CN212723711U - Four-wire isolated 4-20mA current signal output device - Google Patents
Four-wire isolated 4-20mA current signal output device Download PDFInfo
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- CN212723711U CN212723711U CN202021930191.9U CN202021930191U CN212723711U CN 212723711 U CN212723711 U CN 212723711U CN 202021930191 U CN202021930191 U CN 202021930191U CN 212723711 U CN212723711 U CN 212723711U
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Abstract
The utility model relates to a 4-20mA analog signal output technical field specifically discloses a four-wire system isolated form 4-20mA current signal output device, including first 24V power, 3.3V circuit, MCU control circuit, keep apart boost circuit, magnetism isolating circuit, the 5V circuit, the second 24V power, digital analog conversion circuit and current conversion circuit, wherein, first 24V power and 3.3V circuit connection, 3.3V circuit still respectively with MCU control circuit, keep apart boost circuit, magnetism isolating circuit is connected, MCU control circuit is connected with magnetism isolating circuit, keep apart boost circuit and 5V circuit connection, magnetism isolating circuit and digital analog conversion circuit are connected, digital analog conversion circuit still respectively with the 5V circuit, current conversion circuit is connected, second 24V power is still connected to current conversion circuit. The utility model discloses based on magnetism isolation technique, have that speed is high, the low power dissipation, transient state suppression ability is stronger, the volume is littleer, use convenience, the reliability is high, longe-lived, singly organize isolation device advantage such as bidirectional transmission, the cost is more advantageous.
Description
Technical Field
The utility model relates to a 4-20mA analog signal output technical field, more specifically relates to a four-wire system isolated form 4-20mA current signal output device.
Background
At present, in an industrial field, instruments often transmit various information such as pressure, temperature, gas concentration and the like by using 4-20mA signals; common instruments in the industry have a two-wire system and a three-wire system, wherein the two-wire system instrument supplies power through two wires and simultaneously transmits 4-20mA standard signals; the three-wire system is that the positive end of the power supply uses one wire, the positive end of the signal output uses one wire, and the negative end of the power supply and the negative end of the signal share one wire.
The two-wire system and the three-wire system are non-isolated instruments and cannot protect control circuits such as an MCU (microprogrammed control Unit) and the like, and although the four-wire system instruments exist in the market at present, the four-wire system instruments are all designed to be in optical coupling isolation, so that the defects of low transmission response speed, communication delay, unidirectional transmission of a single-group isolation device, high power consumption, low isolation voltage and the like exist.
SUMMERY OF THE UTILITY MODEL
The utility model provides a four-wire system isolated form 4-20mA current signal output device to solve the problem that the four-wire system instrument transmission response speed that exists is slow, communication time delay, singly organize isolation device can only unidirectional transmission, the consumption is big, isolation voltage low grade is not enough among the prior art.
As a first aspect of the utility model, a four-wire isolated 4-20mA current signal output device is provided, which comprises a first 24V power supply, a 3.3V circuit, an MCU control circuit, an isolation booster circuit, a magnetic isolation circuit, a 5V circuit, a second 24V power supply, a digital-to-analog conversion circuit and a current conversion circuit, wherein the first 24V power supply is connected with the 3.3V circuit, the 3.3V circuit is also respectively connected with the MCU control circuit, the isolation booster circuit and the magnetic isolation circuit, the MCU control circuit is connected with the magnetic isolation circuit, the isolation booster circuit is connected with the 5V circuit, the magnetic isolation circuit is connected with the digital-to-analog conversion circuit, the digital-to-analog conversion circuit is also respectively connected with the 5V circuit and the current conversion circuit, the current conversion circuit is also connected with the second 24V power supply, wherein the second 24V power supply and the current conversion circuit form a 4-20mA output circuit.
Further, the first 24V power supply adopts a DC-DC buck voltage stabilization chip to convert 24V voltage into 5.8V voltage;
the 3.3V circuit adopts a low-noise LDO voltage output calibration chip to perform secondary voltage reduction on 5.8V voltage output by the first 24V power supply, and converts the voltage into 3.3V voltage for supplying power to the MCU control circuit and the magnetic isolation circuit;
the isolation boosting circuit converts the 3.3V voltage output by the 3.3V circuit into 5V voltage, and then the 5V voltage is processed by the 5V circuit and then the 5V voltage is output for supplying power to the digital-to-analog conversion circuit;
the magnetic isolation circuit adopts a special digital isolation chip, isolates the high-speed SPI signal output by the MCU control circuit and then uses the high-speed SPI signal for the digital-to-analog conversion circuit;
the digital-to-analog conversion circuit adopts a 12-bit low-power-consumption integrated DAC chip and a three-wire serial interface, and converts the isolated high-speed SPI signal into an analog signal required by the current conversion circuit;
the 4-20mA output circuit is used for converting the analog signal output by the digital-to-analog conversion circuit into a 4-20mA current signal and outputting the 4-20mA current signal, wherein the second 24V power supply is used for supplying power to the current conversion circuit, and the current conversion circuit is used for converting the analog signal into the 4-20mA current signal and outputting the 4-20mA current signal.
