Transient response circuit, switching converter, chip and electronic equipment

Abstract

The invention relates to the technical field of switching power supplies, and relates to a transient response circuit, a switching converter, a chip and electronic equipment. The transient response circuit comprises a first adjusting unit, a second adjusting unit and an error amplifier, and the first adjusting unit and the second adjusting unit are both connected with the output end of the error amplifier. The first adjusting unit is used for controlling the first error voltage to be increased when the first error voltage output by the error amplifier is smaller than a first error voltage threshold value; the second adjusting unit is used for controlling the first error voltage to be increased when the first error voltage output by the error amplifier is greater than a second error voltage threshold value; the first error voltage threshold value is smaller than the second error voltage threshold value. Therefore, the problem that the load transient response circuit cannot work normally due to overshoot of the output voltage can be improved, and the stability of the circuit is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a transient response circuit, a switching converter, a chip and an electronic device. Background Art

[0002] A direct current / direct current (DC / DC) converter is a switching converter used to convert a direct current voltage into another direct current voltage. The essence of a DC / DC converter is a load transient response circuit that can convert one form of energy into another form of energy. Based on the energy storage characteristics of the inductor in the transient response circuit, the input electrical energy can be stored in the inductor through a controllable switch. When the controllable switch is disconnected, the electrical energy stored in the inductor can be released to provide energy to the load.

[0003] In some schemes, for a peak current mode DC / DC converter, a peak current mode DC / DC converter is a circuit that realizes power conversion by controlling current, and may include an error amplifier, etc. Among them, the error amplifier is used to amplify and process the error of the input signal and convert it into a voltage output. The sampling current of the peak current mode DC / DC converter will change with the change of the input voltage, and the output of the error amplifier will change accordingly to maintain the stability of the load transient response circuit. However, it takes a certain amount of time for the output of the error amplifier to change, and during this period of time, the output voltage will produce a certain overshoot, which refers to a peak voltage that exceeds the preset voltage. Output voltage overshoot will cause the load transient response circuit to fail to work properly and affect the stability of the circuit. Summary of the invention

[0004] In view of this, the present application provides a transient response circuit, a switching converter, a chip and an electronic device.

[0005] In a first aspect, the present application provides a transient response circuit, comprising a first adjustment unit, a second adjustment unit, and an error amplifier, wherein the first adjustment unit and the second adjustment unit are both connected to the output end of the error amplifier; the first adjustment unit is used to control the first error voltage to increase when the first error voltage output by the error amplifier is less than a first error voltage threshold; the second adjustment unit is used to control the first error voltage to decrease when the first error voltage output by the error amplifier is greater than a second error voltage threshold; the first error voltage threshold is less than the second error voltage threshold.

[0006] Based on the above scheme, in the transient response circuit provided in the embodiment of the present application, by adding a first adjustment unit in the output voltage undershoot stage to quickly charge the compensation capacitor so that the first error voltage increases, thereby increasing the output voltage and quickly alleviating the undershoot of the output voltage. In the output voltage overshoot stage, by adding a second adjustment unit, the compensation capacitor is quickly discharged so that the first error voltage decreases, thereby reducing the output voltage and quickly alleviating the overshoot of the output voltage. The transient response speed of the transient response circuit is fast, thereby improving the problem that the load transient response circuit cannot work normally due to the output voltage overshoot, thereby improving the stability of the circuit.

[0007] In a possible implementation of the first aspect above, the transient response circuit also includes a compensation unit, the first adjustment unit includes a first switch tube and a first comparator, the first comparator is used to control the first switch tube to be turned on; the first adjustment unit is used to charge the compensation unit when the first switch tube is turned on, so that the first error voltage increases to control the output voltage of the transient response circuit to be not less than the first output voltage threshold.

[0008] In a possible implementation of the first aspect above, the compensation unit includes a first compensation capacitor, a second compensation capacitor and a first compensation resistor, the first end of the first switch tube is used to obtain the input voltage, the control end of the first switch tube is connected to the output end of the first comparator, the second end of the first switch tube is respectively connected to the first end of the second compensation capacitor and the first end of the first compensation resistor, the second end of the first compensation resistor is connected to the first end of the first compensation capacitor, and the second end of the first compensation capacitor and the second end of the second compensation capacitor are both grounded.

[0009] In some embodiments of the present application, the first end of the first switch tube may refer to the source of the first switch tube mentioned in the embodiments of the present application, the control end of the first switch tube may refer to the gate of the first switch tube mentioned in the embodiments of the present application, and the second end of the first switch tube may refer to the drain of the first switch tube mentioned in the embodiments of the present application.

[0010] In a possible implementation of the first aspect above, the second regulating unit includes a second switching tube and a second comparator, and the second comparator is used to control the conduction of the second switching tube; the second regulating unit is used to discharge the compensation unit when the second switching tube is turned on, so that the first error voltage is reduced to control the output voltage of the transient response circuit to be no greater than the second output voltage threshold.

[0011] In a possible implementation of the first aspect above, the first end of the second switch tube is grounded, the control end of the second switch tube is connected to the output end of the second comparator, the second end of the second switch tube is respectively connected to the first end of the second compensation capacitor and the first compensation resistor, and the second end of the first compensation resistor is connected to the first compensation capacitor.

[0012] In some embodiments of the present application, the first end of the second switch tube may refer to the source of the second switch tube mentioned in the embodiments of the present application, the control end of the second switch tube may refer to the gate of the second switch tube mentioned in the embodiments of the present application, and the second end of the second switch tube may refer to the drain of the second switch tube mentioned in the embodiments of the present application.

