Voltage reference circuit and method of generating a reference voltage

Abstract

The application discloses a voltage reference circuit and a method for generating a reference voltage. The voltage reference circuit comprises a voltage dividing resistor, a first switch tube, a temperature sensing element, a microcontroller and a resistance compensation network. The voltage dividing resistor and the first switch tube are connected between a power supply voltage and a reference voltage output terminal. The temperature sensing element is used to obtain a current ambient temperature. The microcontroller is used to obtain a compensation resistance corresponding to the current ambient temperature based on a temperature-resistance value curve and a voltage dividing relationship. The resistance compensation network is controlled by the microcontroller to provide the corresponding compensation resistance, thereby improving the suppression capability of the voltage reference circuit to temperature fluctuations and ensuring that a constant reference voltage can be generated at different temperatures.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and more specifically, to a voltage reference circuit and a method for generating a reference voltage. Background Technology

[0002] Voltage reference circuits are widely used in A / D converters, D / A converters, memory and power converters to provide them with a precise and stable voltage reference. As a key unit of integrated circuits, its accuracy plays a very important role in the overall performance of the circuit.

[0003] In existing technologies, resistor voltage dividers are commonly used to obtain a fixed voltage reference. However, the resistance value is easily affected by temperature, resulting in temperature drift in voltage references obtained through resistor voltage dividers under high and low temperature environments. Furthermore, this type of voltage reference circuit is also easily affected by the power supply voltage; a sudden increase in the power supply voltage will also cause a sudden increase in the reference voltage, potentially damaging subsequent circuitry. Summary of the Invention

[0004] In view of the above problems, the purpose of this invention is to provide a voltage reference circuit and a method for generating a reference voltage, which effectively improves the problem of insufficient suppression of temperature and power supply fluctuations in existing voltage reference circuits.

[0005] According to one aspect of the present invention, a voltage reference circuit is provided, comprising: a voltage divider resistor and a first switching transistor connected between a power supply voltage and a reference voltage output terminal; a temperature sensing element for obtaining the current ambient temperature; a microcontroller for obtaining a compensation resistor corresponding to the current ambient temperature based on a temperature-resistance curve and a voltage divider relationship; and a resistance compensation network connected to the reference voltage output terminal, wherein the resistance compensation network is controlled by the microcontroller to provide a corresponding compensation resistor to achieve a constant reference voltage.

[0006] Optionally, the resistance compensation network includes: multiple compensating sub-resistors and switches, with each switch corresponding to one of the multiple compensating sub-resistors. The first terminals of the multiple switches are coupled to the reference voltage output terminal, and the second terminals of the multiple switches are grounded via the corresponding compensating sub-resistors. The multiple switches are controlled by the microcontroller to turn on and off to provide the compensation resistance.

[0007] Optionally, the voltage reference circuit further includes an overvoltage protection module, used to obtain a sampled voltage of the power supply voltage, compare the sampled voltage with a threshold voltage, and turn off the first switching transistor when the sampled voltage is lower than the threshold voltage.

[0008] Optionally, the microcontroller pre-stores multiple sets of temperature-resistance curves corresponding to the voltage divider resistor, the first switching transistor, and the plurality of compensating sub-resistors.

[0009] Optionally, the overvoltage protection module includes: an error amplifier, whose two input terminals are respectively connected to the two ends of the voltage divider resistor, and whose output terminal is used to output the sampled voltage; and a comparator, whose non-inverting input terminal is used to receive the sampled voltage, whose inverting input terminal is used to receive the threshold voltage, and whose output terminal is connected to the control terminal of the first switching transistor to control the turning on and off of the first switching transistor.

[0010] According to another aspect of the present invention, a method for generating a reference voltage is provided, comprising: obtaining the current ambient temperature; obtaining a compensation resistor corresponding to the current ambient temperature based on a temperature-resistance curve and a voltage divider relationship; controlling a resistor compensation network to provide a corresponding compensation resistor; and using a voltage divider resistor, a first switching transistor, and the compensation resistor provided by the resistor compensation network to divide the power supply voltage to obtain a constant reference voltage.

