CN113497544B - Switching power supply and its control circuit and fast response method - Google Patents

Abstract

A switching power supply and its control circuit and fast response method. The switching power supply has a load transient response capability, and includes at least one power stage circuit and a control circuit. The control circuit includes a pulse width modulation signal generating circuit and a fast response signal generating circuit. The pulse width modulation signal generating circuit generates a PWM signal according to the output voltage and the fast response signal, so as to operate the power switch in the corresponding power stage circuit to convert the input voltage into the output voltage. The fast response signal generating circuit includes a differentiating circuit and a comparing circuit. The differentiating circuit is used for performing a differential operation on the sensing signal related to the output voltage to generate a differential signal. The comparison circuit is used for comparing the differential signal with the fast response threshold signal, so as to determine the pulse width modulation signal generating circuit to execute the fast response procedure when the differential signal exceeds the fast response threshold signal.

Description

Switching power supply and its control circuit and fast response method

technical field

The present invention relates to a switching power supply, in particular to a switching power supply with load transient response capability. The invention also relates to a control circuit and a fast response method used in the switching power supply.

Background technique

FIG. 1A shows a prior art switching power supply 1 for converting an input voltage Vin into an output voltage Vout for supplying power to a central processing unit (CPU)/or a graphics processing unit (Graphic Processing Unit) , GPU) 10. As shown in FIG. 1A , the switching power supply 1 is a multi-phase switching power supply, which includes a plurality of power stage circuits 11 and a control circuit 12 . The control circuit 12 generates a corresponding pulse width modulation (PWM) according to the voltage sensing signal Vsense related to the output voltage Vout and the current sensing signals CS1 , CS2 and CS3 related to the inductor current flowing through the power stage circuits 11 . ) signals PWM1 , PWM2 and PWM3 respectively operate the power switches in the power stage circuit 11 to convert the input voltage Vin into the output voltage Vout.

Compared with the general switching power supply that does not supply power to the CPU or GPU, the switching power supply 1 has to meet the following special requirements: the CPU/GPU 10 is a load circuit whose power demand changes relatively rapidly during operation, and requires extremely high power consumption. To achieve dynamic voltage positioning with high precision, it needs to meet certain load line requirements, it needs to switch between different power consumption states relatively quickly, and it needs to provide different parameter measurement and monitoring. Communication between the switching power supply 1 and the CPU/GPU 10 is usually carried out through a serial bus interface, and the CPU/GPU 10 will provide different power requirements according to its load and operating mode.

Generally, the CPU/GPU 10 consumes a relatively large amount of current in certain operating modes, so a multi-phase power stage circuit 11 is often used. In the switching power supply 1 shown in FIG. 1A, there is a three-phase power stage circuit 11, and the power switches therein are operated according to the pulse width modulation (pulse width modulation, PWM) signals PWM1, PWM2 and PWM3 respectively, so as to input the input power. The voltage Vin is converted into the output voltage Vout. For the switching power supply 1, it is very important to accurately measure the current of each phase. The control circuit 12 maintains the current between the phases according to the current sensing signals CS1, CS2 and CS3 related to the current of each phase. Evenly distribute, and achieve good loop characteristic control, set the load line (load line), and enable the overcurrent protection program.

Please refer to FIG. 1B , which shows a schematic diagram of waveform signals of the voltage sensing signal Vsense and the PWM signals PWM1 , PWM2 and PWM3 in the droop operation mode of the switching power supply 1 . When the load increases, the output voltage Vout will drop. As shown in the figure, after the time point t1, the output voltage Vout will drop from the voltage V1 to the voltage V2. Also, in the initial stage when the output voltage Vout starts to drop from the voltage V1, undershoot occurs. When the load decreases, the output voltage Vout will rise (not shown, for example, the output voltage Vout will rise from the voltage V2 to the voltage V1), and at the initial stage of the output voltage Vout rising from the voltage V2, there will be an overshoot ( overshoot). Therefore, the voltage falling with load operation mode utilizes the load line technology, so that the output voltage Vout decreases when the load current increases, and increases the output voltage Vout when the load current decreases, thereby reducing the output capacitor Cout, and also That is, it is not necessary to use more output capacitors Cout with higher capacitance values, so as to reduce the circuit area and reduce the circuit manufacturing cost.

One of the disadvantages of the prior art switching power supply 1 is that when the load current increases, the undershoot of the output voltage Vout at the beginning of the drop occurs, the switching power supply 1 can only sense the voltage The feedback control of the signal Vsense produces as shown in FIG. 1B , the PWM signals PWM1 , PWM2 and PWM3 have relatively dense pulses during the period from the time point t1 to the time point t2 . In this control method, the load transient response capability is poor, resulting in a serious undershoot of the output voltage Vout. On the other hand, when the load is reduced, the prior art switchable power supply 1 causes severe overshoot in the initial stage of the rise of the output voltage Vout, which is also a disadvantage of the prior art.

