KR100747315B1 - Circuit for charge pump - Google Patents

Abstract

The present invention relates to a pump circuit, and more particularly to a high efficiency charge pump circuit used in the power supply of the liquid crystal display panel.

The charge pump circuit according to the present invention comprises a pump circuit including a charging capacitor, a charging switch unit, a discharge switch unit and an output capacitor, each of which includes auxiliary means for reducing switching resistance of the charging switch unit and the discharge switch unit. It is characterized by being.

Charge Pumps, LCDs, Switching Resistors, Variable Frequency, Parallel, Liquid Crystal Display Panels, Power Supplies

Description

Charge pump circuit. {CIRCUIT FOR CHARGE PUMP}

1 is a circuit diagram of a conventional DC-DC charge pump.

2A and 2B show switching cycles as the magnitude of the load of the conventional DC-DC charge pump circuit changes.

3 is a charge pump circuit diagram according to the present invention.

** Explanation of symbols on main parts of the drawing **

310: pump circuit unit 310a: charging switch unit

310b: discharge switch 311: first switch

312: second switch unit 313: third switch unit

314: fourth switch unit 320: control unit

321: comparator 322: oscillator

C _flying : charging capacitor C _OUT : output capacitor

I _LOAD : Load Current Source

The present invention relates to a pump circuit, and more particularly to a high efficiency DC-DC charge pump circuit used in the power supply of the liquid crystal display panel.

As the resolution of the liquid crystal display panel increases, the importance of saving power consumption of the small system becomes more important, and the efficiency of the DC-DC charge pump circuit included in the small system becomes important.

1 is a circuit diagram of a conventional DC-DC charge pump.

As shown in FIG. 1, a conventional DC-DC charge pump circuit includes a pump circuit unit 110 and a controller 120.

<Configuration>

The pump circuit unit 110 includes a first switch SW ₁₁ , a second switch SW ₁₂ , a third switch SW ₁₃ , a fourth switch SW ₁₄ , and a charging capacitor C _flying .

The controller 120 is composed of an oscillator 122 and a comparator 121.

In addition, the DC-DC charge pump circuit further includes a first resistor R ₁₁ , a second resistor R ₁₂ , an output capacitor C _OUT , and a load current source I _LOAD .

<Description>

Charging or discharging occurs in the charging capacitor C _flying by switching the first to fourth switches SW ₁₁ , SW ₁₂ , SW ₁₃ , and SW ₁₄ configured in the pumping circuit 110.

That is, the pumping circuit 110 in accordance with an output voltage (V _OUT) and first and second control signal (Signal _control1, Signal _control2) of the oscillator 122 in accordance with the comparison value compared with a reference voltage (V _REF) The switching speeds of the first to fourth switches SW ₁₁ , SW ₁₂ , SW ₁₃ , and SW ₁₄ are determined.

That is, when the load current source I _LOAD increases, the switching speed of the first to fourth switches SW ₁₁ , SW ₁₂ , SW ₁₃ , and SW ₁₄ increases, and when the load current source I _LOAD decreases, The switching speed of the fourth switches SW ₁₁ , SW ₁₂ , SW ₁₃ , and SW ₁₄ is reduced.

Here, the description of switching will be described in detail with reference to FIGS. 2A and 2B.

By this structure, the pumping circuit 110 has a high efficiency according to the load variation.

In other words, when the load is small, the speed is not increased more than necessary, so the power consumption is reduced, thereby increasing the efficiency.

2A and 2B show switching cycles as the magnitude of the load of the conventional DC-DC charge pump circuit changes.

A control signal (Signal _control1, Signal _control2) shown in Figure 2a is in the light load period is longer that the control cycle of the oscillator signal 122 to reduce the amount of current charged into the charging capacitor (C _flying).

Here, the first switch SW ₁₁ and the second switch SW ₁₂ are switched by the control signal in phase, and the third switch SW ₁₃ and the fourth switch SW ₁₄ are switched by the control signal in phase. The first switch SW ₁₁ , the second switch SW ₁₂ , the third switch SW ₁₃ , and the fourth switch SW ₁₄ have a phase difference of 90 °.

When the first to fourth switches SW ₁₁ , SW ₁₂ , SW ₁₃ , and SW ₁₄ are pumped by the cycle and the load current I _LOAD increases, the switching period is adjusted as shown in FIG. 2B to charge the battery. Increase the charge of the capacitor (C _flying ).

However, only the switching speeds of the first to fourth switches SW ₁₁ , SW ₁₂ , SW ₁₃ , and SW ₁₄ have limitations in ensuring high efficiency.

An object of the present invention for solving the above problems is to provide a high efficiency charge pump circuit according to the size of the load.

A charge pump circuit according to the present invention for solving the above problems is a pump circuit including a charging capacitor, a charging switch unit, a discharge switch unit and an output capacitor, the switching of the charging switch unit and the discharge switch unit An auxiliary means for reducing the resistance is characterized in that each is included.

Here, it is preferable that the above-mentioned auxiliary means is a switching means.

Here, it is preferable that the above-mentioned switching means is either a switch or a transistor.