[0011] Optionally, the resistor compensation network includes multiple compensating sub-resistors and switches, with each switch corresponding to one of the multiple compensating sub-resistors. The first terminals of the multiple switches are coupled to the reference voltage output terminal, and the second terminals of the multiple switches are grounded via the corresponding compensating sub-resistors. The control resistor compensation network provides the corresponding compensation resistor by controlling the multiple switches to turn on and off to generate the corresponding compensation resistor.

[0012] Optionally, the method further includes: obtaining a sampled voltage of the power supply voltage; comparing the sampled voltage with a threshold voltage; and turning off the first switch when the sampled voltage is lower than the threshold voltage.

[0013] Optionally, the method further includes: measuring the actual resistance values ​​of the voltage divider resistor, the first switching transistor, and the plurality of compensating sub-resistors at different temperatures, and fitting multiple sets of temperature-resistance curves based on the obtained actual resistance values.

[0014] In the voltage reference circuit and method for generating a reference voltage according to embodiments of the present invention, the voltage reference circuit includes a voltage divider resistor, a first switching transistor, a temperature sensing element, a microcontroller, and a resistor compensation network. The voltage divider resistor and the first switching transistor are connected between the power supply voltage and the reference voltage output terminal. The temperature sensing element is used to obtain the current ambient temperature. The microcontroller is used to obtain the compensation resistor corresponding to the current ambient temperature based on the temperature-resistance curve and the voltage divider relationship. The resistor compensation network is controlled by the microcontroller to provide the corresponding compensation resistor, thereby improving the voltage reference circuit's ability to suppress temperature fluctuations and ensuring that a constant reference voltage can be generated at different temperatures.

[0015] Furthermore, the voltage reference circuit in this embodiment also includes an overvoltage protection module. The overvoltage protection module is used to obtain a sample voltage of the power supply voltage, compare the sample voltage with a threshold voltage, and turn off the first switch when the sample voltage is less than the threshold voltage, thereby disconnecting the power supply voltage from the subsequent circuit when the power supply voltage fluctuates, and improving the circuit's ability to suppress power supply fluctuations. Attached Figure Description

[0016] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A schematic circuit diagram of a voltage reference circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0018] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0019] It should be understood that, in the following description, "circuit" may include single or combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by the programmable circuit. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it may be directly coupled or connected to the other element, or there may be intermediate elements; the connection between elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 A schematic circuit diagram of a voltage reference circuit according to an embodiment of the present invention is shown. Figure 1 As shown, the voltage reference circuit 100 in this embodiment includes a voltage divider resistor R1, a switching transistor M1, a resistor compensation network 110, a temperature sensing element 120, and a microcontroller 130.

[0022] In this circuit, the voltage divider resistor R1 and the switching transistor M1 are connected between the output terminals of the power supply voltage Vcc and the reference voltage Vref. The resistor compensation network 110 is connected to the output terminal of the reference voltage Vref and provides compensation resistance to ensure that the reference voltage Vref remains constant under different temperatures. The specific implementation process is as follows: the current ambient temperature is obtained through the temperature sensing element 120. Then, the microcontroller 130 calculates the actual required resistance value at the current temperature based on the temperature-resistance curve, the voltage divider relationship, the fixed power supply voltage Vcc, and the desired reference voltage Vref. Then, based on the actual required resistance value, the compensation resistor corresponding to the current ambient temperature is obtained, and the resistor compensation network 110 is controlled to provide this compensation resistor to the output terminal of the reference voltage.

[0023] Optionally, the resistance compensation network 110 includes multiple compensation sub-resistors and switches, which correspond one-to-one, for example, in... Figure 1 In the example, the resistor compensation network 110 includes five compensating sub-resistors R21-R25 and five switches K1-K5. The first terminal of each switch K1-K5 is coupled to the output of the reference voltage Vref, and the second terminal is grounded via the corresponding compensating sub-resistor. After the microcontroller 130 calculates the resistance value to be compensated, it controls the corresponding switch to turn on, thereby combining in the resistor compensation network 110 to generate the required compensation resistance. It can be understood that the number of compensating sub-resistors in the resistor compensation network 110 is not fixed. Figure 1 The embodiments described herein are limitations, and those skilled in the art can configure any number of compensating sub-resistors and switches as needed.

