JP2010074892A - Power supply circuit, and switching control method of power supply circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the width of an output ripple for eliminating noise, and to achieve high efficiency in a situation that a noise countermeasure is not needed. <P>SOLUTION: This power supply circuit is characterized in that: the power supply circuit includes: a plurality of switching output circuits, a switching means for performing the switching control of each switching output circuit, and a start/stop means for starting or stopping the switching output circuit; the switching means performs control so that switching phases inputted into the switching output circuits differ from one another; and the start/stop means controls only one switching output circuit so as to be brought into a starting state when the switching output circuit is in a low-current state, and controls the other switching output circuits so as to be brought into stopping states. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply circuit including a plurality of switching output circuits and a switching control method for the power supply circuit.

  In general, a dropper regulator or a switching regulator such as a DC-DC converter or a charge pump is used as an IC power supply circuit. Among these, the dropper regulator has a small output noise generation amount as a main feature, and is often used as a wireless power source. However, if the output current is large, there is a disadvantage that power loss increases and heat is generated. On the other hand, the switching regulator can obtain high-efficiency power, but noise due to the switching operation occurs.

  In a portable terminal such as a cellular phone, a method of supplying power using a DC-DC converter is adopted for a CPU or an IC requiring a large current. Therefore, in order to prevent wireless sensitivity suppression, noise countermeasures are taken against noise generated from the DC-DC converter. For example, in mobile terminals, noise reduction and noise diffusion can be achieved by implementing measures using external parts such as mounting bypass capacitors in the output line, installing shields in the power supply circuit, and building filters. I'm trying to prevent it. However, in such a portable terminal, there are problems such as an increase in cost and an increase in mounting area due to the addition of peripheral components as a noise removal measure.

  As a technique related to noise countermeasures in a power supply circuit, for example, in Patent Document 1, in a DC-DC converter of a switch control system, a plurality of switching circuits are turned on / off with the same cycle and different phases. It is described that high-quality exchange output with less ripple can be obtained with high efficiency. Further, for example, Patent Document 2 describes a multi-phase DC / DC converter that supplies one output voltage to one load by turning on / off a plurality of switches with the same period and different phases. Yes.

JP 2002-044941 A JP 2006-340442 A

  If the related techniques described in Patent Document 1 and Patent Document 2 are used, a plurality of switches can be turned on / off with the same period and different phases, which can contribute to noise reduction to some extent. However, only the on / off operation of the switch is performed, and conversely, high efficiency cannot be achieved in a situation where noise countermeasures such as ripple removal are unnecessary.

  Therefore, the present invention provides a power supply circuit that can suppress the output ripple width for noise removal and can achieve high efficiency in a situation where noise countermeasures are unnecessary, and a switching control method for the power supply circuit. Objective.

  A power supply circuit according to the present invention includes a plurality of switching output circuits, switching means for performing switching control of each switching output circuit, and start / stop means for starting or stopping each switching output circuit, and the switching means includes each switching output circuit. The switching phase input to the circuit is controlled to be different, and the start / stop means controls only one switching output circuit to the start state and the other switching output circuit to the stop state when the current is in a low current state. It is characterized by doing.

  A switching control method for a power supply circuit according to the present invention is a switching control method for a power supply circuit having a plurality of switching output circuits, wherein the switching phase input to each switching output circuit is controlled to be different, and a low current state is achieved. In this case, only one switching output circuit is controlled to be in a start state, and the other switching output circuit is controlled to be in a stop state.

  According to the present invention, the output ripple width can be suppressed for noise removal, and high efficiency can be achieved in a situation where noise countermeasures are unnecessary.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a configuration of a power supply circuit including a plurality of DC-DC converter output circuits according to the present invention. As shown in FIG. 1, the power supply circuit includes a power supply input circuit 11, two DC-DC converter output circuits 12 and 13, a feedback circuit 14, a divider circuit 15, and a switching circuit 16. In the example shown in FIG. 1, a case where the power supply circuit includes two DC-DC converter output circuits 13 and 14 will be described first for the sake of easy understanding. Further, the power supply circuit shown in the present embodiment is mounted on a mobile terminal such as a mobile phone, for example.

  The power input circuit 11 has a function of receiving input power from the outside (for example, a battery mounted on a mobile phone). The DC-DC converter output circuits 12 and 13 have a function of DC-DC converting and outputting the input power supplied from the power input circuit 11. The feedback circuit 14 has a function of feeding back (outputting) an appropriate output voltage / current control signal to the DC-DC converter output circuit 12 and the DC-DC converter output circuit 13 based on the divided voltage signal from the divider circuit 15. . The divider circuit 15 has a function of dividing the output feedback voltage and outputting the divided signal to the feedback circuit 14. The switching circuit 16 has a function of performing switching control of the DC-DC converter output circuit 12 and the DC-DC converter output circuit 13.

