A single-chip 4-20mA temperature transmitter at embedded world 2015

Last week I wrote about the number of Industrial Communication Solutions supported by MSP430 microcontrollers (MCUs), the most popular among them being the 4-20 mA current loop. We will be showcasing this solution at the embedded world tradeshow in Germany this week. So what exactly is the 4-20 mA solution?

The current solutions can be either 2-wire current loops that provides the communication channel and power to the field transmitter or the 3-wire current loops that have a separate power line not associated directly with the 4-20mA current loop. In this kind of communication, the resolution is by voltage controlled current source and the total current budget for 2-wire field transmitter is less than 3-3.5mA. This makes the ultra-low-power MCUs extremely suitable for 2-wire communication loop solutions. 


Many solutions use external ADCs, Op Amps, and DACs to achieve the current loop solution as shown below : 
However integration of signal conditioning and current control have significant benefits as compared to discrete solutions. TI's single-chip 4-20mA temperature transmitter solution features an ultra-low-power MSP430F2274 MCU is such a solution that:
• provides full turnkey solution for RTD temperature transmitter over current loop
• provides single chip cost effective system solution
• provides for simplified board designs

TI Design:  TIDA-00247
This complete solution features :
• Single-chip 4-20mA and RTD solution
• RTD signal conditioning with integrated OpAmp
• 4-20mA modulation of external transistor circuit established by PWM using 16-Bit Timer
• Less than 1mA system current operation
• 12-Bit resolution of output 4-20mA signal
• Full software solution
This is good for the following industrial applications:
• Factory automation and process control
• Sensors and field transmitters
• Building automation
If you're lucky enough to be at embedded world 2015, check out more details at the TI Booth!