| 摘要 |
PURPOSE:To drive a buzzer without providing any external mounting parts other than CMOS.IC by providing two terminals for output terminals and connecting the buzzer between said two terminals so that the phases between the output terminals are mutually anti-phase at the sounding and in-phase at the dwell of sounding. CONSTITUTION:Outputs f1, f2, f3 and alarm sounding control input CG are inputted from a frequency dividing part 2 to an alarm shaping circuit 61 via level shift 3 and high voltage operation frequency dividing circuit 4 and the signal waveforms phi113, phi114 of the nodal points 113, 114 thereof are mutually anti-phase at the sounding and in-phase at the dwell of sounding. Hence, the signals appear at output terminals 110, 111 through pre-driving inverters 117, 118 and driving inverters 115, 116 after the nodal points 113, 114, thereby driving a buzzer 9. The dutputs of zero are outputted between the output terminals 110, 111 at the dwell of sounding and the outputs twice the supply voltage at the sounding, whereby the buzzer 9 is directly driven. |
