An authorization control circuit (10) comprises a digital signal processor (12) operable to provide digital data output, determine an authorization state, and generate a disable signal. A digital to analog converter (28,60) is coupled to the digital signal processor (12) and is operable to receive the digital data output. The digital to analog converter (28,60) generates analog data in response to the digital data output and is operable to output the analog data and mute the output of analog data. The digital to analog converter (28,60) includes an input (23,25,27,59) operable to receive the disable signal. The digital to analog converter (28,60) mutes the output of analog data in response to the disable signal.