The MP28300 is a monolithic power-management unit containing 300mA, high-efficiency, step-down, switching converters and a 100mA LDO regulator. The nanoamp quiescent current provides extremely high efficiency when the load current is down in the µA range. With minimum input voltage as low as 2V, the MP28300 allows the system to operate directly from the battery. The constant-on-time control scheme provides fast transient response, high light-load efficiency, and requires minimal capacitance. The regulation can be made tight by integrating an error amplifier to correct the output voltage. An 100mA LDO regulator provides easy system configuration with clean output voltage. The CTRL pins control the on/off and output voltage selection functions. Fault protection features include under-voltage lockout (UVLO), over-current protection (OCP), and thermal shutdown. The MP28300 requires a minimal number of readily available, standard, external components and is available in a small QFN-12 (2mmx2mm) package.