  Next, the operation will be described. In the example shown in FIG. 1, the power supply circuit is equipped with two DC-DC converter output circuits. Therefore, the switching circuit 16 performs control so that the switching phases input to the DC-DC converter output circuit 12 and the DC-DC converter output circuit 13 are different by 180 degrees. For example, the switching circuit 16 performs switching control so that the DC-DC converter output circuit 12 has a switching phase of 0 degrees and the DC-DC converter output circuit 13 performs switching so that the switching phase becomes 180 degrees in the same cycle. Control.

  Further, the output voltages of the two DC-DC converter output circuits 12 and 13 are set to be the same voltage, and the voltage dividing ratio of the voltage dividing signal output from the divider circuit 15 is set to ½.

  By controlling as described above, when the output voltages / currents output from the two DC-DC converter output circuits 12 and 13 are combined, they are combined in opposite phases, and the AC (alternating current) component is canceled by canceling the phase difference. Suppress. As a result, the output ripple width due to the switching operation can be suppressed.

  FIG. 2 is an explanatory diagram showing a specific example of the waveform of the output voltage output from the power supply circuit shown in FIG. Among these, FIG. 2A shows a specific example of the waveform of the output voltage Vout1 output from the DC-DC converter output circuit 12. FIG. FIG. 2B shows a specific example of the waveform of the output voltage Vout2 output from the DC-DC converter output circuit 13.

  Also, the output voltages shown in FIGS. 2A and 2B are synthesized at a synthesis point (point 17 shown in FIG. 1) provided on the output side of the DC-DC converter output circuits 12 and 13. FIG. 2C shows a specific example of the waveform of the synthesized output voltage Vout_all synthesized at the synthesis point 17.

  As already described, since the switching phase of the DC-DC converter output circuit 12 and the DC-DC converter output circuit 13 is shifted by 180 degrees and synthesized in the opposite phase, the ripple of the output synthesized waveform is greatly suppressed. It will be.

  For example, in FIG. 2C, the value Aall at a certain time in the combined voltage Vout_all is the value of the upper limit peak point A1 of the output voltage waveform of the DC-DC converter output circuit 12 and the value of the DC-DC converter output circuit 13. This is a value obtained by combining the value of the lower limit peak point A2 of the output voltage waveform. The value Ball at another time of the combined voltage Vout_all is the value of the lower limit peak point B1 of the output voltage waveform of the DC-DC converter output circuit 12 and the upper limit peak of the output voltage waveform of the DC-DC converter output circuit 13. This is a value obtained by combining the value of the point B2. As shown in FIG. 2 (c), the combined voltages Aall and Ball have the same potential, and this can also be said for the value of the combined voltage at other times. The value of the combined voltage Vout_all is the same potential. It becomes a constant waveform.

  That is, only the added DC (direct current) component remains in the output voltage composite wave of the DC-DC converter output circuit 12 and the DC-DC converter output circuit 13, and the AC component due to the switching operation is removed. . For this reason, the output ripple is suppressed in the output voltage composite waveform Vout_all, and as a result, it is possible to obtain highly accurate output power with less noise components.

  Next, a power supply circuit in which the DC-DC converter output circuit has a multistage configuration will be described. FIG. 3 is a block diagram showing an example of the configuration of a power supply circuit in which the DC-DC converter output circuit is further multi-stage configured. As shown in FIG. 3, the power supply circuit includes a power supply input circuit 31, a plurality of DC-DC converter output circuits 32 to 34, a feedback circuit 35, a divider circuit 36, and a switching circuit 37.

  The power input circuit 31 has a function of receiving input power from the outside (for example, a battery mounted on a mobile phone). The DC-DC converter output circuits 32 to 34 have a function of DC-DC converting and outputting the input power supplied from the power input circuit 31. The feedback circuit 35 has a function of feeding back (outputting) an appropriate output voltage / current control signal to the DC-DC converter output circuits 32 to 34 based on the divided voltage signal from the divider circuit 36. The divider circuit 36 has a function of dividing the output feedback voltage and outputting the divided signal to the feedback circuit 35. The switching circuit 37 has a function of performing switching control of the DC-DC converter output circuits 32 to 34.

