| 摘要 |
PURPOSE:To reduce the power consumption of the crystal oscillating circuit, by connecting the CMOS inverter to which the driving voltage of 0.75V or less is applied in parallel to the crystal oscillator. CONSTITUTION:The voltage of 3V of lithium battery 1 is dropped down to 1.5V and 0.75V each through voltage reducing circuit 2. And the output voltage of 0.75V is applied to oscillating circuit 3 and the 1st frequency dividing circuit 4 in the form of the driving voltage. Oscillating circuit 3 is formed with CMOS inverter 3a and feedback resistance 3b, and variable capacitor 10 plus temperature compensating capacitor 11 are connected to the joint between inverter 3a and resistance 3b. Then quartz oscillator 12 which has oscillation in the band of 3MHz is connected in parallel to resistance 3b. The output of oscillator 12 is divided into the 1-second cycles via the 1st dividing circuit 4, level shifting circuit 5 and the 2nd dividing circuit 6. Then the time is obtained through time counting circuit 7 to be displayed at liquid crystal display part 8. |
