JP2013172468A - Switching power circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power circuit that is a single-inductor multiple-output DC/DC conversion circuit and that can reduce the influence from a cross regulation.SOLUTION: A switching power circuit of the present invention controls each output voltage of a single-inductor multiple-output DC/DC conversion circuit, the switching power circuit comprising: a single-inductor multiple-output DC/DC conversion circuit for converting an input voltage to a plurality of output voltages, the conversion circuit having a plurality of channels to obtain one voltage for each channel; and a control circuit that selects a channel having a greatest error between an output voltage and a prescribed voltage at each channel of the single-inductor multiple-output DC/DC conversion circuit for each switching cycle during the switching to obtain the one output voltage, the control circuit performing the switching to obtain the output voltage without changing the total time of the control cycle for each channel but changing the control cycle of the output voltage.

Description

  The present invention relates to a switching power supply circuit, and more particularly to a switching power supply circuit in a single-inductor multi-output power supply in which the output voltage ripple at the time of load response is reduced and the influence of cross regulation is reduced.

  In recent years, electronic devices have been improved in size and functionality in spite of their small size. The power supplies of these electronic devices have high output voltage stability and high-speed load against disturbances such as input voltage fluctuation and load fluctuation. High performance such as response characteristics is required.

  In addition, when a DC input device such as a personal computer is used from a household power source using an AC / DC power supply, AC rectification is performed from the AC power source using a smoothing circuit, but only an unstable DC current can be obtained. It is necessary to obtain a stable direct current using a DC / DC converter. For this purpose, a DC / DC converter for generating a driving voltage for each IC is incorporated in the DC input device. The required performance of these DC / DC converters includes high efficiency and fast transient response. In order to meet these requirements, the control unit of the DC / DC converter must improve. Further, the DC / DC converter is required to be downsized and reduced in cost. For that purpose, it is necessary to improve from the power stage of the DC / DC converter.

  As a conventionally known switching power supply device, there is a DC / DC converter by PWM control. This DC / DC converter by PWM control includes a switching element and an inductor for stepping down or boosting an input voltage as a power stage, and controls on / off of the switching element by a PWM signal whose pulse width is proportional to the input signal as a control unit. A PWM modulator is provided.

  In recent years, electronic devices such as mobile phones have become more multifunctional, and many electronic components are mounted on one electronic device. In addition, there is a demand for downsizing of electronic devices, and electronic devices driven by a single battery are becoming popular.

  By the way, since each electronic component in an electronic device has a different power supply voltage for driving, in order to supply power with a single battery, the power supply voltage for driving each electronic component from the voltage of a single battery The DC / DC converter that generates the voltage is required for each electronic component. However, preparing a DC / DC converter for each electronic component has the problem of increasing the number of components. Therefore, instead of preparing a DC / DC converter for each electronic component, there is known a multi-output power supply device that shares an inductor, that is, is configured with a single inductor and generates a plurality of power supply voltages (for example, , See Patent Document 1).

  The DC / DC converter has a property of correcting the output voltage by changing the pulse width of the PWM signal in accordance with the change in the output voltage of the power supply. By designing the power supply by taking advantage of this feature, the change in the pulse width of the PWM signal of the switching power supply becomes small in the steady state where the output state of the switching power supply is small. On the other hand, the pulse width of the PWM signal becomes large in a transient state where the load current changes greatly and the output of the power supply changes. Furthermore, in a transient state, it is possible to perform an operation that enables a high-speed response to a sudden change in the output voltage by increasing the switching frequency of the switching power supply.

  FIGS. 1A and 1B are configuration circuit diagrams showing a conventional multi-output DC / DC converter. FIG. 1A is a configuration circuit diagram of a multi-output DC / DC converter, and FIG. 1B is a specific circuit configuration diagram of the control circuit shown in FIG. FIGS. 1A and 1B are described in Patent Document 2, and are a multi-output DC / DC converter using a single inductor and PWM control.

  The multi-output DC / DC converter shown in FIG. 1A is connected to an input DC power supply 1 and receives an input DC voltage Ei. This multi-output DC / DC converter includes an N-channel MOSFET first main switch 21, a P-channel MOSFET second main switch 22, an inductor 31, a diode first rectifier 51, and a capacitor first smoothing. Means 61, diode second rectification means 52, and capacitor second smoothing means 62 are provided. Further, a control circuit 81 is provided for driving the first main switch 21 and the second main switch 22 in a predetermined on period and off period, respectively. A first load 71 is connected to both ends of the first smoothing means 61, and a boosted output voltage Vo <b> 1 is output to the first load 71. A second load 72 is connected to both ends of the second smoothing means 62, and an inverted output voltage Vo <b> 2 is output to the second load 72. The input / output conditions are Vo1> Ei> 0> Vo2. When the second main switch 22 is in the ON state, the first main switch 21, the inductor 31, the first rectifying means 51, and the first smoothing means 61 operate as a boost converter. On the other hand, when the first main switch 21 is in the ON state, the second main switch 22, the inductor 31, the second rectifying means 52, and the second smoothing means 62 operate as an inverting converter.

  In FIG. 1B, a resistor 801 and a resistor 802 detect a boosted output voltage Vo1, and a resistor 803 and a resistor 804 detect an inverted output voltage Vo2. Each detected voltage is compared with the reference voltage of the reference voltage source 807 by the error amplifier 805 and the error amplifier 806, respectively, and a boost output error signal Ve1 and an inverted output error signal Ve2 are output. The resistors 801 to 804, the error amplifier 805, the error amplifier 806, and the reference voltage source 807 constitute a detection circuit 90. The oscillation circuit 808 outputs a triangular wave voltage Vt whose potential increases or decreases in a predetermined cycle, and a signal Vt1 which becomes “H” when the triangular wave voltage Vt increases and becomes “L” when it decreases. The comparator 809 compares the boost output error signal Ve1 and the triangular wave voltage Vt. The comparator 810 compares the inverted output error signal Ve2 with the triangular wave voltage Vt. The output signals of the comparators 809 and 810 are output as AND signals 811 and 812, respectively, as a signal V1 and a signal V2 indicating a logical product with the signal Vt1. Here, the signal V1 is a boost output pulse signal, and the signal V2 is an inverted output pulse signal. The comparators 809 and 810 and the AND circuits 811 and 812 constitute a PWM circuit 91. A signal Vt1 is input to a T flip-flop 813 which is a frequency dividing circuit, and a signal Vt2 is output. The OR circuit 814 receives the signal V1 and the signal Vt2, and outputs a drive signal Vg21. The drive signal Vg21 drives the first main switch 21, which is an N-channel MOSFET, and turns on the first main switch 21 with "H". The NOR circuit 815 receives the signal V2 and the inverted signal of the signal Vt2, and outputs a drive signal Vg22. The drive signal Vg22 drives the second main switch 22 which is a P-channel MOSFET, and turns on the second main switch 22 with “L”. The drive signal Vg21 and the drive signal Vg22 are main switch drive signals. The OR circuit 814 and the NOR circuit 815 constitute a logic circuit 92.

