On-chip single-inductor dual-output DC-DC boost converter having dual output/input modes for utilizing external power transistor drive and micro-computer controlled MPPT

A compact on-chip SIDO DC-DC converter is proposed for portable equipments operating with a battery or a solar cell. A current up to 30mA is supplied with own transistors in an internal drive mode and more than 100mA by utilizing external power transistors in an external drive mode. The efficiencies are 85% and 84% for each case. A cross regulation problem is solved by inserting an extra cycle before switching the outputs. For solar cell operation, two features are implemented. Any kind of maximum power point tracking MPPT is available by receiving a clock signal calculated by a micro-computer. The converter exploits 99% of the expected maximum power of a solar cell. Backward current protection reduces a leak current by three orders without any performance losses when the light is not available like as in the night.