[0013] In a possible implementation of the first aspect above, the first comparator is used to output a low-level signal, and the gate voltage of the first switch tube is less than the source voltage of the first switch tube, so that the first switch tube is turned on.

[0014] In a possible implementation of the first aspect above, the second comparator is used to output a high-level signal, and the gate voltage of the second switch tube is greater than the source voltage of the second switch tube, so that the second switch tube is turned on.

[0015] In a possible implementation of the first aspect above, the transient response circuit also includes a pulse width comparator, a driving unit, a third switch tube and a fourth switch tube, the pulse width comparator is used to control the driving unit to drive the third switch tube or the fourth switch tube to turn on; the first input end of the pulse width comparator is respectively connected to the output end of the error amplifier, the first adjustment unit and the second adjustment unit, the output end of the pulse width comparator is connected to the input end of the driving unit, the first output end of the driving unit is connected to the control end of the third switch tube, the second output end of the driving unit is connected to the control end of the fourth switch tube, and the first end of the third switch tube and the first end of the fourth switch tube are respectively connected to the first end of the inductor, the second end of the inductor is connected to the input voltage end, the second end of the third switch tube is grounded, and the second end of the fourth switch tube is connected to the output voltage end; the pulse width comparator is used to obtain the first error voltage, and control the driving unit to drive the third switch tube or the fourth switch tube to turn on based on the first error voltage.

[0016] It can be understood that the control end of the third switch tube can refer to the gate of the third switch tube S3 mentioned in the embodiment of the present application, the first end of the third switch tube can refer to the source of the third switch tube S3 mentioned in the embodiment of the present application, and the second end of the third switch tube can refer to the drain of the third switch tube S3 mentioned in the embodiment of the present application. And, the control end of the fourth switch tube can refer to the gate of the fourth switch tube S4 mentioned in the embodiment of the present application, the first end of the fourth switch tube can refer to the source of the fourth switch tube S4 mentioned in the embodiment of the present application, and the second end of the fourth switch tube can refer to the drain of the fourth switch tube S4 mentioned in the embodiment of the present application.

[0017] In a possible implementation of the first aspect above, when the first error voltage is controlled to increase based on the first adjustment unit, the pulse width comparator outputs a first pulse width signal, and the driving unit controls the third switch tube to turn on based on the first pulse width signal, so that the output voltage of the transient response circuit is not less than the first output voltage threshold; when the first error voltage is controlled to decrease based on the second adjustment unit, the pulse width comparator outputs a second pulse width signal, and the driving unit controls the fourth switch tube to turn on based on the second pulse width signal, so that the output voltage of the transient response circuit is not greater than the second output voltage threshold.

[0018] In a second aspect, the present application provides a switching converter, comprising the transient response circuit provided by the above-mentioned first aspect and various possible implementations of the first aspect.

[0019] In a third aspect, the present application provides a chip, comprising the transient response circuit provided by the above-mentioned first aspect and various possible implementations of the first aspect.

[0020] In a fourth aspect, the present application provides an electronic device, comprising the transient response circuit provided by the first aspect and various possible implementations of the first aspect, a switching converter provided by the second aspect, and a chip provided by the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 According to some embodiments of the present application, a schematic diagram of a transient response circuit 10 is shown;

[0022] Figure 2 According to some embodiments of the present application, a schematic diagram of a process of transient response of an output voltage is shown;

[0023] Figure 3 According to some embodiments of the present application, a schematic diagram of a transient response circuit 20 is shown. DETAILED DESCRIPTION

[0024] Illustrative embodiments of the present application include, but are not limited to, a transient response circuit, a switching converter, a chip, and an electronic device.

[0025] The specific implementation process of the technical solution provided in the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0026] It can be understood that the transient response circuit of the embodiment of the present application can be applied to a switching converter in any electronic device and is not limited here.

[0027] As mentioned above, in some schemes, for a peak current mode DC / DC converter, a peak current mode DC / DC converter is a circuit that realizes power conversion by controlling current, and its circuit structure may include circuits such as an error amplifier, and the error amplifier can be used to amplify and process the error of the input signal and convert it into a voltage output. Among them, the sampling current of the peak current mode DC / DC converter will change with the change of the input voltage, and the output of the error amplifier will also change accordingly to maintain the stability of the circuit. Since the output change of the error amplifier takes a certain amount of time, the output voltage will have a certain overshoot during this period of time. However, the output voltage overshoot will cause the load circuit to fail to work normally, affecting the stability of the circuit.

[0028] It can be understood that when the load changes suddenly, the output voltage will overshoot, and the output voltage overshoot includes output voltage upshoot and output voltage undershoot. For example, when the load suddenly changes from heavy load to light load, less current is needed to meet the load demand, resulting in an instantaneous rise in the output voltage, that is, the output voltage upshoot, and the output voltage instantaneously exceeds the set value. For another example, when the load suddenly changes from light load to heavy load, more current is needed to meet the load demand, resulting in an instantaneous drop in the output voltage, that is, the output voltage undershoot, and the output voltage is instantaneously lower than the set value. Moreover, whether the output voltage overshoots or the output voltage undershoots, it will cause damage to other components in the circuit and affect the normal operation of the circuit.