  Non-Patent Documents 1 and 2 describe single inductor positive / negative two-output DC / DC converters.

JP 2003-164143 A

IEICE paper “Study of single-inductor positive-negative two-output DC-DC converter using quasi-continuous mode” (Kenji Tsushida et al. 8th 22nd Circuit and System (Karuizawa) Workshop) The 22nd Circuit and System Karuizawa Workshop "Study of Single Inductance 2 Output DC-DC Converter" (Tenshi Kenji et al., 13 people 4.19-20, 2010)

  In a multi-output DC / DC converter that controls the boosting operation of power supplies of n channels (n is an integer of 2 or more) evenly in a time-sharing manner, the load current at the output terminal of one channel greatly changes and the output voltage When the voltage fluctuates, there is a problem that a long time is required until the output voltage of the channel is stabilized, and the output voltage ripple becomes large. Generally, in a single output DC / DC converter, it takes 10 switching cycles or more to stabilize after a large change in load current. In a multi-output DC / DC converter having n channels, n times as much time is required, and the output voltage ripple becomes large. When switching from the output voltage step-up / step-down operation of one output terminal to the output voltage step-up / step-down operation of the other output terminal, the charging current charged in the inductor during the previous step-up / step-down operation leaks to the other output terminal There is. That is, there is a problem that the charging current to be transferred to one output terminal is greatly influenced by cross regulation in which the output voltage is transferred to another output terminal and the output voltage fluctuates.

  The present invention has been made in view of such problems, and its object is to reduce the output voltage ripple at the time of load fluctuation and to reduce the influence of cross regulation so as to reduce the influence of cross regulation. The object is to provide a switching power supply circuit which is a DC / DC conversion circuit.

  The present invention has been made in order to achieve such an object. The object of the present invention is to reduce the output voltage ripple at the time of load fluctuation and to reduce the influence of cross regulation. An object of the present invention is to provide a switching power supply circuit which is a multi-output DC / DC conversion circuit.

  The switching power supply circuit of the present invention for controlling each output voltage of a single inductor multiple output DC / DC conversion circuit is a single inductor multiple output DC / DC conversion circuit for converting an input voltage into a plurality of output voltages, The single inductor multi-output DC / DC conversion circuit has a plurality of channels, and from each channel of the plurality of channels, a single output voltage is obtained by performing time-sharing of the inductor and performing switching. Inductor multi-output DC / DC converter circuit and output voltage value and desired voltage in each channel of the single inductor multi-output DC / DC converter circuit for each switching cycle of the switching to obtain the one output voltage The channel with the largest error is selected, and the total control period of each channel is not changed, and the output voltage of the selected channel is not changed. The control cycle of the output voltage in the channel that does not select the control cycle is changed relatively large, and the control cycle of the output voltage in the channel that is not selected is changed relatively small relative to the control cycle of the output voltage in the selected channel. And a control circuit that obtains an output voltage for each channel by performing the switching control and controls each output voltage of the single inductor multi-output power supply circuit.

  The single inductor multi-output DC / DC conversion circuit of the present invention includes an error amplifier that outputs an error between the output voltage and the desired voltage in each channel, and the control circuit includes the channel in each channel. Compare the output of the error amplifier, select a channel with a large output of the error amplifier among the channels, and control the output voltage in the selected channel without changing the total time of the control period of each channel Change the output voltage control period in the non-selected channel relatively large, and change the output voltage control period in the non-selected channel relatively small relative to the output voltage control period in the selected channel. For each of the channels, an output voltage is obtained by performing the switching control, and the single inductor is obtained. And wherein performing the control of the output voltages of the data multi-output power supply circuit.

  The switching power supply circuit of the present invention for controlling each output voltage of a single inductor multiple output DC / DC conversion circuit is a single inductor multiple output DC / DC conversion circuit for converting an input voltage into a plurality of output voltages, The single inductor multi-output DC / DC conversion circuit has a plurality of channels, and each channel of the plurality of channels obtains one output voltage by switching the inductor in a time-sharing manner. One inductor multi-output DC / DC converter circuit, and an output voltage and a desired voltage in each channel of the single inductor multi-output DC / DC converter circuit for each switching cycle of the switching to obtain the one output voltage A channel other than the one with the largest error is selected, and the selected channel is not changed without changing the switching cycle of each channel. The output voltage control period of the single inductor multi-output power supply circuit is obtained by reducing the control cycle of the output voltage relative to the switching cycle and performing the switching for each channel. And a control circuit for performing control.

  The single inductor multi-output DC / DC conversion circuit of the present invention includes an error amplifier that outputs an error between the output voltage and the desired voltage in each channel, and the control circuit includes the channel in each channel. Compare the output of the error amplifier, select a channel other than the channel with the largest output of the error amplifier among the channels, and change the total time of the control period of each channel without changing the total time of the control cycle of each channel. The output voltage control period is made relatively small with respect to a channel not selected, and the output voltage is obtained by performing the switching control for each channel, and the output voltage of each single inductor multi-output power supply circuit is obtained. Control is performed.

  According to the present invention, it is possible to control the control period or control cycle of the power supply of each channel according to the load fluctuation of each channel, and to shorten the time until the output voltage is stabilized. The voltage ripple can be reduced and the influence of cross regulation can be reduced.

