Ultra‐low startup voltage low output ripple high‐efficiency hysteretic current mode step‐up DC–DC converter

This study proposes a hysteretic current mode step‐up DC–DC converter with ultra‐low startup voltage, low output ripple and high efficiency, which is suitable to be used as a power supply for an accurately voltage controlled systems, high‐efficiency devices and low‐voltage supply applications. A startup module is used for operating the switches when the input voltage is not high enough to supply the control circuit. The output ripple is restricted by a fixed‐hysteretic current mode controller whether the load is heavy or light. The high efficiency is obtained by applying an auto‐mode changed technology under light load. This makes some sub‐circuits of the chip enter into the power save mode and shuts down the power switching devices. At the same time, a back‐gate diode of the rectifying power metal‐oxide semiconductor device is used for maintaining output voltage. The chip has been made with a standard 0.35‐μm complementary metal‐oxide semiconductor process forming an area of only 960 μm × 820 μm. Experimental results show that the minimum startup voltage is 0.8 V; and the output voltage ripple is <10 mV. Moreover, the peak efficiency is 95% with a heavy load that can prolong battery life.