CN106033930A - switching regulator - Google Patents

Abstract

A switching regulator is used for receiving an input voltage and correspondingly providing an output voltage. The switching regulator includes a switching circuit, an inductor, a DC compensation circuit and a control circuit. The switching circuit is coupled to the input voltage; the inductor is coupled to the switching circuit and used for receiving the input voltage from the switching circuit and providing the output voltage to a load; the DC compensation circuit is used for comparing a feedback signal from the output voltage with a threshold value so as to dynamically adjust a DC compensation voltage; the control circuit is used for determining the duty cycle of the switching circuit, wherein the control circuit at least adjusts the duty cycle of the switching circuit according to the DC compensation voltage.

Description

switching regulator

technical field

The present invention relates to a switching voltage regulator, especially a switching voltage regulator that can dynamically adjust the duty cycle according to the working state.

Background technique

Generally speaking, the easiest way to reduce the voltage of a DC power supply is to use a linear regulator, but this method consumes more power. In contrast, switching regulators have been widely used because they consume less power in operation. For example, common switching regulators are boost regulators and buck regulators. These switching regulators use a feedback path to adjust the duty of their switching switches. duty cycle.

However, switching regulators in the prior art often cannot provide good transient response. For example, the switching regulator in the prior art cannot adjust the duty cycle correspondingly according to the load condition of the system. Therefore, there is a need to provide a new switching regulator to solve the above problems.

Contents of the invention

An embodiment of the present invention provides a switching voltage regulator, the switching voltage regulator is used to receive an input voltage and correspondingly provide an output voltage, and includes a switching circuit, an inductor, a DC compensation circuit and A control circuit. The switching circuit is coupled to the input voltage; the inductor is coupled to the switching circuit for receiving the input voltage from the switching circuit and providing the output voltage to a load; the DC compensation circuit is used for receiving the input voltage from the switching circuit A feedback signal of the voltage is compared with a threshold to dynamically adjust a DC compensation voltage; the control circuit is used to determine the duty cycle of the switching circuit, wherein the control circuit adjusts the duty of the switching circuit at least according to the DC compensation voltage cycle.

The switching regulator of the embodiment of the present invention can dynamically adjust a DC compensation voltage according to the feedback signal from the output voltage, so as to adjust the duty cycle of the switching circuit accordingly, wherein when the load terminal is from light load to heavy load Accelerate the step-up duty cycle and speed up the step-down duty cycle when the load changes from heavy load to light load, so that the load end has a better transient response (transient response) and improves the overall voltage regulation performance.

Description of drawings

FIG. 1 is a schematic diagram of a switching regulator according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a switching regulator according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of the sum signal of the comparator shown in FIG. 2 .

FIG. 4 shows the waveforms generated by the sum signal of the comparator shown in FIG. 2 in different operation modes.

FIG. 5 is a schematic diagram of summed signals and corresponding output signals of the comparator shown in FIG. 2 under different load conditions.

Symbol Description

100, 200 Switching Regulators

20 switching circuit

30 inductor

40 DC compensation circuit

50 control circuit

52 Error amplifier

54 Comparators

56 Control logic circuit

60 voltage divider circuit

V _in input voltage

V _O output voltage

C _O Capacitance

Q1 first switch

Q2 second switch

R _O load

C _O Capacitance

R _L , R _i resistance components

R _C resistor assembly

R1, R2 resistors

V _FB feedback signal

V _C control signal

V _REF reference voltage

V _DC DC compensation voltage

V _CS sense voltage

V _S slope compensation signal

_VTH Threshold

W1, W2, W3 waveforms

detailed description

Certain terms are used throughout the specification and appended claims to refer to particular components. Those of ordinary skill in the art should understand that hardware manufacturers may use different terms to refer to the same component. The description and the scope of the appended claims do not use the difference in name as the way to distinguish components, but the difference in function of the components as the criterion for distinguishing. "Includes" mentioned throughout the specification and appended claims is an open term, so it should be interpreted as "including but not limited to". In addition, the term "coupled" herein includes any direct and indirect means of electrical connection. Therefore, if it is described that a first device is coupled to a second device, it means that the first device may be directly electrically connected to the second device, or indirectly electrically connected to the second device through other devices or connection means.