[0029] It can be understood that the error amplifier is used to amplify and process the error of the input signal and convert it into a voltage output. The error amplifier usually has two input terminals, namely the non-inverting input terminal (+) and the inverting input terminal (-). Among them, the non-inverting input terminal (+) is used to receive the output signal of the circuit or other signals that need to be compared as input. The inverting input terminal (-) is used to receive the reference signal of the circuit as input, and the inverting input terminal (-) is usually connected to a stable reference voltage source, which is used as a reference value for the error amplifier. In addition, by comparing the difference between the input signals of the non-inverting input terminal (+) and the inverting input terminal (-), the error amplifier can generate an error signal, and then the output voltage of the circuit can be adjusted according to this error signal to achieve control and regulation of the system.

[0030] In order to solve the above problems, the present application provides a transient response circuit, which includes a first adjustment unit, a second adjustment unit, and an error amplifier. The first adjustment unit and the second adjustment unit are both connected to the output end of the error amplifier; the first adjustment unit is used to control the first error voltage to increase when the first error voltage output by the error amplifier is less than the first error voltage threshold; the second adjustment unit is used to control the first error voltage to decrease when the first error voltage output by the error amplifier is greater than the second error voltage threshold; the first error voltage threshold is less than the second error voltage threshold.

[0031] Based on the above scheme, in the transient response circuit provided in the embodiment of the present application, by adding a first regulating unit, in the output voltage undershoot stage, the compensation capacitor in the error amplifier is quickly charged so that the first error voltage increases, thereby increasing the output voltage, and quickly alleviating the undershoot of the output voltage. By adding a second regulating unit, in the output voltage overshoot stage, the compensation capacitor is quickly discharged so that the first error voltage decreases, thereby reducing the output voltage, and quickly alleviating the overshoot of the output voltage. The transient response speed of the transient response circuit is fast, thereby improving the problem that the load transient response circuit cannot work normally due to the output voltage overshoot, thereby improving the stability of the circuit.

[0032] The transient response circuit mentioned in this application is introduced in detail below. Figure 1 FIG. 1 shows a circuit diagram of a transient response circuit 10. Figure 1 The transient response circuit 10 shown may include a power circuit portion and a control circuit portion.

[0033] The power circuit part includes: an inductor L1, a third switch tube S3 and a fourth switch tube S4. Among them, one end of the inductor L1 is connected to the input voltage terminal Vin, and the inductor L1 can be used to store electric energy; the source of the third switch tube S3 and the source of the fourth switch tube S4 are both connected to the other end of the inductor L1, the gate of the third switch tube S3 and the gate of the fourth switch tube S4 are respectively connected to the first output terminal and the second output terminal of the driving unit, the drain of the third switch tube S3 is grounded, the drain of the fourth switch tube S4 is respectively connected to one end of the output capacitor C3, the load resistor R2, and the voltage divider resistor R3 and connected to the output voltage terminal, the other ends of the output capacitor C3 and the load resistor R2 are grounded, and after the other end of the voltage divider resistor R3 is connected in series with the voltage divider resistor R4, the other end of the voltage divider resistor R4 is grounded.

[0034] The control circuit part may include an error amplifier, a pulse width comparator, a driving unit, a current sampling unit, a compensation unit, a first regulating unit, and a second regulating unit.

[0035] The first input terminal of the error amplifier is connected to the series connection of the voltage-dividing resistor R3 and the voltage-dividing resistor R4, the second input terminal of the error amplifier is connected to the reference power supply, and the output terminal of the error amplifier is connected to the first input terminal of the pulse width comparator. The first input terminal of the error amplifier can obtain the first feedback voltage VFB through the voltage-dividing network composed of the voltage-dividing resistor R3 and the voltage-dividing resistor R4; the second input terminal of the error amplifier can obtain the reference voltage Vref1 through the reference power supply, and then obtain the first error voltage Vea by comparing the first feedback voltage VFB with the reference voltage Vref1, and amplify it and output it to the first input terminal of the pulse width comparator.

[0036] The first input end of the pulse width comparator is connected to the output end of the error amplifier to obtain the first error voltage Vea, and the second input end of the pulse width comparator is connected to one end of the slope compensation unit and then to the current sampling unit to access the slope compensation signal Vslope and the current sampling signal Vsense. Then, the pulse width comparator compares the superposition signal of the first error voltage Vea and the slope compensation voltage signal Vslope with the current sampling signal Vsense to obtain a pulse width modulation signal and output it to the driving unit.

[0037] The first input terminal of the driving unit is connected to the output terminal of the pulse width comparator to obtain a pulse width modulation signal, the first output terminal of the driving unit is connected to the gate of the fourth switch tube S4, and the second output terminal of the driving unit is connected to the gate of the third switch tube S3. The driving unit is used to provide a switch drive signal to control the conduction and disconnection of S3 and S4. When the third switch tube S3 is turned on and the fourth switch tube S4 is turned off, the input voltage Vin flows through the inductor L1. At this time, the power supply VDD flows through the inductor L1, so that part of the electric energy is stored in the inductor L1; when the fourth switch tube S4 is turned on and the third switch tube S3 is turned off, part of the electric energy stored in the inductor L1 can be supplied to the output voltage terminal through the fourth switch tube S4. Among them, part of the electric energy will be stored on the output capacitor C3 and supply power to the load resistor.

[0038] One end of the current sampling unit is connected to the source of the third switch tube S3, the source of the fourth switch tube S4, and the second end of the inductor L1, and the other end of the current sampling unit is connected to one end of the slope compensation unit. The current sampling unit can be used to sample the inductor current IL and generate a current detection signal to output to the slope compensation unit, and then the slope compensation unit can generate a slope compensation voltage according to the current detection signal.

