Linear Technology announces the LTC3549, a 2.25MHz, synchronous buck regulator that can deliver up to 250mA of continuous output current from input voltages as low as 1.6V. Using a constant frequency and current mode architecture, the device operates from an input voltage range of 1.6V to 5.5V, making it ideal for single cell Li-Ion, or dual-cell alkaline/NiCad/NiMH applications. It can generate output voltages as low as 0.61V, enabling it to power the latest generation of low-voltage DSPs and microcontrollers. Its 2.25MHz switching frequency enables the utilization of tiny, low cost ceramic capacitors and inductors less than 1mm in height, providing a compact solution footprint for handheld applications.

The LTC3549 uses internal switches with an RDS(ON) of only 0.4 Ohm (N-Channel) and 0.56 Ohm (P-Channel) to deliver efficiencies as high as 93%. It also utilizes low dropout 100% duty cycle operation to allow output voltages equal to VIN, further extending battery run-time. The chip utilizes low ripple Burst Mode operation to provide only 50uA no load quiescent current with less than 20mVPK-PK of output ripple. If the application is noise sensitive, the device can be set in an even lower noise pulse-skipping mode, yet still offers only 300uA of quiescent current. Both parts maintain shutdown current of less than 1uA, further maximizing battery life.

The converter is stable with ceramic capacitors, achieving very low output voltage ripple. Other features include current mode operation for excellent line and load transient response, internal soft-start and over-temperature protection.The LTC3549EDCB is available from stock in 6-lead 2mm x 3mm DFN Packages. Pricing starts at $1.35 each 1,000-piece quantities.