200 detects the output current I of the resonant switched capacitor converter 100. OUT For example, a current detection signal IS indicating an output current I OUT The sense resistor R CS and input the voltage (voltage drop) between both ends of the resistor to the current detection pin CS as the current detection signal IS.

[0034] The overcurrent protection circuit 160 detects an overcurrent state of the resonant switched capacitor converter 100 based on the current detection signal IS. For example, the overcurrent protection circuit 160 may determine that an overcurrent state has occurred when the current detection signal IS exceeds a predetermined threshold. When the overcurrent protection circuit 160 detects an overcurrent state, it changes the frequency of the clock signal CLK generated by the oscillator 150 in a direction away from the resonant frequency.

[0035] The above is the configuration of the resonant switched capacitor converter 100. Next, the operation will be described.

[0036] 2 is a diagram showing the relationship between the gain and switching frequency ω of the resonant switched capacitor converter 100. Here, a 1 / 2 switched capacitor converter will be described as an example. The characteristics of the switched capacitor converter are expressed by the following equation.

number

[0037] ω0 is the resonant frequency, and when the switching frequency ω matches the resonant frequency ω0, the gain G reaches its maximum value of 1 / 2, and decreases as the switching frequency ω deviates from this value.

[0038] R represents the impedance of the load of the resonant switched capacitor converter 100. L is the Q factor of the circuit and Z0 is the characteristic impedance.

[0039] When the load is heavy (when R becomes small), the Q value becomes large, and the decrease in gain becomes large when the switching frequency ω deviates from the resonance frequency ω0.

[0040] For example, in a normal state (non-overcurrent state), the oscillation frequency of the oscillator 150 is set within the hatched region (NORMAL) near the resonant frequency ω0, and the gain of the resonant switched capacitor converter 100 is close to 1 / 2. At this time, the resonant switched capacitor converter 100 operates at a gain of approximately 1 / 2 when the input voltage V IN Output voltage V OUT Generate.

[0041] When the overcurrent protection circuit 160 detects an overcurrent state, the oscillation frequency of the oscillator 150 is changed in a direction away from the resonant frequency ω0. In the example of FIG. 2, the resonant frequency ω0 is increased to the region marked OCP. This allows the gain of the oscillator 150 to be reduced from 1 / 2. This reduces the output voltage V of the resonant switched capacitor converter 100. OUT and the output current I OUTIn an overcurrent state, the switching frequency may be changed to a frequency lower than the resonant frequency ω0.

[0042] The present disclosure covers various devices and methods that can be understood as the block diagram or circuit diagram of Figure 1 or derived from the above description, and is not limited to a specific configuration. Below, more specific configuration examples and examples will be described not to narrow the scope of the present disclosure, but to aid in understanding and clarify the essence and operation of the present disclosure and the present invention.

[0043] Example 1 3 is a circuit diagram of a resonant switched capacitor converter 100A according to the first embodiment. The resonant switched capacitor converter 100A has a gain of 1 / 2, and the input voltage V IN is stepped down by half and the output voltage V OUT =V IN The resonant switched capacitor converter 100A includes two capacitors C1 and C2, one inductor L1, and a controller IC 200A. The switch circuit 110A includes switches SW1 to SW4. This resonant switched capacitor converter 100A has a configuration in which an inductor is added in series with the flying capacitor of the 1 / 2 charge pump.

[0044] The switches SW1 to SW4 are driven by a controller IC 200A. In this embodiment, the switches SW1 to SW4 are N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). A drive signal for the ith switch SWi is i It is written as S i When is H (high), the switch SWi is on, and S i When is L (low), the switch SWi is off.

[0045] The resonant switched capacitor converter 100A can be switched between a first state φ1 and a second state φ2. In the first state φ1, the first switch SW1 and the third switch SW3 are on, and the second switch SW2 and the fourth switch SW4 are off. At this time, an LC resonant circuit 106 including a capacitor C1 and an inductor L1 is connected in series with a capacitor C2, and an input voltage V IN When C1=C2, the voltage across each capacitor C1 and C2 is V IN It is charged at / 2.

[0046] In the second state φ2, the first switch SW1 and the third switch SW3 are off, and the second switch SW2 and the fourth switch SW4 are on. At this time, the LC resonant circuit 106 including the capacitor C1 and the inductor L1 is connected in parallel with the capacitor C2, and V OUT =V IN / 2 occurs.

[0047] 4 is a time chart illustrating the operation of the resonant switched capacitor converter 100A. In FIG. 4, the drive signals S1 to S4 and the resonant current I flowing through the LC resonant circuit 106 are shown. RES , input current I in , output current I OUT is shown.

[0048] Resonant current I RES When the frequency (resonant frequency) of the inverter and the switching frequency match, the inverter enters a zero current switching (soft switching) state, enabling highly efficient operation. SW is the switching period, which is the period of the clock CLK generated in the controller IC 200A, and represents the reciprocal of the switching frequency.

[0049] Next, the configuration of the controller IC 200A will be described.

[0050] 5 is a circuit diagram of a controller IC 200A according to the first embodiment. The controller IC 200A includes a drive circuit 120A, a frequency controller 130A, and an overcurrent protection circuit 160. The drive circuit 120A includes four drivers Dr1 to Dr4 corresponding to four switches SW1 to SW4. The drivers Dr1 and Dr3 operate in phase with the clock CLK, and the drivers Dr2 and Dr4 operate in anti-phase with the clock CLK.

[0051] The frequency controller 130A includes a variable frequency oscillator 132 and a frequency adjustment unit 134. The variable frequency oscillator 132 corresponds to the oscillator 150 in FIG. 1. In a normal state, the frequency adjustment unit 134 adjusts the feedback voltage V FB (Output voltage V OUT ) and adaptively controls the frequency of the variable frequency oscillator 132.

[0052] Specifically, the frequency adjuster 134 adjusts the output voltage V OUT The frequency of the variable frequency oscillator 132 is controlled in each frequency control cycle j so that the feedback voltage V approaches its maximum value. FB The current value of V FBj and the feedback voltage V FB Past values ​​of V FB(j-1) The frequency adjuster 134 is configured to be able to compare the feedback voltage V FB Past value of V FBj-1 The circuit includes a storage unit 136 such as a sample-and-hold circuit or memory for storing the signal, and a comparison circuit 138.

[0053] The frequency adjuster 134 changes the switching frequency, i.e., the frequency of the variable frequency oscillator 132, in a first direction (for example, an upward direction) in a certain frequency control cycle j. The resulting feedback voltage V FBj and the past feedback voltage V FBj-1 is compared by the comparator circuit 138. As a result of the comparison, the output voltage V OUT (Feedback voltage V FB) increases, the frequency of the variable frequency oscillator 132 is changed in the first direction (increasing direction) in the next frequency control cycle j+1. OUT (Feedback voltage V FB ) decreases, the frequency of the variable frequency oscillator 132 is changed in a second direction (downward direction) opposite to the first direction in the next frequency control cycle j+1. FBj is the past value V in the next frequency control cycle j+1 FBj This becomes:

[0054] The frequency adjuster 134 repeats this frequency control cycle to adjust the output voltage V OUT As can be seen in Figure 2, the output voltage V OUT When takes the maximum value, the switching frequency ω and the resonant frequency ω0 coincide, enabling zero current switching and improving efficiency.

[0055] When the overcurrent protection circuit 160 asserts the overcurrent detection signal OCP, the operation of the frequency adjuster 134 stops, and the frequency of the variable frequency oscillator 132 is adjusted to a predetermined frequency ω 0 away from the resonant frequency ω 0 . OCP This allows overcurrent protection to be applied.

[0056] Example 2 6 is a circuit diagram of a controller IC 200B according to Example 2. The controller IC 200B can be used in the resonant switched capacitor converter 100A of FIG. 3 as a substitute for the controller IC 200A.

[0057] The controller IC 200B includes a drive circuit 120B, a frequency controller 130B, and an overcurrent protection circuit 160. The configuration of the drive circuit 120B is similar to that of the drive circuit 120A in FIG.

