TWI699640B - Contstant on-time controller and buck regulator device using the same - Google Patents

Abstract

A constant on-time controller has a voltage divider, a current ripple extractor, a one-shot on-timer, a comparator and a flip flop. The voltage divider generates a feedback voltage according to a regulator output voltage. The current ripple extractor senses a current in an energy storage inductor of a buck regulator flowing through flowing through an output capacitor's ESR, and generates an extracted ripple current having no DC component accordingly. The one-shot on-timer outputs a constant-on time control signal according to a buck regulator input voltage and the regulator output voltage. The modulation circuit outputs a modulation signal according to a reference voltage signal, the feedback voltage and the extracted ripple current. The flip flop generates a control signal to the buck regulator according to the modulation signal and the constant-on time control signal. An off-time of the buck regulator is determined according to the modulation signal.

Description

Fixed open-circuit time controller and buck converter device using it

The present invention relates to a buck converter, in particular to a constant on-time controller used in a buck converter device.

The fixed open circuit time controller can be used in a buck converter device. Whenever the regulator output voltage drops below the reference voltage, the fixed open circuit time controller can use the regulator output voltage ripple to initiate an open circuit time. The open circuit time can be terminated by the circuit's response to other conditions (such as the level of the regulator input voltage) (generating an open circuit time pulse). During the open-circuit time pulse, energy is directly supplied from the regulator input voltage to the regulator output voltage via the electronic switching device. Similarly, when the open-circuit time pulse has been terminated, the energy stored in the energy storage inductor will be supplied to the regulator output voltage.

A buck converter device with a fixed open-circuit time controller usually includes a circuit that adjusts the interval of the open-circuit time pulse wave as a function of the regulator input voltage and the regulator output voltage, so when the duty cycle is changed Almost a fixed frequency can still be obtained. The output voltage ripple of the regulator is determined to a large extent by a ripple current flowing through the equivalent series resistance (ESR) of the output capacitor in the energy storage inductor. In some applications, multilayer ceramic capacitors have so small ESR that the energy storage inductors The voltage ripple is also small. This will cause two problems for the fixed open time controller, stability and susceptibility to noise.

One of the objectives of the present invention is to provide a fixed open-circuit time controller for a buck converter device to extend a noise margin of the fixed open-circuit time controller.

Another object of the present invention is to provide a fixed open-circuit time controller for a buck converter device to minimize the susceptibility of the fixed open-circuit time controller to noise, so that the jitter of the signal can be reduced. Significantly reduced.

Another object of the present invention is to provide a buck converter device including a buck converter fixed open-circuit time controller, which is electrically connected to the buck converter, so as to solve the stability and ease of noise. Perceptual question.

In order to achieve at least one of the above objectives, the present invention provides a fixed open-circuit time controller including a voltage divider, a current ripple extractor, a single-shot open-circuit timer, a comparator and a flip-flop. The voltage divider generates a feedback voltage according to the output voltage of a regulator. The current ripple extractor senses the current in the energy storage inductor of the buck converter, which flows through the equivalent series resistance of the output capacitor, and accordingly generates an extracted ripple current without a DC component. The single-shot open-circuit timer outputs a fixed open-circuit time control signal based on the input voltage of the buck converter and the output voltage of the regulator. The modulation circuit outputs the modulation signal according to the reference voltage signal, the feedback voltage and the extracted ripple current. The flip-flop generates a control signal to the buck converter according to the modulation signal and the fixed open time control signal. The off time of the buck converter is determined by the modulation signal.

In order to achieve at least one of the above objectives, the present invention provides a buck converter device including a buck converter and a fixed open-circuit time controller electrically connected to the buck converter.

In an embodiment of the present invention, the flip-flop is a reset-set (RS) flip-flop, and a set terminal of the RS flip-flop is electrically connected to the comparator and the single-shot open-circuit timer To receive the comparison result signal and an inverted signal of the fixed open time control signal, and a reset terminal of the RS flip-flop is electrically connected to the single-shot open timer to receive the fixed open time control signal.

