KR100747212B1 - Switch Capacitor Type Converter and method for controlling thereof - Google Patents

Abstract

The present invention relates to a converter, and more particularly to a switch capacitor type converter and a control method thereof.

The switch capacitor type converter according to the present invention includes an output capacitor, a first switch capacitor unit including a switch and a capacitor, a second switch capacitor unit including a switch and a capacitor, a third switch capacitor unit including a switch and a capacitor, and the second switch capacitor unit. And control means for maintaining the voltage of the output capacitor constant by adjusting the operation of the first, second and third switch capacitor units and the period of charge or discharge of each capacitor.

Converters, Switch Capacitors, Flying Capacitors

Description

Switch Capacitor Type Converter and method for controlling Technical Field

1 shows a simplified illustration of a conventional switch capacitor type converter.

FIG. 2 shows an ON / OFF signal waveform for controlling switches 2, 3, 4 and 5 of the conventional switch capacitor type converter shown in FIG.

3 is a simplified view of another conventional switch capacitor type converter.

4 illustrates an ON / OFF signal waveform for controlling a switch of another conventional switch capacitor type converter shown in FIG. 3.

Figure 5 shows a switch capacitor type converter according to an embodiment of the present invention.

Figure 6 shows a switch signal in which one flying capacitor is charged, with three flying capacitors each discharging two flying capacitors during the T / 3 period.

FIG. 7 illustrates a switch capacitor type converter in which N switch capacitor parts (N is a natural number greater than 3) are connected as another embodiment of the present invention.

FIG. 8 shows the on / off signal of the switch for the switch capacitor type converter shown in FIG.

FIG. 9 is a waveform modified from the waveform shown in FIG. 8.

The present invention relates to a converter, and more particularly to a switch capacitor type converter.

Recently, the development of a converter suitable for a low power power circuit according to the miniaturization trend has been made. These converters are already used in DMB, mobile phones, MP3, digital tuner, LCD module and DVC which are expected to be multifunctional in the future, and due to the expansion of panel size to meet consumer's needs, stable voltage due to load current consumption There is a further need for a converter, an internal power supply circuit capable of supplying a large current.

As such a converter, a switch capacitor type (charge pump structure) converter has been proposed and is still used.

1 shows a simplified illustration of a conventional switch capacitor type converter.

As shown in FIG. 1, the switch capacitor section includes four switches 2, 3, 4, and 5 and a flying capacitor C1. Input power VDD is applied to the input terminal, and output capacitor Cout is connected to the output terminal.

One end of the second switch 2 is connected to the input power supply VDD, and the other end thereof is connected to one end of the flying capacitor C1. One end of the third switch 3 is connected to the ground power supply, and the other end thereof is connected to the other end of the flying capacitor C1. One end of the fourth switch 4 is connected to one end of the flying capacitor C1, and the other end thereof is connected to the output capacitor Cout. One end of the fifth switch 5 is connected to the other end of the flying capacitor C1, and the other end thereof is connected to the input power source VDD.

FIG. 2 shows an ON / OFF signal waveform for controlling switches 2, 3, 4 and 5 of the conventional switch capacitor type converter shown in FIG.

Hereinafter, an operation of a conventional switch capacitor type converter will be described with reference to FIGS. 1 and 2.

In FIG. 2, (a) shows the on / off signal waveforms of the second and third switches 2 and 3, and (b) shows the on / off signal waveforms of the fourth and fifth switches 4 and 5.

As shown in FIG. 2, when the second and third switches 2 and 3 are turned on, the fourth and fifth switches 4 and 5 are turned off. By this switch operation, the input power source VDD charges the flying capacitor C1.

After the flying capacitor C1 is charged for a predetermined time to charge up to the voltage of the input power supply VDD, the fourth and fifth switches 4 and 5 are turned on, and the second and third switches 2, 3) turns off. In this case, the parallel connection between the flying capacitor C1 and the input power source VDD is separated, and the total voltage is boosted to 2VDD by the series connection between the input power source VDD and the flying capacitor C1, and this voltage is connected to the output terminal. Discharged to the output capacitor Cout.

In general, with n external capacitors, the output voltage of the switch capacitor type converter is (n + 1) VDD.

However, the conventional switch capacitor type converter shown in FIG. 1 has a problem in that the output voltage drop due to the load current Iout is large. As shown in FIG. 2, since the fourth and fifth switches 4 and 5 are turned off at the moment when the second and third switches 2 and 3 are turned on, they are output as much as the load current Iout is released. The leakage occurs at the capacitor Cout, which in turn leads to a voltage drop of the output capacitor Cout.

