KR101809099B1 - DC-DC converter and display device including the same - Google Patents

Abstract

The present invention provides a semiconductor device comprising: a switch; And a protection circuit part for reducing the loss of the switch, wherein the protection circuit part includes first and second capacitors and first to third diodes, and a first electrode of the first capacitor is connected to the first diode A second electrode of the second capacitor is connected to a second electrode of the second diode and a first electrode of the third diode, and the first electrode of the second capacitor is connected to the first electrode of the second diode, The first electrode of the diode is connected to the drain electrode of the switch, the second electrode of the first diode is connected to the first electrode of the second diode, and the second electrode of the second diode is connected to the drain electrode of the third diode And a DC-DC converter connected to the first electrode.

Description

DC-DC converter and a display device including the DC-DC converter and display device,

The present invention relates to a DC-DC converter, and more particularly, to a DC-DC converter and a display device including the DC-DC converter.

2. Description of the Related Art [0002] With the development of an information society, demands for a display device for displaying images have been increasing in various forms. Recently, a liquid crystal display (LCD), a plasma display panel (PDP) Various flat display devices such as an organic light emitting diode (OLED) have been utilized.

These flat panel display devices include a DC-DC converter to stably supply a voltage for driving the display panel and various driving parts.

In this case, the conventional DC-DC converter has a problem in that switching loss occurs due to the overlapping of voltage and current when the switch is turned on and off, and further, the switching loss is proportionally increased when operating at a high driving frequency.

In addition, the increase of the driving frequency as described above causes a problem of interference between electronic devices caused by a change amount of current (di / dt) and a change amount of voltage (dv / dt).

There is a problem in reducing the switching loss caused by the overlap of the voltage and the current in the switch at the time of turning on and off of the DC-DC converter operating at a high driving frequency.

There is also a challenge in reducing EMI effects.

According to an aspect of the present invention, And a protection circuit part for reducing the loss of the switch, wherein the protection circuit part includes first and second capacitors and first to third diodes, and a first electrode of the first capacitor is connected to the first diode A second electrode of the second capacitor is connected to a second electrode of the second diode and a first electrode of the third diode, and the first electrode of the second capacitor is connected to the first electrode of the second diode, The first electrode of the diode is connected to the drain electrode of the switch, the second electrode of the first diode is connected to the first electrode of the second diode, and the second electrode of the second diode is connected to the drain electrode of the third diode And a DC-DC converter connected to the first electrode.

The DC-DC converter further includes first and second inductors and an output capacitor, wherein the first inductor and the second inductor are connected to each other to constitute an auto-transformer, And a second electrode of the output capacitor is connected to a source electrode of the switch, and the second electrode of the output capacitor is connected to the drain electrode of the switch, and the second electrode of the output capacitor is connected to the source electrode of the switch. And the first electrode of the second capacitor is connected to the other side of the second inductor.

Wherein the first electrode of the fourth diode is connected to the other side of the second inductor and the second electrode of the second capacitor, and the second electrode of the fourth diode is connected to the second electrode of the second capacitor, A first electrode of the third capacitor and a second electrode of the third diode, and a second electrode of the third diode is connected to the first electrode of the third capacitor.

A flat panel display device comprising a display panel for displaying an image, comprising: a switch; and a protection circuit portion for reducing the loss of the switch, wherein the protection circuit portion includes first and second capacitors, Wherein the first electrode of the first capacitor is connected to the second electrode of the first diode and the first electrode of the second diode and the second electrode of the second capacitor is connected to the second electrode of the second diode, A first electrode of the first diode is connected to a drain electrode of the switch, a second electrode of the first diode is connected to a first electrode of the second diode, And a second electrode of the second diode is connected to the first electrode of the third diode.

The DC-DC converter further includes first and second inductors and an output capacitor, wherein the first inductor and the second inductor are connected to each other to constitute an auto-transformer, And a second electrode of the output capacitor is connected to a source electrode of the switch, and the second electrode of the output capacitor is connected to the drain electrode of the switch, and the second electrode of the output capacitor is connected to the source electrode of the switch. And the first electrode of the second capacitor is connected to the other side of the second inductor.

Wherein the first electrode of the fourth diode is connected to the other side of the second inductor and the second electrode of the second capacitor, and the second electrode of the fourth diode is connected to the second electrode of the second capacitor, A first electrode of the third capacitor and a second electrode of the third diode, and a second electrode of the third diode is connected to the first electrode of the third capacitor.

There is an effect that the switching loss caused by the overlap of the voltage and the current in the switch at the time of turning on and off of the DC-DC converter operating at a high driving frequency can be reduced.

It also has the effect of reducing EMI effects.

1 is a schematic cross-sectional view illustrating a flat panel display device according to an embodiment of the present invention.
2 is an equivalent circuit diagram of a pixel according to an embodiment of the present invention.
3 is a schematic cross-sectional view of a DC-DC converter according to an embodiment of the present invention.
4 is a schematic cross-sectional view showing a duty ratio;
5 and 6 are cross-sectional views schematically showing the types of DC-DC converters.
7 is a cross-sectional view schematically showing a circuit of a DC-DC converter according to an embodiment of the present invention;
8 is a circuit diagram of a DC-DC converter according to an embodiment of the present invention when the DC-DC converter is turned on.
9 is a circuit diagram showing the operation of the DC-DC converter according to the embodiment of the present invention when the DC-DC converter is turned off.
10 is a waveform diagram of voltage and current applied to the switch when the DC-DC converter is turned on and off;
11 is a result of driving simulation of a general DC-DC converter.
12 is a simulation result of the drive of the DC-DC converter according to the embodiment of the present invention.

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

FIG. 1 is a schematic view of a flat panel display according to an embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of a pixel according to an embodiment of the present invention.

First, for convenience of explanation, the liquid crystal display 100 of the flat panel display device 100 will be described as an example.

As shown in the figure, the liquid crystal display 100 according to the embodiment of the present invention includes a display panel 200 and a driving circuit unit 300.

In the display panel 200, a plurality of gate lines GL extend in the row direction in the first direction, for example. A plurality of data lines DL extend in a second direction that crosses the first direction, for example, in the column direction. The plurality of gate lines GL and the plurality of data lines DL intersecting each other define a plurality of pixels P arranged in a matrix form.

Referring to FIG. 2, each pixel P includes a thin film transistor T, a pixel electrode, a common electrode, a liquid crystal capacitor Clc, and a storage capacitor Cst.

The thin film transistor T is formed at the intersection of the gate line GL and the data line DL. The thin film transistor T is connected to the pixel electrode. On the other hand, a common electrode is formed corresponding to the pixel electrode. When a data voltage is applied to the pixel electrode and a common voltage is applied to the common electrode, an electric field is formed therebetween to drive the liquid crystal. The pixel electrode, the common electrode, and the liquid crystal located between these electrodes constitute a liquid crystal capacitor Clc. Each pixel P further includes a storage capacitor Cst, which serves to store the data voltage applied to the pixel electrode until the next frame.

Each pixel P may be composed of R, G, and B subpixels displaying red, green, and blue, for example. That is, the neighboring R, G, and B sub-pixels constitute a pixel that is a unit of image display.

The backlight 800 functions to supply light to the liquid crystal panel 200. As the backlight 800, a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED), or the like may be used.

The driving circuit portion D may include a timing control portion 300, a gate driving portion 400, a data driving portion 500, a power generating portion 600, and a gamma voltage supplying portion 700.

Here, the timing controller 300 receives a video data signal RGB, a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a clock signal CLK, and a data enable signal from an external system such as a TV system or a video card And receives a control signal TCS such as a signal DE. Although not shown, these signals may be input through the interface configured in the timing controller 300. [

The timing control unit 300 uses the input control signal TCS to control the gate control signal GCS for controlling the gate driving unit 400 and the data control signal DCS for controlling the data driving unit 500 . The gate control signal GCS includes a gate start pulse GSP, a gate shift clock GSC and a gate output enable signal GOE.

The data control signal DCS includes a source start pulse (SSP), a source sampling clock (SSC), a source output enable (SOE) signal, a polarity signal (POL) . ≪ / RTI >

The gate shift clock GSP serves to inform the start line of the screen in one vertical direction and the gate shift clock GSC is used to indicate the start line of the screen in the vertical direction, (T in Fig. 2) is turned on. In addition, the gate output enable signal GOE serves to control the output of the gate driver 400.

The source start pulse SSP serves to notify the start point of data in the horizontal direction, that is, the first pixel P, and the source sampling clock SSC latches the data based on the rising and falling edges. (not shown). The polarity signal POL controls the data voltage of the display panel 200 to be a positive polarity or a negative polarity, ) It is a signal that tells the polarity to drive with polarity.

