CN115225044A - Protection circuit and display screen that rail-to-rail output fortune was put - Google Patents

Protection circuit and display screen that rail-to-rail output fortune was put Download PDF

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Publication number
CN115225044A
CN115225044A CN202211077922.3A CN202211077922A CN115225044A CN 115225044 A CN115225044 A CN 115225044A CN 202211077922 A CN202211077922 A CN 202211077922A CN 115225044 A CN115225044 A CN 115225044A
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China
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output
tube
switching tube
rail
controlled
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CN202211077922.3A
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CN115225044B (en
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陈小平
戴兴科
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Shenzhen Weiyuan Semiconductor Co ltd
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Shenzhen Weiyuan Semiconductor Co ltd
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/52—Circuit arrangements for protecting such amplifiers
    • H03F1/523—Circuit arrangements for protecting such amplifiers for amplifiers using field-effect devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit

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  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

The application is suitable for the technical field of operational amplifiers, and provides a rail-to-rail output operational amplifier protection circuit and a display screen, wherein a first current value flowing through a first output tube is detected by a first detection unit, a first power clamping unit is controlled to be connected with a passage between a controlled end of the first output tube and a power supply when a first voltage value corresponding to the first current value is greater than a reference voltage value by a first comparison unit, and the current value flowing through the first output tube is clamped at a preset current threshold value by the first current clamping unit; the second current value flowing through the second output tube is detected through the second detection unit, the second power clamping unit is controlled to be connected with a passage between the controlled end of the second output tube and the ground through the second comparator when the second voltage value corresponding to the second current value is larger than the reference voltage value, and the current value flowing through the second output tube is clamped at the preset current threshold through the second current clamping unit, so that the operational amplifier is ensured to have large output current capability, and reliable short-circuit protection can be carried out on the operational amplifier.

Description

Protection circuit and display screen that rail-to-rail output fortune was put
Technical Field
The application belongs to the technical field of operational amplifiers, and particularly relates to a rail-to-rail output operational amplifier protection circuit and a display screen.
Background
A Rail-to-Rail (Rail-to-Rail) output operational amplifier is one kind of operational amplifier, and since the output voltage of the operational amplifier is allowed to vary between a positive power supply voltage and a negative power supply voltage, that is, when the output voltage of the Rail-to-Rail output operational amplifier reaches the upper and lower limits of the power supply voltage, the Rail-to-Rail output operational amplifier is not saturated or inverted as a conventional operational amplifier, the Rail-to-Rail output operational amplifier is widely applied in a high-voltage high-power scene.
The high-power rail-to-rail output operational amplifier has a large output current capability, so that an output circuit of the high-power rail-to-rail output operational amplifier is easy to generate a short circuit to the ground or a short circuit to a power supply, and a short-circuit protection circuit is generally required to be designed to perform short-circuit protection on the output circuit of the high-power rail-to-rail output operational amplifier in order to avoid burning of the high-power rail-to-rail output operational amplifier when the output circuit of the high-power rail-to-rail output operational amplifier is short-circuited. The conventional short-circuit protection circuit is used for switching off an output tube in an output circuit when the output current exceeds a preset current threshold value by detecting the output current of a high-power rail-to-rail output operational amplifier so as to switch off the output circuit, thereby realizing the short-circuit protection of the output circuit.
However, if the power supply voltage is large, the output tube of the rail-to-rail output op-amp will be subjected to a large amount of power in case of a short circuit of the output circuit to the power supply, which may result in thermal burnout of the rail-to-rail output op-amp in a very short time. And if the preset current threshold value is reduced, the output current capability of the rail-to-rail output operational amplifier during normal operation can be reduced. Therefore, the conventional short-circuit protection circuit of the rail-to-rail output operational amplifier cannot simultaneously ensure that the rail-to-rail output operational amplifier has larger output current capability and can realize reliable protection of an output circuit under the condition of larger power supply voltage.
Disclosure of Invention
In view of this, embodiments of the present application provide a protection circuit and a display screen for a rail-to-rail output operational amplifier, so as to solve the technical problem that the conventional short-circuit protection circuit for a high-power rail-to-rail output operational amplifier cannot simultaneously ensure that the rail-to-rail output operational amplifier has a relatively large output current capability and can reliably protect an output circuit.
In a first aspect, an embodiment of the present application provides a protection circuit of a rail-to-rail output operational amplifier, which is connected to an output circuit of the rail-to-rail output operational amplifier; the output circuit comprises a first output tube connected between a power supply and the output end of the rail-to-rail output operational amplifier and a second output tube connected between the output end and the ground; the protection circuit comprises a first detection unit, a first comparison unit, a first power clamping unit, a first current clamping unit, a second detection unit, a second comparison unit, a second power clamping unit and a second current clamping unit;
the first detection unit is connected between the power supply and the output end, the first power clamping unit and the first current clamping unit are both connected between the power supply and the controlled end of the first output tube, the input end and the output end of the first detection unit are also respectively connected with the controlled end of the first output tube and the positive input end of the first comparison unit, and the output end of the first comparison unit is connected with the controlled end of the first power clamping unit; the second detection unit is connected between the output end of the rail-to-rail output operational amplifier and the ground, the second power clamping unit and the second current clamping unit are both connected between the controlled end of the second output tube and the ground, the input end and the output end of the second detection unit are also respectively connected with the controlled end of the second output tube and the positive input end of the second comparison unit, and the output end of the second comparison unit is connected with the controlled end of the second power clamping unit;
the first detection unit is used for detecting a first current value flowing through the first output tube and outputting a first voltage signal corresponding to the first current value; the first comparison unit is used for determining that the power of the first output tube is greater than a preset power threshold value and outputting a first control signal when the voltage value of the first voltage signal is greater than a reference voltage value; the first power clamping unit is used for switching on a path between the controlled end of the first output tube and the power supply based on the first control signal; the first current clamping unit is used for clamping the first current value flowing through the first output tube at a preset current threshold value;
the second detection unit is used for detecting a second current value flowing through the second output tube and outputting a second voltage signal corresponding to the second current value; the second comparing unit is used for determining that the power of the second output tube is greater than the preset power threshold value and outputting a second control signal when the voltage value of the second voltage signal is greater than the reference voltage value; the second power clamping unit is used for switching on a path between the controlled end of the second output tube and the ground based on the second control signal; the second current clamping unit is used for clamping the second current value flowing through the second output tube at a preset current threshold value.
