A High Reliable Over-Current Protection Circuit with Low Power Consumption

This paper shows a kind of over-current protection circuits used to power management with the function of pre-comparison, low power consumption and rapid response ability. Power consumption is mainly by the pre-comparison circuits detecting current in real time with low power consumption. The later stage circuits begin to work once load current exceeds the threshold voltage of pre-comparison. The middle comparator with positive feedback can compel sampling voltage to follow output voltage. During current fault, the power MOSFET is automatically turned off (5 us) if the charge current exceeds the threshold voltage of over-current protection circuits. This can prevent the damage from the frequent switch. The circuits are designed in OKI 0.5 um. The simulation results of HSPICE show the over-current circuits are low power consumption and high reliability. Circuit in this paper is highly practical in USB protection chip.