Integrated Current Sensing Technique Suitable for Step-Down Switch-Mode Power Converters

A new on-chip current sensing circuit suitable for step-down switch-mode power converters (SMPC) is presented in this paper. It can be used in a high speed SMPC. The sense voltage is quite accurate and temperature independent. The structure is very simple. Only eight transistors and a sensing resistor are used. This current sensing technique has been fabricated with a standard 0.5µm DPDM CMOS process. Experimental results show that the proposed circuit can work well in DC-DC converters such that the loading current can be managed through control theories.