Further, the isolation boosting circuit comprises a transformer U5 and an LDO power chip U6, the model number of the transformer U5 is SN6501, and the model number of the LDO power chip U6 is SPX3819M 5.
Further, the magnetic isolation circuit comprises a magnetic isolation chip U1, and the model of the magnetic isolation chip U1 is ADuM 130.
Further, the digital-to-analog conversion circuit comprises a DAC7311 chip U2 and a voltage follower U3, wherein the model of the voltage follower U3 is AD 8605.
Further, the 4-20mA output circuit further comprises a protection circuit and a bridge type reverse connection prevention circuit, wherein the protection circuit comprises a triode Q1 and a surge clamp diode TVS, and the bridge type reverse connection prevention circuit comprises diodes D1, D2, D3 and D4; the current conversion circuit comprises a resistor R3 and a chip U4, wherein the model of the chip U4 is XTR 115.
The utility model provides a four-wire system isolated form 4-20mA current signal output device has following advantage: the device adopts a four-wire system, a power supply loop and a signal loop are independent respectively, an isolation circuit is adopted for separation, two wires are responsible for power supply, and the other two wires are responsible for output current signals; based on the magnetic isolation technology, the device has the advantages of high speed, low power consumption, stronger transient suppression capability, smaller volume, convenience in application, high reliability, long service life, capability of realizing bidirectional transmission of a single-group isolation device and the like, and has more advantages in cost.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
Fig. 1 is a schematic structural diagram of the four-wire isolated 4-20mA current signal output device provided by the present invention.
Fig. 2 is the structural schematic diagram of the isolation boost circuit provided by the present invention.
Fig. 3 is a schematic structural diagram of the magnetic isolation circuit provided by the present invention.
Fig. 4 is a schematic structural diagram of the digital-to-analog conversion circuit provided by the present invention.
Fig. 5 is a schematic structural diagram of the 4-20mA output circuit provided by the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention for achieving the intended purpose of the present invention, the following detailed description will be given with reference to the accompanying drawings and preferred embodiments of the four-wire isolated 4-20mA current signal output device according to the present invention, and its specific embodiments, structures, features and effects thereof. It is to be understood that the embodiments described are only some of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
In this embodiment, a four-wire isolated 4-20mA current signal output device is provided, as shown in fig. 1, including a first 24V power supply 1, a 3.3V circuit 2, an MCU control circuit 3, an isolation boost circuit 4, a magnetic isolation circuit 5, a 5V circuit 6, a second 24V power supply 7, a digital-to-analog conversion circuit 8, and a current conversion circuit 9, where the first 24V power supply 1 is connected to the 3.3V circuit 2, the 3.3V circuit 2 is further connected to the MCU control circuit 3, the isolation boost circuit 4, and the magnetic isolation circuit 5, the MCU control circuit 3 is connected to the magnetic isolation circuit 5, the isolation boost circuit 4 is connected to the 5V circuit 6, the magnetic isolation circuit 5 is connected to the digital-to-analog conversion circuit 8, the digital-to-analog conversion circuit 8 is further connected to the 5V circuit 6 and the current conversion circuit 9, the current conversion circuit 9 is also connected with the second 24V power supply 7, wherein the second 24V power supply 7 and the current conversion circuit 9 form a 4-20mA output circuit.
Specifically, a back-end circuit (a dashed box a) and a front-end circuit (B dashed box B) are two functional modules for isolating the front part and the back part, the back-end circuit (a dashed box a) is composed of a first 24V power supply 1, a 3.3V circuit 2 and an MCU control circuit 3, and the front-end circuit (B dashed box B) is composed of a 5V circuit 6, a second 24V power supply 7, a digital-to-analog conversion circuit 8 and a current conversion circuit 9.
