CN106033243B - Low-power consumption direct-current voltage comparison circuit - Google Patents
Low-power consumption direct-current voltage comparison circuit Download PDFInfo
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- CN106033243B CN106033243B CN201510121663.3A CN201510121663A CN106033243B CN 106033243 B CN106033243 B CN 106033243B CN 201510121663 A CN201510121663 A CN 201510121663A CN 106033243 B CN106033243 B CN 106033243B
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Abstract
The invention provides a low-power consumption direct-current voltage comparison circuit, which comprises an input end and an output end, wherein the output end is used for outputting detection voltage: the first resistor and the fifth resistor are serially connected between the input end and the ground in sequence, and a node connected with the first resistor and the fifth resistor is a first node; the emitter of the first transistor is connected with a power supply through a second resistor, the collector of the first transistor is grounded through a sixth resistor, and the base of the first transistor is connected with the power supply through a ninth resistor; the base electrode of the first transistor is connected with the first node; the collector of the second transistor is connected with a power supply through a seventh resistor, the base is connected with the collector of the first transistor through an eighth resistor, the emitter is grounded through a third resistor, and the resistance value of the seventh resistor is larger than that of the third resistor; the collector of the second transistor is connected to the output terminal. The low-power consumption direct-current voltage comparison circuit can timely detect voltage change, improves system safety, and is low in power consumption and high in reaction speed.
Description
Technical Field
The invention relates to a low-power consumption direct-current voltage comparison circuit.
Background
In a common industrial or civil application circuit system, a system main controller singlechip is powered by a voltage stabilizing circuit, and is usually realized by an LDO circuit (low dropout linear voltage stabilizing circuit) or a DCDC circuit (direct current-direct current conversion circuit), wherein the power supply input is a higher and unstable input voltage VHH (usually 9V,12V or higher), and the output is a stable low voltage value VCC (usually 5V or 3.3V) used by the system singlechip.
When the power supply end of the system fails, such as a power grid fails, the input voltage VHH drops from a normal voltage level to below the minimum input voltage required by the voltage stabilizing circuit because the external power supply voltage is not available, and the working voltage of the system also fails, so that the circuit system does not work. If such a power outage is unexpected, especially when the circuitry is used in relatively important tasks such as gas concentration collection, or valve control, etc., it may be possible to cause loss of sensitive data due to such an abrupt power outage or to carry a potential risk due to the lack of protective action taken if the system is not previously ready when the power outage occurs.
In fact, if the input voltage VHH drops from the beginning to the complete failure of the output of the voltage stabilizing circuit, there is a time interval of several tens to several hundreds of milliseconds (depending on the size of the voltage stabilizing capacitor used by the input and output of the voltage stabilizing circuit and the normal output current of the voltage stabilizing circuit), if the microcontroller of the system can obtain the early warning signal when the input voltage VHH starts to drop, and at the time of several tens to several hundreds of milliseconds before the system voltage has not dropped to the power-off, protection action is timely taken to backup important data into the nonvolatile memory capable of being written quickly, such as NVRAM or ferroelectric memory, so as to prevent the risk of the system.
Disclosure of Invention
The invention aims to solve the technical problems, and provides a low-power consumption direct-current voltage comparison circuit which can quickly respond and output an alarm signal when an input voltage VHH drops below a threshold voltage set by a resistor, so that the safety of a system is ensured.
The invention provides a low-power consumption direct-current voltage comparison circuit, which comprises an input end for inputting an input voltage and an output end for outputting a detection voltage, and further comprises:
the first resistor and the fifth resistor are serially connected between the input end and the ground in sequence, and a node connected with the first resistor and the fifth resistor is a first node;
the emitter of the first transistor is connected with a power supply through a second resistor, the collector of the first transistor is grounded through a sixth resistor, and the base of the first transistor is connected with the power supply through a ninth resistor;
the base electrode of the first transistor is connected with the first node;
the collector of the second transistor is connected with a power supply through a seventh resistor, the base of the second transistor is connected with the collector of the first transistor through an eighth resistor, the emitter of the second transistor is grounded through a third resistor, and the resistance value of the seventh resistor is larger than that of the third resistor;
the collector of the second transistor is connected with the output terminal.
Preferably, the circuit further comprises a fourth resistor, wherein the base electrode of the first transistor is connected with the first node through the fourth resistor;
specifically, the resistance value of the first resistor is set according to the comparison threshold value.
Preferably, the resistance value of the seventh resistor is 10kΩ, and the resistance value of the third resistor is 10Ω.
Preferably, the first transistor is a PNP transistor, and the second transistor is an NPN transistor.
