TW201810903A - Power switching circuit allowing a first current to flow to the load via the first controller and a second current to flow to the load via the second controller - Google Patents

Abstract

A power switching circuit adapted to be electrically connected to a load includes a first controller, a second controller, and a comparator. The first controller converts a first voltage into a driving voltage, outputs the same to the load, and allows a first current to flow to the load via the first controller itself. The second controller includes a first end, a second end, and a control end. The comparator generates a control signal according to a magnitude relationship between a threshold voltage and the driving voltage. The control end of the second controller receives the control signal to control the conduction between the first end and the second end. When the first end and the second end are conducted, the second controller converts a second voltage into the driving voltage, outputs the same to the load and allows a second current to flow to the load via the second controller itself.

Description

Power switching circuit

The present invention relates to a switching circuit, and more particularly to a power switching circuit for supplying power to a load.

In today's 3C industry, many electronic products are often equipped with display panels for displaying various messages. Common display panels have a large number of pixels arranged in a matrix. The so-called "Display Driver Integration" (DDI) The circuit is often packaged in a display panel driver IC for driving the display panel, that is, providing power to the pixels in the display panel.

The "resolution" of a display panel is related to the number of such pixels. The higher the resolution, the more the number of these pixels, and the better the screen effect of the display panel. With the advancement and development of technology, The display panel continues to develop to higher resolutions. However, the higher the resolution of the display panel, the greater the power required to drive the display panel. Therefore, how to improve the performance of the display panel while considering environmental protection and energy saving, It has become one of the important issues when designing display drive integrated circuits.

Referring to FIG. 1, a conventional display panel driving unit 91 receives a first voltage IOVCC from a first power source of a system unit 92 and a second voltage VCI from a second power source. The display panel driving unit 91 is internal A voltage conversion circuit is provided. The voltage conversion circuit can step down and convert the first voltage IOVCC and the second voltage VCI into a driving voltage VDDD. The display panel driving unit 91 drives a display panel 93 with the driving voltage VDDD. . For example, if the first voltage IOVCC is 1.8 volts, the second voltage VCI is 3 volts, and the driving voltage VDDD is 1.6 volts, the voltage conversion circuit of the display panel driving unit 91 uses a linear regulator (Linear regulator), which is used to step down an input voltage before outputting it. The larger the step-down voltage of the voltage conversion circuit, the worse the step-down conversion efficiency. According to the value of the previous example, the second voltage VCI is reduced. The conversion to the driving voltage VDDD requires a step down of 1.4 volts, and the conversion of the first voltage IOVCC to the driving voltage VDDD only requires a step down of 0.2 volts, so the conversion efficiency of converting the second voltage VCI to the driving voltage VDDD will be worse than that The first voltage IOVCC is converted to the efficiency of the driving voltage VDDD. However, a second maximum current I2max that the second power source can provide is greater than a first maximum current I1max that the first power source can provide. The power source can provide The larger the maximum current is, the more energy can be provided to the load, so the second power source has better driving capability than the first power source. That is, the conversion efficiency of the first power source is good, but the driving capability is weak, while the conversion efficiency of the second power source is poor, but the driving capability is strong, and when the display panel 93 requires a large amount of power, The first power supply cannot provide sufficient driving capability, so the second power supply must be powered simultaneously with the first power supply, and the second power supply will drag the overall conversion efficiency, so there are still obvious shortcomings.

Therefore, an object of the present invention is to provide a power switching circuit capable of both driving ability and conversion efficiency.

Therefore, the power switching circuit of the present invention is suitable for being electrically connected between a first power source, a second power source, and an input connection terminal of a load to provide a driving voltage to the input connection terminal; the power switching circuit includes a A first controller, a second controller, and a second comparator; the first controller converts a first voltage from the first power source into the driving voltage and outputs it to the input connection terminal of the load, And allows a first current from the first power source to flow into the input connection terminal by itself; the second controller includes a first terminal electrically connected to the second power source, and a first terminal electrically connected to the input terminal of the load. Two terminals, and a second control terminal, the second control terminal receives a second control signal related to the driving voltage to control the conduction between the first terminal and the second terminal, when the first terminal and When the second terminal is conducting, the first terminal receives a second voltage from the second power source, the second controller converts the second voltage into the driving voltage and outputs the driving voltage to the second terminal, and allows One from the second electric The second current flows into the input connection terminal of the load through itself; the second comparator includes a second comparison output terminal electrically connected to the second control terminal of the second controller, and the second comparator is based on a second The magnitude relationship between the threshold voltage and the driving voltage generates the second control signal and outputs the second control signal.