It is a circuit diagram showing a conventional multi-output DC / DC converter. (A) is a circuit diagram of the multi-output DC / DC converter, and (b) is a specific circuit diagram of the control circuit shown in (a). FIG. 2 is a block diagram of a configuration of a switching power supply circuit using PWM control that has been conventionally used, where (a) is an overall configuration diagram of the switching power supply circuit, and (b) is a relationship between a sawtooth wave and an output of an error amplifier (error amplifier) FIG. 3C is a diagram showing an output signal of the PWM circuit. 2A and 2B are diagrams for explaining a single inductor two-output DC / DC conversion circuit, in which FIG. 1A shows a conventional two-output DC / DC conversion circuit, and FIG. 2B shows a single inductor two-output DC / DC conversion circuit. is there. FIG. 2 is a principle diagram of a single inductor two-output DC / DC conversion circuit, where (a) is a circuit configuration diagram of a two-output boost converter, and (b) is a diagram illustrating a current waveform of the inductor. It is a figure for demonstrating the cross regulation in a multi-output DC / DC conversion circuit. It is a circuit block diagram for demonstrating the switching power supply circuit provided with the multiple output DC / DC conversion circuit which concerns on this invention. FIG. 7 shows an inductor current when a method for shortening the PWM period of any one of the power supplies at the start of the clock in the switching power supply circuit having the single inductor 2-output DC / DC conversion circuit according to the present invention of FIG. It is a figure which shows these waveforms. FIG. 8 shows a case where the switching power supply circuit having the single inductor 2 output DC / DC conversion circuit according to the present invention shown in FIG. 6 is controlled by changing the control duty of the two power supplies at the start of the clock. It is a figure which shows the waveform of inductor current. FIG. 7 is a specific circuit configuration diagram of the switch control circuit in FIG. 6, (a) is a conceptual diagram for operating each switch in response to outputs of a control ratio generator and a differential amplifier, and (b) is a circuit configuration of the switch control circuit FIG. 4C is a diagram showing a truth table. It is a figure for demonstrating the switching power supply circuit provided with the single inductor 2 output DC / DC conversion circuit which concerns on this invention, and is a circuit block diagram from the error amplifier of each channel to a switch control circuit. It is the figure which showed the waveform of each node in the circuit shown in FIG.

  Before describing an embodiment of a switching power supply circuit according to the present invention, a switching power supply circuit based on PWM control will be described first.

  2A and 2B are diagrams for explaining a switching power supply circuit by PWM control. FIG. 2A is an overall configuration diagram of the switching power supply circuit, and FIG. 2B is a sawtooth wave. It is a figure which shows the relationship with an error amplifier (amplification error device).

  In FIG. 2A, when an input voltage is input to a DC / DC conversion circuit (DC / DC converter) 101, the input voltage is stepped up or down to output an output voltage. The output voltage is input to the error amplifier 102, and an error signal corresponding to the error from the reference voltage Vref is output to the PWM circuit 105. Then, the comparator 103 constituting the PWM circuit 105 compares the sawtooth wave from the sawtooth wave generating circuit 104 with the error signal from the error amplifier 102. Here, the relationship between the sawtooth wave and the output of the error amplifier is, for example, as shown in FIG. That is, one cycle of the sawtooth wave is one switching cycle, and the error signal of the error amplifier 102 changes every switching cycle, and the output signal of the PWM circuit 105 has a different pulse width as shown in FIG. A signal is output. Here, the pulse width corresponds to an error from the desired output voltage of the output voltage of the switching power supply circuit. A switching operation corresponding to the pulse width is performed in the DC / DC conversion circuit 101 via the switch control circuit 106, and an output voltage obtained by stepping up or down the input voltage is obtained as the output voltage of the switching power supply circuit.

  Next, the multi-output DC / DC conversion circuit will be described below.

  3A and 3B are diagrams for explaining a single inductor two-output DC / DC conversion circuit. FIG. 3A shows a conventional two-output DC / DC conversion circuit, and FIG. These show the single inductor 2 output DC / DC conversion circuit.

  The conventional two-output DC / DC conversion circuits 111a and 111b require two inductors L, and are large in size and cost. On the other hand, the single inductor 2 output DC / DC conversion circuit 112 has one inductor L, and is small in size and cost.

  As shown in FIG. 3A, each electronic component in an electronic device has a different power supply voltage for driving. Therefore, in order to supply power with a single battery, each electronic component is derived from the voltage of a single battery. A DC / DC conversion circuit that generates a power supply voltage for driving the components is required for each electronic component. However, preparing a DC / DC conversion circuit for each electronic component has a problem of increasing the number of components. Therefore, instead of preparing a DC / DC conversion circuit for each electronic component, as shown in FIG. 3B, the inductor is shared, that is, a single inductor is used to generate a plurality of power supply voltages. An output power supply is required. That is, a single inductor multiple output (SIMO (Single Inductor, Multiple Output)) DC / DC conversion circuit is useful.

  4A and 4B are principle diagrams of a single inductor 2-output DC / DC conversion circuit, and FIG. 4A is a circuit configuration diagram of the single inductor 2-output DC / DC conversion circuit. (B) shows the inductor current waveform.

  The single inductor two-output DC / DC conversion circuit 121 has two channels, and a first output voltage Vo1 is obtained from the first channel, and constitutes a first power supply. A second output voltage Vo2 is obtained from the second channel, and constitutes a second power supply.

  First, the first channel includes a power supply E that receives an input voltage Vin, an inductor L, switches SW0 and SW1, and a capacitor C1. Here, one end of the inductor L is connected to the positive side of the power source E, and the other end is connected to the switches SW0 and SW1. One end of the switch SW0 is grounded. The switch SW1 is connected to one end of the capacitor C1 and the resistor R1, and constitutes a first power supply that obtains the first output voltage Vo1. The other ends of the capacitor C1 and the resistor R1 are each grounded. Further, both ends of the capacitor C1 are connected to a load R1 such as an electronic device.

  Next, the second channel includes a power supply E for inputting the input voltage Vin, an inductor L, switches SW0 and SW2, and a capacitor C2. Here, one end of the inductor L is connected to the plus side of the power source E, and the other end is connected to the switches SW0 and SW2. One end of the switch SW0 is grounded. The switch SW2 is connected to one end of the capacitor C2 and the resistor R2, and constitutes a second power source that obtains the second output voltage Vo2. The other ends of the capacitor C2 and the resistor R2 are each grounded. Further, both ends of the capacitor C2 are connected to a load R2 such as an electronic device.

Next, the operation of the single inductor 2-output DC / DC conversion circuit 121 shown in FIG. Illustrates the waveform of the charging current I _L flowing through the inductor L in this case in Figure 4 (b). The illustrated waveform is a waveform when the switches SW0 to SW2 are switched by a PWM signal, and is a waveform in a stable steady state.

  In order to obtain two output voltages Vo1 and Vo2, the single inductor 2-output DC / DC conversion circuit 121 is provided with two switching cycles for charging the capacitors C1 and C2, and uses the inductor in a time-sharing manner. By doing so, charge. That is, in the first cycle (first switching cycle) of the two periods, the boost operation for obtaining the first output voltage Vo1 is performed, and the second cycle (second cycle) of the two periods is performed. In the switching cycle, a step-up operation for obtaining the second output voltage Vo2 is performed.

  First, in the first switching cycle, the switch SW2 is turned off, and the boosting operation is performed by turning on and off the switches SW0 and SW1. First, the switch SW0 is turned on, the switch SW1 is turned off, and the charging current is charged in the inductor L (1up: an upward slope portion of the Vo1 period in FIG. 4B). Next, the switch SW0 is turned off, the switch SW1 is turned on, the charging current charged in the inductor L is discharged to the capacitor C1, and the capacitor C1 is charged (1down: falling of the Vo1 period in FIG. 4B) Slope). Then, the first output voltage Vo1 is obtained. At this time, the ratio of the time of the ascending slope with respect to one period is called a time ratio (duty), and the duty is determined by the ratio of the input voltage Vin and the output voltage Vo1.

