JP2023015850A - Resonance switched capacitor converter, controller circuit thereof and control method, and electronic device using the same - Google Patents

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

The present disclosure relates to resonant switched capacitor converters.

A DC/DC converter or charge pump is used to generate a voltage higher or lower than the power supply voltage. A DC/DC converter that uses an inductor as an energy-storing element can control the output voltage with the inductor, but there is a problem that the switching operation reduces the efficiency.

Applications requiring high efficiency use switched-capacitor converters (charge pumps) that do not require inductors as energy storage elements. As one of these switched capacitor converters, there is known one in which a resonant inductor is added in series with a flying capacitor to perform resonant operation (referred to as a resonant switched capacitor converter). A resonant switched-capacitor converter enables zero-current switching (soft-switching), thereby enabling high-efficiency operation.

A configuration (switched tank converter) in which an inductor is added to a Dickson type charge pump is also known as one form of a resonant switched capacitor converter.

U.S. Pat. No. 9,917,517

SUMMARY OF THE INVENTION It is in this context that one exemplary objective of the present disclosure is to provide a resonant switched capacitor converter with overcurrent protection.

Certain aspects of the present disclosure relate to controller circuits for resonant switched-capacitor converters. The controller circuit includes an oscillator that generates a clock signal, a drive circuit that drives a plurality of switches constituting a switching circuit of the resonant switched capacitor converter according to the clock signal, and an overcurrent state of the resonant switched capacitor converter. and an overcurrent protection circuit that changes the frequency of the clock signal in a direction away from the resonance frequency.

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; changing the switching frequency of the converter away from the resonant frequency.

Arbitrary combinations of the above constituent elements, and mutually replacing constituent elements and expressions in methods, apparatuses, systems, and the like are also effective as embodiments of the present invention.

According to certain aspects of the present disclosure, overcurrent protection can be provided.

FIG. 1 is a circuit diagram of a resonant switched capacitor converter according to an embodiment. FIG. 2 is a diagram showing the relationship between the gain of the resonant switched capacitor converter and the switching frequency ω. FIG. 3 is a circuit diagram of a resonant switched capacitor converter according to Example 1. FIG. FIG. 4 is a time chart explaining the operation of the resonant switched capacitor converter. FIG. 5 is a circuit diagram of a controller IC according to the first embodiment; FIG. 6 is a circuit diagram of a controller IC according to the second embodiment. FIG. 7 is a diagram for explaining the operation of the frequency controller of FIG. 6; FIG. 8 is a circuit diagram of a resonant switched capacitor converter according to the third embodiment. 9 is a diagram illustrating the operation of the resonant switched capacitor converter of FIG. 8. FIG. FIG. 10 is an operating waveform diagram of the resonant switched capacitor converter of FIG. FIG. 11 is a circuit diagram of a resonant switched capacitor converter according to a fourth embodiment. FIG. 12 is a circuit diagram of a resonant switched capacitor converter according to a fifth embodiment. FIG. 13 is a diagram illustrating an example of an electronic device that includes a resonant switched-capacitor converter.

(Overview of embodiment)
SUMMARY OF THE INVENTION Several exemplary embodiments of the disclosure are summarized. This summary presents, in simplified form, some concepts of one or more embodiments, as a prelude to the more detailed description that is presented later, and for the purpose of a basic understanding of the embodiments. The size is not limited. This summary is not a comprehensive overview of all possible embodiments, and it is intended to neither identify key elements of all embodiments nor delineate the scope of some or all aspects. For convenience, "one embodiment" may be used to refer to one embodiment (example or variation) or multiple embodiments (examples or variations) disclosed herein.

A controller circuit for a resonant switched-capacitor converter according to one embodiment includes an oscillator that generates a clock signal, a drive circuit that drives a plurality of switches constituting a switching circuit of the resonant switched-capacitor converter according to the clock signal, and an overcurrent protection circuit that changes the frequency of the clock signal away from the resonant frequency upon detection of an overcurrent condition in the resonant switched capacitor converter.

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

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

With this configuration, by optimizing the switching frequency according to the output voltage of the resonant switched capacitor converter, even if the resonant frequency varies, the resonant switched capacitor converter can be operated in soft switching, improving efficiency. can. Also, in an overcurrent condition, frequency control by the frequency controller can be disabled to move the switching frequency away from the resonant frequency.

In one embodiment, the frequency controller may control the oscillation frequency of the oscillator such that under normal conditions the output voltage of the resonant switched capacitor converter approaches a maximum value. This enables zero current switching (ZCS).

