Buck the output trend

Linear Technology Corporation

has released the LTC3448, a 2.25 MHz (or 1.5MHz) synchronous buck regulator which can deliver up to 600mA of continuous output current.

It operates in two modes; first, when output current is greater than 3mA, it switches at a constant frequency of 2.25MHz. If output current drops to 3mA or below, it automatically transitions into a very low noise LDO mode consuming 32uA of quiescent current.

Linear says that output ripple is less than 5mV(P-P) in switching mode and is low noise in LDO mode, making it ideal for low noise applications such as handheld wireless applications.

Using a current mode architecture, the LTC3448 operates from an input voltage range of 2.5V to 5.5V, making it ideal for single cell Li-Ion, multi-cell Alkaline or NiMH applications. It can reportedly generate output voltages as low as 0.6V, enabling it to power the latest generation of low voltage DSPs and microcontrollers.

The user can set the LTC3448's switching frequency to either 1.5 MHz or 2.25MHz and can synchronise the device up to 4MHz allowing the utilisation of ceramic capacitors and inductors less than 1.2 mm in height. Alternately, the part can be synchronised to an external clock.

The LTC3448 uses internal synchronous switches with an R(DS(ON)) of 0.35 Ohm and 0.40 Ohm to deliver efficiencies as high as 96%. It also utilises low dropout 100% duty cycle operation to allow output voltages approaching V(IN), further extending battery run-time. Light load quiescent current is 32uA and <1uA in shutdown.

The LTC3448's LDO mode can be enabled automatically or via an external input. Linear says that the LTC3448 is ideal for handheld applications requiring both low noise operation and low quiescent currents.

The LTC3448EDD is available in a 3mm x 3mm DFN-8 package while the LTC3448EMS8E is available in a thermally enhanced MSOP-8 package.

Both are available from stock. Pricing starts at $2.05 each for both package options in 1,000-piece quantities.