In an optional implementation manner of the first aspect, the first detection unit includes a first switch tube and a first resistor; the first end of first resistance is connected the power, the second end of first resistance is connected the first switch-on end of first switch tube, the second switch-on end of first switch tube is connected the output that rail-to-rail output fortune was put, the controlled end of first switch tube is the input of first detecting element, the second end of first resistance is the output of first detecting element.
In an optional implementation manner of the first aspect, the first power clamp unit includes a second switching tube and a third switching tube; the first conduction end of the second switch tube is connected with the power supply, the second conduction end of the second switch tube is connected with the first conduction end of the third switch tube, the controlled end and the second conduction end of the third switch tube are connected to the controlled end of the first output tube, and the controlled end of the second switch tube is the controlled end of the first power clamping unit.
In an optional implementation manner of the first aspect, the first current clamp unit includes a fourth switching tube, a fifth switching tube, and a sixth switching tube; the first switch-on end of fourth switch tube is connected the power, the controlled end of fourth switch tube with the second switch-on end of fourth switch tube connects in the first switch-on end of fifth switch tube altogether, the controlled end of fifth switch tube with the second switch-on end of fifth switch tube connects in the first switch-on end of sixth switch tube altogether, the controlled end of sixth switch tube with the second switch-on end of sixth switch tube connects in the controlled end of first output tube altogether.
In an optional implementation manner of the first aspect, the second detection unit includes a seventh switch tube and a second resistor; the first conduction end of the seventh switch tube is connected with the output end of the rail-to-rail output operational amplifier, the second conduction end of the seventh switch tube is connected with the first end of the second resistor, the second end of the second resistor is grounded, the controlled end of the seventh switch tube is the input end of the second detection unit, and the first end of the second resistor is the output end of the second detection unit.
In an optional implementation manner of the first aspect, the second power clamp unit includes an eighth switching tube and a ninth switching tube; the first conducting end and the controlled end of the eighth switching tube are commonly connected to the controlled end of the second output tube, the second conducting end of the eighth switching tube is connected to the first conducting end of the ninth switching tube, the second conducting end of the ninth switching tube is grounded, and the controlled end of the ninth switching tube is used as the controlled end of the second power clamping unit.
In an optional implementation manner of the first aspect, the second current clamping unit includes a tenth switching tube, an eleventh switching tube, and a twelfth switching tube; the first conducting end and the controlled end of the tenth switching tube are connected to the controlled end of the second output tube, the first conducting end and the controlled end of the eleventh switching tube are connected to the second conducting end of the tenth switching tube, the first conducting end and the controlled end of the twelfth switching tube are connected to the second conducting end of the eleventh switching tube, and the second conducting end of the twelfth switching tube is grounded.
In an optional implementation manner of the first aspect, the protection circuit further includes a reference voltage generating unit; the input end of the reference voltage generating unit is connected with the output end of the rail-to-rail output operational amplifier, the power supply end of the reference voltage generating unit is connected with the power supply, the ground end of the reference voltage generating unit is grounded, and the output end of the reference voltage generating unit is connected with the negative input end of the first comparing unit and the negative input end of the second comparing unit;
the reference voltage generating unit is used for generating a reference voltage signal; the voltage value of the reference voltage signal is the reference voltage value.
In an optional implementation manner of the first aspect, the reference voltage generating unit includes a reference current generating unit and a third resistor; a first end of the reference current generating unit is used as an input end of the reference voltage generating unit, a second end of the reference current generating unit is used as a power supply end of the reference voltage generating unit, a third end of the reference current generating unit and a first end of the third resistor are connected in common to serve as an output end of the reference voltage generating unit, and a fourth end of the reference current generating unit and a second end of the third resistor are connected in common to serve as a ground end of the reference voltage generating unit;
the reference current generating unit comprises a first operational amplifier, a thirteenth switching tube, a fourth resistor, a fourteenth switching tube, a fifteenth switching tube, a sixteenth switching tube, a seventeenth switching tube, an eighteenth switching tube, a nineteenth switching tube, a twentieth switching tube, a twenty-first switching tube, a twenty-second switching tube, a twentieth switching tube, a first current source and a second current source; a non-inverting input terminal of the first operational amplifier is used as a first terminal of the reference current generating unit, an inverting input terminal of the first operational amplifier and a first terminal of the fourth resistor are commonly connected to a first conducting terminal of the thirteenth switching tube, an output terminal of the first operational amplifier is connected to a controlled terminal of the thirteenth switching tube, a second conducting terminal of the thirteenth switching tube, a first conducting terminal of the fourteenth switching tube and a controlled terminal of the fourteenth switching tube are commonly connected to a controlled terminal of the fifteenth switching tube, a first conducting terminal of the sixteenth switching tube, a controlled terminal of the sixteenth switching tube and a controlled terminal of the seventeenth switching tube are commonly connected to a first conducting terminal of the fifteenth switching tube, a first conducting terminal of the seventeenth switching tube and a first conducting terminal of the eighteenth switching tube are commonly connected to a controlled terminal of the nineteenth switch, the first conducting end of the nineteenth switch, the first conducting end of the twentieth switch tube and the controlled end of the twentieth switch tube are connected to the controlled end of the twenty-first switch tube, the controlled end of the eighteenth switch tube, the output end of the first current source and the first conducting end of the twenty-second switch tube are connected to the controlled end of the twenty-second switch tube, the controlled end of the twenty-second switch tube and the first conducting end of the twentieth switch tube are connected to the input end of the second current source, the second end of the fourth resistor, the second conducting end of the sixteenth switch tube, the second conducting end of the seventeenth switch tube, the second conducting end of the nineteenth switch, the second conducting end of the twenty-second switch tube and the output end of the second current source are all grounded, and the second conducting end of the fourteenth switch tube, the first conducting end of the twentieth switch tube and the second conducting end of the second current source are all grounded, the second conduction end of the fifteenth switch tube, the second conduction end of the eighteenth switch tube, the second conduction end of the twentieth switch tube, the input end of the first current source, the second conduction end of the twentieth switch tube and the second conduction end of the twenty-first switch tube are all connected with the power supply.
In a second aspect, an embodiment of the present application provides a display screen, including a rail-to-rail output operational amplifier and a protection circuit as described in the first aspect or any optional implementation manner of the first aspect, where the protection circuit is connected to the rail-to-rail output operational amplifier.
