Constant voltage control circuit, constant voltage control method thereof and constant voltage driver

Abstract

The invention provides a constant voltage control circuit, a constant voltage control method thereof and a constant voltage driver. The constant voltage control circuit comprises a reference voltage generation circuit, a threshold value generation circuit and a dynamic response control circuit. The reference voltage generation circuit is used for generating a reference voltage according to the soft start enable signal. The input end of the threshold value generation circuit is coupled to the reference voltage generation circuit, the threshold value generation circuit is used for generating a first threshold value signal based on the reference voltage, and the difference value between the reference voltage and the first threshold value signal is larger than the difference value between the reference voltage and the first threshold value signal in the steady-state working state in at least part of time of the soft start stage. The input end of the dynamic response control circuit is coupled with the threshold value generation circuit, and the dynamic response control circuit is used for triggering rapid dynamic response when the sampling signal is smaller than the first threshold value signal. According to the constant-voltage control circuit, the constant-voltage control method thereof and the constant-voltage driver, the problems of noise suppression and output voltage overshoot in the starting process can be effectively solved at the same time.

Description

Technical Field

[0001] The invention belongs to the field of power electronics, and relates to a constant voltage control technology, in particular to a constant voltage control circuit and a constant voltage control method and a constant voltage driver. Background Art

[0002] The key technical indicator of the constant voltage control circuit is the fast dynamic response capability of the constant voltage control circuit when the load changes. It is required that when the load changes, the transient change in the output voltage amplitude should be as small as possible. The constant voltage control circuit will encounter relevant technical contradictions during the startup process. In order to ensure the stability of the loop during steady-state operation, the loop gain of the constant voltage control circuit is generally designed to be small. When the load changes, the loop control response to the output voltage is slow. Therefore, it is necessary to add a fast dynamic response circuit. When the output voltage drop amplitude exceeds a certain threshold, either increase the loop gain of the control circuit, or directly open the loop control to achieve the effect of quickly adjusting the output voltage. For example Figure 1 , the threshold is obtained by reducing Δ on the basis of the reference voltage value, and the value of Δ is the maximum drop amplitude allowed for the output voltage. When the sampling signal exceeds the threshold, the constant voltage control circuit increases the loop gain, and the sampling signal corresponds to the output voltage. When the sampling signal is not lower than the threshold, there is no need to increase the loop gain of the control circuit. Triggering the fast response function will cause a certain amount of power noise.

[0003] like Figure 2 When the constant voltage driver is turned on, in order to ensure a smooth startup process and suppress overshoot, a soft start function is usually added, that is, the constant voltage driver control reference voltage slowly rises to the reference voltage value during steady-state control after startup, and the fast dynamic response threshold also slowly rises with the reference voltage. However, if the load is very heavy under extreme conditions during startup, combined with Figure 3 , the solid line is the reference voltage, the thick dotted line is the sampling signal, the output voltage rises much slower than the reference voltage. If the undervoltage fast response function is not added to the constant voltage control circuit, the output voltage overshoot is likely to occur in the closed-loop control. If the undervoltage fast response function is added to the constant voltage control circuit (that is, combined with the realization of threshold control fast response), combined Figure 4 , which can ensure that there is no overshoot, but the undervoltage quick response action will be frequently triggered during the normal startup process, resulting in power noise and affecting the smoothness of the startup. Therefore, the existing solution cannot solve the problem of normal smooth startup and output voltage overshoot under heavy load during the soft start process.

[0004] In view of this, it is necessary to provide a new structure or control method to solve at least part of the above problems. Summary of the invention

[0005] In view of one or more problems in the prior art, the present invention provides a constant voltage control circuit and a constant voltage control method thereof and a constant voltage driver.

