CN110797851B - Voltage clamping circuit and electronic equipment thereof - Google Patents
Voltage clamping circuit and electronic equipment thereof Download PDFInfo
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- CN110797851B CN110797851B CN201910967292.9A CN201910967292A CN110797851B CN 110797851 B CN110797851 B CN 110797851B CN 201910967292 A CN201910967292 A CN 201910967292A CN 110797851 B CN110797851 B CN 110797851B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
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Abstract
The invention discloses a voltage clamping circuit. The voltage clamp circuit includes: a protected node; the first control end of the switching circuit is connected with the protected node through the first clamping unit; the second control end of the switch circuit is connected with the direct-current voltage through a second clamping unit; the first clamping unit and the second clamping unit have a corresponding relation so that the switch circuit is conducted when the voltage of a protected node is higher than the direct current voltage.
Description
Technical Field
The present invention relates to electronic circuits, and particularly to a voltage clamp circuit and an electronic device using the same.
Background
The voltage clamp circuit is a protection circuit that limits a voltage value within a specific range. Fig. 1 is a conventional dual diode clamp circuit.
As shown in fig. 1, the dual diode clamp consists of two diodes connected in anti-parallel. The forward voltage drop existing in the diode is utilized. Only one diode can be conducted at the same time, and the other diode is in a cut-off state, so that the forward and reverse voltage drop of the protected node Vin is clamped below the forward conduction voltage drop of the diode by 0.5-0.7, and the purpose of protecting the circuit is achieved.
The specific working principle is as follows: when the voltage of the protected node Vin exceeds Vcc +0.7V, the upper diode is turned on. When the voltage of the protected node Vin is less than-0.7V, the diode at the lower side is turned on, so that the voltage at the point is clamped between Vcc +0.7V and-0.7V.
However, for a relatively precise functional circuit such as an ADC input port of a chip, if the input voltage is greater than VCC, the ADC sampling module may operate abnormally or even be damaged. Therefore, it is desirable to provide a suitable voltage clamp circuit to sufficiently meet the requirements of the chip in practical use.
Disclosure of Invention
The invention aims to provide a voltage clamping circuit and electronic equipment thereof, which can solve one or more problems of the voltage clamping circuit in the prior art.
In a first aspect, embodiments of the present invention provide a voltage clamp circuit. The voltage clamp circuit includes:
a protected node; the first control end of the switching circuit is connected with the protected node through the first clamping unit; the second control end of the switch circuit is connected with the direct-current voltage through a second clamping unit; the first clamping unit and the second clamping unit have a corresponding relation so that the switch circuit is conducted when the voltage of a protected node is higher than the direct current voltage.
Further, the first clamping unit is a first diode; the second clamping unit is a second diode and a third diode which are connected in series; the first diode, the second diode and the third diode have the same voltage drop.
Further, the switch circuit is a triode, and the conduction voltage of the triode is equal to the voltage drop of the diode.
Further, the triode is a PNP type triode; the first clamping unit is connected with an emitting electrode of the triode, and the second clamping unit is connected with a base electrode of the triode; and the collector electrode of the triode is grounded.
Further, the device also comprises a first resistor and a second resistor; one end of the first resistor is connected with the first diode and the emitting electrode of the triode, and the other end of the first resistor is connected with the direct-current voltage; one end of the second resistor is connected with the base electrode of the triode, and the other end of the second resistor is grounded.
Further, when the voltage of the protected node is higher than the direct current voltage, the triode is conducted to pull down the voltage of the protected node.
Further, the triode is turned off when the voltage of the protected node is lower than the direct current voltage.
In a second aspect, an embodiment of the present invention provides an electronic device. The electronic device comprises a functional circuit and a voltage clamping circuit as described above; at least one input terminal of the functional circuit is connected to a protected node of the voltage clamping circuit such that the voltage at the input terminal of the functional circuit is clamped below the dc voltage.
The voltage clamping circuit provided by the embodiment of the invention has a simple and reliable circuit structure, can clamp the voltage value of a protected node below a direct current voltage, plays a good protection role on a precise functional circuit, can well meet the use requirement, and has a good application prospect.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a functional block diagram of a regenerative electromotive force bleeder device according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a voltage detection circuit according to an embodiment of the present invention.
Fig. 3 is a schematic diagram 3 of a voltage clamp circuit according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
Referring to fig. 2, fig. 2 is a voltage clamp circuit according to an embodiment of the present invention. The voltage clamp circuit includes: protected node Vin, switching circuit 11, first clamping unit 12 and second clamping unit 13.
Wherein, the first control end of the switch circuit 11 is connected with the protected node through the first clamping unit 12; the second control terminal of the switching circuit is connected to the dc voltage Vcc through the second clamping unit.
The first clamping unit 12 and the second clamping unit 13 have a corresponding relationship therebetween so that the switching circuit is turned on when the voltage of the protected node is higher than the dc voltage.
The specific correspondence depends on the specific structural design of the first clamping unit 12 and the second clamping unit 13 and the specific used switching circuit 11.
Referring to fig. 2, taking the switch circuit 11 as a PNP-type triode as an example, in some embodiments, the first clamping unit is a first diode D1, and the second clamping unit is a second diode D2 and a third diode D3 connected in series.
The first diode D1, the second diode D2 and the third diode D3 have the same voltage drop V1, and the conduction voltage of the triode is equal to the voltage drop of the diodes.
