Voltage comparator circuit

Abstract

The utility model provides a voltage comparator circuit, which comprises a voltage comparison unit, in which a first connecting end of a switching device Q1 is connected with a first power supply end, a second connecting end of the switching device Q1 is connected with a second power supply end through a resistor R3, and a control end of the switching device Q1 is connected with a first voltage input end through a resistor R2; a first connecting end of the switching device Q2 is connected with a second voltage input end through a resistor R1, a second connecting end of the switching device Q2 is connected with an output end of the voltage comparison unit, and a control end of the switching device Q2 is connected with a second connecting end of the switching device Q1 through a resistor R4; one end of the resistor R5 is connected with the output end of the voltage comparison unit, and the other end is connected with the second power supply end; and the signal shaping unit is used for shaping the comparison result output by the voltage comparison unit. Compared with the prior art, a circuit capable of realizing the function of the voltage comparator can be built through a plurality of switching devices and resistors, so that a voltage comparator integrated IC (integrated circuit) can be replaced, and the design cost is further reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit design technical field, especially relate to a voltage comparator circuit. BACKGROUND

[0002] In the product design process, voltage comparators need to be used for logical judgment of the size of two voltages to make corresponding instructions / work modes etc. In the existing design scheme, integrated IC is usually used to complete the function of voltage comparator, please refer to Figure 1 , which is a function diagram of an integrated IC voltage comparator in the prior art. The problems and defects of the prior art scheme are: a. the cost of integrated IC is high, especially for vehicle-grade; b. the working voltage range is narrow, and some voltage comparators only support single-polarity power supply, or the working voltage is only tens of V.

[0003] Therefore, it is necessary to provide a new technical scheme to solve the above problems. CONTENT OF THE UTILITY MODEL

[0004] One of the purposes of the utility model is to provide a voltage comparator circuit, which can realize the function of voltage comparator through a plurality of switching devices and resistors to build a circuit, so as to replace the integrated IC voltage comparator and further reduce the design cost. In addition, the utility model can also support dual power supply and single power supply to realize a larger working voltage range.

[0005] According to one aspect of the utility model, the utility model provides a kind of voltage comparator circuit, it includes: voltage comparison unit, for comparing the size of first voltage V4 and second voltage V3, and the comparison result is output by its output terminal Vo, the voltage comparison unit includes resistance R1, resistance R2, resistance R3, resistance R4, resistance R5, switching device Q1 and switching device Q2, the first connecting end of the switching device Q1 is connected with first power supply end VCC+, its second connecting end is connected with second power supply end VCC- by resistance R3, its control end is connected with first voltage input terminal in+ by resistance R2;The first connecting end of the switching device Q2 is connected with second voltage input terminal in- by resistance R1, its second connecting end is connected with the output terminal Vo of the voltage comparison unit, its control end is connected with the second connecting end of the switching device Q1 by resistance R4;One end of the resistance R5 is connected with the output terminal Vo of the voltage comparison unit, its other end is connected with the second power supply end VCC-;First voltage input terminal in+ is connected with the first voltage V4, second voltage input terminal in- is connected with the second voltage V3;Signal shaping unit, its first connecting end is connected with the first power supply end VCC+, its second connecting end is connected with the second power supply end VCC-, its input terminal is connected with the output terminal Vo of the voltage comparison unit, its output terminal is OUT, and the signal shaping unit is used to shape the comparison result that the voltage comparison unit outputs, and the comparison result after shaping is output by its output terminal OUT.

[0006] Further, the high level of the shaped comparison result is equal to the voltage of the first power supply end VCC+;The low level of the shaped comparison result is equal to the voltage of the second power supply end VCC-.

[0007] Further, when the second voltage V3 is greater than the first voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned on, and the comparison result output by the output terminal Vo of the voltage comparison unit is high level;When the second voltage V3 is less than the first voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned off, and the comparison result output by the output terminal Vo of the voltage comparison unit is low level.

[0008] Further, the first power supply end VCC+ is connected with positive voltage V1, and the second power supply end VCC- is connected with negative voltage V2;Or the first power supply end VCC+ is connected with positive voltage V1, and the second power supply end VCC- is grounded.

