DC-DC Power Converters Application Guide
Post date:2018-03-15 10:19:04    View: times    
DC-DC Power Modules Application Guide

 

Generalization: The article is to present and analyze the following topics: typical applications of DC-DC power modules, voltage polarity conversion, external filter capacitor connection, over-load and short-circuit protection circuits, parallel and series connection,etc. The proper using methods prolong the converters’ service life and avoid the defects caused by interference, superheat, self-activation, abnormal activation,etc and other irreparable damage.

Key words: DC-DC  DC/DC filter capacitor  module power  power modules  isolated power supply  power distribution   positive power   over-load and short-circuit protection

                                                   

I. General Applications 

SUNYAUN DC-DC Converter can operate well in any conventional circuits without any external components. It realize the isolation between input and output, and provides one or more sets of isolated output power supply, or forms various voltage or polarity power supply circuits (see Fig. 1).
II. Voltage and Polarity Conversion                                


One of the main features of SUNYUAN DC-DC Converter is that the high galvanic isolation, so user can only uses single DC-DC Converter to form various kinds of electric potential difference. If necessary, output positive can be connected with input GND, then the negative of output terminal has a negative voltage. The input terminal and output terminal are isolated, so the connection modes of output terminal has no special requirements. For example, add a single terminal connecting line, then new output emerged in the main power supply or divides into other different DC voltage. (see Fig. 2). 
 III. Wave Filtering

    In using isolated DC-DC Converter in some circuits which are sensitive to noise or ripple wave, user can add the passive LC wave filtering network to the input and output terminals to reduce the ripple wave (see Fig. 3). This circuit configuration model is generally applied in measuring meters, data process and other noise sensitive circuits whicht require to isolate load and noise to avoid filtering or transmitting noise through power supply circuits and GND. External connecting the wave filtering components, especially input and output wave filtering capacitors can reduce the noise and also the output response time will be longer. For response time and noise norm, which is more important, it depends on the users in designing the circuits.

    The self-resonance frequency of wave filtering inductor is greatly higher than the characteristic frequency of DC-DC Converter (the typical value of characteristic frequency from DC-DC Converter is 100KHz). And users be advised the current rated value of inductor should be about two times bigger than that the real current in usage.

    The capacitance value of output wave filtering capacitor should be proper. If the output capacitance value is too big, it may cause activating problems. For each output channel, the max. capacitance value should not be bigger than 10uF in absolute safe and reliable conditions. Generally recommended value 4.7uF. If requires very low ripple wave value, user can connect an inductor in series, the capacitance value of output filtering capacitor is not too big.

The table below lists the recommended values for the inductor and the capacitor in forming the waver filter. The recommended values listed here are to make sure that the input capacitor or output capacitor can be matched to form a π type wave filter and greatly reduce the characteristic frequence. 

 

 

Input Volt.             (V)

Input Filter Inductance Value(uH)

Input Filter Capacitance Value(uF)

Output Vot.(V)

Output Filter Inductance Value

(uH)

Output Filter Capacitance Value(uF)

3.3

33

1.5

3.3

33

1.5

5

47

1.0

5

47

1.0

9

100

1.0

9

100

1.0

12

220

1.0

12

220

1.0

15

330

0.68

15

330

1.0

24

470

0.47

24

470

0.47

48

680

0.18

48

680

0.18



IV. Over-load Protection

Using the series connection of inductance can prevent generating over-current when connecting the power supply. But in normal operating conditions, output circuits have no protection functions for the over-current and short-circuit, so if there exists over-current or short-circuit conditions, the input terminal of DC-DC Converter will generate very heavy current to meet the requirements from the output terminal. If these conditions cannot be adjusted for a long time, the converter will be burnt because of over-heat. Here presents some protection solutions of DC-DC Converter in the case of over-load in the output terminal.

The most simple method is that connecting the fuse in series. The fuse here must have enough capacity to ensure that it will not be damaged by surge current when connecting the power supply (see Fig. 3). Another method is that add a circuit breaker (see Fig.4 , Fig. 5). If there exists intelligent power management system in the input terminal, an electric resistance (to replace the inductor connected in series ) can be connected in series in input terminal to detect the voltage drop coming through, in that case, power management system can function well. The similar circuit can also be used in output terminal to detect its output circuit, but if the power management system is in the input terminal, the detector should be isolated. The temperature of the electric resistance in output terminal can indicate the over-load exist or not and prevent isolation defects of the system.

