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PRODUCT HIGHLIGHTS. 1. The AD693 is a complete monolithic low-level voltage-to- current loop signal conditioner. 2. Precalibrated output zero and span options include 4–20 mA, 0–20 mA, and 12 ± 8 mA in two- and three-wire configurations. 3. Simple resistor programming adds a continuum of ranges to the basic 30 mV and 60 mV input spans. 4.
This design allows the injection of FSK-modulated digital data into the 4- to 20-mA current loop for HART communication. External protection circuitry is deployed in-place for compliance with regulatory IEC61000-4 standards, including EFT, ESD, and surge requirements.
This reference design explains how to develop a 4–20mA current-loop transmitter, analyze its performance, and select the components that meet rigorous industrial requirements. Test data for error analysis, overtemperature characterization data, schematics, and analysis software are provided.
Select a single channel DAC with the required resolution and accuracy for the application. Use an op amp with low offset and low drift to minimize error. Select a low power DAC, op amp, and voltage regulator to establish a total sensor-transmitter quiescent current of less than 4mA.
2 gru 2020 · The 4-20 mA current loop has become the standard for signal transmission and electronic control in most analog control systems. A 4-20mA current loop circuit is shown in Figure 1.
PART I – ALL ABOUT 4-20mA CURRENT LOOPS. DATA COMMUNICATION METHODS – ANALOG VS. DIGITAL. Measurement data can be electrically transmitted from point A to point B using analog or digital meth-ods such as pulse, frequency or RS-232 serial data signaling1 over both wired and wireless data links.
4-20mA CURRENT LOOP EXAMPLE. Start with a 20psig PPT with a null (00) address. The desired configuration is 4mA output for 40 inches water column (1.5psi) and 20mA output for 400 inches water column (15psi). Integrate the pressure readings over a 1 second period to reduce noise.