[0006] According to one aspect of the present invention, a constant voltage control circuit is disclosed, and the constant voltage control circuit comprises:

[0007] A reference voltage generating circuit is used to generate a reference voltage according to a soft start enable signal, and in the soft start stage, the reference voltage gradually increases from an initial voltage to a preset voltage;

[0008] a threshold generation circuit, whose input terminal is coupled to the output terminal of the reference voltage generation circuit, for generating a first threshold signal based on the reference voltage, wherein the difference between the reference voltage and the first threshold signal during at least a portion of the soft start phase is greater than the difference between the reference voltage and the first threshold signal during a steady-state operation state; and

[0009] The dynamic response control circuit has an input terminal coupled to the output terminal of the threshold generation circuit and is used to trigger a fast dynamic response when a sampling signal representing the output voltage of the constant voltage driver is less than a first threshold signal.

[0010] In one embodiment, the difference between the reference voltage and the first threshold signal in the steady-state working state is a preset value. During at least part of the soft start phase, the difference between the reference voltage and the first threshold signal is n times the preset value, where n>1.

[0011] In one embodiment, within a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal gradually decreases from n times the preset value to the preset value.

[0012] In one embodiment, after a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal is a preset value.

[0013] In one embodiment, the value of n is such that a fast dynamic response is not triggered during a soft start phase under a preset load, and a fast dynamic response can be triggered during a soft start phase under a heavy load.

[0014] In one embodiment, after the soft start ends, the reference voltage is a preset voltage.

[0015] In one embodiment, the dynamic response control circuit includes a first comparison circuit, a first input terminal of the first comparison circuit is coupled to a threshold generation circuit to receive a first threshold signal, a second input terminal of the first comparison circuit receives a sampling signal, and an output terminal of the first comparison circuit outputs an undervoltage fast dynamic response control signal.

[0016] According to another aspect of the present invention, a constant voltage driver is disclosed. The constant voltage driver comprises a constant voltage control circuit as described in any one of the above items. The constant voltage control circuit is used to control the output voltage of the constant voltage driver.

[0017] According to another aspect of the present invention, a constant voltage control method is disclosed. The constant voltage control method is used to control the output voltage of a constant voltage driver. The constant voltage control method includes:

[0018] Generate a reference voltage according to a soft start enable signal, and during the soft start phase, the reference voltage gradually increases from an initial voltage to a preset voltage;

[0019] Generate a first threshold signal based on a reference voltage, wherein a difference between the reference voltage and the first threshold signal during at least a portion of the soft start phase is greater than a difference between the reference voltage and the first threshold signal during a steady-state operation state; and

[0020] The triggering of the fast dynamic response is controlled according to the first threshold signal and the sampling signal representing the output voltage of the constant voltage driver. When the sampling signal is less than the first threshold signal, the fast dynamic response is triggered.

[0021] In one embodiment, the difference between the reference voltage and the first threshold signal in the steady-state working state is a preset value. During at least part of the soft start phase, the difference between the reference voltage and the first threshold signal is n times the preset value, where n>1.

[0022] In one embodiment, within a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal gradually decreases from n times the preset value to the preset value.

[0023] In one embodiment, after a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal is a preset value.

[0024] In one embodiment, the value of n is such that a fast dynamic response is not triggered during a soft start phase under a preset load, and a fast dynamic response can be triggered during a soft start phase under a heavy load.

[0025] The present invention proposes a constant voltage control circuit, a constant voltage control method and a constant voltage driver. The constant voltage control circuit includes a reference voltage generation circuit, a threshold generation circuit and a dynamic response control circuit. The reference voltage generation circuit is used to generate a reference voltage according to a soft start enable signal. In the soft start stage, the reference voltage gradually increases from an initial voltage to a preset voltage. The input end of the threshold generation circuit is coupled to the output end of the reference voltage generation circuit, and the threshold generation circuit is used to generate a first threshold signal based on the reference voltage. During at least part of the time in the soft start stage, the difference between the reference voltage and the first threshold signal is greater than the difference between the reference voltage and the first threshold signal in a steady-state working state. The input end of the dynamic response control circuit is coupled to the output end of the threshold generation circuit, and the dynamic response control circuit is used to trigger a fast dynamic response when a sampling signal characterizing the output voltage of the constant voltage driver is less than the first threshold signal. The constant voltage control circuit, the constant voltage control method and the constant voltage driver proposed by the present invention can effectively take into account the noise suppression and output voltage overshoot problems in the startup process. The present invention can ensure that there is no power noise in the startup process, realize smooth startup, and appropriately sacrifice noise suppression performance in the case of extreme overload to ensure that there is no output voltage overshoot. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the description to explain the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 A signal waveform diagram of a constant voltage driver in the prior art is shown;