In one embodiment, the frequency controller changes the oscillation frequency of the oscillator to the first direction in the next frequency control cycle when the output voltage of the resonant switched capacitor converter increases as a result of changing the oscillation frequency of the oscillator in the first direction. When the direction is changed and the output voltage of the resonant switched capacitor converter drops, the oscillation frequency of the oscillator may be changed in a second direction opposite the first direction in the next frequency control cycle.

In one embodiment, the frequency controller may change 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. In this case, efficiency can be improved by Zero Voltage Switching (ZVS).

In one embodiment, the frequency controller may change the oscillation frequency of the oscillator such that the output voltage of the resonant switched capacitor converter approaches the target voltage under normal conditions. This allows the output voltage to be set to any voltage level.

In one embodiment, the controller circuit may be monolithically integrated on a single semiconductor substrate. "Integrated integration" includes the case where all circuit components are formed on a semiconductor substrate, and the case where the main components of a circuit are integrated. A resistor, capacitor, or the like may be provided outside the semiconductor substrate. By integrating the circuits on one chip, the circuit area can be reduced and the characteristics of the circuit elements can be kept uniform.

(embodiment)
BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. Moreover, the embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

In this specification, "a state in which member A is connected to member B" refers to a case in which member A and member B are physically directly connected, as well as a case in which member A and member B are electrically connected to each other. It also includes the case of being indirectly connected through other members that do not substantially affect the physical connection state or impair the functions and effects achieved by their combination.

Similarly, "the state in which member C is provided between member A and member B" refers to the case where member A and member C or member B and member C are directly connected, as well as the case where they are electrically connected. It also includes the case of being indirectly connected through other members that do not substantially affect the physical connection state or impair the functions and effects achieved by their combination.

Further, "signal A (voltage, current) corresponds to signal B (voltage, current)" means that signal A has a correlation with signal B. Specifically, (i) signal A is signal B, (ii) signal A is proportional to signal B, (iii) signal A is obtained by level-shifting signal B, (iv) signal A is obtained by amplifying signal B. (v) if signal A is obtained by inverting signal B; (vi) or any combination thereof; It will be understood by those skilled in the art that the range of "depending on" is determined according to the types of signals A and B and the application.

The vertical and horizontal axes of the waveform diagrams and time charts referred to in this specification are enlarged or reduced as appropriate for ease of understanding, and each waveform shown is also simplified for ease of understanding. or exaggerated or emphasized.

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

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

Inductor L1 is connected in series with one of capacitors C1-Cn (flying capacitor) to form an LC resonant circuit. A plurality of inductors may be provided corresponding to a plurality of flying capacitors.

The switch circuit 110 includes an input node IN, an output node OUT, a ground node GND, and a plurality of switches SW. Input voltage V _IN of resonant switched capacitor converter 100 is supplied to input node IN, and output voltage V _OUT of resonant switched capacitor converter 100 is generated at output node OUT. Ground node GND is grounded.

Oscillator 150 generates clock signal CLK. Resonant switched capacitor converter 100 switches in synchronization with this clock signal CLK. That is, the switching frequency of resonant switched capacitor converter 100 is based on the frequency of clock signal CLK (the oscillation frequency of oscillator 150). For example, the oscillation frequency of oscillator 150 may be fixed at or near the resonant frequency ω ₀ of resonant switched capacitor converter 100 . Alternatively, as will be described later, the oscillation frequency of oscillator 150 may be feedback-controlled according to output voltage _VOUT .

The drive circuit 120 drives the switches SW1 to SWm forming the switch circuit 110 in synchronization with the clock signal CLK. The drive circuit 120 includes drivers Dr1-Drm corresponding to the plurality of switches SW1-SWm.

A current detection signal IS indicating the output current I _OUT of the resonant switched capacitor converter 100 is input to the current detection pin CS of the controller IC 200 . For example, a sense resistor RCS may be inserted in the path of the output current _IOUT , and the voltage across the resistor RCS (voltage drop) may be input to the current detection pin _CS as the current detection signal IS.

Overcurrent protection circuit 160 detects an overcurrent state of resonant switched capacitor converter 100 based on current detection signal IS. For example, overcurrent protection circuit 160 may determine an overcurrent state when current detection signal IS exceeds a predetermined threshold. When the overcurrent protection circuit 160 detects an overcurrent state, the overcurrent protection circuit 160 changes the frequency of the clock signal CLK generated by the oscillator 150 away from the resonance frequency.

