Circuit beneficial to improving reliability of switching converter

Abstract

The utility model relates to the technical field of circuits, in particular to a circuit favorable for improving the reliability of a switching converter, which is characterized in that one end of an access for discharging a capacitor is connected with a III-type compensation network circuit, the other end of the access for discharging the capacitor is grounded, and the access for discharging the capacitor comprises a resistor R7 and a diode D1, the III-type compensation network circuit comprises a capacitor C3, a first pin of a resistor R7 is connected with a first pin of the capacitor C3, a second pin of the resistor R7 is connected with a first pin of a diode D1, and a second pin of the diode D1 is connected with GND. Compared with the prior art, the circuit beneficial to improving the reliability of the switching converter is additionally provided with a path for discharging the differential capacitor under the condition that the dynamic response of a feedback loop of the switching converter is not influenced, so that negative voltage is prevented from being generated at the reverse end of the operational amplifier when the output of the switching power supply is short-circuited; therefore, the abnormal output of the feedback network during output short circuit is avoided, and the reliability of the converter during output short circuit is improved.

Description

Technical field

[0001] The utility model relates to the technical field of circuits, and in particular to a circuit which is beneficial to improving the reliability of a switching converter. [Background Technology]

[0002] In existing Type III compensation network circuits, when an output short circuit occurs, the negative voltage at the reverse terminal of the operational amplifier causes the output voltage of the op amp to drop sharply, causing the current in the feedback optocoupler to suddenly increase. At this point, the primary-side control IC stops outputting. Most existing switching power supply control ICs have a time delay in short-circuit detection. This means that when an output short circuit occurs, the IC stops outputting not because the short circuit is detected, but because the feedback signal increases abnormally. In this case, restarting the IC fails to achieve a soft start, significantly increasing the converter's reliability during an output short circuit and, in severe cases, even causing the converter to crash. [Utility Model Content]

[0003] In order to overcome the above problems, the present invention proposes a circuit that can effectively solve the above problems and is beneficial to improving the reliability of the switching converter.

[0004] The present invention provides a technical solution to solve the above-mentioned technical problems, which is to provide a circuit that is beneficial to improving the reliability of a switching converter, including a type III compensation network circuit and a path for discharging a capacitor, one end of the path for discharging the capacitor is connected to the type III compensation network circuit, and the other end of the path for discharging the capacitor is grounded; the path for discharging the capacitor includes a resistor R7 and a diode D1, the type III compensation network circuit includes a capacitor C3, pin 1 of the resistor R7 is connected to pin 1 of the capacitor C3, pin 2 of the resistor R7 is connected to pin 1 of the diode D1, and pin 2 of the diode D1 is connected to GND.

[0005] Preferably, the type III compensation network circuit includes a resistor R6, one end of the resistor R6 is connected to pin 1 of the capacitor C3, and the other end of the resistor R6 is connected to point A.

[0006] Preferably, the type III compensation network circuit includes a chip U1B and a resistor R5, wherein pin 2 of the resistor R5 is connected to pin 6 of the chip U1B, pin 1 of the resistor R5 is connected to GND, and pin 2 of the resistor R5 is connected to point A.

[0007] Preferably, the resistance of the resistor R7 is smaller than the sum of the resistances of the resistors R6 and R5.

[0008] Compared with the prior art, the circuit of the utility model is beneficial for improving the reliability of the switching converter. It adds a discharge path for the differential capacitor without affecting the dynamic response of the feedback loop of the switching converter, thereby avoiding the generation of negative voltage at the reverse end of the operational amplifier when the output of the switching power supply is short-circuited, thereby avoiding abnormal output of the feedback network when the output is short-circuited, and improving the reliability of the converter when the output is short-circuited.

Brief Description of the Drawings

[0009] Figure 1 A schematic diagram of a type III compensation network circuit of a switching converter feedback circuit in the prior art;

[0010] Figure 2 The utility model is a schematic diagram of a circuit that is beneficial for improving the reliability of a switching converter. [Specific implementation method]

[0011] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0012] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are limited to relative positions on a specified view, rather than absolute positions.

[0013] In addition, the terms "first," "second," and so on, used in this utility model are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0014] See also Figure 1 and Figure 2 The circuit of the utility model is beneficial for improving the reliability of the switching converter, including a type III compensation network circuit of the prior art and a path for discharging a capacitor, one end of the path for discharging the capacitor is connected to the type III compensation network circuit, and the other end of the path for discharging the capacitor is grounded.

[0015] The path for discharging the capacitor includes a resistor R7 and a diode D1. The type III compensation network circuit includes a capacitor C3. Pin 1 of the resistor R7 is connected to pin 1 of the capacitor C3, pin 2 of the resistor R7 is connected to pin 1 of the diode D1, pin 2 of the diode D1 is connected to GND, and pin 2 of the capacitor C3 is connected to VOUT.

