Ahmed Noeman

Sensors measure the processes in factory environments to control the conditions in the overall system through the programmable logic controller (PLC). Typical measurements are temperature, pressure, flow and level. There are different techniques that can be used when designing with flow transmitters but here we look at the PWM technique. In this application note we discuss the question, can the PWM technique be used to achieve features such as fast settling time with very low power consumption?

The loop-powered, 4- to 20-mA output field-transmitter is the industry de facto standard for process automation. PWM to 4-to 20-mA conversion is used in field transmitters for different reasons including:

• Simplicity
• Robustness
• Cost optimization

With new applications demanding higher resolution, lower noise and lower power implementation of the loop transmitter, it represents a challenge for the PWM approach.

Additional resources:

• Explore design resources for flow transmitters including 7 interactive block diagram variants.
• Find sub-system level interactive block diagrams for level transmitters.
• View application specific block diagrams for resistive, capacitive, LVDT and silicon pressure transmitters.