| 摘要 |
<p>PURPOSE:To enable to write in the cell of ROM surely, by controlling the control current supply circuit controlling ON-OFF of the write-in current switching circuit via the ON voltage control circuit detecting the voltage more than specified value. CONSTITUTION:When the address voltage fed to the constant current control current supply circuit 20 is more than the set voltage of the ON voltage control circuit 30 providing the resistor R1 and Zener diode D2, the transistor T3 of the circuit 20 is conductive, and the constant current from the circuit 20 is given to the output terminal of the decoder formed with PNP transistor group Td1... and the transistor T1 of the write-in current switch control circuit 10 to turn on the circuit 10. The write-in current is fed to the transistor Qc forming PROM cell without loss independently of the change in the set voltage due to the dispersion of components for the circuit 30, ensuring the write-in of information due to junction short circuit.</p> |
