CN202798676U - Low-cost DA transmitter switching circuit - Google Patents
Low-cost DA transmitter switching circuit Download PDFInfo
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- CN202798676U CN202798676U CN 201220502738 CN201220502738U CN202798676U CN 202798676 U CN202798676 U CN 202798676U CN 201220502738 CN201220502738 CN 201220502738 CN 201220502738 U CN201220502738 U CN 201220502738U CN 202798676 U CN202798676 U CN 202798676U
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Abstract
The utility model provides a low-cost DA transmitter switching circuit. A PWM signal input interface is connected with a capacitance isolating circuit and uses capacitance isolation to transmit PWM signals. The capacitance isolating circuit is connected with a D/A switching and U/I switching circuit through a signal shaping circuit. The low-cost DA transmitter switching circuit can conveniently and economically applied on products which require transmitting output, and can ensure high performance indexes which are sufficient to satisfy functional need. The low-cost DA transmitter switching circuit is an alternative design of a commonly used digital-to-analog conversion and voltage-current transformation circuit in smart transmitter products applied in an instrument industry.
Description
Technical field
A kind of low-cost DA transmitter change-over circuit of the utility model is applicable to the transmitter series products.
Background technology
In the design of intelligent transducer, usually adopt the D/A conversion to add that the mode of electric current and voltage conversion realizes that digital quantity is greater than the conversion of 4 ~ 20mA electric current.And usually the cost of DAC chip is higher, cheap as: the DAC7512 of TI the DAC of 7513 12BIT such as grade also want tens yuan.Adopting the PWM conversion regime is both economical technology, but for guaranteeing stability and the less ripple of output signal, it is higher that figure place is differentiated in conversion, just requires higher PWM frequency.Common mentality of designing all is to adopt the light-coupled isolation mode, and the response speed of optocoupler is slower, can't guarantee basic performance.In addition, adopt high speed photo coupling, the one, response speed improves limitation, the DA resolution of realization can not be too high; The 2nd, cost is more expensive more than at least 2 times than common optical coupler.
Summary of the invention
The utility model provides low-cost DA transmitter change-over circuit, can make things convenient for to be applied to economically become on the product that send the output requirement, and guarantee enough to satisfy the high performance index of functional need.Digital-to-analogue conversion general in the intelligent transducer series products used of instrument and meter industry and a kind of alternative designs of voltage current transformating circuit.
Above-mentioned purpose of the present utility model is to realize by such technical scheme: a kind of low-cost DA transmitter change-over circuit, and the pwm signal input interface connects the Capacitor apart circuit, adopts Capacitor apart transmission pwm signal; The Capacitor apart circuit connects D/A conversion and U/I change-over circuit by signal transformation circuit.
Described D/A conversion comprises resistance R 3, R4, the R5 that connects successively with the U/I change-over circuit, connects capacitor C 4 between resistance R 3, the R4, connects capacitor C 5 between resistance R 4, the R5; The second order π type filter circuit that described resistance R 3, R4 and capacitor C 4, C5 connect and compose is used for realizing that pwm signal is to the conversion of voltage signal; Resistance R 3, R4 and resistance R 5 realize the conversion of voltage/current simultaneously.
Described signal transformation circuit comprises in the same way device U1, in the same way device U1 contact resistance R1, diode D2.
Described D/A conversion is connected with the U/I change-over circuit to become send output circuit, described change to send output circuit to adopt the imported change of electric current to send chip U2.
Described in the same way device U1 is and door or or door.
A kind of low-cost DA transmitter change-over circuit of the utility model, adopt the Capacitor apart technology, so that the response for the PWM frequency of circuit improves greatly, upper frequency limit only is subject to shaping circuit, be enough to satisfy the requirement of High Performance PWM conversion, and have good transfer linearity degree (linearity error＜0.5%).This circuit is economical and practical, has reduced the cost of DA change-over circuit, has obvious economic worth, can make things convenient for to be applied to economically become on the product that send the output requirement, and guarantee enough to satisfy the high performance index of functional need.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples:
Fig. 1 is the utility model circuit diagram.
