DC CONTROL CIRCUIT

摘要

PCT No. PCT/EP95/01371 Sec. 371 Date Jul. 23, 1996 Sec. 102(e) Date Jul. 23, 1996 PCT Filed Apr. 12, 1995 PCT Pub. No. WO95/28767 PCT Pub. Date Oct. 26, 1995A control circuit for turning off or on direct current flowing through an inductive load (12) to ground uses a semiconductor switch (11), for example a MOSFET, having a first input terminal (D), a control terminal (G), and a second output terminal (S) to the load. A semiconductor freewheel diode (16) is coupled between the switch second terminal and ground, in parallel with the load. The freewheel diode has a current-conducting state and a current non-conducting state. A switching-off current source (19) is coupled between the second terminal and the control terminal; it reduces the magnitude of the switching control current (+/-IGS) flowing into the control terminal of the MOSFET, as a function of voltage at the second terminal of the switch and the input to the freewheel diode. A minimum value (+/-IIGSmin) of the switching control current is reached when the voltage at the second terminal of the switch reaches ground potential. The current-increase or current-decrease time intervals are influenced by the current sources 18 and 19 in response to the freewheel voltage causing rapid switching without spikes and power loss.