In an embodiment of the present invention, the single-shot open-circuit timer includes a capacitor, a current source and a voltage comparator. The current source is electrically connected to the ground via the capacitor, and is suitable for generating a current proportional to the input voltage of the regulator so as to form a first voltage across the capacitor. The voltage comparator is electrically connected to the connection end of the capacitor and the current source, and is suitable for comparing the output voltage of the regulator with the first voltage to output a fixed open-circuit time control signal.

In an embodiment of the present invention, the fixed open time controller further includes a ramp generator. The ramp generator is electrically connected to the modulation circuit to generate a ramp voltage signal. The modulation circuit outputs a modulation signal according to the feedback voltage, the reference voltage signal, the ramp voltage signal and the extracted ripple current.

In an embodiment of the present invention, the current ripple extractor includes a current sense amplifier, a sample-and-hold circuit, and a subtractor. The current sense amplifier senses the current in the energy storage inductor of the buck converter, which flows through the equivalent series resistance of the output capacitor to obtain the sensed current. The sample and hold circuit is electrically connected to the current sense amplifier, and is suitable for sampling and holding the DC component of the sensed current. The subtractor is electrically connected to the current sensing amplifier and the sample-and-hold circuit, and is suitable for subtracting the held DC component from the sensed current to generate an extraction ripple current.

In an embodiment of the present invention, the modulation circuit includes an amplifier, a capacitor, an adder and a modulator. The amplifier receives the reference voltage signal and the feedback voltage to generate an adjusted reference voltage signal. The two ends of the capacitor are electrically connected to the amplifier and the ground respectively. The adder is electrically connected to the amplifier and is adapted to subtract the adjusted reference voltage signal from the first voltage signal associated with the extracted ripple current to generate the second voltage signal. The modulator is electrically connected to the adder and is suitable for generating a modulating signal according to the second voltage signal and the feedback voltage.

In an embodiment of the present invention, the modulation circuit includes an adder and a modulator. The adder is electrically connected to the amplifier and is adapted to subtract the reference voltage signal from the first voltage signal associated with the extracted ripple current to generate the second voltage signal. The modulator is electrically connected to the adder and is suitable for generating a modulating signal according to the second voltage signal and the feedback voltage.

In an embodiment of the present invention, the voltage divider includes a plurality of resistors electrically connected in series.

In summary, the present invention provides a fixed open-circuit time controller for enhancing the noise tolerance of the buck converter device. In addition, the signal jitter can be improved in some embodiments, so the provided fixed open-circuit time controller can further improve the stability and noise tolerance.

11: fixed open time controller

111: Current ripple extractor

112: Voltage divider

113: Modulation circuit

114: Single open timer

115: RS flip-flop

116: ramp generator

12: Buck converter

121: pre-driver

21: Hysteresis comparator

22: current source

23: Voltage comparator

31: current sense amplifier

32: sample and hold circuit

33: Subtractor

41: Amplifier

42: adder

43: Modulator

C ₁ , C ₂ , C _{T_ON} : capacitance

C _O : output capacitance

FB: Feedback voltage

GND: ground

I _SW : current

L _X : Energy storage inductance

M1, M2: Transistor

R _CO : output resistance

R ₁ , R _FBH , R _FBL : resistance

R _LOAD : output load

V _C : Voltage

V _COT : Voltage signal

V _DD : supply voltage

V _IN : Input voltage

V _REF , V _REF ': reference voltage signal

V _REFX : compare voltage signal

V _OUT : output voltage

V _SW : Voltage

T _ON : open circuit time control signal

Fig. 1 is a circuit diagram of an embodiment of a buck converter device of the present invention; Fig. 2A is a circuit diagram of an embodiment of a single-shot open-circuit timer of the present invention; Fig. 2B is a circuit diagram of another embodiment of a single-shot open-circuit timer of the present invention Figure 3 is a circuit diagram of an embodiment of the current ripple extractor of the present invention; Figure 4A is a circuit diagram of an embodiment of the modulation circuit of the present invention; Figure 4B is a circuit diagram of another embodiment of the modulation circuit of the present invention; FIG. 5 is a signal waveform diagram of an embodiment of the buck converter device of the present invention.