That is, since the response speed of the prior art switching power supply 1 to load transients is limited, when the switching power supply 1 operates in a constant ON time mode, the constant ON time The on-time can only transmit a limited current, so it cannot meet the needs of heavy loads; and in the mechanism of the switching power supply 1 operating in the interleaving conduction mechanism, the dynamic response time is delayed, and multiple power stages In circuit 11, without simultaneous conduction, the idle phase cannot provide power for the load increase.

In view of this, the present invention proposes a switching power supply with load transient response capability in view of the above-mentioned deficiencies of the prior art. The invention also relates to a control circuit and a fast response method used in the switching power supply.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a switching power supply, comprising: at least one power stage circuit, wherein each power stage circuit is used for a corresponding pulse width modulation (pulse width modulation, PWM) signal, and operate one of the power switches to convert an input voltage into an output voltage; and a control circuit, including: a pulse width modulation signal generating circuit, coupled with the at least one power stage circuit, for according to the output voltage and a fast response signal to generate the PWM signal; and a fast response signal generating circuit coupled to the pulse width modulation signal generating circuit for generating the fast response signal according to the output voltage, the fast response signal generating The circuit includes: a differential circuit for performing a differential operation on a voltage sensing signal related to the output voltage to generate a differential signal; and a comparison circuit coupled with the differential circuit for comparing the differential The signal and a fast-response threshold signal are used to generate the fast-response signal, so that when the differential signal exceeds the fast-response threshold signal, the PWM signal generating circuit is determined to execute a fast-response procedure.

In another aspect, the present invention provides a control circuit used in a switching power supply to convert an input voltage into an output voltage, the control circuit comprising: a pulse width modulation signal generating circuit, wherein Each pulse width modulation signal generating circuit is coupled to the corresponding at least one power stage circuit for generating a PWM signal according to the output voltage and a fast response signal; and a fast response signal generating circuit, and the pulse The wide modulation signal generating circuit is coupled to generate the fast response signal according to the output voltage. The fast response signal generating circuit includes: a differential circuit for performing a voltage sensing signal related to the output voltage. differential operation to generate a differential signal; and a comparison circuit coupled to the differential circuit for comparing the differential signal with a fast response threshold signal to generate the fast response signal so that the differential signal exceeds the fast response threshold When the signal is detected, the pulse width modulation signal generating circuit is determined to execute a fast response procedure.

In a preferred embodiment, the fast-response signal generating circuit further includes a fast-response pulse generator coupled to the comparison circuit for generating a fast-response pulse signal according to the fast-response signal.

In a preferred embodiment, the switching power supply includes a plurality of power stage circuits, and in the fast response procedure, the pulse width modulation signal generating circuit adjusts each of the The PWM signal enables the corresponding power switch in each of the power stage circuits to simultaneously conduct a fast response period according to a fast response pulse signal related to the fast response signal.

In a preferred embodiment, the fast response threshold signal is determined according to an inductor current ripple signal, an output capacitor or/and the phase number of the at least one power stage circuit.

In a preferred embodiment, the switching power supply operates in a constant ON time mode.

In a preferred embodiment, the fast response threshold signal includes a positive fast response threshold or/and a negative fast response threshold.

In a preferred embodiment, when the switching power supply operates in a droop operation mode, the level of the output voltage drops and the differential signal exceeds the fast response threshold signal, the pulse width modulation signal generation circuit adjusts the PWM signal corresponding to each power stage circuit according to the fast response signal, so that a corresponding upper bridge power switch in each power stage circuit A fast-response pulse signal of the fast-response signal is simultaneously turned on for a period of fast-response.

In a preferred implementation, wherein when the switching power supply operates in a droop mode of operation, the level of the output voltage rises and the differential signal exceeds the fast response When the threshold signal is used, the pulse width modulation signal generation circuit adjusts the PWM signal corresponding to each power stage circuit according to the fast response signal, so that the corresponding lower bridge power switch in each power stage circuit A fast-response pulse signal of the fast-response signal is simultaneously turned on for a period of fast-response, or a corresponding upper-side power switch and the lower-side power switch in each of the power stage circuits are activated according to a signal related to the fast-response signal. Quickly respond to pulse signals, and do not conduct for a period of rapid response at the same time.

In a preferred embodiment, the PWM signal generating circuit also generates the PWM signal according to a voltage positioning signal, and adjusts the output voltage as follows:

Vout=VDAC-Iout*RLL

Wherein, Vout is the output voltage, VDAC is a required level related to the voltage positioning signal, Iout is an output current, and RLL is a load line resistance.

In a preferred embodiment, wherein the switching power supply operates in a droop operation mode, so that the PWM signal generating circuit is in a feedback loop, according to The output voltage and the fast response signal generate the PWM signal to convert the input voltage into the output voltage.

From another point of view, the present invention provides a fast response method for use in a switching power supply to improve load transient response capability, the fast response method comprising: responding to a voltage sense relative to an output voltage measure the signal, perform a differential operation, and generate a differential signal; compare the differential signal with a fast response threshold signal to generate a fast response signal, so that when the differential signal exceeds the fast response threshold signal, it is determined to execute a fast response program And in this fast response procedure, a pulse width modulation signal generation circuit in this switching power supply according to this fast response signal, adjust a pulse width modulation (pulse width modulation, PWM) signal, make this switch power supply A corresponding power switch in at least one power stage circuit in the device is turned on or off for a period of fast response according to a fast response pulse signal related to the fast response signal.

