Switching power supply device

Abstract

To stabilize output voltage against change of the number of actuation channels of a DC / DC converter.SOLUTION: A switching power supply device (1A) comprises DC / DC converters each having a coil for a plurality of channels and generates output voltage by coil current (IL [i]) of one or more channels based on input voltage. An error amplifier (110) which generates an error signal based on an error between feedback voltage according to the output voltage and feedback reference voltage is shared among the plurality of channels. In the DC / DC converter of each channel, corresponding coil current is controlled on the basis of difference between the error signal (EOUT) and a reference signal (REF [i]) and a detection result of the corresponding coil current. In the DC / DC converter of a reference channel, the reference signal is a basic signal (REF [1]). In the DC / DC converters of other channels, a reference signal (REF [2]) can be switched between the error signal and the reference signal.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a switching power supply device.

Background Art

[0002] There is a switching power supply device provided with a plurality of channels of DC / DC converters. Multiphase control can be performed in this type of switching power supply device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] [Summary] Among the plurality of channels of DC / DC converters, the number of channels of the DC / DC converter to be operated may be increased or decreased according to the load state or the like. A device considering such increase or decrease is required.

[0005] A switching power supply device according to an aspect of the present disclosure is a switching power supply device configured to include a plurality of channels of DC / DC converters each having a coil and generate an output voltage by a coil current of one or more channels based on an input voltage, the switching power supply device comprising: an error amplifier configured to generate an error signal based on an error between a feedback voltage corresponding to the output voltage and a feedback reference voltage; sharing the error amplifier among the plurality of channels; in the DC / DC converter of each channel, controlling a corresponding coil current based on a difference between the error signal and a reference signal and a detection result of the corresponding coil current, or based on a difference between the error signal and a current detection signal that indicates the detection result of the corresponding coil current and is generated with reference to the potential of the reference signal; in the DC / DC converter of a reference channel among the plurality of channels, the reference signal being a basic signal; and in the DC / DC converters of other channels among the plurality of channels, a selector is provided for switching the reference signal between the error signal and the basic signal.

Brief Description of the Drawings

[0006]

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[0007] [Detailed Description] Hereinafter, examples of embodiments of the present disclosure will be specifically described with reference to the drawings. In each of the drawings referred to, the same parts are denoted by the same reference numerals, and redundant descriptions regarding the same parts are omitted in principle. In this specification, for the sake of simplicity of description, the names of information, signals, physical quantities, functional units, circuits, elements, or components, etc. corresponding to the symbols or reference numerals may be omitted or abbreviated by writing the symbols or reference numerals for referring to the information, signals, physical quantities, functional units, circuits, elements, or components, etc.

[0008] First, some terms used in the description of the embodiments of the present disclosure will be explained. "Ground" refers to a reference conductor having a reference potential of 0 V (zero volts) as a reference or the 0 V potential itself. The reference conductor may be formed using a conductor such as metal. The 0 V potential may also be referred to as the ground potential. In the embodiments of the present disclosure, the voltage shown without particularly setting a reference represents the potential seen from the ground.

[0009] "Level" refers to the level of the potential. For any signal or voltage of interest, the high level has a higher potential than the low level. In any signal functioning as a voltage signal, the rise and fall of the signal mean the rise and fall of the potential of the signal. The same applies to other similar expressions.

[0010] Regarding any transistor configured as a FET (field effect transistor) exemplified by a MOSFET, the "on state" refers to a state in which the drain and source of the transistor are conducting, and the "off state" refers to a state in which the drain and source of the transistor are non-conducting (blocked state). The same applies to transistors not classified as FETs. Unless otherwise specified, a MOSFET is understood to be an enhancement-type MOSFET. MOSFET is an abbreviation for "metal-oxide-semiconductor field-effect transistor". Also, unless otherwise specified, in any MOSFET, the back gate may be considered to be short-circuited to the source.

[0011] Hereinafter, for any transistor, the on state and the off state may also be simply expressed as on and off. Also, for any transistor, the period during which the transistor is in the on state is referred to as the on period, and the period during which the transistor is in the off state is referred to as the off period.

[0012] For any signal having a high-level or low-level signal level, the period during which the level of the signal is high is referred to as the high-level period, and the period during which the level of the signal is low is referred to as the low-level period. The same applies to any voltage having a high-level or low-level voltage level.

[0013] The connection between a plurality of parts forming a circuit, such as any circuit element, wiring, node, etc., may be understood to refer to an electrical connection unless otherwise specified.

[0014] When any two voltages to be compared are voltage v1 and v2, "v1>v2" represents that voltage v1 is higher than voltage v2, "v1<v2" represents that voltage v1 is lower than voltage v2, and "v1=v2" represents that the value of voltage v1 is the same as the value of voltage v2. The same applies to other expressions including physical quantities other than voltage.

[0015] FIG. 1 shows the overall configuration of the switching power supply device 1 according to an embodiment of the present disclosure. The switching power supply device 1 receives a supply of a positive input voltage V from a voltage source VS and generates a positive output voltage V by stepping down the input voltage V. Therefore, the output voltage V is lower than the input voltage V. The switching power supply device 1 stabilizes the output voltage V at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. IN and generates a positive output voltage V by stepping down the input voltage V. Therefore, the output voltage V is lower than the input voltage V. The switching power supply device 1 stabilizes the output voltage V at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. IN and generates a positive output voltage V by stepping down the input voltage V. Therefore, the output voltage V is lower than the input voltage V. The switching power supply device 1 stabilizes the output voltage V at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. OUT and generates a positive output voltage V by stepping down the input voltage V. Therefore, the output voltage V is lower than the input voltage V. The switching power supply device 1 stabilizes the output voltage V at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. OUT is lower than the input voltage V. The switching power supply device 1 stabilizes the output voltage V at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. IN is lower than the input voltage V. The switching power supply device 1 stabilizes the output voltage V at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. OUT at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. TG at a target voltage V having a predetermined positive DC voltage value. Therefore, in the steady state, the output voltage V is the target voltage V. OUT is the target voltage V. TGIt substantially coincides. The switching power supply device 1 has n DC / DC converters. The n DC / DC converters consist of the DC / DC converters of the first to nth channels. n represents an arbitrary integer of 2 or more.

[0016] The switching power supply device 1 is composed of a power control device 2 that controls the operation of the switching power supply device 1 and a plurality of discrete components externally connected to the power control device 2. The DC / DC converters of the first to nth channels are formed by the power control device 2 and the plurality of discrete components. The plurality of discrete components include coils L for n channels, output capacitors C OUT and feedback resistors R1 and R2. The power control device 2 is provided with switching control circuits 20 for n channels and output stages MM for n channels, and further an error amplifier 10 and a management circuit 30 are provided. Each channel's DC / DC converter includes one switching control circuit 20, one output stage MM, and one coil L. The error amplifier 10, the management circuit 30, the output capacitor C OUT and the feedback resistors R1 and R2 are shared among the first to nth channels (shared by the DC / DC converters of the first to nth channels). That is, a single error amplifier 10 is commonly used among the DC / DC converters of the first to nth channels. The management circuit 30, the output capacitor C OUT and the feedback resistors R1 and R2 are the same.

[0017] The power supply control device 2 is an electronic component including a semiconductor chip having a semiconductor integrated circuit formed on a semiconductor substrate, a housing (package) that houses the semiconductor chip, and a plurality of external terminals that are exposed from the housing to the outside of the power supply control device 2. The power supply control device 2 is formed by encapsulating the semiconductor chip in a housing (package) made of resin. Each circuit provided in the power supply control device 2 is included in the semiconductor integrated circuit. In FIG. 1, as part of the plurality of external terminals included in the power supply control device 2, an input terminal IN, a ground terminal GND, and a feedback terminal FB are shown, and a plurality of switch terminals SW are shown. However, other external terminals are also provided in the power supply control device 2. The power supply control device 2 is provided with switch terminals SW for each channel. Therefore, the power supply control device 2 is provided with a total of n switch terminals SW corresponding to the first to nth channels. An input voltage V IN is applied to the input terminal IN. The ground terminal GND is connected to the ground.

[0018] In each channel, the output stage MM has a series circuit of a transistor MH that is a high-side transistor and a transistor ML that is a low-side transistor. In each channel, the first end of the coil L is connected to the corresponding switch terminal SW. The second ends of the coils L in all channels are commonly connected to the output terminal OUT. The voltage generated at the output terminal OUT is the output voltage V OUT .

[0019] An output capacitor C OUT is inserted between the output terminal OUT and the ground. That is, the first end of the output capacitor C OUT is connected to the output terminal OUT, and the second end of the output capacitor C OUT is connected to the ground. A load LD is connected to the output terminal OUT. The load LD is an arbitrary load driven based on the output voltage V OUT . The current supplied from the output terminal OUT to the load LD (i.e., the output current of the switching power supply device 1) is referred to as a load current I OUT . Also, in each coil L, the current flowing through the coil L is referred to as a coil current IL.

[0020] The first terminal of the feedback resistor R1 is connected to the output terminal OUT, the second terminal of the feedback resistor R1 is connected to the first terminal of the feedback resistor R2, and the second terminal of the feedback resistor R2 is connected to the ground. At the connection node between the feedback resistors R1 and R2, a feedback voltage V OUT corresponding to the output voltage V FB is generated. The feedback terminal FB is connected to the connection node between the feedback resistors R1 and R2 and receives the feedback voltage V FB . The feedback voltage V FB is a voltage division of the output voltage V OUT and thus is proportional to the output voltage V OUT . A feedback voltage generation circuit that generates the feedback voltage V FB is formed by the feedback resistors R1 and R2. The feedback resistors R1 and R2 can be incorporated in the power control device 2. Note that the output voltage V OUT itself may be used as the feedback voltage V FB . In any case, the feedback voltage V FB is a voltage corresponding to the output voltage V OUT .

[0021] The feedback voltage V FB is input to the error amplifier 10. Also, a feedback reference voltage V REF is input to the error amplifier 10. The feedback reference voltage V REF is generated within the power control device 2 based on the input voltage V IN and has a predetermined positive DC voltage value. The error amplifier 10 compares the feedback voltage V FB with the feedback reference voltage V REF and generates and outputs an error signal EOUT, which is a voltage signal corresponding to the error between the feedback voltage V FB and the feedback reference voltage V REF . The error signal EOUT is commonly supplied to the switching control circuits 20 for all channels.

[0022] A set consisting of one switching control circuit 20, one output stage MM, and one coil L is provided with an output capacitor C OUTIt collaborates to form a DC / DC converter for one channel that performs current-mode control. In the DC / DC converter of each channel, the switching control circuit 20 performs switching control of the output stage MM based on the error signal EOUT and the information of the corresponding coil current IL (coil current information), thereby reducing the difference between the output voltage V OUT and the target voltage V TG so as to (the output voltage V OUT matches the target voltage V TG ), and controls the corresponding coil current IL. In the switching power supply device 1, multi-phase control can be performed by shifting the phase of the switching control among a plurality of channels. When multi-phase control is performed, the switching power supply device 1 functions as a multi-phase DC / DC converter.

[0023] The management circuit 30 controls the operation of the DC / DC converter of each channel. Multi-phase control is realized under the control of the management circuit 30 (details will be described later).

[0024] Hereinafter, when it is necessary to distinguish n switching control circuits 20, as shown in FIG. 2, the n switching control circuits 20 are referred to as switching control circuits 20[1] to 20[n]. Similarly, the n output stages MM can be referred to as output stages MM[1] to MM[n]. Similarly, the n switch terminals SW may be referred to as switch terminals SW[1] to SW[n], and the n coils L may be referred to as coils L[1] to L[n]. The switching control circuit 20[i], the output stage MM[i], the switch terminal SW[i], and the coil L[i] are the switching control circuit 20, the output stage MM, the switch terminal SW, and the coil L in the DC / DC converter of the i-th channel. i represents an arbitrary integer. Also, the coil current IL flowing through the coil L[i] is particularly referred to as the coil current IL[i].

