Control circuit of DC transformer, DC transformer

Abstract

The present application discloses a control circuit of a direct current transformer and a direct current transformer. When the load current of the direct current transformer suddenly changes from a smaller value to a larger value, the output voltage of the direct current transformer will drop rapidly, and the voltage of the first input terminal of the hysteresis comparator circuit and the voltage of the second input terminal of the hysteresis comparator circuit will drop along with the drop of the output voltage. However, due to the effect of the high-pass filter circuit, the voltage of the first input terminal of the hysteresis comparator circuit and the voltage of the second input terminal of the hysteresis comparator circuit drop at different rates. When the difference between the voltage of the first input terminal of the hysteresis comparator circuit and the voltage of the second input terminal of the hysteresis comparator circuit reaches the hysteresis voltage of the hysteresis comparator circuit, the output signal of the output terminal of the hysteresis comparator circuit is flipped to turn on the direct current transformer, so that the output voltage of the direct current transformer can return to the target value in time, thereby improving the output response of the direct current transformer.

Description

Technical Field

[0001] The present application relates to the technical field of direct current converters, and in particular to a control circuit of a direct current transformer and a direct current transformer. Background Art

[0002] A DC-to-DC converter, also known as a DC-DC converter or a DC transformer, is a circuit or electromechanical device for converting electrical energy. It can convert a DC power supply into a DC power supply of a different voltage.

[0003] The operating modes of the DC-DC converter include the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In addition, the operating modes of the DC-DC converter also include the constant on time mode (COT). The DC-DC converter can operate in both the DCM mode and the COT mode at the same time.

[0004] When the DC-DC converter operates in DCM mode and COT mode at the same time, when the load current suddenly changes from a small value to a large value, the output voltage will drop rapidly and then slowly rise back to the target value. When the output voltage drops too much, the output response of the DC-DC converter is poor. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a control circuit of a DC transformer, which can improve the output response of the DC transformer when the load current suddenly changes from a smaller value to a larger value.

[0006] The present application also proposes a DC transformer including the above control circuit.

[0007] In a first aspect, the present application provides a control circuit of a DC transformer, which is applied to a DC transformer. The control circuit includes:

[0008] High pass filter circuit;

[0009] A hysteresis comparison circuit, wherein a first input terminal of the hysteresis comparison circuit is used to be connected to an output terminal of the DC transformer via a high-pass filter circuit; the hysteresis comparison circuit is used to be connected to an output terminal of the DC transformer;

[0010] A logic control circuit, wherein the input end of the logic control circuit is connected to the output end of the hysteresis comparison circuit, the output end of the logic control circuit is used to be connected to the DC transformer, and the logic control circuit is used to control the conduction of the DC transformer according to the output signal of the output end of the hysteresis comparison circuit.

[0011] According to the control circuit of the DC transformer of the embodiment of the first aspect of the present application, there is at least the following beneficial effect: the control circuit of the DC transformer of the embodiment of the present application includes a high-pass filter circuit, a hysteresis comparison circuit and a logic control circuit, the first input end of the hysteresis comparison circuit is used to be connected to the output end of the DC transformer through the high-pass filter circuit; the hysteresis comparison circuit is used to be connected to the output end of the DC transformer; the input end of the logic control circuit is connected to the output end of the hysteresis comparison circuit, the output end of the logic control circuit is used to be connected to the DC transformer, and the logic control circuit is used to control the conduction of the DC transformer according to the output signal of the output end of the hysteresis comparison circuit. The control circuit of the embodiment of the present application can be applied to a DC transformer. When the load current of the DC transformer suddenly changes from a smaller value to a larger value, the output voltage of the DC transformer will drop rapidly. The voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit will drop along with the drop in the output voltage. However, due to the effect of the high-pass filter circuit, the voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit drop at different rates. When the difference between the voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit reaches a preset value, the output signal at the output terminal of the hysteresis comparator circuit flips from a low level to a high level to turn on the DC transformer, so that the output voltage of the DC transformer can return to the target value in time, thereby improving the output response of the DC transformer and avoiding excessive drop in the output voltage of the DC transformer.

