Apparatus for regulating output voltage and apparatus for boosting voltage

There is provided an apparatus for regulating an output voltage, including: a sensing circuit sensing an output voltage from a charge pump; a comparator circuit receiving the output voltage from the sensing circuit so as to compare it with a predetermined reference voltage; and a limiter circuit regulating the output voltage according to an output signal from the comparator circuit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2013-0152756 filed on Dec. 10, 2013, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to an apparatus for regulating an output voltage and an apparatus for boosting a voltage.

A touchscreen pad is a device enabling a user to input data by simply touching a screen with her/his finger or another object. To date, such a touchscreen pad has been typically used in industrial or manufacturing facilities. As such touchscreen pads have evolved to have greater responsiveness and multi-touch capabilities, these devices have come into common use in relatively small devices such as mobile phones and display devices.

Further, as touchscreen pad technology is rapidly advancing, electronic devices such as laptop computers, mobile phones and smartphones are increasingly being provided with touch panels, in place of traditional data input devices such as keyboards and computer mice. Touch panels may be divided into capacitive touch panels and resistive touch panels, and recently, the former have been more commonly employed.

Capacitive touch panel determine the position of a touch by detecting changes in capacitance occurring in capacitors when touched by a finger. Unfortunately, capacitive touch panels have a drawback in that a signal to noise ratio (SNR) may be reduced due to external noise (power noise, LCD noise and the like) as the size of a touch panel is increased, and thus a touch may not be readily recognized. To overcome this, a method of boosting a voltage by using a charge pump so that the panels are robust against noise is commonly used. A charge pump has characteristics in which an output voltage therefrom varies according to a load current, and the output voltage from the charge pump may be increased due to external factors or the like.

Patent Document 1 below discloses a charge pump circuit able to obtain a desired output voltage without exceeding withstanding voltages of integrated circuits or the like by controlling levels of charges accumulated in a charge accumulation capacitor. However, Patent Document 1 fails to disclose the feature of regulating the output voltage from a charge pump by way of reducing the output voltage if it is sensed that the output voltage from the charge pump becomes higher, as will be discussed in the present disclosure.

RELATED ART DOCUMENT

SUMMARY

An aspect of the present disclosure may provide an apparatus for regulating an output voltage from a charge pump that reduces the output voltage if it is sensed that the level of the output voltage is increased due to load current or external factors, and an apparatus for boosting a voltage.

According to an aspect of the present disclosure, an apparatus for regulating an output voltage may include: a sensing circuit sensing an output voltage from a charge pump; a comparator circuit receiving the output voltage from the sensing circuit so as to compare it with a predetermined reference voltage; and a limiter circuit regulating the output voltage according to an output signal from the comparator circuit.

The sensing circuit may include at least one resistor for sensing the output voltage from the charge pump.

The comparator circuit may include at least one comparator comparing the output voltage with the predetermined reference voltage so as to output the output signal to the limiter circuit according to the comparison result.

The limiter circuit may include: first and second diode circuits including a plurality of diodes connected in series; and a switching circuit having one terminal connected to a first node between the first and second diode circuits and having the other terminal grounded.

The switching circuit may perform switching operations according to the output signal to connect or disconnect a signal path between the first node and ground.

According to another aspect of the present disclosure, an apparatus for regulating an output voltage may include: a sensing circuit sensing an output voltage from a charge pump; a first comparator circuit comparing the output voltage with a first reference voltage to generate a first output signal; a second comparator circuit comparing the output voltage with a second reference voltage to generate a second output signal; and a limiter circuit performing switching operations according to the first and second output signals received from the first and second comparator circuits, respectively, to regulate the output voltage.

The limiter circuit may include: first to third diode circuits including a plurality of diodes connected in series; a first switch having one terminal connected to a first node between the first and second diode circuits, and the other terminal grounded; and a second switch having one terminal connected to a second node between the second and third diode circuits, and the other terminal grounded.

The limiter circuit may switch the first switch on and off according to the first output signal received from the first comparator circuit so as to connect or disconnect a signal path between the first node and ground, and the limiter circuit switches the second switch on and off according to the second output signal received from the second comparator circuit so as to connect or disconnect a signal path between the second node and ground.

The first and second switches may be field effect transistors (FETs) or bipolar junction transistors (BJTs).