[0024] Optionally, multiple sets of temperature-resistance curves can be pre-stored in the microcontroller 130. The actual resistance values ​​of the voltage divider resistor R1, the switching transistor M1, and the multiple compensating sub-resistors R21-R25 can be measured at different temperatures. Then, based on the obtained actual resistance values, multiple sets of temperature-resistance curves corresponding to the voltage divider resistor R1, the switching transistor M1, and the multiple compensating sub-resistors R21-R25 can be fitted and stored in the microcontroller 130.

[0025] Furthermore, traditional voltage reference circuits have poor ability to suppress power supply fluctuations. When the power supply voltage Vcc fluctuates drastically, it can cause the reference voltage Vref to suddenly increase, damaging subsequent circuits. To solve this problem, the voltage reference circuit 100 in this embodiment also includes an overvoltage protection module 140. The overvoltage protection module 140 is used to obtain a sampled voltage of the power supply voltage Vcc, compare the sampled voltage with a threshold voltage Vth, and turn off the switching transistor M1 when the sampled voltage is lower than the threshold voltage Vth.

[0026] Optionally, the overvoltage protection module 140 includes an error amplifier EA and a comparator comp1. The two input terminals of the error amplifier EA are respectively connected to the two ends of the voltage divider resistor R1, and the output terminal is used to output the sampled voltage. The non-inverting input terminal of the comparator comp1 is used to receive the sampled voltage, and the inverting input terminal is used to receive the threshold voltage Vth. The output terminal is connected to the control terminal of the switching transistor M1 to control the switching transistor M1 to turn on and off. When the sampled voltage is lower than the threshold voltage Vth, the comparator comp1 outputs a logic low level, turns off the switching transistor M1, and disconnects the power supply voltage Vcc from the subsequent circuit, thereby realizing overvoltage protection.

[0027] In summary, in the voltage reference circuit and the method for generating a reference voltage according to the embodiments of the present invention, the voltage reference circuit includes a voltage divider resistor, a first switching transistor, a temperature sensing element, a microcontroller, and a resistor compensation network. The voltage divider resistor and the first switching transistor are connected between the power supply voltage and the reference voltage output terminal. The temperature sensing element is used to obtain the current ambient temperature. The microcontroller is used to obtain the compensation resistor corresponding to the current ambient temperature based on the temperature-resistance curve and the voltage divider relationship. The resistor compensation network is controlled by the microcontroller to provide the corresponding compensation resistor, thereby improving the voltage reference circuit's ability to suppress temperature fluctuations and ensuring that a constant reference voltage can be generated at different temperatures.

[0028] Furthermore, the voltage reference circuit in this embodiment also includes an overvoltage protection module. The overvoltage protection module is used to obtain a sample voltage of the power supply voltage, compare the sample voltage with a threshold voltage, and turn off the first switch when the sample voltage is less than the threshold voltage, thereby disconnecting the power supply voltage from the subsequent circuit when the power supply voltage fluctuates, and improving the circuit's ability to suppress power supply fluctuations.

[0029] It should be noted that although devices are described herein as N-channel or P-channel devices, or N-type or P-type doped regions, those skilled in the art will understand that complementary devices are also possible according to the present invention. Those skilled in the art will understand that conductivity type refers to the mechanism by which conductivity occurs, such as conduction through holes or electrons; therefore, conductivity type relates to doping type, such as P-type or N-type, rather than doping concentration. Those skilled in the art will understand that the terms “during,” “when,” and “when…” used herein in relation to circuit operation are not strict terms indicating an action that occurs immediately at the start of a startup action, but rather that there may be one or more small but reasonable delays between the startup action and the reaction action initiated by it, such as various propagation delays. The terms “approximately” or “substantially” used herein mean that an element value has a parameter expected to be close to the declared value or location. However, as is well known in the art, there are always small deviations that make it difficult for the value or location to be strictly the declared value. It has been properly determined in the art that a deviation of at least 10 percent (10%) (or at least 20 percent (20%) for semiconductor doping concentration) is a reasonable deviation from the described accurate ideal target. When used in conjunction with signal states, the actual voltage value or logic state of the signal (e.g., "1" or "0") depends on whether positive or negative logic is used.