The above is the configuration of the resonant switched capacitor converter 100 . Next, the operation will be explained.

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

ω ₀ is the resonance frequency, and when the switching frequency ω coincides with the resonance frequency ω ₀ , the gain G becomes 1/2, which is the maximum value, and decreases as it deviates from there.

R represents the impedance of the load of resonant switched capacitor converter 100 . _QL is the Q factor of the circuit and _Z0 is the characteristic impedance.

When the load becomes heavy (when R becomes small), the Q value becomes large, and the gain decrease becomes large when the switching frequency ω _deviates from the resonance frequency ω0.

For example, in a normal state (non-overcurrent state), the oscillation frequency of oscillator 150 is defined within a hatched area (NORMAL) near the resonance frequency _ω0 , and the gain of resonant switched capacitor converter 100 is Close to 1/2. At this time, resonant switched-capacitor converter 100 produces an output voltage V _OUT that is half the input voltage V _IN .

When an overcurrent condition is detected by the overcurrent protection circuit 160, the oscillation frequency of the oscillator 150 is changed away from the resonance frequency _ω0 . In the example of FIG. ₂ , the resonance frequency ω0 is raised to the region labeled OCP. Thereby, the gain of the oscillator 150 can be lowered from 1/2. This allows the output voltage V _OUT of resonant switched capacitor converter 100 to be lowered and the output current I _OUT to be reduced. In addition, in the overcurrent state, the switching frequency may be changed in a direction lower than the resonance frequency _ω0 .

This disclosure extends to various apparatus and methods that can be grasped as the block diagram or circuit diagram of FIG. 1 or derived from the above description, and is not limited to any particular configuration. Hereinafter, more specific configuration examples and embodiments will be described not to narrow the scope of the present disclosure, but to help understand and clarify the essence and operation of the present disclosure and the present invention.

(Example 1)
FIG. 3 is a circuit diagram of the resonant switched capacitor converter 100A according to the first embodiment. Resonant switched-capacitor converter 100A has a gain of 1/2, steps down the input voltage V _IN on input line 102 by 1/2, and outputs on output line 104 an output voltage V _OUT =V _IN /2. occurs. Resonant switched capacitor converter 100A includes two capacitors C1 and C2, one inductor L1, and controller IC 200A. The switch circuit 110A also 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.

The switches SW1 to SW4 are driven by the controller IC200A. In this embodiment, the plurality of switches SW1-SW4 are N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The drive signal for the _i -th switch SWi is denoted as Si, and when _Si is H (high), the switch SWi is on, and when _Si is L (low), the switch SWi is off. do.

Resonant switched capacitor converter 100A can switch 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, the LC resonance circuit 106 including the capacitor C1 and the inductor L1 and the capacitor C2 are connected in series, and the input voltage _VIN is applied across them. When C1=C2, the voltage across each capacitor C1, C2 is charged with V _IN /2.

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 and the capacitor C2 are connected in parallel, and V _OUT =V _IN /2 is generated on the output line 104 .

FIG. 4 is a time chart explaining the operation of resonant switched capacitor converter 100A. FIG. 4 shows the drive signals S ₁ to S ₄ , the resonance current I _RES flowing through the LC resonance circuit 106, the input current I _in , and the output current I _OUT .

When the frequency of the resonance current I _RES (resonance frequency) and the switching frequency match, a state of zero current switching (soft switching) is achieved, enabling highly efficient operation. T _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.

Next, the configuration of the controller IC 200A will be explained.

FIG. 5 is a circuit diagram of the 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-Dr4 corresponding to the four switches SW1-SW4. Drivers Dr1 and Dr3 operate in phase with clock CLK, and drivers Dr2 and Dr4 operate in phase opposite to clock CLK.

Frequency controller 130A includes frequency variable oscillator 132 and frequency adjuster 134 . Variable frequency oscillator 132 corresponds to oscillator 150 in FIG. The frequency adjuster 134 adaptively controls the frequency of the variable frequency oscillator 132 in a normal state based on the feedback voltage V _FB (output voltage V _OUT ) input to the feedback pin FB.

Specifically, frequency adjuster 134 controls the frequency of variable frequency oscillator 132 for each frequency control cycle j so that output voltage V _OUT approaches the maximum value. The frequency adjuster 134 is configured to be able to compare the current value V _FBj of the feedback voltage V _FB with the past value V _FB(j−1) of the feedback voltage V _FB . The frequency adjustment unit 134 includes a storage unit 136 such as a sample hold circuit or memory that holds the past value V _FBj−1 of the feedback voltage V _FB and a comparison circuit 138 .