In order to make it easier for the examiner to understand the purpose, efficacy and technical features of the present invention, a detailed description of the embodiments of the present invention is provided together with the accompanying drawings.

An embodiment of the present invention provides a buck converter device, which includes a fixed open time controller and a buck converter electrically connected to the buck converter, wherein a current ripple of the fixed open time controller is The wave extractor is used to sense the equivalent series resistance of a current flowing in the energy storage inductor and flowing through an output capacitor (that is, used to sense a low side current of the buck converter) , To remove the DC current component in a sensed current to generate an extracted ripple current, and generate a ripple voltage signal to a comparator of the fixed open time controller according to the extracted ripple current , In order to extend a noise margin of the fixed open time controller.

Furthermore, in another embodiment of the present invention, a ramp generator is used in the fixed open time controller to provide a ramp voltage signal to the comparator of the fixed open time controller, and thus minimize the fixed The open circuit time controller is susceptibility to noise and greatly reduces signal jitter. In short, the provided fixed open-circuit time controller of the buck converter device can solve the problems of stability and susceptibility to noise.

Referring to FIG. 1, FIG. 1 is a circuit diagram of an embodiment of a buck converter device of the present invention. The buck converter device 1 includes a fixed open circuit time controller 11 and the buck converter 12 is electrically connected to the fixed open circuit time controller 11. The buck converter 12 is controlled by the fixed open-circuit time controller 11 to turn on or off. When the buck converter 12 is turned on, the buck converter 12 transfers the energy of the regulator input voltage V _IN to the regulator output voltage V _OUT through an electronic switching device (composed of transistors M1 and M2). When the buck converter 12 is turned off, the energy stored in the energy storage inductor L _X is supplied to the regulator output voltage V _OUT .

The fixed open-circuit time controller 11 receives the regulator output voltage V _OUT and senses the current I _SW flowing through the equivalent series resistance of an output capacitor (that is, the impedance of the resistance R _CO of the output capacitor C _O ) in the energy storage inductor L _X . The current I _SW is also the low-side current of the buck converter 12. The fixed open time controller 11 generates the feedback voltage FB according to the regulator output voltage V _OUT , and generates an extraction ripple current according to a sensed current. The fixed open-circuit time controller 11 can determine the open-circuit time of the buck converter 12 according to the feedback voltage FB and the extracted ripple current (that is, the period during which the buck converter 12 is closed), and according to the regulator input voltage V _IN and The regulator output voltage V _OUT determines an open-circuit time of the buck converter 12 (that is, the period during which the buck converter 12 is turned on). Because the extracted ripple current does not have the DC component of the current I _SW , the DC component of the current I _SW will not be amplified in the fixed open time controller 11, so that the noise tolerance of the fixed open time controller 11 can be extended. In addition, the fixed open-circuit time controller 11 can accurately control the open-circuit time of the buck converter 12.

Furthermore, in order to consider the signal jitter caused by noise, the fixed open time controller 11 further generates a ramp voltage signal, and determines the step-down conversion based on not only the feedback voltage FB and the extracted ripple current, but also the ramp voltage signal. The disconnection time of the device 12. Because of the consideration of the ramp voltage signal, the susceptibility of the fixed open time controller 11 to noise is reduced, and the signal jitter caused by the noise is reduced.