If the thermal resistors or other heat sensitive devices are close to the electric resistance, the over-load case can be detected. But the temperature of the whole system should be considered to set proper switching rated values for different operating conditions (see Fig. 6).
Note: All the SUNYUAN power modules have the minimum load requirements, generally more than 10%, which can largely improve the reliability of the system. For the unregulated voltage converter, in the light load conditions, the output voltage will rise highly shortly or even in uncertain states, and for the regulated voltage products, the stability will decline when it is lower than the minimum load. If the power modules supply power to optical coupler, state relay, MOS tubes and low power consumption chips, the modules can be regarded as empty load or light load (the power consumption of the module is very low), so in that case a 10% of the power consumption of fake load (electric resistance) should be added to the output terminal to avoid the damage to the circuit which caused by the unregulated voltage and enhance its durability.   

 

V. Output Voltage Regulation and Over-voltage Protection

   The simplest device for the output voltage regulation and over-voltage protection is that the series connection of a linear voltage regulator in the output terminal (see Fig. 7).  Some other application circuits for reference (Fig.8, Fig.9).
 VISeries Connection of DC-DC Converter

  The connection in series of the output terminals from a numbers of DC-DC Converters is allowed, because the output current of converters is isolated, in that case, user only requires to connect the positive of a converter to the negative of another converter (see Fig. 10), in that method some non-standard voltage generate. In that conditions, the total output current after the connections in series should not be more than the current values of the converter with minimum output current. In the series connection of the converters, the switching circuit of every converter is not synchronous, output ripple wave and noise will increase, so users are recommended to add a LC waver filter in output terminal.  
VIIParallel Connection of DC-DC Converter

    When the output power consumption of a single DC-DC Converter cannot meet the requirements, users can connect a number of converters in parallel to achieve much higher output power consumption.

In parallel connection, the same model of DC-DC Converters should be used to get better performance. For example, if output power consumption requires to arrive at 2.5W, the user can connect 2 pieces of 2W DC-DC Converter in parallel or 3 pieces of 1W DC-DC Converter in parallel, but cannot connect 1 piece of 2W converter and 1 piece of 1W converter in parallel. The reason is that the output voltage for different models of converter is not completely the same, so it cannot ensure the real output power consumption of 2W converters is exactly the 2 times of that from 1W converter. In actual use, 2W converter possibly only outputs 1W power consumption, while 1W converter outputs 1.5W power consumption. In parallel connection, even use the same model of DC-DC Converter, not every converter has the same load. The same model of converter has a good match in output voltage, the load of every converter in parallel connection only has 10% difference.     

In parallel connection of DC-DC Converter, users must pay attention that the switching action of every converter may not synchronous. Some matching methods are available: one is that adopts diode isolation which mainly used high voltage output conditions, such as 12V,15V. Because in that conditions, the breakover voltage drop (typical 0.6V) of diode does not have much impact on circuit output, while for 5V, 9V output converter, the power consumption of diode is too high to connect these DC-DC Converters.

Another parallel connection is that connecting an inductor in the output terminal for each DC-DC Converter (see Fig 12 ). Comparing this method with previous methods, this method consumpts less voltage, and a proper inductor is matched with a capacitor can reduce output ripple wave. The table above lists the inductance values for different voltage values, and use these inductors can reduce ripple wave value in the circuit.
In parallel connection, the ripple wave value increase when more converters added, then user can add a filter capacitor in parallel connection output terminal to reduce ripple wave value. The capacitance value of filter capacitor which adds to each output terminal is about 1uF. For example: connecting two pieces of single voltage output DC-DC Converter in parallel, the filter capacitance value for the capacitor between the common positive and 0V should be 2uF.

This method also applies to display window input terminal, and for the values for the filter inductor in parallel connection input terminal and filter capacitor in parallel connection, check the table above for reference.

In conclusion, the parallel connection of DC-DC Converter is only used in some special situations. Using a single high power consumption converter is better than that using DC-DC Converter group in parallel connection. When connecting converters in parallel, the output voltage mismatch degree for every converter should have appropriate ratio. Users are recommended to check the mismatching degree for every converter in full load to guarantee that the mismatching degree is within 1%-2%. Usually using the DC-DC Converter group in parallel connection with 0.9 power consumption ratio, in that method it can ensure consumption safety warranty for each converter. For example, connecting 2 pieces of 2W converter in parallel, the upper limit of output power consumption is 3.6W not 4W. In most cases, three DC-DC Converter are connected in parallel, users should consider that each converter must have much power consumption allowable degree.

