| 摘要 |
<p>PROBLEM TO BE SOLVED: To allow stable write and erase of built-in flash memory in a comparatively wide voltage region of the external power source covering a low-voltage operation in a microcomputer with built-in flash memory. SOLUTION: A voltage clamp means 44 which uses a reference voltage generating circuit and a constant-voltage circuit forms a voltage Vfix small in power source voltage dependence and further its voltage level is clamped on a voltage lower than the single power source voltage Vcc which is fed externally within a permissible range. Thereby, the step-up voltage, namely write and erase voltage, generated by step-up means (45-48) which are operated by the clamp voltage Vfix does not depend on the external power source voltage Vcc.</p> |
