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From: owner-pcadusers
To: technet
Cc: pcadusers
Subject: DES:ISOLATION
Date: Thursday, May 30, 1996 9:32AM

I'm not sure if this is the best place to ask electronics engineering
type questions; so if anyone knows of an engineering-related forum,
please let me know...

I am in the process of designing a power board to military specs, and
one of the requirements is "2500V isolation between primary and
secondary". Using the formula that says 0.12 mils/volt, I am looking
at a 300mil clearance wherever appropriate, right?

One of the components in the design is an opto-isolator in a DIP8
package, and the data sheet guarantees 3000V insulation between
primary and secondary. Since it is packaged in a DIP, and I am
required to use 65 mil pads, I am only left with 235 mils between
primary and secondary, which works out to (235/0.12) 1958.3 volts.

Am I misinterpreting the requirements?
<cut>

I would definitely check the charts again. I just completed laying out a 
board that had 3500v isolation. I only needed 200 mils clearance. PCB and 
engineer are doing just fine. Note: the characteristics of the circuit may 
have been different though.

Scott
also at [log in to unmask]