  Next, in the second switching cycle, the switch SW1 is turned off, and the boosting operation is performed by turning on and off the switches SW0 and SW2. First, the switch SW0 is turned on, the switch SW2 is turned off, and the charging current is charged in the inductor L (2up: the upward slope portion of the Vo2 period in FIG. 4B). Next, the switch SW0 is turned off, the switch SW2 is turned on, the charging current is discharged to the capacitor C2 in the inductor L, and the capacitor C1 is charged (2down: the downward slope portion of the Vo2 period in FIG. 4B). Then, the second output voltage Vo2 is obtained. Two output voltages can be obtained by using the inductors in such a manner as being time-divisionally used alternately. The duty in this case is determined by the ratio between the input voltage Vin and the output voltage Vo2.

  FIG. 5 is a diagram for explaining the influence of cross regulation in a PWM control type multi-output DC / DC conversion circuit. In a multi-output power supply, when the load current fluctuates at the output of one power supply, the phenomenon in which fluctuation (ripple) appears in the output voltage of the other power supply is called cross regulation. FIG. 5 shows the state of cross regulation when the load on the first output voltage Vo1 side is a heavy load and the second output voltage Vo2 is in a steady state.

That is, when a plurality of outputs are taken out, it is an influence that one output has on other outputs. In the case of the 2-output DC / DC converter shown in FIG. 4A, when a load change occurs in one output, the pulse width of the PWM signal applied to the switch changes. For example, when the load on the first output voltage side becomes a heavy load, the pulse width of the PWM signal applied to the switches SW0 and SW1 increases in the first period. That is, the charging current I _L to be charged in the inductor increases. Then, before the charging current I _L is completely discharged to the capacitor C1, the second period is entered, so in the second period, the charging current I _L that was not discharged is partially charged into the capacitor C2, There is a problem that fluctuation occurs in the output Vo2 of No.2.

  In the case of PWM control, when a load fluctuation occurs in the first output and the second output is in a steady state, only one power source can be controlled in one period. Therefore, a long time is required until the output voltage of the channel is stabilized. Necessary and the output power supply ripple becomes large. In other words, since the first period and the second period only alternate, the output voltage ripple must be waited until the next first period in order to reduce the output error voltage by adjusting the pulse width. Becomes larger, which in turn increases the influence of cross regulation. On the other hand, if the control period or control cycle of the power supply of each channel can be controlled in accordance with the output error voltage of each channel, the charging current charged in the inductor L during the control period of one power supply becomes the control period of the other power supply. It can be seen that the output voltage ripple can be reduced in a short time because the capacitor is completely discharged before the transition, and thus the influence of cross regulation can be reduced.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 6 is a circuit configuration diagram for explaining a switching power supply circuit including a single inductor 2-output DC / DC conversion circuit according to the present invention.

  The switching power supply circuit according to the present invention includes a single inductor two-output DC / DC converter circuit (dual boost converter) 130, and a first error amplifier (error) that receives the first output voltage Vo1 and the first reference voltage Vref1. Amplifier) 131, a first comparator (comparator) 133 connected to the first error amplifier 131 and the sawtooth transmission circuit 136, a second output voltage Vo2 and a second reference voltage Vref2 to be input. Two error amplifiers 132 (error amplifiers), a second comparator (comparator) 134 connected to the second error amplifier 132 and the sawtooth wave generation circuit 136, and the first comparator 133 and the second A differential amplifier 135 connected to the comparator 134; a control ratio generator 137 for inputting an output of the differential amplifier 135; A first frequency synthesizer 139 that inputs the output of the comparator 133 and the output of the control ratio generator 137, a second frequency synthesizer 140 that inputs the output of the second comparator 134 and the output of the control ratio generator 137, and a control A ratio generator 137, a switch control circuit 138 for inputting the output of the first frequency synthesizer 139 and the output of the second frequency synthesizer 140. The single inductor 2 output DC / DC conversion circuit 130 is the same as the single inductor 2 output DC / DC conversion circuit 121 shown in FIG.

  In other words, the switching power supply circuit according to the present invention includes a single inductor two-output DC / DC conversion circuit, and compares the output of the error amplifier of the two power supplies or the load current of the two power supplies for each PWM clock cycle. Each control ratio or each control period of the two power sources is determined, and the switching element is switched and controlled. This switching power supply circuit has two channels, and a first output power supply Vo1 is obtained from the first channel, and constitutes a first power supply. Further, the second output power supply Vo2 is obtained from the second channel, and constitutes the second power supply. Further, the switching power supply circuit according to the present invention includes a differential amplifier 135, a control ratio generator 137, a first frequency synthesizer 139, and a second frequency synthesizer 140, and each of the single inductor multiple output DC / DC conversion circuits. A control circuit that selects the channel with the largest error between the value of the output signal in the channel and the desired value, relatively increases the control period of the output signal in the selected channel, and controls the output signal. The channel having the largest error between the value of the output signal and the desired value in each channel of the one-inductor multi-output DC / DC conversion circuit is selected, and only the control cycle of the output signal in the selected channel is shortened. A control circuit that controls the switching is configured.

  When the input voltage is input to the single inductor 2 output DC / DC conversion circuit 130, the output voltage is changed to the first and second error amplifiers 131 and 132, the first and second comparators 133 and 134, and the first voltage. The frequency synthesizer 139, the second frequency synthesizer 140, and the switch control circuit 138 are used to obtain an output voltage from the single inductor 2 output DC / DC conversion circuit 130.

  The operation of the switching power supply circuit of the present invention shown in FIG. 6 will be described below.

  In order to obtain two output voltages Vo1 and Vo2, the switching power supply circuit of the present invention performs charging by providing a period for charging the capacitors C1 and C2 and using the inductor in a time-sharing manner. That is, in the first period out of the two periods, the boosting operation for obtaining the first output voltage Vo1 is performed as the first power supply, and in the second period out of the two periods, the second power supply is used as the second power supply. Step-up operation for obtaining an output voltage Vo2 of 2 is performed.

  First, in the first switching cycle, the switch SW2 is turned off, and the boosting operation is performed by turning on and off the switches SW0 and SW1. First, the switch SW0 is turned on, the switch SW1 is turned off, and the charging current is charged in the inductor L. Next, the switch SW0 is turned off, the switch SW1 is turned on, the charging current charged in the inductor L is discharged to the capacitor C1, and the capacitor C1 is charged. Then, by repeating the charging / discharging operation of the inductor L in the first period, the first output voltage Vo1 is obtained. That is, during the first period, one pulse is input to each of the switches SW0 and SW1, and the boosting operation is performed.

