LTC3541 Series

The LTC3541-2 combines a synchronous buck DC/DC converter with a very low dropout linear regulator (VLDO™regulator) and internal feedback resistor networks to provide two output voltages from a single input voltage with minimal external components. When configured for dual output operation, the LTC3541-2’s auto start-up feature will bring the 1.875V buck output into regulation in a controlled manner, prior to enabling the 1.5V VLDO output without the need for external pin control. The 1.5V VLDO/linear regulator output prior to 1.875V buck output sequencing may also be obtained via external pin control. The input voltage range is ideally suited for Li-Ion battery applications powering sub-3.3V logic from 5V or 3.3V rails.The synchronous buck converter provides a high efficiency output, typically 90%. It can provide up to 500mA of output current while switching at 2.25MHz, allowing the use of small surface mount inductors and capacitors. A mode select pin allows Burst Mode operation to be enabled for higher efficiency at light load currents, or disabled for lower noise, constant frequency operation.The VLDO regulator provides a low noise, low voltage output capable of providing up to 300mA of output current using only a 2.2μF ceramic capacitor. The input supply voltage of the VLDO regulator (LVIN) may come from the buck regulator output or a separate supply.OptionsVout Switcher (V)Vout VLDOAuto Start Up SequencingLTC3541Adj. down to 0.8VAdj. down to 0.4VSwitcher, then VLDOLTC3541-1Adj. down to 0.8VAdj down to 0.4VVLDO, then switcherLTC3541-21.875V fixed1.5V fixedSwitcher, then VLDOLTC3541-31.8V fixed1.575 fixedVLDO, then switcherApplicationsDigital CamerasCellular PhonesPC CardsWireless and DSL ModemsOther Portable Power Systems