A power supply voltage comparison circuit

Abstract

The present application discloses a power supply voltage comparison circuit, which relates to the field of voltage detection technology. The circuit includes a startup module, an input module, a comparison module and an output module. The startup module generates a startup signal after the power supply voltage VIN is turned on, and inputs the startup signal to the input module; the input module is connected to the second input voltage V2, used to generate a reference current and a reference voltage VB, and inputs the reference voltage VB into the comparison module; the comparison module generates a comparison signal according to the power supply voltage VIN and the second input voltage V2, and inputs the comparison signal into the output module; the output module generates and outputs a comparison voltage VOUT based on the comparison signal. This solution realizes a direct comparison between the second input voltage V2 and the power supply voltage VIN, saves the number of circuit ports, reduces the circuit area, and the high and low level switching points of the comparison voltage VOUT are not affected by temperature, which improves the accuracy of the circuit and the performance and reliability under different temperature environments.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage detection, and in particular to a power supply voltage comparison circuit. Background Art

[0002] Voltage comparison circuit plays a key role in electronic devices. It is mainly used to compare two input voltages and output the corresponding comparison results. Figure 1 As shown, a typical voltage comparison circuit generally includes four input terminals and one output terminal. The four input terminals are respectively used to input a first input voltage V1, a second input voltage V2, a power supply voltage VIN and a ground voltage GND, and the output terminal is used to output a comparison voltage VOUT.

[0003] However, the voltage comparison circuit in the prior art has certain limitations. First, this type of circuit usually needs to set up five ports, which increases the complexity of the circuit and the difficulty of design. Secondly, the input voltage needs to be less than the power supply voltage VIN. When a voltage equal to the power supply voltage needs to be input, a resistor divider circuit must be set outside the voltage comparison circuit to divide the input voltage before inputting it into the voltage comparison circuit, resulting in a complex circuit structure and a large area. In addition, the existing voltage comparison circuit is easily affected by temperature changes, especially in applications with a large temperature change range, the error of the voltage comparison circuit is large, affecting its performance and reliability.

[0004] Therefore, how to design a voltage comparison circuit with fewer ports, smaller area and less susceptible to temperature changes has become a problem to be solved urgently in the current technical field. Summary of the invention

[0005] The object of the present invention is to provide a power supply voltage comparison circuit with fewer ports, smaller area and higher precision, which can realize direct comparison between input voltage and power supply voltage and improve the precision and reliability of the circuit under different temperature environments.

[0006] To achieve the above object, the present invention discloses the following technical solution:

[0007] The present invention provides a power supply voltage comparison circuit, which includes a startup module, an input module, a comparison module and an output module;

[0008] The startup module is used to generate a startup signal after the power supply voltage VIN is turned on, and input the startup signal into the input module; the input module is connected to the second input voltage V2, used to generate a reference current and a reference voltage VB, and input the reference voltage VB into the comparison module; the comparison module is used to generate a comparison signal according to the power supply voltage VIN and the second input voltage V2, and input the comparison signal into the output module; the output module generates and outputs a comparison voltage VOUT based on the comparison signal.

[0009] In a possible implementation, in the input module, the power supply voltage VIN is connected to the startup module and the output module through the first branch of the first current mirror and the fifth branch of the first current mirror, respectively; the power supply voltage VIN is also connected to the ground through the second branch of the first current mirror and the first transistor Q1 in turn; the power supply voltage VIN is also connected to the ground through the third branch of the first current mirror and the second resistor R2 in turn; the power supply voltage VIN is also connected to the ground through the first branch of the second current mirror and the proportional current source unit in turn; the power supply voltage VIN is also connected to the second node B through the second branch of the second current mirror and the fourth branch of the first current mirror, respectively; the second input voltage V2 is connected to the second node B through the eighth resistor R8, for outputting the reference voltage VB.

[0010] In a possible implementation, the proportional current source unit includes a first current branch and a second current branch;

[0011] In the first current branch, the output end of the first branch of the second current mirror is grounded through the third resistor R3, the third transistor Q3 and the fourth resistor R4 in sequence;

[0012] In the second current branch, the output end of the first branch of the second current mirror is grounded through the fourth transistor Q4 and the fifth resistor R5 in sequence, and the control end of the fourth transistor Q4 is connected to the control end of the third transistor Q3 and grounded.

[0013] In a possible implementation, the proportional current source unit further includes a first operational amplifier A1;

[0014] The current output end of the third transistor Q3 is connected to the inverting input end of the first operational amplifier A1, the current output end of the fourth transistor Q4 is connected to the non-inverting input end of the first operational amplifier A1, and the output end of the first operational amplifier A1 is connected to the reference node of the second current mirror.

[0015] In a possible implementation manner, the ratio of the number of the third transistor Q3 to the number of the fourth transistor Q4 is N:1, and N≥2.

[0016] In a possible implementation, the fourth resistor R4 and the fifth resistor R5 have the same resistance.