  The first output voltage Vo1 is compared with the reference power supply voltage Vref1 by the first error amplifier 131, and the first output error voltage ΔVo1 is output. The reference power supply voltage Vref1 is a voltage corresponding to a desired first output voltage. The sawtooth wave generation circuit 136 outputs a sawtooth wave voltage Vt whose voltage increases at a predetermined cycle. The first comparator 133 compares the first output error voltage ΔVo1 with the sawtooth voltage Vt and outputs a PWM signal PWM1. Here, when the load R1 becomes a heavy load, the first output error voltage ΔVo1 has a positive voltage value and a large absolute value. That is, the first output error voltage ΔVo1 has a large voltage value. On the other hand, when the load R1 becomes a light load, the first output error voltage ΔVo1 has a negative voltage value and a large absolute value. That is, the first output error voltage ΔVo1 has a small voltage value.

  Next, in the second switching cycle, the switch SW1 is turned off, and the boosting operation is performed by turning on and off the switches SW0 and SW2. First, the switch SW0 is turned on, the switch SW2 is turned off, and the inductor L is charged with a charging current. Next, the switch SW0 is turned off, the switch SW2 is turned on, the charging current charged in the inductor L is discharged to the capacitor C2, and the capacitor C2 is charged. Then, the charging current charged in the inductor L is discharged to the capacitor C2, and the second output Vo2 is obtained. That is, during the second switching cycle, one pulse is input to each of the switches SW0 and SW2, and the boosting operation is performed.

  The second output voltage Vo2 is compared with the reference power supply voltage Vref2 by the second error amplifier 132, and the second output error voltage ΔVo2 is output. The reference power supply voltage Vref2 is a voltage corresponding to a desired second output voltage. The sawtooth wave generation circuit 136 outputs a sawtooth wave voltage Vt whose voltage increases at a predetermined cycle. The second comparator 134 compares the second output error voltage ΔVo2 with the sawtooth voltage Vt and outputs a PWM signal PWM2. Here, when the load R2 becomes a heavy load, the second output error voltage ΔVo2 has a positive voltage value and a large absolute value. That is, the second output error voltage ΔVo2 has a large voltage value. On the other hand, when the load R2 becomes a light load, the second output error voltage ΔVo2 has a negative voltage value and a large absolute value. That is, the second output error voltage ΔVo2 has a small voltage value.

  In the channel switching, first, the first output voltage Vo1 is charged to the capacitor C1 in the first switching cycle, and then the second output voltage Vo2 is charged to the capacitor C2 in the second switching cycle. With this as one channel switching cycle, this channel switching cycle is repeated.

  Here, the output voltage to be controlled is determined by comparing the first output error voltage ΔVo1 and the second output error voltage ΔVo2. This comparison is performed by the differential amplifier 135.

  In the first method, at the start of the first switching cycle in one channel switching cycle, the period of the switching cycle of each power source is not changed, and the cycle for controlling any one power source is shortened. is there. For example, if ΔVo1 is larger than ΔVo2 at the start of the current clock, the cycle corresponding to the control of the output voltage Vo2 is shortened. However, the period of the second switching cycle itself is not changed or shortened. When the period of the second power supply control is shortened, the first control period is relatively long, and the first power supply is controlled with priority, and the first output power supply error ΔVo1 is reduced. . Since the time until the output voltage stabilizes can be shortened, the output power supply ripple when the load fluctuates can be reduced. Further, the charging current charged in the inductor L is sufficiently discharged to the capacitor C before the end of the control period of the power supply, and the influence of cross regulation can be reduced.

  First, the differential amplifier 135 compares the first output error voltage ΔVo1 with the second output error voltage ΔVo2, and outputs a low level (logic value 0) signal when the output error voltage ΔVo1 is large. When the error voltage ΔVo2 is large, a high level (logic value 1) signal is transmitted to the control ratio generator 137 at the start of the switching cycle. The control ratio generator 137 determines a power source and a control cycle for shortening the control cycle from the signal transmitted from the differential amplifier 135. The control cycle to be shortened is determined, for example, by comparing reference power sources built in the control ratio generator 137. The control ratio generator 137 further signals the control cycle to be shortened and transmits the signal to the frequency synthesizer corresponding to the power source on the side to shorten the PWM period.

  For example, when the selector control ratio generator 137 receives a low level signal, the control ratio generator 137 transmits the determined control period to the first frequency synthesizer 139. The first frequency synthesizer 139 shortens the period (control period) of PWM1 transmitted from the first comparator 133 to a period determined by the control ratio generator 137 to be a signal M01, and the signal M01 is changed to the switch control circuit 138. Send to. On the other hand, the second frequency synthesizer 140 uses the PWM signal transmitted from the second comparator 134 as the signal M02 as it is, and transmits the signal M02 to the switch control circuit 138. In this case, in the first switching cycle, the switch control circuit 138 performs ON / OFF control of the switches SW0 and SW1 based on the signal M01, and supplies electric charge to the output capacitor C1 to control the first power supply. Thus, the output voltage Vo1 is corrected. Thereafter, in the second switching cycle, the switches SW0 and SW2 of the inductor L are turned on / off based on the signal M02 to supply charges to the output capacitor C2 and control the second power supply.

  When the control ratio generator 137 receives a high level signal, the control ratio generator 137 transmits the determined control period to the second frequency synthesizer 140. The second frequency synthesizer 140 shortens the period (control period) of PWM2 transmitted from the second comparator 134 to a period determined by the control ratio generator 137 to be a signal M02, and the signal M02 is changed to a switch control circuit 138. Send to. On the other hand, the first frequency synthesizer 139 uses the PWM signal transmitted from the first comparator 133 as the signal M01 as it is, and transmits the signal M01 to the switch control circuit 138. In this case, in the first switching cycle, the switch control circuit 138 performs ON / OFF control of the switches SW0 and SW1 based on the signal M01, supplies electric charge to the output capacitor C1, and controls the first power supply. After that, in the second switching cycle, the switches SW0 and SW2 of the inductor L are turned on / off based on the signal M02, the electric charge is supplied to the output capacitor C2, and the second power source is controlled to correct the output voltage Vo2. To do.

  When the first output error voltage ΔVo1 is smaller than the second output error voltage ΔVo2, the control cycle of the first power supply is shortened, but the control cycle of the second power supply is not shortened. On the other hand, when the second output voltage error ΔVo2 is smaller than the first output voltage error ΔVo1, the control cycle of the first power supply is not shortened, but the control cycle of the second power supply is shortened.