The rail-to-rail output operational amplifier protection circuit and the display screen have the following beneficial effects:
the protection circuit for rail-to-rail output operational amplifier provided by the embodiment of the application, by arranging the first detection unit between the power supply and the output end of the rail-to-rail output operational amplifier, by arranging the first power clamping unit and the first current clamping unit between the power supply and the controlled end of the first output tube, by connecting the input end and the output end of the first detection unit with the controlled end of the first output tube and the positive input end of the first comparison unit respectively, and by connecting the output end of the first comparison unit with the controlled end of the first power clamping unit, the first detection unit detects a first current value flowing through the first output tube, and outputs a first voltage signal corresponding to the first current value, so that the first comparison unit determines that the power of the first output tube is greater than a preset power threshold value when the voltage value of the first voltage signal is greater than a reference voltage value, and outputs the first control signal, so that the first power clamping unit switches on a path between the controlled end of the first output tube and the power supply based on the first control signal, thereby reducing the current value flowing through the first output tube, and enabling the first power clamping unit to output the first output tube to output the rail-to output power output tube when the first output current is greater than the preset power threshold value, thereby enabling the first power clamping unit to achieve the normal operation of the rail-to avoid the first output operational amplifier, and further to avoid the first output power output tube, and to avoid the first output power clamping unit, and to damage the first output tube when the first output tube, and the first output power clamping unit.
Similarly, by arranging the second detection unit between the output end of the rail-to-rail output operational amplifier and the ground, by arranging the second power clamping unit and the second current clamping unit between the controlled end of the second output tube and the ground, by respectively connecting the input end and the output end of the second detection unit with the controlled end of the second output tube and the positive input end of the second comparison unit, and by connecting the output end of the second comparison unit with the controlled end of the second power clamping unit, the second detection unit detects the second current value flowing through the second output tube and outputs the second voltage signal corresponding to the second current value, so that the second comparison unit determines that the power of the second output tube is greater than the preset power threshold value when the voltage value of the second voltage signal is greater than the reference voltage value, and outputting a second control signal to enable the second power clamping unit to be connected with a passage between the controlled end of the second output tube and the ground based on the second control signal, so as to reduce the current value flowing through the second output tube and further reduce the power of the second output tube, and enable the second current clamping unit to clamp the second current value flowing through the second output tube at a preset current threshold value when the rail-to-rail output operational amplifier normally works, so that the rail-to-rail output operational amplifier can be ensured to have larger output current capability when normally works, and the power of the second output tube can be reduced when the power of the second output tube is larger than the preset power threshold value due to the power short circuit of the output circuit to the power supply, thereby avoiding the second output end from being burnt, and realizing reliable short circuit protection of the second output tube.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a short-circuit protection circuit of an output circuit of a conventional high-power rail-to-rail output operational amplifier;
fig. 2 is a schematic structural diagram of a protection circuit of a rail-to-rail output operational amplifier according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a protection circuit of a rail-to-rail output operational amplifier according to another embodiment of the present disclosure;
fig. 4 is a schematic circuit diagram of a protection circuit of a rail-to-rail output operational amplifier according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a display screen provided in an embodiment of the present application.
Detailed Description
It is to be understood that the terminology used in the embodiments of the present application is for the purpose of describing particular embodiments of the present application only and is not intended to be limiting of the application. In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a definition of "a first" or "a second" feature may explicitly or implicitly include one or more of the features. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically stated.
Because the high-power rail-to-rail output operational amplifier has a large output current capability, an output circuit of the high-power rail-to-rail output operational amplifier is easy to generate a short circuit to the ground or a short circuit to a power supply, and in order to avoid that the high-power rail-to-rail output operational amplifier is burnt when the output circuit of the high-power rail-to-rail output operational amplifier is short-circuited, a short-circuit protection circuit is generally required to be designed to perform short-circuit protection on the output circuit of the high-power rail-to-rail output operational amplifier. The conventional short-circuit protection circuit is used for switching off an output tube in an output circuit when the output current exceeds a preset current threshold value by detecting the output current of a high-power rail-to-rail output operational amplifier so as to switch off the output circuit, thereby realizing the short-circuit protection of the output circuit.
As shown in fig. 1, the exemplary embodiment is a schematic structural diagram of a short-circuit protection circuit of an output circuit of a conventional high-power rail-to-rail output operational amplifier. The short-circuit protection circuit comprises a first protection circuit and a second protection circuit, wherein the first protection circuit is used for performing short-circuit protection on an upper tube M1 'of an output circuit, the second protection circuit is used for performing short-circuit protection on a lower tube M2' of the output circuit, the first protection circuit comprises a switching tube Q1 'and a switching tube Q2' which are connected between a power supply and a controlled end of the upper tube M1', and the second protection circuit comprises a switching tube Q3' and a switching tube Q4 'which are connected between a controlled end of the lower tube M2' and the ground. The conventional short-circuit protection circuit performs short-circuit protection on an output circuit based on a fixed current value. Specifically, for example, when the output circuit is short-circuited to the power supply, when the current absorbed by the output terminal Vout of the rail-to-rail output operational amplifier increases, the voltage of the controlled terminal VinN of the lower tube M2' rises, and the switching tube Q3' and the switching tube Q4' in the second protection circuit are turned on, so that the voltage of the controlled terminal VinN of the lower tube M2' cannot rise continuously, and finally the voltage of the controlled terminal VinN of the lower tube M2' is clamped at a certain fixed voltage value, where the fixed voltage value is the sum of the gate-source voltage drop of the switching tube Q3' and the gate-source voltage drop of the switching tube Q4', and the current absorbed by the output terminal Vout of the rail-to-rail output operational amplifier is limited to the fixed current value Imax.
However, if the power supply voltage VDD is large, if the current flowing through the lower tube M2' reaches a fixed value Imax in the case of short circuit of the output circuit to the power supply, the power of the lower tube M2' will reach Imax × VDD, which will cause the lower tube M2' to bear a large power, thereby causing thermal burnout of the rail-to-rail output op-amp in a very short time. And if the fixed current value Imax is reduced, the output current capability of the rail-to-rail output operational amplifier during normal operation is reduced. It can be seen that simply limiting the output current capability of the low rail-to-rail output operational amplifier can result in that the short-circuit protection circuit cannot perform reliable short-circuit protection on the output circuit when the power supply voltage is large, i.e., the conventional short-circuit protection circuit of the rail-to-rail output operational amplifier cannot simultaneously ensure that the rail-to-rail output operational amplifier has a large output current capability and can also realize reliable protection on the output circuit under the condition that the power supply voltage is large.
