Some of the key features of the LTC3355 include the following: a V_IN voltage range of 3V to 20V, V_OUT voltage range of 2.7V to 5V, a 1A current mode buck main regulator, and a 5A boost backup regulator powered from a single SuperCapacitor. The boost regulator operates down to 0.5V for maximum utilization of SuperCapacitor energy. It offers programmable SuperCapacitor charge current to 1A with overvoltage protection. The charger supports single cell CC/CV battery charging with programmable V_IN current limit, V_IN power fail indicator, V_CAP power good indicator, and V_OUT power on reset output. The LTC3355 is available in a compact 20-Lead 4mm × 4mm QFN package.