KR20190066824A - Switching regulator using ESR emulation - Google Patents

Abstract

The present invention relates to a switching regulator using ESR emulation capable of accurately outputting a DC level of output voltage. The switching regulator using ESR emulation comprises: a switching unit repeatedly turned on-off in accordance with an input driving signal to output switching voltage; a first comparator having a first input terminal receiving standard voltage, and a second input terminal receiving feedback voltage of the switching unit, connected with the input terminal of the switching unit, and outputting a comparison value of the voltage inputted to each of the first input terminal and the second input terminal to the switching unit; and an emulation unit connected to the second input terminal and adding a ripple signal filtering the switching voltage to the feedback voltage.

Description

[0001] The present invention relates to a switching regulator using ESR emulation,

The present invention relates to a switching regulator using ESR emulation.

A regulator is a device that converts an input voltage into an output voltage of a certain size and outputs it. It is generally used in a DC / DC converter, and is divided into a linear regulator and a switching regulator. A switching regulator is a regulator that adjusts the voltage precisely by adjusting the amount of pulses flowing to the output stage, and controls the switching regulator in various ways.

One of the methods for controlling the switching regulator is a voltage mode, and Fig. 1 shows a switching regulator circuit in a voltage mode.

The switching regulator of the voltage mode shown in FIG. 1 is designed as a single feedback loop, which facilitates circuit analysis and reduces noise. However, since it is necessary to detect a change in load with a change in output, There is a disadvantage that the response is slow because the error amp is used.

In order to overcome the drawbacks of the switching regulator of the voltage mode as shown in FIG. 1, a hysteretic switching regulator is used, and FIG. 2 shows a hysteretic switching regulator circuit. In the case of a hysteretic switching regulator, a switching operation is controlled by using a ripple generated by a capacitor at an output stage. However, there is a problem that the frequency varies depending on the load, and a COT On time) or AOT (Adaptive Constant On Time) method, but the COT method has a problem that the frequency changes.

On the other hand, recently, due to the development of the technology, the ESR resistance of the capacitor used in the output stage is reduced, and the ripple of a sufficient size is not produced at the output stage, and it is difficult to control the switching regulator in the hysteretic mode using ripple at the output stage.

Korean Registered Patent No. 10-1798113 ("Pseudo-Current Mode Hysteresis Control Method, Pseudo Inductor Current Emulator and Hysteretic Switching DC-DC Converter of Switched DC-DC Converter, "

It is an object of the present invention to provide a switching regulator using ESR emulation according to the present invention. In the control of a switching regulator in a hysteretic mode, an artificial ripple is generated in an output voltage of a regulator The present invention provides a switching regulator using ESR emulation that can more easily control a switching regulator in a hysteretic mode and accurately output a DC level of an output voltage by performing ESR emulation.

According to an aspect of the present invention, there is provided a switching regulator using ESR emulation. The switching regulator includes a switching unit for outputting a switching voltage by repeatedly switching on and off according to an input driving signal, A feedback voltage of the switching unit is input to a second input terminal, an output terminal is connected to an input terminal of the switching unit, and a comparison value of a voltage input to each of the first input terminal and the second input terminal is output to the switching unit. 1 comparator, and an emulation unit connected to the second input terminal, for adding a ripple signal obtained by filtering the switching voltage to the feedback voltage.

The emulation section may further include a low pass filter for receiving the switching voltage and performing low pass filtering, a sample and hold section for sampling the valley value of the output voltage of the low pass filter, and a sample and hold section for sampling the output difference between the low pass filter and the sample and hold section And outputting the result to the second input terminal of the first comparator.

The emulation unit may further include a single pulse generator for generating a single pulse signal when an ON signal for turning on the switching unit is inputted.

The sample and hold unit includes a switch for receiving a pulse signal of the single pulse generating unit and connecting both ends thereof, and a storage unit connected to one end of the switch for storing a voltage inputted thereto.