In order to solve the above technical problem, an embodiment of the present invention first provides a protection circuit for a rail-to-rail output operational amplifier, where a first detection unit is disposed between a power supply and an output terminal of the rail-to-rail output operational amplifier, a first power clamping unit and a first current clamping unit are disposed between the power supply and a controlled terminal of a first output tube, an input terminal and an output terminal of the first detection unit are respectively connected to the controlled terminal of the first output tube and a positive input terminal of the first comparison unit, an output terminal of the first comparison unit is connected to the controlled terminal of the first power clamping unit, so that the first detection unit detects a first current value flowing through the first output tube and outputs a first voltage signal corresponding to the first current value, when the voltage value of the first voltage signal is greater than a reference voltage value, the first comparison unit determines that the power of the first output tube is greater than a preset power threshold value, and outputs a first control signal, so that the first power clamping unit switches on a path between the controlled terminal of the first output tube and the power supply based on the first control signal, thereby reducing the current value flowing through the first output tube, and further reducing the current value of the first output tube, and enabling the first output rail-to have a capability of protecting the first output rail-to prevent the first output power clamp unit from being damaged when the first output tube from being shorted output rail-to cause a short circuit, and a short circuit.
Similarly, by arranging the second detection unit between the output end of the rail-to-rail output operational amplifier and the ground, by arranging the second power clamping unit and the second current clamping unit between the controlled end of the second output tube and the ground, by respectively connecting the input end and the output end of the second detection unit with the controlled end of the second output tube and the positive input end of the second comparison unit, and by connecting the output end of the second comparison unit with the controlled end of the second power clamping unit, the second detection unit detects the second current value flowing through the second output tube and outputs the second voltage signal corresponding to the second current value, so that the second comparison unit determines that the power of the second output tube is greater than the preset power threshold value when the voltage value of the second voltage signal is greater than the reference voltage value, and outputting a second control signal to enable the second power clamping unit to be connected with a passage between the controlled end of the second output tube and the ground based on the second control signal, so as to reduce the current value flowing through the second output tube and further reduce the power of the second output tube, and enable the second current clamping unit to clamp the second current value flowing through the second output tube at a preset current threshold value when the rail-to-rail output operational amplifier normally works, so that the rail-to-rail output operational amplifier can be ensured to have larger output current capability when normally works, and the power of the second output tube can be reduced when the power of the second output tube is larger than the preset power threshold value due to the power short circuit of the output circuit to the power supply, thereby avoiding the second output end from being burnt, and realizing reliable short circuit protection of the second output tube.
Fig. 2 is a schematic structural diagram of a protection circuit of a rail-to-rail output operational amplifier according to an embodiment of the present disclosure. As shown in fig. 2, the protection circuit is connected to an output circuit of the rail-to-rail output operational amplifier, and the protection circuit is used for performing short-circuit protection on the output circuit of the rail-to-rail output operational amplifier. The output circuit of the rail-to-rail output operational amplifier may include a first output tube M1 connected between a power supply and the output terminal Vout of the rail-to-rail output operational amplifier, and a second output tube M2 connected between the output terminal Vout of the rail-to-rail output operational amplifier and ground. Wherein, the power supply is used for providing a power supply voltage VDD. Specifically, the first conducting end of the first output tube M1 may be connected to a power supply, the second conducting end of the first output tube M1 may be connected to the first conducting end of the second output tube M2, the second conducting end of the second output tube M2 may be grounded, and the second conducting end of the first output tube M1 may serve as an output terminal Vout of the rail-to-rail output operational amplifier.
In the embodiment of the present application, the protection circuit of the rail-to-rail output operational amplifier may include a first protection circuit 11 and a second protection circuit 12. The first protection circuit 11 is configured to perform short-circuit protection on the first output tube M1, and the second protection circuit 12 is configured to perform short-circuit protection on the second output tube M2.
Specifically, the first protection circuit 11 may include a first detection unit 111, a first comparison unit 112, a first power clamping unit 113, and a first current clamping unit 114. The first detection unit 111 is connected between a power supply and an output terminal Vout of the rail-to-rail output operational amplifier, the first power clamp unit 113 and the first current clamp unit 114 are both connected between the power supply and a controlled terminal VinP of the first output tube M1, an input terminal of the first detection unit 111 is connected to the controlled terminal VinP of the first output tube M1, an output terminal of the first detection unit 111 is connected to a positive input terminal of the first comparison unit 112, and an output terminal of the first comparison unit 112 is connected to the controlled terminal of the first power clamp unit 113.
The first detecting unit 111 is configured to detect a first current value flowing through the first output tube M1, and output a first voltage signal corresponding to the first current value to the positive input end of the first comparing unit 112. The negative input end of the first comparing unit 112 is configured to receive a reference voltage signal, compare a voltage value of the first voltage signal with a reference voltage value corresponding to the reference voltage signal, determine that the power of the first output tube M1 is greater than a preset power threshold when the voltage value of the first voltage signal is greater than the reference voltage value, and output a first control signal to the first power clamping unit 113. The first power clamping unit 113 is configured to turn on a path between the controlled terminal VinP of the first output tube M1 and the power supply based on the first control signal, so as to reduce a first current value flowing through the first output tube M1, and further reduce the power of the first output tube M1. The first current clamping unit 114 is used for clamping the first current value flowing through the first output tube M1 to a preset current threshold.
Specifically, the second protection circuit 12 may include a second detection unit 121, a second comparison unit 122, a second power clamping unit 123, and a second current clamping unit 124. The second detecting unit 121 is connected between the output terminal Vout of the rail-to-rail output operational amplifier and ground, the second power clamping unit 123 and the second current clamping unit 124 are both connected between the controlled terminal VinN of the second output tube M2 and ground, the input terminal and the output terminal of the second detecting unit 121 are also connected to the controlled terminal VinN of the second output tube M2 and the positive input terminal of the second comparing unit 122, respectively, and the output terminal of the second comparing unit 122 is connected to the controlled terminal of the second power clamping unit 123.
The second detecting unit 121 is configured to detect a second current value flowing through the second output tube M2, and output a second voltage signal corresponding to the second current value to the non-inverting input terminal of the second comparator 122. The negative input end of the second comparing unit 122 is configured to receive the reference voltage signal, compare the voltage value of the second voltage signal with the reference voltage value corresponding to the reference voltage signal, determine that the power of the second output tube M2 is greater than the preset power threshold when the voltage value of the second voltage signal is greater than the reference voltage value, and output a second control signal to the second power clamping unit 123. The second power clamping unit 123 is configured to turn on a path between the controlled end VinN of the second output tube M2 and the ground based on the second control signal, so as to reduce a second current value flowing through the second output tube M2, and further reduce the power of the second output tube M2. The second current clamping unit 124 is used for clamping the second current value flowing through the second output tube M2 to the preset current threshold.
