An anti-oscillation circuit and power supply thereof

Abstract

The utility model discloses an anti -oscillation circuit and power supply thereof. The anti -oscillation circuit includes voltage dividing unit, temperature response unit and voltage regulation unit, voltage dividing unit is connected with the input of power module and voltage regulation unit, is used for dividing voltage of power module input voltage according to the preconcerted ratio, provides voltage dividing voltage for voltage regulation unit, temperature response unit is connected with the input of power module and voltage regulation unit, is used for providing bias voltage for voltage regulation unit, and adjusts bias voltage according to environmental temperature change, voltage regulation unit still is connected with the enable end of power module, is used for adjusting own on -resistance according to bias voltage, thereby adjusts the voltage of power module enable end. The utility model embodiment can automatically compensate the temperature drift of power module enable threshold under different temperature environment, effectively prevents the power module from generating oscillation near the under -voltage point, improves the working stability and reliability of power module under extreme temperature environment.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to an anti-oscillation circuit and its power supply. Background Technology

[0002] In the power management systems of electronic devices, DC-DC power modules are widely used in various voltage conversion applications. Typically, a DC-DC power module is designed with an EN (Enable) pin to control the chip's on / off state. This pin corresponds to the on-th voltage threshold Vth_en and the off-th voltage threshold Vth_off. Simultaneously, the input terminal Vin of the power module also features an UVLO (Under Voltage Lock Out) undervoltage lockout protection mechanism. When the input voltage reaches the undervoltage point, the chip will be shut down. The on-th voltage for UVLO is Vlo_on, and the off-th voltage is Vlo_off.

[0003] Under normal operating conditions, to turn on the power module, the voltage at the input terminal Vin must be greater than the maximum value of Vth_en and Vlo_on; to turn off the power module, the voltage at Vin must be lower than the maximum value of Vth_off and Vlo_off. However, in practical applications, the power module exhibits an oscillation problem during power-down: when the voltage at Vin drops to near the input undervoltage point, the chip triggers undervoltage protection and shuts down. But when the threshold space for power module turn-on and off is insufficient, the rebound voltage at the input terminal can easily exceed the turn-on voltage, causing the power module to turn on again, resulting in continuous switching oscillations that severely affect the stability and reliability of the power module.

[0004] To address the undervoltage point oscillation problem, existing technologies typically employ a voltage divider circuit between Vin and EN. By using a voltage divider resistor, Vth_en is effectively increased, thereby increasing Vin_on or decreasing Vin_off. This allows for a larger threshold space between the power module's on and off states, thus suppressing oscillation.

[0005] However, existing fixed voltage divider schemes have significant shortcomings: in extreme operating scenarios, such as low temperatures of -40°C or high temperatures of 125°C, the threshold of the EN pin experiences significant temperature drift, causing changes in Vth_en and Vth_off. Particularly in high-temperature environments, Vth_off tends to decrease, rendering the originally designed fixed voltage divider resistor parameters unable to adapt to temperature variations, and oscillation problems persist. Furthermore, in extreme environments, the requirements for power module stability are often higher, making the limitations of existing technologies even more pronounced. Utility Model Content

[0006] The main technical problem solved by this utility model embodiment is to provide an anti-oscillation circuit and its power supply, which can solve at least some of the defects of existing power supply modules.

[0007] In a first aspect, this utility model provides an anti-oscillation circuit, comprising: a voltage divider unit, a temperature sensing unit, and a voltage regulation unit; the voltage divider unit is connected to the input terminal of the power module and the voltage regulation unit, the temperature sensing unit is connected to the input terminal of the power module and the voltage regulation unit, and the voltage regulation unit is also connected to the enable terminal of the power module; the voltage divider unit is used to divide the input voltage of the power module according to a preset ratio to provide a divided voltage to the voltage regulation unit; the temperature sensing unit is used to provide a bias voltage to the voltage regulation unit and is also used to adjust the bias voltage according to changes in ambient temperature; the voltage regulation unit is used to adjust its own on-resistance according to the bias voltage, thereby adjusting the voltage at the enable terminal of the power module.

[0008] Optionally, when the ambient temperature rises, the temperature sensing unit increases the bias voltage to reduce the on-resistance of the voltage regulation unit, thereby reducing the voltage at the enable terminal of the power module; when the ambient temperature decreases, the temperature sensing unit decreases the bias voltage to increase the on-resistance of the voltage regulation unit, thereby increasing the voltage at the enable terminal of the power module.