Attached file: SUNYUAN DC-DC Converter Application Guide

 
  
Conclusion:

    In process control, automatic control system not only should operate normally in normal operating conditions, but in abnormal working state. Therefore, it requires to check and judge the operating state is normal or not firstly and then to do a selection on the two control systems. DIN ISO C-P-O-S Series products can do the comparison for the two-channel input analog signals, and select the lower or higher signal (high signal selection/ low signal selection) based on the set standard, then process the selected signals through isolated amplification and conversion to achieve the industrial intelligent automation and reduce the financial loss in process control.
Simple and economical analog signal amplifier transmitter: SY U-P-O/SY A-P-O

 
SY series low cost, small size and simple isolation amplifier isolation transmitter is a series of economical products by Shunyuan developed according to the user's different technical requirements for isolation, amplification and conversion of analog signals in different environments of industrial sites. In the project design, the user can isolate, amplify, convert and transmit to the analog quantity,and make judgments for whether need to full isolation to signal input and output between with working power supply,two isolation or non-isolated of the field analyses during the process of transimtter. according to the characteristics of the live signal to choice different specifications, then reduce manufacturing costs greatly , reduce device size and optimize system architectures under the premise of meeting the technical requirements.
Low cost, small size, simple and applicable isolation amplifier isolation transmitter: SY series
1. VI/IV conversion low cost small volume isolation amplifier. New product promotion price:  usd$5.6 / PCS
Product introduction: SY U-P-O series voltage signal and SY A-P-O series current signal isolation amplifier, it is use small size (SIP 8Pin), low cost design. mainly used to solve these conversion problem between non-standard analog quantity and standard analog signal ,such as the problem between sensor and instrument, PLC and DCS: 0.4-2V/0-5V/1-5V/0-10V/0-20mA/4-20mA etc. which have high precision and high linearity features, The 2000VDC isolation voltage between the working power supply and signal channel can control the interference of surge and common mode harmonics in power supply systems. The product is very convenient to use, free of zero point and gain adjustment. It can achieve the simple conversion and amplification function of the industrial field analog signal without external adjustment potentiometer and other components.
Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=89



2. The low cost and small size of displacement potentiometer resistance signal transmitter. New product promotion price:  usd$5.6 / PCS
Product introduction: SY R-P-O series displacement transducer is a low cost, small volume hybrid integrated circuit that converts the displacement resistance signal into a linear standard signal according to the size of change. The transmitter use the input filter, input protection circuit, high-precision voltage-stabilized reference IC power supply circuit, amplification conversion circuit, zero-degree full-scale adjustment circuit and other conversion circuits. The external power supply can be powered by a switching power supply or a linear regulated power supply. it has high precision and linearity (better than 0.05F.S), and commonly used in precision measuring instruments such as built-in electronic rulers and angular displacement signal transmitters.
 
Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=35

3.Two-wire 4-20mA differential signal acquisition conditioner. New product promotion price: usd$7.1/ PCS
Product introduction: SY C-A-P-O series is a two-wire 4-20mA differential signal acquisition and conditioning chip. The internal of IC contains differential signal acquisition, conditioning, and conversion circuitry, The standard input equivalent resistance allows the IC to collect differential signals from the sensor loop to meet the needs of the user's microcontroller to receive signals. (±9 ~ ±15V) Ultra-wide range power supply or single power supply mode, can achieve the required accuracy requirements of the site without any adjustment loop, and realize the transmission and transmission function of the two-wire 4-20mA signal.  
Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=45

4. Two-wire low cost 4-20mA loop feed acquisition conditioner. New product promotion price: usd$7.1 / PCS
Product information:SY 4-20mA-P is a non-isolated two-wire 4-20mA analog signal acquisition conditioner chip with low cost design.The input active 4-20mA current signal can be converted into a passive control signal output to control the two-wire power supply (feed mode) 4-20mA current loop. and acheive the matching of sensor signal acquisition and active load of analog input and output interface, and effectively solved the problem of collecting the active 4-20 mA current signal and the power supply conflict of the two-wire current loop power supply loop receiving port.
The output mode is designed for the two-wire power supply circuit in which the 24VDC and the sampling resistor (two-wire instrument) are connected in series. It is match with these analog input port which commonly used in industrial sites such as the analog input interface board (host computer), PLC, DCS or other instrument.
Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=25&id=109


5.Two-wire passive I/V converter. New product promotion price: usd$8.5 / PCS
Product information:SY 4-20mA-O is a low cost, small size, two-wire passive 4-20mA transform to voltage signal conversion IC that can converts an active 4-20mA signal into a voltage signal output. The IC use two-wire input loop power supply way, which has a unique high-efficiency signal loop stealing technology and needn’t an external working power supply. make the user design more simplify and reduce user wiring costs.The small input equivalent resistance can make IC collect the current signal from the sensor signal output loop, and can achieve a voltage drop of ≤6V when the input 20mA signal is reached , so that can meet the needs of the user to achieve long distance, distortion free transmission conversion of the sensor signal in the no-power field environment.
 