[0028] Figure 2 Another conventional constant voltage driver signal waveform diagram is shown;

[0029] Figure 3 A signal waveform diagram of another constant voltage driver in the prior art is shown;

[0030] Figure 4 A signal waveform diagram of a constant voltage driver in the prior art is shown;

[0031] Figure 5 A circuit structure schematic diagram of a constant voltage control circuit according to an embodiment of the present invention is shown;

[0032] Figure 6 A schematic diagram of signal waveforms of a constant voltage control circuit according to an embodiment of the present invention is shown;

[0033] Figure 7 FIG. 4 is a schematic diagram showing signal waveforms of a constant voltage control circuit according to another embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0035] The description in this section is only for several typical embodiments, and the present invention is not limited to the scope of the embodiments. The combination of different embodiments, the mutual replacement of some technical features in different embodiments, and the mutual replacement of the same or similar prior art means with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0036] "Coupled" or "connected" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or a connection through an intermediate circuit or component described in the embodiments in the specification; an indirect connection may also include a connection through other active or passive devices on the basis of achieving the same or similar functions, such as a connection through circuits or components such as switches, signal amplification circuits, and follower circuits. "Multiple" or "many" means two or more. In addition, in the present invention, words such as first and second are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship or order between these technical features.

[0037] An embodiment of the present invention discloses a constant voltage control circuit, which includes a reference voltage generation circuit, a threshold generation circuit and a dynamic response control circuit. The reference voltage generation circuit is used to generate a reference voltage according to a soft start enable signal. In the soft start stage, the reference voltage gradually increases from an initial voltage to a preset voltage. The process of gradually increasing from the initial voltage to the preset voltage can be a linear increase or a curve increase, which can be set according to the specific circuit and requirements. After the soft start is completed, the reference voltage is maintained at the preset voltage. The input end of the threshold generation circuit is coupled to the output end of the reference voltage generation circuit, and the threshold generation circuit is used to generate a first threshold signal based on the reference voltage. For example, the first threshold signal is obtained after the operation circuit performs operation processing on the basis of the reference voltage. In a specific embodiment, the first threshold signal is obtained by subtracting a certain signal from the reference voltage. The difference between the reference voltage and the first threshold signal during at least part of the time in the soft start stage is greater than the difference between the reference voltage and the first threshold signal in a steady-state working state. In one embodiment, the threshold generation circuit controls the difference between the reference voltage and the first threshold signal in a certain time period in the soft start stage to be greater than the difference between the reference voltage and the first threshold signal in a steady-state working state. In another embodiment, the threshold generation circuit controls the difference between the reference voltage and the first threshold signal in the soft start phase to be greater than the difference between the reference voltage and the first threshold signal in the steady-state working state. The reference voltage is greater than the first threshold signal, and the size comparison specifically corresponds to the reference voltage and the first threshold signal at the same time. The input end of the dynamic response control circuit is coupled to the output end of the threshold generation circuit, and the dynamic response control circuit controls the triggering of the fast dynamic response according to the first threshold signal and the sampling signal characterizing the output voltage of the constant voltage driver. In one embodiment, the sampling signal is positively correlated with the output voltage. In another embodiment, the sampling signal is proportional to the output voltage. When the sampling signal is less than the first threshold signal, the dynamic response control circuit triggers a fast dynamic response.

