SLYT847 May   2024 DAC161S997 , DAC8551 , TVS3301

 

  1.   1
  2. 1 Introduction
  3. 2 4mA to 20mA transmitter basics
  4. 3 4mA to 20mA transmitter design aspects
  5. 4 Design performance metrics
  6. 5 Transmitter circuit implementations
  7. 6 Dedicated loop converter
  8. 7 Loop transmitter device
  9. 8 MCU integrated DAC
  10. 9 PWM-based DAC
  11. 10Stand-alone low power DAC
  12. 11Implementations Comparison
  13. 12Conclusion
  14. 13Related websites

6 Dedicated loop converter

One approach is to use a DAC such as the DAC161S997 data sheet with an integrated voltage reference and output amplifier. This solution consists of the DAC, a wide-input-voltage LDO and an NPN transistor, as shown in Figure 4. This implementation has 130µA of current consumption and excellent accuracy without calibration. The DAC161S997 has diagnostic functions to detect current-loop errors in case of low supply or high current loads, and signals an error-low current below 4mA.

The design is simple, with a few external components to ensure loop stability and limit inrush current. This approach has a maximum operating temperature of 105°C.

Two-wire 4mA to 20mA transmitter using the DAC161S997. Figure 4 Two-wire 4mA to 20mA transmitter using the DAC161S997.