[0009] Further, the switch device Q1 is an NPN triode, the first connection end, the second connection end and the control end of the switch device Q1 are the collector, the emitter and the base of the NPN triode respectively; the switch device Q2 is a PNP triode, the first connection end, the second connection end and the control end of the switch device Q2 are the emitter, the collector and the base of the PNP triode respectively; or the switch device Q1 is an NMOS tube, the first connection end, the second connection end and the control end of the switch device Q1 are the drain, the source and the gate of the NMOS tube respectively; the switch device Q2 is a PMOS tube, the first connection end, the second connection end and the control end of the switch device Q2 are the source, the drain and the gate of the PMOS tube respectively.

[0010] Further, the turn-on voltages of the switch device Q1 and the switch device Q2 are consistent.

[0011] Further, the signal shaping unit comprises a resistance R6, a resistance R7 and a switch device Q3, the first connection end of the switch device Q3 is connected with the first power supply end VCC+ through the resistance R7, the second connection end of the switch device Q3 is connected with the second power supply end VCC-, and the control end of the switch device Q3 is connected with the output end Vo of the voltage comparison unit through the resistance R6.

[0012] Further, when the second voltage V3 is greater than the first voltage V4, the switch device Q1 is turned on, the switch device Q2 is turned on, the switch device Q3 is turned on, and the output end OUT of the signal shaping unit outputs the shaped comparison result as a low level; when the second voltage V3 is less than the first voltage V4, the switch device Q1 is turned on, the switch device Q2 is turned off, the switch device Q3 is turned off, and the output end OUT of the signal shaping unit outputs the shaped comparison result as a high level.

[0013] Further, the switch device Q3 is an NPN triode, the first connection end, the second connection end and the control end of the switch device Q3 are the collector, the emitter and the base of the NPN triode respectively; or the switch device Q3 is an NMOS tube, the first connection end, the second connection end and the control end of the switch device Q3 are the drain, the source and the gate of the NMOS tube respectively.

[0014] Further, the signal shaping unit is a totem pole circuit.

[0015] Compared with the prior art, the utility model can build the circuit which can realize the function of voltage comparator through multiple switch devices and resistances, so as to replace the voltage comparator integrated IC, further reduce the design cost. In addition, the utility model can also support dual power supply, single power supply, realize greater working voltage range. BRIEF DESCRIPTION OF DRAWINGS

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0017] Figure 1 This is a functional schematic diagram of a voltage comparator integrated IC in the prior art;

[0018] Figure 2 This is a circuit diagram of a voltage comparator circuit in one embodiment of the present invention.

Detailed Implementation Methods

[0019] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms coupling, connection, linking, and interconnection used herein to indicate electrical connection mean direct or indirect connection. For example, A being connected to B includes both a direct electrical connection between A and B and a connection between A and B via electrical components or circuits.

[0021] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "back", "positive", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] Please refer to Figure 2 As shown, it is a circuit diagram of a voltage comparator circuit in one embodiment of the present invention. Figure 2 The voltage comparator circuit shown includes a voltage comparison unit 210 and a signal shaping unit 220.

[0023] The voltage comparison unit 210 is used for comparing the sizes of the first voltage V4 and the second voltage V3, and outputting the comparison result through the output terminal Vo. The voltage comparison unit 210 comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a switching device Q1 and a switching device Q2. The first connection terminal of the switching device Q1 is connected with the first power supply terminal VCC+, the second connection terminal thereof is connected with the second power supply terminal VCC- through the resistor R3, and the control terminal thereof is connected with the first voltage input terminal in+ through the resistor R2. The first connection terminal of the switching device Q2 is connected with the second voltage input terminal in- through the resistor R1, the second connection terminal thereof is connected with the output terminal Vo of the voltage comparison unit 210, and the control terminal thereof is connected with the second connection terminal of the switching device Q1 through the resistor R4. One end of the resistor R5 is connected with the output terminal Vo of the voltage comparison unit 210, and the other end thereof is connected with the second power supply terminal VCC-. The first voltage input terminal in+ is connected with the first voltage V4, and the second voltage input terminal in- is connected with the second voltage V3. When the second voltage V3 is greater than the first voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned on, and the output terminal Vo of the voltage comparison unit 210 outputs the comparison result as a high level. When the second voltage V3 is less than the first voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned off, and the output terminal Vo of the voltage comparison unit 210 outputs the comparison result as a low level.

