Research on low dropout operation of current-mode DC-DC buck converters with heavy loads

The linear slope compensation effect on peak current and load capability of DC-DC converter is proven in this paper. In order to solve the problem of low dropout operation with heavy loads, the circuit for counteracting part of the slope current is proposed on the basis of piecewise linear slope compensation. And adjustable slope current and low dropout operation is achieved during clamp state, which extends the battery life and suits for portable applications. The circuit is concise, simple to implement and has been fabricated in a current-mode DC-DC buck converter with 600 mA load current for validation. Experimental results show that the low dropout operation with 600 mA load current and output voltage of 2.5 V and 3.3 V at duty cycle of 100% is realized.