  Next, the operation of the power supply circuit having a multi-stage DC-DC converter output circuit will be described. When the DC-DC converter output circuit has a multi-stage configuration, the switching phase difference for canceling the phase at the time of output synthesis can be calculated by 360 degrees / N1 (N1 is the number of DC-DC converter output circuits mounted). For example, when the power supply circuit performs output synthesis using four DC-DC converter output circuits, the switching circuit 37 causes a phase difference of 360 degrees / 4 = 90 degrees between the DC-DC converter output circuits. The switching operation may be performed. In this case, since the output voltage is made the same between the DC-DC converter output circuits 32, the voltage dividing ratio of the divided signal output from the divider circuit 36 is set to be 1/4.

  By controlling as described above, when the output voltages / currents output from the DC-DC converter output circuits 32 to 34 are combined, they are combined in opposite phases, and the AC component is suppressed by canceling the phase difference. Therefore, even when the DC-DC converter output circuit is configured in multiple stages, the output ripple width due to the switching operation can be suppressed.

  In the above description, the case where the output voltages of all the DC-DC converter output circuits 32 to 34 mounted on the power supply circuit are combined has been described. However, the power supply circuit can output each DC-DC converter output circuit only when necessary. Control is performed to synthesize output voltages of 32 to 34.

  In the present embodiment, each DC-DC converter output circuit 32 to 34 is equipped with an output voltage variable circuit. For example, each of the DC-DC converter output circuits 32 to 34 includes a DAC circuit as an output voltage variable circuit.

  For example, in a low current state such as in a standby state, the ripple does not matter so much, so the switching circuit 37 causes any one DC-DC converter output circuit to operate independently, and the other DC -Control the DC converter output circuit to the stop state. In this case, the DC-DC converter output circuit itself is controlled to be in a stopped state, so that the DC-DC converter output circuit is in a state where only a leakage current of the order of several μA flows.

  On the other hand, when ripple removal control is required, such as when a high current state is in progress such as during a call or during communication, the switching circuit 37 activates a plurality of (for example, all) DC-DC converter output circuits 32-34. To control the operation state. And the output voltage of each DC-DC converter output circuit 32-34 is adjusted using the DAC circuit mounted in DC-DC converter output circuit 32-34.

  Note that the power supply circuit may include a DC-DC converter start / stop circuit that starts each DC-DC converter output circuit 32 to 34 or controls the DC-DC converter output circuits 32 to 34 to a stop state.

  That is, in this embodiment, only the DC component needs to be considered. Therefore, when the output voltage when the DC-DC converter output circuit is activated alone is Vout1, the output voltage when a plurality of DC-DC converter output circuits are activated is obtained. , Vout1 / N2 (N2 is the number of activations of the DC-DC converter output circuit). Further, feedback can be easily performed by changing the setting of the voltage dividing ratio of the divided voltage signal output from the divider circuit 36 in accordance with the setting of the output voltage.

  In the present embodiment, the case where a DC-DC converter output circuit is used as the switching operation circuit has been described. However, any other switching operation circuit can be used as long as the output circuit performs a switching operation such as a charge pump. Is possible.

  As described above, according to the present embodiment, the power supply circuit includes a plurality of output circuits that perform a switching operation such as a DC-DC converter output circuit. Then, the power supply circuit causes the switching phase to transition between the DC-DC converter output circuits to synthesize outputs. By doing so, the output ripple width, which is AC noise, can be suppressed, and more accurate output can be achieved.

  On the other hand, in the case of a low current state such as in a standby state, the ripple does not matter so much. Therefore, the power supply circuit operates any one DC-DC converter output circuit independently, and the other DC -Control the DC converter output circuit to the stop state. That is, the DC-DC converter output circuit itself is controlled to be stopped. Therefore, the output ripple width can be suppressed for noise removal, and high efficiency can be achieved in a situation where noise countermeasures are unnecessary.

  For example, in Japanese Patent Application Laid-Open No. 2002-044941 and Japanese Patent Application Laid-Open No. 2006-340442, only the on / off operation of the switch is performed, so that high efficiency can be sufficiently achieved in a situation where noise countermeasures are unnecessary. I can't. On the other hand, according to the present embodiment, the DC-DC converter output circuit itself is controlled to be in a stopped state in a low current state such as in a standby state. Therefore, higher efficiency can be achieved in situations where no countermeasure against noise is required.

