JP2731655B

PURPOSE:To apply a photovoltaic force of a photovoltaic force diode array effectively between a gate and a source of an output MOSFET by supplying a weak current only to a 1st resistor and a 1st control TR in the steady-state. CONSTITUTION:When an input current flows to a light emitting diode 1, an optical signal is generated from the light emitting diode 1. A photovoltaic force diode array 2 generates an optical current upon the receipt of the optical signal. The current flows through a resistor 5 via a source and a drain of a control TR 4 in the low impedance state. When a voltage generated across the resistor 5 is applied between a gate and a source of the control TR 4, the control TR 4 reaches a high impedance state. Thus, a current from the photovoltaic force diode array 2 charges the gate and the source of the output MOSFET 3.