A method and apparatus for isolating a noise intolerant device, e.g., a
phase-lock loop of a tuner within a television receiver, from source of
noise. In one embodiment, the apparatus isolates a phase-lock loop
integrated circuit (IC) from the bus, by providing an isolation buffer
that allows the receiver to only pass data to the tuner's phase-lock loop
IC when a tune command is issued by a processor. When not being tuned,
the IIC lines to the tuner are held HIGH by a buffer until needed again
to perform the tuning function. This allows the demodulation circuitry to
use a setting for a carrier tracking-loop that optimizes bit error rate
performance.