Novel voltage stabilizing circuit

Abstract

The invention discloses a novel voltage stabilizing circuit, which is characterized in that a power supply control unit comprises a first resistor, a first current limiting resistor and a current expanding transistor, is connected between an input end and an output end and is used for improving the current output capability; the reference voltage generation unit comprises a TL431 reference voltage source and a second current-limiting resistor, and is used for generating stable reference voltage and bias current for normal work of the power supply control unit; the output voltage control unit comprises a first divider resistor and a second divider resistor, is connected between the output end and the reference voltage generation unit, and is used for adjusting the output voltage according to the reference voltage and the voltage division proportion; and the abnormal voltage processing unit comprises a discharge triode, a third current-limiting resistor and an adjusting resistor, is connected between the output end and the reference voltage generation unit, and is used for discharging the energy of the abnormal injected voltage. The technical problems that in the prior art, the current output capacity is limited, and the output voltage is raised when abnormal high voltage is injected are solved, and the stability and safety of the whole power supply are improved.

Description

Technical Field

[0001] This invention relates to the field of voltage regulator circuit technology, and specifically to a novel voltage regulator circuit. Background Technology

[0002] With the rapid development of electronic technology, voltage regulator circuits, as a core component of power electronic equipment, must meet basic electrical function indicators and relevant industry and national standards. In traditional voltage regulator circuit construction, Zener diodes, due to their non-ideal vertical reverse breakdown voltage-current curve, cannot guarantee voltage regulation accuracy under large load current variations. While voltage regulator circuits composed of operational amplifiers and Zener diodes can meet accuracy requirements, they require transistors or field-effect transistors, making debugging difficult. Voltage regulation schemes based on precision reference voltage sources, however, are the most common design in the power supply industry due to their ease of debugging, high voltage regulation accuracy, and fewer external components.

[0003] The TL431 (or similar models such as LM431, KA431, AZ431) is a three-terminal adjustable voltage regulator that integrates a 2.5V precision reference voltage source, an operational amplifier, and an output transistor. It features small size, low price, and excellent performance. The output voltage can be set arbitrarily within the range of 2.5V-36V through two resistors. The typical dynamic impedance is only 0.2Ω, the voltage reference error is ±0.4%, the load current capability is 1.0mA-100mA, and it has low temperature drift and low output noise voltage. It is widely used in constant current sources, voltage comparators, voltage monitors, overvoltage protection circuits, and DC regulated power supply circuits such as linear regulated power supplies and switching regulated power supplies.

[0004] Currently, there are two main types of voltage regulation solutions based on the TL431: one is a basic parallel voltage regulation scheme, and the other is a scheme that uses transistors to amplify current. Conventional voltage regulator circuits are mainly optimized for wide input voltage range and high anti-interference capability, but they still face challenges in practical applications. For example, the commonly used 3V voltage regulator circuit, used for clamping the DSP port of the AD sampling op-amp backend or for hardware protection reference voltage, can meet the requirements of existing solutions under normal application. However, when the op-amp malfunctions (such as an op-amp power supply abnormality causing the output voltage to be too high), the existing voltage regulator circuit has insufficient sinking current capability and cannot cope with the abnormally high voltage being injected into the output terminal. This causes the regulated output to be raised, which not only affects the stability of the power supply, but may also cause safety hazards in downstream circuits (such as damage to DSP pins, failure of hardware protection, etc.).