Preferably, the first 24V power supply 1 adopts a DC-DC buck-type voltage stabilizing chip to convert 24V voltage into 5.8V voltage;
the 3.3V circuit 2 adopts a low-noise LDO voltage output calibration chip to perform secondary voltage reduction on the 5.8V voltage output by the first 24V power supply 1, and converts the voltage into 3.3V voltage for supplying power to the MCU control circuit 3 and the magnetic isolation circuit 5;
the isolation booster circuit 4 converts the 3.3V voltage output by the 3.3V circuit 2 into a 5V voltage, and then the 5V voltage is processed by the 5V circuit 6 and then the 5V voltage is output for supplying power to the digital-to-analog conversion circuit 8;
the magnetic isolation circuit 5 adopts a special digital isolation chip to isolate the high-speed SPI signal output by the MCU control circuit 3 and then use the high-speed SPI signal for the digital-to-analog conversion circuit 8;
the digital-to-analog conversion circuit 8 adopts a 12-bit low-power-consumption integrated DAC chip and a three-wire serial interface to convert the isolated high-speed SPI signal into an analog signal required by the current conversion circuit 9;
the 4-20mA output circuit is used for converting the analog signal output by the digital-to-analog conversion circuit 8 into a 4-20mA current signal to be output, and a bridge circuit is formed by 4 diodes, so that the function of preventing the reverse connection of the power supply voltage is realized; the second 24V power supply 7 is used for supplying power to the current conversion circuit 9, and the current conversion circuit 9 is used for converting the analog signal into a 4-20mA current signal and outputting the current signal.
Preferably, as shown in fig. 2, the isolation boost circuit 4 includes a transformer U5 and an LDO power chip U6, the model of the transformer U5 is SN6501, and the model of the LDO power chip U6 is SPX3819M 5; the working principle is that an SN6501 in a transformer U5 drives a primary side of a thin center-tapped transformer from a 3.3V direct-current power supply, a secondary side of the transformer is wound to provide 5V isolation voltage according to the turn ratio of the transformer, the output voltage of an input LDO power chip U6 and an output voltage of an LDO power chip U6 are adjustable, and for the best effect, R4 is required to be larger than 10K omega, and within the range of 22K omega-47K omega, R2=90.9K, R4=30.1K, Vout =1.235 (1+ R2/R4) =4.96V is taken.
Preferably, as shown in fig. 3, the magnetic isolation circuit 5 includes a magnetic isolation chip U1, the model of the magnetic isolation chip U1 is ADuM130, and is responsible for isolating signals sent by the MCU control circuit 3 and then sending the signals to the front end circuit (dashed box B).
Preferably, as shown in fig. 4, the digital-to-analog conversion circuit 8 includes a DAC7311 chip U2 and a voltage follower U3; the DAC7311 chip U2 converts the digital SPI signal into an analog signal; r1 and C3 form a low-pass filter for filtering and filtering high-frequency interference; the model of the voltage follower U3 is AD8605, and the stability of the analog signal is guaranteed.
Preferably, as shown in fig. 5, the 4-20mA output circuit includes a low-pass filter circuit, a follower circuit, a current conversion circuit, a protection circuit and a bridge anti-reverse connection circuit, the protection circuit includes a transistor Q1 and a surge clamp diode TVS, the bridge anti-reverse connection circuit includes diodes D1, D2, D3 and D4; the current conversion circuit 9 comprises a resistor R3 and a chip U4, wherein the model of the chip U4 is XTR 115; the working principle is that the current conversion circuit converts an analog signal output by the voltage follower U3 into a current signal; the triode Q1 can shunt partial current, and the chip U4 is prevented from being heated and damaged due to overload; the surge clamp diode TVS prevents the chip U4 from being damaged by overvoltage; c6 is a filter capacitor for filtering high-frequency interference at two ends of the chip U4; the bridge type reverse connection preventing circuit prevents the damage caused by reverse connection of an external power supply.
The utility model provides a four-wire system isolated 4-20mA current signal output device, adopt the four-wire system, independent power supply circuit and signal circuit separately, adopt the isolation circuit to separate, two lines are responsible for the supply of power, two lines are responsible for the output current signal; based on the magnetic isolation technology, the device has the advantages of high speed, low power consumption, stronger transient suppression capability, smaller volume, convenience in application, high reliability, long service life, capability of realizing bidirectional transmission of a single-group isolation device and the like, and has more advantages in cost.
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments, and although the present invention has been disclosed with the preferred embodiments, it is not limited to the present invention, and any skilled person in the art can make some modifications or equivalent embodiments without departing from the scope of the present invention, but all the technical matters of the present invention are within the scope of the present invention.