[0058] The frequency controller 130B includes a variable frequency oscillator 132 and a feedback circuit 140.

[0059] The variable frequency oscillator 132 is a VCO (Voltage Controlled Oscillator) or a DCO (Digital Controlled Oscillator), and is controlled by a control signal S CTRL The variable frequency oscillator 132 oscillates at a frequency according to the signal level of the input signal. The variable frequency oscillator 132 corresponds to the oscillator 150 in FIG.

[0060] The feedback circuit 140 receives the output voltage V OUT Target Level V OUT(REF) The reference voltage V REF is input. Output voltage V OUT The feedback voltage V FB If the output voltage V OUT Target Level V OUT(REF) is the reference voltage V REF This becomes:

[0061] In a normal state, the feedback circuit 140 controls the frequency of the variable frequency oscillator 132 within the range where ω>ω0. Since the resonant switched capacitor converter 100A operates within the range where ω>ω0, its gain operates in a region smaller than 1 / 2, and the output voltage V OUT Target Level V OUT(REF) is V IN It is set lower than / 2.

[0062] The feedback circuit 140 generates a feedback voltage V FB and the reference voltage V REF The frequency of the variable frequency oscillator 132 is controlled so that the error approaches zero. The feedback circuit 140 can be configured as an analog circuit or a digital circuit. For example, the feedback circuit 140 controls the feedback voltage V FB and the reference voltage V REF It includes an error amplifier that amplifies the error of the control signal S CTRLto the variable frequency oscillator 132. Alternatively, the feedback circuit 140 may be configured as a digital circuit including a PI (proportional integral) controller or a PID (proportional integral derivative) controller.

[0063] 7 is a diagram illustrating the operation of the frequency controller 130B of FIG. 6. The operating range of the resonant switched capacitor converter 100A is limited to the range ω>ω0, and within this range, the output voltage V OUT Target Level V OUT(REF) is determined.

[0064] As a result of the feedback control of the frequency controller 130B, the frequency of the variable frequency oscillator 132, i.e., the switching frequency ω of the resonant switched capacitor converter 100A, is V OUT =V OUT(REF) The optimum frequency ω OPT is stabilized to

[0065] When an overcurrent state is detected by the overcurrent protection circuit 160, the feedback control by the feedback circuit 140 is stopped, and the frequency of the variable frequency oscillator 132 is set to a predetermined frequency ω OCP This allows overcurrent protection to be applied.

[0066] The above is the operation of the controller IC 200B. In the first embodiment, zero-current switching is realized by operating at ω=ω0, whereas in the second embodiment, zero-voltage switching is possible by operating at ω>ω0, thereby realizing highly efficient operation.

[0067] In Example 1, the output voltage V OUT is the input voltage V IN Since the input voltage V IN When the voltage fluctuates, the output voltage V OUT On the other hand, according to the second embodiment, the input voltage V IN Even if the output voltage V OUT is the reference voltage VREF The output voltage can be stabilized at a target level determined according to the

[0068] Example 3 8 is a circuit diagram of a resonant switched capacitor converter 100C according to a third embodiment. The resonant switched capacitor converter 100C is a switched tank converter having a gain of 1 / 4. The input voltage V IN is stepped down to 1 / 4 and the output voltage V OUT =V IN Generates / 4.

[0069] The resonant switched capacitor converter 100C includes three capacitors C1 to C3, two inductors L1 and L3, and a controller IC 200C. The switch circuit 110C includes switches SW1 to SW10. The resonant switched capacitor converter 100C is a switched tank converter in which inductors L1 and L3 are added to a Dickson charge pump.

[0070] The first switch SW1 to the fourth switch SW4 are N-channel MOSFETs, and are connected in series between the input terminal IN and the output terminal OUT.

[0071] The pair of the fifth switch SW5 and the sixth switch SW6, the pair of the seventh switch SW7 and the eighth switch SW8, and the pair of the ninth switch SW9 and the tenth switch SW10 configure inverters INV1 to INV3, respectively.

[0072] The switches SW1 to SW10 are driven by a controller IC 200C, which can be configured in the same manner as the controller IC 200A and the controller IC 200B.

