CN114301286B - Class III compensation network and switching power supply - Google Patents
Class III compensation network and switching power supply Download PDFInfo
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- CN114301286B CN114301286B CN202111678580.6A CN202111678580A CN114301286B CN 114301286 B CN114301286 B CN 114301286B CN 202111678580 A CN202111678580 A CN 202111678580A CN 114301286 B CN114301286 B CN 114301286B
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Abstract
The invention discloses a III class compensation network and a switching power supply, wherein the III class compensation network comprises: a voltage dividing branch and a compensating branch; the voltage dividing branch is connected between the output end and the ground and is provided with a voltage dividing node connected with the reference voltage; the compensation branch circuit comprises a first capacitor and a second capacitor which are connected in series between the output end and the voltage division node, a third resistor, one end of which is connected to the connection part of the first capacitor and the second capacitor, the other end of which is connected with the third resistor, and a third capacitor of the COMP end of the switching power supply, wherein the other end of the third capacitor is grounded. According to the III-class compensation network and the switching power supply, the voltage output by the output end can meet the requirement by adjusting the voltage dividing branch and combining the given reference voltage; the compensation of the double zero points and the double pole points is carried out by the compensation branch circuit and the voltage dividing branch circuit, so that when the voltage output by the required output end is smaller and approaches to the reference voltage, the compensation branch circuit can also have enough gain margin and phase margin, and the stability of the system is ensured.
Description
Technical Field
The present invention relates to the field of integrated circuits, and more particularly, to a class iii compensation network and a switching power supply.
Background
In order to guarantee the output gain margin as well as the phase margin of the switching power supply, it is often necessary to introduce a compensation network. With the change of application scenes, customers have different demands on the magnitude of the output voltage of the switching power supply. When the output voltage required by the customer is smaller and is close to the reference voltage of the switching power supply, the compensation effect of the existing III compensation network is weakened, and enough gain margin and phase margin cannot be ensured.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.
Disclosure of Invention
The invention aims to provide a III-class compensation network and a switching power supply, which can ensure enough gain margin and phase margin when the required output voltage is smaller and is close to the reference voltage of the switching power supply.
To achieve the above object, an embodiment of the present invention provides a class iii compensation network for providing variable double zero and double pole compensation in a frequency response of a switching power supply, including: a voltage dividing branch and a compensating branch; wherein,
The voltage dividing branch is connected between the output end VOUT and the ground, and is provided with a voltage dividing node connected with the reference voltage V REF;
The compensation branch circuit comprises a first capacitor C1, a second capacitor C2, a third resistor R3 and a third capacitor C3, wherein the first capacitor C1 and the second capacitor C2 are connected in series between an output end VOUT and a voltage dividing node, the joint of the first capacitor C1 and the second capacitor C2 is simultaneously connected with one end of the third resistor R3, the other end of the third resistor R3 is connected with the COMP end of the switching power supply and one end of the third capacitor C3, and the other end of the third capacitor C3 is grounded.
In one or more embodiments of the present invention, the voltage dividing branch includes a first resistor R1 and a second resistor R2 connected in series.
In one or more embodiments of the present invention, the second resistance R2 is equal to or greater than the first resistance R1.
In one or more embodiments of the invention, the second resistance R2 is substantially greater than the first resistance R1.
In one or more embodiments of the invention, the transfer function of the class iii compensation network is:
in one or more embodiments of the present invention, the first resistor R1 and the second resistor R2 are each a variable resistor.
In one or more embodiments of the present invention, the first capacitor C1 and the second capacitor C2 are both variable capacitors.
In one or more embodiments of the present invention, the third resistor R3 is a variable resistor.
In one or more embodiments of the present invention, the third capacitor C3 is a variable capacitor.
The invention also provides a switching power supply, which comprises the III-class compensation network.
