| 摘要 |
PURPOSE:To put an output MOSFET in a turn off state for an open drain output when the source voltage of a driving cricuit is lower than a lower-limit voltage of operation by providing a specific impedance means between the gate and source of the output MOSFET. CONSTITUTION:The output MOSFETQ3 for the open drain output is driven by CMOSFET inverter circuits Q1 and Q2. In this case, the impedance means which fixes the gate of the output MOSFETQ3 at a low level when the source voltage VDD of driving circuits Q1 and Q2 such as a resistance R or a constant current source Q4 drops below the lower-limit voltage VL of operation is provided between the gate and source of the output MOSFETQ3. Then, even when the driving circuit Q1 and Q2 malfunction at a low voltage, no undesirable output is generated. |
