High Voltage Range Current Limiter

[Joeisi]

Hello,

I am currently designing a electronic design that requires an Optocoupler connected to a 20 Vrms-400 Vrms AC voltage source. It should be designed to accept a large range of voltages. I was currently thinking about how to current limit the current going into the optocouplers LED. The datasheet of the optocoupler I am thinking of using can be found here: https://www.vishay.com/docs/83653/ild620.pdf


How would I go about current limiting the current going into this optocoupler in a manner that is both small in footprint, and also doesn't cost much? I am currently lost on how to go about this at the moment so any ideas would be greatly appreciated. If there is a different style of optocoupler or IC or such I could use I am completely open to it. However, isolation must be present somewhere in the design.

Thanks in advance.

 

[HMS1021]

Take a look at the data sheet for a Linear LT8300. It is not exactly what you need as it will only support an input of 6V to 100V but it represents the type of technology you are looking to help with your search and may also serve as a starting point for a discrete design. It is in a very small 5-Lead TSOT-23 package. At $3.50 USD I would not call it low cost.