[0017] In a possible implementation of the above circuit structure, when the voltage difference between the power supply voltage VIN and the second input voltage V2 is greater than a preset value, the comparison voltage VOUT is a low level; when the voltage difference between the power supply voltage VIN and the second input voltage V2 is less than a preset value, the comparison voltage VOUT is a high level.

[0018] In a possible implementation, the first branch of the first current mirror includes a first switch tube M1, the second branch includes a second switch tube M2, the third branch includes a third switch tube M3, the fourth branch includes a fourth switch tube M4, and the fifth branch includes a fifth switch tube M5, and the control end of the first switch tube M1, the control end of the second switch tube M2, the control end of the third switch tube M3, and the control end of the fourth switch tube M4 are connected to the control end of the fifth switch tube M5 and connected to the current output end of the second switch tube M2.

[0019] In a possible implementation, the first branch of the second current mirror includes an eighth switch tube M8, and the second branch includes a ninth switch tube M9. The control end of the eighth switch tube M8 is connected to the control end of the ninth switch tube M9, and the connection point between the control end of the eighth switch tube M8 and the control end of the ninth switch tube M9 is a reference node of the second current mirror.

[0020] In a possible implementation, the first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4 and the fifth switch tube M5 form a 1:1:1:M:1 current mirror, and the eighth switch tube M8 and the ninth switch tube M9 form a 1:Y current mirror.

[0021] In a possible implementation, in the comparison module, the power supply voltage VIN is grounded through the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6 in sequence, and the control end of the seventh switch tube M7 is connected to the second node B, the base of the second transistor Q2 is connected to the base of the first transistor Q1 and connected to the current output end of the third switch tube M3; the power supply voltage VIN is also connected to the output module through the eleventh switch tube M11, and the control end of the eleventh switch tube M11 is connected to the fifth node E between the seventh switch tube M7 and the second transistor Q2;

[0022] When the circuit is started, a ninth current I9 is ​​generated in the branch consisting of the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6.

[0023] In a possible implementation manner, the parameters of the first transistor Q1 and the second transistor Q2 are the same; and the turn-on voltages of the seventh switch tube M7 and the eleventh switch tube M11 are the same.

[0024] In a possible implementation, the output module includes a seventh resistor R7 and a twelfth switch tube M12;

[0025] In the output module, one end of the seventh resistor R7 is connected to the current output end of the eleventh switch tube M11, and the other end of the seventh resistor R7 is grounded; the current input end of the twelfth switch tube M12 is connected to the current output end of the fifth switch tube M5, the current output end of the twelfth switch tube M12 is grounded, and the control end of the twelfth switch tube M12 is connected to the current output end of the eleventh switch tube M11, and its current input end is used to output the comparison voltage VOUT.

[0026] In a possible implementation manner, the current capability of the twelfth switch tube M12 is greater than the current capability of the fifth switch tube M5.

[0027] In a possible implementation, the startup module includes a first resistor R1, a sixth switch tube M6, and a tenth switch tube M10;

[0028] In the startup module, one end of the first resistor R1 is connected to the current output end of the first switch tube M1, and the other end of the first resistor R1 is grounded; the power supply voltage VIN is connected to the current output end of the third switch tube M3 through the sixth switch tube M6; the control end of the tenth switch tube M10 is connected to the control end of the sixth switch tube M6 and connected to the current output end of the first switch tube M1, the current input end of the tenth switch tube M10 is connected to the output end of the first operational amplifier A1, and the current output end of the tenth switch tube M10 is grounded.

[0029] In a possible implementation, a resistance value of the first resistor R1 is greater than or equal to 1 MΩ, and a resistance value of the seventh resistor R7 is greater than or equal to 1 MΩ.

[0030] In a possible implementation, the seventh switch tube M7 is an NMOS tube, and the eleventh switch tube M11 is a PMOS tube;

[0031] The first transistor Q1 and the second transistor Q2 are NPN transistors;

[0032] The third transistor Q3 and the fourth transistor Q4 are PNP transistors;

[0033] The first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4, the fifth switch tube M5, the sixth switch tube M6, the eighth switch tube M8, the ninth switch tube M9, and the tenth switch tube M10 are all PMOS tubes or PNP transistors;

[0034] The twelfth switch tube M12 is an NMOS tube or an NPN transistor.

[0035] In a possible implementation, when the voltage difference between the power supply voltage VIN and the second input voltage V2 is greater than a preset value, the eleventh switch tube M11 and the twelfth switch tube M12 are turned on, and the comparison voltage VOUT is at a low level;

[0036] When the voltage difference between the power supply voltage VIN and the second input voltage V2 is less than a preset value, the eleventh switch tube M11 and the twelfth switch tube M12 are turned off, and the comparison voltage VOUT is at a high level.

[0037] In a possible implementation, the preset value is I8×R8, where I8 is the current flowing through the eighth resistor R8, I8 is a zero temperature coefficient current, and R8 is a zero temperature coefficient resistor.

[0038] In a possible implementation, the ninth current I9 is ​​set to be less than 0.1 μA.