[0039] The compensation unit may include a first compensation capacitor C1, a second compensation capacitor C2, and a first compensation resistor R1. One end of the first compensation capacitor C1 and the second compensation capacitor C2 is grounded, and the other end of the first compensation capacitor C1 is connected to one end of the first compensation resistor R1 and then to the other end of the second compensation capacitor C2, and then connected to the first input end of the pulse width comparator. When the output voltage of the transient response circuit 10 overshoots or undershoots, the overshoot or undershoot of the output voltage can be quickly alleviated by charging and discharging C1 and C2 in the compensation unit, thereby improving the transient response speed of the circuit.

[0040] The first adjustment unit may include a first comparator and a first switch tube S1. The first input terminal of the first comparator is connected to the reference voltage terminal, the other end of the reference voltage is grounded, the second input terminal of the first comparator is connected to the series connection of the voltage-dividing resistor R3 and the voltage-dividing resistor R4, and the output terminal of the first comparator is connected to the gate of the first switch tube S1. The source of the first switch tube S1 is connected to the input voltage terminal and the inductor L1, the gate of the first switch tube S1 is connected to the output terminal of the first comparator, the source of the first switch tube S1 is connected to the drain of the second switch tube S2, the first compensation resistor R1, and one end of the second compensation capacitor C2, and then connected to the first input terminal of the pulse width comparator and the output terminal of the error amplifier.

[0041] The second adjustment unit may include a second comparator and a second switch tube S2. The first input terminal of the second comparator is connected to the reference voltage terminal, the other end of the reference voltage is grounded, the second input terminal of the second comparator is connected to the series connection of the voltage-dividing resistor R3 and the voltage-dividing resistor R4, and the output terminal of the second comparator is connected to the gate of the second switch tube S2. The drain of the second switch tube S2 is connected to the drain of the first switch tube S1, the first compensation resistor R1, and one end of the second compensation capacitor C2, and then connected to the first input terminal of the pulse width comparator and the output terminal of the error amplifier. The gate of the second switch tube S2 is connected to the output terminal of the second comparator, and the source of the second switch tube S2 is grounded.

[0042] It can be understood that in the embodiment of the present application, the first switch tube S1 is a PMOS (Positive Channel Metal Oxide Semiconductor) tube, and the second switch tube S2 is an NMOS (N-Metal-Oxide-Semiconductor) tube. In other embodiments, the first switch tube S1 can also be an NMOS tube, and the second switch tube S2 can also be a PMOS tube, which is not limited here.

[0043] In some embodiments, reference Figure 1, when the load resistance R2 suddenly increases, that is, when R2 suddenly changes from a light load to a heavy load, R2 needs more load current to meet the load requirements, which will cause the output voltage Vout to decrease. Since the first feedback voltage VFB is taken from the voltage divider network of the output voltage Vout, the decrease in the output voltage Vout will cause the first feedback voltage VFB to also decrease. At this time, the first feedback voltage VFB is compared with the first reference voltage Vref through the error amplifier. Since the first feedback voltage VFB decreases and the first reference voltage Vref remains unchanged, the first error voltage Vea will also decrease. The error amplifier outputs the first error voltage Vea to the pulse width comparator. If the first error voltage decreases to less than the first error voltage threshold, at this time, in order to alleviate the undershoot of the output voltage Vout, the first comparator in the first adjustment unit can compare the current first feedback voltage VFB with the reference voltage Vref2 to make the output of the first comparator 0 (low level), and then the gate of the first switch tube S1 is also 0; because the source of the first switch tube S1 is connected to the power supply VDD at this time, the source potential of the first switch tube S1 is higher than the gate potential, the first switch tube S1 is turned on, and then the power supply VDD charges the first compensation capacitor C1 and the second compensation capacitor C2 to increase the first error voltage Vea. In this way, the output voltage undershoot can be quickly alleviated, so that the output voltage Vout increases.

[0044] It can be understood that the first comparator controls the first switch tube S1 to be turned on by setting the output end of the first comparator connected to the gate of the first switch tube to a low level signal. In this way, the gate voltage of the first switch tube is less than the source voltage of the first switch tube, so that the first switch tube can be turned on.

[0045] Further, the first error voltage Vea is used as one of the input signals of the pulse width comparator, and after being compared with the superposition signal of the slope compensation voltage signal Vslope and the current sampling signal Vsense, a first pulse width signal can be obtained. Then, the first pulse width signal is output to the driving unit to drive the third switch tube S3 to close, and the fourth switch tube S4 is in the off state. After the third switch tube S3 is closed, the power supply VDD can flow through the inductor L1, and the inductor current IL generated on the inductor L1 gradually increases.

[0046] Based on the above, the first error voltage Vea is rapidly increased by charging the first compensation capacitor C1 and the second compensation capacitor C2, so that the pulse width comparator can quickly control the third switch tube S3 to close through the first pulse width signal, and the inductor current IL gradually increases. When the inductor current IL rises to a value greater than the load current, the output voltage Vout begins to increase and eventually stabilizes, effectively alleviating the output voltage undershoot.

[0047] It can be understood that after the pulse width comparator obtains the first error voltage, when the first error voltage decreases to less than the first error voltage threshold, the pulse width comparator outputs the first pulse width signal to turn on the third switch tube, and the inductor current IL generated on the inductor L1 gradually increases, and the load current of the load resistor decreases. After the inductor current IL is greater than the load current, the output voltage of the transient response circuit is not less than the first output voltage threshold, for example Figure 2 The first output voltage threshold Vout1 in.