[0038] In one embodiment, the constant voltage control circuit further includes a fast dynamic response circuit, and the input end of the fast dynamic response circuit is coupled to the output end of the dynamic response control circuit. The first threshold signal is an undervoltage fast dynamic response threshold. The dynamic response control circuit outputs a fast dynamic response control signal. When the sampling signal is less than the undervoltage fast dynamic response threshold, the fast dynamic response control signal is at a first level (e.g., a high level), and the constant voltage control circuit triggers a fast dynamic response. The fast dynamic response circuit controls the loop gain of the control circuit that adjusts the output voltage according to the dynamic response control signal.

[0039] In one embodiment, if Figure 5As shown, the constant voltage control circuit includes a reference voltage generating circuit 10, a threshold generating circuit 20 and a dynamic response control circuit 30. The input end of the reference voltage generating circuit is respectively coupled to the soft start enable signal and the preset voltage Vref. The reference voltage generating circuit 10 is used to generate a reference voltage Vref_SS according to the soft start enable signal. Figure 6 In the soft start phase, the reference voltage Vref_SS increases linearly from the initial voltage to the preset voltage Vref. After the soft start ends, the reference voltage Vref_SS maintains the preset voltage Vref. The input end of the threshold generation circuit 20 is respectively coupled to the output end of the reference voltage generation circuit 10 and the soft start enable signal, and the threshold generation circuit 20 is used to generate a first threshold signal based on the reference voltage Vref_SS. The first threshold signal is an undervoltage fast dynamic response threshold.

[0040] In one embodiment, the threshold generation circuit 20 includes an operation circuit (not shown in the figure), the first input terminal of the operation circuit receives the reference voltage Vref_SS, and the second input terminal of the operation circuit receives the preset value Δ. The operation circuit obtains a first threshold signal based on the reference voltage Vref_SS and the preset value Δ, and the first threshold signal is equal to the difference between the reference voltage Vref_SS and n times the preset value Δ, where n>1. In another embodiment, in combination with Figure 6 and Figure 7 , Figure 6 The signals when the constant voltage driver is connected to the preset load (i.e. non-heavy load state) are Figure 7 are the signals when the constant voltage driver is under heavy load. Among them, the solid line is the reference voltage, the thin dotted line below the solid line is the undervoltage fast dynamic response threshold, and the thick dotted line near the solid line is the sampling signal that characterizes the output voltage of the constant voltage driver. An undervoltage fast dynamic response is added during the soft start process. The undervoltage fast dynamic response threshold of the soft start process is lower than the undervoltage fast dynamic response threshold in the steady-state working state, and the undervoltage fast dynamic response threshold of the soft start process can rise slowly and synchronously with the reference voltage in the soft start phase. The steady-state working state is the state when the constant voltage driver stably outputs constant voltage. There is also a transition phase between the soft start phase and the steady-state working state phase. The transition phase is a preset time period after the end of the soft start, for example Figure 6The area where the circled area is located. When the soft start is over, if the undervoltage fast dynamic response threshold immediately switches back to the reference voltage -Δ, it may still cause the fast response function to be falsely triggered. In one embodiment, within a preset time after the soft start is over, the difference between the reference voltage and the first threshold signal gradually decreases from n times the preset value to the preset value. When the soft start is over, the undervoltage fast dynamic response threshold slowly changes back to the undervoltage fast dynamic response threshold in the steady-state working state, thereby avoiding false triggering of the fast dynamic response after the soft start is over. By selecting the value of n, the fast dynamic response is not triggered in the soft start stage at a preset load, and the fast dynamic response can be triggered in the soft start stage at a heavy load, thereby obtaining a better optimized control effect between noise suppression and overshoot control.

[0041] In another embodiment, if Figure 6 As shown, after a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal is a preset value.

[0042] like Figure 5 , the dynamic response control circuit 30 includes a first comparison circuit, and the first comparison circuit includes a first comparator 301. The non-inverting input terminal of the first comparator 301 is coupled to the output terminal of the threshold generation circuit 20 to receive a first threshold signal, and the first threshold signal is an undervoltage fast dynamic response threshold. The inverting input terminal of the first comparator 301 receives a sampling signal, and the output terminal of the first comparator 301 outputs an undervoltage fast dynamic response control signal. The fast dynamic response control signal includes an undervoltage fast dynamic response control signal. The constant voltage control circuit adjusts the loop gain of the control circuit according to the fast dynamic response control signal. In one embodiment, when the undervoltage fast dynamic response control signal is in a first state (for example, a high level), a fast dynamic response is triggered, and the constant voltage control circuit controls to increase the loop gain or perform open-loop control.