The low-pass filter receives the switching voltage divided by voltage.

Further, the switching regulator using ESR emulation according to the present invention may further include an on-time generator for outputting a reset signal to adjust the on-time of the switching unit according to the switching voltage.

Further, the switching regulator using ESR emulation according to the present invention further includes a minimum off-time generator for outputting an OFF signal so that the switching unit is turned off after a minimum OFF period.

The SR flip-flop further includes an SR flip-flop receiving the output value of the first comparator as the set input value after the minimum OFF period, receiving the output value of the ON-time generator as the reset input value, and outputting the driving signal to the switching unit .

The switching unit may include a switch and a gate driver for applying a driving signal to the switch, and the gate driver may include a non-overlap circuit.

According to the switching regulator using the ESR emulation according to the present invention as described above, an artificial ripple signal is generated in the emulation unit according to the switching voltage of the present invention, and the generated ripple signal is loaded on the feedback voltage and compared with the reference voltage. There is an effect that the switching regulator can be stably operated even if ripple of a sufficient size is not generated because the ESR resistance of the capacitor used is small.

Also, since the emulation section samples the valley value of the low-pass filtered output voltage through the sample and hold section and outputs the OTA current using the sampled valley value, the DC level of the voltage input to the second input terminal of the first comparator So that it is possible to output an accurate DC level.

In addition, the present invention has an effect that the on-time generating unit can adjust the on-time in accordance with the increase or decrease of the output load and cope with the change of the load immediately.

1 is a circuit diagram of a switching regulator of a conventional voltage mode.
2 is a circuit diagram of a conventional hysteretic mode switching regulator.
3 is a circuit diagram of a switching regulator according to an embodiment of the present invention.
4 is a circuit diagram of an on-time generating unit according to the present invention;
5 is a circuit diagram of an off-time generator of the present invention;
6 is a circuit diagram of the emulation section of the present invention;
7 is a voltage graph of the emulation section of the present invention.

Hereinafter, a preferred embodiment of a switching regulator using ESR emulation according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a circuit diagram of a switching regulator using ESR emulation according to an embodiment of the present invention. FIGS. 4 and 5 are circuit diagrams of a switching regulator using ESR emulation according to an embodiment of the present invention, In the circuit shown in Fig.

3 to 5, a switching regulator using ESR emulation according to an embodiment of the present invention includes a switching unit 100, a first comparator 200, an on-time generating unit 300, a minimum off- Unit 400, and an emulation unit 500. [0040]

As shown in FIG. 1, the switching unit 100 repeatedly turns on and off according to an input driving signal to output a switching voltage. The switching voltage output from the switching unit 100 may theoretically be a spherical file, but a different form may be output depending on the environment.

로 출력되며, 직렬로 연결된 저항을 이용해

보다 분배된(감소된) 피드백 전압

이 후술할 구성에 사용될 수 있다.The switching voltage is filtered through a filter section (not shown) consisting of an inductor and a capacitor,

, And using a resistor in series

More distributed (reduced) feedback voltage

Can be used in a configuration described later.

As shown in FIG. 1, the switching unit 100 may include a switch 110 and a gate driver 120 for the operation as described above.

At least one semiconductor switch may be used as the switch 110, and the gate driver 120 may be repeatedly turned on and off by a drive signal to output a switching voltage.

으로 출력된다. V_{LX와

는 각각 부하단의 크기에 영향을 받으며, V_{LX는 비교적

보다 부하단의 크기에 영향을 덜 받는다.V_ {LX of the switch 110 is connected to an output voltage of an embodiment of the present invention through a filter portion composed of an inductor and a capacitor

. V_ {LX and

Are influenced by the size of the lower end, and V_ {LX is relatively

And is less affected by the size of the bottom edge.

The gate driver 120 outputs a driving signal to the switch 110 according to an input, and may include a non-overlap circuit 121. [ The gate driver 120 prevents the high side and the low side of the switch 110 from turning on at the same time through the non overlap circuit 121 to prevent the flow of the shot- have.