In this embodiment of the present application, the reference voltage signal may be generated by a reference voltage source, and a reference voltage value corresponding to the reference voltage signal may be set according to an actual requirement, which is not particularly limited herein.
The preset power threshold may be set according to actual requirements, and is not particularly limited herein.
Referring to fig. 3, a schematic structural diagram of a protection circuit of a rail-to-rail output operational amplifier according to another embodiment of the present application is shown, where the difference between this embodiment and the embodiment corresponding to fig. 2 is that the protection circuit of the rail-to-rail output operational amplifier in this embodiment may further include a reference voltage generating unit 13.
The input end of the reference voltage generating unit 13 is connected to the output end Vout of the rail-to-rail output operational amplifier, the power end of the reference voltage generating unit 13 is connected to the power supply, the ground end of the reference voltage generating unit 13 is grounded, and the output end of the reference voltage generating unit 13 is connected to the negative input end of the first comparing unit 112 and the negative input end of the second comparing unit 122. The reference voltage generating unit 13 is configured to generate a reference voltage signal, and a voltage value of the reference voltage signal is the reference voltage value.
Please refer to fig. 4, which is a schematic diagram of a circuit principle of a rail-to-rail output operational amplifier according to an embodiment of the present disclosure. As shown in fig. 4, in an embodiment of the present application, the first detection unit 111 may include a first switching tube Q1 and a first resistor R1. The first end of the first resistor R1 is connected to the power supply, the second end of the first resistor R1 is connected to the first conducting end of the first switch Q1, the second conducting end of the first switch Q1 is connected to the output terminal Vout of the rail-to-rail output operational amplifier, the controlled end of the first switch Q1 is the input end of the first detection unit 111, and the second end of the first resistor R1 is the output end of the first detection unit 111.
In yet another embodiment of the present application, the first comparing unit 112 may include a first comparator U1. The non-inverting input terminal of the first comparator U1 is the positive input terminal of the first comparing unit 112, the inverting input terminal of the first comparator U1 is the negative input terminal of the first comparing unit 112, and the output terminal of the first comparator U1 is the output terminal of the first comparing unit 112.
In yet another embodiment of the present application, the first power clamp unit 113 may include a second switching tube Q2 and a third switching tube Q3. A first conduction end of the second switching tube Q2 is connected to the power supply, a second conduction end of the second switching tube Q2 is connected to a first conduction end of the third switching tube Q3, a controlled end and a second conduction end of the third switching tube Q3 are commonly connected to a controlled end VinP of the first output tube M1, and the controlled end of the second switching tube Q2 is a controlled end of the first power clamping unit 113.
In another embodiment of the present application, the first current clamping unit 114 may include a fourth switching tube Q4, a fifth switching tube Q5 and a sixth switching tube Q6. The first conduction end of the fourth switching tube Q4 is connected with the power supply, the controlled end of the fourth switching tube Q4 and the second conduction end of the fourth switching tube Q4 are commonly connected to the first conduction end of the fifth switching tube Q5, the controlled end of the fifth switching tube Q5 and the second conduction end of the fifth switching tube Q5 are commonly connected to the first conduction end of the sixth switching tube Q6, and the controlled end of the sixth switching tube Q6 and the second conduction end of the sixth switching tube Q6 are commonly connected to the controlled end VinP of the first output tube M1.
In yet another embodiment of the present application, the second detection unit 121 may include a seventh switching tube Q7 and a second resistor R2. A first conduction end of the seventh switching tube Q7 is connected to the rail-to-rail output operational amplifier output end Vout, a second conduction end of the seventh switching tube Q7 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is grounded, the controlled end of the seventh switching tube Q7 is the input end of the second detection unit 121, and the first end of the second resistor R2 is the output end of the second detection unit 121.
In yet another embodiment of the present application, the second comparing unit 122 may include a second comparator U2. The non-inverting input terminal of the second comparator U2 is the positive input terminal of the second comparing unit 122, the inverting input terminal of the second comparator U2 is the negative input terminal of the second comparing unit 122, and the output terminal of the second comparator U2 is the output terminal of the second comparing unit 122.
In yet another embodiment of the present application, the second power clamping unit 123 may include an eighth switching tube Q8 and a ninth switching tube Q9. A first conduction end and a controlled end of the eighth switching tube Q8 are commonly connected to the controlled end VinN of the second output tube M2, a second conduction end of the eighth switching tube Q8 is connected to the first conduction end of the ninth switching tube Q9, the second conduction end of the ninth switching tube Q9 is grounded, and the controlled end of the ninth switching tube Q9 serves as the controlled end of the second power clamping unit 123.
In another embodiment of the present application, the second current clamping unit 124 may include a tenth switching tube Q10, an eleventh switching tube Q11 and a twelfth switching tube Q12. A first conduction end of a tenth switching tube Q10 and a controlled end of the tenth switching tube Q10 are commonly connected to a controlled end VinN of the second output tube M2, a first conduction end and a controlled end of an eleventh switching tube Q11 are commonly connected to a second conduction end of the tenth switching tube Q10, a first conduction end and a controlled end of a twelfth switching tube Q12 are commonly connected to a second conduction end of the eleventh switching tube Q11, and a second conduction end of the twelfth switching tube Q12 is grounded.
In still another embodiment of the present application, the reference voltage generating unit 13 may include a reference current generating unit 131 and a third resistor R3. A first terminal of the reference current generating unit 131 serves as an input terminal of the reference voltage generating unit 13, a second terminal of the reference current generating unit 131 serves as a power supply terminal of the reference voltage generating unit 13, a third terminal of the reference current generating unit 131 and a first terminal of the third resistor R3 are commonly connected as an output terminal of the reference voltage generating unit 13, and a fourth terminal of the reference current generating unit 131 and a second terminal of the third resistor R3 are commonly connected and serve as a ground terminal of the reference voltage generating unit 13.
