| 摘要 |
A circuit for use on an integrated circuit chip for detecting the operative connection of a crystal used to control an on-chip crystal controlled oscillator, which generates a cyclical clock signal, by detecting the presence or absence, respectively, of the cyclical clock signal and for providing an output control signal in response thereto to an on-chip terminal pad control circuit which automatically enables an on-chip terminal pad to be utilized as a clock signal output terminal pad if the cyclical clock signal presence is detected or as a clock signal input terminal pad otherwise. Also, a method of automatically switching the function of a terminal pad on an integrated circuit chip to function as a clock signal output terminal pad or as a clock signal input terminal pad in accordance with detecting the existence or non-existence of a cyclical clock signal generated on-chip.
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