In addition, the timing controller 300 receives the image data signals RGB from the external system, aligns them, and transmits the image data signals to the data driver 500.

The data driver 500 supplies the data voltages to the plurality of data lines DL in response to the data control signal DCS and the video data RGB supplied from the timing controller 300. [ That is, the gamma voltage Vgamma is used to generate, for example, a data voltage corresponding to the image data signal RGB and output the generated data voltage to the data line DL.

The gate driver 400 sequentially scans a plurality of gate lines GL in response to a gate control signal GCS supplied from the timing controller 300. For example, a plurality of gate lines GL are sequentially selected for every frame, and a gate voltage is output to the selected gate line GL. By the gate voltage, the thin film transistor T located on the corresponding row line is turned on. On the other hand, a turn-off voltage is supplied to the gate line GL until the scan of the next frame, and the thin film transistor T maintains the turn-off state.

The gamma voltage supplier 700 divides the high potential common voltage and the low potential common voltage generated from the power generator 600 to generate the gamma voltage Vgamma and supplies the generated gamma voltage Vgamma to the data driver 500.

The power generating unit 600 generates various driving voltages required for driving the flat panel display device 100. For example, a power supply voltage supplied to the timing controller 300, the data driver 500 and the gate driver 400, a gate high voltage and a gate low voltage supplied to the gate driver 400, and the like.

The flat panel display 100 may use a plurality of DC-DC converters in the display panel 200, the driving circuit portion D, and the like.

Hereinafter, a DC-DC converter according to an embodiment of the present invention will be described in detail with reference to FIG.

3 is a view schematically showing a DC-DC converter according to an embodiment of the present invention.

3, the DC-DC converter 910 may be connected to the PWM controller 920. [

Here, the PWM control unit 920 generates a pulse width modulation (PWM) control signal PWM and outputs it to the DC-DC converter 910.

The PWM control signal PWM is a square wave signal for adjusting the duty ratio of the on time and the off time of the DC-DC converter 910. Therefore, the on-time of the DC-DC converter 910 is adjusted in accordance with the on-off duty width of the PWM control signal PWM. That is, by adjusting the duty ratio of the PWM control signal PWM, the level of the output voltage Vout of the DC-DC converter 910 can be adjusted to the target voltage level.

More specifically, referring to FIG. 4, the duty ratio D can be expressed by Equation (1). FIG. 4 is a diagram showing the output voltage Vout according to the duty ratio D; FIG.

D = Ton / T (Ton: time when the switching element is turned on, T: switching period of the switching element)

Therefore, when the output voltage is Vout (A), the duty ratio D becomes larger when the output voltage is Vout (A) because the on period is larger than that when the output voltage is Vout (B).

Hereinafter, the DC-DC converter 910 according to the embodiment of the present invention will be described in more detail with reference to FIGS. 5 and 7. FIG.

5 and 6 are diagrams schematically showing circuits of various types of DC-DC converters, and FIG. 7 is a circuit diagram of a DC-DC converter according to an embodiment of the present invention.

First, the DC-DC converter 910 receives a power supply voltage supplied from the outside as an input voltage Vin, and generates and outputs the output voltage Vout to a desired level.

5, a DC-DC converter 910 is provided with a buck (step-down) (FIG. 5A), a boost (step-up) 5 (b)), a buck-boost converter (Fig. 5 (c)), and the like.

The buck converter (step-down converter) is a converter in which the output voltage Vout is output lower than the input voltage Vin. At this time, the output voltage Vout is expressed by Equation (2).

(2): Output voltage (Vout) = D * Input voltage (Vin).

The boost converter (step-up converter) is a converter in which the output voltage Vout is output higher than the input voltage Vin. At this time, the output voltage Vout is expressed by Equation (3).

(3): Output voltage (Vout) = (1 / (1-D)) * Input voltage (Vin).

The buck-boost converter is a mixture of a buck converter and a boost converter. At this time, the output voltage (Vout) is expressed by Equation (4).

(4): Output voltage (Vout) = (D / (1-D)) * Input voltage (Vin).

As another kind of the DC-DC converter 910, there is a boost converter using an autotransformer.

An auto transformer refers to a transformer in which the first and second coil lines are not separated from each other and a part thereof is commonly used.

Fig. 6 is a view schematically showing a circuit of a converter in which an auto-transformer is coupled to a boost converter (see Fig. 5 (b)).

At this time, the relationship between the input voltage Vin and the output voltage Vout is expressed by Equation (5).