In order to compensate for this disadvantage, there is a structure in which two switch capacitor units are connected in parallel.

3 is a simplified view of another conventional switch capacitor type converter.

The switch capacitor type converter in FIG. 3 is a dual switching type converter.

The switch capacitor type converter shown in FIG. 3 has a structure in which two switch capacitor parts shown in FIG. 1 are connected in parallel. The structure of the switch capacitor part shown in FIG.

4 illustrates an ON / OFF signal waveform for controlling a switch of another conventional switch capacitor type converter shown in FIG. 3.

Hereinafter, the operation of the conventional switch capacitor type converter will be described with reference to FIGS. 3 and 4.

In FIG. 3, (a) shows the on / off signal waveforms of the sixth, seventh, twelfth, and thirteenth switches 6, 7, 12, and 13, and (b) shows the eighth, ninth, tenth, and eighth signals. 11 The on / off signal waveforms of the switches 8, 9, 10, and 11 are shown.

When the sixth and seventh switches 6 and 7 are turned on and the eighth and ninth switches 8 and 9 are turned off, the input power supply VDD is charged to the first flying capacitor C1.

At the same time, when the tenth and eleventh switches 10 and 11 are turned off and the twelfth and thirteenth switches 12 and 13 are turned on, the voltages charged in the input power supply VDD and the second flying capacitor C2 ( VDD) is connected in series so that the total voltage is boosted to 2VDD and discharged to the output capacitor Cout of the output terminal.

During the next period, the switch operates as opposed to the above-described switching operation, thereby charging the output stage output capacitor Cout by this switch operation.

While the first flying capacitor C1 is charged using two first and second flying capacitors C1 and C2, the second flying capacitor C2 discharges, and in the next operation, the first flying capacitor C1 is discharged. Is discharged, the second flying capacitor C2 is charged. As a result, the operation prevents the voltage drop of the output capacitor Cout of the output terminal as much as the load current Iout falls.

The switch capacitor type converter shown in FIGS. 1 and 3 has a structural problem that is vulnerable to a change in the load current Iout. In the dual-switched converter proposed in FIG. 3, the discharge operation is performed to the output capacitor Cout at the output stage during all cycles, but there are some improvements. However, the load current increases according to the structure suitable for the low power and high efficiency circuit and the panel size that increases. There is a problem that can not step up to the desired voltage.

SUMMARY OF THE INVENTION The present invention provides a switch capacitor type converter capable of boosting a desired voltage while maintaining a structure suitable for a low power and high efficiency circuit and increasing a load current according to an increasing panel size, and a control method thereof.

The present invention is to solve the above problems, the switch capacitor converter according to the present invention is an output capacitor; A first switch capacitor unit including a switch and a capacitor; A second switch capacitor unit including a switch and a capacitor; A third switch capacitor unit including a switch and a capacitor; And control means for controlling the period of charge or discharge of each of the capacitors of the first, second and third switch capacitors to maintain a constant voltage of the output capacitor.

Here, the control means preferably controls the operation of the first, second and third switching capacitor.

Here, the switch capacitor unit; A first switch having one side connected to an input terminal and the other side connected to one side of the capacitor; A second switch having one side connected to the ground and the other side connected to the other side of the capacitor; A third switch having one side connected to an output terminal and the other side connected to one side of the capacitor; And a fourth switch having one side connected to the input terminal and the other side connected to the other side of the capacitor. It is preferable to include.

In addition, the first, second and third switch capacitor portion is preferably connected in parallel with the output capacitor.

On the other hand, the switch capacitor type converter further comprises at least one or more switch capacitor unit including the switch and the capacitor, the control means for adjusting the period of charge or discharge of each capacitor of the switch capacitor unit further included the output It is desirable to keep the voltage of the capacitor constant.

The control method of the switch capacitor converter according to the present invention described above comprises the steps of: (a) a capacitor of the first switch capacitor unit is discharged during the first period of the charge capacitor; (b) discharging the capacitor of the second switch capacitor unit during the second period to charge the output capacitor; And (c) discharging the capacitor of the third switch capacitor unit during the third period to charge the output capacitor. It includes.

Here, the first and second periods are preferably the same period.

Here, the switch capacitor type converter further includes at least N switch capacitors (N is a natural number) including a switch and a capacitor, and the control means adjusts the period of charge or discharge of each capacitor of the N switch capacitors. The voltage of the output capacitor is kept constant, and the capacitors of the N switch capacitor parts are discharged for a predetermined period, respectively, and further comprising the step of charging the output capacitor.