The description of the buck converter 12 will be detailed as follows. The buck converter 12 includes a pre-driver 121 (or a logic circuit), transistors M1 and M2, an energy storage inductor L _X , an output capacitor C _O and an output resistor R _CO . The output load R _LOAD can be electrically connected to the regulator output voltage V _OUT . The output capacitor C _O is electrically connected to the output resistor R _CO in a series connection, wherein the output resistor R _CO is electrically connected to the ground via the output capacitor C _O.

The regulator output voltage V _{OUT is} electrically connected to the output resistor R _CO and the energy storage inductor L _X. Transistors M1 and M2 (for example, PMOS transistors) form an electronic switching device. The gates of the transistors M1 and M2 are electrically connected to the pre-driver 121, the source of the transistor M1 is electrically connected to the regulator input voltage V _IN , and the drain of the transistor M1 is electrically connected to the energy storage inductor L _X and the electric The source of the transistor M2 and the drain of the transistor M2 are electrically connected to the ground. The drains of the transistors M1 and M2 are also electrically connected to the fixed open time controller 11 so that the fixed open time controller 11 can sense the current I _SW .

The pre-driver 121 is used to receive a control signal from the fixed open time controller 11. The pre-driver 121 outputs a gate control signal to the gates of the transistors M1 and M2 according to the control signal. When the transistor M1 is turned on (at the same time, the transistor M2 is turned off), the buck converter 12 is turned on, so that the energy of the regulator input voltage V _IN is transferred to the regulator output voltage V _OUT (that is, the current I _SW will Increase); and when the transistor M2 is turned on (at the same time, the transistor M1 is turned off), the buck converter 12 is turned off, so that the energy stored in the energy storage inductor L _X is supplied to the regulator output voltage V _OUT (also That is, the current I _SW will decrease).

With continued reference to FIG. 1, the description of the fixed open time controller 11 will be as follows. The fixed open-circuit time controller 11 includes a current ripple extractor 111, a voltage divider 112, a modulation circuit 113, a single-shot open-circuit timer 114, a reset-set (RS) flip-flop 115 and a ramp generator器116. The current ripple extractor 111 is electrically connected to the drain of the transistor M2, and is further electrically connected to the modulation circuit 113. The voltage divider 112 is electrically connected to the regulator output voltage V _OUT and the modulation circuit 113. The ramp generator 116 is electrically connected to the modulation circuit 113. The modulation circuit 113 is electrically connected to the reference voltage signal V _REF and the RS flip-flop 115. The RS flip-flop 115 is electrically connected to the pre-driver 121 and the single-shot open-circuit timer 114.

The current ripple extractor 111 senses the current I _SW flowing through the equivalent series resistance of an output capacitor (that is, the low-side current of the buck converter 12) in the energy storage inductor L _X to generate the sensed current, and moves The DC component of the sensed current is removed to generate the extracted ripple current. Then, the current ripple extractor 111 generates a ripple voltage signal to the modulation circuit 113 according to the extracted ripple current.

The ramp generator 116 is used to generate a ramp voltage signal to the modulation circuit 113, and the ramp voltage signal and the ripple voltage signal are combined to form a voltage signal V _COT . As mentioned above, the ramp voltage signal is used to reduce the signal jitter caused by noise, so if the signal jitter does not affect the result (that is, when the voltage signal V _COT is a ripple voltage signal), the present invention does not require a ramp generator 116 .

The voltage divider 112 includes resistors R _FBH and R _FBL , wherein the resistor R _{FBH is} electrically connected to the regulator output voltage V _OUT , the modulation circuit 113 and the resistor R _FBL , and the resistor R _{FBL is} electrically connected to the ground. The voltage divider 112 generates a feedback voltage FB across the resistor R _FBL according to the regulator output voltage V _OUT , and the feedback voltage FB is received by the modulation circuit 113.

