Step-down dc/dc converter

Linear Technology has announced the "H-grade" version of the LT3680, a 3.5A, 36V step-down switching regulator with Burst Mode operation said to keep quiescent current under 75µA.

The LT3680 operates within a VIN range of 3.6 to 36V, making it suitable for load dump and cold crank conditions found in automotive applications. The H-grade version operates up to a junction temperature of 150°C, compared to the "E" and "I" versions' 125°C maximum junction temperature. All electrical specifications are identical for the E, I and H-grade versions. The H-grade devices are tested and guaranteed to the maximum junction temperature of 150°C, making them suitable for automotive and industrial applications which are subjected to high ambient temperatures. According to Linear, the LT3680's 4.6A internal switch can deliver up to 3.5A of continuous output current at voltages as low as 0.79V. The LT3680's Burst Mode operation is said to ensure ultralow quiescent current, suited for applications such as automotive or telecom systems, which demand always-on operation and optimum battery life. Switching frequency is user programmable from 250kHz to 2.4MHz, enabling designers to optimise efficiency while avoiding critical noise sensitive frequency bands. Its thermally enhanced MSOP-10E package and high switching frequency are designed to keep external inductors and capacitors small, providing a compact, thermally efficient footprint. Other features include external synchronisation (from 250kHz to 2MHz), a power good flag and soft-start capability.