Texas Instruments has released a reference design for industrial sensors and field transmitters, integrating 4–20 mA current-loop interfacing, wiring protection and adaptive power management.
Texas Instruments has released a reference design for a three-wire field transmitter platform that supports voltage and current output interfaces used in industrial automation. The design demonstrates a 4–20 mA current-loop interface and supports standard industrial signal levels of 4–20 mA, 0–20 mA and 0–10 V. It enables engineers to evaluate transmitter circuitry for connecting sensors and measurement equipment to industrial control systems.
The design integrates a voltage and current transmitter interface with a current-loop protection circuit. Its output stage supports the generation of industrial voltage and current signals, while a pin header provides access to a pulse-width modulation (PWM) interface for controlling the output stage. The header also supplies 3.3 V power to a connected microcontroller, simplifying integration with an external control system.
A low-pass filter processes the microcontroller’s PWM signal before it drives the output stage. This arrangement allows the microcontroller to control the transmitter output through a filtered signal. The design also incorporates current-loop protection and safeguards against incorrect wiring, helping protect the interface when connected to industrial field equipment.
The reference design includes an adaptive power circuit intended to improve power efficiency under different operating conditions. It also provides a Serial Peripheral Interface (SPI) connection for communication with a microcontroller. Target applications include pressure transmitters, level transmitters, temperature transmitters, magnetic-inductive flow meters and industrial voltage and current output modules.
Texas Instruments provides supporting resources for the reference design, including a design guide with verified performance data, bill of materials (BOM), assembly drawing, computer-aided design and engineering (CAD/CAE) files, Gerber files, printed circuit board (PCB) layout and schematic. The fully assembled board is intended for testing and performance validation and is not available for sale.
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