[0025] The output stages MM of all channels have the same configuration as each other. As described above, each output stage MM includes transistors MH and ML. The transistors MH and ML are N-channel MOSFETs. In each output stage MM, the transistors MH and ML are a pair of switching elements connected in series between the input terminal IN and the ground terminal GND (in other words, the ground). The transistor MH is provided on the higher potential side than the transistor ML. Specifically, in each output stage MM, the drain of the transistor MH is connected to the input terminal IN to receive the supply of the input voltage V IN . In each output stage MM, the source of the transistor MH and the drain of the transistor ML are commonly connected to the corresponding switch terminal SW. Therefore, the source of the transistor MH and the drain of the transistor ML in the output stage MM[i] are commonly connected to the switch terminal SW[i]. In each output stage MM, the source of the transistor ML is connected to the ground terminal GND (therefore, the ground). Note that a current detection resistor may be inserted between the source of the transistor ML and the ground terminal GND.

[0026] The transistor MH functions as an output element (output transistor), and the transistor ML functions as a rectifying element (synchronous rectifying transistor). In the switching control of the output stage MM, the output element (MH) and the rectifying element (ML) are alternately turned on and off.

[0027] In each output stage MM, by alternately turning on and off the transistors MH and ML by switching control, the input voltage V IN is switched, and as a result, a rectangular-wave switch voltage appears at the corresponding switch terminal SW. The coil L and the output capacitor C OUT connected to the switch terminal SW constitute a rectifying and smoothing circuit that rectifies and smooths the rectangular-wave switch voltage appearing at the switch terminal SW. In each channel, the switch terminal SW is connected to the first end of the corresponding coil L. That is 、 the switch terminal SW[i] is connected to the first end of the coil L[i]. All the second ends of the coils L[1] to L[n] are commonly connected to the output terminal OUT.

[0028] In each channel, during the on-period of transistor MH, coil current IL flows through the channel of transistor MH (between the drain and the source), and then, during the off-period of transistor MH, coil current IL flows through the channel of transistor ML or the parasitic diode of transistor ML.

[0029] By switching and controlling output stage MM, input voltage V IN is power-converted to output voltage V OUT When the switching control circuits 20 of two or more channels perform switching control simultaneously, input voltage V IN is converted to output voltage V OUT by the cooperation of the DC / DC converters of the two or more channels.

[0030] In each channel, switching control circuit 20 controls the on / off states of transistors MH and ML respectively by supplying gate signals GH and GL as drive signals to the gates of transistors MH and ML. Transistors MH and ML are turned on and off according to gate signals GH and GL. When gate signal GH is at a high level, transistor MH is in an on state, and when gate signal GH is at a low level, transistor MH is in an off state. Similarly, when gate signal GL is at a high level, transistor ML is in an on state, and when gate signal GL is at a low level, transistor ML is in an off state. Basically, transistors MH and ML are turned on and off alternately, but transistors MH and ML may be both maintained in an off state. Transistors MH and ML are not simultaneously turned on.

[0031] Hereinafter, in the output stage MM of any channel, a state in which the transistor MH is turned on and the transistor ML is turned off is referred to as an output high state, a state in which the transistor MH is turned off and the transistor ML is turned on is referred to as an output low state, and a state in which both the transistors MH and ML are turned off is referred to as a both-off state. Note that, for any i-th channel, it is considered that the coil current IL[i] in the direction from the switch terminal SW[i] to the output terminal OUT has a positive polarity, and the coil current IL[i] in the direction from the output terminal OUT to the switch terminal SW[i] has a negative polarity.

[0032] In each channel, the switching control circuit 20[i] can execute a current detection process for detecting the coil current IL[i], and obtains information on the coil current IL[i] (coil current information) by the current detection process. The switching control circuit 20[i] can detect the coil current IL[i] based on the voltage drop of a current detection resistor inserted in the path through which the coil current IL[i] flows. The current detection resistor can be the on-resistance of the transistor MH or ML, or may be a resistance element provided separately from the transistors MH and ML. In the current detection process, the switching control circuit 20[i] may be able to detect the average current value of the coil current IL[i]. For example, in the current detection process, the switching control circuit 20[i] can detect the average current value of the coil current IL[i] by detecting the value of the coil current IL[i] at exactly the middle timing during the on-period of the transistor ML in the output stage MM[i]. Alternatively, for example, in the current detection process, the switching control circuit 20[i] may detect the average current value of the coil current IL[i] by detecting the value of the coil current IL[i] at exactly the middle timing during the on-period of the transistor MH.

[0033] Although not particularly shown, the power supply control device 2 is provided with an internal power supply circuit that generates various internal power supply voltages based on the input voltage V IN and each circuit in the power supply control device 2 is based on the input voltage V INOr it is driven based on the internal power supply voltage. In each output stage MM, the gate signal GL is a signal referenced to the ground potential, while the gate signal GH is a signal referenced to the potential of the switch terminal SW. The low-level gate signal GH has the potential of the switch terminal SW, and the high-level gate signal GH is higher by a predetermined voltage when viewed from the potential of the switch terminal SW. The predetermined voltage here is larger than the gate threshold voltage of the transistor MH. A boost power supply for generating the gate signal GH can be generated using a well-known bootstrap circuit (not shown). The transistor MH may be configured with a P-channel type MOSFET, in which case a boost power supply is not required.

[0034] Also, as a modification, a diode rectification method may be adopted in the DC / DC converter of each channel. In this case, as a rectifying element, instead of the transistor ML, a synchronous rectifying diode having an anode connected to the ground and a cathode connected to the switch terminal SW is used. In this case, only the output element (MH) is turned on and off in the switching control of the output stage MM.

[0035] The management circuit 30 can individually operate or stop the DC / DC converters of the first to nth channels. For the DC / DC converter of an arbitrary channel, the state in which the DC / DC converter is operating is referred to as the operating state, and the state in which the DC / DC converter is stopped is referred to as the stopped state. The period during which the DC / DC converter of the i-th channel is in the operating state is referred to as the operating period of the DC / DC converter of the i-th channel, and the period during which the DC / DC converter of the i-th channel is in the stopped state is referred to as the stop period of the DC / DC converter of the i-th channel. During the operating period of the DC / DC converter of the i-th channel, the switching control circuit 20[i] executes the switching control of the output stage MM[i], and the state of the output stage MM[i] switches between the output high state and the output low state. During the stop period of the DC / DC converter of the i-th channel, the switching control of the output stage MM[i] by the switching control circuit 20[i] is stopped, and the state of the output stage MM[i] is fixed in the both-off state.

[0036] Among the DC / DC converters of the first to the n-th channels, the total number of DC / DC converters in the operating state is referred to as the number of operating channels NUM. The management circuit 30 can control the number of operating channels NUM to any value less than or equal to n. When the number of operating channels NUM is 1, only the DC / DC converter of the first channel corresponding to the reference channel among the DC / DC converters of the first to the n-th channels is in the operating state, and the DC / DC converters of the second to the n-th channels are in the stopped state. When the number of operating channels NUM is n, all the DC / DC converters of the first to the n-th channels are in the operating state. When the number of operating channels NUM is an integer value i satisfying "1 < i < n", among the DC / DC converters of the first to the n-th channels, the DC / DC converters of the first to the i-th channels are in the operating state, and the DC / DC converters of the (i + 1)-th to the n-th channels are in the stopped state.

[0037] The management circuit 30 can variably set the number of operating channels NUM based on the information of the coil current IL[i] obtained by the current detection process. That is, for example, when "NUM = 1", the management circuit 30 monitors the coil current IL[1], and when it is detected that the value of the coil current IL[1] (for example, the average current value of the coil current IL[1]) is greater than a predetermined upper threshold value, the number of operating channels NUM is switched from "1" to "2". The same applies when switching the number of operating channels NUM from "2" to "3". Conversely, for example, when "NUM = 2", the management circuit 30 monitors the coil currents IL[1] and IL[2], and when it is detected that the value of the coil current IL[1] or IL[2] (for example, the average current value of the coil current IL[1] or IL[2]) is less than a predetermined lower threshold value, the number of operating channels NUM is switched from "2" to "1". The same applies when switching the number of operating channels NUM from "3" to "2". The lower threshold value is smaller than the upper threshold value.

[0038] Alternatively, for example, the management circuit 30 may variably set the number of operating channels NUM according to a command received by the power control device 2. An external circuit (e.g., a microcomputer) may be connected to the power control device 2 via a communication bus, and the above command is transmitted from the external circuit to the power control device 2. Further alternatively, for example, an external setting terminal for setting the number of operating channels NUM may be included in the external terminals of the power control device 2. In this case, the management circuit 30 may set the number of operating channels NUM based on an input signal to the external setting terminal (e.g., the level of the voltage supplied to the external setting terminal).

[0039] <<Reference Example>> Prior to describing a detailed configuration example of the switching power supply device 1 according to the present embodiment, a reference switching power supply device 901 according to a reference example will be described. FIG. 3 is a configuration diagram of the reference switching power supply device 901. The reference switching power supply device 901 is a two-channel multi-phase DC / DC converter that generates an output voltage Vout from an input voltage Vin. In the reference switching power supply device 901, an error signal Eout representing the error between the feedback voltage based on the output voltage Vout and a predetermined voltage is generated, and the common error signal Eout is supplied to the DC / DC converter 910 of one channel and the DC / DC converter 920 of the other channel.

[0040] In the DC / DC converter 910, a voltage Vca is generated based on information on the coil current ILa of the error signal Eout (coil current information Isnsa), and the duty ratio of the output stage MMa is controlled based on the comparison result between the voltage Vca and the ramp voltage Vra. In the DC / DC converter 920, a voltage Vcb is generated based on information on the coil current ILb of the error signal Eout (coil current information Isnsb), and the duty ratio of the output stage MMb is controlled based on the comparison result between the voltage Vcb and the ramp voltage Vrb.

[0041] In the DC / DC converter 910, an increase in the error signal Eout increases the coil current ILa through an increase in the duty ratio of the output stage MMa, and a decrease in the error signal Eout decreases the coil current ILa through a decrease in the duty ratio of the output stage MMa. The same applies to the DC / DC converter 920. That is, in each channel, the error signal Eout functions to control the coil current, and the coil current is controlled by the error signal Eout. By sharing the error signal Eout among a plurality of channels, the magnitudes of the coil currents of each channel can be controlled to be substantially the same. Also, the switching timing can be dispersed by making the waveforms of the clock signal and the ramp voltage different among a plurality of channels.

[0042] Assume that the potential of the coil current information Isnsa when the coil current ILa is zero and the potential of the coil current information Isnsb when the coil current ILb is zero match the potential of the reference signal ref. Then, there is a linear function relationship between the error signal Eout and the coil currents (ILa, ILb) as shown in FIG. 4.

[0043] In the reference switching device 901, the number of channels of the DC / DC converter to be operated may be increased or decreased.

[0044] FIG. 5 shows various signal waveforms and the like when the number of channels of the DC / DC converter to be operated is increased from 1 to 2 in the reference switching device 901. In FIG. 5, for the sake of illustration, the solid line waveform representing the coil current ILa and the broken line waveform representing the coil current ILb are shown with a slight vertical shift. Also, the ripple of the coil current and the like is omitted in FIG. 5. In the first initial state, only the DC / DC converter 910 is operating and “Iout>0”. At this time, the error signal Eout is higher than the reference signal ref, and the coil current ILa is maintained at a current corresponding to the potential of the error signal Eout (equivalent to Iout). Thereafter, when the operation of the DC / DC converter 920 is started in addition to the DC / DC converter 910, the coil current ILb rapidly rises to a current corresponding to the potential of the error signal Eout (equivalent to Iout). At that time, since “ILa = ILb = Iout” temporarily, as a result, a current twice the load current Iout is output from the reference switching device 901, and an overshoot occurs in the output voltage Vout (becomes higher than the target voltage). The overshoot of the output voltage Vout causes a decrease in the error signal Eout, so that the output voltage Vout gradually decreases to the target voltage over time.