[0005] The existing technical solutions have obvious shortcomings: 1. Limited output current capability: The maximum cathode current (sink current) of the basic parallel voltage regulator scheme is usually 100mA. When the input-output voltage difference is large, the SOT-23 package can only withstand a limited loss, and can only withstand tens of mA in practice. It cannot directly drive high-power loads and needs to be used with an external current-boosting transistor. 2. High static power consumption: The current-limiting resistor and the TL431 itself always consume current. When the input-output voltage difference is large, the power consumption problem is prominent, making it unsuitable for low-power scenarios such as battery power supply. 3. Accuracy is affected by minimum cathode current: The TL431 requires a minimum cathode current I_ka(min) (usually 1mA) to operate normally. In order to meet the current requirements under harsh conditions, the current limiting resistor needs to be designed to be small, which further increases the useless power consumption under light load or high input voltage. 4. Slow transient response: To maintain stability, a compensation capacitor is often connected in parallel at the reference or output terminal, which reduces the loop bandwidth, slows down the load transient response, and results in a larger output voltage overshoot / undershoot. 5. Defects of the current amplification scheme: Although the scheme of using transistors to amplify the current increases the output current capability, it introduces base-emitter voltage (Vbe) temperature drift, which reduces the absolute accuracy and temperature stability of the output voltage. 6. Insufficient current sinking capability: Neither of the two solutions can effectively cope with the situation of abnormally high voltage being injected into the output terminal, which leads to the regulated output being raised, posing a safety hazard.

[0006] Therefore, there is an urgent need for a new type of voltage regulator circuit that can effectively control the output voltage under abnormally high voltage conditions, improve power supply stability and safety, and overcome the shortcomings of existing technologies. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a novel voltage regulator circuit that solves the technical problems of limited output current capability and output voltage being raised when abnormally high voltage is injected in the prior art, thereby improving the overall stability and safety of the power supply.

[0008] To solve the above-mentioned technical problems, the present invention provides a novel voltage regulator circuit, including a power control unit, a reference voltage generation unit, an output voltage control unit, and an abnormal voltage processing unit. The power control unit includes a first resistor, a first current-limiting resistor, and a current-amplifying transistor, which are connected between the input terminal and the output terminal to enhance the output current capability. The reference voltage generation unit includes a TL431 reference voltage source and a second current-limiting resistor, used to generate a stable reference voltage and a bias current for the power control unit to operate normally. The output voltage control unit includes a first voltage divider resistor and a second voltage divider resistor, which are connected between the output terminal and the reference voltage generation unit, and are used to adjust the output voltage according to the reference voltage and the voltage division ratio; The abnormal voltage processing unit includes a bleed transistor, a third current-limiting resistor, and an adjustment resistor, which are connected between the output terminal and the reference voltage generation unit to bleed the energy of abnormally injected voltage.

[0009] Furthermore, the output voltage is adjusted proportionally by the first voltage divider resistor and the second voltage divider resistor.

[0010] Furthermore, the current-amplifying transistor of the power control unit can be selected from transistors of different power according to the load current.

[0011] Furthermore, the working mechanism of the abnormal voltage processing unit is as follows: when an abnormally high voltage is injected into the output terminal of the voltage regulator circuit, the discharge transistor is turned on, and the injected energy is discharged through the third current-limiting resistor to prevent the output voltage from being raised.

[0012] Furthermore, the first resistor is positioned between the current-amplifying transistor and the voltage input.

[0013] The beneficial effects of this invention are: 1. It effectively solves the problem of voltage rise caused by abnormal voltage injection into the output terminal: By taking timely measures to control abnormal injection energy, the stability of the power supply is significantly improved, the safety hazards to the downstream circuit are reduced, and the reliability of the entire system is increased; 2. Effectively improves output current capability: Transistor current amplification is used to form a high-current reference voltage source, and transistors of different power can be selected according to the load current. 3. Maintain high accuracy across the entire load range: Ensures the TL431 operates at its best under medium / heavy load conditions, maintaining high loop gain and voltage regulation accuracy; 4. Strong transient response capability: Through an innovative transient enhancement mechanism, voltage overshoot and undershoot during load switching are effectively suppressed without sacrificing steady-state stability; 5. Low cost and easy to apply in engineering: The circuit structure of this invention is simple, requires few components, is easy to modify based on existing TL431 applications, and is also easy to integrate into the power management chip. Attached Figure Description

[0014] Figure 1 This is a system schematic diagram of the present invention.

[0015] Figure 2 This is a circuit diagram of the prior art solution of the present invention.

[0016] Figure 3 This is a circuit diagram of the prior art solution two of the present invention.

[0017] Figure 4 This is the voltage regulator circuit diagram of the present invention.

[0018] Figure 5 This is a schematic diagram of each unit of the voltage regulator circuit of the present invention.

[0019] The following are the labels in the diagram: Ra, first resistor; T1, current-amplifying transistor; Rc, first current-limiting resistor; U1, reference voltage source; Rb, second current-limiting resistor; R1, first voltage divider resistor; R2, second voltage divider resistor; T2, bleeder transistor; R3, third current-limiting resistor; R4, adjusting resistor. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0026] Reference Figures 1 to 5 As shown, an embodiment of a novel voltage regulator circuit of the present invention includes a power control unit, a reference voltage generation unit, an output voltage control unit, and an abnormal voltage processing unit. The power control unit includes a first resistor Ra, a first current-limiting resistor Rc, and a current-amplifying transistor T1, which are connected between the input terminal and the output terminal to enhance the output current capability. The reference voltage generation unit includes a reference voltage source U1 of TL431 and a second current-limiting resistor Rb, which are used to generate a stable reference voltage and a bias current for the normal operation of the power control unit. The output voltage control unit includes a first voltage divider resistor R1 and a second voltage divider resistor R2, which are connected between the output terminal and the reference voltage generation unit, and are used to adjust the output voltage according to the reference voltage and the voltage division ratio. The abnormal voltage processing unit includes a discharge transistor T2, a third current-limiting resistor R3, and an adjustment resistor R4, which are connected between the output terminal and the reference voltage generation unit to discharge the energy of abnormally injected voltage.

[0027] The output voltage is adjusted proportionally by the first voltage divider resistor R1 and the second voltage divider resistor R2; the current-amplifying transistor T1 of the power control unit can be selected with different power according to the load current; the working mechanism of the abnormal voltage processing unit is as follows: when an abnormally high voltage is injected into the output terminal of the voltage regulator circuit, the discharge transistor T2 is turned on, and the injected energy is discharged through the third current-limiting resistor R3 to prevent the output voltage from being raised; the first resistor Ra is located between the current-amplifying transistor T1 and the voltage input.

[0028] The specific explanation is as follows: Existing technical solutions are as follows Figure 2 As shown, the TL431 contains an internal 2.5V reference voltage. Therefore, when output feedback is introduced at the Vref terminal, the device can control the output voltage by shunting a wide range of current from the cathode to the anode. When the values ​​of the first voltage divider resistor R1 and the second voltage divider resistor R2 are fixed, their voltage division on the output voltage Vo introduces feedback. If the values ​​are increased, the feedback increases, and the shunting current of the TL431 also increases, thus causing the output voltage Vo to decrease. Clearly, this deep negative feedback circuit will stabilize at the reference voltage, at which point the output voltage Vo = (1 + R1 / R2) * Vref. By choosing different values ​​for the first voltage divider resistor R1 and the second voltage divider resistor R2, any output voltage from 2.5V to 36V can be obtained. In particular, when R1 = R2, Vo = 5V. If the first voltage divider resistor R1 is short-circuited and the second voltage divider resistor R2 is open-circuited, that is, the reference terminal is short-circuited to the cathode terminal, then the output voltage Vo = 2.5V (reference terminal voltage) will be generated. This is most suitable for use as a reference voltage source U1 in digital voltmeters, analog-to-digital converters, or other circuits. It is important to note that when selecting resistors, the necessary condition for the TL431 to operate must be ensured: the current through the cathode must be greater than 1mA. The first voltage divider resistor R1 and the second voltage divider resistor R2 must be selected from similar resistors with an accuracy of at least 1% to guarantee the long-term stability of the reference power supply.