Embodiment
As shown in Figure 1, a kind of low-cost DA transmitter change-over circuit, the pwm signal input interface connects Capacitor apart circuit 1, Capacitor apart circuit 1 connects signal transformation circuit 2, signal transformation circuit 2 connects D/A conversion and U/I change-over circuit 3, and the D/A conversion is connected with U/I change-over circuit 3 to become send output circuit 4.
Capacitor apart circuit 1 is used for the DC potential difference of erasure signal source circuit, DA transmission circuit to the impact of circuit working state, and guarantees uncrossed the passing through of PWM input signal.The isolation voltage rank depends on that capacitor C 1, C2's is withstand voltage.
D/A conversion and U/I change-over circuit 3 will be converted to small output current from the pwm signal of signal shaping circuit 2 outputs.
The D/A conversion utilizes resistance R 3, R4 with U/I change-over circuit 3, and capacitor C 4, C5 have consisted of second order π type filter circuit, realizes that pwm signal is to the conversion of voltage signal; The D/A conversion utilizes the parameter of resistance R 3, R4, R5 to realize the conversion of voltage/current with U/I change-over circuit 3.Digital parameters is converted to 40uA ~ 200uA electric current output.For guaranteeing the stable of output current, resistance R 3 ~ R5 should adopt precision resistance.
Become and to send output circuit 4 to be converted to the output of 4 ~ 20mA electric current from the 40uA of D/A conversion and U/I change-over circuit 3 ~ 200uA electric current input.Becoming the U2 that send output circuit 4 adopts the imported special uses such as XTR115, the XTR116 change of electric current of relative low price to send chip.
Claims (5)
1. a low-cost DA transmitter change-over circuit is characterized in that, the pwm signal input interface connects Capacitor apart circuit (1), adopts Capacitor apart transmission pwm signal;
Capacitor apart circuit (1) connects D/A conversion and U/I change-over circuit (3) by signal transformation circuit (2).
2. described a kind of low-cost DA transmitter change-over circuit according to claim 1, it is characterized in that, described D/A conversion comprises resistance R 3, R4, the R5 that connects successively with U/I change-over circuit (3), connects capacitor C 4 between resistance R 3, the R4, connects capacitor C 5 between resistance R 4, the R5;
The second order π type filter circuit that described resistance R 3, R4 and capacitor C 4, C5 connect and compose is used for realizing that pwm signal is to the conversion of voltage signal;
Resistance R 3, R4 and resistance R 5 realize the conversion of voltage/current simultaneously.
3. described a kind of low-cost DA transmitter change-over circuit according to claim 1 is characterized in that described signal transformation circuit (2) comprises in the same way device (U1), in the same way device (U1) contact resistance R1, diode D2.
4. described a kind of low-cost DA transmitter change-over circuit according to claim 1 is characterized in that, described D/A conversion is connected change and send output circuit (4), described change to send the imported change of output circuit (4) employing electric current to send chip U2 with U/I change-over circuit (3).
5. described a kind of low-cost DA transmitter change-over circuit according to claim 3 is characterized in that, described in the same way device (U1) is and door or or door.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220502738 CN202798676U (en) | 2012-09-27 | 2012-09-27 | Low-cost DA transmitter switching circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220502738 CN202798676U (en) | 2012-09-27 | 2012-09-27 | Low-cost DA transmitter switching circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202798676U true CN202798676U (en) | 2013-03-13 |
Family
ID=47825845
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220502738 Expired - Fee Related CN202798676U (en) | 2012-09-27 | 2012-09-27 | Low-cost DA transmitter switching circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202798676U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110707902A (en) * | 2019-09-23 | 2020-01-17 | 清华大学 | Anti-interference circuit of power electronic transformer power module |
-
2012
- 2012-09-27 CN CN 201220502738 patent/CN202798676U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110707902A (en) * | 2019-09-23 | 2020-01-17 | 清华大学 | Anti-interference circuit of power electronic transformer power module |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130313 Termination date: 20160927 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |