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DC/DC integrates VLDO in a single package

Posted: 02 Feb 2007 ?? ?Print Version ?Bookmark and Share

Keywords:DC/DC? buck regulator? VLDO? Linear? power management?

Linear Technology has announced the LTC3541, a 500mA, high-efficiency, 2.25MHz synchronous buck regulator and a 300mA VLDO in a single package. The device provides two high-efficiency voltage rails from a single input requiring only a single inductor.

The synchronous buck regulator delivers up to 95 percent efficiency, whereas the VLDO output offers very low noise. The input voltage range of 2.7-5.5V makes the device suitable for single cell Li-ion/Polymer or multicell alkaline/NiCad/NiMH powered applications.

Compact footprint
The LTC3541 can generate output voltages as low as 0.8V from the buck regulator and 0.4V from the VLDO, enabling it to power the latest generation of MCUs. The buck regulator's 2.25MHz switching frequency and the VLDO design enable the utilization of tiny, low-cost externals, providing a very compact solution footprint for handheld applications.

All versions of the LTC3541 can be programmed via an external pin to have the synchronous buck power up independently or simultaneously with the VLDO. Additionally, when both the synchronous switcher and the VLDO are enabled, an automatic start-up sequencing feature brings up either the switcher or the VLDO in a specific order.

The LTC3541 and LTC3541-2 have an automatic start-up feature that brings the buck output into regulation prior to enabling the VLDO regulator. Alternatively, the LTC3541-1 and LTC3541-3 bring the VLDO into regulation prior to enabling the switching regulator. The VLDO can either be operated directly from the output of the switching regulator, for maximum efficiency, or from a separate input from 0.9-4.1V.

Maximum battery run-time
An automatic Burst Mode feature reduces quiescent current in the switcher to only 85?A, thereby maximizing battery run-time. For applications that are particularly noise sensitive, the Burst Mode feature can be disabled and replaced with either a pulse skipping or continuous switching operation. Other features include a power-good output and over-temperature protection.

All versions of the LTC3541 are available from stock in a 10-Lead 3-by-3mm DFN package. Pricing starts at $1.95 each in 1,000-piece quantities.

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Related Datasheets
Part Number Description Category
? LTC3541 High Efficiency Buck + VLDO Regulator ICs, Interface



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