LOGIC THRESHOLD VARIABLE INPUT CIRCUIT AND CURRENT DRIVE CAPABILITY VARIABLE OUTPUT CIRCUIT

摘要

PURPOSE:To obtain an input circuit whose logic threshold level is variable and an output circuit whose output current is variable by activating selectively a 2nd P-channel MOS transistor(TR) and a 2nd N-channel MOS TR connected in parallel through the use of a switching means. CONSTITUTION:A P-channel MOS transistor(TR) 3 and an N-channel MOS TR 6 are turned on or off by an input signal from a controller 9. That is, when the input signal from the controller 9 is zero, the TR 3 is turned on and an inverter of the input circuit consists of P-channel MOS TRs 1, 3, 4 and an N-channel MOS TR2. Furthermore, when the input signal from the controller 9 is logical 1, the TR 6 is turned on and the inverter is consists of the TRs 1, 2, 5, 6. Since the ratio of the size of the P-channel MOS TR and the N- channel MOS TR forming the inverter changes depending whether the level of the input signal from the controller 9 is 0 or 1, the logic threshold for the input circuit is changed.