CN207677707U - A kind of precisely reliable UART communications level shifting circuit - Google Patents
A kind of precisely reliable UART communications level shifting circuit Download PDFInfo
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- CN207677707U CN207677707U CN201721880558.9U CN201721880558U CN207677707U CN 207677707 U CN207677707 U CN 207677707U CN 201721880558 U CN201721880558 U CN 201721880558U CN 207677707 U CN207677707 U CN 207677707U
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Abstract
The utility model provides a kind of precisely reliable UART communications level shifting circuit, including resistance R1, resistance R2, capacitance C1 and triode Q1；One end of resistance R2 connects 3.3V DC power supplies, the base stage of other end connecting triode Q1；Capacitance C1 is in parallel with resistance R1；The emitter of triode Q1 connects 5V signal input parts, and the collector of triode Q1 connects 3.3V signal output ends.The utility model provides precisely reliable UART and communicates level shifting circuit, by conducting and the cut-off principle of triode, realizes the low transition that high level arrives；Pass through the series capacitance between the base stage and DC power supply of triode, improve triode switch speed, there is peak voltage when triode can effectively be avoided to turn to cut-off state by conducting state, keep the 3.3V high level being converted by 5V high level more precisely and safe, and then ensures that operating voltage is the microcontroller steady operation of 3.3V.
Description
Technical field
The utility model is related to power electronics field, more particularly to a kind of precisely reliable UART communicates level conversion
Circuit.
Background technology
Universal asynchronous receiving-transmitting transmitter (Universal Asynchronous Receiver/Transmitter, referred to as
UART), it is a kind of Universal Serial Bus, is used for asynchronous communication.UART communications are common a kind of communication sides in microcontroller
Formula.With the development of microcontroller, the operating voltage of microcontroller has the plurality of specifications such as 5V, 3.3V, 1.8V.It is logical that microcontroller carries out UART
The voltage of the high level signal of news is generally the operating voltage of microcontroller, i.e. operating voltage is the UART communication letters of the microcontroller of 5V
Number high level voltage be generally exactly 5V.The biography that the high level that the microcontroller that operating voltage is 5V is sent is 3.3V to operating voltage
Input voltage can be caused excessively high when sensor or microcontroller, easily form dash current, operating voltage may be damaged when serious is
The device of 3.3V；Therefore when the microcontroller of two kinds of different operating voltage carries out UART communications, one is needed to realize communication level
The circuit converted mutually.
Voltage between the microcontroller of varying level is converted mutually, and transformed voltage will be accurate as far as possible, if
Transformed voltage is more than the rated maximum that operating voltage is 3.3V devices, is just likely to cause SCM system operation unstable
Fixed, communication abnormality, the abnormal equivalent risk hidden danger of control, or even microcontroller is caused to damage.
Utility model content
To solve the above-mentioned deficiency mentioned in the prior art, the utility model provides a kind of precisely reliable UART communications electricity
Flat conversion circuit, including resistance R1, resistance R2, capacitance C1 and triode Q1；The triode Q1 is NPN type triode；
One end of the resistance R1 connects 3.3V DC power supplies, and the other end of the resistance R1 connects the triode Q1's
Collector；One end of the resistance R2 connects 3.3V DC power supplies, and the other end of the resistance R2 connects the triode Q1's
Base stage, the capacitance C1 are in parallel with the resistance R1；The emitter connection 5V signal input parts of the triode Q1, described three
The collector of pole pipe Q1 connects 3.3V signal output ends.
Further, the resistance value of the resistance R1 and the resistance value of the resistance R2 are 2k Ω.
Further, the capacitance of the capacitance C1 is 0.1nF.
Precisely reliable UART provided by the utility model communicates level shifting circuit, passes through the conducting and cut-off of triode
The low transition that high level arrives may be implemented in principle；Meanwhile passing through the series electrical between the base stage and DC power supply of triode
Hold, improve triode switch speed, peak voltage occurs when triode can effectively be avoided to turn to cut-off state by conducting state,
Keep 3.3V high level signals made of being converted by 5V high level signals more precisely and safe, and then ensures that operating voltage is 3.3V
Microcontroller steady operation.The accurate reliable UART that the utility model embodiment provides communicates level shifting circuit, only includes
One capacitance, a triode, two resistance and a default power supply, the electronic component used is few, simple in structure, cost
It is cheap.
Description of the drawings
In order to illustrate the embodiment of the utility model or the technical proposal in the existing technology more clearly, below will be to embodiment
Or attached drawing needed to be used in the description of the prior art is briefly described, it should be apparent that, the accompanying drawings in the following description is
Some embodiments of the utility model, for those of ordinary skill in the art, in the premise of not making the creative labor property
Under, other drawings may also be obtained based on these drawings.
