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Do I need to add capacitor to parts isolated by octocoupler?

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isolated gnd?

Hi

If I have a circuit the have two parts and they are isolated by optocoupler.(both power and data isolated).Is it necessary to add a 1nf 1000V capacitor between two ground? is there any need to add protection device?

Regards :D
 

Re: isolated gnd?

If the only connection is optical you should consider them totally independent circuits and do things to them separately. The closest they should be connected is in the case of a common power supply where they both have wires running back to the supply terminals.

The two circuits should be safety grounded separately.
 

Re: isolated gnd?

hi

How do this? "The two circuits should be safety grounded separately"

Assume that the two circuit get power from isolated dc/dc converters that both dc/dc converters have 24vdc inputs.
 

Re: isolated gnd?

I was making some assumption about your circuits. In general they have to comply with the safety laws. If this product is battery powered there is no safety ground requirement. If it is AC mains powered there is the requirement. If they are in the same box just one safety ground connection is required.
 

Re: isolated gnd?

Hello

I don't understand the sentence

"If this product is battery powered there is no safety ground requirement",

is that means for a battery powered products, grounds don't need to be isolated?
 

Re: isolated gnd?

It means that the safety laws do not require the outside case of battery powered equipment be connected to earth.
 

Re: isolated gnd?

Hi,

1) What is meant is circuit before and after optocoupler should be considered as separate circuits. And each behaves independent of the other. No ground should be made common between them.

2) Battery: There is no earth connexion.

BRM
 

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