Torex Semiconductor’s XC9141/XC9142 series of 0.8A step-up DC/DC converters come with an input–output disconnection function (load disconnection function) to prevent malfunctioning during standby, and for device functionality that enables power supply to RTC.
When the output voltage is 3.3V, the IC can start from an input voltage of 0.9V with a resistance load of 100Ω, enabling use in devices driven by one alkaline or nickel-hydrogen battery. The input voltage range is 0.65V to 6.0V, and the output voltage range can be set from 1.8V to 5.5V (accuracy ±2.0%) in steps of 0.1V. A switching frequency of 1.2MHz or 3.0MHz can be selected to match the application.
0.8A step-up DC/DC converters in a tiny package – [Link]