SLLA526C October   2020  – September 2023 ISO6720-Q1 , ISO6721 , ISO6721-Q1 , ISO6731 , ISO6740 , ISO6741 , ISO6741-Q1 , ISO6742 , ISO7021 , ISO7041 , ISO7131CC , ISO7140CC , ISO7140FCC , ISO7141CC , ISO7141FCC , ISO7142CC , ISO7142CC-Q1 , ISO721 , ISO721-Q1 , ISO721M , ISO721M-EP , ISO722 , ISO722-Q1 , ISO7220A , ISO7220A-Q1 , ISO7220B , ISO7220C , ISO7220M , ISO7221A , ISO7221A-Q1 , ISO7221B , ISO7221C , ISO7221C-HT , ISO7221C-Q1 , ISO7221M , ISO722M , ISO7230C , ISO7230M , ISO7231C , ISO7231C-Q1 , ISO7231M , ISO7240C , ISO7240CF , ISO7240CF-Q1 , ISO7240M , ISO7241A-EP , ISO7241C , ISO7241C-Q1 , ISO7241M , ISO7242C , ISO7242C-Q1 , ISO7242M , ISO7310-Q1 , ISO7310C , ISO7310FC , ISO7320-Q1 , ISO7320C , ISO7320FC , ISO7321-Q1 , ISO7321C , ISO7321FC , ISO7330-Q1 , ISO7330C , ISO7330FC , ISO7331-Q1 , ISO7331C , ISO7331FC , ISO7340-Q1 , ISO7340C , ISO7340FC , ISO7341-Q1 , ISO7341C , ISO7341FC , ISO7342-Q1 , ISO7342C , ISO7342FC , ISO7420 , ISO7420E , ISO7420FCC , ISO7420FE , ISO7420M , ISO7421 , ISO7421-EP , ISO7421A-Q1 , ISO7421E , ISO7421E-Q1 , ISO7421FE , ISO7520C , ISO7521C , ISO7631FC , ISO7631FM , ISO7640FM , ISO7641FC , ISO7641FM , ISO7710 , ISO7710-Q1 , ISO7720 , ISO7720-Q1 , ISO7721 , ISO7721-Q1 , ISO7730 , ISO7730-Q1 , ISO7731 , ISO7731-Q1 , ISO7740 , ISO7740-Q1 , ISO7741 , ISO7741-Q1 , ISO7741E-Q1 , ISO7742 , ISO7742-Q1 , ISO7760 , ISO7760-Q1 , ISO7761 , ISO7761-Q1 , ISO7762 , ISO7762-Q1 , ISO7763 , ISO7763-Q1 , ISO7810 , ISO7820 , ISO7821 , ISO7830 , ISO7831 , ISO7840 , ISO7841 , ISO7842 , ISOW7821 , ISOW7840 , ISOW7841 , ISOW7841A-Q1 , ISOW7842 , ISOW7843 , ISOW7844

 

  1.   1
  2.   Abstract
  3. 1Isolator Construction
  4. 2Switching Performance
  5. 3Isolator Lifetime Through TDDB Test
  6. 4Solution Size
  7. 5Aging and Reliability
  8. 6Common-Mode Transient Immunity (CMTI)
  9. 7Optocoupler Current Input vs Digital Isolator CMOS Voltage Input
  10. 8Conclusion
  11. 9References

6 Common-Mode Transient Immunity (CMTI)

There are many applications (like solar inverter) that have very high voltages being switched for either conversion or regulation, leading to high common-mode switching noise, and there are other applications (like motor drives) that have inductive loads causing high ringing noise. These common-mode noises appearing across the isolator can couple into an internal circuit of the device and disrupt normal operation.

One of the ways to prevent such noise from affecting internal circuit is to implement a differential design with good common-mode noise rejection. The single-ended channel design of an optocoupler and absence of a common-mode noise rejection circuit makes the receiver in optocoupler vulnerable to external common-mode noise.

Even with internal Faraday shielding, a typical high-speed optocoupler only supports a minimum CMTI of ±20 kV/µs. In comparison, ISO6741 employs a differential isolation channel design and a receiver with very high common-mode noise rejection, thereby offering a minimum CMTI of ±50 kV/µs.