| 摘要 |
<p>PURPOSE: To obtain a triangular wave oscillation circuit capable of being synchronized with an external clock signal and oscillating the triangular wave with a stable amplitude by providing 1st, 2nd comparators and a flip-flop and controlling the charge/ discharge of a capacitor from a current source in response to an output of the flip-flop. CONSTITUTION: This circuit includes a charge discharge circuit 81 selecting charging or discharging so as to provide an output of a triangular wave voltage, a reference voltage switching circuit 82 selecting either of two reference voltages, 1st and 2nd comparators 83, 84, and a flip-flop 85 controlling the charge discharge circuit 81 in response to an output of the comparators 83, 84. Through the constitution above, a switching transistor(TR) 104 controlling the reference voltage switching circuit 82 is conductive for a period when a reference clock is at an H level to decrease a voltage at a connecting point B. Conversely the switching transistor(TR) 104 controlling the reference voltage switching circuit 82 is nonconductive for a period when a reference clock is at an L level to increase the voltage at the connecting point B. Thus, the amplitude of the outputted triangular wave is kept within a range between constant upper and lower levels.</p> |