[0048] The first error voltage Vea is controlled to increase rapidly by the first regulating unit, so that the undershoot output voltage Vout also increases rapidly, and the undershoot of the output voltage Vout is quickly alleviated. Figure 2 As shown in the output voltage variation diagram, it can be seen from the curve 22 that in the t1-t2 period, the output voltage Vout decreases to the minimum value Vout2 at time T1. Since the first feedback voltage VFB and the first error voltage Vea decrease as the output voltage decreases, the first error voltage Vea is increased to Vea2 by the first regulating unit. At time T1, the output voltage Vout begins to increase rapidly after decreasing to the minimum value Vout2 by the first regulating unit, and the undershoot of the output voltage is quickly alleviated.

[0049] In some embodiments, when the load resistance R2 decreases, that is, when the load resistance R2 changes from heavy load to light load, the current required by the load resistance R2 decreases due to the decrease in the load resistance R2, thereby causing the output voltage Vout to increase (overshoot). Since the first feedback voltage VFB is taken from the voltage divider network of the output voltage Vout, the increase in the output voltage Vout will cause the first feedback voltage VFB to also increase. The first feedback voltage VFB is compared with the first reference voltage Vref through the error amplifier. Since the first feedback voltage VFB increases and the first reference voltage Vref remains unchanged, the first error voltage Vea increases. The error amplifier outputs the first error voltage Vea to the pulse width comparator. If the first error voltage increases to be greater than the second error voltage threshold, at this time, in order to alleviate the overshoot of the output voltage Vout, the second comparator in the second adjustment unit can be used to compare the current first feedback voltage VFB with the reference voltage Vref3 so that the output of the second comparator is 1 (high level), and then the gate of the second switch tube S2 is also 1. Since the source of the second switch tube S2 is grounded at this time, the gate potential is higher than the source potential, and the second switch tube S2 is turned on, and then the first compensation capacitor C1 and the second compensation capacitor C2 are quickly discharged to reduce the first error voltage Vea. In this way, the output voltage overshoot can be quickly alleviated, so that the output voltage Vout is reduced.

[0050] It can be understood that the second comparator controls the conduction of the second switch tube by outputting a high-level signal at the output end of the second comparator connected to the gate of the second switch tube, and the gate voltage of the second switch tube is greater than the source voltage of the second switch tube, so that the second switch tube is turned on.

[0051] Further, the first error voltage Vea is used as one of the input signals of the pulse width comparator, and is compared with the superposition signal of the slope compensation voltage signal Vslope and the current sampling signal Vsense to obtain a second pulse width modulation signal, and is output to the driving unit to drive the fourth switch tube S4 to close. At this time, the third switch tube S3 is in the off state. After the fourth switch tube S4 is closed, the inductor L1 gradually releases the electric energy to the output capacitor C3 and the load resistors R2 and R3, and at this time, the inductor current IL on the inductor L1 gradually decreases.

[0052] Based on the above, the first error voltage Vea is rapidly reduced by rapidly discharging the first compensation capacitor C1 and the second compensation capacitor C2, so that the pulse width comparator can quickly control the fourth switch tube S4 to close through the second pulse width signal, thereby gradually reducing the inductor current IL. When the inductor current IL drops to less than the load current, the output voltage Vout begins to decrease and eventually stabilizes, effectively alleviating the output voltage overshoot.

[0053] It can be understood that after the pulse width comparator obtains the first error voltage, when the first error voltage increases, the pulse width comparator outputs the first pulse width signal to turn on the fourth switch tube, the inductor current IL generated on the inductor L1 gradually decreases, and the load current of the load resistor increases. After the inductor current IL is less than the load current, the output voltage of the transient response circuit is not greater than the second output voltage threshold, for example Figure 2 The second output voltage threshold Vout3 in.

[0054] It can be understood that the first output voltage threshold may be smaller than the second output voltage threshold.

[0055] The first error voltage Vea is rapidly reduced by the second regulating unit, so that the output voltage Vout is also rapidly reduced, and the overshoot of the output voltage Vout is rapidly alleviated. The change of the output voltage Vout can be referred to Figure 2 It can be seen from the curve 22 that in the period t3-t4, the output voltage Vout increases to a maximum value Vout4 at time T3, because the first feedback voltage VFB and the first error voltage Vea increase with the increase of the output voltage. The first error voltage Vea is increased to Vea4 by the second regulating unit. At time T3, the output voltage Vout quickly begins to decrease after increasing to the maximum value Vout4 by the second regulating unit, and the overshoot of the output voltage is quickly alleviated.

[0056] Based on the above scheme, the transient response circuit provided by the embodiment of the present application increases the first error voltage by adding a first adjustment unit in the output voltage undershoot stage, thereby quickly increasing the output voltage and quickly alleviating the undershoot of the output voltage. In the output voltage overshoot stage, a second adjustment unit is added to quickly discharge the compensation capacitor so that the first error voltage is reduced, thereby reducing the output voltage and quickly alleviating the overshoot of the output voltage. The transient response speed of the transient response circuit is fast, which improves the problem that the load transient response circuit cannot work normally due to the output voltage overshoot, thereby improving the stability of the circuit.

[0057] In contrast, in order to alleviate output voltage overshoot, in some schemes, the first error voltage of the error amplifier is used to drive C1 and C2 to charge to increase the first error voltage and thus alleviate the undershoot of the output voltage, or the first error voltage of the error amplifier is used to drive the first compensation capacitor C1 and the second compensation capacitor C2 to discharge to reduce the first error voltage Vea and thus alleviate the overshoot of the output voltage.