[0045] FIG. 6 shows various signal waveforms and the like when the number of channels of the DC / DC converter to be operated is decreased from 2 to 1 in the reference switching device 901. In FIG. 6, for the sake of illustration, the solid line waveform representing the coil current ILa and the broken line waveform representing the coil current ILb are shown with a slight vertical shift. Also, the ripple of the coil current and the like is omitted in FIG. 6. In the second initial state, both the DC / DC converters 910 and 920 are operating and are stable at “ILa = ILb = Iout / 2”. Thereafter, when the operation of the DC / DC converter 920 is stopped, the coil current ILb quickly becomes zero. At that time, since only the coil current ILa equal to half of the output current Iout is temporarily output from the reference switching device 901, an undershoot occurs in the output voltage Vout (becomes lower than the target voltage). The undershoot of the output voltage Vout causes an increase in the error signal Eout, so that the output voltage Vout gradually rises to the target voltage over time.

[0046] Thus, when changing the total number of DC / DC converters to be operated in the reference switching device 901, a large overshoot or undershoot occurs in the output voltage Vout. After the occurrence of the overshoot or undershoot, the output voltage Vout is returned to the target voltage by feedback control, but it takes a long time for the output voltage Vout to stabilize.

[0047] The switching power supply device 1 according to the present embodiment has a unique configuration that contributes to suppressing the above-described overshoot or undershoot. Hereinafter, among a plurality of embodiments, several specific configuration examples, operation examples, application technologies, modification technologies, etc. related to the switching power supply device 1 will be described. The matters described above in the present embodiment are applied to the following respective embodiments (except for matters related to the reference example and the reference switching device 901) as long as there is no particular description and no contradiction. In each embodiment, when there is a matter that contradicts the above-described matters, the description in each embodiment may be prioritized. Also, as long as there is no contradiction, among the plurality of embodiments shown below, the matters described in any one embodiment can be applied to any other embodiment (that is, it is also possible to combine any two or more of the plurality of embodiments).

[0048] <<Embodiment EX_A1>> Embodiment EX_A1 will be described. FIG. 7 is an example of the switching power supply device 1 and is a configuration diagram of the switching power supply device 1A according to Embodiment EX_A1. The switching power supply device 1A includes an error amplifier 110 and a management circuit 130 as the error amplifier 10 and the management circuit 30 in FIG. 1, and includes a switch control circuit 120 as the switch control circuit 20 in FIG. 1. The error signal EOUT in the switching power supply device 1A is generated by the error amplifier 110. In Embodiment EX_A1, it is assumed that "n = 2".

[0049] The switch control circuit 120 in the DC / DC converter of the i-th channel is particularly referred to as the switch control circuit 120[i]. Each switch control circuit 120 includes an amplifier 121, a comparator 122, a control logic 123, a gate drive circuit 124, and a current detection circuit 125. The amplifier 121, comparator 122, control logic 123, gate drive circuit 124, and current detection circuit 125 in the switch control circuit 120[i] are particularly referred to as the amplifier 121[i], comparator 122[i], control logic 123[i], gate drive circuit 124[i], and current detection circuit 125[i], respectively. The switching power supply device 1A further includes a selector 140[2] and a filter 150[2]. The selector 140[2] and the filter 150[2] are provided in the power control device 2 (see FIG. 1). The selector 140[2] and the filter 150[2] can also be understood as being included in the components of the DC / DC converter of the second channel. Each amplifier 121 includes first and second non-inverting input terminals, first and second inverting input terminals, and an output terminal. Each comparator 122 includes a non-inverting input terminal, an inverting input terminal, and an output terminal.

[0050] The error amplifier 110 includes an inverting input terminal that receives the feedback voltage V FB , a non-inverting input terminal that receives the feedback reference voltage V REF , and an output terminal. The error amplifier 110 compares the feedback voltage V FB with the feedback reference voltage V REF , and generates an error signal EOUT by amplifying the error between the feedback voltage V FB and the feedback reference voltage V REF . The error signal EOUT is an analog voltage signal. The error amplifier 110 increases the error signal EOUT when "V FB = V REF " holds and "V FB < V REF " holds, and decreases the error signal EOUT when "V FB > V REF " holds, based on the establishment state of "V FB = V REF ".

[0051] The management circuit 130 can generate and output a clock signal CLK for n channels and a ramp voltage VR for n channels. In Embodiment EX_A1, since "n = 2", the clock signal CLK for n channels consists of the clock signal CLK[1] of the first channel and the clock signal CLK[2] of the second channel, and the ramp voltage VR for n channels consists of the ramp voltage VR[1] of the first channel and the ramp voltage VR[2] of the second channel. The clock signal CLK for n channels is a rectangular wave signal having a common switching frequency f SW and has alternating high and low levels.

[0052] However, the management circuit 130 outputs a rectangular wave signal having a switching frequency f SW only as the clock signal CLK[i] during the operation period of the DC / DC converter of the i-th channel, and stops the output of the clock signal CLK[i] during the stop period of the DC / DC converter of the i-th channel. During the stop period of the output of the clock signal CLK[i], it can be considered that the level of the clock signal CLK[i] is fixed at the low level. Also, during the stop period of the DC / DC converter of the i-th channel, the management circuit 130 also fixes the level of the ramp voltage VR[i] at a predetermined level. Incidentally, a selection signal SEL[2] is generated by the management circuit 130, and the selection signal SEL[2] is supplied to the selector 140[2].

[0053] FIG. 8 shows the waveforms of the clock signals CLK[1] and CLK[2] and the ramp voltages VR[1] and VR[2], and the state transitions of the output stages MM[1] and MM[2] during the operation periods of the DC / DC converters of the first and second channels. During the operation periods of the DC / DC converters of the first and second channels, the clock signals CLK[1] and CLK[2] are rectangular wave signals with a 180° phase shift from each other. The duty of the clock signals CLK[1] and CLK[2] is arbitrary.

[0054] During the operation period of the DC / DC converter of the first channel, the management circuit 130 sets the level of the ramp voltage VR[1] to a predetermined lower limit level in synchronization with the transition of the clock signal CLK[1] from the low level to the high level, and thereafter monotonically increases the ramp voltage VR[1] at a predetermined rate of increase. During the rising process of the ramp voltage VR[1], the voltage VC[1] generated in the switch control circuit 120[1] is compared with the ramp voltage VR[1], and the switch control circuit 120[1] controls the output stage MM[1] to the output high state during the period when "VC[1]>VR[1]" holds, and controls the output stage MM[1] to the output low state during the period when "VC[1]<VR[1]" holds. During the operation period of the DC / DC converter of the first channel, the input voltage V IN is pulse-width modulated by the output stage MM[1], thereby generating a pulsating coil current IL[1].

[0055] The same applies to the second channel. That is, during the operation period of the DC / DC converter of the second channel, the management circuit 130 sets the level of the ramp voltage VR[2] to a predetermined lower limit level in synchronization with the transition of the clock signal CLK[2] from the low level to the high level, and thereafter monotonically increases the ramp voltage VR[2] at a predetermined rate of increase. During the rising process of the ramp voltage VR[2], the voltage VC[2] generated in the switch control circuit 120[2] is compared with the ramp voltage VR[2], and the switch control circuit 120[2] controls the output stage MM[2] to the output high state during the period when "VC[2]>VR[2]" holds, and controls the output stage MM[2] to the output low state during the period when "VC[2]<VR[2]" holds. During the operation period of the DC / DC converter of the second channel, the input voltage V IN is pulse-width modulated by the output stage MM[2], thereby generating a pulsating coil current IL[2].

[0056] The internal configuration of the switch control circuit 120 is common among a plurality of channels. Therefore, the configuration and operation of the switch control circuit 120[i], which is the switch control circuit 120 of an arbitrary channel, will be described.

[0057] In amplifier 121[i], an error signal EOUT is input to the first non-inverting input terminal, a reference signal REF[i] is input to the first inverting input terminal, a signal I SNSN [i] is input to the second non-inverting input terminal, and a signal I SNSP [i] is input to the second inverting input terminal. The reference signal REF[i] and the signals I SNSN [i] and I SNSP [i] are each analog voltage signals. Amplifier 121[i] outputs a voltage VC[i] from its output terminal based on the voltage difference between the first non-inverting input terminal and the first inverting input terminal and the voltage difference between the second non-inverting input terminal and the second inverting input terminal.

[0058] The voltage VC[i] from amplifier 121[i] is input to the non-inverting input terminal of comparator 122[i], and the ramp voltage VR[i] from management circuit 130 is input to the inverting input terminal of comparator 122[i]. Comparator 122[i] compares the voltage VC[i] with the ramp voltage VR[i] and outputs a signal PWM[i] indicating their high-low relationship from its output terminal. Comparator 122[i] outputs a high-level signal PWM[i] during the period when "VC[i]>VR[i]" holds, and outputs a low-level signal PWM[i] during the period when "VC[i]<VR[i]" holds. When "VC[i]=VR[i]" holds, the signal PWM[i] has a high level or a low level.

[0059] A clock signal CLK[i] and a signal PWM[i] are input to control logic 123[i]. The clock signal CLK[i] is supplied from management circuit 130 to control logic 123[i]. However, management circuit 130 can also stop supplying the clock signal CLK[i] to control logic 123[i]. During the period when the clock signal CLK[i] is supplied to control logic 123[i], the DC / DC converter of the i-th channel is in an operating state, and during the period when the supply of the clock signal CLK[i] to control logic 123[i] is stopped, the DC / DC converter of the i-th channel is in a stopped state.

[0060] During the period when the clock signal CLK[i] is supplied to the control logic 123[i], the control logic 123[i] uses the gate drive circuit 124[i] to supply gate signals GH and GL based on the clock signal CLK[i] and the signal PWM[i] to the gates of the transistors MH and ML of the output stage MM[i], thereby performing the switching of the output stage MM[i]. The gate drive circuit 124[i] can be composed of a level shifter, a high-side driver, and a low-side driver. During the operating period of the DC / DC converter of the i-th channel, in the high-level period of the signal PWM[i], the output stage MM[i] is controlled to the output high state, and in the low-level period of the signal PWM[i], the output stage MM[i] is controlled to the output low state. During the period when the supply of the clock signal CLK[i] to the control logic 123[i] is stopped, the output stage MM[i] is fixed to the both-off state.

[0061] The current detection circuit 125[i] detects the coil current IL[i] and generates and outputs signals I SNSN [i] and I SNSP [i]. When the DC / DC converter of the i-th channel is in the operating state, the coil current IL[i] varies in synchronization with the switching of the output stage MM[i]. That is, when the output stage MM[i] is in the output high state, the coil current IL[i] increases monotonically, and when the output stage MM[i] is in the output low state, the coil current IL[i] decreases monotonically. The current detection circuit 125[i] detects the average current value of the coil current IL[i] and differentially outputs a signal indicating the average current value of the coil current IL[i].

[0062] The signal output from the current detection circuit 125[i] is a differential signal composed of signals I SNSP [i] and I SNSN [i]. Signals I SNSP [i] and I SNSN [i] are both analog voltage signals, and the voltage difference (I SNSP [i] - I SNSN [i]) represents the average current value of the detected coil current IL[i]. The voltage difference (I SNSP [i] - ISNSN [i] has a value obtained by multiplying the average current value of the detected coil current IL[i] by a positive proportionality coefficient. Note that any detection method can be used as a method for detecting the average current value of the coil current IL[i], including known methods (for example, the method shown in US11,196,343B2).

[0063] Amplifier 121[i] represents the voltage difference (EOUT - REF[i]) representing the potential of the error signal EOUT with respect to the potential of the reference signal REF[i], as the voltage difference (I SNSP [i] - I SNSN [i]) is compared. Then, amplifier 121[i] operates to increase the voltage VC[i] as the voltage difference (EOUT - REF[i]) becomes higher than the voltage difference (I SNSP [i] - I SNSN [i]), and decrease the voltage VC[i] as the voltage difference (EOUT - REF[i]) becomes lower than the voltage difference (I SNSP [i] - I SNSN [i]). Therefore, during the operating period of the DC / DC converter of the i-th channel, feedback control works so that the voltage difference (EOUT - REF[i]) matches the voltage difference (I SNSP [i] - I SNSN [i]). SNSP [i] - I SNSN [i])

[0064] That is, during the operating period of the DC / DC converter of the i-th channel, when the error signal EOUT increases based on the decrease in the output voltage V OUT such that "EOUT - REF[i] > I SNSP [i] - I SNSN [i]", the output duty of the output stage MM[i] increases through the increase in the voltage VC[i], and the increase in the output duty of the output stage MM[i] increases the voltage difference (I SNSP [i] - I SNSN [i]) through the increase in the coil current IL[i]. Conversely, during the operating period of the DC / DC converter of the i-th channel, when the output voltage V OUTBased on the rise, the error signal EOUT decreases, resulting in "EOUT-REF[i]<I SNSP [i]-I SNSN [i]". When this occurs, the output duty of the output stage MM[i] decreases through the decrease in the voltage VC[i]. The decrease in the output duty of the output stage MM[i] reduces the voltage difference (I SNSP [i]-I SNSN [i]) through the decrease in the coil current IL[i]. Note that the output duty of the output stage MM[i] refers to the ratio of the period during which the output stage MM[i] is in the output high state to the sum of the period during which the output stage MM[i] is in the output high state and the period during which the output stage MM[i] is in the output low state.

