ENHANCED OVERCURRENT PROTECTION SYSTEM
Publication Date: 2002-Nov-26
The IP.com Prior Art Database
Existing “soft hiccup” overcurrent protection circuits do not allow a power controller to recover from an overcurrent condition (even if the overcurrent condition has been cleared), unless the system is restarted by completely discharging the soft start capacitor. As an overcurrent event is detected, output gate blanking is removed (to minimize gate on time in overcurrent) and from that point, the system is subject to tripping off when it detects the current spike at the leading edge of the gate pulse that results. Furthermore, most “soft hiccup” overcurrent protection circuits are unable to recover from an overcurrent condition when the output driver blanking is disabled because it can not discern between an actual over current condition and a normal leading edge switching spike. If blanking is not disabled, then if an overcurrent condition persists, the device is subjected to more and possibly damaging power dissipation. However, rapid response to overcurrent conditions is a highly desirable market feature and basic customer requirement for power controllers. Thus, there is a need for a means to quickly allow a power controller to recover from an overcurrent event. The concept proposed is to disable blanking to reduce FET power dissipation, but re-assert it every n cycles to restore precision of detection. It represents a compromise between recovery response time and FET power limiting during load fault conditions.