Importance

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Abstract

A method and apparatus are provided for suspending or freezing outputs from an isolation barrier system, which may be a digital capacitive isolation barrier system, during the occurrence of events that may disrupt proper operation of the system. Examples of such disruptive events are data rate changes during modem baud rate negotiations, transition to low-power mode, and going off-hook in a telephony system. In each of these cases, the master circuit anticipates the disruption and sends a freeze signal to the isolated circuit. The freeze signal instructs the isolated circuit to enter freeze mode, and no data is sent through the isolation system. Internal control signals are generated and used to establish synchronization and framing after the disruption, and to restore normal operation of the isolation system. In preferred embodiments, the duration of the freeze period may be determined by a timer or by circuitry that detects framing lock or the presence of transients in the system. This invention prevents the transmission of erroneous control signals or corrupted data through the isolation system when it experiences a disruptive event.

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First Claim