| 摘要 |
PURPOSE:To decrease the chip area by using a voltage drop across a resistor by an electromotive force of a photovoltaic diode array so as to switch a normally-ON type drive transistor (TR) into the OFF-state. CONSTITUTION:The titled circuit consists of a light emitting element 1 generating an optical signal in response to an input signal, the photovoltaic diode array 2 generating an electromotive force by the optical signal, and a power MOSFET 3 receiving the electromotive force between the gate and the substrate thereby changing its state from the 1st impedance state into the 2nd impedance state to constitute a closed circuit in which the electromotive force caused between positive and negative electrodes of the array 2 is fed between the gate and the base of the FET 3 via a resistor 4. Further, the normally-ON type drive TR 5 is provided, in which the drain and source are connected to the gate and the base of the FET 3 and which is biased by a voltage drop caused across the resistor 4. Thus, the rapid charging circuit for the FET 3 is driven by the array 2 only and the chip area is decreased. |