[0065] During the operating period of the DC / DC converter of the i-th channel, through the feedback control as described above, the voltage differences (EOUT-REF[i]) and (I SNSP [i]-I SNSN [i]) are stabilized in a balanced state. That is, during the operating period of the DC / DC converter of the first channel, the switching control circuit 120[1] controls the switching of the output stage MM[1] so that the voltage differences (EOUT-REF[1]) and (I SNSP [1]-I SNSN [1]) are equal (i.e., to reduce the error between the former voltage difference and the latter voltage difference), thereby controlling the average current value of the coil current IL[1]. Similarly, during the operating period of the DC / DC converter of the second channel, the switching control circuit 120[2] controls the switching of the output stage MM[2] so that the voltage differences (EOUT-REF[2]) and (I SNSP [2]-I SNSN [2]) are equal (i.e., to reduce the error between the former voltage difference and the latter voltage difference), thereby controlling the average current value of the coil current IL[2]. However, the reference signal REF[1] is a specific reference signal (basic signal) as a basis and has a fixed potential, while the reference signal REF[2] is a reference signal whose potential can vary.

[0066] FIG. 9 shows the relationship between the error signal EOUT and the coil current IL[i] during the operation period of the DC / DC converter of the i-th channel. During the operation period of the DC / DC converter of the i-th channel, if the transient state is ignored, the average current value of the coil current IL[i] has a value obtained by multiplying a positive predetermined coefficient by the voltage difference (EOUT - REF[i]).

[0067] In Embodiment EX_A1, unless otherwise specified, the above description assumes that the DC / DC converters of each channel are in an operating state (that is, the number of operating channels NUM is 2). When changing the number of operating channels NUM, in order to suppress overshoot or undershoot as described above, the selector 140[2] and the filter 150[2] are provided.

[0068] The selector 140[2] selects either the error signal EOUT or the reference signal REF[1] according to the selection signal SEL[2]. The selector 140[2] inputs the selected signal as the signal FLT IN [2] to the filter 150[2]. The filter 150[2] is a low-pass filter that generates a filter signal by performing a low-pass filter process on the signal FLT IN [2], and the filter signal is supplied to the first inverting input terminal of the amplifier 121[2] as the reference signal REF[2].

[0069] FIG. 10 shows a configuration example of the filter 150[2]. The filter 150[2] in FIG. 10 is a primary RC filter having a resistor 151 and a capacitor 152. That is, the signal FLT is applied to the first end of the resistor 151 INWhen [2] is applied, a reference signal REF[2] as a filter signal is generated at the connection node between the second end of the resistor 151 and the first end of the capacitor 152. The second end of the capacitor 152 is connected to the ground. As long as the filter 150[2] functions as a low-pass filter, the configuration of the filter 150[2] is not limited to that shown in FIG. 10. For example, the filter 150[2] may be a second-order RC filter. An impedance conversion circuit such as a voltage follower may be provided at at least one of the front stage and the rear stage of the filter 150[2].

[0070] As described above, the switching control circuit 120[i] controls the coil current IL[i] based on the difference between the error signal EOUT and the reference signal REF[i]. The reference signal of the first channel is invariant at the reference signal REF[1], while the reference signal REF[2] of the second channel is switched between the error signal EOUT and the reference signal REF[1] by the function of the selector 140[2]. Furthermore, due to the function of the filter 150[2], the potential of the reference signal REF[2] of the second channel varies between the potential of the error signal EOUT and the potential of the reference signal REF[1].

[0071] FIG. 11 shows a timing chart when changing from "NUM = 1" to "NUM = 2". For simplicity of explanation, in the timing charts shown in FIG. 11 and FIG. 12 described later, the load current I OUT is assumed to be constant (I OUT > 0), and the ripple of each coil current IL is ignored (it is assumed that the ripple is zero). In FIG. 11, for the sake of illustration, the waveform of the error signal EOUT (solid line waveform) and the waveform of the reference signal REF[2] (dashed line waveform) before the time t A1 are shown with a slight vertical shift. Before the time t A1 "NUM = 1", and the management circuit 130 switches from "NUM = 1" to "NUM = 2" at the time t A1 . That is, the management circuit 130 sets the operating state of the DC / DC converter of the first channel and the stop state of the DC / DC converter of the second channel before the time t A1 , and at the time t A1While maintaining the DC / DC converter of the first channel in an operating state, the DC / DC converter of the second channel is switched from a stopped state to an operating state.

[0072] The management circuit 130 switches from "NUM=1" to "NUM=2" at time t A1 During the low-level period of the selection signal SEL[2], the selector 140[2] switches the error signal EOUT to the signal FLT IN [2], and during the high level period of the selection signal SEL[2], the reference signal REF[1] is IN Select as [2].

[0073] Here, time t A1 Assume that “NUM=1” has been maintained for a sufficiently long time before time t A1 Just before this, "REF[2]=FLT IN [2]=EOUT” and “IL[1]=I OUT " and "IL[2]=0". At time t A1 In the signal FLT IN [2] switches from the error signal EOUT to the reference signal REF[1], but due to the function of the filter 150[2], A1 Starting from this point, the potential of the reference signal REF[2] gradually decreases from the potential of the error signal EOUT to the potential of the reference signal REF[1].

[0074] Therefore, at time t A1 Immediately after time t, the voltage difference (EOUT-REF[2]) is small, and the switching control circuit 120[2] controls the output stage MM[2] so that a small coil current IL[2] corresponding to the small voltage difference (EOUT-REF[2]) flows. A1 As time passes, the coil current IL[2] also increases in conjunction with the increase in the voltage difference (EOUT-REF[2]). On the other hand, from time t A1 After that, the coil current IL[2] is generated by the output voltage V OUT This results in an increase in the output voltage V OUTThe increase results in a decrease in the error signal EOUT and a decrease in the coil current IL[1]. At time t A1 After that, finally, the magnitudes of the coil currents IL[1] and IL[2] converge to 1 / 2 of the load current I OUT respectively. Thus, in the switching power supply device 1A, since there is no rapid change in the coil current IL (see Fig. 5) accompanying the increase in the number of operating channels, overshoot of the output voltage V OUT hardly occurs.

[0075] Fig. 12 shows a timing chart when changing from “NUM = 2” to “NUM = 1”. In Fig. 12, for the sake of illustration, the waveform of the coil current IL[1] (solid line waveform) and the waveform of the coil current IL[2] (dotted waveform) before time t A2 are shown with a slight vertical shift. Before time t A3 it is “NUM = 2”, and the management circuit 130 switches from “NUM = 2” to “NUM = 1” at time t A3 . That is, the management circuit 130 sets the DC / DC converters of the first and second channels to the operating state before time t A3 , and at time t A3 switches the DC / DC converter of the second channel from the operating state to the stopped state while maintaining the DC / DC converter of the first channel in the operating state.

[0076] When the condition for the management circuit 130 to switch from “NUM = 2” to “NUM = 1” is satisfied, first, at time t A2 the selection signal SEL[2] is switched from the high level to the low level. As a result, at the boundary of time t A2 the signal FLT IN [2] switches from the reference signal REF[1] to the error signal EOUT.

[0077] Here, it is assumed that it has been maintained at “NUM = 2” for a sufficiently long time before time t A2 . Then, at least immediately before time t A2 , “REF[2]=FLT IN [2]=REF[1]” and “IL[1]=IL[2]=IOUT is 1 / 2”. At time t A2 is a time after time t A1 (see FIG. 11). At time t A2 the signal FLT IN [2] switches from the reference signal REF[1] to the error signal EOUT. Due to the function of the filter 150[2], starting from time t A2 the potential of the reference signal REF[2] gradually rises from the potential of the reference signal REF[1] to the potential of the error signal EOUT.

[0078] Therefore, immediately after time t A2 the voltage difference (EOUT - REF[2]) is about the same as the voltage difference (EOUT - REF[1]), and generally “IL[1] = IL[2] = I OUT / 2” holds. As time elapses from time t A2 the reference signal REF[2] rises, causing the voltage difference (EOUT - REF[2]) to gradually decrease toward zero. As a result, the coil current IL[2] also gradually decreases toward zero. On the other hand, after time t A2 the decrease in the coil current IL[2] causes a decrease in the output voltage V OUT , and the decrease in the output voltage V OUT causes an increase in the error signal EOUT and an increase in the coil current IL[1]. After time t A2 finally, the magnitude of the coil current IL[1] converges to the magnitude of the load current I OUT while the magnitude of the coil current IL[2] converges to zero. After time t A2 when the magnitude of the coil current IL[2] becomes sufficiently small, at time t A3 the management circuit 130 switches from “NUM = 2” to “NUM = 1”, that is, switches the second-channel DC / DC converter from the operating state to the stopped state.

[0079] Actually, the point in time when a predetermined waiting time Δt A2 has elapsed from time t WA can be regarded as time t A3 . Considering the characteristics of the filter 150[2], the waiting time Δt WAis preset. As a variation, at time t A2 after that, the management circuit 130 monitors the voltage difference (EOUT-REF[2]), and may switch from "NUM = 2" to "NUM = 1" when the voltage difference (EOUT-REF[2]) becomes equal to or less than a predetermined value. In this way, in the switching power supply device 1A, since there is no sudden change in the coil current IL (see FIG. 6) accompanying the decrease in the number of operating channels, the output voltage V OUT has almost no undershoot.

[0080] <<Example EX_A2>> Example EX_A2 will be described. The method shown in Example EX_A1 is applicable not only to the switching power supply device 1A of "n = 2", but also when increasing or decreasing the number of operating channels NUM from an arbitrary value to another arbitrary value. For example, in the switching power supply device 1A, "n ≧ 3" may be satisfied, and a partial configuration of the switching power supply device 1A of "n = 3" is schematically shown in FIG. 13. By adding a DC / DC converter for the third channel and a selector 140[3] and a filter 150[3] for the third channel to the switching power supply device 1A of "n = 2" (that is, the switching power supply device 1A in FIG. 7), a switching power supply device 1A of "n = 3" can be obtained. The selector 140[3] and the filter 150[3] are provided in the power control device 2 (see FIG. 1). The DC / DC converter for the third channel has a switching control circuit 120[3], an output stage MM[3], and a coil L[3]. It can also be understood that the selector 140[3] and the filter 150[3] are also included in the components of the DC / DC converter for the third channel.

[0081] The configuration and operation of the switching control circuit 120[3] are the same as those of the switching control circuit 120[1] or 120[2]. In the amplifier 121[3] provided in the switching control circuit 120[3], an error signal EOUT is input to the first non-inverting input terminal, a reference signal REF[3] is input to the first inverting input terminal, a signal I SNSN [3] is input, and a signal I SNSP [3] is input. The voltage difference (ISNSP [3]-I SNSN [3] represents the average current value of the coil current IL[3]. During the operating period of the DC / DC converter of the third channel, the switching control circuit 120[3] has a voltage difference (EOUT-REF[3]) and a voltage difference (I SNSP [3]-I SNSN [3]), and controls the coil current IL[3] so that they are equal.

[0082] As described above, the management circuit 130 can generate and output the clock signals CLK (CLK[1] to CLK[3]) for n channels and the ramp voltages VR (VR[1] to VR[3]) for n channels. In addition to the above-mentioned selection signal SEL[2], the management circuit 130 outputs a selection signal SEL[3] for controlling the state of the selector 140[3].

