An on-chip latch-up protection circuit. The lath-up protection circuit includes a core circuit, a power switch, and a current extractor. The power switch controls major current flowing through the core circuit. The current extractor detects amplitude of the major current. The power switch, the core circuit and the current extractor are coupled in series between a relatively-high power line and a relatively-low power line. When the major current surpasses a predetermined amplitude, the power switch is turned off, causing latch-up stops.