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Linear Tech unveils compact solution for dual output voltage rails

Posted: 28 Apr 2005 ?? ?Print Version ?Bookmark and Share

Keywords:buck regulator? regulator? linear technology? ltc3548?

A dual output, high efficiency, 2.25MHz, synchronous buck regulator that can deliver up to 800mA of continuous output current from one channel and up to 400mA from the other was recently rolled out by Linear Technology Corp.

Using a constant frequency and current mode architecture, the LTC3548 operates from an input voltage range of 2.5V to 5.5V, making it a suitable solution for single cell Li-ion, multi-cell alkaline or NiMH applications. It can generate two independent output voltages as low as 0.6V, enabling it to power the latest generation of low voltage DSPs and microcontrollers. In addition, its 2.25MHz switching frequency of allows the use of tiny, low cost ceramic capacitors and inductors less than 1mm in height.

The new regulator uses internal switches with an RDS(ON) of 0.35 ohm to deliver efficiencies as high as 95 percent. It utilizes low dropout 100 percent duty cycle operation to allow output voltages up to VIN, further extending battery run-time. No load quiescent current is 40?A (both channels), and <1?A in shutdown ensuring optimum battery life. The LTC3548 utilizes automatic Burst Mode operation, reducing gate charge losses when the load current drops below the level required for continuous operation and providing optimum efficiency at light loads. If the application is noise sensitive, the user can disable Burst Mode, replacing it with a lower noise pulse-skipping mode. Additional features include short-circuit protection, power-on reset output, and optional external synchronization capability.

Furthermore, the LTC3548 is stable with ceramic capacitors, achieving low output voltage ripple. This new product is suitable for handheld applications requiring dual outputs up to 400mA and 800mA, high efficiency, and very small solution footprint.

Linear Tech added that the combination of dual architecture, tiny externals and a low profile exposed pad 3-by-3mm DFN package make the LTC3548 the most compact synchronous step-down solution available for dual output voltage rails. A leaded MSOP-10E package is also available.

The LTC3548EDD is available in a DFN-10 package, and the LTC3548EMSE is in a thermally enhanced MSOP package. Both devices are available from stock, with pricing for both starting at $2.60 each for 1,000-piece quantities.

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