High Efficiency Step-Down DC/DC Converters with Internal Schottky Diode

The LTC1574 is a family of easy-to-use current mode DC/DC converters ideally suited for 9V to 5V, 5V to 3.3V and inverting operation. With an internal 0.9Ω switch (at a supply voltage of 12V) and a low forward drop Schottky diode. (0.45V typ at 200mA, TA=25°C), the LTC1574 requires only three external components to construct a complete high efficiency DC/DC converter.

Under no load condition the LTC1574 draws only 130µA. In shutdown, it draws a mere 2µA making this converter ideal for battery-powered applications. In dropout, the internal P-channel MOSFET switch is turned on continuously allowing the user to maximize the life of the battery source.

The maximum inductor current of the LTC1574 family is pin selectable to either 340mA or 600mA, optimizing efficiency for a wide range of applications. Operation up to 200kHz permits the use of small surface mount inductors and capacitors.

For applications requiring higher output current or ultrahigh efficiency, see the LTC1148 or LTC1265 data sheets. For detailed applications information, see the LTC1174 data sheet.

Applications

* Inverting Converters

* Step-Down Converters

* Memory Backup Supply

* Portable Instruments

* Battery-Powered Equipment

* Distributed Power Systems

* High Efficiency: Up to 94%

* Usable in Noise-Sensitive Products

* Peak Inductor Current Independent of Inductor Value

* Short-Circuit Protection

* Internal Low Forward Drop Schottky Diode

* Only Three External Components Required

* Wide VIN Range: 4V to 18.5V (Absolute Maximum)

* Low Dropout Operation

* Low-Battery Detector

* Pin Selectable Current Limit

* Internal 0.9Ω Power Switch: VIN < 11V

* Standby Current: 130µA

* Active Low Micropower Shutdown