In a specific embodiment, the reference current generating unit 131 may include a first operational amplifier U3, a thirteenth switching tube Q13, a fourth resistor R4, a fourteenth switching tube Q14, a fifteenth switching tube Q15, a sixteenth switching tube Q16, a seventeenth switching tube Q17, an eighteenth switching tube Q18, a nineteenth switching tube Q19, a twentieth switching tube Q20, a twenty-first switching tube Q21, a twenty-second switching tube Q22, a twentieth switching tube Q23, a first current source CS1, and a second current source CS2. A non-inverting input terminal of the first operational amplifier U3 is used as a first terminal of the reference current generating unit 131, an inverting input terminal of the first operational amplifier U3 and a first terminal of the fourth resistor R4 are commonly connected to a first conducting terminal of the thirteenth switching tube Q13, an output terminal of the first operational amplifier U3 is connected to a controlled terminal of the thirteenth switching tube Q13, a second conducting terminal of the thirteenth switching tube Q13, a first conducting terminal of the fourteenth switching tube Q14 and a controlled terminal of the fourteenth switching tube Q14 are commonly connected to a controlled terminal of the fifteenth switching tube Q15, a first conducting terminal of the sixteenth switching tube Q16, a controlled terminal of the sixteenth switching tube Q16 and a controlled terminal of the seventeenth switching tube Q17 are commonly connected to a first conducting terminal of the fifteenth switching tube Q15, a first conducting terminal of the seventeenth switching tube Q17 and a first conducting terminal of the eighteenth switching tube Q18 are commonly connected to a controlled terminal of the nineteenth switching tube Q19, a first conduction end of a nineteenth switching tube Q19, a first conduction end of a twentieth switching tube Q20 and a controlled end of a twentieth switching tube Q20 are commonly connected to a controlled end of a twenty-first switching tube Q21, a controlled end of an eighteenth switching tube Q18, an output end of a first current source CS1 and a first conduction end of a twenty-second switching tube Q22 are commonly connected to a controlled end of a twentieth switching tube Q23, a controlled end of a twenty-second switching tube Q22 and a first conduction end of a twentieth switching tube Q23 are commonly connected to an input end of a second current source CS2, a second end of a fourth resistor R4, a second conduction end of a sixteenth switching tube Q16, a second conduction end of a seventeenth switching tube Q17, a second conduction end of a nineteenth switching tube Q19, a second conduction end of a twenty-second switching tube Q22 and an output end of a second current source CS2 are all grounded, a second conduction end of a fourteenth switching tube Q14, a fifteenth switching tube Q15 and a eighteenth conduction end of a fifteenth switching tube Q18 are commonly connected to a controlled end of a fourteenth switching tube Q14, a eighteen switching tube Q18, the second conducting end of the twentieth switch tube Q20, the input end of the first current source CS1, the second conducting end of the twentieth switch tube Q23 and the second conducting end of the twenty-first switch tube Q21 are all connected to the power supply.
In an embodiment of the present application, the first output pipe M1 may be a P-type metal-oxide-semiconductor field-effect transistor (MOSFET), based on which a gate of the PMOS transistor may be a controlled end of the first output pipe M1, a source of the PMOS transistor may be a first conducting end of the first output pipe M1, and a drain of the PMOS transistor may be a second conducting end of the first output pipe M1. The second output tube M2 may be an NMOS tube, and based on this, the gate of the NMOS tube may be the controlled end of the second output tube M2, the drain of the NMOS tube may be the first conducting end of the second output tube M2, and the source of the NMOS tube may be the second conducting end of the second output tube M2. Based on this, the first control signal may be a low level signal, and the second control signal may be a high level signal.
Of course, in other embodiments, the first output pipe M1 and the second output pipe M2 may be other types of power pipes. For example, the first output tube M1 may also be a PNP-type triode, the second output tube M2 may also be an NPN-type triode, and the specific types of the first output tube M1 and the second output tube M2 are not particularly limited in this embodiment of the application.
In an embodiment of the present application, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, the fifth switching tube Q5, the sixth switching tube Q6, the fourteenth switching tube Q14, the fifteenth switching tube Q15, the twentieth switching tube Q20, and the twenty-first switching tube Q21 may be PMOS tubes, P-type triodes, or the like. The seventh switch tube Q7, the eighth switch tube Q8, the ninth switch tube Q9, the tenth switch tube Q10, the eleventh switch tube Q11, the twelfth switch tube Q12, the thirteenth switch tube Q13, the sixteenth switch tube Q16, the seventeenth switch tube Q17, the eighteenth switch tube Q18, the nineteenth switch tube Q19, the twenty second switch tube Q22, and the twentieth switch tube Q23 may be NMOS tubes or NPN-type triodes, etc., and the specific types of the switch tubes are not particularly limited in the present application.
The working principle of the protection circuit of the rail-to-rail output operational amplifier provided in the embodiment of the present application is described below with reference to fig. 4.
Taking short-circuit protection of the second output terminal M2 as an example, the seventh switching tube Q7 is configured to detect a second current value flowing through the second output tube M2 and generate a second mirror current corresponding to the second current value, where the current value of the second mirror current is a current value flowing through the seventh switching tube Q7 and the second resistor R2. Assuming that the mirror ratio of the second mirror current is K1, and the current value drawn by the second output tube M2 is IOUT, the current value I1 flowing through the second resistor R2 may be K1 × IOUT. K1 can be set according to actual requirements, and in specific applications, the current mirror proportion of the second mirror current can be adjusted by adjusting the ratio of the width-to-length ratio of the seventh switching tube Q7 to the width-to-length ratio of the second output tube M2.
The tenth switching tube Q10, the eleventh switching tube Q11 and the twelfth switching tube Q12 are used for clamping the maximum suction current value Imax of the second output tube M2, the eighth switching tube Q8 and the ninth switching tube Q9 are used for clamping the maximum power of the second output tube M2, and the second comparator U2 is used for judging whether the power of the second output tube M2 exceeds a preset power threshold. Specifically, when the output terminal Vout of the rail-to-rail output operational amplifier is short-circuited to the power supply, so that I1 × R2 (R2 is the resistance value of the second resistor R2) is greater than the reference voltage value, the power of the second output tube M2 is greater than the preset power threshold, at this time, the second comparator U2 outputs a high level signal, the ninth switching tube Q9 is turned on, and the voltage of the controlled terminal VinN of the second output tube M2 decreases, so that the second current value flowing through the second output tube M2 (i.e., the suction current value IOUT of the second output tube M2) is reduced, and further the power of the second output tube M2 is reduced, so that the power of the second output tube M2 is reduced to within the preset power threshold.
The reference voltage value may be Ib × R3, R3 is a resistance value of the third resistor R3, and Ib is a reference current value generated by the reference current generating unit 131, where the reference current value is inversely proportional to the voltage Vout of the output terminal Vout of the rail-to-rail output operational amplifier, that is, ib = K2/Vout. When the rail-to-rail output operational amplifier normally works, I1 × r2< Ib × r3, i.e., K1 × IOUT × r2< K2/VOUT × r3, i.e., IOUT × VOUT < K2 × r 3/(K1 × r 2), that is, the maximum power of the second output tube M2 is limited to K2 × r 3/(K1 × r 2), and since K1, K2, r2, and r3 are all constants, the maximum power of the second output tube M2 is limited to a constant, i.e., the preset power threshold is K2 × r 3/(K1 × r 2).
