Switching power supply secondary side voltage sampling circuit and switching power supply

Abstract

The application relates to the technical field of semiconductors, in particular to a switching power supply secondary side voltage sampling circuit and a switching power supply. The switching power supply secondary side voltage sampling circuit comprises a feedback circuit; the feedback circuit is used for receiving and temperature-compensating and adjusting a secondary side output voltage of the switching power supply under a current temperature, obtaining an adjusted secondary side output voltage and outputting the same. The application can realize accurate control of the output voltage under different temperatures, and the circuit structure is simple and convenient to debug.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a secondary voltage sampling circuit for a switching power supply and a switching power supply. Background Technology

[0002] Currently, most methods for improving output voltage accuracy under three temperature conditions suffer from problems such as low output voltage accuracy, complex circuit design, and inconvenient debugging.

[0003] Therefore, there is an urgent need to provide a technical solution to address the above problems. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a secondary voltage sampling circuit for a switching power supply and a switching power supply.

[0005] In a first aspect, the present invention provides a secondary voltage sampling circuit for a switching power supply, the technical solution of which is as follows:

[0006] Includes: a feedback circuit; the feedback circuit is used for:

[0007] Receive and perform temperature compensation adjustment on the secondary output voltage of the switching power supply at the current temperature to obtain the adjusted secondary output voltage and output it.

[0008] The beneficial effects of the switching power supply secondary voltage sampling circuit of the present invention are as follows:

[0009] This invention enables precise control of the output voltage at different temperatures, and the circuit structure is simple and easy to debug.

[0010] Based on the above scheme, the secondary voltage sampling circuit of the switching power supply of the present invention can be further improved as follows.

[0011] In one alternative embodiment, the feedback circuit includes: a voltage input terminal, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, a first thermistor, a second thermistor, and a reference regulator;

[0012] The voltage input terminal is connected to one end of the first resistor, one end of the first thermistor, and one end of the fourth resistor. The other end of the fourth resistor is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to one end of the second capacitor and the first port of the reference regulator. The other end of the first resistor is connected to the other end of the first thermistor, one end of the third resistor, one end of the second resistor, one end of the first capacitor, and the second port of the reference regulator. The other end of the second capacitor is connected to the other end of the third resistor. The third port of the reference regulator is connected to the other end of the first capacitor and one end of the second thermistor and grounded. The other end of the second resistor is connected to the other end of the second thermistor.

[0013] In one alternative embodiment, the feedback circuit is specifically used for:

[0014] The secondary output voltage is received through the voltage input terminal, and the secondary output voltage is adjusted by temperature compensation through the first resistor, the second resistor, the first thermistor, the second thermistor, and the reference voltage regulator to obtain the adjusted secondary output voltage and output it.

[0015] In one alternative embodiment, the feedback circuit is specifically used for:

[0016] The secondary-side output voltage is adjusted to the standard secondary-side output voltage at normal temperature through the first resistor, the second resistor, the first thermistor, the second thermistor, and the reference voltage regulator, so as to obtain the adjusted secondary-side output voltage and output it.

[0017] In one alternative embodiment, the feedback circuit is specifically used for:

[0018] According to the target adjustment formula, and through the first resistor, the second resistor, the first thermistor, the second thermistor, and the reference regulator, the secondary-side output voltage is adjusted to the standard secondary-side output voltage at normal temperature to obtain and output the adjusted secondary-side output voltage; wherein, the target adjustment formula is: V out V is the target secondary-side output voltage. REF R1 is the reference voltage of the reference regulator, R2 is the resistance value of the first resistor, RT1 is the resistance value of the first thermistor, and RT2 is the resistance value of the second thermistor.

[0019] In one alternative embodiment, both the first thermistor and the second thermistor are negative temperature coefficient thermistors.

[0020] In one alternative embodiment, the method further includes: an isolation circuit; said isolation circuit is used for:

[0021] The system receives and generates a feedback signal based on the adjusted secondary output voltage, and outputs it to the PWM control chip of the switching power supply.

[0022] In one alternative embodiment, the isolation circuit includes: an optocoupler secondary side COPM terminal and an isolator connected across the fifth resistor.