  Next, the minimum configuration of the power supply circuit according to the present invention will be described. FIG. 4 is a block diagram illustrating a minimum configuration example of the power supply circuit. As shown in FIG. 4, the power supply circuit includes a plurality of DC-DC converter output circuits 32 to 34 and a switching circuit 37 that performs switching control of each of the DC-DC converter output circuits 32 to 34. The switching circuit 37 has a function of starting or stopping each of the DC-DC converter output circuits 32 to 34. The switching circuit 37 controls the switching phases input to the DC-DC converter output circuits 32 to 34 to be different, and controls only one DC-DC converter output circuit to the start-up state in the low current state. Then, the other DC-DC converter output circuit is controlled to be stopped.

  According to the power supply circuit having the minimum configuration shown in FIG. 4, the output ripple width can be suppressed for noise removal, and high efficiency can be achieved in a situation where noise countermeasures are unnecessary.

  In the present embodiment, the characteristic configuration of the power supply circuit as shown in the following (1) to (5) is shown.

(1) The power supply circuit includes a plurality of switching output circuits (for example, DC-DC converter output circuits 32 to 34), switching means (for example, switching circuit 37) for performing switching control of each switching output circuit, and each switching output. Start / stop means (for example, switching circuit 37) for starting or stopping the circuit, the switching means is controlled so that the switching phase input to each switching output circuit is different, and the start / stop means is in a low current state. In this case, only one switching output circuit is controlled to be in a start state, and the other switching output circuit is controlled to be in a stop state.

(2) In the power supply circuit, when the mobile stop means is in a high current state, the plurality of switching output circuits are controlled to be in the start state, and the switching means is configured to bring the plurality of switching output circuits into the start state by the start stop means. When controlled, the switching phase input to each switching output circuit may be controlled to be different.

(3) In the power supply circuit, the switching means is configured to control the phase of the switching phase input to each switching output circuit so that a phase difference of 360 degrees / number of switching output circuits occurs between the switching output circuits. May be.

(4) The power supply circuit appropriately divides the output feedback voltage and outputs a divided signal based on the divided signal output from the divided signal output means (for example, the divider circuit 36) and the divided signal output means. Feedback means (for example, feedback circuit 35) that feeds back an output voltage / current control signal to each switching output circuit may be provided.

(5) The power supply circuit may be configured to include a plurality of DC-DC converter output circuits as a switching output circuit.

  The present invention can be applied to an electronic device such as a portable terminal equipped with a power supply circuit including a plurality of DC-DC converter output circuits.

It is a block diagram which shows an example of a structure of the power supply circuit provided with the several DC-DC converter output circuit by this invention. FIG. 2 is an explanatory diagram illustrating a specific example of a waveform of an output voltage output from the power supply circuit illustrated in FIG. 1. It is a block diagram which shows an example of a structure of the power supply circuit which made the DC-DC converter output circuit multistage structure further. It is a block diagram which shows the minimum structural example of a power supply circuit.

Explanation of symbols

11, 31 Power input circuit 12, 13, 32, 33, 34 DC-DC converter output circuit 14, 35 Feedback circuit 15, 36 Divider circuit 16, 37 Switching circuit 17 Synthesis point

Claims (7)

A plurality of switching output circuits;
Switching means for performing switching control of each switching output circuit;
Starting and stopping means for starting or stopping each switching output circuit,
The switching means controls the switching phase input to each switching output circuit to be different,
The power supply circuit characterized in that the start / stop means controls only one switching output circuit to a start state and controls another switching output circuit to a stop state when in a low current state. In the case of a high current state, the mobile stop means controls a plurality of switching output circuits to a start state
2. The power supply circuit according to claim 1, wherein the switching unit controls the switching phase input to each of the switching output circuits to be different when the plurality of switching output circuits are controlled to be in the activated state by the activation and deactivation unit.   3. The power supply circuit according to claim 1, wherein the switching means controls the phase so that a phase difference of 360 degrees / number of switching output circuits is generated between the switching output circuits with respect to the switching phase input to each switching output circuit. A divided signal output means for dividing the output feedback voltage and outputting a divided signal;
The feedback means which feeds back an appropriate output voltage / current control signal to each switching output circuit on the basis of the divided signal output from the divided voltage signal output means. The power supply circuit according to item 1.   The power supply circuit according to claim 1, comprising a plurality of DC-DC converter output circuits as the switching output circuit. A switching control method for a power supply circuit including a plurality of switching output circuits,
Control so that the switching phase input to each switching output circuit is different,
A switching control method for a power supply circuit, characterized in that, in a low current state, only one switching output circuit is controlled to be in a starting state and the other switching output circuits are controlled to be in a stopped state. When in a high current state, control a plurality of switching output circuits to a start state,
The switching control method for a power supply circuit according to claim 6, wherein when a plurality of switching output circuits are controlled to be in an activated state, control is performed so that a switching phase input to each switching output circuit is different.

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