In a preferred embodiment, each power stage circuit in the at least one power stage circuit is used to operate the power switch according to the corresponding PWM signal to convert an input voltage into the output Voltage.

The following describes in detail through specific embodiments, and it should be easier to understand the purpose, technical content, characteristics and effects of the present invention.

Description of drawings

FIG. 1A shows a prior art switching power supply 1 .

FIG. 1B shows a schematic diagram of waveforms of the voltage sensing signal Vsense and the PWM signals PWM1, PWM2 and PWM3 of the switching power supply 1. As shown in FIG.

FIG. 2 shows a schematic diagram of an embodiment according to the present invention.

FIG. 3 shows a schematic diagram of the signal waveforms of the overshoot and the undershoot.

FIG. 4 shows a schematic diagram of a more specific embodiment according to the present invention.

Figure 5 shows a schematic diagram of the waveform of the correlation signal with a short period of fast response.

Figure 6 shows a schematic diagram of the waveform of the correlation signal with a long period of fast response.

FIG. 7 shows a schematic diagram of a signal waveform adaptively adjusted according to the duration of the differential signal exceeding the QR threshold signal during the fast response period.

FIG. 8 shows a schematic diagram of a waveform of a correlation signal with a preset fixed length during the fast response period.

FIG. 9 shows a schematic diagram of a signal waveform in which the fast-response pulse of the PWM signal overlaps with the alternately alternating pulses.

Figures 10A-10J show synchronous or asynchronous buck, boost, backpressure, buck-boost, and boost-backpressure power stage circuits.

Description of symbols in the figure

1, 2, 3: Switching power supply

10: CPU or Graphics Processor

11, 21, 31: Power Stage Circuits

12, 22, 32: Control Circuits

23, 33: PWM signal generation circuit

24, 34: QR signal generation circuit

241, 341: Differential Circuits

243, 343, 335: Comparison Circuits

331: Amplifier circuit

333: Summation Circuits

337: Alternating circuit between phases

345: QR Pulse Generator

Ai: summed current signal

Comp: Compare signal

Cout: output capacitance

CS1, CS2, CS3: Current Sense Signals

EAout: Amplify the output signal

Isense1, Isense2, Isense3: Current sensing signals

Ip, Ip2, Ip3: Phase current

LG: Lower Bridge Power Switch

Prdth: Duration

PWM1, PWM2, PWM3: PWM signals

t1, t2: time points

QRpulse: QR pulse signal e

QRprd1, QRprd2, QRprd3, QRprd4, QRprd5: During rapid response

QRsig: QR signal

QRth: QR threshold signal

UG: Upper bridge power switch

VDAC: required level

Vdiff: differentiated signal

Vin: input voltage

Vout: output voltage

Vsense: Voltage sense signal

Detailed ways

The drawings in the present invention are schematic diagrams, mainly intended to show the coupling relationship between the circuits and the relationship between the signal waveforms, and the circuits, signal waveforms and frequencies are not drawn to scale.

FIG. 2 shows an embodiment of a switching power supply (switching power supply 2 ) according to the present invention. The switching power supply 2 includes a power stage circuit 21 and a control circuit 22 . The power stage circuit 21 is used for operating a power switch (not shown) according to a corresponding pulse width modulation (PWM) signal PWM1 to convert the input voltage Vin into the output voltage Vout. The control circuit 22 includes a pulse width modulation (PWM) signal generating circuit 23 and a quick response (quick response, QR) signal generating circuit 24 . The PWM signal generating circuit 23 is coupled to the power stage circuit 21 for generating the PWM signal PWM1 according to the output voltage Vout and the quick response (QR) signal QRsig. The QR signal generating circuit 24 is coupled to the PWM signal generating circuit 23 for generating the QR signal QRsig according to the output voltage Vout. The QR signal generation circuit 24 includes a differentiation circuit 241 and a comparison circuit 243 . The differentiating circuit 241 is used for performing a differentiation operation (in particular, a differentiation operation with respect to time variation) on the voltage sensing signal Vsense related to the output voltage Vout to generate a differentiated signal Vdiff. The comparing circuit 243 is coupled to the differentiating circuit 241 for comparing the differential signal Vdiff with the quick response (QR) threshold signal QRth to generate the QR signal QRsig, so as to determine the PWM signal when the differential signal Vdiff exceeds the QR threshold signal QRth The generation circuit 23 performs a quick response (QR) procedure.

According to the present invention, the power stage circuit 21 may be configured as, for example, but not limited to, a synchronous or asynchronous buck, boost, inverse, or buck-boost power conversion circuit, as shown in Figures 10A-10J. The number of the power stage circuits 21 is not limited to a singular number, but may also be plural, which will be described in detail later. It should be noted that the so-called QR procedure refers to a response procedure for improving the undershoot and overshoot caused by load transients when the switchable power supply 2 is in the voltage falling operation mode. As mentioned above, an undershoot occurs when the output voltage Vout drops from a high level to a low level; and an overshoot occurs when the output voltage Vout rises from a low level to a high level. Typical overshoot and undershoot, as shown in the signal waveform diagram in Figure 3. Among them, the voltage V1 represents a higher potential, and the voltage V2 represents a lower potential.