[0009] Optionally, the voltage divider unit includes resistors R1 and R2. The first end of resistor R1 is connected to the input terminal of the power supply module, the second end of resistor R1 is connected to the first end of resistor R2 and the input terminal of the voltage regulation unit, and the second end of resistor R2 is connected to reference ground.

[0010] Optionally, the temperature sensing unit includes a thermistor Rntc and a resistor R3. The first end of the resistor R3 is connected to the input terminal of the power module, and the second end of the resistor R3 is connected to the first end of the thermistor Rntc and the control terminal of the voltage regulation unit. The second end of the thermistor Rntc is connected to a reference ground.

[0011] Optionally, the physical distance between the thermistor Rntc and the power module is less than or equal to 2mm.

[0012] Optionally, the thermistor Rntc is a negative temperature coefficient thermistor.

[0013] Optionally, the voltage regulation unit includes a switching transistor Q1, the gate of which is connected to the output terminal of the temperature sensing unit, the drain of which is connected to the output terminal of the voltage divider unit, and the source of which is connected to the enable pin of the power supply module.

[0014] Optionally, the gate threshold voltage of the switch Q1 is less than or equal to 1.5V.

[0015] Optionally, the switching transistor Q1 is an N-channel metal-oxide-semiconductor field-effect transistor.

[0016] Secondly, embodiments of the present invention provide a power supply, including: a power module; and an anti-oscillation circuit as described in the first aspect.

[0017] The beneficial effects of this utility model embodiment are: unlike the prior art, this utility model embodiment can automatically compensate for the temperature drift of the power module enable threshold under different temperature environments, effectively prevent the power module from oscillating near the undervoltage point, and improve the working stability and reliability of the power module under extreme temperature environments. Attached Figure Description

[0018] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0019] Figure 1 This is the circuit diagram of the voltage divider circuit at the enable terminal of an existing power module.

[0020] Figure 2 This is a schematic diagram of the structure of an anti-oscillation circuit provided by an embodiment of the present invention;

[0021] Figure 3 This is a circuit diagram of an anti-oscillation circuit provided by an embodiment of the present invention. Detailed Implementation

[0022] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this specification are for illustrative purposes only.

[0023] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0024] Reference Figure 1 , Figure 1 The circuit diagram of the voltage divider circuit at the enable terminal of a power module in the prior art is shown. For example... Figure 1 As shown, the existing voltage divider circuit includes resistors R1 and R2. The first terminal of resistor R1 is connected to the input voltage Vin, and the second terminal of resistor R1 is connected to the first terminal of resistor R2. This connection point serves as the voltage divider node and is connected to the enable terminal EN of the power module. The second terminal of resistor R2 is connected to the reference ground GND. Resistors R1 and R2 are connected in series between the input voltage Vin and the reference ground GND, forming a basic resistor voltage divider circuit.

[0025] In this existing technical solution, the voltage of the enable terminal EN is obtained by dividing the input voltage Vin through resistors R1 and R2, with the voltage division relationship being: VEN = Vin × R2 / (R1+R2). By pre-setting the resistance ratio of resistors R1 and R2, the input voltage Vin can be distributed according to a fixed ratio, thereby controlling the magnitude of the voltage of the enable terminal EN.

[0026] The working mechanism of this voltage divider circuit is as follows: when the input voltage Vin fluctuates near the undervoltage protection point, the voltage applied to the enable terminal EN is reduced through the voltage divider effect, which is equivalent to increasing the effective turn-on threshold of the power module, thereby increasing the threshold window between the turn-on voltage and the turn-off voltage, preventing the power module from being triggered to turn on again when the input voltage rebounds, and avoiding switching oscillation.

[0027] However, this existing technology has a significant drawback: the resistance values ​​of resistors R1 and R2 are fixed, and the voltage division ratio does not adjust with changes in environmental conditions. In practical applications, especially within a wide temperature range of -40°C to 125°C, the enable threshold voltage inside the power module will experience temperature drift. Particularly in high-temperature environments, the shutdown threshold Vth_off typically decreases, and the fixed voltage division ratio cannot compensate for this. This causes the originally designed anti-oscillation effect to fail under extreme temperature conditions, and the oscillation problem reappears, affecting the reliability and stability of the power module.

[0028] Therefore, existing fixed voltage divider technology cannot adapt to the impact of temperature changes on the threshold characteristics of power modules, and has significant limitations in applications requiring wide temperature range operation. To solve the above problems, this utility model provides an anti-oscillation circuit, the schematic diagram of which is shown below. Figure 2 As shown, the anti-oscillation circuit 10 is connected between the power module 20 and the external power supply to prevent the power module 20 from oscillating during operation. The anti-oscillation circuit 10 includes a voltage divider unit 110, a temperature sensing unit 120, and a voltage regulation unit 130.