[0012] According to some embodiments of the first aspect of the present application, the high-pass filter circuit includes a first capacitor and a second resistor, and the first capacitor and the second resistor are connected in series;

[0013] The hysteresis comparison circuit includes a first hysteresis comparator, and the first input end of the first hysteresis comparator serves as the first input end of the hysteresis comparison circuit; the second input end of the first hysteresis comparator serves as the second input end of the hysteresis comparison circuit, and the second input end of the first hysteresis comparator is used to be connected to the output end of the DC transformer through a first resistor; and the first capacitor is connected in parallel with the first resistor.

[0014] According to some embodiments of the first aspect of the present application, the first input terminal of the first hysteresis comparator is grounded through a second capacitor.

[0015] According to some embodiments of the first aspect of the present application, a second comparator is further included, wherein a first input terminal of the second comparator is used to access the error voltage terminal of the DC transformer, a second input terminal of the second comparator is used to access the output terminal of the DC transformer, and an output terminal of the second comparator is connected to the logic control circuit.

[0016] According to some embodiments of the first aspect of the present application, the logic control circuit includes a first AND gate, a second AND gate, a first OR gate, a first NOR gate and a second NOR gate; the first input end of the first AND gate is used to access a first indication signal, the second input end of the first AND gate is connected to the output end of the first hysteresis comparator, and the third input end of the first AND gate is used to access a DCM control signal; the first input end of the second AND gate is connected to the output end of the second comparator, the second input end of the second AND gate is used to access the first indication signal, the first input end of the first OR gate is connected to the output end of the first AND gate, the second input end of the first OR gate is connected to the output end of the second AND gate, the first input end of the first NOR gate is connected to the output end of the first OR gate, the second input end of the first NOR gate is connected to the output end of the second NOR gate, the first input end of the second NOR gate is connected to the output end of the first NOR gate, the second input end of the second NOR gate is used to access a timing signal, and the output end of the second NOR gate is connected to the DC transformer; the output end of the second NOR gate serves as the output end of the logic control circuit.

[0017] According to some embodiments of the first aspect of the present application, the hysteresis voltage of the first hysteresis comparator is 10mv.

[0018] A second aspect of the present application provides a DC transformer, including:

[0019] A control circuit for a DC transformer as described in any one of the embodiments of the first aspect of the present application.

[0020] According to some embodiments of the second aspect of the present application, the present invention further includes:

[0021] A power switch circuit is connected to the output end of the logic control circuit, and the power switch circuit is used to be turned on or off according to the output signal of the logic control circuit.

[0022] According to some embodiments of the second aspect of the present application, the power switching circuit includes a second in-phase buffer and a first power tube, the first power tube is used to periodically turn on or off according to the output signal of the logic control circuit to convert the input voltage into an output voltage; the input end of the second in-phase buffer is connected to the gate of the first power tube, and the output signal of the output end of the second in-phase buffer serves as a second indication signal.

[0023] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0025] Figure 1 A circuit diagram of a DC transformer of some embodiments of the present application;

[0026] Figure 2 for Figure 1 Partial signal timing diagram of the DC transformer;

[0027] Figure 3 A circuit diagram of a control circuit of a DC transformer of some embodiments of the first aspect of the present application;

[0028] Figure 4 For joined Figure 3 A circuit diagram of a DC transformer of a control circuit;

[0029] Figure 5 for Figure 4 Partial signal timing diagram of the DC transformer in;

[0030] Figure 6 for Figure 4 Partial signal timing diagram of the DC transformer in.

[0031] The figures are as follows:

[0032] A first hysteresis comparator COMP_HYS; a second comparator COMP; a first AND gate A1; a second AND gate A2; a first OR gate O1; a first NOR gate NO1; a second NOR gate NO2; a first indication signal HSFBN; a second indication signal HSFB; a first capacitor Cf; a second capacitor C1; a first resistor Rt; a second resistor Rf; a first in-phase buffer E1; and a second in-phase buffer E2. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0034] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0035] In the description of this application, if there is a description of first or second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0036] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0037] Reference Figure 1 , Figure 1 Figure 1 is a schematic diagram of the DC transformer circuit. Figure 1 The DC transformer shown includes a first power tube HS and a second power tube LS. When the first power tube HS is turned on, the DC transformer converts the input voltage into an output voltage. It should be noted that in the description of the present application, the DC transformer being turned on means that the first power tube HS is turned on; the DC transformer being turned off means that the first power tube HS is turned off. The PWM signal is determined by the second comparator COMP. The TON signal represents the ONTime timing output signal of the COT control mode. When the TON signal is at a high level, it indicates that the on-time timing of the first power tube HS is over, and the first power tube HS is turned off at this time. The HSFBN signal is the first indication signal HSFBN, which is the indication signal that the first power tube HS is turned on. When the HSFBN signal is at a high level, it indicates that the first power tube HS is turned off; the HSFB signal is the second indication signal HSFB. When the HSFB signal is at a high level, it indicates that the first power tube HS is turned on. The DCM control signal is used to control the DC transformer to work in DCM mode. When the DCM control signal is high, it means that the chip is in DCM mode. The first power tube HS and the second power tube LS are connected to the inductor. The signal in the node where the first power tube HS, the second power tube LS and the inductor are connected is recorded as the SW signal. The ZCD signal is the indication signal of the inductor current. When the inductor current is 0, the ZCD signal is high. Figure 2 , Figure 2The timing diagram of some signals when the load current ILOAD changes when the DC transformer works in DCM mode and COT mode at the same time. ILOAD is the load current ILOAD, PWM_COMP is the output signal of the second comparator COMP, VREF is the reference voltage of the DC transformer; VOUT is the output voltage of the DC transformer; the two input terminals of the third comparator Gm are respectively connected to the reference voltage VREF and the output voltage VOUT, and the output voltage EAO of the third comparator Gm is the error voltage, which represents the difference between the reference voltage VREF and the output voltage VOUT; Figure 2 In the figure, the horizontal axis ON time period indicates that the first power tube HS is turned on, the OFF time period indicates that the first power tube HS is turned off, and the TRI time period indicates that the first power tube HS enters a high-impedance state; the solid line indicates the situation when the load current ILOAD does not change, and the dotted line indicates the situation when the load current ILOAD changes suddenly. When the load current ILOAD does not change, such as at T0, when the output voltage VOUT = error voltage EAO, PWM_COMP flips, and the first power tube HS is turned on during the ON time period, and then the first power tube HS is turned off during the OFF time, and then in the TRI time period, the first power tube HS is in a high-impedance state; while the first power tube HS is in a high-impedance state, the load changes, such as at T1, the load current ILOAD changes suddenly from a smaller value to a larger value, and the output voltage VOUT drops rapidly, until at T2, when the output voltage VOUT is equal to the error voltage EAO, the PWM_COMP signal flips, turning on the first power tube HS again, and causing the output voltage VOUT to gradually rise to the target value. From moment T1 to moment T2, the amplitude of the output voltage drop is UnderShoot. At present, in the DC transformer of related technology, UnderShoot is too large, the output response of the DC transformer is poor, and the output voltage amplitude will be too low at certain moments. Usually, the output voltage of the DC transformer is used to power the chip. If the output voltage amplitude is too low at certain moments, the chip will be underpowered and cannot work normally.

[0038] It is understandable that, referring to Figure 2In a first aspect, an embodiment of the present application provides a control circuit of a DC transformer, characterized in that, when applied to a DC transformer, the control circuit includes a high-pass filter circuit, a hysteresis comparison circuit and a logic control circuit, wherein a first input end of the hysteresis comparison circuit is used to be connected to an output end of the DC transformer through a high-pass filter circuit; the hysteresis comparison circuit is used to be connected to an output end of the DC transformer; an input end of the logic control circuit is connected to an output end of the hysteresis comparison circuit, an output end of the logic control circuit is used to be connected to a DC transformer, and the logic control circuit is used to control the conduction of the DC transformer according to an output signal of the output end of the hysteresis comparison circuit. The control circuit of the embodiment of the present application can be applied to a DC transformer. When the load current of the DC transformer suddenly changes from a smaller value to a larger value, the output voltage of the DC transformer will drop rapidly. The voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit will drop along with the drop in the output voltage. However, due to the effect of the high-pass filter circuit, the voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit drop at different rates. When the difference between the voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit reaches a preset value, the output signal at the output terminal of the hysteresis comparator circuit flips from a low level to a high level to turn on the DC transformer, so that the output voltage of the DC transformer can return to the target value in time, thereby improving the output response of the DC transformer and avoiding excessive drop in the output voltage of the DC transformer.