Here, it is preferable that the above-described auxiliary means is connected in parallel to the charging switch unit and the discharge switch unit, respectively.

Here, it is preferable that the above-mentioned auxiliary means for the charging switch unit and the auxiliary means for the discharge switch unit have a structure capable of independently switching.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

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

3 is a charge pump circuit diagram according to the present invention.

As shown in FIG. 3, the charge pump circuit according to the present invention includes a pump circuit unit 310 and a controller 320.

<Configuration>

The pump circuit unit 310 includes a charge switch unit 310a, a discharge switch unit 310b, and a charge capacitor C _flying .

The charging switch unit 310a includes a first switch unit 311 for switching the input voltage to be applied to the charging capacitor C _flying and a third switch unit 313 for switching to be connected to the ground.

Here, the first switch unit 311 includes a first switch SW _31a which is a main switch of the first switch unit 311 and a first switch SW _{31b which} is an auxiliary means for assisting the main switch.

Here, the third switching unit 313 is a third of the switch 3b (SW _32b) of the main switch of the switch unit 313, the switch 3a (SW _32a) and the auxiliary means for assisting the main switch.

The discharge switch unit 310b includes a fourth switch unit 314 for switching the charging voltage of the charging capacitor C _flying to discharge and a second switch unit 312 for switching in connection with the ground.

Here, the second switch unit 312 includes a second switch SW _33a which is a main switch of the second switch unit 312 and a second switch SW _{33b which} is an auxiliary means to assist the main switch.

Here, the fourth switch unit 314 includes a fourth switch SW _34a which is a main switch of the fourth switch unit 314 and a fourth switch SW _{34b which} is an auxiliary means for assisting the main switch.

The controller 320 includes a comparator 321 and an oscillator 322.

In addition, the charge pump circuit according to the first embodiment of the present invention further includes a first resistor R ₃₁ , a second resistor R ₃₂ , an output capacitor C _OUT , and a load current source I _LOAD .

<Connection>

The one end 1a of the switch (SW _31a) is applied to the input voltage (V _IN), the other end 1a of the switch (SW _31a) is coupled to the first node (①).

The end 1b of the switch (SW _31b) is applied to the input voltage (V _IN), the other end 1b of the switch (SW _31b) is coupled to the first node (①).

One end of the 3a switch SW _32a is grounded and the other end of the 3a switch SW _32a is connected to the second node ②.

One end of the third b switch SW _32b is grounded, and the other end of the third b switch SW _32b is connected to the second node ②.

One end of the second a switch SW _33a is grounded, and the other end of the second a switch SW _33a is connected to the first node ①.

One end of the second b switch SW _33b is grounded, and the other end of the second b switch SW _33b is connected to the first node ①.

One end of the fourth switch SW _34a is connected to the third node ③, and the other end of the fourth switch SW _34a is connected to the second node ②.

One end of the fourth switch SW _34b is connected to the third node ③, and the other end of the fourth switch SW _34b is connected to the second node ②.

One end of the charge capacitor (C _flying) is connected to a first node (①), the other end of the charge capacitor (C _flying) is coupled to a second node (②).

One end of the first resistor R ₃₁ is connected to the third node ③, and the other end of the first resistor R ₃₁ is connected to the fourth node ④.

One end of the second resistor R ₃₂ is applied with a reference voltage V _REF , and the other end of the second resistor R ₃₂ is connected to the fourth node ④.

One end of the output capacitor (C _OUT) is coupled to the third node (③), the other end of the output capacitor (C _OUT) is grounded.

The positive input terminal of the comparator 321 is connected to the fourth node ④, the negative input terminal of the comparator 321 is grounded, and the output terminal of the comparator 321 is connected to the input terminal of the oscillator 322.

The load current source I _LOAD is connected to the third node ③.

<Description>

The voltage of the fourth node ④ according to the ratio of the first resistor R ₃₁ and the second resistor R ₃₂ between the output voltage V _OUT applied to the third node ③ and the reference voltage V _REF is It is applied to the positive input terminal of the comparator 321.

The comparator 321 compares the voltage difference applied to the (-) input terminal and the (+) input terminal, and applies an output having a predetermined magnitude by the compared difference to the input terminal of the oscillator 322 through the output terminal.

Oscillator 322 oscillates in the control signal (Signal _control1, Signal _control2) as corresponding to the voltage difference supplied from the comparator 321, the predetermined frequency.

The first control switch SW _31a , the first switch SW _31b , the third switch SW _32a and the third switch SW _32b are switched by the first control signal Signalcontrol1 oscillated by the oscillator 322. The second a switch SW _33a , the second b switch SW _33b , the fourth a switch SW _34a , and the fourth b switch SW _34b are switched by the second control signal Signalcontrol2 oscillated by the oscillator 322. do.

That is, when the first control signal Signalcontrol1 oscillated by the oscillator 322 is a 'HIGH' or 'ON' signal, the first switch SW _31a , the first switch SW _31b , and the third switch SW _{32a are used.} ) And the third switch SW _32b are short-circuited to charge the input voltage VIN to the charging capacitor Cflying.