[0030] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0031] As described above, these embodiments of the present invention do not exhaustively describe all details, nor do they limit the invention to specific embodiments. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The scope of protection of this invention should be determined by the scope defined in the claims of this invention.

Claims

1. A voltage reference circuit, comprising: A voltage divider resistor and a first switching transistor are connected between the power supply voltage and the reference voltage output terminals; Temperature sensing element, used to obtain the current ambient temperature; A microcontroller is used to obtain the compensation resistor corresponding to the current ambient temperature based on the temperature-resistance curve and voltage division relationship; as well as A resistor compensation network is connected to the output terminal of the reference voltage. The resistor compensation network is controlled by the microcontroller to provide corresponding compensation resistors to achieve a constant reference voltage.

2. The voltage reference circuit according to claim 1, wherein, The resistance compensation network includes: The system includes multiple compensating resistors and switches, with each switch corresponding to one of the multiple compensating resistors. The first terminal of each switch is coupled to the reference voltage output terminal, and the second terminal of each switch is grounded via its corresponding compensating resistor. The plurality of switches are controlled by the microcontroller to turn on and off in order to provide the compensation resistor.

3. The voltage reference circuit according to claim 1, further comprising: An overvoltage protection module is used to obtain a sampled voltage of the power supply voltage, compare the sampled voltage with a threshold voltage, and turn off the first switching transistor when the sampled voltage is lower than the threshold voltage.

4. The voltage reference circuit according to claim 2, wherein, The microcontroller has pre-stored multiple sets of temperature-resistance curves corresponding to the voltage divider resistor, the first switching transistor, and the multiple compensating sub-resistors.

5. The voltage reference circuit according to claim 3, wherein, The overvoltage protection module includes: An error amplifier, whose two input terminals are respectively connected to the two ends of the voltage divider resistor, and whose output terminal is used to output the sampled voltage; and The comparator has a non-inverting input terminal for receiving the sampled voltage, an inverting input terminal for receiving the threshold voltage, and an output terminal connected to the control terminal of the first switch to control the turn-on and turn-off of the first switch.

6. A method for generating a reference voltage, comprising: Obtain the current ambient temperature; The compensation resistor corresponding to the current ambient temperature is obtained based on the temperature-resistance curve and the voltage divider relationship. The control resistor compensation network provides the corresponding compensation resistors; and The power supply voltage is divided using voltage divider resistors, a first switching transistor, and compensation resistors provided by the resistor compensation network to obtain a constant reference voltage.

7. The method according to claim 6, wherein, The resistance compensation network includes multiple compensating sub-resistors and switches, with each switch corresponding to one of the multiple compensating sub-resistors. The first terminals of the multiple switches are coupled to the output terminal of the reference voltage, and the second terminals of the multiple switches are grounded via their corresponding compensating sub-resistors. The control resistor compensation network provides corresponding compensation resistors, including: Controlling the multiple switches to turn them on and off generates the corresponding compensation resistors.

8. The method according to claim 6, wherein, Also includes: Obtain the sampled voltage of the power supply voltage; The sampled voltage is compared with the threshold voltage; as well as The first switch is turned off when the sampled voltage is lower than the threshold voltage.

9. The method according to claim 7, wherein, Also includes: The actual resistance values ​​of the voltage divider resistor, the first switching transistor, and the plurality of compensating sub-resistors are measured at different temperatures, and multiple sets of temperature-resistance curves are obtained by fitting the obtained actual resistance values.

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