[0058] refer to Figure 3 In the transient response circuit 20 shown, when the load resistance R2 increases and the load resistance R2 changes from light load to heavy load, the load current required on R2 increases, causing the output voltage Vout to decrease rapidly (undershoot). Since the first feedback voltage VFB is taken from the voltage of the resistor R4 in the voltage divider network of the output voltage Vout, the decrease in the output voltage Vout will cause the first feedback voltage VFB to also decrease. Because the error amplifier can obtain the first error voltage Vea after comparing the first feedback voltage VFB with the reference voltage Vref1, and the reference voltage Vref1 is a constant value, the first error voltage Vea will decrease as the first feedback voltage VFB decreases. At this time, the change in the output voltage Vout is as follows: Figure 2 As shown, it can be seen from the curve 21 that during the period t1-t2', the output voltage Vout gradually decreases until the output voltage drops to the minimum value Vout2 at time T2. At the same time, the first feedback voltage VFB also decreases accordingly.

[0059] Further, the first feedback voltage VFB is compared with the first reference voltage Vref1 through the error amplifier, because both the first feedback voltage VFB and the first error voltage Vea are reduced. Then, the error amplifier amplifies the first error voltage Vea and outputs it to the pulse width comparator. After the pulse width comparator receives the first error voltage Vea, in order to alleviate the undershoot of the output voltage, C1 and C2 are charged through the error amplifier to increase the current first error voltage Vea, and then the current first error voltage Vea is compared with the superposition signal of the slope compensation voltage signal Vslope and the current sampling signal Vsense through the pulse width comparator to obtain the first pulse width signal, and output to the driving unit to drive the third switch tube S3 to close, at this time the fourth switch tube S4 is in the off state. It can be understood that the duty cycle of the first pulse width signal can be increased by increasing the first error voltage Vea, and the duty cycle refers to the proportion of the power-on time relative to the total time in a pulse cycle. The duty cycle can refer to the proportion of the conduction time of S3 relative to the total time. After the third switch tube S3 is closed, the power supply VDD flows through the inductor L1 and then is grounded through the third switch tube S3. The inductor current IL generated on the inductor L1 also gradually increases. When the inductor current IL increases to be greater than the load current, the output voltage Vout1 starts to rise and eventually tends to be stable. For example, in the period T2-t2′ in the figure, starting from time T2, the output voltage Vout starts to gradually increase from Vout1, thereby alleviating the undershoot of the output voltage Vout.

[0060] Continue to refer Figure 3 In the transient response circuit 20 shown, when the load resistance R2 decreases, that is, when the load resistance R2 changes from heavy load to light load, the voltage and current on R2 also decrease, causing the output voltage Vout to increase rapidly (overshoot). Since the first feedback voltage VFB is taken from the voltage of the resistor R4 in the voltage divider network of the output voltage Vout, the increase in the output voltage Vout will cause the first feedback voltage VFB to increase as well. Because the error amplifier can obtain the first error voltage Vea after comparing the first feedback voltage VFB with the reference voltage Vref1, and the reference voltage Vref1 is a constant value, the first error voltage Vea will decrease as the first feedback voltage VFB increases. At this time, the change in the output voltage Vout is as follows: Figure 2As shown, it can be seen from the curve 21 that at the moment t3-T4, the output voltage Vout gradually increases until the output voltage surges to the maximum value Vout3 at the moment T3′, and the first feedback voltage VFB and the first error voltage Vea also increase. Then, the error amplifier outputs the first error voltage Vea to the pulse width comparator. After the pulse width comparator receives the first error voltage Vea, in order to alleviate the surge of the output voltage, the error amplifier discharges C1 and C2 to reduce the current first error voltage Vea. The pulse width comparator compares the first error voltage Vea with the superposition signal of the slope compensation voltage signal Vslope and the current sampling signal Vsense to obtain a second pulse width modulation signal to output to the drive unit to drive the fourth switch tube S4 to close, and the third switch tube S3 is in the off state at this time. It can be understood that by reducing the first error voltage Vea, the duty cycle of the first pulse width signal can be reduced. The duty cycle refers to the proportion of the power-on time relative to the total time in a pulse cycle. In the embodiment of the present application, the duty cycle can refer to the proportion of the conduction time of S4 relative to the total time. After the fourth switch tube S4 is turned on, since the inductor L1 is connected to the output voltage terminal through the fourth switch tube S4, the inductor L1 gradually releases its stored electric energy to the output capacitor C3 and the load resistor R2, so that the inductor current IL gradually decreases. When the inductor current IL is less than the load current, the output voltage Vout begins to gradually decrease and eventually stabilizes. For example Figure 2 In the T3′-T4 period, starting from time T3′, the output voltage starts to gradually decrease from Vout3, thereby alleviating the overshoot of the output voltage Vout.

[0061] However, in the above scheme, when the load switches between light load and heavy load, since the compensation capacitor in the compensation unit is generally a capacitor with a large capacity of tens of pico-farads, when the load is switched from light load to heavy load in a stepwise manner, the speed of charging C1 and C2 of the compensation unit driven by the first error voltage of the error amplifier is slow, resulting in a slow adjustment of the entire transient response loop, and the output voltage is also difficult to obtain a fast transient response, so that the first error voltage Vea is still at a low level position, causing the output voltage Vout to still be in an undershoot state. Similarly, when the load is switched from heavy load to light load in a stepwise manner, the entire transient response loop is adjusted slowly, and the output voltage is also difficult to obtain a fast transient response, so that the first error voltage Vea is still at a high level position, causing the output voltage Vout to still be in an overshoot state. Therefore, only by driving C1 and C2 to charge and discharge through the first error voltage of the error amplifier to alleviate the undershoot or overshoot of the output voltage, the transient response speed of the transient response circuit 20 is lower than that of the transient response circuit 10 in the embodiment of the present application.