Product introduction:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=42

6.Low cost speed signal acquisition transmitter IC. New product promotion price: usd$8.8 / PCS

Product introduction:SY S-P-O series low cost speed signal acquisition transmitter is a mixed integrated circuit that amplifies the speed sensor signal, sine wave, sawtooth wave signal or tiny pulse signal into a square wave signal which is completely consistent with the input frequency.
It is suitable for the low cost design solutions that convert amplitude, sine wave, etc. into a standard square wave pulse signal. And it is widely used in the detection of motor running speed and the detection of rotating systems such as automotive ABS brakes.
 
Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=28

7. Frequency conversion analog signal FV / FI isolation transmitter. New product promotion price: usd$10/ PCS

 
 
Product introduction:SY F-P-O series frequency signal low cost and small size two isolated transmitter, It is a mixed integrated circuit that converts pulse frequency signals into linear analog signals (FV/FI conversion). Products are widely used in power electronics, wireless data transmission, remote monitoring, medical equipment, industrial automation and other industries.
Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=41

 

8. Pt100, Cu50 thermal resistance signal two isolation transmitter. New product promotion price: usd$10/ PCS
 
Product introduction: SY Z-W series low cost and small size two isolated transmitters, it is designed for low cost design of scene single channel temperature signal acquisition and monitoring, It can converts the temperature signal collected through the RTD sensor into a linear standard analog signal. it is widely used in temperature sensor signal conversion, amplification and distortion-free remote transmission, temperature signal acquisition and transmission of
industrial PLC or DCS system

Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=87

 

9. AC to DC (AC / DC) low cost isolation transmitter. New product promotion price: usd$10 / PCS
 
Product introduction: The SY AC-P-O series is a mixed integrated circuit that converts AC signal acquisition into a linear DC signal. It can convert the 0-1Vrms (50~60HZ) power frequency signal collected by the sensor (AC transformer) into 4-20mA/0-10mA / 0-20mA DC current signal or 0-1V/0-2.5V. /0-5V/0-10V DC voltage signal. IC packaged products can be combined with external AC transformers to form single-phase or multi-phase fully isolated transmitters and achieve 3KV three isolation between signal input and output signals and auxiliary power supply.
The products can widely used in the fields of electromotor or motor safe operation monitoring, remote monitoring of power transmission and distribution, instrumentation and sensor signal transmission and reception, medical equipment safety isolation barrier, industrial automation control etc.

Product information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=35&id=29


 

Industrial field analog signal isolation amplifier, isolation transmitter safety application can reference the bellow technical information:
 
1、 
IC package isolation amplifier isolation transmitter signal and power supply part external protection circuit diagram  
2、 The newest application version of isolation amplifier: field analog signal bandwidth and isolation transmitter frequency response matching technology
 
The Newest low cost & small size two wire passive 4-20mA signal isolation converter developed by SunYuan Technology Introduction:
1、4-20mA (0-20mA) Two-wire analog signal isolator:
      ISOS 4-20mA Series Mini Low Cost 4-20mA Current Loop Isolator IC              

 

  
              


      ISOS 4-20mA  is the smallest in the industry' (7 pin single in line SIP7 Pin) low cost two wire passive current loop 4-20mA isolation IC developed by Shunyuan. This new product is a pre 4-20mA current signal input, and a post analog signal isolation mixed integrated circuit with a 4-20mA output. The internal of IC including a current signal modulation and demodulation circuit, a signal coupling isolation conversion circuit, and so on. The product use the unique Shunyuan technology invention technology of magnetoelectric coupling isolation and high-efficiency loop stealing, which effectively solves the problem of dependence of current signal isolation on the power supply. and achieved high-precision, high-linearity isolated transmission of 4-20mA (0-20mA) signal between industrial field sensors and instrumentation, PLC and DCS. The 7-pin single in line and ultra small (19.5X12.5X9.8mm) standard PCB board design can be embedded in the instrument panel, sensor, PLC and other internal of operation control board, which simplifies the choice of the user system design and reduces the volume and wiring costs.


Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=25&id=52

2.Two wire passive loop 4-20mA signal isolation distributor:
     ISOS 4-20mA-F Series Mini Low Cost 4-20mA Current Loop Isolation




         
              
         
Distributor IC         

              
         ISOS 4-20mA-F is the smallest in the industry' (7 pin single in line SIP7 Pin) low cost two wire passive current loop 4-20mA isolation IC developed by Shunyuan. This new product can supply power to the pre stage two-wire passive sensor or PLC, DCS equipment through the post feed mode, at the same time it can receive 4-20mA current signal from the output of two-wire sensor and other instrumentation equipment. Got a same linear & scale 4-20 mA signal after isolated. ISOS 4-20mA-F use Sunyuan's unique electromagnetic isolation coupling, high-efficiency loop stealing invention technology, The internal including current signal modulation and demodulation circuit, signal coupling isolation conversion circuit, and a high efficiency DC-DC. Boost circuit, etc. DC-DC booster circuit is a two-wire passive sensor or PLC, DCS equipment power distribution 16V ~ 21.5VDC, which facilitates the signal measurement, remote transmission, isolation and other functions of some passive sensors and meet the customer site need without external assistance power supply to achieve long-distance signal transmission and undistorted transmission. The output of IC is designed for a two-wire power supply loop (on-site explosion-proof function) according to 24VDC and sampling resistor (or load resistor) are connected in series. It is also match the analog input port of the active load of the current industrial field analog input interface board (host computer), PLC, DCS. Or other meters .

Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=25&id=109
3、Two-wire passive 4-20mA current loop isolation conditioner:

     ISOS 4-20mA-E Series Mini Low Cost 4-20mA Current Loop Isolation Conditioner IC 
         
         I
ISOS 4-20mA-E is the industry's smallest (7 pin single in line SIP7 Pin) low cost two wire passive current loop 4-20mA isolation IC developed by Shunyuan. This new product can convert an input active 4-20mA current signal into an isolated passive control signal output, controlling a two-wire power supply (explosion-proof) 4-20mA current loop to achieve the sensor signal acquisition matched with the active load of the analog input interface, which effectively solves the problem of signal collision interference between the active 4-20 mA current collected in the field and the receiving port power supply of the two-wire current loop power supply loop. The 7-pin single in line ultra small (19.5X12.5X9.8mm) standard PCB board design can be embedded in the instrument panel, sensor, PLC and other operation control board, which simplifies the choice of user system design and reduces the size and wiring costs. ISOS 4-20mA-E use Shunyuan's unique electromagnetic isolation coupling and high-efficiency loop stealing invention technology, so that the IC does not need independent power supply. The two-wire loop power supply output mode can save the auxiliary power supply and the two power lines, which greatly simplifies the user's design and reduces the their wiring cost.The internal of IC including a current signal modulation and demodulation circuit, a signal coupling isolation conversion circuit etc. The small input equivalent resistance enables the IC to collect the current signal voltage from the sensor output loop to an ultra-wide range (5~32VDC), so that the user can come true the needs of long-distance, distortion-free transmission without external auxiliary power supply.    

Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=25&id=98
4、Passive two-wire voltage signal to 4-20mA isolation transmitter:
      ISOS V-4-20mA series mini low cost two-wire passive V/I conversion power distribution isolation transmitter IC     

 

          
       
 ISOS V-4-20mA is the smallest in the industry' (7 pin single in line SIP7 Pin) low cost two wire passive current loop 4-20mA isolation IC developed by Shunyuan. The IC can provide a set of 5V (3mA) function expansion power supply to supply power for the pre stage device through the post current loop feeding mode, and receive the voltage signal from the output of the pre-stage device. and got the output is 4-20mA. Standard two-wire current signal after the isolation conversion. The 7-pin single in line ultra small (19.5X12.5X9.8mm) standard PCB board design can be embedded in the instrument panel, sensor, PLC and other operation control board, which simplifies the choice of user system design and reduces the size and wiring costs. The internal of product includes a signal modulation and demodulation circuit, a signal coupling isolation conversion circuit, a high-performance DC-DC conversion circuit, and a V/I conversion circuit etc. The output loop has a wide supply voltage range (12-36VDC), high conversion accuracy, and good linearity. The product is very convenient to use. Customers just need to add a small number of peripheral devices at the input end of the product to realize voltage signal distribution, such as voltage sensor, displacement potentiometer, etc., which need to provide power distribution type sensor and bridge (weighing) detection circuit. The internal integrated process and new technology isolation measures enable the device to meet the requirements of 3KVDC insulation voltage and industrial grade wide temperature, humidity, and vibration. Small size and easy to install. It can be placed inside the sensor to directly convert the displacement and angle resistance signals into a standard 4-20 mA signal. The full scale and zero point can be adjusted and calibrated through an external potentiometer by the user. ISOS V-4-20mA use Shunyuan's unique electromagnetic isolation coupling and high-efficiency loop stealing invention technology to achieve accurate isolation and conversion of voltage signals to 4-20mA standard signals. The output of  IC is designed for two-wire power supply loop feed technology with 24VDC and sampling resistor (or load resistor).It is matches the analog input port of analog input interface board (host computer), PLC, DCS or other instrument contains active load which used in industrial fields. The products have IC package on the PCB, DIN35 standard rail installation and PIM panel embedded installation. The DIN rail type installation can realize multi-channel isolation transmission functions such as one-in-one-out, two-in and two-out, three-in and three-out signals. PIM panel embedded intelligent transmission table can realize 4-20mA signal isolation display, alarm control and long-distance distortion-free transmission. Widely used in metallurgical mining, petrochemical, power equipment, medical equipment, industrial automation, new energy facilities and military research, users can choose the right products according to the needs of the site.