In some embodiments, when the second comparator determines that the driving voltage is less than the second threshold voltage, the second control terminal of the second controller controls the first terminal and the second terminal according to the second control signal. Conduction between terminals.

In some embodiments, the first controller includes a first terminal electrically connected to the first power source, a second terminal electrically connected to an input connection terminal of the load, and a first control terminal, the first control terminal Receiving a first control signal related to the driving voltage to control conduction or non-conduction between the first end and the second end of the first controller; the power switching circuit further includes a first comparator, the first A comparator includes a first comparison output terminal electrically connected to a first control terminal of the first controller. The first comparator is based on a magnitude relationship between a first threshold voltage greater than the second threshold voltage and the driving voltage. Generating the first control signal and outputting it to the first comparison output terminal; when the first comparator judges that the driving voltage is greater than the first threshold voltage, the first control terminal of the first controller according to the first control signal Control the first terminal and the second terminal from conducting.

In some embodiments, the load is a display panel including a plurality of liquid crystal capacitors, and a driving current is allowed to flow into the input connection terminal to charge the liquid crystal capacitors, and the driving current is the first current or the The sum of the first current and the second current.

The effect of the present invention is that the second control signal is generated by the second comparator according to a magnitude relationship between a second threshold voltage and the driving voltage, and the second control terminal receives the second control signal to control the second control signal. The first end and the second end of the second controller are conductive or non-conductive, so that the second power source can participate in power supply only when the load requires a large amount of power, and has a better driving capability. When the load only needs a small amount of power, it is only powered by the first power source, and can have better conversion efficiency.

Referring to FIG. 2, an embodiment of a power switching circuit according to the present invention is suitable for being electrically connected between a first power source, a second power source, and an input connection terminal 51 of a load 5. The first power source has a first voltage. IOVCC can provide a first current I1, and the second power source has a second voltage VCI and can provide a second current I2. In this embodiment, the load 5 is, for example, a display panel, and includes a plurality of liquid crystal capacitors 52 (only one of which is shown in FIG. 2), but is not limited thereto. The first power supply and the second power supply The power source sequentially charges the liquid crystal capacitors 52 through the power switching circuit so that the display panel displays correct brightness. More specifically, the input connection terminal 51 of the load 5 receives a voltage IOVCC related to the first voltage. And the driving voltage VDDD of the second voltage VCI and allows a driving current Iload to flow into itself to charge the liquid crystal capacitors 52, and the driving current Iload is the first current I1 or the first current I1 and the first current Sum of two currents I2. In this embodiment, the first voltage IOVCC is, for example, 1.8 volts, the second voltage VCI is, for example, 3 volts, and the rated value of the driving voltage VDDD is, for example, 1.6 volts, but it is not limited thereto.

The power switching circuit includes a first controller 1, a first comparator 2, a second controller 3, and a second comparator 4.

The first controller 1 includes a first terminal 11 electrically connected to the first power source, a second terminal 12 electrically connected to the input connection terminal 51 of the load 5, and a first control terminal 13. The terminal 13 receives a first control signal VG1 related to the driving voltage VDDD to control conduction or non-conduction between the first terminal 11 and the second terminal 12 of the first controller 1. When the first terminal 11 and When the second terminals 12 are conducting, the first terminal 11 receives the first voltage IOVCC, the first controller 1 converts the first voltage IOVCC to the driving voltage VDDD and outputs the driving voltage VDDD to the second terminal 12, and The first current I1 is allowed to flow into the input connection terminal 51 of the load 5 through itself to charge the liquid crystal capacitor 52 of the load 5. In this embodiment, the first controller 1 is a P-type enhanced metal oxide semiconductor field effect transistor (Enhancement Type Metal-Oxide-Semiconductor Field-Effect Transistor), and is operated in a saturation region ( Saturation Region), a voltage difference is formed between the first terminal 11 and the second terminal 12, and the voltage difference is equal to the difference between the first voltage IOVCC and the driving voltage VDDD.

