MILPITAS, CA – February 7, 2008 – Linear Technology announces the LT1939, a 2A, 25V step-down switching regulator and a linear controller in a 3mm x 3mm DFN package. The LT1939 operates from a VIN range of 3V to 25V, making it suitable for regulating power from a wide variety of sources, including protected automotive batteries, industrial supplies and unregulated wall adapters. Its 2.3A internal switch can deliver up to 2A of continuous output current at voltages as low as 0.8V. Switching frequency is user programmable and synchronizable from 250kHz to 2.2MHz, enabling designers to optimize efficiency while avoiding critical noise-sensitive frequency bands. The integrated LDO controller, combined with an NPN transistor, ensures very low noise output from the primary channel or and alternatively can be used as a second channel. The LT1939’s 3mm x 3mm DFN-12 package and high switching frequency, which keeps external capacitors and inductor small, provide a very compact, thermally efficient footprint.

The LT1939 utilizes a high efficiency 2.3A, 450mVCESAT switch with the necessary oscillator, control, logic circuitry and LDO controller integrated into a single die. Special design techniques enable high efficiency over a wide input voltage range while its current mode topology enables fast transient response and excellent loop stability. Other features include a power good flag and soft-start capability.

The LT1939EDD is priced starting at $3.05 each for 1,000-piece quantities. The LT1939IDD is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature and is priced at $3.66 each. Both versions are available from stock.

Summary of Features: LT19 39

• Wide Input Range: 3V to 25V

• Short-Circuit Protected Over Full Input Range

• 2A Output Current Capability

• Adjustable/Synchronizable Fixed Frequency Operation from 250kHz to 2.2MHz

• Soft-Start/Tracking Capability

• Output Adjustable Down to 0.8V

• Adjustable Linear Regulator/Driver with 13mA Output Capability

• Power Good Comparator with Complimentary Outputs

• Low Shutdown Current: 12uA

• Thermally Enhanced 3mm × 3mm DFN-12 Package