Frequency adjuster 134 changes the switching frequency, that is, the frequency of frequency variable oscillator 132 in a first direction (for example, upward direction) in a certain frequency control cycle j. A comparison circuit 138 compares the resulting feedback voltage V _FBj with the past feedback voltage V _FBj−1 . As a result of the comparison, when the output voltage V _OUT (feedback voltage V _FB ) increases, the frequency of the variable frequency oscillator 132 is changed in the first direction (upward direction) also in the next frequency control cycle j+1. Conversely, when the output voltage V _OUT (feedback voltage V _FB ) drops, the frequency of the variable frequency oscillator 132 is changed in the second direction (downward direction) opposite to the first direction in the next frequency control cycle j+1. The current value V _FBj in the frequency control cycle j becomes the past value V _FBj in the next frequency control cycle j+1.

Frequency adjuster 134 can maximize output voltage V _OUT by repeating this frequency control cycle. As can be seen from FIG. 2, when the output voltage V _OUT takes the maximum value, the switching frequency ω and the resonance frequency ω ₀ are the same, so zero current switching is possible and the efficiency can be improved.

When the overcurrent detection signal OCP is asserted by the overcurrent protection circuit 160, the operation of the frequency adjustment unit 134 is stopped, and the frequency of the variable frequency oscillator 132 is set to a predetermined frequency _ωOCP that is distant from the resonance frequency _ω0 . be. Thereby, overcurrent protection can be applied.

(Example 2)
FIG. 6 is a circuit diagram of a controller IC 200B according to the second embodiment. Controller IC 200B can be used in resonant switched capacitor converter 100A of FIG. 3 as a replacement for controller IC 200A.

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.

Frequency controller 130B comprises frequency variable oscillator 132 and feedback circuit 140 .

The frequency variable oscillator 132 is a VCO (Voltage Controlled Oscillator) or a DCO (Digital Controlled Oscillator), and oscillates at a frequency corresponding to the signal level of the control signal _SCTRL . Variable frequency oscillator 132 corresponds to oscillator 150 in FIG.

A reference voltage V _REF that defines a target level V _{OUT (REF)} of the output voltage V _OUT is input to the feedback circuit 140 . When the output voltage V _OUT is used as the feedback voltage V _FB as it is, the target level V _{OUT (REF)} of the output voltage V _OUT becomes the reference voltage V _REF .

The feedback circuit 140 controls the frequency of the frequency variable oscillator 132 in a range where ω _> ω0 in a normal state. Since the resonant switched capacitor converter 100A operates in the range of ω _> ω0, its gain operates in a region smaller than 1/2, and the target level V _{OUT (REF)} of the output voltage V _OUT is V _IN /2.

Feedback circuit 140 controls the frequency of variable frequency oscillator 132 so that the error between feedback voltage V _FB and reference voltage V _REF approaches zero. Feedback circuit 140 can be comprised of analog or digital circuitry. For example, feedback circuit 140 includes an error amplifier that amplifies the error between feedback voltage V _FB and reference voltage V _REF and provides control signal S _CTRL to frequency variable oscillator 132 based on the output of the error amplifier. Alternatively, the feedback circuit 140 may be composed of a digital circuit including a PI (proportional-integral) controller or a PID (proportional-integral-derivative) controller.

FIG. 7 is a diagram explaining the operation of the frequency controller 130B of FIG. The operating range of resonant switched-capacitor converter 100A is limited to the range ω _> ω0, within which the target level V _OUT(REF) of output voltage V _OUT is defined.

As a result of the feedback control of frequency controller 130B, the frequency of variable frequency oscillator 132, ie, switching frequency ω of resonant switched capacitor converter 100A, is stabilized at optimum frequency ω _OPT where V _OUT =V _OUT(REF) .

When an overcurrent condition is detected by the overcurrent protection circuit 160, the feedback control by the feedback circuit 140 is stopped and the frequency of the frequency variable oscillator 132 is set to a predetermined frequency ω _OCP set higher than the operating range. . Thereby, overcurrent protection can be applied.

The above is the operation of the controller IC 200B. In Example 1, zero-current switching was achieved by operating at ω ₌ ω0, whereas in Example 2, operating at ω>ω0 enabled _zero -voltage switching. High efficiency operation can be realized.