[0073] Figure 9 is a diagram illustrating the operation of the resonant switched capacitor converter 100C in Figure 8. The resonant switched capacitor converter 100C can switch between a first state φ1 and a second state φ2. In the first state φ1, the switches SW1, SW3, SW5, SW7, and SW9 are on, and the remaining switches SW2, SW4, SW6, SW8, and SW10 are off.

[0074] In the second state φ2, the switches SW1, SW3, SW5, SW7, and SW9 are turned off, and the remaining switches SW2, SW4, SW6, SW8, and SW10 are turned on.

[0075] By alternately repeating the first state φ1 and the second state φ2, the voltage across the LC resonant circuit 106_1 of the capacitor C1 and the inductor L1 becomes 36V, the voltage across the capacitor C2 becomes 24V, and the voltage across the LC resonant circuit 106_2 of the capacitor C3 and the inductor L3 becomes 12V, resulting in an output voltage V of 12V. OUT can be obtained.

[0076] Fig. 10 is an operational waveform diagram of the resonant switched capacitor converter 100C of Fig. 8. Fig. 10 shows the states of the switches SW1 to SW10 and the current i flowing in the first state φ1. φ1 , the current i flowing in the second state φ2 φ2 is shown.

[0077] By operating in a resonant state where ω=ω0, zero current switching (ZCS), i.e., ZCS turn-on and ZCS turn-off, becomes possible, resulting in high efficiency.

[0078] The controller IC 200C of the resonant switched capacitor converter 100C according to the third embodiment can be configured based on the controller IC 200A described in the first embodiment, by simply increasing the number of drivers in the drive circuit 120A of the controller IC 200A to 10. This configuration enables zero current switching and achieves high efficiency, similar to the first embodiment.

[0079] Alternatively, the controller IC 200C of the resonant switched capacitor converter 100C according to the third embodiment may be configured based on the controller IC 200B described in the second embodiment, and the number of drivers in the drive circuit 120B of the controller IC 200B may be increased to 10. This configuration enables zero voltage switching, as in the second embodiment, and achieves high efficiency. OUT <V IN In the range of / 4, the output voltage V OUT to any target level V OUT(REF) can be stabilized to

[0080] Example 4 11 is a circuit diagram of a resonant switched capacitor converter 100D according to a fourth embodiment. This resonant switched capacitor converter 100D has a gain of 1 / 4, similar to the third embodiment, and operates in response to an input voltage V IN is stepped down to 1 / 4 and the output voltage V OUT =V IN Generates / 4.

[0081] The resonant switched capacitor converter 100D has a configuration in which the 1 / 2 resonant switched capacitor converter 100A described in the first embodiment is connected in series in two stages. The resonant switched capacitor converter 100A in the front stage receives an input voltage V IN is multiplied by 1 / 2, and the intermediate voltage V MID The downstream resonant switched capacitor converter 100B generates an intermediate voltage V MID is multiplied by 2, and the output voltage V OUT Generate.

[0082] In the fourth embodiment, a controller IC 200A (or 200B) is provided for each resonant switched capacitor converter 100A. The controller IC 200A (200B) of the preceding resonant switched capacitor converter 100A controls the intermediate voltage V MIDThe controller IC 200A (200B) of the resonant switched capacitor converter 100A controls the switching frequency of the front-stage resonant switched capacitor converter 100A based on the output voltage V OUT Based on this, the switching frequency of the subsequent resonant switched capacitor converter 100A is controlled.

[0083] This configuration allows the 1 / 4 resonant switched capacitor converter to operate with high efficiency.

[0084] Example 5 12 is a circuit diagram of a resonant switched capacitor converter 100E according to a fifth embodiment. This resonant switched capacitor converter 100E has a gain of 1 / 4, similar to the third and fourth embodiments, and operates in response to an input voltage V IN is stepped down to 1 / 4 and the output voltage V OUT =V IN Generates / 4.