According to another aspect of the present disclosure, an apparatus for boosting a voltage may include: a charge pump boosting an input voltage by performing switching operations to output a first output voltage; an output voltage regulating unit detecting the first output voltage from the charge pump, comparing the detected first output voltage with a predetermined reference voltage, and adjusting a level of the detected first output voltage based on the comparison result so as to generate a second output voltage; an oscillator adjusting a switching frequency of the charge pump; a regulator supplying the charge pump with driving power; and an inverter controlling operations of the charge pump using the driving power received from the regulator.

The output voltage regulating unit may include a sensing circuit sensing a first output voltage from a charge pump; a comparator circuit comparing the first output voltage from the sensing circuit with a predetermined reference voltage to generate an output signal; and a limiter circuit performing switching operations according to the output signal and regulating the first output voltage according to the switching operations to generate a second output voltage.

The limiter circuit may include: first and second diode circuits including a plurality of diodes connected in series; and a switching circuit having one terminal connected to a first node between the first and second diode circuits and having the other terminal grounded, the switching circuit performing switching operations according to the output signal to connect or disconnect a signal path between the first node and ground.

The switching circuit may perform switching operations according to the output signal to connect or disconnect a signal path between the first node and ground.

The apparatus for boosting a voltage may further include: a driving circuit connected to the output voltage regulating unit and outputting the second output voltage received from the output voltage regulating unit to the output terminal.

DETAILED DESCRIPTION

FIG. 1is a block diagram illustrating an apparatus for regulating an output voltage according to an exemplary embodiment of the present disclosure.

FIG. 2is a block diagram illustrating the apparatus for regulating an output voltage ofFIG. 1in more detail.

Referring toFIGS. 1 and 2, the apparatus for regulating an output voltage according to the exemplary embodiment may include a sensing circuit100, a comparator circuit200, and a limiter circuit300.

The sensing circuit100may sense an output voltage from a charge pump10. That is, the sensing circuit100may be connected to the output terminal of the charge pump10and may include at least one resistor100. Although the sensing circuit100performs voltage sensing by dividing resistors in the exemplary embodiment, the resistor may be replaced by a MOS in a CMOS process, such that the area of the apparatus for regulating an output voltage may be reduced.

The comparator circuit200may compare the output voltage from the charge pump10via the sensing circuit100with a predetermined reference voltage Vref. The comparator circuit200may be connected to the sensing circuit100and may include at least one comparator200. In addition, the reference voltage Vref may be previously determined to be input to the comparator circuit200. Since the output voltage from the charge pump10may be increased by external factors, the reference voltage Vref may be determined by dropping the level of the output voltage using a resistor ladder.

Then, the comparator circuit200may output a signal indicating the comparison result to the limiter circuit300.

The limiter circuit300may receive the signal indicating the comparison result from the comparator circuit200. Further, the limiter circuit300may be connected between the charge pump10and an output terminal Out and may attenuate the output voltage from the charge pump10if it is higher than the reference voltage Vref due to external factors. That is, the limiter circuit300may regulate the output voltage from the charge pump10by decreasing it if it is higher than a desired voltage (reference voltage Vref).

FIG. 3is a circuit diagram of an example of the limiter circuit300shown inFIG. 1.

Referring toFIG. 3, the limiter circuit300may include first and second diode circuit units310and320that have a plurality of diodes connected in series, and a switching circuit330.

That is, the output signal from the comparator circuit200may be transmitted to the limiter circuit300so that the switching circuit330may perform switching operations. The number of stages of the plurality of diodes included in the first and second diode circuit310and320in the limiter circuit300may be determined based on a desired value of the output voltage from the charge pump10.

FIG. 4is a circuit diagram of the apparatus for regulating an output voltage ofFIG. 1in more detail.

Referring toFIG. 4, the operation of the apparatus for regulating an output voltage according to the exemplary embodiment will be described in detail. Initially, the sensing circuit100may sense an output voltage from the charge pump10. The sensing circuit100may output the sensed output voltage to the comparator circuit200.

The comparator circuit200may receive the output voltage from the charge pump10and a predetermined reference voltage Vref to compare them with each other. Then, the comparator circuit200may create a signal indicating the comparison result to output it to the switching circuit330.

The switching circuit330has one terminal thereof connected to a node N and the other terminal thereof grounded, such that it may connect or disconnect a signal path between ground and the node N by performing switching operations. In addition, the switching circuit330may be turned on or off according to the signal indicating the comparison result from the comparator circuit200. In an exemplary embodiment, the switch included in the switching circuit330may be field effect transistor (FETs) or bipolar junction transistor (BJTs).