In Embodiment 1, the output voltage V _OUT is stabilized at a voltage level that is half the input voltage _VIN . Therefore, when the input voltage _VIN fluctuates, the output voltage V _OUT also fluctuates. In contrast, according to the second embodiment, even if the input voltage V _IN fluctuates, the output voltage V _OUT can be stabilized at the target level determined according to the reference voltage V _REF .

(Example 3)
FIG. 8 is a circuit diagram of a resonant switched capacitor converter 100C according to the third embodiment. This resonant switched-capacitor converter _100C is a switched-tank converter and has a gain of 1/4. Generating a voltage V _OUT =V _IN /4.

Resonant switched capacitor converter 100C includes three capacitors C1-C3, two inductors L1 and L3, and controller IC 200C. The switch circuit 110C also includes switches SW1 to SW10. This resonant switched-capacitor converter 100C has a configuration (switched tank converter) in which inductors L1 and L3 are added to a Dickson-type charge pump.

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.

A pair of the fifth switch SW5 and the sixth switch SW6, a pair of the seventh switch SW7 and the eighth switch SW8, and a pair of the ninth switch SW9 and the tenth switch SW10 respectively form inverters INV1 to INV3.

The switches SW1 to SW10 are driven by the controller IC200C. The controller IC 200C can be configured similarly to the controller IC 200A and the controller IC 200B.

FIG. 9 is a diagram for explaining the operation of resonant switched capacitor converter 100C of FIG. 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 turned on and the remaining switches SW2, SW4, SW6, SW8 and SW10 are turned off.

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.

By alternately repeating the first state φ1 and the second state φ2, the voltage across the LC resonance circuit 106_1 of the capacitor C1 and the inductor L1 is 36 V, the voltage across the capacitor C2 is 24 V, and the LC resonance of the capacitor C3 and the inductor L3 is 36 V. The voltage across the circuit 106_2 will be 12V, and an output voltage V _OUT of 12V can be obtained.

FIG. 10 is an operating waveform diagram of resonant switched capacitor converter 100C of FIG. FIG. 10 shows the states of the switches SW1 to SW10, the current i _φ1 flowing in the first state φ1, and the current i _φ2 flowing in the second state φ2.

By operating in the resonance state of ω=ω0, _zero current switching (ZCS), that is, ZCS turn-on and ZCS turn-off, becomes possible, and high efficiency can be obtained.

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, and the number of drivers of the drive circuit 120A of the controller IC 200A is reduced to ten. You can increase it. According to this configuration, as in the first embodiment, zero current switching becomes possible and high efficiency can be obtained.

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 of the drive circuit 120B of the controller IC 200B is ten. should be increased to According to this configuration, as in the second embodiment, zero voltage switching becomes possible and high efficiency can be obtained. Also, in the range of V _OUT <V _IN /4, the output voltage V _OUT can be stabilized at an arbitrary target level V _OUT(REF) .

(Example 4)
FIG. 11 is a circuit diagram of a resonant switched capacitor converter 100D according to the fourth embodiment. This resonant switched-capacitor converter 100D has a gain of 1/4 times as in the third embodiment, steps down the input voltage _VIN of the input line 102 to 1/4 times, and outputs it to the output line 104. Generating a voltage V _OUT =V _IN /4.

The resonant switched capacitor converter 100D has a configuration in which the 1/2 resonant switched capacitor converters 100A described in the first embodiment are connected in series in two stages. The front-stage resonant switched-capacitor converter 100A multiplies the input voltage _VIN by 1/2 to generate an intermediate voltage V-- _MID . A downstream resonant switched-capacitor converter 100B multiplies the intermediate voltage V _MID by a factor of two to produce an output voltage V _OUT .

In Example 4, a controller IC 200A (or 200B) is individually provided for each resonant switched capacitor converter 100A. Controller IC 200A (200B) of resonant switched-capacitor converter 100A in the preceding stage controls the switching frequency of resonant switched-capacitor converter 100A in the preceding stage based on intermediate voltage V _MID . The controller IC 200A (200B) of the subsequent resonant switched capacitor converter 100A controls the switching frequency of the subsequent resonant switched capacitor converter 100A based on the output voltage _VOUT .

According to this configuration, a 1/4 times resonant switched capacitor converter can be operated with high efficiency.

