I am designing a product that should meet ATEX requirements (Intrinsically safe design). Part of the design is a voltage limiter (overvoltage limit of buck-boost converter). Typically Zener diode is the only component acceptable by ATEX standard as a safety voltage limiter (no other circuit composed of more components would be accepted). I am selecting the Zener diode which should meet the following requirements:
- min. total power dissipation 1.5W
- Nominal zener voltage below 4.3V
- Reverse current at 3V below 100uA (or close to this number)
I can not find a suitable component. Searching is difficult as the reverse current is often specified very generally (eg. 5uA @ 1V). My current choice was 1SMB5916BT3G but measurement shows that the leakage current is around 2mA at 3V. Would anybody be able to advise? Maybe try to search for some TVS diodes? Not sure if this would be accepted by the certification authority.