The low-power consumption direct-current voltage comparison circuit can obtain an early warning signal when the input voltage begins to drop, and takes protection action in time by using the time of tens to hundreds of milliseconds before the system is powered off, so that the system safety is improved, and meanwhile, the self power consumption is lower, and the reaction speed is high.
Drawings
FIG. 1 is a circuit block diagram of a low power DC voltage comparison circuit of the present invention;
FIG. 2 is a graph of input voltage versus output sense voltage;
fig. 3 is a partially enlarged view of fig. 2.
Detailed Description
The low-power consumption DC voltage comparison circuit of the present invention is described in detail below with reference to the accompanying drawings. Fig. 1 is a circuit structure diagram of a low-power consumption dc voltage comparing circuit according to the present invention, wherein an output terminal of the circuit is used for inputting an input voltage VHH, an output terminal of the circuit is used for outputting a DETECTION voltage v_detection, a first resistor R1 is used for setting a comparison threshold v_gate of the comparing circuit, and the specific relationship is shown in the following table by adjusting the resistance of the first resistor R1:
| R1(KΩ) | comparison threshold V_GATE (V) |
| 220 | 9.8 |
| 180 | 8.8 |
| 150 | 8 |
| 110 | 7 |
TABLE 1 relation between first resistance and comparison threshold
The first resistor R1 and the fifth resistor R5 are sequentially connected in series between the input end and the grounding end, and a node between the first resistor R1 and the fifth resistor R5 is used as a first node.
The emitter of the first PNP tube Q2 is connected with the power supply V1 through the second resistor R2, the collector is grounded through the sixth resistor R6, and the base is connected with the power supply V1 through the ninth resistor R9.
Meanwhile, a fourth resistor R4 of the base electrode of the first PNP tube Q2 is connected with the first node.
The collector of the second NPN tube Q7 is connected with the power supply V1 through a seventh resistor R7, the emitter is grounded through a third resistor R3, the base is connected with the collector of the first PNP tube Q2 through an eighth resistor R8, the resistance value of the seventh resistor R7 is far greater than that of the third resistor R3, and a node, connected with the seventh resistor, of the collector of the second NPN tube Q7 is used as an output end for outputting a DETECTION signal V_DETECTION.
In this embodiment, the power supply voltage V1 is 5V, the resistance of the fourth resistor R4 is 100deg.OMEGA, the resistance of the fifth resistor R5 is 120KΩ, the resistance of the second resistor R2 is 0Ω, the resistance of the sixth resistor R6 is 10KΩ, the resistance of the eighth resistor R8 is 2KΩ, the resistance of the seventh resistor R7 is 10KΩ, the resistance of the third resistor R3 is 10Ω, the first PNP transistor is a type 2N2907 transistor, and the second NPN transistor is a type 2N2222 transistor.
In this embodiment, since the comparison threshold v_gate is set to 9V, R1 is selected to be 180kΩ.
The principle of the low power consumption dc voltage comparison circuit of the present invention is briefly described below. Since the emitter of the first PNP transistor Q2 is connected to the power supply V1 through the second resistor R2, the collector is grounded through the sixth resistor R6, and the base is connected to the power supply V1 through the ninth resistor R9, an on threshold voltage is formed at the base of the first PNP transistor Q2, which is about 4.3V in this embodiment.
After the input voltage VHH is divided by the first resistor R1, the fifth resistor R5, and the fourth resistor R4, if the voltage at the base of the first PNP transistor Q2 is higher than the on threshold voltage, the first PNP transistor is turned off, so that the voltage at the base of the second NPN transistor Q7 is also close to 0V, the second NPN transistor Q7 is turned off, and the detection voltage v_detecion output from the output terminal is at a high level.
As the input voltage VHH drops, when the voltage at the base of the first PNP transistor Q2 is lower than the turn-on threshold voltage, the first PNP transistor Q2 is turned on rapidly, so the base-emitter voltage difference of the second NPN transistor Q7 is higher than 0.7V, and the second NPN transistor Q7 is turned on, and at this time, the collector-emitter voltage difference is very small, and thus the value of the DETECTION voltage v_detection is determined by the voltage division between the third resistor R3 and the seventh resistor R7, and since the resistance of the third resistor R3 is far smaller than the seventh resistor R7, the DETECTION voltage v_detection is low, and approaches 0V.
Since the input voltage VHH is higher than the threshold value during normal operation, both transistors are in the off state, so that the power consumption of the whole circuit is only consumed by the first resistor R1 and the fifth resistor R5, and the standby power consumption is lower.