(Example 5)
FIG. 12 is a circuit diagram of a resonant switched capacitor converter 100E according to the fifth embodiment. This resonant switched-capacitor converter 100E has a gain of 1/4 as in the third and fourth embodiments, and steps down the input voltage _VIN of the input line 102 by a factor of 1/4. It produces an output voltage V _OUT =V _IN /4 on line 104 .

Similar to the fourth embodiment, the resonant switched capacitor converter 100E has a configuration in which two stages of 1/2 resonant switched capacitor converters 100A are connected in series. Controller IC 200E of capacitor converter 100A is integrated into one chip. Only the output voltage V _OUT of the latter-stage resonant switched capacitor converter 100A is fed back to the controller IC 200E, and the switching frequencies of both the former and latter stages are similarly controlled based on the output voltage V _OUT .

According to this configuration, a 1/4 times resonant switched capacitor converter can be operated with high efficiency.

(Modification)
Those skilled in the art will understand that the above-described embodiments are examples, and that various modifications can be made to combinations of each component and each processing process. Such modifications will be described below.

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

(Application)
FIG. 13 is a diagram showing an example of an electronic device 700 that includes the resonant switched capacitor converter 100. As shown in FIG. A suitable example of the electronic device 700 is a server. Since a 12V power supply line was originally drawn into the server, the internal circuit 710 is designed to operate at 12V. The internal circuit 710 can include a CPU (Central Processing Unit), a memory, a LAN (Local Area Network) interface circuit, a DC/DC converter that steps down a voltage of 12 V, and the like.

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

Electronic device 700 is not limited to a server, and may be an in-vehicle device. Conventional automobile batteries are mainly 12V or 24V, but hybrid vehicles may adopt a 48V system, and in this case also, a power supply circuit that converts the 48V battery voltage to 12V or 24V is required. be. In such a case, the 1/2 or 1/4 resonant switched capacitor converter 100 can be preferably used.

In addition, the electronic device 700 may be industrial equipment, OA equipment, or consumer equipment such as audio equipment.

The embodiments are examples, and it should be noted that there are various modifications in the combination of each component and each processing process, and such modifications are included in the present disclosure and can constitute the scope of the present invention. It is understood by those skilled in the art.

REFERENCE SIGNS LIST 100 resonant switched capacitor converter 102 input line 104 output line 106 LC resonant circuit 110 switch circuit 120 drive circuit 130 frequency controller 132 variable frequency oscillator 134 frequency adjustment section 136 storage section 138 comparison circuit 140 feedback circuit 150 oscillator 160 overcurrent protection circuit 200 Controller IC
SW Switch C Capacitor L Inductor

Claims (10)

A controller circuit for a resonant switched capacitor converter, comprising:
an oscillator that generates a clock signal;
a drive circuit for driving a plurality of switches constituting a switch circuit of the resonant switched capacitor converter in accordance with the clock signal;
an overcurrent protection circuit that, upon detecting an overcurrent condition of the resonant switched capacitor converter, changes the frequency of the clock signal away from the resonant frequency;
a controller circuit. 2. The controller circuit of claim 1, further comprising a frequency controller that, in normal conditions, controls the oscillation frequency of said oscillator based on the output voltage of said resonant switched capacitor converter. 3. The controller circuit of claim 2, wherein the frequency controller controls the oscillation frequency of the oscillator such that, under normal conditions, the output voltage of the resonant switched capacitor converter approaches a maximum value. When the output voltage of the resonant switched-capacitor converter increases as a result of changing the oscillation frequency of the oscillator in the first direction, the frequency controller changes the oscillation frequency of the oscillator to the first direction in the next frequency control cycle. changing in one direction and changing 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 drops. 4. The controller circuit of claim 3. 3. The controller circuit according to claim 2, wherein said frequency controller changes the oscillation frequency of said oscillator in a region where the oscillation frequency of said oscillator is higher than the resonance frequency of said resonant switched capacitor converter in a normal state. 6. The controller circuit of claim 5, wherein the frequency controller changes the oscillation frequency of the oscillator such that the output voltage of the resonant switched capacitor converter approaches a target voltage under normal conditions. 7. The controller circuit according to claim 1, monolithically integrated on one semiconductor substrate. A resonant switched capacitor converter comprising a controller circuit according to any of claims 1-7. An electronic device comprising the resonant switched capacitor converter according to claim 8 . A method of controlling a resonant switched capacitor converter, comprising:
sensing the output current of the resonant switched capacitor converter;
changing the switching frequency of the resonant switched capacitor converter away from the resonant frequency when the output current exceeds a predetermined threshold;
A control method comprising:

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