[0039] The effects provided in the content of the invention are only the effects of the embodiments, not all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects:

[0040] The present application provides a power supply voltage comparison circuit, which includes a startup module, an input module, a comparison module and an output module. The startup module generates a startup signal after the power supply voltage VIN is turned on, and inputs the startup signal to the input module; the input module is connected to the second input voltage V2, used to generate a reference current and a reference voltage VB, and inputs the reference voltage VB into the comparison module; the comparison module generates a comparison signal according to the power supply voltage VIN and the second input voltage V2, and inputs the comparison signal into the output module; the output module generates and outputs a comparison voltage VOUT based on the comparison signal. The present application can determine the size of the second input voltage V2 relative to the power supply voltage VIN according to the level of the comparison voltage VOUT, realize the direct comparison of the second input voltage V2 with the power supply voltage VIN, save the circuit port, simplify the circuit structure, and reduce the circuit area. At the same time, the high and low level switching points of the comparison voltage VOUT of the present application are not affected by temperature, which reduces the error caused by temperature changes, improves the accuracy of the circuit and the performance and reliability under different temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0042] Figure 1 It is a schematic diagram of a voltage comparison circuit in the prior art;

[0043] Figure 2 This is a schematic diagram of the structure of a power supply voltage comparison circuit according to an embodiment of the present application;

[0044] Figure 3 This is a schematic diagram of a power supply voltage comparison circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] It should be noted that references to "one embodiment", "embodiment", "example embodiment", etc. in this specification refer to the embodiment being described which may include specific features, structures or characteristics, but not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Furthermore, when describing specific features, structures or characteristics in conjunction with an embodiment, whether or not there is an explicit description, it is indicated that incorporating such features, structures or characteristics into other embodiments is within the knowledge of those skilled in the art.

[0047] Figure 1 FIG. 1 is a schematic diagram of a voltage comparison circuit in the prior art. Figure 1 As shown, the voltage comparison circuit needs to be set with four input terminals and one output terminal. When a voltage equal to the power supply voltage needs to be input, a resistor voltage divider circuit is also set outside the voltage comparison circuit, resulting in many circuit ports, complex structure and large area, and is greatly affected by temperature changes. Based on this, the present application provides a power supply voltage comparison circuit, which can directly compare the input voltage with the power supply voltage, saves the number of circuit ports, reduces the circuit area, and the high and low level switching points of the comparison voltage are not affected by temperature, thereby improving the accuracy of the circuit.

[0048] refer to Figure 2 , Figure 2The structural schematic diagram of the power supply voltage comparison circuit of the embodiment of the present application is shown. As shown in the figure, the power supply voltage comparison circuit includes a startup module 210, an input module 220, a comparison module 230 and an output module 240. Among them, the startup module 210 is used to generate a startup signal after the power supply voltage VIN is turned on, and the startup signal is input to the input module 220. The input module 220 is connected to the second input voltage V2, used to generate a reference current and a reference voltage VB, and input the reference voltage VB into the comparison module 230. The comparison module 230 is used to generate a comparison signal according to the power supply voltage VIN and the second input voltage V2, and input the comparison signal into the output module 240. The output module 240 generates and outputs a comparison voltage VOUT based on the comparison signal. According to the level of the comparison voltage VOUT, this circuit can determine the size of the second input voltage V2 relative to the power supply voltage VIN.

[0049] Figure 3 FIG. 1 is a schematic diagram of a power supply voltage comparison circuit according to an embodiment of the present application. Figure 3 As shown, in the input module 220 of the present embodiment, the power supply voltage VIN is connected to the startup module 210 and the output module 240 respectively through the first branch of the first current mirror and the fifth branch of the first current mirror. The power supply voltage VIN is also connected to the ground through the second branch of the first current mirror and the first transistor Q1 in sequence. The power supply voltage VIN is also connected to the ground through the third branch of the first current mirror and the second resistor R2 in sequence. The power supply voltage VIN is also connected to the ground through the first branch of the second current mirror and the proportional current source unit in sequence. The power supply voltage VIN is also connected to the second node B through the second branch of the second current mirror and the fourth branch of the first current mirror, respectively. The second input voltage V2 is connected to the second node B through the eighth resistor R8 for outputting the reference voltage VB.

[0050] In the circuit of this embodiment, when the voltage difference between the power supply voltage VIN and the second input voltage V2 is greater than a preset value, the comparison voltage VOUT is at a low level. When the voltage difference between the power supply voltage VIN and the second input voltage V2 is less than a preset value, the comparison voltage VOUT is at a high level. According to the level of the comparison voltage VOUT, the magnitude of the second input voltage V2 relative to the power supply voltage VIN can be determined, and a direct comparison between the second input voltage V2 and the power supply voltage VIN is achieved, saving circuit ports. At the same time, the high and low level switching points of the comparison voltage VOUT of the circuit are not affected by temperature, which can reduce the error caused by temperature changes and improve the accuracy of the circuit and the performance under different temperature environments.