 
Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=25&id=51
5、Two-wire passive 4-20mA to voltage signal isolation converter:
      ISO 4-20mA-O Series Two-Wire Passive I/V Conversion Isolation Transmitter IC 

     
         
 ISO 4-20mA-O is the smallest in the industry (12 pin single in line SIP12 Pin) low cost two wire passive current loop 4-20mA to voltage signal isolation converter IC developed by SunYuan. It can make the input active 4-20mA current signal into a voltage signal output. this IC use two-wire input loop power supply mode, and has unique patented technology for high-efficiency signal loop stealing. It does not require external working power supply, which greatly simplifies the user's design process and reduces the cost of field wiring. The internal of module including a current signal modulation and demodulation circuit, a signal coupling isolation conversion circuit, a power supply inverter circuit, a subtraction circuit, a buffer processing output circuit, and so on . The small input equivalent resistance allows the IC to acquire current signals from the sensor signal output loop and achieve a voltage drop of ≤10V when inputting a 20mA signal. and meet the needs of users without the need for external auxiliary power to achieve long-distance, distortion-free transmission of signals. ISO 4-20mA-O is often used for the isolation of 4-20mA current to voltage signals, eliminating the need for an external power supply to make wiring simpler, lower power consumption, lower self-heat (basically no temperature rise), and high reliability. The biggest feature of the item is that it does not require an external auxiliary power supply. It contains a subtraction circuit and an amplifier buffer output circuit. These circuits bring simple and reliable advantages and also have limitations in use. It is isolated and transmitted for the sensor and PLC output 4-20 mA signal. From another definition, it is the transmission of electric power, so there must be power loss inside. This loss is expressed in the product of the input current value and its own input voltage drop. In this case, the 4-20 mA signal source must have the ability to drive a 500 Ω load in order for the two-wire passive 4-20 mA turn to voltage signal isolation converter to make ISO 4-20 mA-O works well. At present, from the practical application experience of industrial sites, most of the field instruments and sensors, PLC\DCS, etc. can meet the 4-20mA signal output and have the ability to drive 500Ω load. In applications of industrial field, some use only one I/V conversion sampling resistor to convert the input current signal into a voltage signal. Although this circuit is simple, it is not practical. Firstly, when the actual meaning is zero signal, there will be a zero current flowing through the sampling resistor. If the input current is converted to the maximum 5V voltage according to the 4~20mA input analysis, the zero point happens to be 1V. When this 1V is sufficient in the MCU resources, it can be subtracted by the microcontroller software. But in this case, the useful voltage will leave 5-1=4VDC instead of 5VDC. Because of  the maximum input voltage of the microcontroller A/D is the supply voltage of the microcontroller, this voltage is usually 5 VDC. Therefore, it is troublesome to deal with such a simple input conversion circuit, and in order to achieve the number of A/D conversion bits, the cost of the chip is increased. A simple way to solve the above problem is to configure a subtraction and buffer processing circuit composed of an operational amplifier before the input of the single-chip microcomputer. Increasing this level of circuit can make the processing of the zero point more convenient, without consuming the internal resources of the single-chip microcomputer, especially the single-chip microcomputer. When the A/D interface is used to accept such a zero signal and the input is not zero voltage value, the resources of the A/D conversion bit number can be all applied to the useful signal.