[0029] The voltage divider unit 110 establishes an electrical connection with the input terminal of the power module 20, and is also connected to the voltage regulation unit 130. The main function of the voltage divider unit 110 is to receive the input voltage from the outside and divide the input voltage according to a preset ratio, thereby providing the voltage regulation unit 130 with a divided voltage.

[0030] Specifically, the temperature sensing unit 120 is also connected to the input terminal of the power module 20, and it is also electrically connected to the voltage regulation unit 130. The temperature sensing unit 120 has a dual function: on the one hand, it provides the bias voltage required for the voltage regulation unit 130 to operate; on the other hand, it can sense changes in the ambient temperature and adjust the provided bias voltage accordingly. When the ambient temperature changes, the temperature sensing unit 120 can respond to the temperature change in real time and adjust the magnitude of the output bias voltage through its internal temperature-sensitive mechanism.

[0031] The voltage regulation unit 130 not only establishes an electrical connection with the voltage divider unit 110 and the temperature sensing unit 120, but also forms a crucial connection with the enable terminal of the power module 20. The function of the voltage regulation unit 130 is to dynamically adjust its own on-resistance characteristics based on the bias voltage signal received from the temperature sensing unit 120, thereby controlling the magnitude of the voltage transmitted to the enable terminal of the power module 20.

[0032] In some embodiments of this application, the anti-oscillation circuit 10 exhibits significant temperature adaptive characteristics. When the ambient temperature rises, the temperature sensing unit 120 is able to sensitively detect the trend of temperature increase. In response to the environmental change of rising temperature, the temperature sensing unit 120 adapts to the new temperature conditions by increasing the output bias voltage. The increase in bias voltage directly affects the voltage regulation unit 130, causing the on-resistance of the voltage regulation unit 130 to decrease accordingly.

[0033] When the on-resistance of the voltage regulation unit 130 decreases, the electrical characteristics of the circuit change accordingly, ultimately reducing the voltage transmitted to the enable terminal of the power module 20. By reducing the enable terminal voltage, the anti-oscillation circuit 10 can effectively compensate for changes in the internal threshold of the power module 20 under high-temperature conditions, ensuring that the power module 20 can maintain a stable operating state under high-temperature conditions.

[0034] Specifically, when the ambient temperature decreases, the temperature sensing unit 120 can accurately detect the environmental change of temperature drop. Faced with a decreasing temperature, the temperature sensing unit 120 adopts the opposite adjustment strategy, reducing the output bias voltage to cope with the low-temperature environment. The reduction in bias voltage causes the voltage regulation unit 130 to receive different control signals, resulting in a corresponding increase in the on-resistance of the voltage regulation unit 130.

[0035] When the on-resistance of the voltage regulation unit 130 increases, the transmission characteristics of the circuit change, ultimately resulting in an increase in the voltage transmitted to the enable terminal of the power module 20. By increasing the enable terminal voltage, the anti-oscillation circuit 10 can adapt to the operating requirements of the power module 20 in low-temperature environments, preventing unstable operation or oscillation phenomena under low-temperature conditions.

[0036] In some embodiments of this application, a complete and efficient temperature-voltage feedback regulation system is formed among the voltage divider unit 110, the temperature sensing unit 120, and the voltage regulation unit 130. The input voltage first undergoes basic voltage processing through the voltage divider unit 110 to provide a stable voltage reference for the entire system. The temperature sensing unit 120 continuously monitors changes in ambient temperature and converts the temperature information into a corresponding bias voltage regulation signal in real time.

[0037] The voltage regulation unit 130, acting as an actuator, receives the bias voltage signal from the temperature sensing unit 120 and dynamically adjusts its own on-resistance according to the change in bias voltage. The change in on-resistance directly affects the final voltage transmitted from the voltage divider unit 110 to the enable terminal of the power module 20, thereby achieving precise control of the operating state of the power module 20.

[0038] Regardless of whether the environment is high or low, the temperature sensing unit 120 can accurately sense temperature changes and make corresponding adjustment responses. Through dynamic adjustment of the bias voltage, the voltage regulation unit 130 can adjust its own on-resistance characteristics in real time to ensure that the enable terminal of the power module 20 always receives an appropriate control voltage.