According to an exemplary embodiment of the present disclosure, each of the plurality of diodes included in the first and second diode circuit units310and320may be turned on typically at 0.7 V, and the number of stages of the plurality of diodes may be determined according to a desired output voltage from the charge pump10.

FIG. 5is a block diagram illustrating an apparatus for regulating an output voltage according to another exemplary embodiment of the present disclosure.

Referring toFIG. 5, in the apparatus for regulating an output voltage according to another exemplary embodiment of the present disclosure, the number of stages of the plurality of diodes included in the limiter circuit300and the number of comparators included in the comparator circuit200may be changed according to a desired output voltage from the charge pump10.

In the example shown inFIG. 5, the comparator circuit200includes first and second comparators210and220, and the limiter circuit300includes first to third diode circuit units310,320and330, each of which has a plurality of diodes.

In addition, the limiter circuit300may further include a first switch330that receives a first output signal indicating the comparison result from the first comparator circuit210to perform switching operations, and a second switch331that receives a second output signal indicating the comparison result from the second comparator circuit220to perform switching operations.

The first switch330may have one terminal thereof connected to a first node N1 and the other terminal thereof grounded, such that it may connect or disconnect a signal path between ground and the first node N1 by performing switching operations.

The second switch331may have one terminal thereof connected to a second node N2 and the other terminal thereof grounded, such that it may connect or disconnect a signal path between ground and the second node N2 by performing switching operations.

In an exemplary embodiment, the first and second switches330and331may be field effect transistors (FETs) or bipolar junction transistors (BJTs).

That is, the apparatus for regulating an output voltage according to the exemplary embodiment may sense an output voltage from the charge pump10with the sensing circuit100, and the sensed output voltage from the charge pump10may be received by the first and second comparators210and220.

Then, the first comparator210may generate the first output signal by comparing the output voltage from the charge pump10via the sensing circuit100with a first predetermined reference voltage Vref1, and the second comparator220may generate the second output signal by comparing the output voltage from the charge pump10via the sensing circuit100with a second predetermined reference voltage Vref2.

The first output signal may be provided to the first switch330and the second output signal may be provided to the second switch331. Accordingly, in order to obtain a desired value of the output voltage from the charge pump10, the apparatus for regulating an output voltage according to the exemplary embodiment may compare the first and second reference voltages Vref1 and Vref2 with the output voltage, and accordingly perform switching operations to change the number of the stages of the plurality of diodes, to thereby attenuating the level of the output voltage.

FIG. 6is a block diagram of an apparatus for boosting a voltage including an apparatus for regulating an output voltage according to an exemplary embodiment of the present disclosure as an output voltage regulating unit.

Referring toFIG. 6, the apparatus for boosting a voltage according to another exemplary embodiment of the present disclosure may include a charge pump10boosting an input voltage by performing switching operations to output a first output voltage; an output voltage regulating unit11sensing the first output voltage from the charge pump10, comparing the sensed first output voltage with the a predetermined reference voltage Vref to adjust the level of the sensed first output voltage based on the comparison result, to output a second output voltage; an oscillator12adjusting a switching frequency of the charge pump10; a regulator13supplying the charge pump10with driving power; and an inverter14controlling the operation of the charge pimp10using the driving power received from the regulator13.

The apparatus for boosting a voltage may further include a driving circuit15connected to the output voltage regulating unit11and outputting the second output voltage received from the output voltage regulating unit11to the output terminal.

The output voltage regulating unit11may include a sensing circuit100, a comparator circuit200, and a limiter circuit300. The comparator circuit200may receive the output voltage from the charge pump10and a predetermined reference voltage Vref for comparison. Then, the comparator circuit200may create a signal indicating the comparison result to be output to the switching circuit330. The switch330has one terminal thereof connected to a node N and the other terminal thereof grounded, such that a signal path between ground and the node N may connected or disconnected by performing switching operations.

In addition, the switch330may be turned on or off according to the signal indicating the comparison result from the comparator circuit200.

As set forth above, according to exemplary embodiments of the present disclosure, the output voltage from a charge pump may be reduced to a level within a predetermined range, if it is sensed that the level of the output voltage is increased due to external factors, such that the output voltage may be stabilized and the SNR characteristic may by improved.