| 摘要 |
<p>PURPOSE:To set up PROM data writing power voltage to plural values by providing the titled circuit with an operation power supply, a writing power supply, a data writing circuit, a protective resistor connected to the writing power supply, a voltage setting circuit to output a voltage selecting signal, and a voltage regulating circuit and using the writing power supply in common. CONSTITUTION:Operation power voltage is outputted by the operation power supply 4 and writing power voltage is outputted by the writing power supply 3. The protective resistor R1 is provided in parallel with a writing circuit 1 and a voltage regulating resistor R2 is connected through a switching MOST Q6 in parallel with the R1. The voltage setting circuit 5 includes FMOS Q3 and a setting signal S3 and a reading signal S4 are usually set up to L and H respectively by a detection circuit 6. When a signal >=10V is inputted to the PROM as an address signal A0, S3 and S4 are turned to H and L respectively. A voltage rising circuit 2 is actuated when a voltage selecting signal S2 is H. By applying specific inputs to the PROM, the data writing power voltage can be set up to plural values.</p> |