The modulation circuit 113 generates a modulation signal according to the addition result of the voltage signal V _COT and the feedback voltage FB and the reference voltage signal V _REF , and outputs the modulation signal to the set terminal of the RS flip-flop 115. For example, when the addition result of the voltage signal V _COT and the feedback voltage FB is less than the reference voltage signal V _REF (or the reference regulated voltage signal generated from the reference voltage signal V _REF ), the RS flip-flop 115 outputs the logic level The high control signal is sent to the pre-driver 121, and the gate control signal generated by the pre-driver 121 turns on the transistor M1 and turns off the transistor M2. In other words, when the addition result of the voltage signal V _COT and the feedback voltage FB is less than the reference voltage signal V _REF (or the reference regulated voltage signal generated from the reference voltage signal V _REF ), the off time of the buck converter Can be terminated.

The single-shot open circuit timer 114 receives the regulator input voltage V _IN and the regulator output voltage V _OUT , and generates the open circuit time control signal T _ON according to the regulator input voltage V _IN and the regulator output voltage V _OUT (as shown in Figures 2A and 2B Shown in) and an inverted signal of the open time control signal T _ON . The inverted signals of the open-circuit time control signal T _ON and the open-circuit time control signal T _ON are respectively input to the reset terminal and the set terminal of the RS flip-flop 115.

When the open-circuit time control signal T _{ON has a} low logic level, the RS flip-flop 115 outputs a high logic level control signal to the pre-driver 121, and the gate control signal generated by the pre-driver 121 turns on the transistor M2 and turns off the circuit. Crystal M1. In other words, when the addition result of the open-circuit time control signal T _ON is at a low logic level, the open-circuit time of the buck converter is terminated. Therefore, the fixed open-circuit time controller 11 can control the open-circuit time and the open-circuit time of the buck converter 12.

It should be noted that the implementation of the fixed open time controller 11 in FIG. 1 is not intended to limit the present invention. Other implementation aspects that can achieve the function of the fixed open-circuit time controller 11 can also be obtained by those skilled in the art with reference to the present invention. For example, in another embodiment, the RS flip-flop 15 can be replaced by another type of flip-flop.

1 and 2A, FIG. 2A is a circuit diagram of an embodiment of a single-shot open-circuit timer of the present invention. It is worth noting that FIG. 2A illustrates an embodiment of the single-shot open-circuit timer 114 of FIG. 1, and the present invention is not limited thereto. The single-shot open circuit timer 114 includes a hysteresis comparator 21, a resistor R ₁ and a capacitor C ₁ . The resistor R1 is electrically connected to the drain of the transistor M1 and the source of the transistor M2 to the voltage V _SW (that is, the voltage at one end of the energy storage inductor L _X ), and is further electrically connected to the ground through the capacitor C ₁ . The positive input terminal and the negative input terminal of the hysteresis comparator 21 are electrically connected to the regulator output voltage V _OUT and the connection point of the capacitor C ₁ and the resistor R ₁ , respectively.

The hysteresis comparator 21 compares the voltage across the capacitor C ₁ with the regulator output voltage V _OUT to output a hysteresis comparison result signal as the open-circuit time control signal T _ON . The voltage V _SW varies according to the regulator input voltage V _IN , the voltage across the capacitor C ₁ is generated according to the voltage V _SW , and the open time control signal T _ON is determined according to the voltage V _SW and the regulator output voltage V _OUT . In other words, the open time of the buck converter 12 is determined according to the regulator input voltage V _IN and the regulator output voltage V _OUT .

1 and FIG. B, FIG. 2B is a circuit diagram of another embodiment of a single-shot open-circuit timer of the present invention. It is worth noting that FIG. 2B illustrates another embodiment of the single-shot open-circuit timer 114 in FIG. 1, and the present invention is not limited thereto. The single-shot open-circuit timer 114 includes a current source 22, a voltage comparator 23, and a capacitor C _{T_ON} . The current source 22 is electrically connected to the supply voltage V _DD and the ground via the capacitor _{CT_ON} . The positive input terminal and the negative input terminal of the voltage comparator 23 are respectively electrically connected to the connection point of the current source 22 and the capacitor _{CT_ON} and the regulator output voltage V _OUT .