FIG. 4 shows a schematic diagram of a more specific embodiment according to the present invention. As shown in the figure, the switching power supply 3 includes a plurality of power stage circuits 31 and a control circuit 32 . Each power stage circuit 31 is used to operate the power switch (for example, the upper bridge power switch UG and the lower bridge power switch in the power stage circuit shown in FIGS. 10A-10J ) according to the corresponding PWM signal PWM1 , PWM2 or PWM3 LG) to convert the input voltage Vin to the output voltage Vout. The control circuit 32 includes a PWM signal generating circuit 33 and a QR signal generating circuit 34 . The PWM signal generating circuit 33 is coupled to the power stage circuit 31 for generating the PWM signal PWM1 according to the output voltage Vout and the quick response (QR) signal QRsig. The QR signal generating circuit 34 is coupled to the PWM signal generating circuit 33 for generating the QR signal QRsig according to the output voltage Vout.

The QR signal generating circuit 34 includes a differentiating circuit 341 , a comparing circuit 343 and a quick response (quick response, QR) pulse generator 345 . The differentiating circuit 341 is used for performing a differentiation operation on the voltage sensing signal Vsense related to the output voltage Vout to generate a differentiated signal Vdiff. The comparing circuit 343 is coupled to the differentiating circuit 341 for comparing the differential signal Vdiff with the QR threshold signal QRth to generate the QR signal QRsig, so as to determine the PWM signal generating circuit 33 to perform a quick response (quick response) when the differential signal Vdiff exceeds the QR threshold signal QRth. response, QR) program. Compared with the embodiment shown in FIG. 2 , in this embodiment, the QR signal generating circuit 34 further includes a QR pulse generator 345 coupled to the comparing circuit 343 for generating a quick response according to the QR signal QRsig. , QR) pulse signal QRpulse.

The switching power supply 3 is a multi-phase switching power supply, and includes a plurality of power stage circuits 31 . In the fast response procedure of the switching power supply 3, the PWM signal generation circuit 33 adjusts each of the PWM signals PWM1, PWM2 and PWM3 according to the QR signal QRpulse, so that the corresponding power switch in each power stage circuit 31 is adjusted according to the QR signal. The QR pulse signal QRpulse of the signal QRsig is turned on or off for a period of fast response at the same time.

As shown in the figure, the PWM signal generating circuit 33 includes an amplifier circuit 331 , a summation circuit 333 , a comparison circuit 335 , and an interphase alternation circuit 337 . The amplifying circuit 331 generates the amplified output signal EAout according to the voltage sensing signal Vsense related to the output voltage Vout and the required level VDAC related to the voltage positioning signal. The summation circuit 333 generates the summed current signal Ai based on the phase currents Ip, Ip2 and Ip3 associated with each power stage. The comparison circuit 335 compares the amplified output signal EAout with the sum current signal Ai to generate the comparison signal Comp. The inter-phase alternating circuit 337 generates the PWM signals PWM1 and PWM2 respectively according to the comparison signal Comp, the QR pulse signal QRpulse related to the QR signal QRsig, and the current sensing signals Isense1, Isense2 and Isense3 corresponding to the currents Ip, Ip2 and Ip3 of each phase. with PWM3.

For example, the switching power supply 3 operates in a constant ON time mode, operates in a droop operation mode, and operates in an interleaving conduction mechanism . The PWM signal generating circuit 33 generates PWM signals PWM1, PWM2 and PWM3 according to the voltage identification (VID) signal, and the output voltage is adjusted by the following formula:

Vout=VDAC-Iout*RLL

Wherein, Vout is the output voltage Vout, VDAC is the required level VDAC related to the voltage positioning signal, Iout is the output current Iout, and RLL is the load line resistance.

In the droop operation mode, the PWM signal generating circuit 33 generates the PWM signals PWM1, PWM2 and PWM3 according to the output voltage Vout and the QR signal QRsig in the feedback loop, and converts the input voltage Vin is the output voltage Vout.

It should be noted that the so-called constant ON time mode refers to the power switch being turned on due to the feedback mechanism of adjusting the output voltage Vout (not due to the QR procedure) in each switching cycle of the PWM signal. The time is fixed, and this mode is called a fixed on-time mode, which is well known to those skilled in the art, and will not be repeated here. It should be noted that the mechanism of alternating conduction between phases.

It should be noted that the so-called interleaving conduction mechanism refers to that when the switching power supply includes multiple power stage circuits, the power switches in these power stage circuits can be controlled by PWM signals, and Interleaved conduction or conduction at the same time, so that each power stage circuit can share the output power to meet the needs of the load circuit with high power consumption, and reduce the ripple of the input voltage and output voltage, so as to reduce the volume and output of the inductance. Capacitance value of the capacitor.

