| 摘要 |
<p>PURPOSE:To reduce the current consumption of an oscillation circuit even if a microcomputer is normally working with the power voltage of a high level by supplying the internal power voltage of a fixed level lower than the working power voltage of the microcomputer and supplied to a ring oscillator from the outside. CONSTITUTION:When a ring oscillator 1 is oscillating, the output of an inverter IV6 is set at a low level and P-channel transistor TR Q1 conducts. At the same time, an N-channel TR Q5 becomes inconductive and an N-channel non- doped TR Q7 also becomes inconductive. Then the voltage is limited to about 2.7V at a contact N1 by an N-channel TR Q4, a P-channel non-doped TR Q3, and an N-channel non-doped TR Q2. Therefore the internal power voltage Vip is fixed at 7V by a TR Q6 even if the external power voltage Vcc exceeds 2.7V.</p> |