[0016] The type III compensation network circuit includes a resistor R6, one end of the resistor R6 is connected to pin 1 of the capacitor C3, and the other end of the resistor R6 is connected to point A.

[0017] The type III compensation network circuit includes a chip U1B and a resistor R5, wherein pin 2 of the resistor R5 is connected to pin 6 of the chip U1B, pin 1 of the resistor R5 is connected to GND, and pin 2 of the resistor R5 is connected to point A.

[0018] The resistance of the resistor R7 is smaller than the sum of the resistances of the resistors R6 and R5.

[0019] The type III compensation network circuit includes a capacitor C2, a resistor R3 and a resistor R4. The resistor R3 and the resistor R4 are connected, one end of the resistor R3 is connected to VOUT, and one end of the capacitor C2 and one end of the resistor R4 are connected to point A.

[0020] The type III compensation network circuit includes a capacitor C1 and a resistor R2. The resistor R2 is connected to the capacitor C1. One end of the capacitor C1 is connected to point A.

[0021] The type III compensation network circuit includes a resistor R1 and a feedback optocoupler OT1A. One end of the resistor R1 is connected to VCC, and the other end of the resistor R1 is connected to the feedback optocoupler OT1A. The feedback optocoupler OT1A is connected to the capacitor C2 and the resistor R2 respectively.

[0022] The utility model is beneficial to improving the reliability of the switching converter circuit. The main function is to solve the problem of abnormal feedback signal caused by negative voltage at the reverse end of the operational amplifier of the switching converter feedback circuit type III compensation network when the switching converter output is short-circuited.

[0023] In the prior art, i.e., in a Type III compensation network circuit without R7 and D1, when the switching converter output shorts, the transformer has not yet stopped outputting, and in actual applications, the output port circuit within the converter has impedance. Therefore, VOUT gradually drops to GND over time. During this process, the energy on capacitor C3 can only be discharged through the output port and the loop formed by R5, R6, and C3, forming current I1. The current I2 formed by VOUT flowing through R3, R4, and R5 to GND gradually decreases during this process. When I1 exceeds I2, a negative voltage is generated at point A. For a single-supply operational amplifier, although the reverse terminal voltage is still lower than the forward terminal voltage, the output terminal will switch from a high level to a low level, causing an abnormal increase in the current in the feedback optocoupler OT1A.

[0024] The circuit of the present invention, which is beneficial for improving the reliability of a switching converter, adds a discharge path R7 (the value of R7 is much smaller than R6+R5) and D1 for C3. When VOUT drops due to an output short circuit, the energy on capacitor C3 is discharged mainly through the loop formed by D1, R7, C3, and the output port. This greatly reduces current I1, preventing I1 from exceeding I2. Negative voltage no longer appears at point A, avoiding feedback network anomalies. At the same time, the presence of D1 blocks the flow of AC signals, so the newly added D1 and R7 network will not have any impact on the feedback network.

[0025] Compared with the prior art, the circuit of the utility model is beneficial for improving the reliability of the switching converter. It adds a discharge path for the differential capacitor without affecting the dynamic response of the feedback loop of the switching converter, thereby avoiding the generation of negative voltage at the reverse end of the operational amplifier when the output of the switching power supply is short-circuited, thereby avoiding abnormal output of the feedback network when the output is short-circuited, and improving the reliability of the converter when the output is short-circuited.

[0026] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications, equivalent replacements and improvements made within the concept of the present invention should be included in the patent protection scope of the present invention.

Claims

1. A circuit for improving the reliability of a switching converter, characterized in that: It includes a type III compensation network circuit and a path for discharging a capacitor, one end of the path for discharging the capacitor is connected to the type III compensation network circuit, and the other end of the path for discharging the capacitor is grounded; The path for discharging the capacitor includes a resistor R7 and a diode D1. The type III compensation network circuit includes a capacitor C3. Pin 1 of the resistor R7 is connected to pin 1 of the capacitor C3. Pin 2 of the resistor R7 is connected to pin 1 of the diode D1. Pin 2 of the diode D1 is connected to GND.

2. The circuit for improving the reliability of a switching converter according to claim 1, wherein: The type III compensation network circuit includes a resistor R6, one end of the resistor R6 is connected to pin 1 of the capacitor C3, and the other end of the resistor R6 is connected to point A.

3. The circuit for improving the reliability of a switching converter according to claim 2, wherein: The type III compensation network circuit includes a chip U1B and a resistor R5, wherein pin 2 of the resistor R5 is connected to pin 6 of the chip U1B, pin 1 of the resistor R5 is connected to GND, and pin 2 of the resistor R5 is connected to point A.

4. The circuit for improving the reliability of a switching converter according to claim 3, wherein: The resistance of the resistor R7 is smaller than the sum of the resistances of the resistors R6 and R5.

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