There are many specifications that cover required connection
/ isolation between circuit ground and chassis / safety
ground. Typically things like withstanding voltage,
resistance, capacitance, etc are specified. Depending on the
your design target usage, you may need to comply with
relevant specification to be certified. If this isn't issue
for your use case, you may consider "adopting" one of these
existing standards. Otherwise, implementing a provision for
connection component(s) such as short, resistor, resistor +
capacitor, between circuit ground and chassis / safety
ground is a good idea, whether or not you end up installing
them. A high value resistor, e.g. megaohm or so, may be a
good idea to avoid potential static charge buildup between
circuit and chassis.
Regards,
Ivor
On 5/9/2018 9:16 AM, Guru Shankara wrote:
Hi Experts,
I am working on a modem design that is powered by an AC/DC supply (isolated).
The design includes a base board that hosts a mezzanine/daughter card and
both the baseboard and the mezzanine cards are powered by 12V DC.
The chassis walls and misc. mechanical hardware have a conductive coating on
the inside and will be connected to the chassis/safety/earth ground of the
AC/DC power supply.
As the name implies, the chassis/safety/earth ground provides for safety of
the operator if there is a situation where the higher voltage side line of
the AC/DC supply rips off and makes contact with the chassis.
So, I prefer NOT to connect the board logic ground to the
chassis/safety/earth ground of the supply.
Any thoughts on if I should connect them together or not?
Also, if they need to be connected, is there a recommended method?
Really appreciate your help.
Thank you,
Gurushankar
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