이 입력되고, 제2입력단자(220)로는 피드백 전압

이 입력된다.The first comparator 200 includes a first input terminal 210, a second input terminal 220, and an output terminal (not shown). The first comparator 200 compares the magnitudes of voltages input to the first and second input terminals And outputs the comparison voltage to the output terminal. Specifically, when the voltage input to the first input terminal 210 (+) is greater than the voltage input to the second input terminal 220 (-), the first comparator 200 outputs a voltage having a predetermined value And may not output a voltage when the voltage input to the second input terminal 220 is greater than or equal to the voltage input to the first input terminal 210. As shown in Figure 3, 210) is a constant reference voltage

And the second input terminal 220 is supplied with a feedback voltage

.

을 입력으로 받으며, 제2비교기(310)를 포함할 수 있다.The on-time generating unit 300 outputs a reset signal to adjust the on-time of the switching unit 100 according to the switching voltage. 4 shows a circuit diagram of the on-time generating unit 300. As shown in FIG. 4, the on-time generating unit 300 generates the on-

And may include a second comparator 310.

이 일정 전압이 될 경우, 도 4에 도시된 온 타임 생성부(300)의 커패시터를 충전하도록 직류전류가 흐른다. 직류전류에 의해 커패시터가 충전됨에 따라 제2비교기(310)의 제1입력단자(311)의 입력전압(+)은 시간이 지날수록 점점 증가하며, 제2비교기(310)는 제1입력단자(311)의 입력전압이 제2입력단자(312)에 입력되는 입력전압(-)보다 높아질 경우, 리셋신호를 출력한다. 제2입력단자(312)에는 스위칭 전압

을 두 번 로우 패스 필터링한 전압이 입력될 수 있다. 이는 로우 패스 필터링을 통해 스위칭 전압

을 출력전압

으로 에뮬레이션한 전압을 제2비교기에서 사용하기 위해서이다. 단, 도 4와 같이 스위칭 전압

을 두 번 로우 패스 필터링하는 것은 본 발명의 일실시예로써, 본 발명은 이에 한정하지 않고 스위칭 전압이 적어도 한 번 이상 로우 패스필터링 되어 제2입력단자(312)에 입력될 수 있으며, 이 외에도

이 직접 제2입력단자(312)에 입력될 수 있다.Specifically, when the switching unit 100 is turned on,

In the case of a constant voltage, a direct current flows to charge the capacitor of the on-time generator 300 shown in FIG. The input voltage (+) of the first input terminal 311 of the second comparator 310 gradually increases with time as the capacitor is charged by the DC current, and the second comparator 310 increases the voltage 311 is higher than the input voltage (-) input to the second input terminal 312, the reset signal is output. The second input terminal 312 is supplied with a switching voltage

A low-pass filtered voltage can be input. This allows the switching voltage

Output voltage

In order to use the emulated voltage in the second comparator. However, as shown in FIG. 4,

The low-pass filtering is performed by the low-pass filtering of the switching voltage at least once, so that the switching voltage can be input to the second input terminal 312. In addition,

Can be directly input to the second input terminal 312. [

의 크기에 따라 증가하는 속도가 달라진다. 예를 들어 스위칭 전압

는 부하단의 영향을 받으므로 부하단이 클 경우 감소할 수 있다.

가 감소될 경우 도 4의 커패시터를 충전하는 전류 또한 작아져 커패시터가 충전되는 시간 또한 늘어날 수 있으며, 이에 따라 리셋신호가 출력되는 시간간격이 늘어날 수 있는데, 이는 스위치부(100)의 온 타임을 증가시키게 되므로, 부하단의 크기에 따라 온 타임을 조절하는 것이 가능하다. 즉, 본 발명의 일실시예는 부하단의 크기에 따라 온 타임 생성부(300)에서 즉각적으로 스위칭부(100)의 온 타임을 보상함으로써, 부하단의 변동에 따른 주파수 변동을 감소시킬 수 있다.The DC current to charge the capacitor of FIG. 4 corresponds to the switching voltage

The rate of increase depends on the size. For example,

Is influenced by the lower end, it can be reduced when the lower end is large.