[0043] Another embodiment of the present invention further discloses a constant voltage driver, the constant voltage driver comprising a constant voltage control circuit as described in any one of the above items, the constant voltage control circuit being used to control the output voltage of the constant voltage driver. The constant voltage driver proposed by the present invention can ensure that there is no power noise during the startup process, achieve smooth startup, and appropriately sacrifice noise suppression performance in the case of extreme heavy loads to ensure that the output voltage of the constant voltage driver does not overshoot.

[0044] Another embodiment of the present invention further discloses a constant voltage control method, which is used to control the output voltage of a constant voltage driver. The constant voltage control method includes:

[0045] Generate a reference voltage according to a soft start enable signal, and during the soft start phase, the reference voltage gradually increases from an initial voltage to a preset voltage;

[0046] Generate a first threshold signal based on a reference voltage, wherein a difference between the reference voltage and the first threshold signal during at least a portion of the soft start phase is greater than a difference between the reference voltage and the first threshold signal during a steady-state operation state; and

[0047] The triggering of the fast dynamic response is controlled according to the first threshold signal and the sampling signal representing the output voltage of the constant voltage driver. When the sampling signal is less than the first threshold signal, the fast dynamic response is triggered.

[0048] In one embodiment, a constant voltage control method is used to control a constant voltage control circuit, and the constant voltage control circuit includes a reference voltage generating circuit, a threshold generating circuit, and a dynamic response control circuit. The reference voltage generating circuit generates a reference voltage according to a soft start enable signal, and in the soft start phase, the reference voltage gradually increases from an initial voltage to a preset voltage. The threshold generating circuit generates a first threshold signal based on the reference voltage, and the difference between the reference voltage and the first threshold signal is greater than the difference between the reference voltage and the first threshold signal in a steady-state working state during at least part of the time in the soft start phase. The dynamic response control circuit controls whether to trigger a fast dynamic response according to the first threshold signal and a sampling signal characterizing the output voltage of the constant voltage driver, and triggers a fast dynamic response when the sampling signal is less than the first threshold signal.

[0049] In one embodiment, the difference between the reference voltage and the first threshold signal in the steady-state working state is a preset value. In the soft start stage, the difference between the reference voltage and the first threshold signal is n times the preset value, n>1. The threshold generation circuit is based on the reference voltage, and in the steady-state working state, the reference voltage is subtracted from the preset value to obtain the first threshold signal. In the soft start stage, the threshold generation circuit subtracts n times the preset value from the reference voltage to obtain the first threshold signal. In the transition stage between the soft start stage and the steady-state working state stage (i.e., within the preset time after the end of the soft start), the difference between the reference voltage and the first threshold signal gradually decreases from n times the preset value to the preset value, which can avoid false triggering of a fast dynamic response after the end of the soft start. In one embodiment, after the preset time after the end of the soft start, the difference between the reference voltage and the first threshold signal is a preset value.

[0050] In one embodiment, the value of n is such that a fast dynamic response is not triggered during a soft start phase under a preset load, and a fast dynamic response can be triggered during a soft start phase under a heavy load.

[0051] Those skilled in the art should know that the logic controls such as "high level" and "low level", "set" and "reset", "AND gate" and "OR gate", "non-inverting input terminal" and "inverting input terminal" in the logic controls involved in the specification or drawings can be interchanged or changed with each other, and the same function or purpose as the above embodiment can be achieved by adjusting the subsequent logic controls.

[0052] The description and application of the present invention here are illustrative, and it is not intended to limit the scope of the present invention to the above-mentioned embodiments. The effects or advantages involved in the specification may not be reflected in the actual experimental examples due to the uncertainty of specific condition parameters or other factors, and the effects or advantages are not used to limit the scope of the invention. The deformation and change of the embodiments disclosed here are possible, and the replacement of the embodiments and the various equivalent parts are well known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential features of the present invention. Other deformations and changes can be made to the embodiments disclosed here without departing from the scope and spirit of the present invention.