  FIG. 7 shows an inductor when the method of shortening the control cycle of any power source at the start of the switching cycle in the switching power supply circuit having the single inductor two-output DC / DC conversion circuit according to the present invention of FIG. It shows the waveform of current.

  FIG. 7A shows a waveform example of the inductor current when the second output error voltage ΔVo2 is smaller than the first output error voltage ΔVo1. In this case, the control cycle of the first power source is not shortened, but the control cycle of the second power source is shortened.

  FIG. 7B shows an example of the waveform of the inductor current when the first output error voltage ΔVo1 is smaller than the second output error voltage ΔVo2. In this case, the control cycle of the second power source is not shortened, but the control cycle of the first power source is shortened.

  Returning to FIG. 6, the second method is a method of performing control by varying the control duty of the two power supplies at the start of the first switching cycle in one channel switching cycle. For example, when ΔVo1 is larger than ΔVo2 at the start of the switching cycle, the ratio of the first switching cycle corresponding to the control of the output voltage Vo1 is increased without changing the period of one channel switching cycle, and the output voltage Vo2 The proportion of the period of the second switching cycle corresponding to the control is reduced accordingly. By extending the control period of the larger power supply between the output error voltages ΔVo1 and ΔVo2, the output error voltage can be reduced quickly, that is, the time until the output voltage stabilizes can be shortened, so that the load fluctuation time Output voltage ripple can be reduced. Further, the current charged in the inductor L is sufficiently discharged to the capacitor C1 by the end of the control period of the power supply, and the influence of cross regulation can be reduced.

  First, the differential amplifier 135 compares the first output error voltage ΔVo1 with the second output error voltage ΔVo2, and outputs a low level (logic value 0) signal when the output error voltage ΔVo1 is large. When the error voltage ΔVo2 is large, a high level (logic value 1) signal is transmitted to the control ratio generator 137. The control ratio generator 137 determines the time displacement α. Here, α is set to −1 ≦ α ≦ 1, a positive number when a low level signal is received, and a negative number when a high level signal is received. The size is determined by comparison with a reference voltage source built in the control ratio generator 137 or the like. The control ratio generator 137 converts the determined time displacement α into a signal and transmits it to the first frequency synthesizer 139 and the second synthesizer 140. The first frequency synthesizer 139 determines the period of the switching cycle based on the PWM 1 transmitted from the first comparator 133 and the time displacement α transmitted from the control ratio generator 137. In the present invention, assuming that the normal switching cycle period (PWM period) of each power supply is To, the first switching cycle period (control period of the first power supply) is changed to the control signal M01 with (1 + α) To. To the switch control circuit. Further, the second frequency synthesizer 140 determines the control period based on the PWM 2 transmitted from the second comparator 134 and the time displacement α transmitted from the control ratio generator 137. In the present embodiment, the second switching cycle period (second power supply control cycle) is changed to a control signal M02 having (1-α) To and transmitted to the switch control circuit 138.

  The control ratio generator 137 further transmits a selection signal SEL, which is a signal for selecting the first power supply or the second power supply, to the switch control circuit while changing the period. The selection signal SEL normally repeats a low level (logic value 0) and a high level (logic value 1) alternately, and each period is the same as the period of one switching cycle. In the present embodiment, the control ratio generator 137 changes the low level period To of the selection signal SEL to (1 + α) To, changes the high level period To to (1-α) To, and the switch control circuit 138. Send to. However, the total period of the low level period and the high level period does not change.

  In the first switching cycle, the switch control circuit 138 performs ON / OFF control of the switches SW0 and SW1 based on the signal M01, supplies electric charge to the output capacitor C1, and corrects and controls the output voltage Vo1. Thereafter, in the second switching cycle, the switch control circuit 138 drives the switches SW0 and SW2 of the inductor L on / off based on the signal M02, supplies charges to the output capacitor C2, and controls and drives the output voltage Vo2. To do. Thereafter, this operation is repeated.

  When the first output voltage error ΔVo1 is larger than the second output voltage error ΔVo2, the first switching cycle is lengthened and the second switching cycle is shortened. On the other hand, when the second output power supply error ΔVo2 is larger than the first output power supply error ΔVo1, the first switching cycle is shortened and the second switching cycle is lengthened.

  FIG. 8 shows a case where the switching power supply circuit having the single inductor 2 output DC / DC conversion circuit according to the present invention shown in FIG. 6 is controlled by changing the control duty of the two power supplies at the start of the clock. It shows the waveform of the inductor current.

  FIG. 8A shows an example of the waveform of the inductor current when the first output voltage error ΔVo1 is larger than the second output voltage error. In this case, 0 ≦ α ≦ 1, the first switching cycle is longer than the normal first switching cycle ((1 + α) times), and the second switching cycle is longer than the normal second switching cycle. Becomes shorter ((1-α) times).

  FIG. 8B shows a waveform example of the inductor current when the second output error voltage ΔVo2 is larger than the first output error voltage ΔVo1. In this case, −1 ≦ α ≦ 0, the first switching cycle is shorter than the normal first switching cycle period ((1 + α) times), and the second switching cycle is the normal second switching cycle period. Longer ((1-α) times).

  When a load change occurs in one of the outputs, the charge of the output capacitor is temporarily charged and discharged, the output voltage changes, and the output voltage error increases. In such a case, the power supply with the larger output voltage error is preferentially controlled so that the power supply to be controlled is quickly controlled in a direction to reduce the error, and the power supply with the larger error is selected. Stabilize faster. Therefore, the output voltage ripple can be reduced and the influence of cross regulation can be quickly reduced.

  FIGS. 9A to 9C are specific circuit configuration diagrams of the switch control unit in FIG. 6, and FIG. 9A illustrates the output M01 of the first frequency synthesizer 139 and the second frequency synthesizer 140. FIG. 9B is a conceptual diagram for operating each switch in response to the output M02, FIG. 9B is a circuit configuration diagram of the switch control circuit 138, and FIG. 9C is a truth table.

  The switch control circuit 138 receives the output signal M01 of the first frequency synthesizer 139, the output signal M02 of the second frequency synthesizer 140, and the selection signal SEL, and outputs a PWM signal to the switches SW0 to SW2. The selection signal SEL is a signal that determines the first period and the second period. The first period is when the level is low (logical value is 0), and the second period is when the level is high (logical value is 1).

  When the selection signal SEL is 0, the output signal M01 of the first frequency synthesizer 139 is enabled and the output signal M02 of the second frequency synthesizer 140 is disabled. An output signal M01 of the first frequency synthesizer 139 is output to the switch SW0, a signal obtained by inverting the output signal M01 of the first frequency synthesizer 139 is output to the switch SW1, and 0 is output to the switch SW2. Is output.

