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

11 Implementations Comparison

Table 1 and Table 2 show each of the implementations, their suggested bill of materials (BOM) and their expected performance. The performance numbers are based on limited measurements.

Table 1 Design options for a 4mA to 20mA transmitter, suggested BOM and performance (MSPM0 DAC12, PWM using M0, XTR117).
MSPM0 DAC12 PWM using M0 XTR117
BOM MSPM0G, TPS7B69, DAC8740H TPS7A1601, REF3330, TLV2333, DAC8740H XTR117, DAC8551A, REF3525
Compliance (volts) 40 60 40
Resolution (bits) 12 16 16
Linearity (LSBs) 2 <6 8
Effective resolution (bits) 11 13.4 14
Accuracy 1% full scale, 6uA 1% full scale, 6uA 0.7% full scale, 20uA
Current (μA) 425 240 440
Temperature (°C) 125 125 105
Advantages Low cost Low cost, high resolution, low power high resolution
Table 2 Design options for a 4mA to 20mA transmitter, suggested BOM and performance (DAC161S997, DAC8311, AFE881H1).
DAC161S997 DAC8311 AFE881H1
BOM DAC161S997, TPS7A1601, DAC8740H (1) DAC8311, REF3525, OPA391, TPS7B69, DAC8740H AFE88101 (1), REF35125, OPA391, TPS7A1601
Compliance (volts) 60V 40 60
Resolution (bits) 16 14 16
Linearity (LSBs) 5 4 4
Effective resolution (bits) 13.4 13.4 16
Accuracy 0.01%, 1uA 0.15% 0.07%
Current (μA) 130 130 180 (240 w/intREF)
Temperature (°C) 105 125 125
Compliance (volts) Ultra-low power, high resolution, high accuracy Ultra-low power, low cost high resolution and accuracy, low power, low voltage
(1) The DAC8740 has maximum power-down current of 180µA, and about 300µA when active with a crystal oscillator. The AFE881H1 HART modem, however, consumes 10µA on average. Add the corresponding current if enabling HART.