The current to charge the capacitor of FIG. 4 is also reduced, and the time for charging the capacitor can also be increased. As a result, the time interval during which the reset signal is output can be increased. This increases the ON time of the switch unit 100 It is possible to adjust the on-time according to the size of the lower end. That is, according to one embodiment of the present invention, the on-time of the switching unit 100 is immediately compensated by the on-time generating unit 300 according to the size of the lower stage, .

The interval at which the reset signal output from the on-time generator 300 is generated can be adjusted by changing the values of the resistors and capacitors shown in FIG. 4 during design.

3, in an embodiment of the present invention, the first comparator 200 and the on-time generator 300 output the driving signals to the switching unit 100 according to the values output from the first comparator 200 and the on- , And an SR flip-flop (600).

The SR flip-flop 600 receives the output value of the first comparator 200 as a set value and receives the output value of the on-time generator 300 as a reset value to determine the output value Q. The output values according to the input values of the SR flip-flop 600 are shown in Table 1 below.

[Table 1]

As shown in Table 1, the setting value output from the first comparator 200 is input to the SR flip-flop 600, and when the reset value is not input in the ON-time generator 300 The SR flip-flop 600 outputs a driving signal (1 is outputted). However, even if the first comparator 200 does not input the setting value, the SR flip-flop 600 changes And outputs the driving signal without the driving signal. Then, when the reset value is input to the SR flip-flop 600 in the on-time generating unit 300, the SR flip-flop 600 does not output the driving signal, thereby turning off the switching unit 100.

FIG. 5 shows a circuit of the minimum off-time generator 400. FIG. The minimum off-time generating unit 400 outputs an OFF signal so that the switching unit 100 is turned off after the minimum OFF period. That is, the minimum off-time generator 400 guarantees the minimum off-time of the switching unit 100.

을 사용하는 것이 아닌, 고정된 전압을 사용한다는 점이다. 즉, 최소 오프 타임 생성부(400)에서는 고정된 간격으로 오프신호인

을 출력한다. 최소 오프 타임 생성부(400)에서 출력되는

는 제1비교기(200)의 출력값이 입력되는 AND게이트로 입력된다. AND게이트는 입력되는 값이 모두 1일 경우 1을 출력하므로,

가 출력되기 전까지 스위칭부(100)를 턴 온 시키는 온 신호가 일력되지 않는다.The minimum off-time generating unit 400 includes a third comparator 410 similar to the on-time generating unit 300, except that the on-time generating unit 300 differs from the on-

, But rather uses a fixed voltage. That is, in the minimum off-time generating unit 400,

. The minimum off-time generating unit 400 outputs

Is input to the AND gate to which the output value of the first comparator 200 is inputted. The AND gate outputs 1 when the input value is all 1,

The ON signal for turning on the switching unit 100 is not turned on until the ON signal is output.

FIG. 6 is an enlarged circuit of the emulation unit 500, which is a part of FIG. 6, the emulation unit 500 may include a single pulse generator 510, a low-pass filter 520, a sample and hold unit 530, and an OTA 540.

The single pulse generating unit 510 generates a single pulse signal when the ON signal is input to the switching unit 100. [

을 입력받아,

을 로우 패스 필터링한다. 도 6에 도시된 바와 같이, 저역 통과 필터(520)는 온 타임 생성부(300)와 유사하게

을 직접 입력받는 것이 아닌, 직렬로 연결된 저항을 통해 분배된 전압을 입력받음으로써 저역 통과 필터(520)의 필터 계수를 감소시킬 수 있어, 동작 속도를 향상시킬 수 있다.The low-pass filter 520 has a switching voltage

Lt; / RTI >

Pass filtering. As shown in FIG. 6, the low-pass filter 520 is similar to the on-time generator 300

It is possible to reduce the filter coefficient of the low-pass filter 520 by receiving the divided voltage through the resistor connected in series, thereby improving the operation speed.