In these operation modes, the differentiating circuit 341 in the QR signal generating circuit 34 performs a differentiating operation on the voltage sensing signal Vsese with respect to the output voltage Vout. The voltage sensing signal Vsese is, for example, but not limited to, the output voltage Vout itself, and can also be generated through other conversions. For example, when the output voltage Vout drops from a higher voltage V1 to a lower voltage V2, as shown in the diagram of the signal waveform of the output voltage Vout; the capacitor across the voltage Vc in the differentiating circuit 341 will be as small as The schematic diagram of the signal waveform of the capacitor voltage Vc shown in the figure; after the differential operation in the differential circuit 341, the schematic diagram of the signal waveform of the differential signal Vdiff as shown in the small figure is generated.

The comparison circuit 343 compares the differential signal Vdiff with the QR threshold signal QRth to generate a QR signal QRsig. The QR pulse generator 345 generates a QR pulse signal QRpulse based on the QR signal QRsig. In a preferred embodiment, when the switching power supply 3 operates in a droop mode of operation, the output voltage Vout drops from a higher level (eg, voltage V1 ) to a lower level When the level (such as the voltage V2) and the differential signal Vdiff exceeds the QR threshold signal QRth, the PWM signal generation circuit 33 adjusts the PWM signals PWM1, PWM2 and PWM3 corresponding to each power stage circuit 31 according to the QR signal QRsig, so that each The corresponding high-side power switch in the power stage circuit 31 (refer to the high-side power switch UG in FIGS. 10A-10J ) is simultaneously turned on for a period of fast response according to the QR pulse signal QRpulse related to the QR signal QRsig.

In another preferred embodiment, when the switching power supply 3 operates in the voltage falling operation mode, the output voltage Vout rises from a lower level (eg, the voltage V2 ) to a higher level (eg voltage V1), and when the differential signal Vdiff exceeds the QR threshold signal QRth, the PWM signal generation circuit 33 adjusts the PWM signals PWM1, PWM2 and PWM3 corresponding to each power stage circuit 31 according to the QR signal QRsig, so that each power stage The corresponding lower bridge power switch in the circuit 31 (refer to the lower bridge power switch LG in FIGS. 10A-10J ), according to the QR pulse signal QRpulse related to the QR signal QRsig, simultaneously conducts a period of fast response, or enables each power stage The corresponding upper-side power switch and lower-side power switch in the circuit 31 (refer to the upper-side power switch UG and the lower-side power switch LG in FIGS. 10A-10J ), according to the QR pulse signal QRpulse related to the QR signal QRsig, are not at the same time. Turn on for a period of fast response. Among them, in the upper bridge power switch and the lower bridge power switch (refer to the upper bridge power switch UG and the lower bridge power switch LG in Figs. 10A-10J ), according to the QR pulse signal QRpulse related to the QR signal QRsig, they are not conducting at the same time. In the embodiment with a fast response period, the tri-state of the upper and lower bridge power switches is used to turn on the parasitic diodes of the lower bridge switches, which can more effectively alleviate the overshoot of the output voltage Vout.

One of the technical features of the present invention over the prior art is that the voltage sensing signal Vsense related to the output voltage Vout is differentiated to calculate the rising or falling slope of the output voltage Vout, and according to the calculated result, the voltage sensing signal Vsense is turned on or simultaneously The corresponding power switch in each power stage circuit 31 is not turned on to mitigate overshoot or undershoot in response to load transients.

It should be noted that, according to the present invention, the pulse width of the QR pulse signal QRpulse is determined in two ways, for example, and the pulse width of the QR pulse signal QRpulse further determines the length of the fast response period. One determines the pulse width of the QR pulse signal QRpulse, which is a fixed pulse width, that is, as long as the differential signal Vdiff exceeds the QR threshold signal QRth, the pulse width of the generated QR pulse signal QRpulse is fixed, regardless of whether the differential signal Vdiff exceeds QR. The length of the period during which the threshold signal QRth lasts. The second method of determining the pulse width of the QR pulse signal QRpulse is to adaptively adjust the pulse width according to the length of the period during which the differential signal Vdiff exceeds the QR threshold signal QRth. That is, when the differential signal Vdiff exceeds the QR threshold signal QRth, The pulse width of the generated QR pulse signal QRpulse is determined according to the length of the period during which the differential signal Vdiff exceeds the QR threshold signal QRth.

It should be noted that, in a preferred embodiment, the QR threshold signal QRth is determined according to the inductor current ripple signal, the output capacitor Cout or/and the phase number of the power stage circuit 31 . The so-called inductor current ripple signal especially refers to the rising/falling slope of the inductor current ripple signal flowing through the inductor in each power stage circuit 31, which is at least related to the input voltage Vin, the output voltage Vout and the inductance value of the inductor .

It should be noted that the QR threshold signal QRth includes a positive fast response threshold or/and a negative fast response threshold. That is, the QR threshold signal QRth includes a positive fast response threshold value or/and a negative fast response threshold value, and can respond to the undershoot or/and the overshoot of the output voltage Vout.