[0029] Existing technical solution two, such as Figure 3 As shown, based on Scheme 1, a slight improvement is made by adding a current-expanding transistor T1 to enhance the output current capability. For the series regulator application shown, a compensation capacitor C1 is generally added between the cathode and the reference terminal to improve the stability of the output voltage; at this time, the output voltage Vo = (1 + R1 / R2) * Vref + Iref * R1. The value of the second current-limiting resistor Rb should meet the following two requirements: 1. The maximum value of the second current-limiting resistor Rb should ensure that the cathode current (Ik) is greater than the minimum operating current (0.5mA) under the minimum input voltage Vin_min; 2. The minimum value of the second current-limiting resistor Rb should ensure that the cathode current (Ik) does not exceed 100mA under all load conditions and the instantaneous on-state current (Ik) does not exceed 120mA.

[0030] The voltage regulator circuit of this invention is as follows: Figure 4 As shown, a current-boosting transistor T1 and a first resistor Ra are added to the conventional voltage regulator circuit to enhance the output current capability; a bleeder transistor T2, a third current-limiting resistor R3, and an adjusting resistor R4 are added to handle abnormal high voltage conditions.

[0031] For example, in practical applications, especially in the fields of power electronics and switching power supplies, voltage regulator circuits face even greater challenges. Take the commonly used 3V voltage regulator circuit, for instance. 3V is typically used as a clamping voltage at the input of the AD sampling op-amp backend to the DSP port, or as a reference voltage for hardware protection. When the op-amp output is used as the clamping voltage, if the op-amp is damaged, or if the -15V voltage in the ±15V power supply to the op-amp is short-circuited or pulled down to -2V, the op-amp output will be +15V high. In this case, +15V will be injected into the clamping voltage 3V (i.e., the output of the voltage regulator circuit) through the clamping diode. Existing voltage regulator circuits will be unable to stabilize the output voltage under these circumstances, thus raising the output 3V. However, in this invention, when similar situations occur, such as +15V being injected into the output of the voltage regulator circuit, the discharge transistor T2 conducts, dissipating the injected energy and maintaining a stable output 3V. This clamps the DSP pin potential within a tolerable range, preventing damage to the DSP or the hardware protection reference voltage 3V from rising and failing to provide protection. It improves the stability of the power supply, eliminates potential safety hazards to downstream circuits, and enhances the reliability of the system.

[0032] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A novel voltage regulator circuit, characterized in that, It includes a power control unit, a reference voltage generation unit, an output voltage control unit, and an abnormal voltage processing unit; The power control unit includes a first resistor (Ra), a first current-limiting resistor (Rc), and a current-amplifying transistor (T1), which are connected between the input and output terminals to enhance the output current capability. The reference voltage generation unit includes a reference voltage source (U1) of TL431 and a second current-limiting resistor (Rb) for generating a stable reference voltage and bias current for the normal operation of the power control unit. The output voltage control unit includes a first voltage divider resistor (R1) and a second voltage divider resistor (R2), which are connected between the output terminal and the reference voltage generation unit, and are used to adjust the output voltage according to the reference voltage and the voltage division ratio. The abnormal voltage processing unit includes a bleed transistor (T2), a third current-limiting resistor (R3), and an adjusting resistor (R4), which are connected between the output terminal and the reference voltage generation unit to bleed the energy of abnormally injected voltage.

2. The novel voltage regulator circuit according to claim 1, characterized in that, The output voltage is adjusted proportionally by the first voltage divider resistor (R1) and the second voltage divider resistor (R2).

3. The novel voltage regulator circuit according to claim 1, characterized in that, The current-amplifying transistor (T1) of the power control unit can be selected with different power transistors according to the load current.

4. The novel voltage regulator circuit according to claim 1, characterized in that, The working mechanism of the abnormal voltage processing unit is as follows: when an abnormally high voltage is injected into the output terminal of the voltage regulator circuit, the discharge transistor (T2) is turned on, and the injected energy is discharged through the third current limiting resistor (R3) to prevent the output voltage from being raised.

5. The novel voltage regulator circuit according to claim 1, characterized in that, The first resistor (Ra) is located between the current-amplifying transistor (T1) and the voltage input.

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