[0062] It can be understood that, due to the large capacity of the first compensation capacitor C1 and the second compensation capacitor C2, when the load step changes from light load to heavy load, the first error voltage Vea is still at the low level position when the load is light load, and only the first error voltage of the error amplifier is used to drive C1 and C2 to charge, which will result in a slower transient response of the output voltage. When the load step changes from light load to heavy load, the first error voltage Vea is still at the high level position when the load is heavy load, and only the first error voltage of the error amplifier is used to drive C1 and C2 to discharge, which will result in a slower transient response of the output voltage.

[0063] The following will Figure 1 The transient response circuit 10 output voltage change curve 22 and Figure 3 The transient response circuit 20 output voltage change curve 21 is compared with the reference Figure 2 , we can see that:

[0064] When the load R2 changes from light load to heavy load, since the period t1-t2 is the main period when the output voltage Vout undershoots the most, shortening the transient response time between t1-t2 can alleviate the transient response speed of the output voltage undershoot. Compared with the output voltage of curve 22, which has a transient response at time T1, that is, the output voltage begins to increase, the output voltage of curve 21 has a transient response at time T2. Because T1<T2, Figure 1 The transient response speed of the output voltage of the transient response circuit 10 shown is significantly lower than Figure 3 The transient response speed of the output voltage of the transient response circuit 20 shown in the figure also shows that charging C1 and C2 by the first regulating unit is faster in alleviating the undershoot of the output voltage Vout.

[0065] When the load R2 changes from light load to heavy load, since the period t3-t4 is the main period when the output voltage Vout surges the most, shortening the transient response time between t3-t4 can reduce the speed of the output voltage surge. Compared with curve 22, which performs a transient response at time T3, that is, the output voltage begins to decrease, curve 21 performs a transient response at time T3′, because T3<T3′, so Figure 1 The transient response speed of the output voltage of the transient response circuit 10 shown is significantly lower than Figure 3 The transient response speed of the output voltage of the transient response circuit 20 shown in the figure indicates that charging C1 and C2 by the second regulating unit is faster in reducing and alleviating the overshoot of the output voltage Vout.

[0066] In summary, through the transient response circuit provided by the embodiment of the present application, in the output voltage undershoot stage, the first adjustment unit is added to quickly charge the compensation capacitor so that the first error voltage increases, thereby increasing the output voltage and quickly alleviating the undershoot of the output voltage. In the output voltage overshoot stage, the second adjustment unit is added to quickly discharge the compensation capacitor so that the first error voltage decreases, thereby reducing the output voltage, quickly alleviating the overshoot of the output voltage, and improving the transient response speed of the transient response circuit.

[0067] It can be understood that in some other embodiments, in order to improve the transient response speed of the transient response circuit, other adjustment circuits can be connected to the output end of the error amplifier to adjust the size of the first error voltage, so that the relationship between the inductor current and the load current can be adjusted by increasing or decreasing the first error voltage, thereby quickly alleviating the overshoot or undershoot of the output voltage, which is not limited here.

[0068] The present application provides a switching converter, which may include the above-mentioned transient response circuit 10 .

[0069] The present application provides a chip, which may include the above-mentioned transient response circuit 10 .

[0070] The present application provides an electronic device, which may include the above-mentioned transient response circuit 10, switching converter or chip.

[0071] The various embodiments of the mechanism disclosed in the present application can be implemented in hardware, software, firmware or a combination of these implementation methods. The embodiments of the present application can be implemented as a computer program or program code executed on a programmable system, which includes at least one processor, a storage system (including volatile and non-volatile memory and / or storage elements), at least one input device and at least one output device.

[0072] Program code can be applied to input instructions to perform the functions described in this application and generate output information. The output information can be applied to one or more output devices in a known manner. For the purposes of this application, a processing system includes any system having a processor such as, for example, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), or a microprocessor.

[0073] Program code can be implemented with high-level programming language or object-oriented programming language to communicate with the processing system. When necessary, program code can also be implemented with assembly language or machine language. In fact, the mechanism described in this application is not limited to the scope of any specific programming language. In either case, the language can be a compiled language or an interpreted language.

[0074] In some cases, the disclosed embodiments may be implemented in hardware, firmware, software, or any combination thereof. The disclosed embodiments may also be implemented as instructions carried or stored on one or more temporary or non-temporary machine-readable (e.g., computer-readable) storage media, which may be read and executed by one or more processors. For example, instructions may be distributed over a network or through other computer-readable media. Therefore, machine-readable media may include any mechanism for storing or transmitting information in a machine (e.g., computer) readable form, including, but not limited to, floppy disks, optical disks, optical disks, read-only memories (CD-ROMs), magneto-optical disks, read-only memories (ROMs), random access memories (RAMs), erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), magnetic or optical cards, flash memory, or a tangible machine-readable memory for transmitting information (e.g., carrier waves, infrared signals, digital signals, etc.) using the Internet in electrical, optical, acoustic, or other forms of propagation signals. Therefore, machine-readable media include any type of machine-readable media suitable for storing or transmitting electronic instructions or information in a machine (e.g., computer) readable form.

