| 摘要 |
<p>PURPOSE:To obtain the output circuit which can maintain a stable output terminal state even at the time of a power source start-up. CONSTITUTION:A level detecting circuit 11 which detects a power source potential 10 and an Nch transistor(TR) 12 which inputs the output of the detecting circuit 11 at its gate are interposed between the source terminal of an Nch output buffer 4 and a ground potential and a capacitor 13 is further interposed between the gate of the Nch TR12 and ground potential to control the Nch output buffer, thereby determining the state of an output terminal 5. The Nch TR does not turn ON until the power source potential reaches a specific level after rising, so high impedance is obtained at the output terminal 5 even unless a control signal 3 is changeable. When the power source potential further rises and reaches an internal circuit stable operating voltage, the Nch TR 12 turns ON, but the high impedance is maintained at the output terminal 5 since the control signal 3 has a logical level 'H'.</p> |