FIG. 1 is a schematic diagram of a switching regulator according to a first embodiment of the present invention. The switching regulator 100 is used for receiving an input voltage V _in and correspondingly providing an output voltage Vo, and includes a switching circuit 20 , an inductor 30 , a DC compensation circuit 40 and a control circuit 50 . The inductor 30 is coupled to the switch circuit 20 for receiving the input voltage V _in from the switch circuit 20 and providing the output current i _L (ie, the inductor current) to a load R _O . During a first operation, the control circuit 50 will turn on the first switch Q1 in the switching circuit 20 and turn off the second switch Q2 in the switching circuit 20, so as to transmit energy from the input voltage V _in to the capacitor C through the inductor 30 _O. In this state, the input voltage V _in can provide current to the load R _O through the inductor 30 . In addition, during a second operation, the control circuit turns off the first switch Q1 in the switching circuit 20 and turns on the second switch Q2 in the switching circuit 20, so as to transfer the energy in the capacitor C _O to the load R _O , The inductor 30 will continue to provide current to the load R _O by reversing its voltage. A resistance component R _C may be coupled between the capacitor C _O and the ground potential (or low logic potential), and a resistance component R _L may be coupled between the inductor 30 and the load R _O , but the present invention does not limit.

The DC compensation circuit 40 is used for comparing a feedback signal V _FB from the output voltage _VO with a predetermined threshold V _TH to dynamically adjust a DC compensation voltage V _DC . The DC compensation circuit 40 transmits the DC compensation voltage V _DC to the control circuit 50 . The control circuit 50 adjusts the duty cycle of the switching circuit 20 at least according to the DC compensation voltage V _DC . In other words, the magnitude of the DC compensation voltage V _DC will affect the length of the duty cycle of the switching circuit 20 . For example, when the feedback signal V _FB is smaller than the threshold V _TH , the DC compensation circuit 40 can reduce the DC compensation voltage V _DC , thereby enabling the control circuit 50 to extend the duty cycle of the switching circuit 20; and when the feedback signal V _FB is larger than the threshold V _TH , the DC compensation circuit 40 can increase the DC compensation voltage V _DC , thereby enabling the control circuit 50 to shorten the duty cycle of the switching circuit. The above operations will be described in detail in subsequent paragraphs. Please note that in an implementation, the DC compensation voltage V _DC is only one of the control parameters referenced by the control circuit 50 , in other words, the length of the duty cycle of the switching circuit 20 is also affected by other control parameters.

Please refer to FIG. 2. FIG. 2 is a schematic diagram of a switching regulator 200 according to a second embodiment of the present invention, wherein the switching regulator 200 can be used as a step-down converter (buck converter), but not as a limit. Please note that the switching regulator 200 can be regarded as one of the specific implementations of the switching regulator 100. Further, the control circuit 50 shown in FIG. However, the switching regulator 100 is not limited to the configuration of the switching regulator 200 . In addition, for the sake of brevity, the similarities between the switching regulator 200 and the switching regulator 100 will not be repeated. As shown in FIG. 2, the switching regulator 200 further includes a voltage divider circuit 60 for generating a feedback voltage V _FB according to the output voltage V _O , wherein the voltage divider circuit 60 can be realized by using the two resistors R1 and R2 shown in the figure. , but the present invention is not limited thereto. In addition, the control circuit 250 includes an error amplifier 52 , a comparator 54 and a control logic circuit 56 . The error amplifier 52 is used for receiving the feedback signal V _FB and comparing the feedback signal V _FB with a reference voltage V _REF to generate a control signal V _C . The comparator 54 can be, for example, a pulse-width modulation (PWM) comparator for receiving the control signal V _C , the DC compensation voltage V _DC transmitted from the DC compensation circuit 40 , and the output terminal corresponding to the switching circuit 20 . A sense voltage V _CS and a slope compensation signal V _S , and generate a comparison result according to the control signal V _C , the DC compensation voltage V _DC , the sense voltage V _CS and the slope compensation signal V _S , wherein the comparison result can be square wave, and the comparator 54 can sum the DC compensation voltage V _DC , the sensing voltage V _CS and the slope compensation signal V _S , and combine the summed input signal (hereinafter referred to as the summed signal) with the control signal V _C Compare to output the square wave. The control logic circuit 56 determines the duty cycle of each switch (ie, the transistors Q1 and Q2 ) in the switching circuit 20 according to the comparison result (ie, the square wave). In this embodiment, the control terminals of the transistors Q1 and Q2 are coupled to the control logic circuit 56, and the control logic circuit 56 will turn on the first switch Q1 and turn off the first switch Q1 during a first operation according to the comparison result sent by the comparator 54. The second switch Q2, and turning off the first switch Q1 and turning on the second switch Q2 during a second operation, wherein the ratio of the on-time T _ON (Q1) of the first switch Q1 to a pulse modulation period T (that is, ) is the duty period D(Q1) of the first switch Q1, and the ratio of the conduction time T _ON (Q2) of the second switch Q2 to the pulse modulation period T (that is, ) is the duty cycle D(Q2) of the second switch Q2, in addition, D(Q1)+D(Q2)=1, that is, the sum of the duty cycle of the first switch Q1 and the duty cycle of the second switch Q2 is all (100%) duty cycle.