[0039] It can be understood that the high-pass filter circuit includes a first capacitor Cf and a second resistor Rf, and the first capacitor Cf and the second resistor Rf are connected in series; the hysteresis comparison circuit includes a first hysteresis comparator COMP_HYS, and the first input end of the first hysteresis comparator COMP_HYS serves as the first input end of the hysteresis comparison circuit; the second input end of the first hysteresis comparator COMP_HYS serves as the second input end of the hysteresis comparison circuit; the second input end of the first hysteresis comparator COMP_HYS is connected to the output end of the DC transformer through the first resistor Rt; and the first capacitor Cf is connected in parallel with the first resistor Rt.

[0040] The control circuit of the embodiment of the present application can be applied to a DC transformer. When the load current ILOAD of the DC transformer suddenly changes from a smaller value to a larger value, the output voltage of the DC transformer will drop rapidly. The voltage at the first input terminal of the first hysteresis comparator COMP_HYS and the voltage at the second input terminal of the first hysteresis comparator COMP_HYS will drop along with the drop in the output voltage. However, due to the effect of the high-pass filter circuit, the voltage at the first input terminal of the first hysteresis comparator COMP_HYS and the voltage at the second input terminal of the first hysteresis comparator COMP_HYS drop at different rates. When the difference between the voltage at the first input terminal of the first hysteresis comparator COMP_HYS and the voltage at the second input terminal of the first hysteresis comparator COMP_HYS reaches the hysteresis voltage of the first hysteresis comparator COMP_HYS, the output signal at the output terminal of the first hysteresis comparator COMP_HYS flips from a low level to a high level, so that the DC transformer is turned on, that is, the first power tube HS of the DC transformer is turned on, so that the output voltage of the DC transformer can return to the target value in time, thereby improving the output response of the DC transformer and avoiding excessive drop in the output voltage of the DC transformer.

[0041] It can be understood that the first input terminal of the first hysteresis comparator COMP_HYS is grounded through the second capacitor C1.

[0042] It can be understood that when the first input terminal of the first hysteresis comparator COMP_HYS is a non-inverting input terminal, the second input terminal of the first hysteresis comparator COMP_HYS is an inverting input terminal; when the first input terminal of the first hysteresis comparator COMP_HYS is an inverting input terminal, the second input terminal of the first hysteresis comparator COMP_HYS is a non-inverting input terminal.

[0043] It can be understood that the control circuit also includes a second comparator COMP, a first input end of the second comparator COMP is used to access the error voltage end of the DC transformer, a second input end of the second comparator COMP is used to access the output end of the DC transformer, and an output end of the second comparator COMP is connected to the logic control circuit.

[0044] It can be understood that when the first input terminal of the second comparator COMP is the non-inverting input terminal, the second input terminal of the second comparator COMP is the inverting input terminal; when the first input terminal of the second comparator COMP is the inverting input terminal, the second input terminal of the second comparator COMP is the non-inverting input terminal.

[0045] It can be understood that the logic control circuit includes a first AND gate A1, a second AND gate A2, a first OR gate O1, a first NOR gate NO1 and a second NOR gate NO2; the first input end of the first AND gate A1 is used to access the first indication signal HSFBN, the second input end of the first AND gate A1 is connected to the output end of the first hysteresis comparator COMP_HYS, and the third input end of the first AND gate A1 is used to access the DCM control signal; the first input end of the second AND gate A2 is connected to the output end of the second comparator COMP, the second input end of the second AND gate A2 is used to access the first indication signal HSFBN, the first input end of the first OR gate O1 is connected to the output end of the first AND gate A 1, the second input end of the first OR gate O1 is connected to the output end of the second AND gate A2, the first input end of the first NOR gate NO1 is connected to the output end of the first OR gate O1, the second input end of the first NOR gate NO1 is connected to the output end of the second NOR gate NO2, the first input end of the second NOR gate NO2 is connected to the output end of the first NOR gate NO1, the second input end of the second NOR gate NO2 is used to access the timing signal, and the output end of the second NOR gate NO2 is connected to the DC transformer; when the DC transformer is turned on, the first indication signal HSFBN is at a high level; the output end of the second NOR gate NO2 serves as the output end of the logic control circuit.

[0046] It can be understood that the hysteresis voltage of the first hysteresis comparator COMP_HYS is 10mv.

[0047] Reference Figure 4 The second aspect of the present application provides a DC transformer, including:

[0048] Such as the control circuit of the DC transformer in the first aspect of the embodiment of the present application.