(5): Output voltage Vout = (sqrt (L4 / L3) * (1 / (1-D)) * Input voltage Vin.

Here, L4 is the fourth inductor in Fig. 6, and L2 is the third inductor in Fig. The third inductor L3 and the fourth inductor L4 constitute an auto transformer.

That is, the converter circuit combining the auto transformer can adjust the step-up ratio by adjusting the turn ratio of the third inductor L3 and the fourth inductor L4, and thus various designs can be performed. Here, the step-up ratio can be expressed by the output voltage Vout / the input voltage Vin.

The DC-DC converter 910 according to the embodiment of the present invention will now be described in more detail with reference to FIG.

As shown in FIG. 7, the DC-DC converter 910 according to the embodiment of the present invention may further include a protection circuit portion 911 in the DC-DC converter using the above-described auto transformer.

Specifically, the DC-DC converter 910 according to the embodiment of the present invention includes first and second inductors L1 and L2, an output capacitor Coss, and first to third capacitors C1, C2, C3, a first to fourth diodes D1, D2, D3, D4, and a switch M, respectively.

Here, the first to third diodes D1, D2, and D3 and the first and second capacitors C1 and C2 constitute a protection circuit portion 911. [

First, the connection relationship of the DC-DC converter 910 according to the embodiment of the present invention will be described.

One terminal (+) of the input voltage Vin is connected to one side of the first inductor L1. The other side of the first inductor L1 is connected to one side of the second inductor L2 and the input terminal of the switch M for example a drain electrode D and a first electrode of the output capacitor Coss, For example, an anode electrode of the first electrode D1.

One end of the second inductor L2 is connected to the input terminal of the switch M, for example, a drain electrode D, a first electrode of the output capacitor Coss, and a first electrode of the first diode D1, Electrode. The other side of the second inductor L2 is connected to the first electrode of the second capacitor C2 and the first electrode of the fourth diode D4, for example, the anode electrode.

Here, the first inductor L1 and the second inductor L2 constitute an auto transformer (AT). As described above, the autotransformer (AT) refers to a transformer in which the first and second coil lines are not separated from each other, and a part of them is commonly used. Here, a part of the first inductor L1 is an example And a part of the second inductor L2 may serve as a secondary coil line, for example.

Therefore, by adjusting the turns ratio of the first inductor L1 and the second inductor L2, the step-up ratio can be adjusted, and various step-up ratio can be designed.

The input terminal of the switch M is connected to the first electrode of the output capacitor Coss and the anode electrode of the first diode D1, for example. The output terminal of the switch M, for example, the source electrode S is connected to one terminal (-) of the input voltage Vin, the second electrode of the output capacitor Coss, the second electrode of the first capacitor C1, The second electrode of the third capacitor C3, and the output terminal of the output voltage Vout.

The gate electrode G of the switch M is connected to the PWM control unit 920 to receive the PWM control signal PWM. Thus, the switch M is turned on / off in accordance with the duty ratio of the PWM control signal PWM.

Here, the switch M may be, for example, a bipolar junction transistor (BJT) or a metal oxide silicon field effect transistor (MOSFET), which is a majority carrier semiconductor device. It will be apparent to those skilled in the art that other types of transistors may be used.

The first electrode of the output capacitor Coss is connected to the anode electrode of the first diode D1. The second electrode of the output capacitor Coss is connected to the second electrode of the first capacitor C1, the second electrode of the third capacitor C3 and the output terminal of the output voltage Vout.

The first electrode of the first capacitor C1 is connected to the second electrode of the first diode D1, for example, a cathode electrode and the first electrode of the second diode D2, for example, the anode electrode. The second electrode of the first capacitor C1 is connected to the second electrode of the third capacitor C3 and the output terminal of the output voltage Vout.

The first electrode of the second capacitor C2 is connected to the first electrode of the fourth diode D4, for example, the anode electrode. The second electrode of the second capacitor C2 is connected to the second electrode of the second diode D2, for example, the cathode electrode and the first electrode of the third diode D3, for example, the anode electrode.

The first electrode of the third capacitor C3 is connected to the second electrode of the third and fourth diodes D3 and D4, for example, the cathode electrode and the output terminal of the output voltage Vout. The second electrode of the third capacitor C3 is connected to the output terminal of the output voltage Vout.

The second electrode of the first diode D1, for example, the cathode electrode is connected to the first electrode of the second diode D2, for example, the anode electrode.