The current source 22 generates a current flowing through the capacitor C _{T_ON} according to the regulator input voltage V _IN , where the current is proportional to the regulator input voltage V _IN . The current flowing through the capacitor C _{T_ON} forms a voltage V _C across the capacitor C _{T_ON} , and the voltage comparator 23 compares the voltage V _C with the regulator output voltage V _OUT to generate a comparison result signal as the open-circuit time control signal T _ON . Therefore, the open time of the buck converter 12 is determined according to the regulator input voltage V _IN and the regulator output voltage V _OUT .

Next, referring to FIGS. 1 and 3, FIG. 3 is a circuit diagram of an embodiment of the current ripple extractor of the present invention. It is worth noting that FIG. 3 illustrates an embodiment of the current ripple extractor 111 in FIG. 1, and the present invention is not limited thereto. The current ripple extractor 111 includes a current sense amplifier 31, a sample-and-hold circuit 32 and a subtractor 33. An input terminal of the current sense amplifier 31 is electrically connected to the drain of the transistor M1 and the energy storage inductor L _X to receive the low-side current of the buck converter 12 (that is, the current I _SW ), and the current sense amplifier 31 The other input terminal is electrically connected to ground. An output terminal of the current sense amplifier 31 is electrically connected to the subtractor 33 and the sample-and-hold circuit 32. The subtractor 33 is electrically connected to the sample-and-hold circuit 32 and the comparator 113.

The current sense amplifier 31 is used to sense the current I _SW . The sensed current is generated by the current sense amplifier 31 and sent to the subtractor 33 and the sample-and-hold circuit 32. The DC component of the sensed current can be sampled and held by the sample and hold circuit 32. The subtractor 33 can subtract the held DC component (that is, the DC component of the previously sensed current) from the sensed current to generate an extracted ripple current, and the extracted ripple current outputs a ripple voltage signal. The subtractor 33 can further add the ramp voltage signal from the ramp generator 116 to the ripple voltage signal to form a voltage signal V _COT at the input terminal of the modulation circuit 113.

Next, referring to FIGS. 1 and 4A, FIG. 4A is a circuit diagram of an embodiment of the modulation circuit of the present invention. It is worth noting that FIG. 4A illustrates an embodiment of the modulation circuit 113 in FIG. 1, and the invention is not limited thereto. The modulation circuit 113 includes an amplifier 41, a capacitor C ₂ , an adder 42 and a modulator 43. An output terminal of the amplifier 41 is electrically connected to one end of the capacitor C ₂ . The two input terminals of the amplifier 41 are respectively electrically connected to the feedback voltage FB and the reference voltage signal V _REF . The other end of the capacitor C ₂ is electrically connected to the ground. Two input terminals of the modulator 43 are electrically connected to the feedback voltage FB and an output terminal of the adder 42 respectively, and an output terminal of the modulator 43 is electrically connected to the RS flip-flop 115. The two input terminals of the adder 42 are electrically connected to the voltage signal V _COT and the output terminal of the amplifier 41 respectively.

According to the feedback voltage FB and the reference voltage signal V _REF , the amplifier 41 generates the adjusted reference voltage signal V _REF '. The adder 42 subtracts the voltage signal V _COT from the adjusted reference voltage signal V _REF ′ to generate the voltage signal V _REFX . Then, the modulator 43 generates a modulating signal according to the voltage signal V _REFX and the feedback voltage FB.

It is worth noting that the amplifier 41 is used to adjust the reference voltage signal V _REF , so the accuracy will not be affected by the noise tolerance. However, the present invention is not limited to this. Referring to FIG. 4B, FIG. 4B is a circuit diagram of another embodiment of the modulation circuit of the present invention. In this embodiment, the amplifier 41 and the capacitor C2 in FIG. 4A are not included. Therefore, the adder 42 in FIG. 4B adds the reference voltage signal VREF and the voltage signal VCOT to generate the voltage signal VREFX, and the modulator 43 generates the modulation signal according to the voltage signal VREFX and the feedback voltage FB.