Here, the second control signal Signalcontrol2 oscillated by the oscillator 322 is a 'LOW' or 'OFF' signal is the second switch SW _33a , the second b switch SW _33b , the fourth a switch SW _34a and It is applied to the fourth switch SW _34b so as not to configure the circuit.

The oscillated first control signal Signalcontrol1 of the oscillator 322 is changed to a 'LOW' or 'OFF' signal such that the first switch SW _31a , the first b switch SW _31b , the third a switch SW _32a and At the same time that the 3b switch SW _32b is opened, the second control signal Signalcontrol2 oscillated by the oscillator 322 has a 'HIGH' or 'ON' signal as the 2a switch SW _33a and the 2b switch SW _33b. ), The 4a switch SW _34a and the 4b switch SW _34b are applied to form a circuit, and the input voltage VIN charged in the charging capacitor is discharged, and the phase is inverted by the output capacitor COUT. Is charged.

Load current source (I _LOAD) that supply sufficient current to the rises and increase the frequency of the comparator 321 is to detect this control signal (Signal _control1, Signal _control2) of the oscillator 322, the increased load current source (I _LOAD) Can be.

In contrast, the load when the current source (I _LOAD) decreases the comparator 321 is reduced to detects the power (P _CONV.LOSS) consumed to decrease the frequency of the control signal (Signal _control1, Signal _control2) of the oscillator (322) .

Here, the power consumption is expressed by the following equation.

Where P _{CONV .LOSS} is the power consumed.

Where C _flying is the charge capacitor capacity.

Where C _OUT is the output capacitor capacitance.

Where V _IN is the input voltage.

Here, V _OUT is an output voltage applied to the third node ③.

Here, V _ripple is the ripple voltage of the control signal (Signal _control1, Signal _control2).

Here, f _osc is the frequency of the control signal (Signal _control1, Signal _control2).

That is, the power consumption (P _{CONV .LOSS} ) is proportional to frequency as shown in Equation 1.

However, when decreasing the frequency of the control signal (Signal _control1, Signal _control2) for switching the oscillator 322 has a ripple may occur in the output voltage.

Here, the frequency f _osc and the ripple voltage V _ripple are expressed by the following equation.

Where V _ripple is the ripple voltage.

Where I _LOAD is the load current source.

Here, f _osc is the frequency of the control signal (Signal _control1, Signal _control2).

Where C _OUT is the output capacitor capacitance.

Where ESR _Cout is the equivalent series resistance (ESR) of the output capacitor.

That is, as shown in Equation 2, the ripple voltage V _ripple is inversely related to the frequency f _osc , and as the frequency f _osc decreases, the ripple voltage V _ripple increases.

By this structure, the efficiency of the DC-DC charge pump circuit can be improved.

In addition, when the switching resistance of the first switch portion 311, the second switch portion 312, the third switch portion 313 and the fourth switch portion 314 of the pump circuit portion 310 is reduced, the efficiency is further increased. .

That is, in the first switch unit 311, the first switch SW _31a and the first b switch SW _31b are configured in parallel to reduce the resistance of the first switch unit 311. This increases the output power.

Here, when the load current source I _LOAD is small, the parasitic capacitance generated in the first switch unit 311 may be reduced by opening the first b switches SW _31b connected in parallel to reduce power consumption.

In addition, when the size of the load current source I _LOAD is small, the respective auxiliary means of the charging switch unit 310a and the discharge switch unit 310b are independently switched to increase efficiency, and as shown in Equation 2 Since the switching resistance of the first switch unit 311 is independent of the ripple voltage V _ripple , the efficiency is further increased.

Those skilled in the art will appreciate that the same principle applies to the second switch portion 312, the third switch portion 313, and the fourth switch portion 314.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the exemplary embodiments described above are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the following claims rather than the detailed description, and the meaning and scope of the claims are as follows. And all changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

According to the configuration of the present invention described above, high efficiency is possible according to the size of the load in the charge pump circuit.

Claims (6)

Charge capacitors; A comparator configured to output an output signal according to a difference between voltages supplied to the plurality of input terminals; An oscillator receiving the output signal and outputting a first control signal and a second control signal; A charging switch unit configured to charge the charging capacitor by switching according to the first control signal; Auxiliary means connected in parallel with the charging switch unit; A discharge switch unit configured to discharge the charging capacitor by switching according to the second control signal; Auxiliary means connected in parallel with the discharge switch unit; And An output capacitor forming an output voltage according to an operation of the discharge switching unit Charge pump circuit comprising a. The method of claim 1, And an auxiliary means connected to the charging switch part and an auxiliary means connected to the discharge switch part are switching means. The method of claim 2, And an auxiliary means connected to the charging switch unit and an auxiliary means connected to the discharge switch unit are any one of a switch and a transistor. delete The method of claim 1, And the auxiliary means for the charging switch unit and the auxiliary means for the discharge switch unit have a structure capable of independently switching. The method of claim 1, And the auxiliary means connected with the charging switch unit is opened when the load current due to the output voltage is small.

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