Patent ID: 7242560
Filing Date: 2007-07-10
Classification: H03K

Abstract:
1. An electronic circuit for protecting a field effect transistor from high voltage, comprising: a load impedance connecting the drain of the field effect transistor to a DC power source; a switching device having: a charging device having a terminal receiving continuous direct charging current from the DC power source through a path not including the field effect transistor, the terminal being connected to said switching device to control the state thereof, the terminal also being connected through a diode to a drain of the field effect transistor for discharging current flow from the charging device through the field effect transistor when the field effect transistor is turned ON whereby the switching device is placed in the first state, the diode being reverse biased when the drain of the field effect transistor is short circuited to the DC electric power source whereby the discharging current flow from the charging device through the field effect transistor is blocked to permit the charging current to charge the charging device and thereby place the switching device in the second state and to latch it in the second state as the field effect transistor is turned OFF.