Next, referring to FIG. 1, FIG. 4A and FIG. 5. FIG. 5 is a signal waveform diagram of an embodiment of the buck converter device of the present invention. When the buck converter 12 is turned on, the current I _SW increases, and when the buck converter 12 is turned off, the current I _SW decreases. When the buck converter 12 is turned off, the voltage V _SW is positive and decreases, and when the buck converter 12 is turned off, the voltage V _SW is negative and increases.

The sensed current has a direct current component, and therefore the direct current component of the sensed current can be sampled and held according to the sample/hold trigger. The ripple current extractor 111 can subtract the held DC component of the sensed current from the currently sensed current to generate the extracted ripple current. The extracted ripple current and the reference voltage signal V _REF can be used to generate the above-mentioned comparison voltage signal V _REFX . The feedback voltage FB and the comparison voltage signal V _REFX can be used to determine the off time of the buck converter 12. In particular, when the feedback voltage FB is less than the comparison voltage signal V _REFX , the off time of the buck converter 12 will be terminated.

In summary, the present invention provides a fixed open-circuit time controller for use in a buck converter device, and provides a fixed open-circuit time controller which can obtain the extraction ripple through the sensing current of the ESR flowing through the output capacitor in the energy storage inductor The current, the extracted ripple current and the feedback voltage can be used to determine the off time of the buck converter. Because the extracted ripple current does not have a DC component, the fixed open-circuit time controller can have an enhanced noise tolerance. Furthermore, the signal fluctuation can also be improved by using the ramp voltage signal to compensate the slope of the extracted ripple current, and therefore the fixed open-circuit time controller has improved stability and noise immunity.

Although the present invention is described with specific embodiments, those skilled in the art can make modifications and changes without departing from the spirit of the present invention and within the scope defined by the patent application.

11: fixed open time controller

111: Current ripple extractor

112: Voltage divider

113: Modulation circuit

114: Single open timer

115: RS flip-flop

116: ramp generator

12: Buck converter

121: pre-driver

C _O : output capacitance

FB: Feedback voltage

I _SW : current

L _X : Energy storage inductance

M1, M2: Transistor

R _CO : output resistance

R _FBH , R _FBL : resistance

R _LOAD : output load

V _COT : Voltage signal

V _IN : Input voltage

V _REF : Reference voltage

V _OUT : output voltage

V _SW : Voltage

Claims (10)