  When the selection signal SEL is 1, the output signal M01 of the first frequency synthesizer 139 is disabled and the output signal M02 of the second frequency synthesizer 140 is enabled. Then, the output signal M02 of the second frequency synthesizer 140 is output to the switch SW0, 0 is output to the switch SW1, and the switch SW2 is a signal obtained by inverting the output signal M02 of the second frequency synthesizer 140. Is output.

  In this way, the output M01 from the first frequency synthesizer 139 and the output M02 from the second frequency synthesizer 140 are time-divided and supplied to the switches SW0 to SW2 without simultaneously turning on SW1 and SW2. Can do. Thus, the control of Vo1 and Vo2 is selected by the selection signal SEL.

  In the above-described two embodiments, the power source to be controlled and the switching period thereof are determined by comparing the two output voltage errors ΔVo1 and ΔVo2. However, in the other embodiments, the first and second output voltage errors ΔVo instead of the output error voltage ΔVo are determined. The load currents Io1 and Io2 of the second power supply can be compared to determine the power supply to be controlled and its switching period.

  Although the case where the single inductor 2 output DC / DC conversion circuit is used has been described above, it is also possible to use a single inductor multiple output DC / DC conversion circuit. That is, when a single inductor n (n is 2 or more) output DC / DC conversion circuit is used as the single inductor multiple output conversion circuit, the difference between the output voltage of the single inductor n output circuit and the reference voltage N error amplifiers that output the amplified error voltage to n comparators, and n comparisons that output a PWM signal that compares the error voltage output from the error amplifier and the sawtooth wave to the control ratio generator. A container is required.

  Next, a second embodiment of the present invention will be described.

  FIG. 10 is a diagram for explaining a switching power supply circuit including a single inductor 2-output DC / DC conversion circuit according to the present invention, and is a circuit configuration diagram from an error amplifier of each channel to a switch control circuit.

  The switching power supply circuit according to the present invention includes a single inductor two-output DC / DC converter circuit (dual boost converter) 130, and a first error amplifier (error) that receives the first output voltage Vo1 and the first reference voltage Vref1. Amplifier) 131, a second error amplifier 132 to which the second output voltage Vo2 and the second reference voltage Vref2 are input, and an output of the first error amplifier 131 and an output of the second error amplifier 132 are input. A differential amplifier 135, a first sawtooth wave generation circuit 141, a control ratio signal generator 142 that receives the output of the first sawtooth wave generation circuit 141 and the output of the differential amplifier 135, and The second and third sawtooth wave generation circuits 143 and 144 that receive the output of the control ratio signal generator 142, the output ΔVo1 of the first error amplifier 131, and the first The first comparator 145 that receives the output of the sawtooth wave generation circuit 143 as the input, and the second comparator 146 that receives the output Vo2 of the second error amplifier 132 and the output of the second sawtooth wave generation circuit 144 as inputs. It is composed of The control ratio signal generator 142 is composed of a comparator, and outputs a selection signal SEL for selecting a control target from the first power supply and the second power supply to the switch control circuit 138.

  In the second embodiment, the switch control circuit 138 is the same as the first embodiment, and the single inductor two-output DC / DC conversion circuit 130 is the single inductor two-output DC / DC shown in FIG. This is the same as the DC conversion circuit 121.

  That is, the switching power supply circuit according to the present invention includes a single inductor two-output DC / DC conversion circuit, and the first sawtooth shape is obtained by comparing the outputs of the error amplifiers of the two power supplies or comparing the load currents of the two power supplies. Each control ratio or each control period of the two power sources is determined for each cycle of the wave generation circuit 141, and the switching element is controlled to be switched. This switching power supply circuit has two channels, and a first output power supply Vo1 is obtained from the first channel, and constitutes a first power supply. Further, the second output power supply Vo2 is obtained from the second channel, and constitutes the second power supply.

  When the input voltage is input to the single inductor 2 output DC / DC conversion circuit 130, the output voltage is controlled by the first and second error amplifiers 131 and 132, the first and second comparators 133 and 134, and the switch control. The output voltage from the single inductor 2 output DC / DC conversion circuit 130 is obtained through control with the circuit 138.

  The operation of the switching power supply circuit of the present invention shown in FIG. 10 will be described below.

  In order to obtain two output voltages Vo1 and Vo2, the switching power supply circuit of the present invention performs charging by providing a period for charging the capacitors C1 and C2 and using the inductor in a time-sharing manner. That is, in the first period out of the two periods, the boosting operation for obtaining the first output voltage Vo1 is performed as the first power supply, and in the second period out of the two periods, the second power supply is used as the second power supply. Step-up operation for obtaining an output voltage Vo2 of 2 is performed.

  First, in the first period (switching cycle), the switch SW2 is turned off, and the boosting operation is performed by turning on and off the switches SW0 and SW1. First, the switch SW0 is turned on, the switch SW1 is turned off, and the charging current is charged in the inductor L. Next, the switch SW0 is turned off, the switch SW1 is turned on, the charging current charged in the inductor L is discharged to the capacitor C1, and the capacitor C1 is charged. The first output voltage Vo1 is obtained by repeating one period during which the inductor L is charged and discharged. That is, during the first alternating period, one pulse is input to each of the switches SW0 and SW1, and the boosting operation is performed. The first output voltage Vo1 is compared with the reference power supply voltage Vref1 by the first error amplifier 131, and the first output error voltage ΔVo1 is output.

  Next, in the second period (switching cycle), the switch SW1 is turned off, and the boosting operation is performed by turning on and off the switches SW0 and SW2. First, the switch SW0 is turned on, the switch SW2 is turned off, and the inductor L is charged with a charging current. Next, the switch SW0 is turned off, the switch SW2 is turned on, the charging current charged in the inductor L is discharged to the capacitor C2, and the capacitor C2 is charged. The second output Vo2 is obtained by repeating one period in which the charging / discharging operation of the inductor L is repeated. That is, during the second switching cycle, one pulse is input to each of the switches SW0 and SW2, and the boosting operation is performed. The second output voltage Vo2 is compared with the reference power supply voltage Vref2 by the second error amplifier 132, and the second output error voltage ΔVo2 is output.

  The difference between the output ΔVo1 of the first error amplifier 131 and the output ΔVo2 of the second error amplifier 132 is amplified by the differential amplifier 135. The control ratio signal generation circuit 142 receives the output of the differential amplifier 135 and the output of the first sawtooth wave generation circuit 141 as an input, and outputs a control ratio pulse SEL for selecting a power supply to be controlled. This SEL signal is input to the second and third sawtooth wave generation circuits 143 and 144 in the next stage, and generates sawtooth waves having a width corresponding to the L period and H period of the SEL signal, respectively. The second sawtooth wave generation circuit 143 generates a sawtooth wave when the SEL signal is in the L period, and stops when it is in the H period. The third sawtooth wave generation circuit 144 stops when the SEL signal is in the L period, and generates a sawtooth wave when the SEL signal is in the H period.