Claims (6)
1. A four-wire isolated 4-20mA current signal output device is characterized by comprising a first 24V power supply (1), a 3.3V circuit (2), an MCU control circuit (3), an isolation booster circuit (4), a magnetic isolation circuit (5), a 5V circuit (6), a second 24V power supply (7), a digital-to-analog conversion circuit (8) and a current conversion circuit (9), wherein the first 24V power supply (1) is connected with the 3.3V circuit (2), the 3.3V circuit (2) is also respectively connected with the MCU control circuit (3), the isolation booster circuit (4) and the magnetic isolation circuit (5), the MCU control circuit (3) is connected with the magnetic isolation circuit (5),
the isolation booster circuit (4) is connected with the 5V circuit (6), the magnetic isolation circuit (5) is connected with the digital-to-analog conversion circuit (8), the digital-to-analog conversion circuit (8) is also respectively connected with the 5V circuit (6) and the current conversion circuit (9), the current conversion circuit (9) is also connected with the second 24V power supply (7),
wherein the second 24V power supply (7) and the current conversion circuit (9) form a 4-20mA output circuit.
2. The four-wire isolated 4-20mA current signal output device according to claim 1, wherein the first 24V power supply (1) adopts a DC-DC buck type voltage stabilization chip to convert 24V voltage into 5.8V voltage;
the 3.3V circuit (2) adopts a low-noise LDO voltage output calibration chip to perform secondary voltage reduction on 5.8V voltage output by the first 24V power supply (1) and convert the voltage into 3.3V voltage for supplying power to the MCU control circuit (3) and the magnetic isolation circuit (5);
the isolation booster circuit (4) converts the 3.3V voltage output by the 3.3V circuit (2) into 5V voltage, and then the 5V voltage is processed by the 5V circuit (6) and then the 5V voltage is output for supplying power to the digital-to-analog conversion circuit (8);
the magnetic isolation circuit (5) adopts a special digital isolation chip, isolates the high-speed SPI signal output by the MCU control circuit (3) and then uses the high-speed SPI signal for the digital-to-analog conversion circuit (8);
the digital-to-analog conversion circuit (8) adopts a 12-bit low-power-consumption integrated DAC chip and a three-wire serial interface to convert the isolated high-speed SPI signal into an analog signal required by the current conversion circuit (9);
the 4-20mA output circuit is used for converting an analog signal output by the digital-to-analog conversion circuit (8) into a 4-20mA current signal and outputting the 4-20mA current signal, wherein the second 24V power supply (7) is used for supplying power to the current conversion circuit (9), and the current conversion circuit (9) is used for converting the analog signal into the 4-20mA current signal and outputting the 4-20mA current signal.
3. The four-wire isolated 4-20mA current signal output device according to claim 1, wherein the isolation boosting circuit (4) comprises a transformer U5 and an LDO power chip U6, the model of the transformer U5 is SN6501, and the model of the LDO power chip U6 is SPX3819M 5.
4. The four-wire isolated 4-20mA current signal output device according to claim 1, wherein the magnetic isolation circuit (5) comprises a magnetic isolation chip U1, and the magnetic isolation chip U1 is ADuM 130.
5. The four-wire isolated 4-20mA current signal output device according to claim 1, wherein the digital-to-analog conversion circuit (8) comprises a DAC7311 chip U2 and a voltage follower U3, the voltage follower U3 is AD 8605.
6. The four-wire isolated 4-20mA current signal output device according to claim 1, wherein the 4-20mA output circuit further comprises a protection circuit and a bridge anti-reverse connection circuit, the protection circuit comprises a transistor Q1 and a surge clamp diode TVS, the bridge anti-reverse connection circuit comprises diodes D1, D2, D3 and D4; the current conversion circuit (9) comprises a resistor R3 and a chip U4, wherein the model of the chip U4 is XTR 115.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021930191.9U CN212723711U (en) | 2020-09-07 | 2020-09-07 | Four-wire isolated 4-20mA current signal output device |
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| CN202021930191.9U CN212723711U (en) | 2020-09-07 | 2020-09-07 | Four-wire isolated 4-20mA current signal output device |
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| CN212723711U true CN212723711U (en) | 2021-03-16 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113162433A (en) * | 2021-05-18 | 2021-07-23 | 北京轩宇空间科技有限公司 | Double-output magnetic isolation feedback circuit |
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- 2020-09-07 CN CN202021930191.9U patent/CN212723711U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113162433A (en) * | 2021-05-18 | 2021-07-23 | 北京轩宇空间科技有限公司 | Double-output magnetic isolation feedback circuit |
| CN113162433B (en) * | 2021-05-18 | 2022-12-09 | 北京轩宇空间科技有限公司 | Double-output magnetic isolation feedback circuit |
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