[0083] The selector 140[3] selects either the error signal EOUT or the reference signal REF[1] according to the selection signal SEL[3]. The selector 140[3] inputs the selected signal to the filter 150[3] as the signal FLT IN [3]. The filter 150[3] is a low-pass filter that generates a filter signal by performing low-pass filter processing on the signal FLT IN [3], and the filter signal generated by the filter 150[3] is supplied to the first inverting input terminal of the amplifier 121[3] as the reference signal REF[3]. The filter 150[3] has the same configuration as the filter 150[2].

[0084] As described above, the switching control circuit 120[i] controls the coil current IL[i] based on the difference between the error signal EOUT and the reference signal REF[i]. The reference signal of the first channel is invariant at the reference signal REF[1], while the reference signal REF[3] of the third channel can be switched between the error signal EOUT and the reference signal REF[1] by the function of the selector 140[3], similar to the second channel. Furthermore, due to the function of the filter 150[3], the potential of the reference signal REF[3] of the third channel varies between the potential of the error signal EOUT and the potential of the reference signal REF[1].

[0085] Fig. 14 shows a timing chart when changing from “NUM = 2” to “NUM = 3”. For simplicity of explanation, in the timing charts shown in Fig. 14 and Fig. 15 described later, it is assumed that the load current I OUT is constant (I OUT > 0), and the ripple of each coil current IL is ignored (it is assumed that the ripple is zero). In Fig. 14, for the sake of illustration, the waveform of the error signal EOUT (solid line waveform) and the waveform of the reference signal REF[3] (dashed line waveform) before time t A6 are shown with a slight vertical shift. Before time t A6 , “NUM = 2”, and the management circuit 130 switches from “NUM = 2” to “NUM = 3” at time t A6 . That is, the management circuit 130 sets the operating states of the DC / DC converters of the first and second channels and sets the DC / DC converter of the third channel to the stopped state before time t A6 , and switches the DC / DC converter of the third channel from the stopped state to the operating state while maintaining the operating states of the DC / DC converters of the first and second channels at time t A6 .

[0086] The management circuit 130 switches the selection signal SEL[3] from the low level to the high level at the time t A6 when switching from “NUM = 2” to “NUM = 3”. The selector 140[3] selects the error signal EOUT as the signal FLT IN [3] during the low level period of the selection signal SEL[3], and selects the reference signal REF[1] as the signal FLT IN [3] during the high level period of the selection signal SEL[3].

[0087] Here, it is assumed that “NUM = 2” is maintained for a sufficiently long time before time t A6 . Then, at least immediately before time t A6 , “REF[3] = FLT IN [3] = EOUT”, and “IL[1] = IL[2] = I OUTis " / 2” and “IL[3]=0”. At time t A6 the signal FLT IN [3] switches from the error signal EOUT to the reference signal REF[1]. However, due to the function of the filter 150[3], starting from time t A6 the potential of the reference signal REF[3] gradually decreases from the potential of the error signal EOUT to the potential of the reference signal REF[1].

[0088] Therefore, immediately after time t A6 the voltage difference (EOUT - REF[3]) is tiny, and the switching control circuit 120[3] controls the output stage MM[3] so that a tiny coil current IL[3] corresponding to the tiny voltage difference (EOUT - REF[3]) flows. As time passes from time t A6 the coil current IL[3] also increases in conjunction with the increase in the voltage difference (EOUT - REF[3]). On the other hand, after time t A6 the generation of the coil current IL[3] causes the output voltage V OUT to rise, and the rise of the output voltage V OUT causes the error signal EOUT to decrease and the coil currents IL[1] and IL[2] to decrease. After time t A6 finally, the magnitudes of the coil currents IL[1] to IL[3] converge to 1 / 3 of the load current I OUT respectively. Incidentally, when “NUM = 3”, the clock signals CLK[1] to CLK[3] are rectangular wave signals with a 120° phase shift from each other.

[0089] Fig. 15 shows a timing chart when changing from “NUM = 3” to “NUM = 2”. Incidentally, in Fig. 15, for the sake of illustration, the waveforms (solid line waveforms) of the coil currents IL[1] or IL[2] and the waveform (waveform waveform) of the coil current IL[3] before time t A7 are shown with a slight vertical shift. Before time t A8 “NUM = 3”, and the management circuit 130 switches from “NUM = 3” to “NUM = 2” at time t A8 . That is, the management circuit 130 switches at time t A8Previously, set the operating states of the DC / DC converters of the first to third channels, and at time t A8 while maintaining the operating states of the DC / DC converters of the first and second channels, switch the DC / DC converter of the third channel from the operating state to the stopped state at time t

[0090] When the condition for the management circuit 130 to switch from "NUM = 3" to "NUM = 2" is satisfied, first, at time t A7 switch the selection signal SEL[3] from the high level to the low level. As a result, at time t A7 at the boundary, the signal FLT IN [3] switches from the reference signal REF[1] to the error signal EOUT

[0091] Here, assume that it has been maintained at "NUM = 3" for a sufficiently long time before time t A7 . Then, at least immediately before time t A7 , "REF[3] = FLT IN [3] = REF[1]" and "IL[1] = IL[2] = IL[3] = I OUT / 3". Time t A7 can be understood as a time after time t A6 (see FIG. 14). At time t A7 , the signal FLT IN [3] switches from the reference signal REF[1] to the error signal EOUT. However, due to the function of the filter 150[3], starting from time t A7 , the potential of the reference signal REF[3] gradually rises from the potential of the reference signal REF[1] to the potential of the error signal EOUT

[0092] Therefore, immediately after time t A7 , the voltage difference (EOUT - REF[3]) is approximately the same as the voltage difference (EOUT - REF[1]), and generally "IL[1] = IL[2] = IL[3] = I OUT / 3" holds. At time t A7As the reference signal REF[3] rises over time from A7 , the voltage difference (EOUT - REF[3]) gradually decreases toward zero, and as a result, the coil current IL[3] also gradually decreases toward zero. On the other hand, after time t OUT , the decrease in the coil current IL[3] causes a decrease in the output voltage V OUT , and the decrease in the output voltage V A7 causes an increase in the error signal EOUT and an increase in the coil currents IL[1] and IL[2]. After time t OUT , finally, the magnitudes of the coil currents IL[1] and IL[2] each converge to 1 / 2 of the load current I A7 , and the magnitude of the coil current IL[3] converges to zero. After time t A7 , at time t A8 when the magnitude of the coil current IL[3] becomes sufficiently small, the management circuit 130 switches from "NUM = 3" to "NUM = 2", that is, switches the DC / DC converter of the third channel from the operating state to the stopped state.

[0093] Actually, it may be treated as time t A7 when a predetermined waiting time Δt WA has elapsed from. As a variation, after time t A8 , the management circuit 130 may monitor the voltage difference (EOUT - REF[3]) and switch from "NUM = 3" to "NUM = 2" when the voltage difference (EOUT - REF[3]) becomes equal to or less than a predetermined value. A7

[0094] <<Example EX_B1>> Example EX_B1 will be described. FIG. 16 is an example of the switching power supply device 1 and is a configuration diagram of the switching power supply device 1B according to Example EX_B1. The switching power supply device 1B in FIG. 16 is a modification of a part of the switching power supply device 1A in FIG. 7. The switching power supply device 1B is obtained by replacing the switching control circuit 120 of each channel in the switching power supply device 1A with the switching control circuit 220. The switching control circuit 220 of the i-th channel is referred to as the switching control circuit 220[i].

[0095] The switching control circuit 220 is a modification of a part of the switching control circuit 120 in FIG. 7. The switching control circuit 220 is obtained by replacing the amplifier 121 and the current detection circuit 125 in the switching control circuit 120 with an amplifier 221 and a current detection circuit 225. The amplifier 221, the comparator 122, the control logic 123, the gate drive circuit 124, and the current detection circuit 225 in the switching control circuit 220[i] are particularly referred to as the amplifier 221[i], the comparator 122[i], the control logic 123[i], the gate drive circuit 124[i], and the current detection circuit 225[i], respectively. In the embodiment EX_B1, it is assumed that "n = 2".

[0096] Hereinafter, the configuration and operation related to the above replacement will be described. For matters not particularly described in the embodiment EX_B1, the descriptions of the embodiment EX_A1 or EX_A2 are applicable to the embodiment EX_B1. In this application, the reference numerals "120", "121", and "125" in the descriptions of the embodiment EX_A1 or EX_A2 are appropriately read as the reference numerals "220", "221", and "225".

[0097] The amplifier 221 has a non-inverting input terminal, an inverting input terminal, and an output terminal. In the amplifier 221[i] of any channel, the error signal EOUT from the error amplifier 110 is supplied to the non-inverting input terminal, and the signal I SNS [i] from the current detection circuit 225[i] is input to the inverting input terminal. The amplifier 221[i] generates a voltage VC[i] by amplifying the difference between the error signal EOUT and the signal I SNS [i], and outputs the generated voltage VC[i] from its output terminal. In the switching control circuit 220[i], the voltage VC[i] from the amplifier 221[i] is supplied to the non-inverting input terminal of the comparator 122[i].

[0098] The current detection circuit 225[i] detects the coil current IL[i], and uses the signal I SNSGenerate and output [i]. Specifically, a reference signal REF[i] is supplied to the current detection circuit 225[i], and the current detection circuit 225[i] detects the average current value of the coil current IL[i] and outputs a signal I indicating the average current value of the coil current IL[i]. SNS [i] is output with reference to the potential of the reference signal REF[i]. The signal I SNS [i] and the reference signal REF[i] are analog voltage signals. The voltage difference (I SNS [i] - REF[i]) has a value obtained by multiplying the detected average current value of the coil current IL[i] by a positive proportionality coefficient.

[0099] The amplifier 221[i] operates such that the error signal EOUT increases the voltage VC[i] as the error signal EOUT becomes higher than the signal I SNS [i] (with reference to the state where the error signal EOUT and I SNS [i] have equal potentials), and decreases the voltage VC[i] as the error signal EOUT becomes lower than the signal I SNS [i]. Therefore, during the operating period of the DC / DC converter of the i-th channel, feedback control works to make the voltage difference between the signal EOUT and I SNS [i] zero. SNS [i] becomes zero.

[0100] That is, during the operating period of the DC / DC converter of the i-th channel, when the error signal EOUT rises based on the decrease in the output voltage V OUT and "EOUT > I SNS [i]" occurs, the output duty of the output stage MM[i] increases through the increase in the voltage VC[i], and the increase in the output duty of the output stage MM[i] increases the signal I SNS [i] through the increase in the coil current IL[i]. Conversely, during the operating period of the DC / DC converter of the i-th channel, when the error signal EOUT decreases based on the increase in the output voltage V OUT and "EOUT < I SNSWhen it becomes "[i]", the output duty of the output stage MM[i] decreases through the decrease in the voltage VC[i], and the decrease in the output duty of the output stage MM[i] decreases the signal I SNS [i] through the decrease in the coil current IL[i].

[0101] During the operation period of the DC / DC converter of the i-th channel, through the feedback control as described above, the voltage difference (EOUT - I SNS [i]) stabilizes in a state where it becomes zero. That is, during the operation period of the DC / DC converter of the first channel, the switching control circuit 220[1] makes the voltage difference (EOUT - I SNS [1]) become zero (that is, reduces the difference between the signals EOUT and I SNS [1]) by performing switching control of the output stage MM[1], thereby controlling the average current value of the coil current IL[1]. Similarly, during the operation period of the DC / DC converter of the second channel, the switching control circuit 220[2] makes the voltage difference (EOUT - I SNS [2]) become zero (that is, reduces the difference between the signals EOUT and I SNS [2]) by performing switching control of the output stage MM[2], thereby controlling the average current value of the coil current IL[2].

[0102] Since the signal I SNS [i] is generated based on the potential of the reference signal REF[i], in the DC / DC converter of the i-th channel in the operating state, the average current value of the coil current IL[i] is proportional to the voltage difference (EOUT - REF[i]) (see FIG. 9). However, as also described in the embodiment EX_A1, the reference signal REF[1] is a specific reference signal (basic signal) as a basis and has a fixed potential, while the reference signal REF[2] is a reference signal whose potential can vary.

[0103] Therefore, in the switching power supply device 1B, the timing chart when changing from "NUM = 1" to "NUM = 2" is the same as FIG. 11, and the management circuit 130 operates as shown in the embodiment EX_A1. At time t A1Immediately after the DC / DC converter of the second channel switches from the stopped state to the operating state at , since the reference signal REF[2] is substantially equal to the error signal EOUT, the voltage difference (EOUT - I SNS [2]) becomes zero when the coil current IL[2] is zero, and at this time the level of the voltage VC[2] coincides with the lower limit level of the ramp voltage VR[2]. Since the output duty of the output stage MM[2] is zero when the level of the voltage VC[2] coincides with the lower limit level of the ramp voltage VR[2], the coil current IL[2] remains zero and does not increase. As time elapses from time t A1 , the potential of the reference signal REF[2] gradually decreases from the potential of the error signal EOUT to the potential of the reference signal REF[1] (see Fig. 11).

[0104] In the process of the decrease of the reference signal REF[2], the voltage difference (EOUT - REF[2]) increases, and the coil current IL[2] increases as the voltage difference (EOUT - REF[2]) increases. On the other hand, after time t A1 , the generation of the coil current IL[2] brings about an increase in the output voltage V OUT , and the increase in the output voltage V OUT brings about a decrease in the error signal EOUT and a decrease in the coil current IL[1]. After time t A1 , finally, the magnitudes of the coil currents IL[1] and IL[2] converge to 1 / 2 of the load current I OUT respectively.

[0105] In the switching power supply device 1B, the timing chart when changing from "NUM = 2" to "NUM = 1" is the same as Fig. 12, and the management circuit 130 operates as shown in the embodiment EX_A1. Immediately after the selection signal (FLT A2 [2]) by the selector 140[2] switches from the reference signal REF[1] to the error signal EOUT at time t, since the reference signal REF[2] is substantially equal to the reference signal REF[1], the output stage MM[2] is controlled so that the coil current IL[2] (= I IN / 2) corresponding to the voltage difference (EOUT - REF[1]) = (EOUT - REF[2]) flows. At time t OUT ​A2 As time elapses from , the potential of the reference signal REF[2] gradually rises from the potential of the reference signal REF[1] to the potential of the error signal EOUT (see FIG. 12).

[0106] During the rising process of the reference signal REF[2], the voltage difference (EOUT - REF[2]) decreases, and as the voltage difference (EOUT - REF[2]) decreases, the coil current IL[2] decreases. On the other hand, at time t A2 after, the decrease in the coil current IL[2] brings about a decrease in the output voltage V OUT and the decrease in the output voltage V OUT brings about an increase in the error signal EOUT and an increase in the coil current IL[1]. At time t A2 after, finally, the magnitude of the coil current IL[1] converges to the magnitude of the load current I OUT and the magnitude of the coil current IL[2] converges to zero. At time t A2 after, at time t A3 when the magnitude of the coil current IL[2] becomes sufficiently small, the management circuit 130 switches from "NUM = 2" to "NUM = 1", that is, switches the second-channel DC / DC converter from the operating state to the stopped state.

[0107] <<Example EX_B2>> Example EX_B2 will be described. The method shown in Example EX_B1 can be applied not only to the switching power supply device 1B with "n = 2", but also when increasing or decreasing the number of operating channels NUM from any value to another arbitrary value. For example, in the switching power supply device 1B, "n = 3" may be used. Similar to the transformation of the switching power supply device 1A from "n = 2" to "n = 3" (see FIGS. 7 and 13), by adding a DC / DC converter for the third channel and a selector 140[3] and a filter 150[3] for the third channel to the switching power supply device 1B with "n = 2", a switching power supply device 1B with "n = 3" can be obtained. The DC / DC converter for the third channel has a switching control circuit 220[3], an output stage MM[3], and a coil L[3]. It can also be understood that the selector 140[3] and the filter 150[3] are also included in the components of the DC / DC converter for the third channel.

[0108] The configuration and operation of the switching control circuit 220[3] are the same as those of the switching control circuit 220[1] or 220[2]. The configuration and operation of the selector 140[3] and the filter 150[3] are the same as those of the selector 140[2] and the filter 150[2], and are as shown in Example EX_A2. In the switching power supply device 1B with "n = 3", the operation when switching from "NUM = 2" to "NUM = 3" and the operation when switching from "NUM = 3" to "NUM = 2" are also the same as those shown in Example EX_A2. In the switching power supply device 1B, "n ≧ 4" may also be used.

[0109] <<Example EX_C1>> Describe Example EX_C1. Each DC / DC converter in the above-described switching power supply devices 1A and 1B is a DC / DC converter that performs current mode control by PWM modulation. However, each of the above-described techniques performed in accordance with the change in the number of operating channels NUM may be applied to a DC / DC converter that performs current mode control by a constant on-time method. FIG. 17 is an example of the switching power supply device 1 and is a configuration diagram of the switching power supply device 1C according to Example EX_C1. Each channel's DC / DC converter in the switching power supply device 1C performs current mode control by a constant on-time method.

[0110] The switching power supply device 1C includes an error amplifier 310 and a management circuit 330 as the error amplifier 10 and the management circuit 30 in FIG. 1, and includes a switch control circuit 320 as the switch control circuit 20 in FIG. 1. The error signal EOUT in the switching power supply device 1C is generated by the error amplifier 310. In Example EX_C1, it is assumed that "n = 2".

[0111] The switch control circuit 320 in the DC / DC converter of the i-th channel is particularly referred to as the switch control circuit 320[i]. Each switch control circuit 320 includes a comparison circuit 321, a one-shot circuit 324, a gate drive circuit 325, and a ripple monitor 326. The comparison circuit 321 includes a gm amplifier 322, a comparator 323, and resistors R31 and R32. The gm amplifier is a transconductance amplifier. The comparison circuit 321, gm amplifier 322, comparator 323, one-shot circuit 324, gate drive circuit 325, ripple monitor 326, resistor R31, and resistor R32 in the switch control circuit 320[i] are particularly referred to as the comparison circuit 321[i], gm amplifier 322[i], comparator 323[i], one-shot circuit 324[i], gate drive circuit 325[i], ripple monitor 326[i], resistor R31[i], and resistor R32[i], respectively.

[0112] The switching power supply device 1C further includes a selector 140[2] and a filter 150[2]. The selector 140[2] and the filter 150[2] are provided in the power control device 2 (see FIG. 1). The selector 140[2] and the filter 150[2] can also be understood as being included in the components of the second-channel DC / DC converter.

[0113] Also, in the switching power supply device 1C, a sense resistor RSNS is inserted between the coil L and the output terminal OUT for each channel. The sense resistor RSNS of the i-th channel is referred to as the sense resistor RSNS[i]. Specifically, in the switching power supply device 1C, for any integer i, the first end of the coil L[i] is connected to the switch terminal SW[i], the first end of the sense resistor RSNS[i] is connected to the output terminal OUT, and the second end of the coil L[i] is connected to the second end of the sense resistor RSNS[i].

[0114] A voltage signal having a voltage between both ends of the sense resistor RSNS[i] is referred to as a sense signal SNS[i]. The sense signal SNS[i] has the potential of the second end of the sense resistor RSNS[i] as seen from the potential of the first end (i.e., the output terminal OUT) of the sense resistor RSNS[i]. Therefore, when the coil current IL[i] has a positive value, the sense signal SNS[i] also has a positive value. The sense signal SNS[i] is a voltage signal indicating the value of the coil current IL[i], and the value of the sense signal SNS[i] is the product of the value of the coil current IL[i] and the value of the sense resistor RSNS[i].

[0115] The error amplifier 310 compares the feedback voltage V FB with the feedback reference voltage V REF and amplifies the error between the feedback voltage V FB and the feedback reference voltage V REF to generate an error signal EOUT which is a voltage signal. The error amplifier 310 includes a transconductance amplifier gm amplifier 311 and a phase compensation circuit 312. The gm amplifier 311 has an inverting input terminal for receiving the feedback voltage V FB and a feedback reference voltage V REFIt has a non-inverting input terminal that receives [input] and an output terminal connected to wiring WRa, and an error signal EOUT occurs in wiring WRa. The gm amplifier 311 outputs a current from its output terminal to wiring WRa so that the error signal EOUT rises when " FB <V REF " holds, and draws in a current from wiring WRa to its output terminal so that the error signal EOUT falls when " FB >V REF " holds. A phase compensation circuit 312 composed of a series circuit of a resistor and a capacitor is provided between wiring WRa and ground.

[0116] The internal configuration of the switch control circuit 320 is common among a plurality of channels. Therefore, the configuration and operation of the switch control circuit 320[i], which is the switch control circuit 320 for an arbitrary channel, will be described.

[0117] The comparison circuit 321[i] determines the validity of the following formula (1) based on the voltage difference (EOUT - REF[i]) between the error signal EOUT and the reference signal REF[i], the sense signal SNS[i], and the amplitude signal RPL[i], and outputs a signal CMP[i] according to the determination result. The comparison circuit 321[i] outputs a high-level signal CMP[i] when formula (1) holds, and outputs a low-level signal CMP[i] when formula (1) does not hold. The signal CMP[i] is input to the one-shot circuit 324[i]. α is a coefficient set in the comparator 323[i], and here "α = 0.5". (EOUT - REF[i]) - RPL[i]×α > SNS[i] ···(1)

[0118] The one-shot circuit 324[i] outputs a signal SHT[i] according to the signal CMP[i]. The one-shot circuit 324[i] generally maintains the signal SHT[i] at a low level. When the level of the signal CMP[i] switches from low level to high level (i.e., when the above formula (1) holds), the one-shot circuit 324[i] performs a one-shot output operation triggered by this switching. In the one-shot output operation, the one-shot circuit 324[i] sets the signal SHT[i] to high level for a time Ton, and then returns the signal SHT[i] to low level. When the signal SHT[i] is returned from high level to low level in the one-shot output operation, if the signal CMP[i] is still maintained at high level, after a predetermined minimum off time has elapsed, the one-shot circuit 324[i] performs a one-shot output operation again. The time Ton has a predetermined fixed time. Alternatively, the time Ton may be variably set according to the input voltage V IN depending on it.

[0119] The gate drive circuit 325[i] supplies gate signals GH and GL based on the signal SHT[i] to the gates of the transistors MH and ML of the output stage MM[i], thereby switching the output stage MM[i]. The gate drive circuit 325[i] sets the output stage MM[i] to the output high state during the high level period of the signal SHT[i], and sets the output stage MM[i] to the output low state during the low level period of the signal SHT[i].

[0120] The ripple monitor 326[i] is connected to the first end and the second end of the sense resistor RSNS[i]. The ripple monitor 326[i] detects the amplitude of the coil current IL[i] based on the potential difference between the first end and the second end of the sense resistor RSNS[i], and generates an amplitude signal RPL[i] as a voltage signal representing the detected value of the amplitude of the coil current IL[i]. The ripple monitor 326[i] detects the peak value of the coil current IL[i] by sampling the voltage across both ends of the sense resistor RSNS[i] at the timing when the output stage MM[i] switches from the output high state to the output low state (or immediately before or after this timing). The ripple monitor 326[i] detects the bottom value of the coil current IL[i] by sampling the voltage across both ends of the sense resistor RSNS[i] at the timing when the output stage MM[i] switches from the output low state to the output high state (or immediately before or after this timing). The coil current IL[i] is a pulsating current that rises during the period when the output stage MM[i] is in the output high state and falls during the period when the output stage MM[i] is in the output low state. The peak value and the bottom value of the coil current IL[i] represent the maximum value and the minimum value in the fluctuation range of the coil current IL[i]. The difference between the detected peak value and the detected bottom value of the coil current IL[i] represents the detected value of the amplitude of the coil current IL[i]. The ripple monitor 326[i] generates an amplitude signal RPL[i] having the difference between the detected peak value and the detected bottom value of the coil current IL[i] as a signal value.

[0121] The internal configuration and operation of the comparison circuit 321[i] will be described. The error signal EOUT generated by the error amplifier 310 is input to the non-inverting input terminal of the gm amplifier 322[i], and the reference signal REF[i] is input to the inverting input terminal of the gm amplifier 322[i]. The reference signal REF[i] is the same signal as that shown in the other embodiments described above. The gm amplifier 322[i] has a first output terminal connected to the wiring WRb[i] and a second output terminal connected to the wiring WRc[i]. The gm amplifier 322[i] converts the difference between the error signal EOUT and the reference signal REF[i] into a differential current. The differential current is composed of the current I1[i] output from the first output terminal of the gm amplifier 322[i] and the current I2[i] output from the second output terminal of the gm amplifier 322[i]. The first end of the resistor R31[i] is connected to the wiring WRb[i], and the second end of the resistor R31[i] is connected to the output terminal OUT. The first end of the resistor R32[i] is connected to the wiring WRc[i], and the second end of the resistor R32[i] is connected to the connection node between the coil L[i] and the sense resistor RSNS[i]. Therefore, the sense signal SNS[i] is applied between the second end of the resistor R31[i] and the second end of the resistor R32[i].

[0122] When "EOUT = REF[i]" holds, the gm amplifier 322[i] sets "I1[i] = I2[i]". When "EOUT > REF[i]" holds, the gm amplifier 322[i] sets "I1[i] > I2[i]". When "EOUT < REF[i]" holds, the gm amplifier 322[i] sets "I1[i] < I2[i]". When "EOUT > REF[i]" or "EOUT < REF[i]", the larger the absolute value of the voltage difference (EOUT - REF[i]), the higher the absolute value of the difference between the currents I1[i] and I2[i]. The gm amplifier 322[i], the resistor R31[i], and the resistor R32[i] generate a differential signal ΔE[i]. The differential signal ΔE[i] has the potential of the wiring WRb[i] as seen from the potential of the wiring WRc[i]. Note that the resistors R31[i] and R32[i] have the same resistance value as each other.

[0123] A differential signal ΔE[i] and an amplitude signal RPL[i] are input to a comparator 323[i]. The comparator 323[i] compares the differential signal ΔE[i] with the amplitude signal RPL[i], and outputs a signal CMP[i] based on the comparison result. The comparator 323[i] outputs a high-level signal CMP[i] when “ΔE[i]>RPL[i]×α” holds, and outputs a low-level signal CMP[i] when “ΔE[i]<RPL[i]×α” holds. When “ΔE[i]=RPL[i]×α” holds, the signal CMP[i] has a low level or a high level. Since the differential signal ΔE[i] corresponds to “(EOUT-REF[i])-SNS[i]”, the establishment of “ΔE[i]>RPL[i]×α” is equivalent to the establishment of the above formula (1).

[0124] In the DC / DC converter of the i-th channel, due to the above-described configuration and operation, a feedback control works in which the potential of the signal ((EOUT-REF[i])-RPL[i]×α) and the potential of the sense signal SNS[i] are balanced. When the feedback control works, the sense signal SNS[i] also increases or decreases in conjunction with the increase or decrease of the voltage difference (EOUT-REF[i]). That is, the coil current IL[i] is controlled by the potential of the error signal EOUT viewed from the reference signal REF[i].

[0125] If “α = 0”, the bottom value of the coil current IL[i] is controlled by the voltage difference (EOUT-REF[i]), and the bottom value of the coil current IL[i] is proportional to the voltage difference (EOUT-REF[i]) by the above feedback control. Actually, “α = 0.5” as described above. By setting “α = 0.5”, the average current value of the coil current IL[i] (i.e., the median value between the peak value and the bottom value) is controlled by the voltage difference (EOUT-REF[i]), and the average current value of the coil current IL[i] is proportional to the voltage difference (EOUT-REF[i]) by the above feedback control. That is, the switching control circuit 320[i] controls the average current value of the coil current IL[i] by switching and controlling the output stage MM[i] based on the error signal EOUT, the reference signal REF[i], the sense signal SNS[i], and the amplitude signal RPL[i].

[0126] The management circuit 330 has the same functions as the above-described management circuit 130 and can control the operation and stop of the DC / DC converter for each channel. However, it is not necessary to generate the lamp voltage VR in the management circuit 330. Further, the management circuit 330 generates a clock signal for each channel and fixes the phase of the clock signal. As a method for fixing the phase of the clock signal, the method described in Japanese Patent Laid-Open No. 2022-113636 may be used. When the DC / DC converter of the i-th channel is in the stopped state, under the control of the management circuit 330, the above-described operation in the switching control circuit 320[i] is stopped, and the output stage MM[i] is fixed in the both-off state. Also, the selection signal SEL[2] generated by the management circuit 330 is supplied to the selector 140[2].

[0127] In the embodiment EX_C1, unless otherwise specified, the above description assumes that the DC / DC converter of each channel is in the operating state (i.e., the number of operating channels NUM is 2). When changing the number of operating channels NUM, the selector 140[2] and the filter 150[2] are provided to suppress the overshoot or undershoot as described above. The configuration and operation of the selector 140[2] and the filter 150[2] are as described above in the embodiment EX_A1 and the like. In the switching power supply device 1C of FIG. 17, the reference signal REF[1] supplied to the inverting input terminal of the gm amplifier 322[1] has a fixed potential, while the reference signal REF[2] supplied to the inverting input terminal of the gm amplifier 322[2] is a filter signal output from the filter 150[2] (a signal obtained by performing a low-pass filter process on the signal FLT IN [2]).

[0128] Therefore, in the switching power supply device 1C, the timing chart when changing from "NUM = 1" to "NUM = 2" is the same as that in FIG. 11, and the matters described above in relation to FIG. 11 are also applicable to the embodiment EX_C1. At time t A1 the operation performed by the management circuit 330 at time t A1is the same as the operation performed by the management circuit 130 (see FIG. 7). In the switching power supply device 1C, the timing chart when changing from "NUM = 2" to "NUM = 1" is the same as FIG. 12, and the matters described above in relation to FIG. 12 are also applicable to the embodiment EX_C1. At time t A2 the operation performed by the management circuit 330 at time t A2 is the same as the operation performed by the management circuit 130 at time t and at time t A3 the operation performed by the management circuit 330 at time t A3 is the same as the operation performed by the management circuit 130 at time t.

[0129] Incidentally, the sense resistor RSNS[i] is an example of an impedance element inserted on the path of the coil current IL[i] (on the path through which the coil current IL[i] flows). Based on the voltage across both ends of the impedance element of the i-th channel, the sense signal SNS[i] and the amplitude signal RPL[i] are obtained. In the i-th channel, the impedance element may be arranged at any position on the path of the coil current IL[i]. For example, in the i-th channel, the impedance element may be a sense resistor connected in series to the transistor ML between the switch terminal SW[i] and the ground, or the on-resistance of the transistor ML may be used as the impedance element.

[0130] <<Embodiment EX_C2>> Describe Embodiment EX_C2. The method shown in Embodiment EX_C1 can be applied not only to the switching power supply device 1C with "n = 2", but also when increasing or decreasing the number of operating channels NUM from any value to another arbitrary value. For example, in the switching power supply device 1C, "n = 3" may be possible. Similar to the transformation from "n = 2" to "n = 3" in the switching power supply device 1A (see FIGS. 7 and 13), by adding a DC / DC converter for the third channel to the switching power supply device 1C with "n = 2" and adding a selector 140[3] and a filter 150[3] for the third channel, a switching power supply device 1C with "n = 3" can be obtained. The DC / DC converter for the third channel has a switching control circuit 320[3], an output stage MM[3], and a coil L[3]. It can also be understood that the selector 140[3] and the filter 150[3] are also included in the components of the DC / DC converter for the third channel.

[0131] The configuration and operation of the switching control circuit 320[3] are the same as those of the switching control circuit 320[1] or 320[2]. The configuration and operation of the selector 140[3] and the filter 150[3] are the same as those of the selector 140[2] and the filter 150[2], and are as shown in Embodiment EX_A2. In the switching power supply device 1C with "n = 3", the operation when switching from "NUM = 2" to "NUM = 3" and the operation when switching from "NUM = 3" to "NUM = 2" are also the same as those shown in Embodiment EX_A2. In the switching power supply device 1C, "n ≧ 4" may also be possible.

[0132] <<Embodiment EX_D>> Describe Embodiment EX_D.

[0133] The DC / DC converter for each channel constituting the above-mentioned switching power supply device 1 is a buck-type DC / DC converter, but the DC / DC converter for each channel may also be a boost-type or buck-boost-type DC / DC converter.

[0134] Regarding any signal or voltage, the relationship between their high level and low level can be reversed from that described above, without impairing the above gist.

[0135] The type of channel of the FET (field effect transistor) shown in each embodiment is illustrative. Without impairing the above gist, the type of channel of any FET can be changed between P-channel type and N-channel type.

[0136] Unless there is an inconvenience, any of the above transistors can be any type of transistor. For example, any transistor described as a MOSFET can be replaced with a junction FET, an IGBT (Insulated Gate Bipolar Transistor), or a bipolar transistor, unless there is an inconvenience. Any transistor has a first electrode, a second electrode, and a control electrode. In an FET, one of the first and second electrodes is a drain and the other is a source, and the control electrode is a gate. In an IGBT, one of the first and second electrodes is a collector and the other is an emitter, and the control electrode is a gate. In a bipolar transistor that does not belong to an IGBT, one of the first and second electrodes is a collector and the other is an emitter, and the control electrode is a base.

[0137] The embodiments of the present disclosure can be appropriately modified in various ways within the scope of the technical idea shown in the claims. The above embodiments are merely examples of the embodiments of the present disclosure, and the meaning of the terms of the present disclosure or each constituent element is not limited to those described in the above embodiments. The specific numerical values shown in the above description are merely illustrative, and of course, they can be changed to various numerical values.

[0138] <<Supplementary Note>> A supplementary note is provided for the present disclosure in which specific configuration examples were shown in the above embodiments.

[0139] A switching power supply device according to an aspect of the present disclosure includes a plurality of channels of DC / DC converters each having a coil (L), and one or more channel coil currents (IL[i]) based on an input voltage (V IN ) generate an output voltage (V OUT ). The switching power supply device (1) is configured such that an error amplifier (10) generates an error signal (EOUT) based on an error between a feedback voltage (V FB ) corresponding to the output voltage and a feedback reference voltage (V REF ). The error amplifier is shared among the plurality of channels. In each channel's DC / DC converter, based on the difference between the error signal and a reference signal (REF[1]) and the detection result of the corresponding coil current (see FIG. 7 or FIG. 17), or based on the difference between the error signal and a current detection signal (I SNS [i]) that is a signal indicating the detection result of the corresponding coil current and is generated based on the potential of the reference signal (see FIG. 16), the corresponding coil current is controlled. In the DC / DC converter of the reference channel among the plurality of channels, the reference signal is a basic signal. In the DC / DC converters of other channels among the plurality of channels, a selector (140) that switches the reference signal between the error signal and the basic signal is provided (first configuration).

[0140] Thereby, when operating the DC / DC converter of the reference channel and switching the DC / DC converter of another channel from the stopped state to the operating state, the reference signal for the DC / DC converter of the other channel can be controlled to a signal level suitable for suppressing overshoot of the output voltage. Alternatively, when operating the DC / DC converter of the reference channel and switching the DC / DC converter of another channel from the operating state to the stopped state, the reference signal for the DC / DC converter of the other channel can be controlled to a signal level suitable for suppressing undershoot of the output voltage.

[0141] In the switching power supply device according to the first configuration, a filter (150) is provided, the selector selects either the error signal or the basic signal, and the filter performs a low-pass filter process on the selection signal (FLT IN [i]) selected by the selector to generate a filter signal. In the DC / DC converter of the other channel, a configuration (second configuration) in which the filter signal is used as the reference signal may be employed.

[0142] Thereby, while operating the DC / DC converter of the reference channel, when switching the DC / DC converter of the other channel from the stopped state to the operating state, the potential of the reference signal for the DC / DC converter of the other channel can be gradually changed between the error signal and the basic signal, whereby overshoot of the output voltage can be suppressed. Alternatively, while operating the DC / DC converter of the reference channel, when switching the DC / DC converter of the other channel from the operating state to the stopped state, the potential of the reference signal for the DC / DC converter of the other channel can be gradually changed between the error signal and the basic signal, whereby overshoot of the output voltage can be suppressed.

