Optocoupler safety

Always assume that app notes are written and proof-written by idiots.

This should not prevent you from contacting the source for 'clarification'.

RL

As TI has been out of the opto business for some decades, any app info has to be taken with a grain of salt.

Have you considered designing a triggering circuit that works better? That's also an 'engineerin' option.

I assume you mean that you're replacing the whole shebang with a relay, not just the optocoupler.

Your concern re explosive damage is probably justified, but its demonstration (given the energy distribution in the series chain of the fault path) would be extremely difficult to enact singly, or to demonstrate repeatedly.

Optocoupler mfrs have, in the past, shown an appreciable ignorance of the limitations of their products in simple functional, never mind safety-critical, applications.

The package DIL package dimensions alone, persistent despite the decades-long existence of VDE0804 (from which most coordinated safety standards derive) is not the only example.

At one point, creepage-correct long-stroke optocouplers were produced in a tubular package, the material of which could burn like a candle, (though a very smokey one).

It took field application incidents to correct this material flaw.

One step forward......

RL

Sheingold in old "lighten emperiests... spelling way wrong.) and some other analog stuff...

George H.

Yup. And Barrie Gilbert, who iirc wrote the occasional app note. The Tek an d HP guys from the golden age wrote a lot of good stuff. ISTR that Ulrich R ohde did too.

Cheers

Phil Hobbs