| 摘要 |
PURPOSE:To form a simple and sure initializing circuit, by providing a power supply rising voltage detecting means which compares a voltage dividing circuit of power supply voltage and a reference voltage lower than the power supply voltage, in an integrated circuit. CONSTITUTION:In an intergrated circuit 21, a lower supply voltage VDD is divided with resistors R1 and R2 and applied to one terminal of a comparator 28. A reference voltage Vref lower than the VDD is generated 26, applied to a + terminal of the comparator 28 and the output detects a power supply rising voltage T. At the application of power supply, the comparator 28 outputs a level L under a prescribed voltage before the power supply voltage rises to the VDD. A clear terminal CL of the integrated circuit 21 is grounded with an external reset switch 23, connected to the power supply VDD via a pull-up resistor R0 mounted internally and an output T of the comparator 28 controls an NAND circuit 24. Thus, a circuit to be initialized 22 is forcedly cleared at the application of power supply, and the clearing can arbitrarily be done with the switch 23 at normal state. |
