At 09:25 AM 10/9/2009, Harold Hallikainen wrote: >Slight topic drift here... The need for the cheap isolated DC to DC >converter is typically to drive transmit/receive circuitry on an isolated >power supply to avoid ground loops. > >I've got a situation where I need to sense maybe 24 contact closures to >"ground" and drive about 24 open drain outputs. The sense and drive >circuitry needs to be on an isolated supply to avoid a ground loop with >the equipment that is driving it (referenced to its ground). It seems like >the simplest way to get data back and forth is to use a UART in a PIC on >the floating side and two opto-couplers, one in each direction to talk to >a UART on the nonfloating side. That's certainly what I'm doing. The only thing to watch out for is how much supply current the receiving opto on the isolated side needs - some of the faster optos need 50mA to operate the receiver side. I'm very fond of HP's / Agilent's HCPL 25xx / 26xx / 27xx family - I usually start there when looking for an opto for any particular application. Then I'll go looking for less expensive alternatives if needed. I guess it all depends on how fast the data transfers need to occur. How much latency can your application tolerate? dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist