SNLA490 March   2025 ISOM8110-Q1 , ISOM8111-Q1 , ISOM8112-Q1 , ISOM8113-Q1 , ISOM8115-Q1 , ISOM8116-Q1 , ISOM8117-Q1 , ISOM8118-Q1

 

  1.   1
  2.   Summary
  3. 1Relay Contact Sticking in OBCs
    1. 1.1 Relays Used in OBCs
    2. 1.2 Causes and Hazards of Relay Contact Sticking
  4. 2About Opto-emulators
    1. 2.1 Introduction to ISOM811x-Q1 and Key Parameters Like CTR
    2. 2.2 Performance Comparison with Optocoupler and Single-Channel Digital Isolator
  5. 3AC Relay Weld Detection in V2L Circuit for OBCs Based on ISOM8118-Q1
    1. 3.1 What Is V2L for OBCs
    2. 3.2 Design Reference for AC Relay Weld Detection Circuit in V2L
    3. 3.3 Design Examples and Selection Guidelines Based on Typical Circuits
      1. 3.3.1 Select Voltage Judgment Threshold VTH and IFmin
      2. 3.3.2 Select Current-limiting Resistor R1
      3. 3.3.3 Select the pull-up resistor R2
  6. 4Summary
  7. 5References

4 Summary

Opto-emulators can save voltage sampling at one end, compared to traditional weld detection solutions that compare the voltages at both ends of a relay with two voltage sampling chips. The ISOM811X-Q1 requires no high-side power supply and allows flexibility in configuration on both the high side and low side, with fewer components required for the peripheral circuit. While meeting the needs of a certain sampling accuracy, it also saves the ADC for the MCU and uses a GPIO port instead, providing advantages in cost control of system design, reduced circuit complexity, and optimized resource utilization. This offers a more cost-effective solution for relay weld detection in V2L for OBC applications.