The first comparator 2 includes a positive input terminal 21 electrically connected to the input connection terminal 51 of the load 5 to receive the driving voltage VDDD, a negative input terminal 22 accepted to input a first threshold voltage V1, and an electrical connection to the first A first comparison output terminal 23 of the first control terminal 13 of a controller 1, the first comparator 2 generates the first control signal VG1 according to a magnitude relationship between the first threshold voltage V1 and the driving voltage VDDD. And output the first control signal VG1 to the first comparison output terminal 23. Specifically, when the first comparator 2 determines that the driving voltage VDDD is less than the first threshold voltage V1, the first comparator 2 The generated first control signal VG1 causes the first control terminal 13 of the first controller 1 to control the conduction between the first terminal 11 and the second terminal 12, otherwise, when the first comparator 2 judges the driving When the voltage VDDD is greater than the first threshold voltage V1, the first control signal VG1 generated by the first comparator 2 causes the first control terminal 13 of the first controller 1 to control the first terminal 11 and the second terminal. 12 is not conducting.

In this embodiment, the first threshold voltage V1 is, for example, 1.65 volts, but is not limited thereto. When the driving voltage VDDD is lower than the first threshold voltage V1, the first comparator 2 is connected to the first The comparison output terminal 23 outputs a low-state voltage to make the first terminal 11 and the second terminal 12 of the first controller 1 conductive, and when the driving voltage VDDD is higher than the first threshold voltage V1, The first comparator 2 outputs a high-state voltage at the first comparison output terminal 23 so that the first terminal 11 and the second terminal 12 of the first controller 1 are not conducted. The supplementary explanation is: Unless the first power supply or the first controller 1 fails, the driving voltage VDDD should be kept below the first threshold voltage V1, that is, the function of the first comparator 2 is to be an overvoltage. The controller is protected from abnormally high voltage causing damage to the load 5.

The second controller 3 includes a first terminal 31 electrically connected to the second power source, a second terminal 32 electrically connected to the input connection terminal 51 of the load 5, and a second control terminal 33. The second control The terminal 33 receives a second control signal VG2 related to the driving voltage VDDD to control conduction or non-conduction between the first terminal 31 and the second terminal 32 of the second controller 3. When the first terminal 31 and When the second terminals 32 are conducting, the first terminal 31 receives the second voltage VCI, the second controller 3 converts the second voltage VCI into the driving voltage VDDD and outputs the driving voltage VDDD to the first The second terminal 32 allows the second current I2 to flow into the input connection terminal 51 of the load 5 through itself. Similarly, the second controller 3 is a P-type enhanced metal oxide semiconductor field effect transistor, and also operates in a saturation region when it is turned on, so a first terminal 31 and a second terminal 32 are formed. A voltage difference equal to a difference between the second voltage VCI and the driving voltage VDDD.

It is added that, in this embodiment, the first voltage IOVCC is 1.8 volts, the second voltage VCI is 3 volts, the driving voltage VDDD is 1.6 volts, and the first voltage IOVCC and the second voltage VCI are The first controller 1 and the second controller 3 are respectively stepped down to the driving voltage VDDD. Therefore, when the first controller 1 is turned on, the distance between the first terminal 11 and the second terminal 12 is reduced. The voltage difference is 0.2 volts (the voltage difference between the first voltage IOVCC and the driving voltage VDDD), and when the second controller 3 is turned on, the voltage difference across the first terminal 31 and the second terminal 32 is 1.4 volts (voltage difference between the second voltage VCI and the driving voltage VDDD). Therefore, assuming that the first controller 1 and the second controller 3 are both on and the first current I1 and the second current I2 are equal, The power consumed by the second controller 3 is seven times that of the first controller 1, so the conversion efficiency of the second power source is worse than that of the first power source.

The second comparator 4 includes a positive input terminal 41 electrically connected to the input connection terminal 51 of the load 5 to receive the driving voltage VDDD, a negative input terminal 42 received a second threshold voltage V2 input, and an electrical connection to the first The second control terminal 33 and the second comparison output terminal 43 of the two controllers 3, and the second comparator 4 generates the second control signal VG2 according to a magnitude relationship between the second threshold voltage V2 and the driving voltage VDDD, and The second control signal VG2 is output to the second comparison output terminal 43, that is, when the second comparator 4 determines that the driving voltage VDDD is less than the second threshold voltage V2, the second comparator 4 generates the The second control signal VG2 causes the second control terminal 33 of the second controller 3 to control the conduction between the first terminal 31 and the second terminal 32 of the second controller 3, otherwise, when the second comparator 4 When it is determined that the driving voltage VDDD is greater than the second threshold voltage V2, the second control signal VG2 generated by the second comparator 4 causes the second control terminal 33 of the second controller 3 to control the second controller 3 There is no conduction between the first end 31 and the second end 32.