Please refer to FIG. 3. FIG. 3 is a schematic _diagram of the _summed input signal of the comparator ₅₄ shown in FIG. The results are summed and can be viewed as either a ramp or a sawtooth. V _CS is a current sense voltage, and its value can be i _L *R, wherein i _L is the output current of the switching circuit 20, and R is the resistance value of the resistance component R _i . By providing the DC compensation voltage V _DC to the comparator 54 , the problem of serious operating errors of the switching regulator 200 under low supply current and low duty cycle conditions can be resolved.

Please refer to FIG. 4 , which is a waveform of the sum signal of the comparator 54 shown in FIG. 2 generated in different operation modes. As shown in Figure 4, from left to right is the waveform W1 generated by DC voltage compensation under low current operation, the waveform W2 generated by DC voltage compensation under low current and low duty cycle operation, and the waveform W2 generated by DC voltage compensation under low current operation. Waveform W3 produced without DC voltage compensation under current and low duty cycle operation. It can be seen from Figure 4 that when the duty cycle is high, the waveform W1 still has sufficient gain even without DC voltage compensation; and when the duty cycle becomes small, the gain of waveform W3 is too small without DC voltage compensation, which is It will cause the operation error of the subsequent circuit, and the waveform W2 can avoid the operation error of the subsequent circuit because of the DC voltage compensation.

Please refer to FIG. 5. FIG. 5 is a schematic diagram of the summed signal and the corresponding output signal of the comparator 54 shown in FIG. model. Firstly, in the middle normal mode, the sum signal of the comparator 54 is the sum of the DC compensation voltage V _DC , the sensing voltage V _CS and the slope compensation signal V _S , and this sum signal will be compared with another of the comparator 54 The control signal V _C at the input terminal is compared to output a square wave correspondingly (which can be regarded as the duty cycle provided to the control logic circuit 56), wherein when the sum signal exceeds the magnitude of the control signal V _C , the comparator 54 The output square wave will drop from high level to low level.

When it is detected that the load (load R _O as shown in Figure 2) is in a heavy load state, most of the current i _L is due to load loss, resulting in the feedback signal V _FB obtained by dividing the load R _O will be smaller than the threshold V _TH . At this time, the first mode on the left can be adopted, wherein the DC compensation circuit 40 will reduce the value of the DC compensation voltage V _DC (that is, provide a DC compensation voltage V _DC lower than the normal mode), so as to delay the summing signal from reaching the control The timing of the magnitude of the signal V _C (ie, the time delayed at the dotted line to reach the control signal V _C ). In this way, the control logic circuit 56 in the control circuit 50 will extend the duty cycle of the switching circuit 20 to obtain a longer charging time, and quickly respond to the above-mentioned overload state.

