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

4.2 Accurate Current Limiting with TPS26610

TPS26610 has an accurate limiting for protection with 249Ω burden resistor from mis-wiring faults to field supplies with voltage up-to Vs supply of the device.

Figure 4-2 provides the variation of current limit of TPS26610 with temperature.

GUID-20201210-CA0I-SBVX-3QT6-CV5JHSSQS26J-low.svg Figure 4-2 Current Limit with TPS26610

With accurate current limiting, the power dissipation in burden is reduced and numbers of burden resistors are reduced. Table 4-1 summarizes the number of 0805 (125 mW) burden resistors for different values of RBurden.

Table 4-1 Reduced Power Dissipation in Burden Resistor with TPS26610
ILIM(max) RBurden (Ω) Power Dissipated in RBurden (mW) Number of 0805 (125mW) burden resistors required in Parallel
35 mA 249 305 3
35 mA 100 122.5 1
35 mA 49 61.25 1