a semiconductor integrated circuit device uses two keeper cells per configuration and / or enable bit as dual redundant storage with error detection thereof . one of the two keeper cells stores a logic level and the other keeper cell stores the inverse of that logic level before the integrated circuit device goes into a low power mode . an exclusive or is performed on the outputs of the two keeper cells such that if the two keeper cells of the keeper cell pair do not have opposite logic levels stored therein , then the respective xor outputs an error signal for that keeper cell pair and the error signal is used to force the integrated circuit device out of the low power mode , depending on software control , with or without disturbing input - output configuration control and data states present at the time the low power mode was entered .