  The first comparator 145 compares the first output error voltage ΔVo1 with the output of the second sawtooth wave generation circuit 143, and outputs the PWM signal PWM1. The second comparator 146 compares the second output error voltage ΔVo2 with the output of the third sawtooth wave generation circuit 144 and outputs the PWM signal PWM2.

  Channel switching is performed by the SEL signal. First, in the first switching cycle, the first output voltage Vo1 is charged to the capacitor C1, and then in the second switching cycle, the second output voltage Vo2 is charged to the capacitor. Charge C2. With this as one channel switching cycle, this channel switching cycle is repeated. The period of this channel switching cycle is the same as the period of the first sawtooth wave generation circuit 141.

  FIG. 11 is a diagram showing waveforms at each node in the circuit shown in FIG.

  As described above, the control ratio signal generation circuit 142 outputs a PWM signal having a duty corresponding to the difference between the output error voltages ΔVo1 and ΔVo2 as a SEL signal.

  Then, the output of the second sawtooth wave generation circuit 143 that outputs a sawtooth wave during the L period of the SEL signal and stops during the H period is compared with the output error voltage ΔVo1, and the first power supply is turned on. The PWM signal PWM1 to be controlled is output from the first comparator 145 as M01.

In addition, the output of the third sawtooth wave generation circuit 144 that stops during the L period of the SEL signal and outputs a sawtooth wave during the H period is compared with the output error voltage ΔVo2, and the second power supply is turned on. The PWM signal PWM2 to be controlled is output from the second comparator 146 as M02.
In this manner, the power supply of each channel can be controlled for a period corresponding to the ratio of the output voltage error of the power supply in each channel. As a result, the channel with the larger output error voltage can be preferentially controlled, that is, the channel with the larger load current can be preferentially controlled. That is, since the channel with the larger load current can be controlled relatively more than the other channels, the time until the output voltage is stabilized can be shortened.

  Therefore, the output voltage ripple at the time of load change can be reduced, and the influence of cross regulation can be reduced.

1 input DC power supply 21 first main switch 22 second main switch 31 inductor 51 first rectifying means 52 second rectifying means 61 first smoothing means 62 second smoothing means 71 first load 72 second Load circuit 81 control circuit 90 detection circuit 91 PWM circuit 92 logic circuit 101 DC / DC conversion circuit 102 error amplifier 103 comparator 104 sawtooth wave generation circuit 105 PWM circuit 106 switch control circuit 111 conventional 2-output DC / DC conversion circuit 112, 121, 130 Single inductor multiple output DC / DC conversion circuit 131 First error amplifier 132 Second error amplifier 133 First comparator 134 Second comparator 135 Differential amplifier 136 Sawtooth wave generation circuit 137 Control ratio generator 138 Switch control circuit 139 First frequency synthesizer 140 Second frequency synthesizer 141 First sawtooth wave generation circuit 142 Control ratio signal generator 143 Second sawtooth wave generation circuit 144 Third sawtooth wave generation circuit 145 First comparator 146 Second comparator 801 802, 803, 804 Resistor 805, 806 Error amplifier 807 Reference voltage source 808 Oscillator circuit 809, 810 Comparator 811, 812 AND circuit 813 T flip-flop 814 OR circuit 815 NOR circuit

Claims (4)

In a switching power supply circuit for controlling each output voltage of a single inductor multiple output DC / DC converter circuit,
A single inductor multi-output DC / DC converter circuit that converts an input voltage into a plurality of output voltages, the single inductor multi-output DC / DC converter circuit having a plurality of channels, and each of the plurality of channels. From the channel, a single inductor multi-output DC / DC conversion circuit that obtains one output voltage by time-sharing the inductor and performing switching;
For each switching cycle of the switching to obtain the one output voltage, a channel having the largest error between the output voltage and the desired voltage in each channel of the single inductor multiple output DC / DC converter circuit is selected, The total time of the control period of the channel is not changed, and the control period of the output voltage in the selected channel is largely changed relative to the control period of the output voltage in the non-selected channel, and the output voltage in the non-selected channel is changed. The control cycle is changed relatively small with respect to the control cycle of the output voltage in the selected channel, the output voltage is obtained by performing the switching for each channel, and the single inductor multi-output power supply circuit A switching circuit comprising: a control circuit that controls each output voltage. The single inductor multiple output DC / DC conversion circuit is:
An error amplifier that outputs an error between the output voltage and the desired voltage in each channel;
The control circuit includes:
Compare the output of the error amplifier in each channel, select a channel with a large error amplifier output among the channels, and change the total time of the control cycle of each channel without changing the total time of the control cycle of each channel. The output voltage control cycle is changed relatively large with respect to the output voltage control cycle in the non-selected channel, and the output voltage control cycle in the non-selected channel is relative to the output voltage control cycle in the selected channel. The output voltage is obtained by performing the switching control for each of the channels, and the output voltage of the single inductor multi-output power supply circuit is controlled. Switching power supply circuit. In a switching power supply circuit for controlling each output voltage of a single inductor multiple output DC / DC converter circuit,
A single inductor multi-output DC / DC converter circuit that converts an input voltage into a plurality of output voltages, the single inductor multi-output DC / DC converter circuit having a plurality of channels, and each of the plurality of channels. From the channel, a single inductor multi-output DC / DC converter circuit that obtains one output voltage by time-sharing and switching each inductor;
A channel other than the channel having the largest error between the output voltage and the desired voltage in each channel of the single inductor multiple output DC / DC converter circuit is selected for each switching cycle of the switching to obtain the one output voltage. Then, without changing the switching cycle of each channel, the control period of the output voltage in the selected channel is made relatively small with respect to the switching cycle, and the output voltage is obtained by performing the switching for each channel. And a control circuit for controlling each output voltage of the single inductor multi-output power supply circuit. The single inductor multiple output DC / DC conversion circuit is:
An error amplifier that outputs an error between the output voltage and the desired voltage in each channel;
The control circuit includes:
Compare the output of the error amplifier in each channel, select a channel other than the channel with the largest output of the error amplifier among each channel, without changing the total time of the control period of each channel, The control cycle of the output voltage in the selected channel is made relatively small with respect to the channel that is not selected, the output voltage is obtained by performing the switching control for each channel, and the single inductor multi-output power supply circuit 4. The switching power supply circuit according to claim 3, wherein each output voltage is controlled.

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