[0085] The resonant switched capacitor converter 100E has a configuration in which two 1 / 2 resonant switched capacitor converters 100A are connected in series, as in the fourth embodiment, but in the fifth embodiment, the controller IC 200E for the two resonant switched capacitor converters 100A is integrated into one chip. The controller IC 200E controls the output voltage V OUT Only the output voltage V OUT Based on this, the switching frequencies of both the front and rear stages are controlled in the same way.

[0086] This configuration allows the 1 / 4 resonant switched capacitor converter to operate with high efficiency.

[0087] (Variation) The above-described embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and the processing steps. Such modifications will be described below.

[0088] In the embodiments, a 1 / 2 or 1 / 4 converter has been described, but the application of the present disclosure is not limited to this and can be applied to converters with other gains. It can also be applied to switched capacitor converters with a gain greater than 1.

[0089] (Application) 13 is a diagram showing an example of an electronic device 700 including a resonant switched capacitor converter 100. A suitable example of the electronic device 700 is a server. Originally, a 12V power line was connected to the server, and therefore the internal circuit 710 is designed to operate at 12V. The internal circuit 710 may include a CPU (Central Processing Unit), memory, a LAN (Local Area Network) interface circuit, a DC / DC converter that steps down the 12V voltage, and the like.

[0090] In recent years, there has been a trend to replace the bus voltage from 12 V with 48 V in order to reduce the current flowing through the power lines. In this case, a power supply circuit 720 is required that steps down the 48 V power supply voltage to 12 V. The resonant switched capacitor converter 100 with a gain of 1 / 4 described above can be suitably used for such a power supply circuit 720.

[0091] The electronic device 700 is not limited to a server, but may also be an in-vehicle device. While conventional automobile batteries are mainly 12V or 24V, hybrid vehicles may employ 48V systems, which also require a power supply circuit that converts the 48V battery voltage to 12V or 24V. In such cases, the 1 / 2x or 1 / 4x resonant switched capacitor converter 100 can be suitably used.

[0092] Alternatively, the electronic device 700 may be industrial equipment, office automation equipment, or consumer equipment such as audio equipment.

[0093] The embodiments are merely examples, and it will be understood by those skilled in the art that there are various variations in the combination of each component and each treatment process, and that such variations are also included in the present disclosure and can constitute the scope of the present invention. [Explanation of symbols]

[0094] 100 Resonant Switched Capacitor Converter 102 input lines 104 output lines 106 LC resonant circuit 110 Switch Circuit 120 Drive Circuit 130 Frequency Controller 132 Variable Frequency Oscillator 134 Frequency Adjustment Unit 136 Memory section 138 Comparison circuit 140 Feedback Circuit 150 oscillators 160 Overcurrent protection circuit 200 Controller IC SW switch C capacitor L inductor

Claims

1. 1. A controller circuit for a resonant switched capacitor converter, comprising: an oscillator for generating a clock signal; a drive circuit that drives a plurality of switches that constitute a switch circuit of the resonant switched capacitor converter in response to the clock signal; a frequency controller that controls the oscillation frequency of the oscillator so that a feedback voltage indicating the output voltage of the resonant switched capacitor converter approaches a maximum value under normal conditions; an overcurrent protection circuit that, when detecting an overcurrent state of the resonant switched capacitor converter, disables the control of the oscillation frequency by the frequency controller and changes the oscillation frequency of the oscillator to a predetermined frequency that is away from the resonant frequency; A controller circuit comprising:

2. The frequency controller, for each control cycle, (i) changing the oscillation frequency of the oscillator in one of an upward direction and a downward direction; (ii) when a present value of the feedback voltage in a current control cycle is greater than a past value of the feedback voltage in a control cycle immediately preceding the current control cycle, changing the oscillation frequency of the oscillator in the same direction in the next control cycle; (iii) when the present value of the feedback voltage is decreased from the past value of the feedback voltage, changing the oscillation frequency of the oscillator in the opposite direction in the next control cycle; The controller circuit of claim 1 that performs the process.

3. 3. The controller circuit according to claim 1, wherein the controller circuit is monolithically integrated on a single semiconductor substrate.

4. A resonant switched capacitor converter comprising a controller circuit according to any one of claims 1 to 3.

5. An electronic device comprising the resonant switched capacitor converter according to claim 4.

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