SYNCHRONIZATION CIRCUIT FOR ELECTRONIC DEVICE AND METHOD FOR GENERATING AND SUPPLYING SYNCHRONIZATION SIGNAL

摘要

PROBLEM TO BE SOLVED: To evade reflection between signals and to eliminate changes in synchronization pulses by comparing an external synchronization signal and an internal synchronization signal and supplying one of the synchronization signals depending on whether a synchronization circuit is a master mode or a slave mode. SOLUTION: When the synchronization signal SINC is connected to the input/output terminal of this synchronization circuit 1, an oscillator 2 outputs sawtooth-shaped wave signals 3. Then, a clip circuit 4 clips the sawtooth-shaped wave signals 3, generates the internal synchronization signal 5 and supplies it to a comparator 6. The comparator 6 inputs the external synchronization signal SINC, compares it with the internal synchronization signal 5 and recognizes whether or not the external synchronization signal SINC arrives. In the case that it does not arrive, control is performed so as to close a normally opened switch 7. As a result, the internal synchronization signal generated in the clip circuit 4 is connected to a circuit node U and outputted to a circuit constitution part 8. Also, in the case that the external synchronization signal SINC arrives, it is directly outputted to the circuit constitution part 8.