[0024] In the specific embodiment shown in the figure, the first power supply terminal VCC+ is connected with a positive voltage (or positive power supply) V1, and the second power supply terminal VCC- is connected with a negative voltage (or negative power supply) V2. In another embodiment, the first power supply terminal VCC+ is connected with the positive voltage V1, and the second power supply terminal VCC- is grounded. Figure 2

[0025] In the specific embodiment shown in the figure, the first power supply terminal VCC+ is connected with a positive voltage (or positive power supply) V1, and the second power supply terminal VCC- is connected with a negative voltage (or negative power supply) V2. In another embodiment, the first power supply terminal VCC+ is connected with the positive voltage V1, and the second power supply terminal VCC- is grounded. Figure 2 In the specific embodiment shown in the figure, the switching device Q1 is an NPN type triode, the first connection terminal, the second connection terminal and the control terminal of the switching device Q1 are the collector, the emitter and the base of the NPN type triode respectively; the switching device Q2 is a PNP type triode, the first connection terminal, the second connection terminal and the control terminal of the switching device Q2 are the emitter, the collector and the base of the PNP type triode respectively. In another embodiment, the switching device Q1 is an NMOS tube, the first connection terminal, the second connection terminal and the control terminal of the switching device Q1 are the drain, the source and the gate of the NMOS tube respectively; the switching device Q2 is a PMOS tube, the first connection terminal, the second connection terminal and the control terminal of the switching device Q2 are the source, the drain and the gate of the PMOS tube respectively. The turn-on voltage of the switching device Q1 and the switching device Q2 is consistent (or equal).

[0026] ​The first connection end of the signal shaping unit 220 is connected with the first power supply end VCC+, the second connection end is connected with the second power supply end VCC-, the input end is connected with the output end Vo of the voltage comparison unit 210, and the output end is OUT. The signal shaping unit 220 is used for shaping the comparison result output by the voltage comparison unit 210 and outputting the shaped comparison result through the output end OUT. The high level of the shaped comparison result is equal to the voltage of the first power supply end VCC+, and the low level of the shaped comparison result is equal to the voltage of the second power supply end VCC-.

[0027] In Figure 2 In the embodiment shown, the signal shaping unit 220 comprises a resistor R6, a resistor R7 and a switching device Q3. The first connection end of the switching device Q3 is connected with the first power supply end VCC+ through the resistor R7, the second connection end is connected with the second power supply end VCC-, and the control end is connected with the output end Vo of the voltage comparison unit 210 through the resistor R6. When the second voltage V3 is greater than the first voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned on, and the switching device Q3 is turned on. The output end OUT of the signal shaping unit 220 outputs the shaped comparison result as a low level (the low level is equal to the voltage of the second power supply end VCC-). When the second comparison voltage V3 is less than the first comparison voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned off, and the switching device Q3 is turned off. The output end OUT of the signal shaping unit 220 outputs the shaped comparison result as a high level (the high level is equal to the voltage of the first power supply end VCC+).

[0028] In Figure 2 In the specific embodiment shown, the switching device Q3 is an NPN type triode, and the first connection end, the second connection end and the control end of the switching device Q3 are the collector, the emitter and the base of the NPN type triode respectively. In another embodiment, the switching device Q3 is an NMOS tube, and the first connection end, the second connection end and the control end of the switching device Q3 are the drain, the source and the gate of the NMOS tube respectively.

[0029] It should be noted that the signal shaping unit 220 can also use other signal shaping circuits in the prior art, for example, a totem pole circuit, as long as it can shape the comparison result output by the voltage comparison unit 210, so that the high level of the shaped comparison result is equal to the voltage of the first power supply end VCC+, and the low level of the shaped comparison result is equal to the voltage of the second power supply end VCC-.

[0030] In order to facilitate understanding of the present application, the working principle of the voltage comparator circuit shown in Figure 2 will be specifically introduced below.

[0031] Wherein, the first power supply end VCC+ is connected with positive voltage V1 (or positive power supply), the second power supply end VCC- is connected with negative voltage (or negative power supply) V2; the first voltage input end in+ is connected with the first voltage V4, the second voltage input end in- is connected with the second voltage V3. When designing, the resistance R1, R2 is configured with small resistance value, the resistance R3, R5 is configured with large resistance value, the triode with Vbe_Q1≈Vbe_Q2≈0.7V (i.e. the opening voltage of triode Q1, Q2 is consistent) is selected, so that Ve_Q1≈V4-0.7V-Ib*R2≈V4-0.7V.

[0032] 1. When the second voltage V3 is greater than the first voltage V4,

[0033] V3>Ve_Q1+0.7V, then the triode Q2 is in amplification state; Ve_Q1≈V4-Vbe_Q1, since V3>V4, V3-Vbe_Q2>V4-Vbe_Q1, i.e. Ve_Q2>Ve_Q1, therefore Ib_Q2=(Ve_Q2-Ve_Q1) / R4>0A, Ic_Q2=β*Ib_Q2, the R5 is configured so that Ic_Q2*R5>Vbe_Q3, so that the triode Q3 is in saturation state, at this time the voltage of the output end OUT is about VCC-.

[0034] 2. When the second voltage V3 is less than the first voltage V4,

[0035] Ve_Q1≈V4-Vbe_Q1, since V3<V4, V3-Vbe_Q2<V4-Vbe_Q1, i.e. Ve_Q1>Ve_Q2, but due to the unidirectional conduction of the emitter and collector of Q2, Ib=0A, therefore the triode Q2 is in cut-off state, i.e. Ic_Q2=0A, the voltage on the resistance R5 is 0V, Vbe_Q3=0V, the triode Q3 is in cut-off state. At this time the voltage of the output end OUT is about VCC+.

[0036] From the above, Figure 2 The voltage comparator circuit shown realizes the voltage comparator function that when V3>V4, the output end OUT is VCC-, and when V3<V4, the output end OUT is VCC+.

[0037] When the power supply voltage is single power supply only V1, GND and VCC- are shorted together, the working logic of the circuit remains consistent with the above logic, but since the emitter voltage of the triode Q1, Q2, Q3 needs to be>0.7V to work normally to enter the switching of saturation / cut-off state, therefore the voltage V1, V3, V4 needs to be>0.7V for the circuit to work normally.

[0038] According to the logical principle, the minimum voltage of the whole circuit is only about 1V (greater than 0.7V) and the maximum voltage is the highest working voltage of the transistor, so the working voltage range of the circuit design is very wide.

[0039] In conclusion, the voltage comparator circuit provided by the utility model uses common types of transistors (or MOS tubes) and resistors to build and can complete the function of the voltage comparator, and the cost is reduced. And the car standard transistor (or MOS tube) and resistor are selected, so the car standard voltage comparator integrated IC can be replaced, and the cost is reduced. The working voltage of the transistor (or MOS tube) can usually reach 40V, or even more than 100V, so the working voltage range of the voltage comparator of the circuit design is wider, and the single power supply can be supported by short-circuiting GND and VCC.

[0040] It should be pointed out that any modification made by the skilled person in the specific embodiment of the utility model does not deviate from the scope of the claims of the utility model. Accordingly, the scope of the claims of the utility model is not limited to the foregoing specific embodiment.

Claims

1. A voltage comparator circuit, characterized in that, It includes: A voltage comparison unit is used to compare the magnitudes of a first voltage V4 and a second voltage V3, and outputs the comparison result through its output terminal Vo. The voltage comparison unit includes resistors R1, R2, R3, R4, and R5, and switching devices Q1 and Q2. The first connection terminal of switching device Q1 is connected to the first power supply terminal VCC+, and its second connection terminal is connected to the second power supply terminal VCC- via resistor R3. Its control terminal is connected to the first voltage input terminal in+ via resistor R2. The first connection terminal of switching device Q2 is connected to the second voltage input terminal in- via resistor R1, and its second connection terminal is connected to the output terminal Vo of the voltage comparison unit. Its control terminal is connected to the second connection terminal of switching device Q1 via resistor R4. One end of resistor R5 is connected to the output terminal Vo of the voltage comparison unit, and the other end is connected to the second power supply terminal VCC-. The first voltage input terminal in+ is connected to the first voltage V4, and the second voltage input terminal in- is connected to the second voltage V3. The signal shaping unit has a first connection terminal connected to the first power supply terminal VCC+, a second connection terminal connected to the second power supply terminal VCC-, an input terminal connected to the output terminal Vo of the voltage comparison unit, and an output terminal OUT. The signal shaping unit is used to shape the comparison result output by the voltage comparison unit and output the shaped comparison result through its output terminal OUT.

2. The voltage comparator circuit according to claim 1, characterized in that, The high level of the comparison result after shaping is equal to the voltage of the first power supply terminal VCC+; The low level of the comparison result after shaping is equal to the voltage of the second power supply terminal VCC-.

3. The voltage comparator circuit according to claim 2, characterized in that, When the second voltage V3 is greater than the first voltage V4, the switching device Q1 is turned on and the switching device Q2 is turned on, and the comparison result output by the output terminal Vo of the voltage comparison unit is high. When the second voltage V3 is less than the first voltage V4, the switching device Q1 is turned on and the switching device Q2 is turned off, and the comparison result output by the output terminal Vo of the voltage comparison unit is low.

4. The voltage comparator circuit according to claim 3, characterized in that, The first power supply terminal VCC+ is connected to a positive voltage V1, and the second power supply terminal VCC- is connected to a negative voltage V2; or The first power supply terminal VCC+ is connected to the positive voltage V1, and the second power supply terminal VCC- is grounded.

5. The voltage comparator circuit according to claim 4, characterized in that, The switching device Q1 is an NPN transistor, and its first connection terminal, second connection terminal, and control terminal are the collector, emitter, and base of the NPN transistor, respectively; the switching device Q2 is a PNP transistor, and its first connection terminal, second connection terminal, and control terminal are the emitter, collector, and base of the PNP transistor, respectively; or The switching device Q1 is an NMOS transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching device Q1 are the drain, source, and gate of the NMOS transistor, respectively; the switching device Q2 is a PMOS transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching device Q2 are the source, drain, and gate of the PMOS transistor, respectively.

6. The voltage comparator circuit according to claim 1, characterized in that, The switching devices Q1 and Q2 have the same turn-on voltage.

7. The voltage comparator circuit according to claim 5, characterized in that, The signal shaping unit includes resistor R6, resistor R7, and switching device Q3. The first connection terminal of the switching device Q3 is connected to the first power supply terminal VCC+ via the resistor R7, its second connection terminal is connected to the second power supply terminal VCC-, and its control terminal is connected to the output terminal Vo of the voltage comparison unit via the resistor R6.

8. The voltage comparator circuit according to claim 7, characterized in that, When the second voltage V3 is greater than the first voltage V4, the switching device Q1, the switching device Q2, and the switching device Q3 are turned on, and the output terminal OUT of the signal shaping unit outputs the shaped comparison result as a low level. When the second voltage V3 is less than the first voltage V4, the switching device Q1 is turned on, the switching device Q2 is turned off, and the switching device Q3 is turned off. The output terminal OUT of the signal shaping unit outputs the shaped comparison result as a high level.

9. The voltage comparator circuit according to claim 8, characterized in that, The switching device Q3 is an NPN transistor, and its first connection terminal, second connection terminal, and control terminal are respectively the collector, emitter, and base of the NPN transistor; or The switching device Q3 is an NMOS transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching device Q3 are the drain, source, and gate of the NMOS transistor, respectively.

10. The voltage comparator circuit according to claim 1, characterized in that, The signal shaping unit is a totem pole circuit.

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