[0039] Changes in ambient temperature trigger a response from the temperature sensing unit 120. The temperature sensing unit 120 transmits temperature information to the voltage regulation unit 130 by adjusting the bias voltage. The voltage regulation unit 130 adjusts the on-resistance according to the bias voltage, which ultimately affects the enable terminal voltage, forming a complete temperature compensation closed loop.

[0040] In some embodiments of this application, a circuit schematic of an anti-oscillation circuit is provided, such as... Figure 3 As shown, the voltage divider unit 110 includes resistors R1 and R2, forming a basic resistor voltage divider network. The first end of resistor R1 is connected to the input terminal of the power supply module 20 to receive the externally supplied input voltage Vin. The second end of resistor R1 is connected to the first end of resistor R2, forming a voltage divider node, which is also electrically connected to the input terminal of the voltage regulation unit 130. The second end of resistor R2 is connected to reference ground, completing the basic structure of the voltage divider circuit.

[0041] Specifically, the series connection of resistors R1 and R2 allows the input voltage Vin to be divided according to the resistance ratio of the two resistors. The voltage at the voltage divider node is equal to the product of the input voltage Vin and the proportion of the resistance R2 in the total resistance. By selecting appropriate resistance values ​​for R1 and R2, the desired voltage division ratio can be obtained, providing a suitable voltage reference for subsequent voltage regulation.

[0042] The temperature sensing unit 120 includes a thermistor Rntc and a resistor R3, forming a temperature-sensitive bias voltage generation circuit. The first terminal of resistor R3 is connected to the input terminal of the power module 20, and together with the first terminal of resistor R1, receives the input voltage Vin. The second terminal of resistor R3 is connected to the first terminal of the thermistor Rntc, and this connection point also establishes a connection with the control terminal of the voltage regulation unit 130. The second terminal of the thermistor Rntc is connected to reference ground, sharing the same reference ground connection with the second terminal of resistor R2.

[0043] In some embodiments of this application, the physical distance between the thermistor Rntc and the power module 20 is less than or equal to 2 mm. By placing the thermistor Rntc very close to the power module 20, it is possible to ensure that the thermistor Rntc accurately senses the temperature changes generated during the operation of the power module 20. The close physical arrangement enables the thermistor Rntc to respond in real time to temperature fluctuations in the power module 20 and its surrounding environment, improving the accuracy and response speed of temperature detection.

[0044] In some embodiments of this application, the thermistor Rntc is a negative temperature coefficient thermistor, which has the characteristic that its resistance decreases as the temperature increases. When the ambient temperature rises, the resistance of the negative temperature coefficient thermistor Rntc decreases accordingly; when the ambient temperature falls, the resistance of the thermistor Rntc increases accordingly. This temperature-resistance characteristic allows the thermistor Rntc to convert changes in ambient temperature into changes in resistance, thereby affecting the voltage distribution in the circuit.

[0045] Specifically, resistor R3 and thermistor Rntc form another voltage divider network. The voltage at their junction depends on the input voltage Vin and the resistance ratio of R3 and Rntc. Since the resistance of thermistor Rntc changes with temperature, the voltage at the junction of R3 and Rntc also changes accordingly. When the temperature rises, the resistance of Rntc decreases, and the voltage at the junction increases; when the temperature decreases, the resistance of Rntc increases, and the voltage at the junction decreases.

[0046] The voltage regulation unit 130 includes a switching transistor Q1. The gate of the switching transistor Q1 is connected to the output terminal of the temperature sensing unit 120, specifically to the connection point of resistor R3 and the thermistor Rntc. Through this connection, the gate of the switching transistor Q1 can receive a bias voltage signal that varies with temperature. The drain of the switching transistor Q1 is connected to the output terminal of the voltage divider unit 110, specifically to the voltage divider node of resistors R1 and R2, for receiving the divided voltage provided by the voltage divider unit 110.

[0047] In some embodiments of this application, the source of switch Q1 is connected to the enable pin of power module 20, establishing an electrical path between voltage regulation unit 130 and the enable terminal of power module 20. Through this connection configuration, switch Q1 can control the magnitude of the voltage transmitted from the voltage divider node to the enable terminal of power module 20. Switch Q1 adjusts the on-resistance between its drain and source based on the bias voltage received at its gate, thereby affecting the final voltage transmitted to the enable terminal.

[0048] By way of example and not limitation, the gate threshold voltage of switch Q1 is less than or equal to 1.5V, ensuring that switch Q1 can achieve effective turn-on control at a lower gate voltage. The lower gate threshold voltage makes switch Q1 more sensitive to changes in the bias voltage provided by the temperature sensing unit 120, enabling a significant adjustment response in conduction characteristics even with small changes in the bias voltage. Switch Q1 is an N-channel metal-oxide-semiconductor field-effect transistor. The on-resistance of an N-channel MOSFET decreases as the gate voltage increases. When the gate voltage exceeds the threshold voltage, the MOSFET enters the turn-on state, and the resistance between the drain and source decreases significantly.