It should be noted that the working principle when performing short-circuit protection on the first output tube M1 is similar to the working principle when performing short-circuit protection on the second output tube M2, and therefore, the working principle when performing short-circuit protection on the first output tube M1 may specifically refer to the working principle when performing short-circuit protection on the second output tube M2, and the working principle when performing short-circuit protection on the first output tube M1 is not described herein again.
The operation principle of the reference current generation unit 131 for generating the reference current Ib will be described below.
The first operational amplifier U3 is configured to clamp the voltage Vout at the output terminal Vout of the rail-to-rail output operational amplifier and output the clamped voltage Vout, so that the current value I0= Vout/R4 flowing through the fourteenth switching transistor Q14, R4 is the resistance of the fourth resistor R4, and since the fifteenth switching transistor Q15 mirrors the fourteenth switching transistor Q14 and the seventeenth switching transistor Q17 mirrors the sixteenth switching transistor Q16, the current value flowing through the seventeenth switching transistor Q17 is also I0. Neglecting the base current of the eighteenth switching tube Q18, the current value flowing through the eighteenth switching tube Q18 is also I0, assuming that the current value provided by the first current source CS1 is I1', the current value provided by the second current source CS2 is I2', and the current value flowing through the twentieth switching tube Q20 and the nineteenth switching tube Q19 is Ib, since Vbe18+ Vbe19= Vbe22+ Vbe23, I0 × Ib = I1 '/I2' can be obtained, ib = I1 '/I2'/I0 = r4 × I1 '/I2'/VOUT, it can be seen that the current value flowing through the twentieth switching tube Q20 is inversely proportional to the voltage VOUT of the rail-to-rail output operational amplifier output terminal VOUT, and since the twenty-first switching tube Q21 mirrors the twentieth switching tube Q20, the current value flowing through the twenty-first switching tube Q21 is also Ib.
Wherein, vbe18 is the voltage drop between the base and the emitter of the eighteenth switching tube Q18, vbe19 is the voltage drop between the base and the emitter of the nineteenth switching tube Q19, vbe22 is the voltage drop between the base and the emitter of the twenty-second switching tube Q22, and Vbe23 is the voltage drop between the base and the emitter of the twentieth switching tube Q23.
The embodiment of the present application further provides a display screen, and the display screen may be, for example, a Liquid Crystal Display (LCD). Fig. 5 is a schematic structural diagram of a display screen according to an embodiment of the present disclosure. As shown in fig. 5, the display screen 50 may include a rail-to-rail output op-amp 51 and a rail-to-rail output op-amp protection circuit 52 connected to the rail-to-rail output op-amp 51. The rail-to-rail output operational amplifier 51 can be applied to a deflection circuit of an LCD, and particularly, can be applied to a high-voltage high-power scene.
In one embodiment of the present application, the rail-to-rail output op-amp 51 may include an input circuit 511, an amplification circuit 512, and an output circuit 513 sequentially connected between the input terminal (VIN +, VIN-) and the output terminal Vout of the rail-to-rail output op-amp 51. The output circuit 513 may include a first output tube M1 connected between the power supply and the output terminal Vout of the rail-to-rail output operational amplifier, and a second output tube M2 connected between the output terminal Vout of the rail-to-rail output operational amplifier and the ground GND.
Specifically, the protection circuit 52 of the rail-to-rail output operational amplifier may be connected to the controlled terminal VinP of the first output tube M1, the controlled terminal VinN of the second output tube M2, and the output terminal Vout of the rail-to-rail output operational amplifier.
It should be noted that the protection circuit 52 of the rail-to-rail output operational amplifier may be the protection circuit in any embodiment of fig. 2 to 4, and for details of the protection circuit 52 of the rail-to-rail output operational amplifier, reference is made to the relevant description in each embodiment of fig. 2 to 4, and details are not repeated here.
In the above embodiments, the description of each embodiment has its own emphasis, and parts that are not described or illustrated in a certain embodiment may refer to the description of other embodiments.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims (10)

1. A protection circuit of a rail-to-rail output operational amplifier is characterized by being connected with an output circuit of the rail-to-rail output operational amplifier; the output circuit comprises a first output tube connected between a power supply and the output end of the rail-to-rail output operational amplifier and a second output tube connected between the output end and the ground; the protection circuit comprises a first detection unit, a first comparison unit, a first power clamping unit, a first current clamping unit, a second detection unit, a second comparison unit, a second power clamping unit and a second current clamping unit;
the first detection unit is connected between the power supply and the output end, the first power clamping unit and the first current clamping unit are both connected between the power supply and the controlled end of the first output tube, the input end and the output end of the first detection unit are also respectively connected with the controlled end of the first output tube and the positive input end of the first comparison unit, and the output end of the first comparison unit is connected with the controlled end of the first power clamping unit; the second detection unit is connected between the output end of the rail-to-rail output operational amplifier and the ground, the second power clamping unit and the second current clamping unit are both connected between the controlled end of the second output tube and the ground, the input end and the output end of the second detection unit are also respectively connected with the controlled end of the second output tube and the positive input end of the second comparison unit, and the output end of the second comparison unit is connected with the controlled end of the second power clamping unit;
the first detection unit is used for detecting a first current value flowing through the first output tube and outputting a first voltage signal corresponding to the first current value; the first comparison unit is used for determining that the power of the first output tube is greater than a preset power threshold value and outputting a first control signal when the voltage value of the first voltage signal is greater than a reference voltage value; the first power clamping unit is used for switching on a path between the controlled end of the first output tube and the power supply based on the first control signal; the first current clamping unit is used for clamping the first current value flowing through the first output tube at a preset current threshold value;
the second detection unit is used for detecting a second current value flowing through the second output tube and outputting a second voltage signal corresponding to the second current value; the second comparing unit is used for determining that the power of the second output tube is greater than the preset power threshold value and outputting a second control signal when the voltage value of the second voltage signal is greater than the reference voltage value; the second power clamping unit is used for switching on a path between the controlled end of the second output tube and the ground based on the second control signal; the second current clamping unit is used for clamping the second current value flowing through the second output tube at a preset current threshold value.
2. The protection circuit according to claim 1, wherein the first detection unit comprises a first switch tube and a first resistor; the first end of first resistance is connected the power, the second end of first resistance is connected the first switch-on end of first switch tube, the second switch-on end of first switch tube is connected the output that rail-to-rail output fortune was put, the controlled end of first switch tube is the input of first detecting element, the second end of first resistance is the output of first detecting element.
