The MP28200 is a monolithic power-management unit containing 200mA, high-efficiency, step-down, switching converters. The nanoamp quiescent current provides extremely high efficiency when the load current is down in the ? range. With minimum input voltage as low as 2V, the MP28200 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. 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 MP28200 requires a minimal number of readily available, standard, external components and is available in a small QFN-12 (2mmx2mm) package.