[0049] It can be understood that the DC transformer also includes a power switching circuit, which is connected to the output end of the logic control circuit. The power switching circuit is used to periodically turn on or off according to the output signal of the logic control circuit to convert the input voltage into the output voltage.

[0050] It can be understood that the power switch circuit includes a second in-phase buffer E2 and a first power tube HS, the first power tube HS is used to periodically turn on or off according to the output signal of the logic control circuit to convert the input voltage into an output voltage; the input end of the second in-phase buffer E2 is connected to the gate of the first power tube HS, and the output signal of the output end of the second in-phase buffer E2 is used as the second indication signal HSFB, and the second indication signal HSFB is inverted with the first indication signal HSFBN.

[0051] Refer to the following Figures 3 to 6, the working principle of the DC transformer according to the second aspect of the present application is described in detail with a specific embodiment. It is worth noting that the following description is only an exemplary description and is not a specific limitation of the present application.

[0052] The non-inverting input terminal of the third comparator Gm is connected to the reference voltage VREF, the inverting input terminal of the third comparator Gm is connected to the output voltage VOUT of the DC transformer, the output terminal of the third comparator Gm is connected to the non-inverting input terminal of the second comparator COMP, and a second filtering circuit is also connected between the output terminal of the third comparator Gm and the non-inverting input terminal of the second comparator COMP. The second filtering circuit includes a third capacitor Co, a fourth capacitor Cp, and a third resistor Rz. The third capacitor Co and the third resistor Rz are connected in series between the output terminal of the third comparator Gm and the ground terminal, and one end of the fourth capacitor is connected to the output terminal of the third comparator Gm, and the other end of the fourth capacitor is grounded. The inverting input terminal of the third comparatively strong COMP is connected to the output voltage VOUT of the DC transformer, and the non-inverting input terminal of the first hysteresis comparator COMP_HYS is connected to the output terminal of the DC transformer through a high-pass filter circuit; the inverting input terminal of the first hysteresis comparator COMP_HYS is used to connect to the output terminal of the DC transformer through a first resistor Rt; the high-pass filter circuit includes a first capacitor Cf, and the first capacitor Cf is connected in parallel with the first resistor Rt; the input terminal of the logic control circuit is connected to the output terminal of the first hysteresis comparator COMP_HYS, and the output terminal of the logic control circuit is used to connect to the DC transformer, and the high-pass filter circuit also includes a second resistor Rf, one end of the second resistor Rf is connected to the first input terminal of the first hysteresis comparator COMP_HYS, and the other end of the second resistor Rf is used to connect to the output terminal of the DC transformer through the first capacitor Cf. The non-inverting input terminal of the first hysteresis comparator COMP_HYS is grounded through the second capacitor C1. The logic control circuit includes a first AND gate A1, a second AND gate A2, a first OR gate O1, a first NOR gate NO1 and a second NOR gate NO2; the first input end of the first AND gate A1 is used to access the first indication signal HSFBN, the second input end of the first AND gate A1 is connected to the output end of the first hysteresis comparator COMP_HYS, and the third input end of the first AND gate A1 is used to access the DCM control signal; the first input end of the second AND gate A2 is connected to the output end of the second comparator COMP, the second input end of the second AND gate A2 is used to access the first indication signal HSFBN, the first input end of the first OR gate O1 ... The input end is connected to the output end of the first AND gate A1, the second input end of the first OR gate O1 is connected to the output end of the second AND gate A2, the first input end of the first NOR gate NO1 is connected to the output end of the first OR gate O1, the second input end of the first NOR gate NO1 is connected to the output end of the second NOR gate NO2, the first input end of the second NOR gate NO2 is connected to the output end of the first NOR gate NO1, the second input end of the second NOR gate NO2 is used to access the timing signal, and the output end of the second NOR gate NO2 is connected to the DC transformer; the output end of the second NOR gate NO2 serves as the output end of the logic control circuit.