[0143] In the switching power supply device according to the second configuration, a management circuit (30) configured to control the operation or stop of the DC / DC converter of each channel and to control the state of the selector is provided. The management circuit sets the selection signal by the selector to the error signal during a period in which the DC / DC converter of the other channel is maintained in the stopped state, and then switches the selection signal by the selector from the error signal to the basic signal when switching the DC / DC converter of the other channel from the stopped state to the operating state during the operation period of the DC / DC converter of the reference channel. A configuration (third configuration) may be employed.

[0144] Thereby, when switching the DC / DC converter of the other channel from the stopped state to the operating state, overshoot of the output voltage is suppressed.

[0145] In the switching power supply device according to the second configuration, a management circuit (30) is provided that controls the operation or stop of the DC / DC converters of each channel and controls the state of the selector. The management circuit sets the selection signal by the selector to the basic signal during a period in which the DC / DC converters of the other channels are maintained in an operating state, and then, when switching the DC / DC converter of the reference channel from an operating state to a stopped state, after switching the selection signal by the selector from the basic signal to the error signal and after a predetermined time has elapsed, the DC / DC converter of the other channels is switched to the stopped state (a fourth configuration).

[0146] Thereby, undershoot of the output voltage is suppressed when switching the DC / DC converter of another channel from an operating state to a stopped state.

[0147] In the switching power supply device according to any one of the first to fourth configurations, the DC / DC converter of each channel has an output stage (MM) for power-converting the input voltage to the output voltage using a corresponding coil, and a switching control circuit (20) configured to perform switching control of the output stage. In the DC / DC converter of each channel, the switching control circuit controls the corresponding coil current by performing switching control of the output stage based on the difference between the error signal and the reference signal and the detection result of the corresponding coil current, or based on the difference between the error signal and the current detection signal (a fifth configuration).

[0148] Regarding the switching power supply device according to the fifth configuration, in the DC / DC converter of each channel, the switching control circuit may be configured to make the corresponding coil current proportional to the difference between the error signal and the reference signal (a sixth configuration).

[0149] Regarding the switching power supply device (1A; see FIG. 7) according to the above-described fifth or sixth configuration, in the DC / DC converter of each channel, the switching control circuit (120[i]) uses the error signal (EOUT), the reference signal (REF[i]), and a signal (I SNSP [i]-I SNSN [i]) indicating the average current value of the corresponding coil current to perform switching control on the output stage, thereby controlling the average current value of the corresponding coil current (seventh configuration).

[0150] Regarding the switching power supply device according to the above-described seventh configuration, in the DC / DC converter of each channel, the signal indicating the average current value of the corresponding coil current is a differential signal composed of a first signal (I SNSP [i]) and a second signal (I SNSN [i]). The difference between the first signal and the second signal indicates the average current value of the corresponding coil current. In the DC / DC converter of each channel, the switching control circuit uses the difference between the error signal and the reference signal (EOUT - REF[i]) and the difference between the first signal and the second signal (I SNSP [i]-I SNSN [i]) to perform switching control on the output stage so as to reduce the error therebetween (eighth configuration).

[0151] Regarding the switching power supply device (1B; see FIG. 16) according to the above-described fifth or sixth configuration, in the DC / DC converter of each channel, the switching control circuit (220[i]) has a current detection circuit (225[i]) configured to generate a signal indicating the average current value of the corresponding coil current as the current detection signal (I SNS [i]) based on the potential of the reference signal, and performs switching control on the output stage based on the error signal and the current detection signal, thereby controlling the average current value of the corresponding coil current (ninth configuration).

[0152] Regarding the switching power supply device according to the ninth configuration, in the DC / DC converter of each channel, the switching control circuit reduces the difference (EOUT - I SNS [i]) between the error signal and the current detection signal, and may be configured to perform switching control on the output stage (tenth configuration).

[0153] Regarding the switching power supply device (1C; see FIG. 17) according to the fifth or sixth configuration, in the DC / DC converter of each channel, the switching control circuit (320[i]) is based on the error signal (EOUT), the reference signal (REF[i]), the sense signal (SNS[i]) indicating the value of the corresponding coil current, and the amplitude signal (RPL[i]) indicating the amplitude of the corresponding coil current, and may be configured to perform switching control on the output stage to control the average current value of the corresponding coil current (eleventh configuration).

[0154] Regarding the switching power supply device according to the eleventh configuration, in the DC / DC converter of each channel, the switching control circuit includes a gm amplifier (322[i]) configured to convert the difference between the error signal and the reference signal into a differential current composed of a first current and a second current, a first output terminal from which the first current in the gm amplifier is output, a first resistor (R31[i]) provided between the first output terminal and the first end of an impedance element (RSNS[i]) provided on the path of the corresponding coil current, a second resistor (R32[i]) provided between the second output terminal from which the second current in the gm amplifier is output and the second end of the impedance element, and based on the differential signal (ΔE[i]) between the first output terminal and the second output terminal of the gm amplifier and the amplitude signal (RPL[i]), may be configured to perform switching control on the output stage (twelfth configuration).

[0155] Regarding the switching power supply device according to any one of the above-described fifth to twelfth configurations, in the DC / DC converter of each channel, the output stage has a series circuit of a high-side transistor (MH) and a low-side transistor (ML), and a corresponding coil is provided between the connection node between the high-side transistor and the low-side transistor and the terminal where the output voltage is generated. The switching control circuit may be configured to alternately turn on and off the high-side transistor and the low-side transistor by the switching control of the output stage (the thirteenth configuration).

Explanation of Signs

[0156] 1 Switching power supply device 2 Power control device 10 Error amplifier 20, 20[i] Switching control circuit 30 Management circuit MM, MM[i] Output stage MH High-side transistor ML Low-side transistor L, L[i] Coil C OUT Output capacitor R1, R2 Feedback resistor LD Load IN Input terminal SW, SW[i] Switch terminal GND Ground terminal V IN Input voltage V OUT Output voltage V FB Feedback voltage V REF Feedback reference voltage IL, IL[i] Coil current I OUT Load current VS Voltage source EOUT Error signal 1A Switching power supply device 110 Error amplifier 120[i] Switching control circuit 121[i] Amplifier 122[i] Comparator 123[i] Control Logic 124[i] Gate Drive Circuit 125[i] Current Detection Circuit 130 Management Circuit 140[i] Selector 150[i] Filter 151 Resistor 152 Capacitor CLK[i] Clock Signal VR[i] Lamp Voltage SEL[i] Selection Signal REF[i] Reference Signal 1B Switching Power Supply 220[i] Switching Control Circuit 221[i] Amplifier 225[i] Current Detection Circuit 1C Switching Power Supply 310 Error Amplifier 311 gm Amplifier 312 Phase Compensation Circuit 320[i] Switching Control Circuit 321[i] Comparison Circuit 322[i] gm Amplifier 323[i] Comparator 324[i] One-Shot Circuit 325[i] Gate Drive Circuit 326[i] Ripple Monitor R31[i], R32[i] Resistor RSNS[i] Sense Resistor 330 Management Circuit ΔE[i] Differential Signal SNS[i] Sense Signal RPL[i] Ripple Signal

Claims

1. A switching power supply device comprising a plurality of channels of DC / DC converters each having a coil, and configured to generate an output voltage by the coil current of one or more channels based on an input voltage, comprising an error amplifier configured to generate an error signal based on an error between a feedback voltage corresponding to the output voltage and a feedback reference voltage, and sharing the error amplifier among the plurality of channels, in the DC / DC converter of each channel, based on the difference between the error signal and a reference signal and the detection result of the corresponding coil current, or controlling the corresponding coil current based on the difference between the error signal and a current detection signal indicating the detection result of the corresponding coil current and generated based on the potential of the reference signal, in the DC / DC converter of the reference channel among the plurality of channels, the reference signal is a basic signal, in the DC / DC converters of the other channels among the plurality of channels, a selector is provided for switching the reference signal between the error signal and the basic signal , a switching power supply device.

2. Comprising a filter, the selector selects either the error signal or the basic signal, the filter generates a filtered signal by performing low-pass filter processing on the selection signal by the selector, in the DC / DC converter of the other channels, the filtered signal is used as the reference signal , the switching power supply device according to claim 1.

3. Comprising a management circuit configured to control the operation or stop of the DC / DC converter of each channel and to control the state of the selector, the management circuit sets the selection signal by the selector to the error signal during a period in which the DC / DC converters of the other channels are maintained in a stopped state, and then, when switching the DC / DC converters of the other channels from a stopped state to an operating state during the operating period of the DC / DC converter of the reference channel, switches the selection signal by the selector from the error signal to the basic signal , the switching power supply device according to claim 2.

4. Comprising a management circuit configured to control the operation or stop of the DC / DC converter of each channel and to control the state of the selector, The management circuit sets the selection signal by the selector to the basic signal during the period in which the DC / DC converter of the other channel is maintained in the operating state, and then, when switching the DC / DC converter of the other channel from the operating state to the stopped state during the operating period of the DC / DC converter of the reference channel, after switching the selection signal by the selector to the error signal from the basic signal and after a predetermined time has elapsed, switches the DC / DC converter of the other channel to the stopped state. The switching power supply device according to claim 2.

5. The DC / DC converter of each channel has an output stage for power-converting the input voltage to the output voltage using a corresponding coil, and a switching control circuit configured to perform switching control of the output stage. In the DC / DC converter of each channel, the switching control circuit controls the corresponding coil current by performing switching control of the output stage based on the difference between the error signal and the reference signal and the detection result of the corresponding coil current, or based on the difference between the error signal and the current detection signal. The switching power supply device according to any one of claims 1 to 4.

6. In the DC / DC converter of each channel, the switching control circuit makes the corresponding coil current proportional to the difference between the error signal and the reference signal. The switching power supply device according to claim 5.

7. In the DC / DC converter of each channel, the switching control circuit controls the average current value of the corresponding coil current by performing switching control of the output stage based on the error signal, the reference signal, and a signal indicating the average current value of the corresponding coil current. The switching power supply device according to claim 5.

8. In the DC / DC converter of each channel, the signal indicating the average current value of the corresponding coil current is a differential signal composed of a first signal and a second signal, and the average current value of the corresponding coil current is indicated by the difference between the first signal and the second signal. In the DC / DC converter of each channel, the switching control circuit performs switching control of the output stage so as to reduce the error between the difference between the error signal and the reference signal and the difference between the first signal and the second signal. The switching power supply device according to claim 7.

9. In the DC / DC converter of each channel, the switching control circuit has a current detection circuit configured to generate, as the current detection signal, a signal indicating an average current value of a corresponding coil current with reference to the potential of the reference signal, and controls the average current value of the corresponding coil current by performing switching control on the output stage based on the error signal and the current detection signal. The switching power supply device according to claim 5.

10. In the DC / DC converter of each channel, the switching control circuit performs switching control on the output stage so as to reduce the difference between the error signal and the current detection signal. The switching power supply device according to claim 9.

11. In the DC / DC converter of each channel, the switching control circuit controls the average current value of the corresponding coil current by performing switching control on the output stage based on the error signal, the reference signal, a sense signal indicating the value of the corresponding coil current, and an amplitude signal indicating the amplitude of the corresponding coil current. The switching power supply device according to claim 5.

12. In the DC / DC converter of each channel, the switching control circuit includes a gm amplifier configured to convert the difference between the error signal and the reference signal into a differential current composed of a first current and a second current, a first resistor provided between a first output terminal from which the first current in the gm amplifier is output and a first end of an impedance element provided on a path of the corresponding coil current, a second resistor provided between a second output terminal from which the second current in the gm amplifier is output and a second end of the impedance element, and performs switching control on the output stage based on a differential signal between the first output terminal and the second output terminal of the gm amplifier and the amplitude signal. The switching power supply device according to claim 11.

13. In the DC / DC converter of each channel, the output stage has a series circuit of a high-side transistor and a low-side transistor, a corresponding coil is provided between a connection node between the high-side transistor and the low-side transistor and a terminal where the output voltage is generated, and the switching control circuit alternately turns on and off the high-side transistor and the low-side transistor by performing switching control on the output stage. The switching power supply device according to claim 5.

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