The sample and hold unit 530 may include a switch 531 and a capacitor 532 as shown in FIG. 6 for sampling and holding (holding) a particular output value.

는 일정한 값을 유지하게 된다.The switch 531 operates when a pulse generated by the single pulse generator 510 is inputted in the state shown in FIG. 6, and connects the both ends of the switch 531. When the switch 531 is connected, the capacitor 532 is charged for a while, and when the switch 531 returns to the state shown in Fig. 6, the capacitor 532 is charged

Is maintained at a constant value.

Although not shown in FIG. 6, a resistor is connected in series between the switch 531 and the capacitor 532, so that the voltage input through the switch 531 can be low-pass filtered once more to stabilize the voltage.

The capacitor 532 is an example of a storage unit for storing a voltage value input by using the switch 531. The capacitor 532 can sample and hold a voltage value inputted using the switch 531 through another method or element other than the capacitor.

가 입력되고, 제2입력단자(542)에는 샘플 앤 홀드부(530)에서 홀드된 전압인

이 입력되며, OTA(540)는

와

의 전압의 차를 OTA전류로 출력하여 제1비교기(200)의 제2입력단자(220)로 입력한다. 단, 본 발명은 저역 통과 필터(520)와 샘플 앤 홀드(530)의 출력차를 제1비교기(200)의 제2입력단자(220)에 출력하는 수단의 일예로써 OTA(540)를 제시한 것일 뿐, 이에 한정하는 것은 아니며, 다양한 방식으로 저역 통과 필터(520)와 샘플 앤 홀드(530)의 출력차를 출력하는 수단이 사용될 수 있다.An OTA (Operational Transconductance Amplifier) 540 outputs the difference in voltage input to the input terminal as an OTA current. The output terminal of the low pass filter 520 is connected to the first input terminal 541 of the OTA 540,

And the second input terminal 542 receives the voltage held in the sample and hold unit 530

And the OTA 540 receives

Wow

And outputs the difference to the second input terminal 220 of the first comparator 200. The OTA 540 is an example of a means for outputting the output difference between the low-pass filter 520 and the sample-and-hold 530 to the second input terminal 220 of the first comparator 200 A means for outputting the output difference of the low-pass filter 520 and the sample-and-hold 530 in various manners may be used.

7B shows the output voltage of the low pass filter 520, FIG. 7C shows the output voltage of the sample and hold 530, FIG. 7D shows the output voltage of the OTA 540, Respectively.

가 값을 가질 때이며, 이는 도 7a에 도시된 저역 통과 필터(520)에 구형파가 입력될 때와 동일하다. 즉, 샘플 앤 홀드부(530)는 삼각파 형태로 나타나는 저역 통과 필터(520)의 밸리값을 샘플링 및 홀드한다.7A and 7B, the rectangular wave input to the low-pass filter 520 is converted into a triangular wave while being low-pass filtered, and the triangular wave, which is an output value of the low-pass filter 520, is used as a ripple. The sample and hold unit 530 connects both ends of the switch 531 when the pulse signal is inputted from the single pulse generating unit 510 and samples and holds the output value of the low pass filter 520. Since the time for inputting the pulse signal by the single pulse generator 510 is when the switch 110 is turned on by inputting the driving signal to the switching unit 100 in the SR flip-flop 600,

Is the same as when a square wave is input to the low-pass filter 520 shown in Fig. 7A. That is, the sample and hold unit 530 samples and holds the valley value of the low-pass filter 520 appearing in the form of a triangle wave.

