Switching circuit

摘要

A low impedance load is switched between a power supply source and ground through a series connected power MOSFET the conduction of which is controlled by a switching circuit. The switching circuit includes a linear loop that regulates the switch voltage to a minimum value to produce current flow through the load and the MOSFET. In addition, the switching circuit includes a current supply placed in parallel to the MOSFET which is set to supply a minimum predetermined current that is representative of the value of current flow through the load under an open load condition. If the load current falls below this set current value an open load status flag is provided by the switching circuit as the loop is no longer in regulation.