FIG. 5 shows a waveform diagram of the correlation signal when QRprd1 is relatively short during the fast response period, in one embodiment. In one embodiment, for example, when the output voltage Vout drops from a higher level (eg, voltage V1 ) to a lower level (eg, voltage V2 ), and the differential signal Vdiff exceeds the QR threshold signal QRth, The PWM signal generating circuit 33 adjusts the PWM signals PWM1, PWM2 and PWM3 corresponding to each power stage circuit 31 according to the QR signal QRsig, so that the corresponding upper bridge power switch in each power stage circuit 31 (refer to FIGS. 10A-10J ) The upper bridge power switch UG), according to the QR pulse signal QRpulse related to the QR signal QRsig, simultaneously conducts a period of fast response QRprd1. Figure 5 shows that QRprd1 is relatively short during the fast response period, resulting in insufficient undershoot compensation, and the output voltage Vout still undershoots.

FIG. 6 shows a schematic diagram of the waveform of the correlation signal when QRprd2 is relatively long during the fast response period, in one embodiment. In one embodiment, for example, when the output voltage Vout drops from a higher level (eg, voltage V1 ) to a lower level (eg, voltage V2 ), and the differential signal Vdiff exceeds the QR threshold signal QRth, The PWM signal generating circuit 33 adjusts the PWM signals PWM1, PWM2 and PWM3 corresponding to each power stage circuit 31 according to the QR signal QRsig, so that the corresponding upper bridge power switch in each power stage circuit 31 (refer to FIGS. 10A-10J ) The upper bridge power switch UG), according to the QR pulse signal QRpulse related to the QR signal QRsig, simultaneously conducts a period of fast response QRprd2. FIG. 6 shows the case where QRprd2 is relatively long during the fast response period, so that the undershoot is overcompensated and the output voltage Vout produces a ringback condition.

FIG. 7 shows that in one embodiment, during the fast response period QRprd3 adaptively adjusts the relevant signals of the on-time of the upper bridge switch in each power stage circuit 13 according to the length of the Prdth period during which the differential signal Vdiff exceeds the QR threshold signal QRth Schematic diagram of the waveform. In one embodiment, for example, when the output voltage Vout drops from a higher level (eg, voltage V1 ) to a lower level (eg, voltage V2 ), and the differential signal Vdiff exceeds the QR threshold signal QRth, The pulse width of the QR pulse signal QRpulse is determined according to the length of the duration Prdth during which the differential signal Vdiff exceeds the QR threshold signal QRth. The corresponding PWM signals PWM1, PWM2 and PWM3 in each power stage circuit 31 make the corresponding upper-bridge power switch (refer to the upper-bridge power switch UG in FIGS. 10A-10J ), according to the pulse width of the QR pulse signal QRpulse, to turn on at the same time QRprd3 during a period of rapid response.

FIG. 8 shows a schematic waveform diagram of a correlation signal of a predetermined fixed length during the fast response period, QRprd4, in one embodiment. In one embodiment, for example, when the output voltage Vout drops from a higher level (eg, voltage V1 ) to a lower level (eg, voltage V2 ), and the differential signal Vdiff exceeds the QR threshold signal QRth, The pulse width of the QR pulse signal QRpulse, for example, is not determined according to the length of Prdth during which the differential signal Vdiff exceeds the QR threshold signal QRth, but when the differential signal Vdiff exceeds the QR threshold signal QRth, a pulse having a fixed preset pulse width is generated. QR pulse signal QRpulse, and make the PWM signal generation circuit 33 adjust the PWM signals PWM1, PWM2 and PWM3 corresponding to each power stage circuit 31 according to the pulse width of the QR pulse signal QRpulse, so that the corresponding upper The bridge power switch (refer to the upper bridge power switch UG in FIGS. 10A-10J ), according to the pulse width of the QR pulse signal QRpulse, simultaneously conducts a fast response period QRprd4 of a preset length.

FIG. 9 shows a schematic diagram of signal waveforms in which the fast-response pulses of the related PWM signal overlap with the alternate-phase pulses. As shown in FIG. 9, in the fast response period QRprd5, according to the QR pulse signal QRpulse, fast response pulses are generated in each of the PWM signals PWM1, PWM2 and PWM3. When the alternating pulses generated in each PWM signal PWM1, PWM2 and PWM3 (as shown by the dotted line in the figure) overlap, each PWM signal PWM1, PWM2 and PWM3 will be kept at a high level, that is, keep the corresponding power switch turned on. .

The present invention has been described above with respect to the preferred embodiments, but the above description is only for those skilled in the art to easily understand the content of the present invention, and is not intended to limit the scope of rights of the present invention. The described embodiments are not limited to be applied individually, but can also be applied in combination. For example, two or more embodiments can be applied in combination, and some components in one embodiment can also be used to replace those in another embodiment. corresponding components. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, for example, the present invention refers to "processing or computing according to a certain signal or generating a certain output result", Not limited to the signal itself, if necessary, the signal is subjected to voltage-to-current conversion, current-to-voltage conversion, and/or ratio conversion, etc., and then processed or calculated according to the converted signal to generate a certain output result. From this, it can be seen that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combinations, which are not listed and described here. Accordingly, the scope of the present invention should cover the above and all other equivalent changes.