[0051] Continue to refer Figure 3In this embodiment, the proportional current source unit includes a first current branch and a second current branch. In the first current branch, the output end of the first branch of the second current mirror is grounded through the third resistor R3, the third triode Q3 and the fourth resistor R4 in sequence. In the second current branch, the output end of the first branch of the second current mirror is grounded through the fourth triode Q4 and the fifth resistor R5 in sequence, and the control end of the fourth triode Q4 is connected to the control end of the third triode Q3 and grounded. The proportional current source unit also includes a first operational amplifier A1, the current output end of the third triode Q3 is connected to the inverting input end of the first operational amplifier A1, the current output end of the fourth triode Q4 is connected to the non-inverting input end of the first operational amplifier A1, and the output end of the first operational amplifier A1 is connected to the reference node of the second current mirror.

[0052] In some embodiments, the number ratio of the third transistor Q3 to the fourth transistor Q4 is N:1, and N≥2. The fourth resistor R4 and the fifth resistor R5 have the same resistance value.

[0053] In some embodiments, the first branch of the first current mirror includes the first switch tube M1, the second branch includes the second switch tube M2, the third branch includes the third switch tube M3, the fourth branch includes the fourth switch tube M4, and the fifth branch includes the fifth switch tube M5, and the control end of the first switch tube M1, the control end of the second switch tube M2, the control end of the third switch tube M3, and the control end of the fourth switch tube M4 are connected to the control end of the fifth switch tube M5 and connected to the current output end of the second switch tube M2. The first branch of the second current mirror includes the eighth switch tube M8, the second branch includes the ninth switch tube M9, and the control end of the eighth switch tube M8 is connected to the control end of the ninth switch tube M9, and the connection point is the reference node of the second current mirror. In addition, in some embodiments, the first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4, and the fifth switch tube M5 constitute a 1:1:1:M:1 current mirror, and the eighth switch tube M8 and the ninth switch tube M9 constitute a 1:Y current mirror.

[0054] Continue to refer Figure 3 In the comparison module 230 of the present embodiment, the power supply voltage VIN is connected to the ground through the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6 in sequence, and the control end of the seventh switch tube M7 is connected to the second node B, and the base of the second transistor Q2 is connected to the base of the first transistor Q1 and connected to the current output end of the third switch tube M3. The power supply voltage VIN is also connected to the output module through the eleventh switch tube M11, and the control end of the eleventh switch tube M11 is connected to the fifth node E between the seventh switch tube M7 and the second transistor Q2. When the circuit is started, the ninth current I9 is ​​generated in the branch composed of the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6.

[0055] In some embodiments, the parameters of the first transistor Q1 and the second transistor Q2 are the same; the turn-on voltages of the seventh switch tube M7 and the eleventh switch tube M11 are the same.

[0056] Continue to refer Figure 3 The output module 240 of this embodiment includes a seventh resistor R7 and a twelfth switch tube M12. In the output module 240, one end of the seventh resistor R7 is connected to the current output end of the eleventh switch tube M11, and the other end of the seventh resistor R7 is grounded. The current input end of the twelfth switch tube M12 is connected to the current output end of the fifth switch tube M5, the current output end of the twelfth switch tube M12, and the control end of the twelfth switch tube M12 is connected to the current output end of the eleventh switch tube M11, and the current input end of the twelfth switch tube M12 is used to output the comparison voltage VOUT.

[0057] In some embodiments, the current capability of the twelfth switch tube M12 is greater than the current capability of the fifth switch tube M5 .

[0058] Continue to refer Figure 3 The startup module 210 of this embodiment includes a first resistor R1, a sixth switch tube M6 and a tenth switch tube M10. In the startup module 210, one end of the first resistor R1 is connected to the current output end of the first switch tube M1, and the other end of the first resistor R1 is grounded. The power supply voltage VIN is connected to the current output end of the third switch tube M3 through the sixth switch tube M6. The control end of the tenth switch tube M10 is connected to the control end of the sixth switch tube M6 and connected to the current output end of the first switch tube M1, the current input end of the tenth switch tube M10 is connected to the output end of the first operational amplifier A1, and the current output end of the tenth switch tube M10 is grounded.

[0059] In some embodiments, the resistance of the first resistor R1 is greater than or equal to 1 MΩ, and the resistance of the seventh resistor R7 is greater than or equal to 1 MΩ.

[0060] In some embodiments, the seventh switch transistor M7 is an NMOS transistor, and the eleventh switch transistor M11 is a PMOS transistor. The first transistor Q1 and the second transistor Q2 are NPN transistors. 。 The third transistor Q3 and the fourth transistor Q4 are PNP transistors. The first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4, the fifth switch tube M5, the sixth switch tube M6, the eighth switch tube M8, the ninth switch tube M9, and the tenth switch tube M10 are all PMOS tubes or PNP transistors. The twelfth switch tube M12 is an NMOS tube or an NPN transistor.