[0023] In one alternative approach, the reference voltage is 2.5V.

[0024] In a second aspect, the present invention provides a switching power supply, which includes a secondary voltage sampling circuit as described in any of the switching power supplies of the present invention.

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0027] Figure 1 A schematic diagram of an embodiment of a switching power supply secondary voltage sampling circuit provided by the present invention is shown;

[0028] Figure 2 A schematic diagram of an embodiment of a switching power supply provided by the present invention is shown. Detailed Implementation

[0029] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0030] Figure 1 A schematic diagram of an embodiment of a switching power supply secondary voltage sampling circuit 10 provided by the present invention is shown. Figure 1 As shown, the secondary voltage sampling circuit 10 of the switching power supply includes: a feedback circuit 11; the feedback circuit 11 is used for:

[0031] The secondary-side output voltage of the switching power supply 20 at the current temperature is received and temperature-compensated for adjustment to obtain the adjusted secondary-side output voltage, which is then output. Wherein:

[0032] ①The current temperature can be one of high temperature, normal temperature, or low temperature.

[0033] ②The secondary output voltage is the secondary output voltage of the switching power supply 20 before adjustment.

[0034] Preferably, the feedback circuit 11 includes: a voltage input terminal U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2, a first thermistor RT1, a second thermistor RT2, and a reference voltage regulator U3. Wherein:

[0035] ① The voltage input terminal U1 is connected to one end of the first resistor R1, one end of the first thermistor RT1, and one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to one end of the second capacitor C2 and the first port of the reference regulator U3. The other end of the first resistor R1 is connected to the other end of the first thermistor RT1, one end of the third resistor R3, one end of the second resistor R2, one end of the first capacitor C1, and the second port of the reference regulator U3. The other end of the second capacitor C2 is connected to the other end of the third resistor R3. The third port of the reference regulator U3 is connected to the other end of the first capacitor C1 and one end of the second thermistor RT2 and grounded. The other end of the second resistor R2 is connected to the other end of the second thermistor RT2.

[0036] ② The first resistor R1 and the second resistor R2 are sampling resistors used to adjust the secondary output voltage. The first thermistor RT1 and the second thermistor RT2 are used to solve temperature drift.

[0037] ③ The output voltage can be set arbitrarily by adjusting the first thermistor RT1 and the second thermistor RT2.

[0038] Preferably, the feedback circuit 11 is specifically used for:

[0039] The secondary output voltage is received through the voltage input terminal U1, and the secondary output voltage is adjusted by temperature compensation through the first resistor R1, the second resistor R2, the first thermistor RT1, the second thermistor RT2 and the reference regulator U3 to obtain the adjusted secondary output voltage and output it.

[0040] Preferably, the feedback circuit 11 is specifically used for:

[0041] The secondary-side output voltage is adjusted to the standard secondary-side output voltage at normal temperature through the first resistor R1, the second resistor R2, the first thermistor RT1, the second thermistor RT2, and the reference voltage regulator U3, so as to obtain the adjusted secondary-side output voltage and output it.

[0042] It should be noted that due to the different temperature characteristics of different electronic components and the design of loop parameters, the output voltage may be higher or lower than that at room temperature under different temperature conditions. Therefore, by designing the feedback circuit 11, the output voltage can be accurately controlled at different temperatures.

[0043] Preferably, the feedback circuit 11 is specifically used for:

[0044] According to the target adjustment formula, and through the first resistor R1, the second resistor R2, the first thermistor RT1, the second thermistor RT2, and the reference regulator U3, the secondary-side output voltage is adjusted to the standard secondary-side output voltage at normal temperature to obtain the adjusted secondary-side output voltage and output it. Wherein:

[0045] ①The target adjustment formula is: V out V is the target secondary-side output voltage. REF R1 is the reference voltage of the reference regulator, R2 is the resistance value of the first resistor, R1 is the resistance value of the second resistor, RT1 is the resistance value of the first thermistor, and RT2 is the resistance value of the second thermistor.

[0046] ② Both the first thermistor RT1 and the second thermistor RT2 are negative temperature coefficient thermistors. The resistance of the thermistors decreases at high temperatures and increases at low temperatures.