3. The protection circuit of claim 1, wherein the first power clamp unit comprises a second switching tube and a third switching tube; the first conduction end of the second switch tube is connected with the power supply, the second conduction end of the second switch tube is connected with the first conduction end of the third switch tube, the controlled end and the second conduction end of the third switch tube are connected to the controlled end of the first output tube, and the controlled end of the second switch tube is the controlled end of the first power clamping unit.
4. The protection circuit of claim 1, wherein the first current clamping unit comprises a fourth switching tube, a fifth switching tube and a sixth switching tube; the first end of turning on of fourth switch tube is connected the power, the controlled end of fourth switch tube with the second end of turning on of fourth switch tube connect in the first end of turning on of fifth switch tube altogether, the controlled end of fifth switch tube with the second end of turning on of fifth switch tube connect in the first end of turning on of sixth switch tube altogether, the controlled end of sixth switch tube with the second end of turning on of sixth switch tube connect in the controlled end of first output tube altogether.
5. The protection circuit according to claim 1, wherein the second detection unit comprises a seventh switch tube and a second resistor; the first conduction end of the seventh switch tube is connected with the output end of the rail-to-rail output operational amplifier, the second conduction end of the seventh switch tube is connected with the first end of the second resistor, the second end of the second resistor is grounded, the controlled end of the seventh switch tube is the input end of the second detection unit, and the first end of the second resistor is the output end of the second detection unit.
6. The protection circuit of claim 1, wherein the second power clamp unit comprises an eighth switching tube and a ninth switching tube; the first conducting end and the controlled end of the eighth switching tube are commonly connected to the controlled end of the second output tube, the second conducting end of the eighth switching tube is connected to the first conducting end of the ninth switching tube, the second conducting end of the ninth switching tube is grounded, and the controlled end of the ninth switching tube is used as the controlled end of the second power clamping unit.
7. The protection circuit of claim 1, wherein the second current clamping unit comprises a tenth switching tube, an eleventh switching tube and a twelfth switching tube; the first conducting end and the controlled end of the tenth switching tube are connected to the controlled end of the second output tube, the first conducting end and the controlled end of the eleventh switching tube are connected to the second conducting end of the tenth switching tube, the first conducting end and the controlled end of the twelfth switching tube are connected to the second conducting end of the eleventh switching tube, and the second conducting end of the twelfth switching tube is grounded.
8. The protection circuit according to any one of claims 1 to 7, characterized in that the protection circuit further comprises a reference voltage generating unit; the input end of the reference voltage generating unit is connected with the output end of the rail-to-rail output operational amplifier, the power supply end of the reference voltage generating unit is connected with the power supply, the ground end of the reference voltage generating unit is grounded, and the output end of the reference voltage generating unit is connected with the negative input end of the first comparing unit and the negative input end of the second comparing unit;
the reference voltage generating unit is used for generating a reference voltage signal; the voltage value of the reference voltage signal is the reference voltage value.
9. The protection circuit according to claim 8, wherein the reference voltage generating unit includes a reference current generating unit and a third resistor; a first end of the reference current generating unit is used as an input end of the reference voltage generating unit, a second end of the reference current generating unit is used as a power supply end of the reference voltage generating unit, a third end of the reference current generating unit and a first end of the third resistor are connected in common to serve as an output end of the reference voltage generating unit, and a fourth end of the reference current generating unit and a second end of the third resistor are connected in common to serve as a ground end of the reference voltage generating unit;
the reference current generating unit comprises a first operational amplifier, a thirteenth switching tube, a fourth resistor, a fourteenth switching tube, a fifteenth switching tube, a sixteenth switching tube, a seventeenth switching tube, an eighteenth switching tube, a nineteenth switching tube, a twentieth switching tube, a twenty-first switching tube, a twenty-second switching tube, a twentieth switching tube, a first current source and a second current source; a non-inverting input terminal of the first operational amplifier is used as a first terminal of the reference current generating unit, an inverting input terminal of the first operational amplifier and a first terminal of the fourth resistor are commonly connected to a first conducting terminal of the thirteenth switching tube, an output terminal of the first operational amplifier is connected to a controlled terminal of the thirteenth switching tube, a second conducting terminal of the thirteenth switching tube, a first conducting terminal of the fourteenth switching tube and a controlled terminal of the fourteenth switching tube are commonly connected to a controlled terminal of the fifteenth switching tube, a first conducting terminal of the sixteenth switching tube, a controlled terminal of the sixteenth switching tube and a controlled terminal of the seventeenth switching tube are commonly connected to a first conducting terminal of the fifteenth switching tube, a first conducting terminal of the seventeenth switching tube and a first conducting terminal of the eighteenth switching tube are commonly connected to a controlled terminal of the nineteenth switch, the first conducting end of the nineteenth switch, the first conducting end of the twentieth switch tube and the controlled end of the twentieth switch tube are connected to the controlled end of the twenty-first switch tube, the controlled end of the eighteenth switch tube, the output end of the first current source and the first conducting end of the twenty-second switch tube are connected to the controlled end of the twenty-second switch tube, the controlled end of the twenty-second switch tube and the first conducting end of the twentieth switch tube are connected to the input end of the second current source, the second end of the fourth resistor, the second conducting end of the sixteenth switch tube, the second conducting end of the seventeenth switch tube, the second conducting end of the nineteenth switch, the second conducting end of the twenty-second switch tube and the output end of the second current source are all grounded, and the second conducting end of the fourteenth switch tube, the first conducting end of the twentieth switch tube and the second conducting end of the second current source are all grounded, the second conduction end of the fifteenth switch tube, the second conduction end of the eighteenth switch tube, the second conduction end of the twentieth switch tube, the input end of the first current source, the second conduction end of the twentieth switch tube and the second conduction end of the twenty-first switch tube are all connected with the power supply.
10. A display screen comprising a rail-to-rail output op amp and a protection circuit as claimed in any one of claims 1 to 9, the protection circuit being connected to the rail-to-rail output op amp.
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史柱: "一种低电压轨到轨运算放大器的研究与设计", 《中国优秀博硕士学位论文全文数据库（硕士）信息科技辑》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117518042A (en) * 2024-01-05 2024-02-06 赛卓电子科技(上海)股份有限公司 Output stage circuit and sensor
CN117518042B (en) * 2024-01-05 2024-04-30 赛卓电子科技(上海)股份有限公司 Output stage circuit and sensor

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