In addition, it is preferable that M (M is a natural number) capacitors of the N capacitors of the N switch capacitor units are discharged for the same period to charge the output capacitor.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

Figure 5 shows a switch capacitor type converter according to an embodiment of the present invention.

As shown in FIG. 5, the switch capacitor converter according to the present invention has a structure in which three switch capacitor units including flying capacitors C1, C2, and C3 are connected in parallel. The structure of each switch capacitor portion is similar to that in FIG. 1 and will be omitted. However, a control means 26 for controlling the operation of each switch capacitor unit and each switch is further included. The control means 26 allows the voltage to be increased to the desired voltage while increasing the load current Iout, thereby controlling the charging time and the discharging time to optimize the control of the efficient charging, discharging time and switching operation signals. do.

The control means 26 controls the operation of the switch capacitor portion and the operation of the switch.

The control means 26 controls the operation of the switch capacitor portion means that two switch capacitor portions of the three switch capacitor portions are operated, and the remaining one switch capacitor portion is not operated. This can reduce unnecessary power consumption when supplying sufficient load current by only two switch capacitors.

The control means 26 controls the operation of the switch means adjusting the on / off period of the switch, which will be described with reference to FIG. 6.

Figure 6 shows a switch signal in which one flying capacitor is charged, with three flying capacitors each discharging two flying capacitors during the T / 3 period.

First, the operation during the first T / 3 period in the period in which one cycle is T will be described.

While the sixteenth and seventeenth switches 16 and 17 are turned on and the voltage of the first flying capacitor C1 is discharged, at the same time, the twenty-fourth and twenty-seventh switches 24 and 25 are turned on so that the flying capacitor C3 is turned on. Discharge the voltage at the same time. As the eighteenth and nineteenth switches 18 and 19 are turned on, the second flying capacitor C2 is charged.

As a result, during this period, the first flying capacitor C1 and the third flying capacitor C3 discharge simultaneously, and the second flying capacitor C2 charges.

The 16th and 17th switches 16 and 17 are on as they are, and the 24th and 25th switches 24 and 25 are turned off, and in the second T / 3 period, one period is T. And the 23rd switches 22 and 23 are turned on to start charging the third flying capacitor C3. As the 18th and 19th switches 18 and 19 are turned off in the same period, the 20th and 21st switches 20 and 21 are turned on and the second flying capacitor C2 starts to discharge.

As a result, during this period, the first flying capacitor C1 and the second flying capacitor C2 discharge simultaneously, and the third flying capacitor C3 charges.

 If the above operation is repeated every interval, the output capacitor Cout of the output stage always discharges two of the three flying capacitors to supply power to boost the output voltage of the output stage, and the remaining one of the flying capacitors is T /. Charge for 3 hours.

In this way, a switch capacitor type converter capable of stepping up to a desired voltage while dealing with an increase in the load current Iout is realized.

The present invention does not merely increase the switch capacitor portion from two to three. The present invention is to maintain a constant output voltage despite the change caused by the increase in the load current of the output capacitor, and when the load current increases, one or more flying capacitors to charge the output capacitor to match the output voltage to match Will be kept. In addition, it is possible to minimize the power consumption by adjusting the charging period of the flying capacitor according to the load current.

As a result, the present invention provides a switch capacitor type converter capable of controlling the charging and discharging time and switching operation, which are optimized for the amount of load current and power consumption.

Accordingly, the technical idea of the present invention is not limited to the structure of the switch capacitor converter shown in FIGS. 5 and 6 and the on / off signal of the switch thereof, and the on / off signal of the switch of the switch capacitor converter may not be periodic. In the periodic case, it will be apparent to those skilled in the art that one flying capacitor may be provided between two or more chargers in one cycle.

Hereinafter, an exemplary embodiment of a structure in which four or more switch capacitor units shown in FIG. 1 are connected in parallel will be described.

 FIG. 7 illustrates a switch capacitor type converter in which N switch capacitor parts (N is a natural number greater than 3) are connected as another embodiment of the present invention.

The N switch capacitor parts include flying capacitors C1 to CN for each switch capacitor part. C1 is a first flying capacitor, and CN means an Nth flying capacitor. Since the structure of the switch capacitor shown in FIG. 1 is connected in parallel, description thereof will be omitted. However, a control means 30 for controlling the operation of each switch capacitor unit and each switch is further included. The control means 30 allows the voltage to be increased to a desired voltage while increasing the load current Iout, thereby controlling the charging time and the discharging time, thereby optimizing the efficient charging, discharging time control, and control of the switching operation signal. do.

The control means 30 controls the operation of the switch capacitor unit and the operation of the switch.