[0061] exist Figure 3In the embodiment shown, when the voltage difference between the power supply voltage VIN and the second input voltage V2 is greater than the preset value, the eleventh switch tube M11 and the twelfth switch tube M12 are turned on, and the comparison voltage VOUT is at a low level. When the voltage difference between the power supply voltage VIN and the second input voltage V2 is less than the preset value, the eleventh switch tube M11 and the twelfth switch tube M12 are turned off, and the comparison voltage VOUT is at a high level. In some embodiments, the preset value is set to I8×R8, where I8 is the current flowing through the eighth resistor R8, and I8 is a zero temperature coefficient current, and R8 is a zero temperature coefficient resistor. In some embodiments, the ninth current I9 is ​​set to be less than 0.1μA.

[0062] Next, based on Figure 3 The circuit structure, working principle and working process of the power supply voltage comparison circuit of the embodiment are described in detail.

[0063] After the circuit starts to be powered on, the voltage of the first node A is pulled down through the first resistor R1, that is, at this time, the control terminal voltage of the sixth switch tube M6 and the control terminal voltage of the tenth switch tube M10 are both pulled down, and the sixth switch tube M6 and the tenth switch tube M10 are both turned on. The turned-on sixth switch tube M6 will pull up the base voltage of the first transistor Q1 and the second transistor Q2, so the first transistor Q1 and the second transistor Q2 are turned on. At this time, the control terminal voltages of the first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4 and the fifth switch tube M5 are pulled down through the first transistor Q1, and the first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4 and the fifth switch tube M5 are turned on. At this time, the fourth switch tube M4 pulls up the voltage of the second node B, and the seventh switch tube M7 is turned on. At the same time, the tenth switch tube M10 after being turned on pulls down the control terminal voltage of the eighth switch tube M8 and the ninth switch tube M9, so the eighth switch tube M8 and the ninth switch tube M9 are turned on. At this time, the emitter voltage of the third triode Q3 and the fourth triode Q4 is pulled up through the eighth switch tube M8, and the control terminal voltage of the third triode Q3 and the fourth triode Q4 is always pulled down, so the third triode Q3 and the fourth triode Q4 are turned on. At this time, the first current I1 is generated in the branch composed of the first switch tube M1 and the first resistor R1, and because the first resistor R1 is designed to be a resistor with a large resistance (such as a resistance greater than or equal to 1MΩ), the voltage of the first node A is pulled up by the first switch tube M1 at this time, and the sixth switch tube M6 and the tenth switch tube M10 are both turned off, which no longer affects the normal operation of the circuit, and the circuit completes the startup process.

[0064] At this time, refer to Figure 3From the circuit structure, it can be seen that the second current I2 is generated in the branch composed of the second switch tube M2 and the first transistor Q1, the third current I3 is generated in the branch composed of the third switch tube M3 and the second resistor R2, and the fourth current I4 flowing to the second node B is generated in the fourth switch tube M4. At the same time, since no current flows through the gate of the eleventh switch tube M11, at this time, the ninth current I9 is ​​generated in the branch composed of the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6. Since the first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4 and the fifth switch tube M5 form a current mirror of 1:1:1:M:1, it can be obtained at this time that M×first current I1=M×second current I2=M×third current I3=fourth current I4. At the same time, according to the attached Figure 3 It can be seen that the voltage across the second resistor R2 is equal to the voltage difference VBE1 between the base and the emitter of the first transistor Q1. Therefore, at this time, the third current I3=VBE1 / R2, that is, at this time, I1=I2=I3=VBE1 / R2, I4=M×VBE1 / R2.

[0065] At the same time, after the third transistor Q3 and the fourth transistor Q4 are turned on, a fifth current I5 is generated in the branch consisting of the third resistor R3, the third transistor Q3 and the fourth resistor R4, and a sixth current I6 is generated in the branch consisting of the fourth transistor Q4 and the fifth resistor R5. At this time, a first voltage VC is generated at the third node C, and a second voltage VD is generated at the fourth node D. Since the fifth current I5 and the sixth current I6 are both small when the circuit is just powered on, the voltage drop across the third resistor R3 is small, and the emitter voltages of the third transistor Q3 and the fourth transistor Q4 are approximately equal. Since the number ratio of the third transistor Q3 to the fourth transistor Q4 is N:1, at this time, the fifth current I5 is approximately equal to N times the sixth current I6, that is, the fifth current I5 is greater than the sixth current I6. Since the resistance values ​​of the fourth resistor R4 and the fifth resistor R5 are equal, it can be obtained that the first voltage VC is greater than the second voltage VD. At this time, the first operational amplifier A1 outputs a low-level voltage, further pulling down the control terminal voltages of the eighth switch tube M8 and the ninth switch tube M9, so the current flowing through the eighth switch tube M8 and the ninth switch tube M9 increases. That is, at this time, the fifth current I5 and the sixth current I6 also increase continuously, so the voltage drop across the third resistor R3 increases continuously, and at this time, the emitter voltage of the third triode Q3 becomes smaller and smaller relative to the emitter voltage of the fourth triode Q4. Since the collector current of the triode is exponentially related to the voltage difference between its base and emitter, the sixth current I6 becomes larger and larger relative to the fifth current I5.