[0047] Preferably, it further includes: an isolation circuit 12; the isolation circuit 12 is used for:

[0048] The system receives and generates a feedback signal based on the adjusted secondary-side output voltage, and outputs it to the PWM control chip of the switching power supply 20. Wherein:

[0049] ①The isolation circuit 12 includes: the COPM terminal of the optocoupler secondary side and the isolator U2.

[0050] ②Isolator U2 is connected across the fifth resistor R5, and the COPM terminal of the optocoupler is connected to the PWM control chip.

[0051] ③ The reference voltage is 2.5V.

[0052] The technical solution of this embodiment can achieve precise control of the output voltage at different temperatures, and the circuit structure is simple and easy to debug.

[0053] Figure 2 A schematic diagram of an embodiment of a switching power supply 20 provided by the present invention is shown. For example... Figure 2 As shown, the switching power supply 20 includes a secondary voltage sampling circuit 10 of the present invention.

[0054] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0055] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A secondary voltage sampling circuit for a switching power supply, characterized in that, include: Feedback circuit; The feedback circuit is used for: Receive and perform temperature compensation adjustment on the secondary output voltage of the switching power supply at the current temperature to obtain and output the adjusted secondary output voltage; The feedback circuit includes: a voltage input terminal, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, a first thermistor, a second thermistor, and a reference voltage regulator; The voltage input terminal is connected to one end of the first resistor, one end of the first thermistor, and one end of the fourth resistor. The other end of the fourth resistor is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to one end of the second capacitor and the first port of the reference regulator. The other end of the first resistor is connected to the other end of the first thermistor, one end of the third resistor, one end of the second resistor, one end of the first capacitor, and the second port of the reference regulator. The other end of the second capacitor is connected to the other end of the third resistor. The third port of the reference regulator is connected to the other end of the first capacitor and one end of the second thermistor and grounded. The other end of the second resistor is connected to the other end of the second thermistor.

2. The switching power supply secondary voltage sampling circuit according to claim 1, characterized in that, The feedback circuit is specifically used for: The secondary output voltage is received through the voltage input terminal, and the secondary output voltage is adjusted by temperature compensation through the first resistor, the second resistor, the first thermistor, the second thermistor, and the reference voltage regulator to obtain the adjusted secondary output voltage and output it.

3. The switching power supply secondary voltage sampling circuit according to claim 2, characterized in that, The feedback circuit is specifically used for: The secondary-side output voltage is adjusted to the standard secondary-side output voltage at normal temperature through the first resistor, the second resistor, the first thermistor, the second thermistor, and the reference voltage regulator, so as to obtain the adjusted secondary-side output voltage and output it.

4. The switching power supply secondary voltage sampling circuit according to claim 3, characterized in that, The feedback circuit is specifically used for: According to the target adjustment formula, and through the first resistor, the second resistor, the first thermistor, the second thermistor, and the reference regulator, the secondary-side output voltage is adjusted to the standard secondary-side output voltage at normal temperature to obtain and output the adjusted secondary-side output voltage; wherein, the target adjustment formula is: ; The target secondary output voltage, The reference voltage of the reference regulator is [the voltage at which the reference regulator is located]. Let be the resistance value of the first resistor. This is the resistance value of the second resistor. The resistance value of the first thermistor. This is the resistance value of the second thermistor.

5. The switching power supply secondary voltage sampling circuit according to any one of claims 1 to 4, characterized in that, Both the first thermistor and the second thermistor are negative temperature coefficient thermistors.

6. The switching power supply secondary voltage sampling circuit according to claim 1, characterized in that, Also includes: Isolation circuit; the isolation circuit is used for: The system receives and generates a feedback signal based on the adjusted secondary output voltage, and outputs it to the PWM control chip of the switching power supply.

7. The switching power supply secondary voltage sampling circuit according to claim 6, characterized in that, The isolation circuit includes: the COPM terminal of the optocoupler secondary side and an isolator, the isolator being connected across the fifth resistor.

8. The switching power supply secondary voltage sampling circuit according to claim 4, characterized in that, The reference voltage is 2.5V.

9. A switching power supply, characterized in that, Includes the secondary voltage sampling circuit of the switching power supply as described in any one of claims 1 to 8.

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