The second electrode of the second diode D2 is connected to the first electrode of the third diode D3.

The second electrode of the third diode D3 is connected to the second electrode of the fourth diode D4.

Although not shown, the output terminal of the switch M and the output capacitor Coss and the second electrodes of the first and third capacitors C1 and C3 can be grounded.

Here, the fourth diode D4 sends the input charge and the input voltage Vin to the output terminal of the output voltage Vout.

The third capacitor (C3) stabilizes by removing the ripple component of the output voltage (Vout) of the output stage. That is, the ripple component is included in the output voltage Vout in which the input voltage Vin is boosted by the high-speed switching of the switch M, and this ripple component is removed.

8 and 9, the operation mode of the DC-DC converter 910 according to the embodiment of the present invention will be described.

Fig. 8 is an operational circuit diagram when the switch M is turned on, and Fig. 9 is an operational circuit diagram when the switch M is turned off.

First, the first mode is a mode in which the switch M is turned on.

8, when the switch M is turned on, the current flows through the first inductor L1 and the switch M, and the first inductor L1 is connected to the first inductor L1, Energy is stored.

When the switch M is turned off, the energy stored in the first capacitor C1 passes through the second diode D2 and is transmitted to the second capacitor C2. Accordingly, the second capacitor C2 ) Is charged with energy.

The second mode is a mode in which the switch M is turned off.

9, when the switch M is turned off, the current does not pass through the switch M, but charges the first capacitor C1 through the output capacitor Coss and the first diode D1 do.

At this time, as the supply of the current from the first capacitor C1 is stopped, the second capacitor C2 discharges the energy received from the first capacitor C1 in the first mode.

Also, the energy stored in the first inductor L1 is transferred to the second inductor L2. As described above, the first inductor L1 and the second inductor L2 form an automatic transformer (AT). The first inductor L1 and the second inductor L2 are connected to each other according to the winding ratio of the first inductor L1 and the second inductor L2. The voltage Vin is boosted. Further, the boosted input voltage Vin is output as the output voltage Vout through the fourth diode D4.

At this time, the current flowing in the second inductor L2 is reduced to zero. The sum of the input voltage Vin and the output voltage Vout is applied between the drain electrode D and the source electrode S of the switch M. [ That is, to the output capacitor Coss.

The third mode is a mode in which the switch M is turned on.

Referring again to FIG. 8, energy is stored in the first inductor L1. Also, the energy charged in the first capacitor C1 is transmitted to the second capacitor C2 through the second diode D2.

Here, the effect of the DC-DC converter 910 according to the embodiment of the present invention will be described in more detail.

10 is a diagram showing the voltage-current waveform of the switch M in the absence of the protection circuit portion 911. FIG.

10, when the switch M is turned off, the voltage of the switch M is charged with a predetermined slope, and the current also decreases with a predetermined slope. On the other hand, when the switch M is turned on, the voltage of the switch M is discharged with a predetermined slope, and the current increases with a predetermined slope.

At this time, an overlap of the voltage and the current causes the conduction loss of the switch M, overvoltage and overcurrent stress. In addition, the overlapping part appears as a switching loss due to hard switching. Also, EMI (electro-magnetic interference) phenomenon occurs.

Here, when the switch M is turned on, a method of reducing the switching loss by the protection circuit portion 911 is as follows.

First, as described above, a switching loss occurs due to an overvoltage and an overcurrent when the switch M is turned on. Specifically, a loss of (1/2) * Coss * V 손실 is caused by the output capacitor Coss. Here, Coss refers to the voltage of the output capacitor (Coss), and n can be, for example, 2 as a natural number.

At this time, when the current flowing through the second inductor L2 becomes zero, since the voltage of the output capacitor Coss is higher than the input voltage Vin (because the input voltage Vin and the output voltage Vout ) Is applied to the output capacitor Coss and the output voltage Vout has an amplitude of about the input voltage Vin due to the resonance of the first inductor L1 and the output capacitor Coss Resonance. Here, when the gate signal is applied to the gate electrode G of the switch M when the voltage of the output capacitor Coss is minimized, the switching loss becomes close to zero.

When the switch M is turned off, a method of reducing the switching loss by the protection circuit portion 911 is as follows.

First, as described above, a switching loss occurs due to overvoltage and overcurrent when the switch M is turned off.