Fig. 1 is the circuit diagram that precisely reliable UART provided by the utility model communicates level shifting circuit；
Fig. 2 is the utility model embodiment exemplary waveforms；
Fig. 3 is the utility model embodiment test waveform figure.
Reference numeral：
10 5V signal input parts, 20 3.3V signal input parts
Specific implementation mode
It is new below in conjunction with this practicality to keep the purpose, technical scheme and advantage of the utility model embodiment clearer
Attached drawing in type embodiment, the technical scheme in the utility model embodiment is clearly and completely described, it is clear that is retouched
The embodiment stated is the utility model a part of the embodiment, instead of all the embodiments.Based on the implementation in the utility model
Example, the every other embodiment that those of ordinary skill in the art are obtained without creative efforts belong to
The range of the utility model protection.
" first ", " second " and the similar word used in the utility model embodiment be not offered as any sequence,
Quantity or importance, and be only intended to distinguish different component parts.The similar word such as " one end ", " other end ", simply means to
The orientation or positional relationship of showing device or element is to be based on the orientation or positional relationship shown in the drawings, rather than indicate or imply institute
The device or element of finger must have a particular orientation, with specific azimuth configuration and operation.The classes such as " comprising " or "comprising"
Like word mean the element before the word either object cover appear in the word presented hereinafter element or object and its
It is equivalent, and it is not excluded for other elements or object." connection " either the similar word such as " connected " is not limited to physics or machine
The connection of tool, but may include electrical connection, either directly or indirectly.
Fig. 1 is that the accurate reliable UART that the utility model embodiment provides communicates the circuit theory of level shifting circuit
Figure；As shown in Figure 1, precisely reliable UART communicates level shifting circuit, including resistance R1, resistance R2, capacitance C1 and three poles
Pipe Q1；The triode Q1 is NPN type triode；
One end of the resistance R1 connects 3.3V DC power supplies, and the other end of the resistance R1 connects the triode Q1's
Collector；One end of the resistance R2 connects 3.3V DC power supplies, and the other end of the resistance R2 connects the triode Q1's
Base stage, the capacitance C1 are in parallel with the resistance R1；The emitter connection 5V signal input parts 10 of the triode Q1, it is described
The collector connection 3.3V signal output ends 20 of triode Q1.
When it is implemented, as shown in Figure 1, one end of resistance R1 is connected to 3.3V DC power supplies, the other end of resistance R1 connects
It is connected to the collector of triode Q1；One end of resistance R2 is connected to 3.3V DC power supplies, and the other end of resistance R2 is connected to three poles
The base stage of pipe Q1, resistance R2 is for protecting triode Q1, and to prevent, the base stage of triode Q1 is excessive to the electric current of emitter and leads
Cause triode Q1 damages；Capacitance C1 is in parallel with resistance R2, and one end of capacitance C1 is connected to 3.3V DC power supplies, and capacitance C1's is another
One end is connected to the base stage of triode Q1；Capacitance C1 is connected in series between 3.3V DC power supplies and the base stage of triode Q1, energy
Enough effectively improve the switching speed of triode Q1.
The emitter connection 5V signal input parts 10 of triode Q1, it is defeated that the collector of triode Q1 is additionally coupled to 3.3V signals
Outlet 20；5V signal input parts 10 are used to connect the microcontroller that operating voltage is 5V, input 5V high level signals or low level
Signal；3.3V signal output ends 20 are used to connect the microcontroller that operating voltage is 3.3V, export 3.3V high level signals or low
Level signal.Wherein, triode Q1 is NPN type triode.
The accurate reliable UART communications level shifting circuit that the utility model embodiment provides is retouched in concrete operating principle
It states as follows：
When the microcontroller that the microcontroller that operating voltage is 5V is 3.3V to operating voltage sends high level signal, 5V signals
The input of input terminal 10 is 5V high level signals, i.e. the emitter input of triode Q1 is 5V high level signals, triode Q1
Base stage with transmitting interpolar without forward bias voltage, triode Q1 be in cut-off state, the output of 3.3V signal output ends 20 3.3V
High level signal；I.e. when 5V signal input parts 10 input 5V high level signals, 3.3V signal output ends 20 export 3.3V high electricity
Ordinary mail number；
When the microcontroller that the microcontroller that operating voltage is 5V is 3.3V to operating voltage sends low level signal, 5V signals
The input of input terminal 10 is low level signal, i.e. the emitter input of triode Q1 is low level signal, the base of triode Q1
Pole has forward bias voltage with transmitting interpolar, and triode Q1 is in the conduction state, and it is low that 3.3V signal output ends 20 export 3.3V
Level signal；I.e. when 10 input low level signal of 5V signal input parts, 3.3V signal output ends 20 export low level signal.
