FASTTILLSTANDSOMKOPPLARE

摘要

A high voltage capacitive drive circuit for coupling a dc or pulsed dc input voltage from a control input to a relay having a high voltage output circuit is described in which the output of the high voltage relay circuit is electrically isolated from the control input thereto without the use of optical couplers. The combined capacitive drive circuit and high voltage switch circuit of the present invention may be integrated on a single silicon chip using conventional isolation fabrication techniques to provide good isolation between the control input and the output of the high voltage relay circuit. A pair of matched capacitive couplers are driven in a push-pull mode to pump electrical charge to a floating control circuit which turns on the high voltage relay contact. An exclusive OR circuit prevents high voltage signals on the contact terminals from inadvertently turning the contact ON or OFF by being responsive only to out of phase inputs. The described high voltage switch and capacitively coupled drive circuit is suitable for fabrication on a single semiconductor chip.