At this time, when the switch M is turned off, the current delivered to the drain electrode D of the switch M is transferred to the output capacitor Coss and also to the first capacitor C1. As a result, the overcurrent of the drain electrode (D) of the switch (M) can be prevented, and the switching loss can be improved.

11 is a simulation result when a DC-DC converter using a general auto transformer is driven, and FIG. 12 is a simulation result when the DC-DC converter 910 is driven according to an embodiment of the present invention.

As shown in FIG. 11 and FIG. 12, it can be seen that the DC-DC converter 910 according to the embodiment of the present invention is lower in power loss than a general DC-DC converter.

It can also be seen that the abrupt changes in voltage and current are improved.

As described above, the DC-DC converter 910 according to the embodiment of the present invention further includes the protection circuit portion 911, thereby preventing overvoltage and overcurrent of the switch M, thereby improving the switching loss. As a result, EMI characteristics are also improved.

The embodiment of the present invention described above is an example of the present invention, and variations are possible within the spirit of the present invention. Accordingly, the invention includes modifications of the invention within the scope of the appended claims and equivalents thereof.

100: Flat panel display device 200: Display panel
910: DC-DC converter 911: Protection circuit
D: Diode C: Capacitor L: Inductor
Vin: input voltage Vout: output voltage

Claims (6)

A switch;
A protection circuit part for reducing the loss of the switch;
First and second inductors;
An output capacitor;
A third capacitor and a fourth diode,
The protection circuit unit includes:
First and second capacitors, and first to third diodes,
A first electrode of the first capacitor is connected to a second electrode of the first diode and a first electrode of the second diode,
The second electrode of the second capacitor is connected to the second electrode of the second diode and the first electrode of the third diode,
A first electrode of the first diode is connected to a drain electrode of the switch, a second electrode of the first diode is connected to a first electrode of the second diode,
The second electrode of the second diode is connected to the first electrode of the third diode,
The first inductor and the second inductor are connected to each other at one side to constitute an auto transformer,
The first electrode of the output capacitor is connected to one side of the first inductor, one side of the second inductor, the drain electrode of the switch, and the first electrode of the first diode, and the second electrode of the output capacitor Connected to the source electrode of the switch,
A first electrode of the second capacitor is connected to the other side of the second inductor,
The other side of the first inductor is connected to the positive terminal of the input voltage and the other side of the second inductor is connected to the first electrode of the fourth diode of the output voltage,
The first electrode of the fourth diode is connected to the other side of the second inductor and the first electrode of the second capacitor, the second electrode of the fourth diode is connected to the first electrode of the third capacitor, 3 < / RTI > diode,
The second electrode of the third diode is connected to the first electrode of the third capacitor
DC-DC converter.

delete The method according to claim 1,
When the switch is turned on, the switch is turned on when the voltage of the output capacitor is at a minimum
DC-DC converter.
A flat panel display comprising a display panel for displaying an image,
A switch, a protection circuit for reducing the loss of the switch, first and second inductors, an output capacitor, a third capacitor and a fourth diode,
The protection circuit unit includes:
First and second capacitors, and first to third diodes,
A first electrode of the first capacitor is connected to a second electrode of the first diode and a first electrode of the second diode,
The second electrode of the second capacitor is connected to the second electrode of the second diode and the first electrode of the third diode,
A first electrode of the first diode is connected to a drain electrode of the switch, a second electrode of the first diode is connected to a first electrode of the second diode,
The second electrode of the second diode is connected to the first electrode of the third diode,
The first inductor and the second inductor are connected to each other at one side to constitute an auto transformer,
The first electrode of the output capacitor is connected to one side of the first inductor, one side of the second inductor, the drain electrode of the switch, and the first electrode of the first diode, and the second electrode of the output capacitor Connected to the source electrode of the switch,
A first electrode of the second capacitor is connected to the other side of the second inductor,
The other side of the first inductor is connected to the positive terminal of the input voltage and the other side of the second inductor is connected to the first electrode of the fourth diode of the output voltage,
The first electrode of the fourth diode is connected to the other side of the second inductor and the first electrode of the second capacitor, the second electrode of the fourth diode is connected to the first electrode of the third capacitor, 3 < / RTI > diode,
The second electrode of the third diode is connected to the first electrode of the third capacitor
A flat panel display comprising a DC-DC converter.

delete 5. The method of claim 4,
When the switch is turned on, the switch is turned on when the voltage of the output capacitor is at a minimum
A flat panel display comprising a DC-DC converter.

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