[0053] The DC transformer also includes a power switching circuit, wherein an input end of the first in-phase buffer E1E1 is connected to an output end of the second NOR gate NO2, an input end of the first NOR gate N1 is connected to an output end of the first in-phase buffer E1E1, an input end of the second NOR gate N2 is connected to an output end of the first NOR gate N1, an output end of the second NOR gate N2 is connected to a gate of the first power tube HS, an input end of the second in-phase buffer E2 is connected to a gate of the first power tube HS, an output signal of an output end of the second in-phase buffer E2 is used as a second indication signal HSFB, an input end of the third NOR gate N3 is connected to an output end of the second buffer, an output signal of the third NOR gate N3 is used as a first indication signal HSFBN, and the second indication signal HSFB is inverted with the first indication signal HSFBN. The first input terminal of the third NOR gate NO3 is connected to the second indication signal HSFB, the second input terminal of the third NOR gate NO3 is connected to the first input terminal of the fourth NOR gate NO4, the second input terminal of the fourth NOR gate NO4 is connected to the ZCD signal, the output signal of the third NOR gate NO3 is used as the TRI signal, the output terminal of the third NOR gate NO3 is connected to the input terminal of the fifth NOR gate N5, the output terminal of the fifth NOR gate N5 is connected to the second input terminal of the third AND gate A3; the output terminal of the second NOR gate NO2 is connected to the input terminal of the fourth NOR gate N4, the fourth NOR gate N4 is connected to the input terminal of the fourth NOR gate N4. The output end of is connected to the first input end of the third AND gate A3, the output end of the third AND gate A3 is connected to the gate of the second power tube LS, the source of the second power tube LS is grounded, the drain of the second power tube LS is connected to the source of the first power tube HS, the drain of the first power tube HS is connected to the input voltage Vin, one end of the inductor L is connected between the source of the first power tube HS and the drain of the second power tube LS, the other end of the inductor L is grounded through the load resistor Rload, and the load resistor Rload is connected in parallel with the branch formed by the resistor Resr and the capacitor CL connected in series. The hysteresis voltage of the first hysteresis comparator COMP_HYS is 10mv.

[0054] exist Figure 4In the COT control mode, the TON signal represents the ON Time timing output signal. When the TON signal is at a high level, it indicates that the on time timing of the first power tube HS is over, and the first power tube HS is turned off. The HSFBN signal is the first indication signal HSFBN. When the first indication signal HSFBN is at a high level, it indicates that the first power tube HS is turned off; the HSFB signal is the second indication signal HSFB. When the second indication signal HSFB is at a high level, it indicates that the first power tube HS is turned on. The DCM control signal is used to control the DC transformer to operate in the DCM mode. When the DCM control signal is at a high level, it indicates that the chip is in the DCM mode. The first power tube HS and the second power tube LS are connected to an inductor, and the signal in the node where the first power tube HS, the second power tube LS, and the inductor are connected is recorded as a SW signal; the ZCD signal is an indication signal of the inductor current. When the inductor current is 0, the ZCD signal is at a high level. In the Figure 5 and Figure 6 In the figure, the ON time period of the horizontal axis indicates that the first power tube HS is in the on state, the OFF time period indicates that the first power tube HS is in the off state, and the TRI time period indicates that the first power tube HS is in the high impedance state; Figure 5 and Figure 6 In each curve in , the solid line represents the situation when the load current ILOAD does not change suddenly, and the dotted line represents the situation when the load current ILOAD changes suddenly from a smaller value to a higher value. VFBP is the voltage at the positive input terminal of the first hysteresis comparator COMP_HYS, and VFBN is the voltage at the negative input terminal of the first hysteresis comparator COMP_HYS. PWM_COMP is the output signal of the second comparator COMP, VREF is the reference voltage of the DC transformer; VOUT is the output voltage of the DC transformer; the two input terminals of the third comparator Gm are respectively connected to the reference voltage VREF and the output voltage VOUT, and the output voltage EAO of the third comparator Gm is the error voltage, which represents the difference between the reference voltage VREF and the output voltage VOUT; PWM_FAST is the output signal of the first hysteresis comparator COMP_HYS; when the load current ILOAD does not change, such as at T0, when the output voltage VOUT = error voltage EAO, PWM_COMP flips, and the first power tube HS is turned on during the ON time period, and then the first power tube HS is turned off during the OFF time period, and then the first power tube HS is in a high impedance state during the TRI time period; while the first power tube HS is in a high impedance state, the load changes, refer to Figure 6For example, at time T1, the load current ILOAD changes from a small value to a large value, the output voltage VOUT drops rapidly, and VFBP and VFBN drop with the output voltage VOUT. Due to the effect of the high-pass filter circuit, when the rate of decrease of the output voltage VOUT is greater than the cut-off frequency of the high-pass filter circuit, the rate of decrease of VFBP is slower than that of VFBN. Therefore, the difference between VFBP and VFBN will gradually increase. At time T2, when the difference between VFBP and VFBN reaches the hysteresis voltage of 10mv, the output signal PWM_FAST of the first hysteresis comparator COMP_HYS flips from a low level to a high level, turning on the first power tube HS again, so that the output voltage VOUT gradually rises to the target value. Figure 5 and Figure 6 At time T2, the output voltage VOUT is greater than the error voltage EAO, and the amplitude of the output voltage VOUT drop is UnderShoot. UnderShoot is small, thereby improving the output response of the DC transformer and avoiding excessive drop in the output voltage of the DC transformer.

