Application of Analog Signal Isolation Amplifier Technology
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画中画广告开始 画中画广告结束 Keywords: Analog signal: 0-10mA/0-20mA/4-20mA/0-5V/0-10V/0-±5V/1-5V etc. Isolation and conversion between input and output.
Description: ISO series isolation amplifier is a hybrid integrated circuit (IC) that isolates and converts analog signals in proportion. It is divided into two categories: active (including auxiliary power supply) type and passive type.
The passive IC contains current signal modulation and demodulation circuit, signal coupling isolation conversion circuit, etc. The very small input equivalent resistance makes the input voltage of the IC reach an ultra-wide range (7.5-32V) to meet the needs of users to achieve long-distance and distortion-free signal transmission without external power supply. The internal ceramic substrate, printed resistor process and new technology isolation measures enable the device to achieve 3KVAC insulation voltage and industrial-grade wide temperature, humidity, vibration and other harsh on-site environment requirements. ISO4-20mA series products are very convenient to use and can achieve 4-20mA current loop isolation or signal one-in-two-out, two-in-two-out and other conversion functions without any external components.
Active IC is a hybrid integrated circuit that integrates a high-isolation DC/DC power supply and a high-performance linear optocoupler on the same chip. In addition to powering the internal amplifier circuit, the chip can also provide two sets of isolated positive and negative DC power supplies and two sets of 5VDC regulated reference sources to the outside (signal input and output ends), which are specially used for external circuit expansion, such as bridge circuits, small signal preamplifier circuits and other user-specific circuits. This series of products has a wide signal bandwidth of 20KHZ, and can isolate, condition and transform 0~±10VDC bidirectional DC signals or 0~5VAC AC signals. The IC is very small and very convenient to use. Only a few external components are needed to realize the (I/I I/V V/I V/V) isolation and transformation functions of analog signals.
Main application areas: analog signal data acquisition, isolated transmission and power supply, industrial field signal isolation transmission and transformation, ground interference suppression, remote distortion-free signal transmission, instrument and sensor signal isolation and transformation. Power equipment and medical instrument safety isolation fence. Product system: ISO 4-20mA series - two-wire passive 4-20mA signal isolation and conditioning IC ISO-Ax-Px-Ox series - DC current signal (I/V I/I) isolation amplifier IC ISO-Ux-Px-Ox series - DC voltage signal (V/I V/V) isolation amplifier IC ISO1001/1002 series————DC bidirectional or AC signal isolation amplifier IC Product features:
Accuracy level: 0.1, 0.2, 0.5 Extremely high linearity (non-linearity <0.2%) within the full range National standard signal: 0-10mA/0-20mA/4-20mA/0-5V/0-10V/0-±5V/1-5V input/output. With low input impedance and high output load capacity 3KV between signal input/output/auxiliary power supply Three-isolation single power supply, can provide users with isolated power supply at the signal input or output Low cost, small size, standard single row SIP12 and dual row DIP24 pin IC package Industrial grade operating temperature range, flame retardant material vacuum potting in accordance with UL-94 standard 1. Overview Signal isolation technology is to make the analog signal not have a current connection across the barrier between the sender and the receiver when it is sent. This allows the difference between the ground or reference level outside the transmitting and receiving ends to be as high as several thousand volts, and prevents loop currents between different ground potentials that may damage the signal. Noise on the signal ground can damage the signal. Isolation can separate the signal to a clean signal subsystem ground, isolating the sensor, instrumentation or control system from the power supply, thereby ensuring the safe, reliable and stable operation of the entire system device. In another application, the electrical connection between the reference levels can isolate a current path that is unsafe for operators or patients. Signal isolation devices rely on no transmitters and receivers to cross the isolation barrier. This device was once used for digital signals, but linearization problems forced analog signal isolation to be achieved using devices such as transformers, optocouplers, capacitors or photocells. Analog signal isolation: In many systems, analog signals must be isolated. The circuit parameters considered for analog signals are completely different from those for digital signals. Analog signals usually have to consider: accuracy or linearity, frequency response, noise, etc. Then there are the requirements for power supply, which requires high isolation, high accuracy, and low noise, especially for the input stage. It should also be noted that the basic accuracy or linearity of the isolation amplifier cannot be improved by the corresponding application circuit, but these circuits can reduce noise and reduce input stage power supply requirements. For the interference of power supply noise, a modulated carrier can be used to make the analog signal cross this barrier. Two-wire passive signal isolation amplifiers such as ISO4-20 simplify analog isolation. The input signal is duty cycle modulated and sent across the barrier in digital form. The output section receives the modulated signal, converts it back to an analog signal and removes the ripple component inherent in the modulation/demodulation process. Another problem with signal isolation is the power consumption required by the input stage of the isolation amplifier, and the input impedance of the isolation amplifier and its own equivalent resistance are the key to the problem. The output stage is usually based on the chassis or ground, and the input stage usually floats on another potential. Therefore, the power supply of the input stage must also be isolated. Usually a single power supply (5V/12V/15V/24V) is used instead of the ideal positive and negative dual power supply. 2. Principle Introduction Through repeated experimental verification, this series of products has achieved the desired purpose.