[0066] When the sixth current I6 increases to be greater than the fifth current I5, the first voltage VC is less than the second voltage VD, the first operational amplifier A1 outputs a high-level voltage, and the control terminal voltages of the eighth switch tube M8 and the ninth switch tube M9 are pulled up, so the current flowing through the eighth switch tube M8 and the ninth switch tube M9 decreases, and the sixth current I6 decreases to be less than the fifth current I5. It can be seen that when the circuit is in a stable state, the fifth current I5 is equal to the sixth current I6, and the first voltage VC is equal to the second voltage VD. At this time, according to the attached Figure 3 From the circuit structure, VBE3+VR3=VBE4, where VR3 is the voltage across the third resistor R3, and VBE3 and VBE4 are the voltage differences between the base and emitter of the third transistor Q3 and the fourth transistor Q4, respectively. That is, ,in, is the thermal voltage, is the reverse saturation current, so we can get, That is, at this time, the current flowing through the eighth switch tube M8 is Since the eighth switch tube M8 and the ninth switch tube M9 form a 1:Y current mirror, the seventh current flowing through the ninth switch tube M9 .

[0067] Continue to refer Figure 3 It can be seen that the eighth current flowing out from the second node B . According to the technical common sense in this field, when the first transistor Q1 is turned on and working normally, the voltage difference VBE1 between its base and emitter is a negative temperature coefficient voltage based on a fixed value, and the negative temperature coefficient is usually -1.9, and the thermal voltage VT is a positive temperature coefficient parameter, and the positive temperature coefficient is usually 0.086. Therefore, at this time, the positive and negative temperature coefficients can be offset by adjusting the value of M, the value of Y, the resistance value of the second resistor R2, and the resistance value of the third resistor R3, so that the eighth current I8 is a zero temperature coefficient current. And at this time, while ensuring and When the ratio of remains unchanged, the value of the eighth current I8 can be reduced by increasing the resistance of the second resistor R2 and the third resistor R3. Conversely, the value of the eighth current I8 can be increased by reducing the resistance of the second resistor R2 and the third resistor R3, thereby adjusting the eighth current I8.

[0068] At this time, by Figure 3 As can be seen from the circuit structure, the power supply voltage comparison circuit in this embodiment has three input terminals and one output terminal. Among them, the three input terminals respectively input the power supply voltage VIN (i.e., the first input voltage), the second input voltage V2 and the ground voltage GND, and one output terminal outputs the comparison voltage VOUT. At the same time, it can be seen from the above analysis that the eighth current flowing from the second node B to the input terminal of the second input voltage V2 , so we can get that the voltage of the second node B Since the eighth current I8 is a zero temperature coefficient current and when the eighth resistor R8 is designed as a zero temperature coefficient resistor, the voltage of the second node B (reference voltage VB) is a fixed voltage value that does not change with temperature.

[0069] It is known from the common technical knowledge in this field that for triodes, ,in, is the voltage difference between the base and the emitter of the transistor. At this time, according to the above analysis, a ninth current I9 is ​​generated in the branch consisting of the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6, and since the parameters of the first transistor Q1 and the second transistor Q2 are exactly the same, it can be obtained that:

[0070] ;

[0071] Therefore, ,Right now At this time, since the second current I2 and the thermal voltage VT are fixed values, the second current I2 and the thermal voltage VT can be regarded as constants, and the ninth current I9 and the sixth resistor R6 can be regarded as variables. The sixth resistor R6 can be derived by taking the derivative of both sides of the equation:

[0072] ;

[0073] So we can get:

[0074] ;

[0075] From the above analysis, it can be known that the ninth current I9 decreases as the sixth resistor R6 increases. Therefore, when the second current I2 and the thermal voltage VT are both fixed values, the sixth resistor R6 with a larger resistance value can be selected, so that the ninth current I9 is ​​less than the set current (such as 0.1μA). When the ninth current I9 is ​​less than the set current, that is, when the current flowing through the seventh switch tube M7 is less than the set current, it can be considered that the seventh switch tube M7 is in a just-on state. At this time, the gate-source voltage difference of the seventh switch tube M7 is equal to the turn-on voltage VTH of the MOS tube, so VB-VE=VTH can be obtained, where VB is the voltage of the second node B, VE is the voltage of the fifth node E, and VE is the gate voltage of the eleventh switch tube M11. According to the attached Figure 3From the circuit structure, it can be seen that when the eleventh switch tube M11 is in the on state, VIN-VE=VTH (the turn-on voltages of the seventh switch tube M7 and the eleventh switch tube M11 are the same, both VTH). Therefore, when VIN-VE>VTH, the eleventh switch tube M11 is in the on state, and when VIN-VE<VTH, the eleventh switch tube M11 is in the off state. It is also known that VB-VE=VTH, VB=V2+I8×R8, so it can be obtained that when VIN>V2+I8×R8, that is, V2<VIN-I8×R8, the eleventh switch tube M11 is in the on state, and when V2>VIN-I8×R8, the eleventh switch tube M11 is in the off state.

