The LTC3406A is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. Supply current during operation is only 20A, dropping to 1A in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3406A ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery runtime portable systems. Automatic Burst Mode operation increases efficiency at light loads, further extending battery runtime.