Illustrations:
 
3. Typical electrical performance indicators:
3. Typical Application Technology Figure 3 is a typical application wiring schematic diagram of the ISO series isolation amplifier, in which the input and output amplifiers are both follower mode. At this time, the overall magnification of the isolation amplifier is 20 times, R1, R2 and W1 are zero adjustment circuits, R1=5.1K R2=2K W1=2K (multi-turn potentiometer).
Signal input amplifier design:
Figure 4 is the input amplifier circuit. When the input amplifier output (21-pin COM terminal) is 0.5V, the output is 5V (when pins 13 and 14 are short-circuited). Input inverting amplifier circuit: Figure 5 is the wiring diagram of the input inverting amplifier circuit, where the gain is: Kin=-R11/R12 R3=R11//R12 For example: when the input Vin is 0~-100mV and the output is 0~5V, you can take: R11=50K R12=10K R13=8.3K Gain: Kin=-50/10=-5 Input non-inverting amplifier circuit: Figure 6 is the wiring diagram of the input non-inverting amplifier circuit, and its gain is: Kin=1+R2/R1
ISO1001 has designed an output amplifier for users. Its principle is shown in Figure 7. FB is the inverting input terminal of the amplifier. When pins 13 and 14 are short-circuited, the output gain Kout=1+33/10=4.3. Since the isolation amplifier part has a gain of 2.35 times, the total gain K=4.3*2.35=10.1. When the COM terminal voltage of the input amplifier does not reach 0.5V, the gain can be adjusted through the output amplifier, as shown in Figure 8. W2 can be 1~100K (multi-turn potentiometer).
4. Typical application examplesApplication example 1: Use an isolation amplifier to directly measure high voltage signalsInput: 0~±100VDC DC voltage signalOutput: 0~±10VDC Isolation signalTake R4= 100K R0=390 W1=200 (multi-turn potentiometer)Take R3=39K W3=10K (multi-turn potentiometer)R1=5.1K R2=2K W2=2K (multi-turn potentiometer)When the input signal is small, the common-mode amplifier circuit in Figure 6 can be used to make the output of the input amplifier (i.e., the COM terminal voltage) between 0.45 and 0.48V, and the rest is the same as Figure 9.
Application Example 2: Measure the differential small signal output by the bridge. See Figure 10 for the wiring diagram Input: 0~±25mV Bridge differential small signal Output: 0~±10VDC Isolation signal A1, A2 and input amplifier form a data amplifier. If R=100K RG=5K, the amplification factor of the data amplifier is Kin=100/5=20. Other circuit components selection: R1=5.1K R2=2K W2=2K (multi-turn potentiometer) R3=39K W3=10K (multi-turn potentiometer) (Figure 10 Application Example 2) 4. Product dimensions and pin description DIP 24-pin package IC size diagram, see Figure 11 DIP 24-pin package IC pin definition diagram, see Figure 12 (Figure 11 DIP24-pin package IC size diagram) (Figure 12 DIP24 package pin definition diagram) SIP 12-pin package IC size and IC pin definition diagram, see Figure 13 Figure 13 SIP12-pin package IC size and pin definition diagram Summary With the rapid development of modern electronic technology, there are many new devices available for technical personnel to develop and design. Through the functional expansion of new devices, many practical new products can be developed, thereby promoting the continuous upgrading of electronic products, and developing towards low cost, small size, multi-function and intelligent development. Shenzhen Shunyuan Technology Co., Ltd.'s ISO series products have leading technologies such as low cost, small size, high precision and multi-function for similar products at home and abroad. It is widely used in circuit designs with greatly different ground potentials in systems such as industrial control, medical equipment, and instrumentation. Each device and process in the entire product circuit is designed for unique system requirements, and the high level of performance integration of new devices enables more complex operations that were previously impossible across the isolation barrier.
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