Since the OTA 540 outputs the difference between the output of the low-pass filter 520 and the output of the sample-and-hold unit 530 as the full OTA current, the OTA current shown in FIG. 7D is obtained by multiplying the triangular wave shown in FIG. The shifted form appears.

7D is input to the second input terminal 220 through a separate resistor (not shown), and the first comparator 200 compares the reference voltage with the feedback voltage (to which the output value of the OTA is added) And outputs a comparison voltage. That is, even if the ESR resistance of the capacitor used at the output terminal of the regulator is small, the regulator can be operated stably by adding an artificial ripple to the feedback voltage.

또한 달라질 수 있으며, 이를 방지하기 위해 샘플 앤 홀드부(530)를 사용한다.It may be possible to use a primary low-pass filtered voltage and a secondary low-pass filtered voltage using a separate additional low-pass filter without using the sample and hold unit 530 shown in FIG. 6 have. However, in this case, the average DC level rises due to the secondarily low-pass filtered voltage being higher than the voltage sampled and held in the sample-and-hold unit, so that the first comparator 200 changes the comparison value according to the ripple size Output voltage

And the sample and hold unit 530 is used to prevent this.

As shown in FIG. 3, an embodiment of the present invention may further include a zero crossing circuit 700. The zero crossing circuit 700 senses the output voltage of the switching unit 100 and controls the switch 110 so that a reverse current does not flow when the output voltage falls below 0. When the DCM is in Discontinuous Conduction Mode, Pulse Skipping Mode) to increase efficiency.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: switching unit 110: switch
120: Gate driver 121: Non-overlap circuit
200: first comparator
210: first input terminal 220: second input terminal
300: On-time generating unit
310: second comparator
311: first input terminal 312: second input terminal
400: minimum off-time generating unit
410: third comparator
500: Emulation unit
510: Single pulse generator 520: Low-pass filter
530: sample and hold unit 531: switch
532: Capacitor 540: OTA
600: SR flip flop
700: zero crossing circuit

Claims (9)

A switching unit for outputting a switching voltage by repeating ON / OFF according to an input driving signal;
And a second input terminal connected to the input terminal of the switching unit for receiving a feedback voltage of the switching unit and having an output terminal connected to the input terminal of the switching unit, A first comparator for outputting a comparison value to the switching unit;
An emulation unit coupled to the second input terminal for adding a ripple signal filtered to the switching voltage to the feedback voltage;
And an ESR emulation circuit coupled to the switching regulator.
The apparatus of claim 1, wherein the emulation unit
A low pass filter for receiving the switching voltage and performing low pass filtering,
A sample and hold section for sampling the valley value of the output voltage of the low-pass filter, and
And means for outputting an output difference between the low-pass filter and the sample-and-hold unit to a second input terminal of the first comparator.
3. The apparatus of claim 2, wherein the emulation unit
Further comprising a single pulse generator for generating a single pulse signal when an ON signal for turning on the switching unit is inputted to the switching regulator.
4. The apparatus of claim 3, wherein the sample and hold section
A switch for receiving the pulse signal of the single pulse generator and connecting both ends thereof;
And a storage unit connected to one end of the switch and storing a voltage input thereto.
3. The receiver of claim 2, wherein the low pass filter
And the switching voltage is divided and input to the switching regulator. The switching regulator using ESR emulation.
The method according to claim 1,
And an on-time generator for outputting a reset signal to adjust the on-time of the switching unit according to the switching voltage.
The method according to claim 1,
Further comprising a minimum OFF time generator for outputting an OFF signal such that the switching unit is turned off after a minimum OFF period.
8. The method of claim 7,
And an SR flip-flop receiving the output value of the first comparator as a set input value after the minimum off period, receiving the output value of the on-time generating unit as a reset input value, and outputting a driving signal to the switching unit. Switching regulator using ESR emulation.
2. The apparatus of claim 1, wherein the switching unit
Switches and
And a gate driver for applying a driving signal to the switch,
Wherein the gate driver includes a non-overlap circuit.

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