[0049] Specifically, when the ambient temperature rises, the resistance of the negative temperature coefficient thermistor Rntc decreases, leading to an increase in the voltage at the connection point between resistor R3 and the thermistor Rntc. This increase in connection point voltage causes an increase in the gate voltage of switch Q1, which in turn reduces the on-resistance of switch Q1. This decrease in the on-resistance of switch Q1 alters the voltage transfer characteristics from the voltage divider node to the enable terminal, ultimately reducing the voltage transferred to the enable terminal of power module 20.

[0050] In some embodiments of this application, when the ambient temperature decreases, the resistance of the negative temperature coefficient thermistor Rntc increases, causing a decrease in the voltage at the connection point between resistor R3 and the thermistor Rntc. This decrease in connection point voltage leads to a decrease in the gate voltage of switch Q1, which in turn increases the on-resistance of switch Q1. This increased on-resistance alters the circuit's transmission characteristics, ultimately increasing the voltage transmitted to the enable terminal of power module 20.

[0051] Unlike existing technologies, this utility model embodiment can automatically compensate for the temperature drift of the power module enable threshold under different temperature environments, effectively preventing the power module from oscillating near the undervoltage point and improving the working stability and reliability of the power module under extreme temperature environments.

[0052] Based on the anti-oscillation circuit provided in the above embodiments, this utility model also provides a power supply, which includes a power module and the anti-oscillation circuit provided in any of the above embodiments.

[0053] It should be noted that while the preferred embodiments of this utility model are provided in the specification and accompanying drawings, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this utility model; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this utility model specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An anti-oscillation circuit, characterized in that, include: Voltage divider unit, temperature sensing unit, and voltage regulation unit; The voltage divider unit is connected to the input terminal of the power module and the voltage regulation unit, the temperature sensing unit is connected to the input terminal of the power module and the voltage regulation unit, and the voltage regulation unit is also connected to the enable terminal of the power module. The voltage divider unit is used to divide the input voltage of the power module according to a preset ratio to provide a divided voltage to the voltage regulation unit; The temperature sensing unit is used to provide a bias voltage to the voltage regulation unit and also to adjust the bias voltage according to changes in ambient temperature. The voltage regulation unit is used to adjust its own on-resistance according to the bias voltage, thereby adjusting the voltage at the enable terminal of the power module.

2. The circuit of claim 1, wherein, When the ambient temperature rises, the temperature sensing unit increases the bias voltage to reduce the on-resistance of the voltage regulation unit, thereby reducing the voltage at the enable terminal of the power module. When the ambient temperature decreases, the temperature sensing unit increases the on-resistance of the voltage regulation unit by reducing the bias voltage, thereby increasing the voltage at the enable terminal of the power module.

3. The circuit of claim 1, wherein, The voltage divider unit includes resistors R1 and R2. The first end of resistor R1 is connected to the input terminal of the power supply module, the second end of resistor R1 is connected to the first end of resistor R2 and the input terminal of the voltage regulation unit, and the second end of resistor R2 is connected to reference ground.

4. The circuit of claim 1, wherein, The temperature sensing unit includes a thermistor Rntc and a resistor R3. The first end of the resistor R3 is connected to the input terminal of the power module, and the second end of the resistor R3 is connected to the first end of the thermistor Rntc and the control terminal of the voltage regulation unit. The second end of the thermistor Rntc is connected to the reference ground.

5. The circuit of claim 4, wherein, The physical distance between the thermistor Rntc and the power module is less than or equal to 2mm.

6. The circuit of claim 4, wherein, The thermistor Rntc is a negative temperature coefficient thermistor.

7. The circuit of claim 1, wherein The voltage regulation unit includes a switching transistor Q1, the gate of which is connected to the output terminal of the temperature sensing unit, the drain of which is connected to the output terminal of the voltage divider unit, and the source of which is connected to the enable pin of the power supply module.

8. The circuit of claim 7, wherein, The gate threshold voltage of the switch Q1 is less than or equal to 1.5V.

9. The circuit of claim 7, wherein, The switching transistor Q1 is an N-channel metal-oxide-semiconductor field-effect transistor.

10. A power supply, characterized by, include: Power module; as well as The anti-oscillation circuit as described in any one of claims 1-9.

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