Abstract: A compact low-power on-chip power on reset circuit with a brown-out detection capability was presented for very large scale SoC systems.The proposed POR circuit was designed in Charted 0.35 μm CMOS process with power supply of 3.3 V,the steday current is only 10 μA and the occupied area was 130 μm×110 μm.A long reset delay of more than 100 ms was achieved by only using a picofarad-order on-chip capacitor. Moreover, reset delay was independent of temperature due to the use of temperature-compensated current reference. When temperature changed from －40 ℃ to 90 ℃, reset delay varied from 108.32 ms to 98.95 ms, which means that the variation caused by temperature was less than 10%.