Claims

1. A constant voltage control circuit, characterized in that: The constant voltage control circuit comprises: A reference voltage generating circuit is used to generate a reference voltage according to a soft start enable signal, and in the soft start stage, the reference voltage gradually increases from an initial voltage to a preset voltage; a threshold generation circuit, whose input terminal is coupled to the output terminal of the reference voltage generation circuit, for generating a first threshold signal based on the reference voltage, wherein the difference between the reference voltage and the first threshold signal during at least a portion of the soft start phase is greater than the difference between the reference voltage and the first threshold signal during a steady-state operation state; and The dynamic response control circuit has an input terminal coupled to the output terminal of the threshold generation circuit and is used to trigger a fast dynamic response when a sampling signal representing the output voltage of the constant voltage driver is less than a first threshold signal.

2. The constant voltage control circuit according to claim 1, characterized in that: In a steady-state working state, the difference between the reference voltage and the first threshold signal is a preset value; during at least part of the soft start phase, the difference between the reference voltage and the first threshold signal is n times the preset value, where n>1.

3. The constant voltage control circuit according to claim 2, characterized in that: Within a preset time after the soft start is completed, the difference between the reference voltage and the first threshold signal gradually decreases from n times the preset value to the preset value.

4. The constant voltage control circuit according to claim 3, characterized in that: After a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal is a preset value.

5. The constant voltage control circuit according to claim 3, characterized in that: The value of n is selected so that a fast dynamic response is not triggered during the soft start phase under a preset load, and a fast dynamic response can be triggered during the soft start phase under a heavy load.

6. The constant voltage control circuit according to claim 1, characterized in that: After the soft start ends, the reference voltage is the preset voltage.

7. The constant voltage control circuit according to claim 1, characterized in that: The dynamic response control circuit includes a first comparison circuit, a first input terminal of the first comparison circuit is coupled to a threshold generation circuit to receive a first threshold signal, a second input terminal of the first comparison circuit receives a sampling signal, and an output terminal of the first comparison circuit outputs an undervoltage fast dynamic response control signal.

8. A constant voltage driver, characterized in that: The constant voltage driver comprises the constant voltage control circuit as claimed in any one of claims 1 to 7, and the constant voltage control circuit is used to control the output voltage of the constant voltage driver.

9. A constant voltage control method for controlling the output voltage of a constant voltage driver, characterized in that: The constant pressure control method comprises: Generate a reference voltage according to a soft start enable signal, and during the soft start phase, the reference voltage gradually increases from an initial voltage to a preset voltage; Generate a first threshold signal based on a reference voltage, wherein a difference between the reference voltage and the first threshold signal during at least a portion of the soft start phase is greater than a difference between the reference voltage and the first threshold signal during a steady-state operation state; and The triggering of the fast dynamic response is controlled according to the first threshold signal and the sampling signal representing the output voltage of the constant voltage driver. When the sampling signal is less than the first threshold signal, the fast dynamic response is triggered.

10. The constant voltage control method according to claim 9, characterized in that: In a steady-state working state, the difference between the reference voltage and the first threshold signal is a preset value; during at least part of the soft start phase, the difference between the reference voltage and the first threshold signal is n times the preset value, where n>1.

11. The constant voltage control method according to claim 10, characterized in that: Within a preset time after the soft start is completed, the difference between the reference voltage and the first threshold signal gradually decreases from n times the preset value to the preset value.

12. The constant voltage control method according to claim 11, characterized in that: After a preset time after the soft start ends, the difference between the reference voltage and the first threshold signal is a preset value.

13. The constant voltage control method according to claim 11, characterized in that: The value of n is selected so that a fast dynamic response is not triggered during the soft start phase under a preset load, and a fast dynamic response can be triggered during the soft start phase under a heavy load.

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