[0076] Therefore, it can be seen that Figure 3 In the circuit structure, when the difference between the second input voltage V2 and the power supply voltage VIN is greater than I8×R8, the eleventh switch tube M11 is turned on. At this time, since the seventh resistor R7 is designed to be a resistor with a relatively large resistance (such as greater than or equal to 1MΩ), the control terminal voltage of the twelfth switch tube M12 is pulled up, and the twelfth switch tube M12 is turned on. Since the current capacity of the twelfth switch tube M12 is greater than the current capacity of the fifth switch tube M5, the comparison voltage VOUT is pulled down through the twelfth switch tube M12. When the difference between the second input voltage V2 and the power supply voltage VIN is less than I8×R8, the eleventh switch tube M11 is turned off. At this time, the control terminal voltage of the twelfth switch tube M12 is pulled down through the seventh resistor R7, the twelfth switch tube M12 is turned off, and the comparison voltage VOUT is pulled up through the fifth switch tube M5. Therefore, according to the level of the comparison voltage VOUT, the size of the second input voltage V2 relative to the power supply voltage VIN can be determined. At the same time, since the eighth current I8 is a zero temperature coefficient current and the eighth resistor R8 is a zero temperature coefficient resistor, it can be seen that the high and low level switching points of the comparison voltage VOUT are not affected by temperature, thereby improving the accuracy of the power supply voltage comparison circuit.

[0077] From the above analysis, we can see that Figure 3 The power supply voltage comparison circuit of the embodiment realizes direct comparison between the second input voltage V2 and the power supply voltage VIN, saving the number of ports. On the other hand, it eliminates the external resistor voltage divider circuit, simplifies the circuit structure, and reduces the circuit area. At the same time, the high and low level switching points of the output voltage VOUT are not affected by temperature, reducing the error caused by temperature changes and improving the performance and reliability of the circuit under different temperature environments.

[0078] It should be noted that Figure 3The power supply voltage comparison circuit shown in the embodiment is only a preferred circuit structure to achieve the purpose of the present invention. In other embodiments, each circuit module or device may also use other circuit structures that can achieve the same function, and the present application is not limited thereto.

[0079] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A power supply voltage comparison circuit, characterized in that: It includes a startup module, an input module, a comparison module and an output module; The startup module is used to generate a startup signal after the power supply voltage VIN is turned on, and input the startup signal into the input module; The input module is connected to a second input voltage V2, and is used to generate a reference current and a reference voltage VB, and input the reference voltage VB into the comparison module; The comparison module is used to generate a comparison signal according to the power supply voltage VIN and the second input voltage V2, and input the comparison signal into the output module; the output module generates and outputs a comparison voltage VOUT based on the comparison signal; In the input module, the power supply voltage VIN is connected to the startup module and the output module through the first branch of the first current mirror and the fifth branch of the first current mirror respectively; the power supply voltage VIN is also connected to the ground through the second branch of the first current mirror and the first transistor Q1 in sequence; the power supply voltage VIN is also connected to the ground through the third branch of the first current mirror and the second resistor R2 in sequence; the power supply voltage VIN is also connected to the ground through the first branch of the second current mirror and the proportional current source unit in sequence; the power supply voltage VIN is also connected to the second node B through the second branch of the second current mirror and the fourth branch of the first current mirror respectively; the second input voltage V2 is connected to the second node B through the eighth resistor R8, for outputting the reference voltage VB; In the comparison module, the power supply voltage VIN is grounded through the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6 in sequence, and the control end of the seventh switch tube M7 is connected to the second node B, the base of the second transistor Q2 is connected to the base of the first transistor Q1 and connected to the current output end of the third branch of the first current mirror; the power supply voltage VIN is also connected to the output module through the eleventh switch tube M11, and the control end of the eleventh switch tube M11 is connected to the fifth node E between the seventh switch tube M7 and the second transistor Q2; The output module includes a seventh resistor R7 and a twelfth switch tube M12; one end of the seventh resistor R7 is connected to the current output end of the eleventh switch tube M11, and the other end of the seventh resistor R7 is grounded; the current input end of the twelfth switch tube M12 is connected to the current output end of the fifth branch of the first current mirror, the current output end of the twelfth switch tube M12 is grounded, and the control end of the twelfth switch tube M12 is connected to the current output end of the eleventh switch tube M11, and the current input end of the twelfth switch tube M12 is used to output a comparison voltage VOUT.

2. The power supply voltage comparison circuit according to claim 1, characterized in that: The proportional current source unit comprises a first current branch and a second current branch; In the first current branch, the output end of the first branch of the second current mirror is grounded through the third resistor R3, the third transistor Q3 and the fourth resistor R4 in sequence; In the second current branch, the output end of the first branch of the second current mirror is grounded through the fourth transistor Q4 and the fifth resistor R5 in sequence, and the control end of the fourth transistor Q4 is connected to the control end of the third transistor Q3 and grounded.

3. The power supply voltage comparison circuit according to claim 2, characterized in that: The proportional current source unit further includes a first operational amplifier A1; The current output end of the third transistor Q3 is connected to the inverting input end of the first operational amplifier A1, the current output end of the fourth transistor Q4 is connected to the non-inverting input end of the first operational amplifier A1, and the output end of the first operational amplifier A1 is connected to the reference node of the second current mirror.