Claims (27)

1. A switching power supply, comprising: a plurality of power stage circuits, each of which is used for operating one of the power switches according to a corresponding pulse width modulation signal to convert an input voltage into an output voltage; and a control circuit, comprising: a pulse width modulation signal generating circuit, coupled to at least one power stage circuit, for generating the pulse width modulation signal according to the output voltage and a fast response signal; and A quick-response signal generating circuit coupled to the PWM signal generating circuit for generating the quick-response signal according to the output voltage, the quick-response signal generating circuit comprising: a differential circuit for performing a differential operation on a voltage sensing signal related to the output voltage to generate a differential signal; and a comparison circuit coupled to the differentiation circuit for comparing the differential signal with a fast response threshold signal to generate the fast response signal, so as to determine the pulse width modulated signal when the differential signal exceeds the fast response threshold signal generating circuit to execute a quick response procedure; Wherein, in the fast response procedure, the pulse width modulation signal generating circuit adjusts each of the pulse width modulation signals according to the fast response signal, so that the corresponding power switch in each power stage circuit is adjusted according to the fast response signal. A fast response pulse signal of the response signal, which is turned on or off for a period of fast response at the same time; The pulse width of the fast response pulse signal determines the length of the fast response period, and the pulse width of the fast response pulse signal is determined according to the duration of the differential signal exceeding the fast response threshold signal. 2 . The switching power supply of claim 1 , wherein the fast-response signal generating circuit further comprises a fast-response pulse generator, coupled to the comparison circuit, for generating the fast-response signal according to the fast-response signal. 3 . Respond to pulsed signals. 3 . The switching power supply of claim 1 , wherein the fast response threshold signal is determined according to an inductor current ripple signal, an output capacitor or/and the number of phases of the plurality of power stage circuits. 4 . 4. The switching power supply of claim 1, wherein the switching power supply operates in a fixed on-time mode. 5 . The switching power supply of claim 1 , wherein the fast response threshold signal comprises a positive fast response threshold or/and a negative fast response threshold. 6 . 6 . The switching power supply of claim 1 , wherein, when the switching power supply operates in a voltage drop operation mode, the level of the output voltage drops and the differential signal exceeds the When responding to the threshold signal quickly, the pulse width modulation signal generating circuit adjusts the pulse width modulation signal corresponding to each power stage circuit according to the fast response signal, so that a corresponding upper bridge power switch in each power stage circuit , according to the fast response pulse signal related to the fast response signal, turn on the fast response period at the same time. 7 . The switching power supply of claim 1 , wherein when the switching power supply operates in a voltage falling operation mode, the level of the output voltage rises and the differential signal exceeds the When responding to the threshold signal quickly, the pulse width modulation signal generating circuit adjusts the pulse width modulation signal corresponding to each power stage circuit according to the fast response signal, so that the corresponding lower bridge power switch in each power stage circuit, According to the fast-response pulse signal related to the fast-response signal, turn on the fast-response period at the same time, or make a corresponding high-side power switch and the low-side power switch in each of the power stage circuits, according to the corresponding fast-response signal The fast-response pulse signal of the fast-response signal does not conduct the fast-response period at the same time. 8 . The switching power supply of claim 1 , wherein the switching power supply operates in a voltage fall with load operation mode, so that the pulse width modulation signal generating circuit is in a feedback loop, according to the output The voltage and the fast response signal generate the pulse width modulated signal, which converts the input voltage into the output voltage. 9. The switching power supply of claim 8, wherein the PWM signal generating circuit further generates the PWM signal according to a voltage positioning signal, and adjusts the output voltage by the following formula: Vout=VDAC-Iout*RLL Wherein, Vout is the output voltage, VDAC is a required level related to the voltage positioning signal, Iout is an output current, and RLL is a load line resistance. 10. A control circuit for use in a switching power supply to convert an input voltage into an output voltage, the control circuit comprising: a pulse width modulation signal generating circuit coupled to at least one power stage circuit for generating a pulse width modulation signal according to the output voltage and a fast response signal; and A quick-response signal generating circuit coupled to the PWM signal generating circuit for generating the quick-response signal according to the output voltage, the quick-response signal generating circuit comprising: a differential circuit for performing a differential operation on a voltage sensing signal related to the output voltage to generate a differential signal; and a comparison circuit coupled to the differentiation circuit for comparing the differential signal with a fast response threshold signal to generate the fast response signal, so as to determine the pulse width modulated signal when the differential signal exceeds the fast response threshold signal generating circuit to execute a quick response procedure; Wherein, in the fast response procedure, the pulse width modulation signal generating circuit adjusts each of the pulse width modulation signals according to the fast response signal, so that the corresponding power switch in each power stage circuit can be adjusted according to the fast response signal. A fast-response pulse signal of the signal, which is turned on or off for a period of fast-response at the same time; The pulse width of the fast response pulse signal determines the length of the fast response period, and the pulse width of the fast response pulse signal is determined according to the duration of the differential signal exceeding the fast response threshold signal. 11. The control circuit of claim 10, wherein the fast response signal generating circuit further comprises a fast response pulse generator coupled to the comparison circuit for generating the fast response pulse signal according to the fast response signal . 