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

2.2 Performance Comparison with Optocoupler and Single-Channel Digital Isolator

Compared to single-channel digital isolators, the ISOM811x-Q1 opto-emulators require no input and output power supply and have no reference ground limitations, thus allowing flexibility in configuration in both high-side and low-side applications, greatly simplifying the design of high-voltage side power supply circuits. In addition, high-frequency common-mode interference in strong electrical systems is mostly coupled through parasitic capacitance, while the opto-emulators’ feature of current-driven input facilitates signal immunity.

Compared to optocouplers, the ISOM811x-Q1 opto-emulators offer significant reliability and performance advantages, including high bandwidth, low switching delay, wider temperature ranges, flat CTR, and tight process control, resulting in minimal variations. In addition, the LED input stage of the opto-emulator consumes less power in applications than optocouplers, since there is no aging effect and temperature variation to compensate for. A comparison is shown in the table below:

Parameter ISOM811X Optocoupler A Optocoupler B
Isolation technology SiO2 Optical Optical
Input type Uni & bidirectional Unidirectional Unidirectional
VF (Typ) (V) 1.2 1.2 1.25
Switching time (μs) 5/3 3/3 3/3
CTR range @ IF = 5mA 100% to 560% 50% to 600% 50% to 600%
Bandwidth (Typ) (KHz) 680 30 NA
Temperature range (°C) -55 to +125 -55 to +110 -55 to +100
Pin pitch (mm) 2.54 (DFG) & 1.27 (DFH) 1.27 2.54