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protection of output I/O lines with transil?

I have now some new project and there are various I/O going stright out of a complex hybrid chip to external wiring which is a house installation.

The previous circuits had either NOTHING as protection or large PTC resistors in the lines and couple of zener diodes to ground on each lead.

I need to do something of 'present day' kind, but it should still do the job well. I though abt some transil /transorb etc diodes, however it looks like that those suitable for protection of 5V logic lines have leakage of abt 1mA!

And do I have to still add some serial PTC resistors in this case?

How is this handeld to day in general?

Reply to
Otto Sykora
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"Otto Sykora" schreef in bericht news: snipped-for-privacy@4ax.com...

In this case, couldn't You work with optocouplers? That way no dangerous stuff can ever reach Your big chip (apart from really heavy things maybe like lightning, don't know about that). You would have to build an extra psu as well for complete protection off course (afa it can ever be "complete").

Sincerely, Rene

P.S. My suggestion is from a hobbyist's point of view. When I build one thing for my own use, an extra cost is often not of that much importance (hey, it's a hobby :-) and when I make something, I want it to be as good as I can build). Might be that You are working on some commercial thing were money is much more important and an other option would have a better cost-benefit relationship. So it's just "my two cents" ;-).

Reply to
Rene

I would add buffers to the I/O lines. They are cheap to replace - use sockets.

Reply to
Homer J Simpson

I don't know about the latest generation gear from Audio Precision, but on their original gear, that was their solution. The bus drivers were socketed.

Reply to
miso

no way for sockets here, the units are small and all smd stuff on it, no way to place any sockets etc.

I just like to know if someone has somerecent experience with transil etc protection and if still a series ptc resistor is used in such case etc.

Reply to
Otto Sykora

yes I work this way so far, looking for oc going into my cct. BUt those do not solve everything. small oc have also abt 80V C-E, so it must be more protected here. The regulations for building wiring are somehow complex, but it seems that some transil etc have to be placed in front of the oc still. also I wonder, if there is still the need of an series ptc resistor nowadays when the transils are used.

Reply to
Otto Sykora

Find a way. You'll curse the day you didn't.

I would have no faith in a PTC (or an NTC) used for this. A VDR maybe.

Reply to
Homer J Simpson

It would really help to know from what exactly you are trying to protect these drivers. Static or transient? ESD? Speed of signal? Load capacitance?

Reply to
miso

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