Compared with the prior art, the III-class compensation network and the switching power supply can enable the voltage output by the output end VOUT to meet the requirement by adjusting the voltage dividing branch and combining the given reference voltage; the compensation of the double zero points and the double pole points is carried out by the compensation branch circuit and the voltage dividing branch circuit, so that when the voltage output by the required output end VOUT is smaller and approaches to the reference voltage, the compensation branch circuit can have enough gain margin and phase margin, and the stability of the system is ensured.
Drawings
Fig. 1 is a schematic circuit diagram of a class iii compensation network according to one embodiment of the invention.
Fig. 2 is a graph of gain and phase waveforms under double zero and double pole compensation according to an embodiment of the present invention.
Fig. 3 is a schematic circuit diagram of a compensation network according to a comparative example of the present invention.
Fig. 4 is a graph of gain and phase waveforms at single zero and single pole compensation according to a comparative example of the present invention.
Detailed Description
The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or components.
Example 1
As shown in fig. 1, a class iii compensation network is provided for providing variable double zero and double pole compensation in the frequency response of a switching power supply 10.
The class III compensation network comprises: a voltage dividing branch 20 and a compensating branch 30.
The voltage dividing branch 20 is connected between the output terminal VOUT and ground, and the voltage dividing branch 20 has a voltage dividing node connected to the reference voltage VREF. The voltage dividing branch 20 includes a first resistor R1 and a second resistor R2 connected in series, where one end of the first resistor R1 is connected to the output terminal VOUT, and the other end is connected to one end of the second resistor R2 to form a voltage dividing node and connected to the reference voltage V REF. The first resistor R1 and the second resistor R2 are both variable resistors.
The compensating branch 30 includes a first capacitor C1, a second capacitor C2, a third resistor R3 and a third capacitor C3, where the first capacitor C1 and the second capacitor C2 are connected in series between the output terminal VOUT and the voltage dividing node, the junction of the first capacitor C1 and the second capacitor C2 is simultaneously connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to the COMP terminal (compensating terminal) of the switching power supply 10 and one end of the third capacitor C3, and the other end of the third capacitor C3 is grounded. The first capacitor C1, the second capacitor C2 and the third capacitor C3 are all variable capacitors, and the third resistor R3 is a variable resistor.
In this embodiment, the reference voltage V REF is a fixed value and is output from the VSENSE terminal of the switching power supply 10, so that the second resistor R2 and the first resistor R1 can be adjusted to meet the required voltage output from the output terminal VOUT. In particular, the second resistor R2 and the first resistor R1 are adjusted when the voltage to be output is relatively small and is close to the reference voltage V REF, and the second resistor R2 is generally equal to or greater than (>) or much greater than (>) the first resistor R1.
The transfer function of the class III compensation network is:
From the transfer function described above, there is a first zero ω z1, a second zero ω z2, a first pole ω p1, and a second pole ω p2: According to the zero point and the pole to be adjusted, the corresponding zero point and pole are adjusted by adjusting the size of one or more elements of the first resistor R1, the second resistor R2, the first capacitor C1, the second capacitor C2, the third resistor R3 and the third capacitor C3.
In addition, it can be seen that, when the second resistor R2 is greater than (equal to) or greater than (>) the first resistor R1, the second zero point ω z2 and the second pole point ω p2 cannot be offset due to the presence of the first capacitor C1 and the second capacitor C2, so that the compensation effect still exists.
As shown in fig. 2, fig. 2 is a graph of gain and phase waveforms under compensation of the first zero ω z1, the second zero ω z2, the first pole ω p1, and the second pole ω p2. It can be seen from fig. 2 that under the compensation of the first zero point ω z1, the second zero point ω z2, the first pole ω p1 and the second pole ω p2, the compensation effect is very good under different output voltages, i.e. a very sufficient compensation effect can be achieved in a large output voltage range. In addition, in particular, even in the case where the second resistance R2 is equal to or greater than (>) or much greater than (>) the first resistance R1 due to the required output voltage being relatively small and close to the reference voltage V REF, there is still sufficient gain margin and phase margin, and the larger the ratio of the pole to the zero point is, the better the compensation effect is.