[0055] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A control circuit of a DC transformer, characterized in that: Applied to a DC transformer, the control circuit comprises: High pass filter circuit; A hysteresis comparison circuit, wherein a first input terminal of the hysteresis comparison circuit is used to be connected to an output terminal of the DC transformer via a high-pass filter circuit; the hysteresis comparison circuit is used to be connected to an output terminal of the DC transformer; a logic control circuit, wherein the input end of the logic control circuit is connected to the output end of the hysteresis comparison circuit, the output end of the logic control circuit is used to be connected to the DC transformer, and the logic control circuit is used to control the conduction of the DC transformer according to the output signal of the output end of the hysteresis comparison circuit; The high-pass filter circuit comprises a first capacitor and a second resistor, wherein the first capacitor and the second resistor are connected in series; The hysteresis comparison circuit comprises a first hysteresis comparator, wherein the first input end of the first hysteresis comparator serves as the first input end of the hysteresis comparison circuit; the second input end of the first hysteresis comparator serves as the second input end of the hysteresis comparison circuit, wherein the second input end of the first hysteresis comparator is used to be connected to the output end of the DC transformer through a first resistor; and the first capacitor is connected in parallel with the first resistor; It also includes a second comparator, wherein a first input end of the second comparator is used to connect to the error voltage end of the DC transformer, a second input end of the second comparator is used to connect to the output end of the DC transformer, and an output end of the second comparator is connected to the logic control circuit; The logic control circuit includes a first AND gate, a second AND gate, a first OR gate, a first NOR gate and a second NOR gate; the first input end of the first AND gate is used to access a first indication signal, the second input end of the first AND gate is connected to the output end of the first hysteresis comparator, and the third input end of the first AND gate is used to access a DCM control signal; the first input end of the second AND gate is connected to the output end of the second comparator, the second input end of the second AND gate is used to access the first indication signal, the first input end of the first OR gate is connected to the output end of the first AND gate, the second input end of the first OR gate is connected to the output end of the second AND gate, the first input end of the first NOR gate is connected to the output end of the first OR gate, the second input end of the first NOR gate is connected to the output end of the second NOR gate, the first input end of the second NOR gate is connected to the output end of the first NOR gate, the second input end of the second NOR gate is used to access a timing signal, and the output end of the second NOR gate is connected to the DC transformer; the output end of the second NOR gate serves as the output end of the logic control circuit; The voltage at the first input terminal of the hysteresis comparator circuit and the voltage at the second input terminal of the hysteresis comparator circuit drop at different rates.

2. The control circuit of the DC transformer according to claim 1, characterized in that: The first input terminal of the first hysteresis comparator is grounded through a second capacitor.

3. The control circuit of the DC transformer according to claim 1, characterized in that: The hysteresis voltage of the first hysteresis comparator is 10mv.

4. A DC transformer, characterized in that: include: A control circuit for a DC transformer as claimed in any one of claims 1 to 3.

5. The DC transformer according to claim 4, characterized in that: Also includes: A power switch circuit is connected to the output end of the logic control circuit, and the power switch circuit is used to be turned on or off according to the output signal of the logic control circuit.

6. The DC transformer according to claim 5, characterized in that: The power switching circuit includes a second in-phase buffer and a first power tube, wherein the first power tube is used to periodically turn on or off according to the output signal of the logic control circuit to convert the input voltage into an output voltage; the input end of the second in-phase buffer is connected to the gate of the first power tube, and the output signal of the output end of the second in-phase buffer serves as a second indication signal.

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