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.