[0075] In the accompanying drawings, some structural or method features may be shown in a specific arrangement and / or order. However, it should be understood that such a specific arrangement and / or order may not be required. Instead, in some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. In addition, the inclusion of structural or method features in a particular figure does not mean that such features are required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0076] It should be noted that the units / modules mentioned in the various device embodiments of the present application are all logical units / modules. Physically, a logical unit / module can be a physical unit / module, or a part of a physical unit / module, or can be implemented as a combination of multiple physical units / modules. The physical implementation method of these logical units / modules themselves is not the most important. The combination of functions implemented by these logical units / modules is the key to solving the technical problems proposed by the present application. In addition, in order to highlight the innovative part of the present application, the above-mentioned device embodiments of the present application do not introduce units / modules that are not closely related to solving the technical problems proposed by the present application, which does not mean that there are no other units / modules in the above-mentioned device embodiments.

[0077] It should be noted that in the examples and description of this patent, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "includes" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "includes one" do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0078] Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, it will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application.

Claims

1. A transient response circuit, characterized in that: The transient response circuit includes a first regulating unit, a second regulating unit and an error amplifier, wherein: The first regulating unit and the second regulating unit are both connected to the output end of the error amplifier; The first regulating unit is used for controlling the first error voltage to increase when the first error voltage output by the error amplifier is less than a first error voltage threshold; The second regulating unit is used for controlling the first error voltage to decrease when the first error voltage output by the error amplifier is greater than a second error voltage threshold; The first error voltage threshold is less than the second error voltage threshold.

2. The transient response circuit according to claim 1, characterized in that: The transient response circuit further includes a compensation unit, the first adjustment unit includes a first switch tube and a first comparator, and the first comparator is used to control the first switch tube to be turned on; The first regulating unit is used to charge the compensation unit when the first switch tube is turned on, so that the first error voltage increases to control the output voltage of the transient response circuit to be no less than a first output voltage threshold.

3. The transient response circuit according to claim 2, characterized in that: The compensation unit includes a first compensation capacitor, a second compensation capacitor and a first compensation resistor. The first end of the first switch tube is used to obtain an input voltage. The control end of the first switch tube is connected to the output end of the first comparator. The second end of the first switch tube is respectively connected to the first end of the second compensation capacitor and the first end of the first compensation resistor. The second end of the first compensation resistor is connected to the first end of the first compensation capacitor. The second end of the first compensation capacitor and the second end of the second compensation capacitor are both grounded.

4. The transient response circuit according to claim 3, characterized in that: The second regulating unit includes a second switch tube and a second comparator, and the second comparator is used to control the second switch tube to be turned on; The second regulating unit is used to discharge the compensation unit when the second switch tube is turned on, so that the first error voltage is reduced to control the output voltage of the transient response circuit to be no greater than a second output voltage threshold.

5. The transient response circuit according to claim 4, characterized in that: The first end of the second switch tube is grounded, the control end of the second switch tube is connected to the output end of the second comparator, the second end of the second switch tube is respectively connected to the first ends of the second compensation capacitor and the first compensation resistor, and the second end of the first compensation resistor is connected to the first compensation capacitor.

6. The transient response circuit according to claim 2, characterized in that: The first comparator is used to output a low-level signal, and the gate voltage of the first switch tube is less than the source voltage of the first switch tube, so that the first switch tube is turned on.

7. The transient response circuit according to claim 4, characterized in that: The second comparator is used to output a high level signal, and the gate voltage of the second switch tube is greater than the source voltage of the second switch tube, so that the second switch tube is turned on.

8. The transient response circuit according to claim 1, characterized in that: The transient response circuit further includes a pulse width comparator, a driving unit, a third switch tube and a fourth switch tube, wherein the pulse width comparator is used to control the driving unit to drive the third switch tube or the fourth switch tube to be turned on; The first input end of the pulse width comparator is respectively connected to the output end of the error amplifier, the first regulating unit and the second regulating unit, the output end of the pulse width comparator is connected to the input end of the driving unit, the first output end of the driving unit is connected to the control end of the third switch tube, the second output end of the driving unit is connected to the control end of the fourth switch tube, and the first end of the third switch tube and the first end of the fourth switch tube are respectively connected to the first end of the inductor, the second end of the inductor is connected to the input voltage end, the second end of the third switch tube is grounded, and the second end of the fourth switch tube is connected to the output voltage end; The pulse width comparator is used to obtain the first error voltage, and control the driving unit to drive the third switch tube or the fourth switch tube to turn on based on the first error voltage.

9. The transient response circuit according to claim 8, characterized in that: When the first error voltage is increased based on the control of the first adjustment unit, the pulse width comparator outputs a first pulse width signal, and the driving unit controls the third switch tube to be turned on based on the first pulse width signal, so that the output voltage of the transient response circuit is not less than a first output voltage threshold; When the first error voltage is reduced based on the control of the second adjustment unit, the pulse width comparator outputs a second pulse width signal, and the driving unit controls the fourth switch tube to be turned on based on the second pulse width signal, so that the output voltage of the transient response circuit is not greater than a second output voltage threshold.

10. A switching converter, characterized in that: include: The transient response circuit according to any one of claims 1 to 9.

11. A chip, characterized in that: The chip includes the transient response circuit according to any one of claims 1 to 9.

12. An electronic device, characterized in that: The electronic device comprises the switching converter as claimed in claim 10 and the chip as claimed in claim 11.

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