SLVS485 is a nonsynchronous step-down controller that is ideally suited for systems powered from a 5-V or 3.3-V bus or for applications powered from a 1-cell Li-Ion battery or from a 2- to 4-cell NiCd, NiMH, or alkaline battery. This controller uses a minimum on time, minimum off time control scheme and consumes only 20-µA quiescent current to achieve highest efficiency over a wide load current range. The TPS6420x is suitable for applications such as USB powered peripherals, organizers, PDAs, handheld PCs, low power DSP supply, digital cameras, hard disk drives, and portable audio players.