Other embodiments also disclose a switching power supply comprising the class III compensation network described above.
Comparative example 1
As shown in fig. 3, a conventional class iii compensation network circuit diagram includes a resistor R8 and a resistor R9 connected in series, a capacitor C11 connected in parallel with the resistor R8, a capacitor C6 connected between the COMP terminal and ground, and a resistor R4 and a capacitor C4 connected in series between the COMP terminal and ground. The transfer function of the III class compensation network circuit diagram is as follows:
it can be seen that there is a third zero ω z3, a fourth zero ω z4, a third pole ω p3, and a fourth pole ω p4:
In addition, it can be seen that, in the case where the resistance R9 is equal to or greater than the resistance R8, the fourth zero point ω z4 and the fourth point ω p4 can cancel each other, and the compensation effect is lost.
As shown in fig. 4, fig. 4 is a gain and phase waveform diagram under compensation of the third zero point ω z3 and the third pole point ω p3. It can be seen from fig. 4 that only under the compensation of the third zero point ω z3 and the third pole point ω p3, under the condition that the resistor R9 is equal to or greater than (>) or much greater than (>) the resistor R8 because the required output voltage is relatively small and is close to the reference voltage V REF, the compensation effect is weak.
The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (9)
1. A class iii compensation network for providing variable double zero and double pole compensation in the frequency response of a switching power supply, comprising: a voltage dividing branch and a compensating branch; wherein,
The voltage dividing branch circuit is connected between the output end VOUT and the ground, the voltage dividing branch circuit is provided with a voltage dividing node connected with the reference voltage V REF, and the voltage dividing branch circuit comprises a first resistor R1 and a second resistor R2 which are connected in series to form the voltage dividing node;
The compensation branch circuit comprises a first capacitor C1, a second capacitor C2, a third resistor R3 and a third capacitor C3, wherein the first capacitor C1 and the second capacitor C2 are connected in series between an output end VOUT and a voltage dividing node, the joint of the first capacitor C1 and the second capacitor C2 is simultaneously connected with one end of the third resistor R3, the other end of the third resistor R3 is connected with the COMP end of the switching power supply and one end of the third capacitor C3, and the other end of the third capacitor C3 is grounded.
2. The class iii compensation network of claim 1, wherein the second resistance R2 is equal to or greater than the first resistance R1.
3. The class iii compensation network of claim 1, wherein the second resistance R2 is substantially greater than the first resistance R1.
4. The class iii compensation network of claim 1, wherein the class iii compensation network has a transfer function of:
5. The class iii compensation network of claim 1, wherein the first resistor R1 and the second resistor R2 are each variable resistors.
6. The class iii compensation network of claim 1, wherein the first capacitor C1 and the second capacitor C2 are each variable capacitors.
7. The class iii compensation network of claim 1, wherein the third resistor R3 is a variable resistor.
8. The class iii compensation network of claim 1, wherein the third capacitance C3 is a variable capacitance.
9. A switching power supply comprising a class iii compensation network according to any one of claims 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111678580.6A CN114301286B (en) | 2021-12-31 | 2021-12-31 | Class III compensation network and switching power supply |
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| CN202111678580.6A CN114301286B (en) | 2021-12-31 | 2021-12-31 | Class III compensation network and switching power supply |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10819210B1 (en) * | 2019-06-28 | 2020-10-27 | Acer Incorporated | Power supply apparatus capable of increasing feedback response speed |
| CN112000166A (en) * | 2019-05-27 | 2020-11-27 | 艾普凌科有限公司 | Voltage regulator |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US9948185B2 (en) * | 2016-06-10 | 2018-04-17 | Dialog Semiconductor (Uk) Limited | Fast-transient switching converter with type III compensation |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112000166A (en) * | 2019-05-27 | 2020-11-27 | 艾普凌科有限公司 | Voltage regulator |
| US10819210B1 (en) * | 2019-06-28 | 2020-10-27 | Acer Incorporated | Power supply apparatus capable of increasing feedback response speed |
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