In this embodiment, the second threshold voltage V2 is, for example, 1.58 volts, but is not limited thereto. When the driving voltage VDDD is lower than the second threshold voltage V2, the second comparator 4 is connected to the second threshold voltage V2. The comparison output terminal 43 outputs a low-state voltage, so that the first terminal 31 and the second terminal 32 of the second controller 3 are turned on. When the driving voltage VDDD is higher than the second threshold voltage V2, the first The two comparators 4 output a high-state voltage at the second comparison output terminal 43 to prevent the first terminal 31 and the second terminal 32 of the second controller 3 from conducting. Specifically, when the load 5 consumes a large amount of power and is in a heavy-load mode, the driving current Iload is large, and the driving voltage VDDD decreases as the driving current Iload increases, in other words, when the driving When the voltage VDDD drops below the second threshold voltage V2, it means that the load 5 is in a heavy-load mode and requires a large amount of power. Therefore, the second comparator 4 turns on the second controller 3 and makes the first The two power sources join the first power source to supply power to the load 5 to provide sufficient driving capacity for the load 5, and when the load 5 consumes only small power and is in a light load mode, the driving current Iload is small, so the When the driving voltage VDDD is maintained above the second threshold voltage V2, the second comparator 4 will make the second controller 3 non-conductive, so only the first power source supplies power to the load 5 to maintain better conversion Efficiency, while achieving energy saving effects.

It is added that, taking the load 5 connected in this embodiment as a display panel, the power consumed by the display panel is related to the displayed screen. For example, the first power source can provide the first The maximum value of a current I1 is set to, for example, 20 mA, which means that when the driving current Iload exceeds 20 mA, the driving voltage VDDD drops below the second threshold voltage V2, and the second controller 3 is turned on. With reference to FIG. 3, when the display panel displays a monochrome picture such as all white or all black, it is in a light load mode. At this time, the driving current Iload is, for example, less than 20 mA, so it can only be provided by the first power source. The electric energy required by the load 5 to obtain better conversion efficiency. When the display panel displays, for example, a checkerboard with a grid pattern and black and white interlacing, it is in a heavy-load mode. At this time, the driving current Iload is, for example, 50 mA, which has exceeded the first current I1 that the first power supply can provide. Therefore, in the heavy-load mode, the first power source and the second power source jointly supply power to provide sufficient driving capacity for the load 5, and at this time, the first current I1 is 20 mA, and the second The current I2 is 30mA. When the display panel displays a general screen such as a normal landscape or portrait, it is in a medium load mode. At this time, the magnitude of the driving current Iload is between the light load mode and the heavy load mode. If the driving current Iload is less than the maximum value of the first current I1, it is powered only by the first power source. If the driving current Iload is greater than the maximum value of the first current I1, the second power source is added to the first power source. The power is supplied together.

It should be noted that the above-mentioned voltage or current values are only intended to assist in understanding the operation mode of this embodiment, and are not intended to limit the scope of the present invention.

In summary, the power switching circuit of the present invention receives the driving voltage VDDD through the second comparator 4 and controls the second controller 3 to be turned on according to the magnitude relationship between the driving voltage VDDD and the second threshold voltage V2. Or not, it can determine whether the second power supply participates in supplying power to the load 5 or not. Therefore, when the load 5 is in a heavy load mode, the first power supply and the second power supply can supply power at the same time to provide sufficient driving capacity, When the load 5 is in the light load mode, it is only powered by the first power source to obtain better conversion efficiency, so it can indeed achieve the purpose of the present invention.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited in this way, any simple equivalent changes and modifications made in accordance with the scope of the patent application and the content of the patent specification of the present invention are still Within the scope of the invention patent.