12. The control circuit of claim 10, wherein the fast response threshold signal is determined according to an inductor current ripple signal, an output capacitor or/and the number of phases of a plurality of power stage circuits. 13. The control circuit of claim 10, wherein the switching power supply operates in a fixed on-time mode. 14. The control circuit of claim 10, wherein the fast response threshold signal comprises a positive fast response threshold or/and a negative fast response threshold. 15 . The control circuit of claim 10 , wherein when the switching power supply operates in a voltage fall with load operation mode, the level of the output voltage drops and the differential signal exceeds the fast response threshold. 16 . signal, the pulse width modulation signal generation circuit adjusts the pulse width modulation signal corresponding to each of the power stage circuits according to the fast response signal, so that a corresponding upper bridge power switch in each power stage circuit, according to the relevant During the fast response pulse signal of the fast response signal, the fast response period is turned on at the same time. 16 . The control circuit of claim 10 , wherein when the switching power supply operates in a voltage falling operation mode, the output voltage level rises and the differential signal exceeds the fast response threshold. 17 . signal, the pulse width modulation signal generation circuit adjusts the pulse width modulation signal corresponding to each power stage circuit according to the fast response signal, so that the corresponding lower bridge power switch in each power stage circuit The fast-response pulse signal of the fast-response signal is simultaneously turned on for a period of fast-response, or a corresponding upper-side power switch and the lower-side power switch in each of the power stage circuits, A fast-response pulse signal is not turned on during the fast-response period at the same time. 17. The control circuit as claimed in claim 10, wherein the switching power supply operates in a voltage falling operating mode, so that the PWM signal generating circuit is in a feedback loop, according to the output voltage and the The pulse width modulated signal is generated in response to a fast signal, and the input voltage is converted into the output voltage. 18. The control circuit of claim 17, wherein the PWM signal generating circuit further generates the PWM signal according to a voltage positioning signal, and adjusts the output voltage by the following formula: Vout=VDAC-Iout*RLL Wherein, Vout is the output voltage, VDAC is a required level related to the voltage positioning signal, Iout is an output current, and RLL is a load line resistance. 19. A fast response method for use in a switching power supply to improve load transient response capability, the fast response method comprising: performing a differential operation on a voltage sensing signal related to an output voltage to generate a differential signal; comparing the differential signal with a fast-response threshold signal to generate a fast-response signal, so as to determine to execute a fast-response procedure when the differential signal exceeds the fast-response threshold signal; and In the fast response procedure, a pulse width modulation signal generating circuit in the switching power supply adjusts a pulse width modulation signal according to the fast response signal, so that the power stage circuits in the switching power supply the plurality of power switches, according to a fast response pulse signal related to the fast response signal, turn on or off for a period of fast response; The pulse width of the fast response pulse signal determines the length of the fast response period, and the pulse width of the fast response pulse signal is determined according to the duration of the differential signal exceeding the fast response threshold signal. 20. The fast response method as claimed in claim 19, wherein each power stage circuit of the plurality of power stage circuits is used to operate the power switch according to the corresponding PWM signal to switch a The input voltage is converted to this output voltage. 21. The fast response method of claim 19, wherein the fast response threshold signal is determined according to an inductor current ripple signal, an output capacitor or/and the number of phases of the plurality of power stage circuits. 22. The fast response method of claim 19, wherein the switching power supply operates in a fixed on-time mode. 23. The fast response method of claim 19, wherein the fast response threshold signal comprises a positive fast response threshold or/and a negative fast response threshold. 24. The fast response method of claim 19, wherein when the switching power supply operates in a voltage drop operation mode, the level of the output voltage drops, and the differential signal exceeds the fast response When the threshold signal is used, the pulse width modulation signal generating circuit adjusts the pulse width modulation signal corresponding to each power stage circuit according to the fast response signal, so that a corresponding upper bridge power switch in each power stage circuit is The fast-response pulse signal related to the fast-response signal is simultaneously turned on during the fast-response period. 25. The fast response method as claimed in claim 19, wherein when the switching power supply operates in a voltage falling operation mode, the level of the output voltage rises and the differential signal exceeds the fast response When the threshold signal is used, the pulse width modulation signal generation circuit adjusts the pulse width modulation signal corresponding to each power stage circuit according to the fast response signal, so that the corresponding lower bridge power switch in each power stage circuit can be adjusted according to the relevant During the fast-response pulse signal of the fast-response signal, turn on the fast-response period at the same time, or make a corresponding high-side power switch and the low-side power switch in each of the power stage circuits, according to the relation to the fast-response The fast response pulse signal of the signal is not turned on during the fast response period at the same time. 26. The fast response method as claimed in claim 19, wherein the switching power supply operates in a voltage falling operation mode, so that the pulse width modulation signal generating circuit is in a feedback loop, according to an output voltage and The fast response signal generates the pulse width modulated signal to convert the input voltage to the output voltage. 27. The fast response method of claim 26, wherein the PWM signal generating circuit further generates the PWM signal according to a voltage positioning signal, and adjusts the output voltage by the following formula: Vout=VDAC-Iout*RLL Wherein, Vout is the output voltage, VDAC is a required level related to the voltage positioning signal, Iout is an output current, and RLL is a load line resistance.

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