4. The power supply voltage comparison circuit according to claim 3, characterized in that: The number ratio of the third transistor Q3 to the fourth transistor Q4 is N:1, and N≥2; the resistance values ​​of the fourth resistor R4 and the fifth resistor R5 are equal.

5. The power supply voltage comparison circuit according to any one of claims 1 to 4, characterized in that: When the voltage difference between the power supply voltage VIN and the second input voltage V2 is greater than a preset value, the comparison voltage VOUT is at a low level; when the voltage difference between the power supply voltage VIN and the second input voltage V2 is less than a preset value, the comparison voltage VOUT is at a high level.

6. The power supply voltage comparison circuit according to any one of claims 3 to 4, characterized in that: The first branch of the first current mirror includes a first switch tube M1, the second branch includes a second switch tube M2, the third branch includes a third switch tube M3, the fourth branch includes a fourth switch tube M4, and the fifth branch includes a fifth switch tube M5, and the control end of the first switch tube M1, the control end of the second switch tube M2, the control end of the third switch tube M3, and the control end of the fourth switch tube M4 are connected to the control end of the fifth switch tube M5 and connected to the current output end of the second switch tube M2.

7. The power supply voltage comparison circuit according to claim 6, characterized in that: The first branch of the second current mirror includes an eighth switch tube M8, and the second branch includes a ninth switch tube M9. The control end of the eighth switch tube M8 is connected to the control end of the ninth switch tube M9, and the connection point between the control end of the eighth switch tube M8 and the control end of the ninth switch tube M9 is a reference node of the second current mirror.

8. The power supply voltage comparison circuit according to claim 7, characterized in that: The first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4 and the fifth switch tube M5 form a current mirror of 1:1:1:M:1; the eighth switch tube M8 and the ninth switch tube M9 form a current mirror of 1:Y.

9. The power supply voltage comparison circuit according to claim 7 or 8, characterized in that: When the circuit is started, a ninth current I9 is ​​generated in the branch consisting of the seventh switch tube M7, the second transistor Q2 and the sixth resistor R6.

10. The power supply voltage comparison circuit according to claim 9, characterized in that: The parameters of the first transistor Q1 and the second transistor Q2 are the same; the turn-on voltages of the seventh switch tube M7 and the eleventh switch tube M11 are the same.

11. The power supply voltage comparison circuit according to claim 10, characterized in that: The current capability of the twelfth switch tube M12 is greater than the current capability of the fifth switch tube M5.

12. The power supply voltage comparison circuit according to claim 11, characterized in that: The startup module includes a first resistor R1, a sixth switch tube M6 and a tenth switch tube M10; In the startup module, one end of the first resistor R1 is connected to the current output end of the first switch tube M1, and the other end of the first resistor R1 is grounded; the power supply voltage VIN is connected to the current output end of the third switch tube M3 through the sixth switch tube M6; the control end of the tenth switch tube M10 is connected to the control end of the sixth switch tube M6 and connected to the current output end of the first switch tube M1, the current input end of the tenth switch tube M10 is connected to the output end of the first operational amplifier A1, and the current output end of the tenth switch tube M10 is grounded.

13. The power supply voltage comparison circuit according to claim 12, characterized in that: The resistance value of the first resistor R1 is greater than or equal to 1 MΩ, and the resistance value of the seventh resistor R7 is greater than or equal to 1 MΩ.

14. The power supply voltage comparison circuit according to claim 13, characterized in that: The seventh switch tube M7 is an NMOS tube, and the eleventh switch tube M11 is a PMOS tube; The first transistor Q1 and the second transistor Q2 are NPN transistors; The third transistor Q3 and the fourth transistor Q4 are PNP transistors; The first switch tube M1, the second switch tube M2, the third switch tube M3, the fourth switch tube M4, the fifth switch tube M5, the sixth switch tube M6, the eighth switch tube M8, the ninth switch tube M9, and the tenth switch tube M10 are all PMOS tubes or PNP transistors; The twelfth switch tube M12 is an NMOS tube or an NPN transistor.

15. The power supply voltage comparison circuit according to any one of claims 11 to 14, characterized in that: When the voltage difference between the power supply voltage VIN and the second input voltage V2 is greater than a preset value, the eleventh switch tube M11 and the twelfth switch tube M12 are turned on, and the comparison voltage VOUT is at a low level; When the voltage difference between the power supply voltage VIN and the second input voltage V2 is less than a preset value, the eleventh switch tube M11 and the twelfth switch tube M12 are turned off, and the comparison voltage VOUT is at a high level.

16. The power supply voltage comparison circuit according to claim 15, characterized in that: The preset value is I8×R8, wherein I8 is the current flowing through the eighth resistor R8, I8 is a zero temperature coefficient current, and R8 is a zero temperature coefficient resistor.

17. The power supply voltage comparison circuit according to claim 15, characterized in that: The ninth current I9 is ​​set to be less than 0.1 μA.

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