Hi, Please disregard my previous mail. I have two power domains. vmain and vstandby. A signal sig1 is output of a combinational logic in vmain domain. It is registered in vstandby domain. vmain domain can be inactive when vstandby is active What are the potential problems that can occur on such a signal? Should any care be taken when designing this logic. How are signals crossing power domains generally handled. Regards Godwin __________________________________ Do you Yahoo!? Yahoo! Personals - Better first dates. More second dates. http://personals.yahoo.com