| 摘要 |
PURPOSE:To uniform the sound voltage of information sound obtained by dividing oscillation frequency, to improve the accuracy of a timer consisting of an oscillation circuit, a frequency divider and a sound generating means and to reduce the cost of the timer by combining a built-in resistor with a built-in capacitor to form the oscillation circuit, integrating the oscillation circuit in a timer IC and adjusting oscillation frequency. CONSTITUTION:Relation among oscillation frequency fosc, a resistor value R and a capacitor C in a CR oscillation circuit 13 is fosc = 1/(KCR), and provided that K is a constant. Although the frequency is changed even if either one of the C and R is changed, the frequency is adjusted by changing the resistor value R e.g. advantageous for areas. The value of the capacitor C is fixed by a built-in value. The oscillation frequency is adjusted by applying voltage to an IC in an IC tester inspecting process at the time of shipping the IC, oscillating the IC and counting the oscillation frequency by reverse operation from an output waveform obtained from a terminal for connecting a buzzer 11. Since all oscillation circuit elements are built in the IC and the IC is provided with an adjusting means for an element changing the oscillation frequency, the timer having required accuracy can be inexpensively provided to a market. |
