1-wire galvanic isolation

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1 wire optoisolation

At the moment I try to make a galvanic isolated 1-wire slave system because i have problems with ground loops between 1-wire sensors and the master module.
Does anyone have a solution to this?
Google cant really give me any relevant information on galvanic isolation of 1-wire slave systems. Remember it has to be asolated at slave level so i cant split the 1-wire in rxd and txd at the master. I think it should work with optocouplers but maybe the Adum series from analog is a solution. Any ideas or schematics??

greets P.
 

1wire optoisolation

1wire optoisolation is not easy. Grounds loop on 1 wire bus can be made only
if you didn't read carefully what 1wire bus means.

1 wire bus could have 2wires (parasytic supply) or 3 wires (separate supply).
Both buses have one GROUND wire. So how could you have ground loops ?
Imagine a star topolgy or a ring topology. Use for the wire a CAT5 cable and one twisted pair (signal-gnd) for 2wire bus or two twisted pairs (signal-GND, VCC-gnd) for 3 wire bus.


an ideea about 1w optoisolation:
**broken link removed**
 

1-wire isolate

The ground loops are between sensors that are submurged in water, the signals from the ION selective sensors are very weak and easely disturbed. I use the DS2450 A/D converter and by isolating the aplifiers and A/D conversion I can get accurate measuments.
 

isolated 1-wire

C&D technologies makes DC/DC PSU's HB04 series with high isolation. You could drive earth with buffer that has input referenced to your isolated 0V also. Use IL711-x or something simillar to isolate serial signal. If you have 1 wire as default, use small MCU or some hardware solution to inteface over isolation IC. Add ferrites on all your cables. Make sure that you drive shielding for your measurement to protect input connections from leakage currents.
 

galvanic isolated a/d converter


Oh, chemistry...
The high impedance sensors need first current to voltage converters to increase the levels, then the AD issues and the isolation on communication line.
The problem you have is not exactly "ground loop" but ground isolation problem. Without ground isolation the sensor could have leackage currents to the input circuit as long is grounded and not floated.
 

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