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Topic: Suggestions for RS-422/RS-485 interface chips (Read 996 times) previous topic - next topic

Daniel2

Hi

I'm looking for suggestions for a cost-effective, fault-protected alternative to the standard SN75176 RS422/rs485 driver. 

There are about a thousand different 8-pin driver chips out there for this protocol. What is the most commonly used device when doing RS422/RS485 with fault protection? I'm guessing this will lead me to the cheapest one too.

Originally I designed the PCB for my project to accommodate the SN75176, but now I realize it has no fault protection.  I've ordered a few LT1785 transceivers to try out: they have 60V fault isolation.

My application has 24V, 10A and RS-485 (for DMX) running along one 4-conductor cable. It works perfectly, but I am worried about the day that a cable shorts out-- and the whole network goes POOF!

Daniel

Peter_n

The cheapest RS-485 modules on Ebay are 1 dollar and use the MAX485.
The MAX485 datasheet shows good numbers but also mentioned MAX3080...MAX3089 for fail-save and MAX3430 for fault-tolerant applications.

Daniel2

Thanks Peter.

Yes the MAX485 is equivalent to the SN75176, but have no fault tolerance. MAX3430 is but runs about $5 to $6 in small quantities.

If anyone designs for fault tolerant RS-422, I'd be glad to hear what chips you are using!

graynomad

Have a look at the Intersil range (ISL32600E, ISL3170E, etc), some of them have pretty good specs.

I'm looking into designing a robust 485 system at present, these are likely contenders at this point.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

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