A fixed open-circuit time controller includes: a voltage divider adapted to generate a feedback voltage according to the output voltage of a regulator of a buck converter; and a current ripple extractor adapted to sense the buck converter The equivalent series resistance (ESR) of an output capacitor in an energy storage inductor of the device, and is suitable for generating an extraction ripple current without a DC component based on a sensed current; A single-shot open-circuit timer, suitable for outputting a fixed open-circuit time control signal according to a regulator input voltage of the buck converter and the regulator output voltage; a modulation circuit electrically connected to the voltage divider And the current ripple extractor, suitable for outputting a modulation signal according to a reference voltage signal, the feedback voltage and the extracted ripple current; and a flip-flop, electrically connected to the single-shot open-circuit timer and The modulation circuit is suitable for generating a control signal to the buck converter according to the modulation signal and the fixed open time control signal; wherein an open time of the buck converter is based on the fixed open time control signal A cut-off time of the buck converter is determined based on the modulation signal. The fixed open-circuit time controller according to claim 1, wherein the flip-flop is a reset-set (RS) flip-flop, and a set terminal of the RS flip-flop is electrically connected to the comparison And the single-shot open-circuit timer to receive the comparison result signal and an inverted signal of the fixed open-circuit time control signal, and a reset terminal of the RS flip-flop is electrically connected to the single-shot open-circuit timer to receive the Fixed open circuit time control signal. The fixed open-circuit time controller according to claim 1, wherein the single-shot open-circuit timer includes: a capacitor; a resistor, which is electrically connected to the ground through the capacitor, and is adapted to receive a first end of the energy storage inductor Voltage, wherein the first voltage varies according to the regulator input voltage; and A hysteresis comparator is electrically connected to a connection end of the capacitor and the resistor, and compares a second voltage with the regulator output voltage at the connection end of the capacitor and the resistor to generate a hysteresis comparison result signal. As the fixed open time control signal. The fixed open-circuit time controller according to claim 1, wherein the single-shot open-circuit timer comprises: a capacitor; a current source, which is electrically connected to the ground via the capacitor, generates a current proportional to the input voltage of the regulator, To form a first voltage across the capacitor; and a voltage comparator, electrically connected to a connection end of the capacitor and the current source, to compare the regulator output voltage with the first voltage to output the fixed open time control Signal. The fixed open-circuit time controller according to claim 1, further comprising: a ramp generator electrically connected to the modulation circuit, suitable for generating a ramp voltage signal; wherein the modulation circuit is based on the feedback Voltage, the reference voltage signal, the ramp voltage signal and the extracted ripple current to output the modulation signal. The fixed open-circuit time controller according to claim 1, wherein the current ripple extractor comprises: a current sense amplifier adapted to sense the current in the energy storage inductor of the buck converter, which flows through the output The equivalent series resistance of the capacitor is used to obtain the sensed current; a sample and hold circuit, electrically connected to the current sense amplifier, suitable for sampling and holding the DC component of the sensed current; and a subtractor, It is electrically connected to the current sense amplifier and the sample-and-hold circuit, and is suitable for subtracting the held DC component from the sensed current to generate the extracted ripple current. The fixed open-circuit time controller according to claim 1, wherein the modulation circuit includes: An amplifier is adapted to receive the reference voltage signal and the feedback voltage to generate an adjusted reference voltage signal; a capacitor, both ends of which are electrically connected to the amplifier and ground; and an adder, electrically connected to the An amplifier, adapted to subtract the adjusted reference voltage signal from a first voltage signal associated with the extracted ripple current to generate a second voltage signal; and a modulator electrically connected to the adder, It is suitable for generating the modulation signal according to the second voltage signal and the feedback voltage. The fixed open time controller according to claim 1, wherein the modulation circuit includes: an adder adapted to generate a first voltage signal associated with the extracted ripple current by subtracting the reference voltage signal A second voltage signal; and a modulator, electrically connected to the adder, adapted to generate the modulated signal according to the second voltage signal and the feedback voltage. The fixed open time controller according to claim 1, wherein the voltage divider includes a plurality of resistors electrically connected in series. A buck converter device, comprising: the fixed open time controller according to any one of claims 1 to 9 and a buck converter, and the buck converter is electrically connected to the fixed open time controller , Where; the fixed open-circuit time controller includes: a voltage divider adapted to generate a feedback voltage according to the output voltage of a regulator of a buck converter; a current ripple extractor adapted to sense the A current in an energy storage inductor of the buck converter flows through the ESR of an output capacitor and is suitable for generating an extracted ripple current without a DC component based on a sensed current; A single-shot open-circuit timer, suitable for outputting a fixed open-circuit time control signal according to a regulator input voltage of the buck converter and the regulator output voltage; a modulation circuit electrically connected to the voltage divider And the current ripple extractor, suitable for outputting a modulation signal according to a reference voltage signal, the feedback voltage and the extracted ripple current; and a flip-flop, electrically connected to the single-shot open-circuit timer and The modulation circuit is suitable for generating a control signal to the buck converter according to the modulation signal and the fixed open time control signal; wherein an open time of the buck converter is based on the fixed open time control signal A cut-off time of the buck converter is determined based on the modulation signal.

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