  
Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=25&id=48
6、Pt100/Cu50 two-wire passive type temperature signal loop isolation transmitter:
     ISO Z-W-O1 Series Two-Wire Passive Thermal Resistance Signal Isolation Transmitter IC

 


       
ISO Z-W-O1 is the smallest in the industry (12 pin single in line IC packaing) Low cost passive two-wire 4-20mA loop-powered RTD signal isolation transmitter. The product is mainly used for the acquisition, isolation and transmission of Pt10 / Pt100 / Pt1000 or Cu50/Cu100 three-wire, four-wire or two-wire temperature sensor signals. This new product converts the temperature signal collected by the RTD sensor into a linear proportional standard 4-20mA current signal output. The product use the unique electromagnetic isolation mode of Sunyuan Technology and the patented technology of high-efficiency post-feeding technology. It can realize the accurate isolation and conversion of the thermal resistance temperature signal to the 4~20mA standard signal without independent power supply, and it is directly match with various types analog input ports of nstrument (such as PLC, DCS system, etc.). The product is designed as a low cost, small form factor standard SIP12Pin flame retardant IC package. The internal of IC includes signal modulation and demodulation circuit, signal coupling isolation conversion circuit, high-performance DC-DC boost circuit, signal zero point, full-scale calibration circuit and thermal resistance linearization, long-line compensation, and interference suppression circuit. The output loop has a wide supply voltage range (12-36VDC), high conversion accuracy, and good linearity. The full scale and zero point are adjusted and calibrated by the user through an external potentiometer. The internal integrated process structure and new technology isolation measures enable the device to achieve 3000 VDC signal input and output isolation, and can meet the industrial requirements of wide temperature, humidity, vibration and the harsh working environment. ISO ZW-O1 has the characteristics of small size, easy installation and use, and can be directly placed inside the transmitter. Customers only need to add a small number of devices on the periphery to realize high-precision acquisition and isolation of temperature signals of Pt100 and other RTD sensors. This item uses a unique electromagnetic isolation mode and high-performance post-feed technology, so that the IC does not need independent power supply. The two-wire loop power supply output mode can save two power lines, greatly simplifying the user's design and reducing the user wiring cost. The product has an IC package mounted on a small-volume PCB board, a head-type (installation method in the junction box), a PIM panel embedded, and a DIN35 standard rail mounting method. DIN rail mounted packaging can acheive thermal resistance signal signal one-in-one, two-in, two-out, three-in and three-out multi-channel isolation transmission transmission function, PIM panel embedded intelligent transmission table can realize thermal resistance signal isolation display , alarm control and long-distance distortion-free transmission and other functions. It is widely used in metallurgical mining, petrochemical, power equipment, medical equipment, industrial automation, new energy facilities and military research, users can choose the right products according to the needs of the site.

Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=87 

 7、PWM two-wire passive pulse width modulation signal loop isolation 


        transmitter IC 

        ISO D-O1 is the smallest in industry, low power passive PWM pulse width modulation signal isolation to a two-wire 4-20mA transmitter IC. Through the back stage (output interface) current loop feed mode to receive the PWM signal from the output of the pre-stage device, and the corresponding is 4~20mA standard two-wire current signal output after isolation conversion. The product has the characteristics of high conversion precision, good linearity and wide output voltage range (12-36VDC). The integrated process structure and new technology isolation measures enable the device to achieve signal input and output 3000VDC isolation, and meet the industrial requirements of wide temperature, humidity, vibration and harsh working environment. ISO D-O1 use the advanced high-speed optocoupler isolation mode and high-efficiency post-feed technology to achieve accurate isolation and conversion of PWM signals to 4~20mA standard signals. It can be match with the standard analog input ports of various types of instrumentation equipment. Such as: PLC, DCS, FCS) The two-wire ultra-small (22.0X11.0X9.0mm) standard PCB board design without working power can simplify the user system design options and reduce installation volume and wiring costs. The product also has an extended function DIN35 standard rail mounting and PIM panel display embedded mounting. The DIN rail mounted packaging can come true the multi-channel transmission functions such as one-in-one-out, two-in and two-out, three-in and three-out signals. The PIM panel embedded intelligent transmission table can realize the intelligent function of sensor analog signal isolation display, alarm control and long-distance distortion-free transmission. It is widely used in metallurgical mining, petrochemical, power equipment, medical equipment, industrial automation, new energy facilities and military research, users can customize the right products according to site needs.