1‧‧‧The first controller
11‧‧‧ the first end
12‧‧‧ the second end
13‧‧‧ the first control terminal
2‧‧‧first comparator
21‧‧‧ Positive input
22‧‧‧ negative input
23‧‧‧First comparison output
3‧‧‧second controller
31‧‧‧ the first end
32‧‧‧ the second end
33‧‧‧Second control terminal
4‧‧‧Second Comparator
41‧‧‧ Positive input
42‧‧‧ Negative input
43‧‧‧Second comparison output
5‧‧‧ load
51‧‧‧input connection
52‧‧‧LCD Capacitor
91‧‧‧display panel drive unit
92‧‧‧System Unit
93‧‧‧Display Panel
IOVCC‧‧‧First Voltage
VCI‧‧‧Second Voltage
VDDD‧‧‧Drive voltage
V1‧‧‧ first critical voltage
V2‧‧‧Second critical voltage
VG1‧‧‧first control signal
VG2‧‧‧Second control signal
Iload‧‧‧Drive current
I1max‧‧‧first maximum current
I2max‧‧‧Second maximum current
I1‧‧‧first current
I2‧‧‧second current

Other features and effects of the present invention will be clearly presented in the embodiment with reference to the drawings, in which: FIG. 1 is a circuit block diagram illustrating a conventional display panel driving unit electrically connected to a system unit and a display Between panels; FIG. 2 is a circuit diagram of an embodiment of a power switching circuit of the present invention electrically connected to a load; and FIG. 3 is an embodiment of this embodiment when electrically connected between a first power source, a second power source and the load, A bar graph related to a load current.

1‧‧‧The first controller

11‧‧‧ the first end

12‧‧‧ the second end

13‧‧‧ the first control terminal

2‧‧‧first comparator

21‧‧‧ Positive input

22‧‧‧ negative input

23‧‧‧First comparison output

3‧‧‧second controller

31‧‧‧ the first end

32‧‧‧ the second end

33‧‧‧Second control terminal

4‧‧‧Second Comparator

41‧‧‧ Positive input

42‧‧‧ Negative input

43‧‧‧Second comparison output

5‧‧‧ load

51‧‧‧input connection

52‧‧‧LCD Capacitor

IOVCC‧‧‧First Voltage

VCI‧‧‧Second Voltage

VDDD‧‧‧Drive voltage

V1‧‧‧ first critical voltage

V2‧‧‧Second critical voltage

VG1‧‧‧first control signal

VG2‧‧‧Second control signal

Iload‧‧‧Drive current

I1‧‧‧first current

I2‧‧‧second current

Claims (4)

A power switching circuit is suitable for being electrically connected between a first power source, a second power source, and an input connection terminal of a load to provide a driving voltage to the input connection terminal. The power switching circuit includes: 第一 a first The controller converts a first voltage from the first power source into the driving voltage and outputs the first voltage to the input connection terminal of the load, and allows a first current from the first power source to flow into the input connection terminal through itself. A second controller, comprising a first end electrically connected to the second power source, a second end electrically connected to the input connection end of the load, and a second control end, the second control end receiving a The second control signal of the driving voltage is used to control the conduction between the first terminal and the second terminal. When the first terminal and the second terminal are connected, the first terminal receives a signal from the second terminal. A second voltage of the power source, the second controller converts the second voltage to the driving voltage and outputs the second voltage, and allows a second current from the second power source to flow into the load through the output A connection terminal; and a second comparator including a second comparison output terminal electrically connected to the second control terminal of the second controller, the second comparator according to a magnitude relationship between a second threshold voltage and the driving voltage The second control signal is generated and output at the second comparison output terminal. The power switching circuit according to claim 1, wherein when the second comparator judges that the driving voltage is less than the second threshold voltage, the second control terminal of the second controller controls the first controller according to the second control signal. There is conduction between one end and the second end. The power switching circuit according to claim 2, wherein the first controller includes a first terminal electrically connected to the first power source, a second terminal electrically connected to an input connection terminal of the load, and a first control terminal. The first control terminal receives a first control signal related to the driving voltage to control the conduction or non-conduction between the first terminal and the second terminal of the first controller; the power switching circuit further includes a first A comparator. The first comparator includes a first comparison output terminal electrically connected to a first control terminal of the first controller. The first comparator is based on a first threshold voltage greater than the second threshold voltage and the driving. The magnitude relationship between the voltages generates the first control signal and outputs the first control signal; when the first comparator determines that the driving voltage is greater than the first threshold voltage, the first control terminal of the first controller Controlling non-conduction between the first terminal and the second terminal according to the first control signal. The power switching circuit according to any one of claims 1 to 3, wherein the load is a display panel including a plurality of liquid crystal capacitors, and a driving current is allowed to flow into the input connection terminal to charge the liquid crystal capacitors. And the driving current is the first current or the sum of the first current and the second current.