| 摘要 |
PURPOSE:To prevent the generation of noises by connecting a resistor for discharging charge charged up to the distribution capacity of a data bus line between the data bus line of which one end is connected to a D-RAM and the ground and discharging the charge on the basis of a time constant determined by the resistor and the capacity. CONSTITUTION:One end of the resistor 41 is connected to a line connecting between each output terminal DOUT of the D-RAM 16 and the input side of a data bus buffer 30 which corresponds to the output terminal DOUT and the other end is earthed. The value of the resistor 41 is selected so that the time constant of a CR circuit constituted by the combination of both the capacity 34, 35 is a proper value. When the value of the resistor 41 is excessively large, discharge is not performed rapidly in a time band turning the line to high impedance, and noises can not be sufficiently suppressed. When the value of the resistor 41 is excessively small, current flows into the ground through the resistor 41 at the transfer of data is increased and the driving efficiency is reduced. In this example, the resistor 41 connected to each line is set up to 5KOMEGA respectively. |
