Regulator runs PLL or spread spectrum

High-efficiency 2.25MHz synchronous buck regulator is claimed ideal for single cell Li-ion, or multicell alkaline/NiCad/NiMH applications.

New from Linear Technology, the LTC3543 is a high-efficiency 2.25MHz synchronous buck regulator that can deliver up to 600mA of continuous output current from a 2 x 3mm DFN package.

The LTC3543 can run in either a constant 2.25MHz frequency, spread spectrum or synchronised phase lock loop (PLL) mode, offering multiple choices for very low noise operation.

Its current mode architecture operates from an input voltage range of 2.5 to 5.5V, making it ideal for single cell Li-ion, or multicell alkaline/NiCad/NiMH applications.

It can generate output voltages as low as 0.6V, enabling it to power the latest generation of low voltage DSPs and microcontrollers.

Its 2.25MHz switching frequency enables the use of tiny, low cost ceramic capacitors and inductors less than 1mm in height, providing a very compact solution footprint for handheld applications.

The LTC3543 uses internal switches with an on-resistance of only 0.35ohm (N-channel) and 0.45ohm (P-channel) to deliver efficiencies as high as 95%.

It also uses low dropout 100% duty cycle operation to allow output voltages equal to the input voltage, further extending battery runtime.

For maximum light load efficiency, the LTC3543 uses an automatic low ripple (less than 20mV peak-peak) Burst Mode operation with only 45uA no load quiescent current.

If the application is noise sensitive, the Burst Mode operation can be replaced with a lower noise pulse-skipping, spread spectrum or PLL (to an external clock between 1MHz and 3MHz) mode.

In all modes, the device maintains shutdown currents of less than 1uA, maximising battery runtime.

Other features include +/-2% output voltage accuracy, internal soft-start and overtemperature protection.

The LTC3543EDCB in available in a 2 x 3mm DFN-6 package and is available from stock.

Pricing starts at US $1.95 each for both parts in 1000-piece quantities.

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