When due to the forward conduction voltage of the base emitter interpolar of general triode being 0.6V, and triode is by conducting state
Become cut-off state and need the regular hour, therefore when the level voltage that 5V signal input parts 10 input is 2.7V, triode
Q1 ends not yet, and the level of 20 reality output of 3.3V signal output ends will appear the peak voltage more than 3.3V, such as Fig. 2 institutes
Show.Although the time existing for peak voltage is ofer short duration, it is usually no more than 1us, this peak voltage is to operating voltage
3.3V microcontrollers still can form interference and impact, and transmission data may be caused inaccurate；Therefore in 3.3V DC power supplies and three poles
Series capacitance C1 between the base stage of pipe Q1, can effectively improve the switching speed of triode Q1, that is, shorten triode by conducting shape
State becomes the time needed for cut-off state, and then avoids triode by there is peak voltage when conducting state steering cut-off state,
As shown in figure 3, keeping 3.3V high level signals made of being converted by 5V high level signals more precisely and safe.
Preferably, the resistance value of the resistance R1 and the resistance value of the resistance R2 are 2k Ω.
Preferably, the capacitance of the capacitance C1 is 0.1nF.
The accurate reliable UART that the utility model embodiment provides communicates level shifting circuit, passes through the conducting of triode
With cut-off principle, the low transition that high level arrives may be implemented；Meanwhile by being gone here and there between the base stage and DC power supply of triode
Join capacitance, improve triode switch speed, spike occurs when triode can effectively be avoided to turn to cut-off state by conducting state
Voltage keeps the 3.3V high level being converted by 5V high level more precisely and safe, and then ensures that operating voltage is the list of 3.3V
Piece machine steady operation.The accurate reliable UART that the utility model embodiment provides communicates level shifting circuit, only includes one
Capacitance, a triode, two resistance and a default power supply, the electronic component used is few, simple in structure, at low cost
It is honest and clean.
Although more herein used such as triode, capacitance, signal input, signal output, conducting state, cut-off
The terms such as state, switching speed, but it does not preclude the possibility of using other terms.The use of these items is only for more square
Just the essence of the utility model is described and explained；It is construed as any one of the additional limitations all and is and the utility model
What spirit was disagreed.
Finally it should be noted that：The above various embodiments is only to illustrate the technical solution of the utility model, rather than limits it
System；Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should
Understand：It still can be with technical scheme described in the above embodiments is modified, either to which part or whole
Technical characteristic carries out equivalent replacement；And these modifications or replacements, this practicality that it does not separate the essence of the corresponding technical solution are new
The range of each embodiment technical solution of type.
Claims (3)
1. a kind of precisely reliable UART communicates level shifting circuit, it is characterised in that：Including resistance R1, resistance R2, capacitance C1
And triode Q1；The triode Q1 is NPN type triode；
One end of the resistance R1 connects 3.3V DC power supplies, and the other end of the resistance R1 connects the current collection of the triode Q1
Pole；One end of the resistance R2 connects 3.3V DC power supplies, and the other end of the resistance R2 connects the base stage of the triode Q1,
The capacitance C1 is in parallel with the resistance R1；The emitter connection 5V signal input parts (10) of the triode Q1, described three
The collector connection 3.3V signal output ends (20) of pole pipe Q1.
2. precisely reliable UART communicates level shifting circuit according to claim 1, it is characterised in that：The resistance R1's
Resistance value and the resistance value of the resistance R2 are 2k Ω.
3. precisely reliable UART communicates level shifting circuit according to claim 1, it is characterised in that：The capacitance C1's
Capacitance is 0.1nF.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721880558.9U CN207677707U (en) | 2017-12-28 | 2017-12-28 | A kind of precisely reliable UART communications level shifting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721880558.9U CN207677707U (en) | 2017-12-28 | 2017-12-28 | A kind of precisely reliable UART communications level shifting circuit |
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| Publication Number | Publication Date |
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| CN207677707U true CN207677707U (en) | 2018-07-31 |
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ID=62971958
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| CN201721880558.9U Active CN207677707U (en) | 2017-12-28 | 2017-12-28 | A kind of precisely reliable UART communications level shifting circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109560808A (en) * | 2018-12-28 | 2019-04-02 | 南京康派电子有限公司 | A kind of novel UART interface level conversion and multiplex electronics |
| CN110190868A (en) * | 2019-05-28 | 2019-08-30 | 高新兴物联科技有限公司 | Wake-up circuit and IoT device |
-
2017
- 2017-12-28 CN CN201721880558.9U patent/CN207677707U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109560808A (en) * | 2018-12-28 | 2019-04-02 | 南京康派电子有限公司 | A kind of novel UART interface level conversion and multiplex electronics |
| CN110190868A (en) * | 2019-05-28 | 2019-08-30 | 高新兴物联科技有限公司 | Wake-up circuit and IoT device |
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