When it is detected that the load (load R _O as shown in Figure 2) is in a light load state, only a small part of the current i _L is consumed by the load, so the feedback signal V _FB obtained by dividing the load R _O will be greater than the threshold V _TH . At this time, the second mode on the right can be adopted, wherein the DC compensation circuit 40 will increase the value of the DC compensation voltage V _DC (that is, provide a DC compensation voltage V _DC higher than the normal mode), so that the summed signal reaches the control signal The magnitude of _VC is advanced in time (ie, arrives at the control signal _VC earlier than the time at the dotted line). In this way, the control logic circuit 56 in the control circuit 50 shortens the duty cycle of the switching circuit 20 to reduce the charging time of the input voltage. Please note that the threshold value of the DC compensation circuit 40 can be set according to actual application requirements. Preferably, the set threshold value can reflect the load condition of the load R _O terminal, so that the DC compensation circuit 40 can output an appropriate DC compensation voltage. V _DC is given to the control circuit 50 .

To sum up, the switching regulator of the present invention (such as the switching regulator 100, 200 in the embodiment) can dynamically adjust the DC compensation voltage according to the feedback signal from the output voltage, so as to adjust the switching circuit accordingly duty cycle, in which, when the load end changes from light load to heavy load, the step-up duty cycle is accelerated and when the load end changes from heavy load to light load, the step-down duty cycle is accelerated, so that the load end has a better transient response (transient response) ), and improve the overall voltage regulation performance.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the claims of the present invention shall fall within the scope of the present invention.

Claims (10)

1. a switching type voltage stabilizer, in order to receive an input voltage, and provides an output electricity accordingly Pressure, this switching type voltage stabilizer includes:

One switching circuit, is coupled to this input voltage；

One inducer, is coupled to this switching circuit, in order to receive this input voltage from this switching circuit, and There is provided this output voltage to a load；

One DC offset circuit, in order to compare the feedback signal from this output voltage with a threshold value Relatively, dynamically to adjust a direct current compensation voltage；And

One control circuit, in order to determine the responsibility cycle of this switching circuit, wherein this control circuit can be at least The responsibility cycle of this switching circuit is adjusted according to this direct current compensation voltage.

2. switching type voltage stabilizer as claimed in claim 1, wherein when this feedback signal is less than this threshold value, This DC offset circuit reduces this direct current compensation voltage, and then makes this control circuit extend this switching circuit Responsibility cycle.

3. switching type voltage stabilizer as claimed in claim 1, wherein when this feedback signal is more than this threshold value, This DC offset circuit increases this direct current compensation voltage, and then makes this control circuit shorten this switching circuit Responsibility cycle.

4. switching type voltage stabilizer as claimed in claim 1, it is a step-down controller.

5. switching type voltage stabilizer as claimed in claim 1, additionally comprises a bleeder circuit, in order to according to being somebody's turn to do Output voltage produces this feedback voltage.

6. switching type voltage stabilizer as claimed in claim 1, wherein this control circuit includes:

One error amplifier, in order to receive this feedback signal, and enters this feedback signal with a reference voltage Row compares, to produce a control signal；

One comparator, in order to receive this control signal, this direct current compensation voltage, to should switching circuit One sensing voltage and a slope compensation of outfan, and mend according to this control signal, this direct current Repay voltage, this sensing voltage and this slope compensation and produce a comparative result；And

One control logic circuit, in order to adjust the responsibility cycle of this switching circuit according to this comparative result.

7. switching type voltage stabilizer as claimed in claim 6, wherein this switching circuit comprises:

One first switch, has one first end, is coupled to this input voltage, and one controls end, is coupled to this Control logic circuit, and one second end；And

One second switch, has one first end, is coupled to the second end of this first switch, and one controls end, It is coupled to this control logic circuit；

Wherein this control logic circuit according to this comparative result in one first operate during, open this first Switch and close this second switch, and during one second operates, close this first switch and open Open this second switch.

8. switching type voltage stabilizer as claimed in claim 7, wherein this first switch and this second switch For transistor.

9. switching type voltage stabilizer as claimed in claim 6, additionally comprises a resistor assembly, is coupled to this and cuts Change this outfan of circuit, in order to the output electric current of this switching circuit is converted to this sensing voltage.

10. switching type voltage stabilizer as claimed in claim 6, wherein this comparator is that a pulse width is adjusted Comparator processed.