The first clamping unit is connected with an emitting electrode of the triode, and the second clamping unit is connected with a base electrode of the triode; and the collector electrode of the triode is grounded.
Thus, as can be seen from fig. 2, the emitter voltage Ue of the transistor is Vin-V1, the base voltage Ub of the transistor is Vcc-2V1, and the voltage difference between the base and the emitter is Vin-Vcc + V1.
Based on the characteristic of the PNP type triode when being used as a switching tube, the PNP type triode can be determined that when Vin is larger than Vcc, the voltage difference between the base electrode and the emitting electrode is larger than the conduction voltage, and the triode is in the conduction state, so that the voltage value of a protected node is rapidly pulled down, and the voltage clamping effect is achieved.
When Vin is less than or equal to Vcc, the voltage difference between the base electrode and the emitter electrode is less than the conducting voltage, and the triode is in a cut-off state.
In some embodiments, with continued reference to fig. 2, the voltage clamping circuit may further include: a first resistor R1 and a second resistor R2. The reliable operation of the voltage clamping circuit is ensured through the reasonable first resistor and the second resistor.
One end of the first resistor R1 is connected to the first diode D1 and the emitter of the triode, and the other end of the first resistor R1 is connected to the dc voltage Vcc. One end of the second resistor R2 is connected with the base of the triode, and the other end of the second resistor R2 is grounded.
It should be noted that the invention idea of the voltage clamp circuit provided in the embodiment of the present invention is based. Those skilled in the art can easily think that the settings of the switching circuit, the first clamping unit and the second clamping unit are adjusted accordingly, or different types of electronic components are selected, as long as the switching control characteristics shown in fig. 3 can be satisfied. Any voltage clamp circuit capable of implementing the switching control characteristic shown in fig. 3, modified based on the inventive concept disclosed in fig. 2, falls within the scope of the present application.
As shown in fig. 3, when the voltage of the protected node is higher than the dc voltage, the transistor is turned on to pull the voltage of the protected node low, and when the voltage of the protected node is lower than the dc voltage, the transistor is turned off.
The embodiment of the invention also provides the electronic equipment. The electronic device includes functional circuitry, such as an ADC module and a voltage clamp as described above; at least one input end of the functional circuit is connected with the protected node of the voltage clamping circuit, so that the voltage of the input end of the functional circuit is clamped to be lower than the direct current voltage Vcc, and the protection effect on the functional circuit is achieved.
The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the device disclosed by the embodiment, the description is relatively simple because the device corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications are also within the scope of the present invention as defined in the appended claims.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (7)
1. A voltage clamp circuit, comprising:
a protected node;
the first control end of the switching circuit is connected with the protected node through the first clamping unit; the second control end of the switch circuit is connected with the direct-current voltage through a second clamping unit;
the first clamping unit and the second clamping unit have a corresponding relation so that the switch circuit is conducted when the voltage of a protected node is higher than the direct-current voltage; the first clamping unit and the second clamping unit have a corresponding relation, namely the first clamping unit is a first diode; the second clamping unit is a second diode and a third diode which are connected in series;
the first diode, the second diode and the third diode have the same voltage drop.
2. The voltage-clamping circuit of claim 1, wherein the switching circuit is a transistor having a turn-on voltage equal to a voltage drop across the diode.
3. The voltage-clamping circuit of claim 2, wherein the transistor is a PNP-type transistor; the first clamping unit is connected with an emitting electrode of the triode, and the second clamping unit is connected with a base electrode of the triode; and the collector electrode of the triode is grounded.
4. The voltage clamping circuit of claim 3, further comprising a first resistor and a second resistor;
one end of the first resistor is connected with the first diode and the emitter of the triode, and the other end of the first resistor is connected with the direct-current voltage; one end of the second resistor is connected with the base electrode of the triode, and the other end of the second resistor is grounded.
5. The voltage clamp circuit of claim 4, wherein the transistor conducts to pull the voltage of the protected node low when the voltage of the protected node is higher than the DC voltage.
6. The voltage clamping circuit of claim 4, wherein the transistor is turned off when the voltage at the protected node is not greater than the DC voltage.
7. An electronic device comprising a functional circuit and a voltage clamp circuit as claimed in any one of claims 1-6;
at least one input of the functional circuit is connected to the protected node of the voltage clamp circuit such that the voltage at the input of the functional circuit is clamped below the dc voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910967292.9A CN110797851B (en) | 2019-10-11 | 2019-10-11 | Voltage clamping circuit and electronic equipment thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910967292.9A CN110797851B (en) | 2019-10-11 | 2019-10-11 | Voltage clamping circuit and electronic equipment thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110797851A CN110797851A (en) | 2020-02-14 |
| CN110797851B true CN110797851B (en) | 2022-02-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201910967292.9A Active CN110797851B (en) | 2019-10-11 | 2019-10-11 | Voltage clamping circuit and electronic equipment thereof |
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Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001045657A (en) * | 1999-08-03 | 2001-02-16 | Yokogawa Electric Corp | Input signal protective circuit for ic |
| US6560081B1 (en) * | 2000-10-17 | 2003-05-06 | National Semiconductor Corporation | Electrostatic discharge (ESD) protection circuit |
| CN102709900A (en) * | 2012-06-07 | 2012-10-03 | 无锡友达电子有限公司 | Input stage protection circuit |
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| CN110797851A (en) | 2020-02-14 |
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