Detailed technical information:
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=23&id=117
8、Two-wire passive AC signal intelligent transmitter: ISO NNAC-O1 series AC signal to 4-20mA isolation transmission

 

   
      
        (PIM)DIN1X1 ISO AC-O1 (LED1) is a passive two-wire AC to DC (AC/DC) signal display control isolation transmitter that can be used to a new type of detection device for analog current signals make the isolate AC current or voltage in a linear proportional transmission output standard. The product does not need independent power supply, and integrates display, alarm, isolation and transmission. The output of the product is designed for the two-wire power supply circuit (on-site explosion-proof function) with 24VDC and sampling resistor (or load resistance) connected in series. The commonly matched with used analog input interface board (host computer), PLC, DCS or other instrument's analog input and output interfaces to achieve AC voltage and current measurement and control. The internal integrated process and new technology isolation measures enable the device to meet the 3KDC isolation voltage and industrial grade wide temperature, humidity, vibration and harsh environment requirements. (PIM) DIN1X1 ISO AC-O1 (LED1) series products are very convenient to use, adopt standard DIN35 rail mounted packaging installation and panel embedded installation design, which is convenient for users to install and use. The product can realize AC signal to DC without external components. 20mA current loop isolation and signal display function. The item use the two-wire loop power supply output mode, which can save two power cables, simplify the system design scheme, reduce the wiring cost, and supply power through the signal loop of the display control instrument or DCS/FCS system directly, and remotely monitor the power.  electrical automation, instrumentation, rail transit, industrial control intelligence and other fields are widely used. 

Detailed technical information   :
http://www.szsunyuan.com/index.php?m=content&c=index&a=show&catid=57&id=21 
 
Commonly used two-wire passive isolation amplifier, isolation transmitter IC, Sunyuan product technical information download: 
1、4-20mA (0-20mA) Current Loop Isolator IC: ISO 4-20mA 
2、4-20mA two-wire passive I/V conversion isolation transmitter IC: ISO 4-20mA-O series 
3、4-20mA isolation controller (active signal PLC current loop active load) IC: ISO 4-20mA-E
4、Two-wire passive sensor 4-20mA loop isolation distributor IC: ISO 4-20mA-F 
5、Two-wire voltage signal power distribution isolation transmitter IC: ISO V-4-20mA 
 
Commonly used active type (external auxiliary power supply required) isolation amplifier transmitter IC, product selection application data download: 
1、The newest application of isolation amplifier: field analog signal bandwidth and isolation transmitter frequency response matching technology  
2、 
IC package isolation amplifier isolation transmitter signal and power supply part external protection circuit diagram
3、ISO mV series: millivolt-level analog small signal dedicated isolation amplifier IC  
4、
 ISO EM U(A)-P-O-T Series: Zero-point, gain-adjustable analog isolation amplifier isolation transmitter
 
5、 
ISO EM A(U)-P-O-S Series: Input Distribution Isolation Transmitter IC 
6、 ISO EM U(A)-P-O-SD Series: Zero-point gain adjustable input distribution type isolated transmitter IC
 
7、
 ISO EM-U(A)-P-O-O Series: Analog Input Isolation Transmitter with 1 to 2 Output Low Cost Small Size IC mounted Package 
8、
 ISO EM A-P-O Series: 0-±10V Bilateral DC (Voltage/Current) Signal Isolation Amplifier Isolation Transmitter IC 
9、 DIN3 ISOEM U-P-O(A-P-O) Series: Single DIN35 rail mounting packaging low cost small volume isolation transmitter
 
10、
DIN 1X2 ISOEM U(A)-P-O Series: one input and two output DIN35 rail mounting packaging isolation transmitter
 
11、
DIN 2X1 C-P-O Series: 2 input and 1 output analog average isolation transmitter 
.
12、DIN 2X2 ISOEM U(A)-P-O Series: two in two out DIN35 rail mounting isolation transmitter
 
13、
DIN 1X3 ISOEM U(A)-P-O Series:one in three out DIN35 Rail mounting isolation transmitter 
 
14、DIN ISO AC Series: Passive two-wire AC to DC signal isolation transmitter
 
15、
ISO EMH 4-20mA Series: High isolation barrier for track voltage monitoring 
 
16、
ISO F-P-O  Series: Frequency Signal (FV/FI Conversion) Isolated Converter IC
 
17、
ISO U(A)-P-F Series: Analog Signal to Frequency Pulse Signal (V/F) Isolated Transmitter IC
 
18、
ISO EM RMS-P-O Series: Analog True RMS (RMS) Signal Isolation Transmitter Isolation Amplifier 


Product shape and installation method for you reference 

 

 

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