SLVAEW6 December   2020 TPS2661

 

  1.   Trademarks
  2. 1Introduction
  3. 2Protection Required for Current Inputs in Analog Input Modules
    1. 2.1 Over-Current Protection from Miswiring to Field Power Supplies
    2. 2.2 Over-Voltage Protection from Miswiring to Field Power Supplies
  4. 3Typical Discrete Circuit for Protection of Current Input
    1. 3.1 Protection Provided by Discrete Circuit
      1. 3.1.1 Over-Current Protection with Discrete Circuit
      2. 3.1.2 Over-voltage Protection with Discrete Circuit
    2. 3.2 Heating and Temperature Rise with Discrete Circuit
    3. 3.3 Reverse Leakage Current of Zener Diodes and Current Measurement Accuracy
  5. 4TPS26610 for Analog Current Loop Protection
    1. 4.1 Current Input Protection with TPS26610
    2. 4.2 Accurate Current Limiting with TPS26610
    3. 4.3 Leakage Current of TPS26610 and Current Measurement Accuracy
    4. 4.4 Protection from Mis-wiring to Field Power Supplies
    5. 4.5 Heating and Temperature Rise with TPS26610
    6. 4.6 Reduction in PCB Size with TPS26610 for Current Input Protection
  6. 5Conclusion

3.2 Heating and Temperature Rise with Discrete Circuit

As the PTC and Zener diode don’t provide the cut-off protection during miswiring faults, there is a continuous flow of current through the burden resistor, PTC, and Zener diodes. This current flow leads to power dissipation in these components and heating of the entire module. Figure 3-7 provides the temperature rise in PTC during miswiring faults. The temperature of PTC rises ~95°C above ambient temperature during miswiring faults

GUID-20201210-CA0I-DD4W-P3JB-ZCBJ3P70GXK4-low.png Figure 3-7 Temperature rise with Discrete Circuit