A voltage is applied across a control resistor, and the voltage is caused to decay. The decay is monitored by a testing circuit such as a comparator. When the voltage across the control resistor has decayed to a value less than or equal to a reference voltage in the comparator, a switch time period is...http://www.google.com.au/patents/US6762608?utm_source=gb-gplus-sharePatent US6762608 - Apparatus and method for testing fuses