Fig. 2-3 are computer simulation waveforms of the circuit, as shown, in operation, the input voltage VHH drops linearly from 12V to about 0 at about 55ms, which is the same as the threshold voltage v_gate, and at about 200 ms. As shown in fig. 2, as the input voltage VHH decreases, the DETECTION voltage v_detection drops to a level equal to the threshold voltage v_gate, which is 8.8V in the present embodiment, and changes from high to low, and the logic level corresponds to a change from 1 to 0. The inversion part is amplified as shown in fig. 3, the whole conversion time is 1.1ms, the dropping amplitude of the input voltage VHH is 8.7846-8.7184 =0.06V in the 1.1ms, and the low-power consumption direct-current voltage comparison circuit has a relatively high reaction speed and can quickly drop corresponding input voltage, and the current of the low-power consumption direct-current voltage comparison circuit of the embodiment is only 39.3 mu A, and the power consumption of the whole circuit is 4.6 mu W, so that the low power consumption is realized.
The low-power consumption direct-current voltage comparison circuit can quickly react when the input voltage VHH drops at the threshold voltage V_GATE, and the output voltage is inverted to be 0 in low level, so that the highest voltage detection of 40V can be supported, the sensitivity is high, the fuzzy transition window of the detected voltage is smaller than 0.1V, the reaction time is smaller than 1ms, the power consumption is smaller than 0.01 mu W, and the low-power consumption direct-current voltage comparison circuit is simple in structure and low in implementation cost.
Claims (5)
1. The utility model provides a low-power consumption direct current voltage comparison circuit, includes the input that is used for inputing input voltage and is used for the output of output detection voltage, its characterized in that still includes:
the first resistor and the fifth resistor are serially connected between the input end and the ground in sequence, and a node connected with the first resistor and the fifth resistor is a first node, wherein the first resistor is used for setting a comparison threshold value of a comparison circuit;
the emitter of the first transistor is connected with a power supply through a second resistor, the collector of the first transistor is grounded through a sixth resistor, and the base of the first transistor is connected with the power supply through a ninth resistor;
the base electrode of the first transistor is connected with the first node;
the collector of the second transistor is connected with a power supply through a seventh resistor, the base of the second transistor is connected with the collector of the first transistor through an eighth resistor, the emitter of the second transistor is grounded through a third resistor, and the resistance value of the seventh resistor is larger than that of the third resistor;
the collector of the second transistor is connected with the output terminal.
2. The low power consumption dc voltage comparison circuit as claimed in claim 1, further comprising a fourth resistor, wherein the base of the first transistor is connected to the first node through the fourth resistor.
3. The low-power consumption direct current voltage comparing circuit according to claim 2, wherein the resistance value of the first resistor is set according to a comparison threshold value.
4. The low-power consumption direct-current voltage comparing circuit according to claim 2, wherein the resistance of the seventh resistor is 10kΩ, and the resistance of the third resistor is 10Ω.
5. The low power consumption dc voltage comparison circuit according to claim 2, wherein the first transistor is a PNP transistor and the second transistor is an NPN transistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510121663.3A CN106033243B (en) | 2015-03-19 | 2015-03-19 | Low-power consumption direct-current voltage comparison circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510121663.3A CN106033243B (en) | 2015-03-19 | 2015-03-19 | Low-power consumption direct-current voltage comparison circuit |
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| CN106033243A CN106033243A (en) | 2016-10-19 |
| CN106033243B true CN106033243B (en) | 2023-09-29 |
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| CN201510121663.3A Active CN106033243B (en) | 2015-03-19 | 2015-03-19 | Low-power consumption direct-current voltage comparison circuit |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108075443B (en) * | 2016-11-14 | 2020-01-03 | 上海三菱电梯有限公司 | Short-circuit protection circuit for high-speed transistor |
| DE102018218000A1 (en) * | 2018-10-22 | 2020-04-23 | Robert Bosch Gmbh | Window comparator and hand machine tool, power tool, charger and / or household appliance with such a window comparator |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5790390A (en) * | 1994-08-05 | 1998-08-04 | Kayser Ventures, Ltd. | Power supply with reduced EMI |
| CN103384436A (en) * | 2013-08-02 | 2013-11-06 | 广州视源电子科技股份有限公司 | Light-emitting diode (LED) backlight constant-current circuit |
| CN204515677U (en) * | 2015-03-19 | 2015-07-29 | 上海贝岭股份有限公司 | A kind of low-power consumption DC voltage compares circuit |
-
2015
- 2015-03-19 CN CN201510121663.3A patent/CN106033243B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5790390A (en) * | 1994-08-05 | 1998-08-04 | Kayser Ventures, Ltd. | Power supply with reduced EMI |
| CN103384436A (en) * | 2013-08-02 | 2013-11-06 | 广州视源电子科技股份有限公司 | Light-emitting diode (LED) backlight constant-current circuit |
| CN204515677U (en) * | 2015-03-19 | 2015-07-29 | 上海贝岭股份有限公司 | A kind of low-power consumption DC voltage compares circuit |
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