The control means 30 controls the operation of the switch capacitor unit by operating the switch capacitor unit of A (N is a natural number) of the N switch capacitor units (N is a natural number greater than 4), and the remaining NA switch capacitor units are It doesn't work. As a result, unnecessary power consumption can be reduced.

The control means 30 controls the operation of the switch means adjusting the on / off period of the switch, which will be described with reference to FIGS. 8 and 9.

FIG. 8 shows the on / off signal of the switch for the switch capacitor type converter shown in FIG.

Similar to the signal waveform in FIG. 6, the number of switches increases as the flying capacitor increases, but the operation of the overall on / off signal is similar.

That is, when using N flying capacitors, N-1 flying capacitors discharge the output capacitor at the same time, and one flying capacitor charges.

Referring to the operation of the first flying capacitor C1 shown in FIG. 8, the battery is discharged for T * {(N-1) / N} time and charged for T * (1 / N) time. This reduces the unnecessary charging time, while increasing the discharge time and the number of flying capacitors to discharge, thereby effectively reducing the voltage drop of the output capacitor Cout of the output terminal due to the increase in the load current Iout.

FIG. 9 is a waveform modified from the waveform shown in FIG. 8.

As shown in FIG. 8, the switch signal waveform of FIG. 9 shows an operation when the charging time is doubled when using N flying capacitors, and the period T is the same condition.

In this case, the number of flying capacitors discharged to the output capacitor Cout at the output stage is N-2.

Referring to the operation of the first flying capacitor C1 of FIG. 9, charging is performed for T * (2 / N) time and discharged for T * {(N-2) / N} time. This shows that the charging and discharging times operate under different conditions as shown in FIG. 8.

 Therefore, the charging and discharging time of the N flying capacitors may be adjusted to control the discharge efficiency delivered to the output terminal.

This controls the switching operation while varying the number of flying capacitors with the voltage drop according to the load current, thereby efficiently improving the output voltage.

If the discharge time is unnecessarily long or there are many flying capacitors that discharge simultaneously, the charging time, T * (1 / N), is increased by an integer multiple (M) to make T * (M / N), while the discharge time Reduce by T * {(NM) / N} Of course, the number of simultaneous discharge flying capacitors is also reduced by N-M.

According to the present invention, the voltage drop of the output terminal voltage according to the load current increases the flying capacitor and controls the switching operation of the flying capacitor, thereby controlling the number of simultaneous discharge flying capacitors, the charging time and the discharge time of the flying capacitor. It will optimize the charge, discharge time control and control of switching operation signals.

Claims (9)

Output capacitors; A first switch capacitor unit including a switch and a capacitor; A second switch capacitor unit including a switch and a capacitor; A third switch capacitor unit including a switch and a capacitor; And And control means for controlling a period of charge or discharge of each of the capacitors of the first, second, and third switch capacitors to maintain a constant voltage of the output capacitor. According to claim 1, And said control means controls the operation of said first, second and third switching capacitor portions. According to claim 1, The switch capacitor portion The capacitor; A first switch having one side connected to an input terminal and the other side connected to one side of the capacitor; A second switch having one side connected to the ground and the other side connected to the other side of the capacitor; A third switch having one side connected to an output terminal and the other side connected to one side of the capacitor; And A fourth switch having one side connected to the input terminal and the other side connected to the other side of the capacitor; Switched capacitor type converter comprising a. According to claim 1, And the first, second and third switch capacitors are connected in parallel with the output capacitor. According to claim 1, The switch capacitor type converter further includes at least one switch capacitor unit including the switch and the capacitor, And the control means adjusts a period of charge or discharge of each capacitor of the switch capacitor unit further included to maintain a constant voltage of the output capacitor. In the switch control method of a switch capacitor type converter according to claim 1, (a) discharging the capacitor of the first switch capacitor unit during the first period to charge the output capacitor; (b) discharging the capacitor of the second switch capacitor unit during the second period to charge the output capacitor; And (c) discharging the capacitor of the third switch capacitor unit during the third period to charge the output capacitor; Control method of a switch capacitor type converter comprising a. The method of claim 6, And the first and second periods are the same period. The method of claim 6, The switch capacitor type converter further includes at least N switch capacitor units (N is a natural number) including a switch and a capacitor. The control means maintains the voltage of the output capacitor constant by adjusting the period of charge or discharge of each capacitor of the N switch capacitor units, And the capacitors of the N switch capacitor units are discharged for a predetermined period to charge the output capacitors. The method of claim 8, M (M is a natural number) capacitors of the N capacitors of the N switch capacitor unit is discharged during the same period to charge the output capacitor.

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