55V, 1.2A Step down DC/DC converter

Its Burst Mode operation is designed to keep quiescent current under 2.8µA in no load standby conditions. The LT3991's 4.3 to 55V input voltage range makes it suitable for automotive and industrial applications. Its internal 1.7A switch can deliver up to 1.2A of continuous output current to voltages as low as 1.19V. The LT3991's Burst Mode operation offers ultralow quiescent current, making it well suited for applications such as automotive or industrial systems that demand always on operation and optimum battery life. Switching frequency is user programmable from 200kHz to 2MHz, enabling the designer to optimise efficiency while avoiding critical noise sensitive frequency bands. The combination of its 10lead 3 x 3mm DFN or thermally enhanced MSOP packages and high switching frequency keep external inductors and capacitors small, providing a compact, thermally efficient footprint. The LT3991 utilises a 1.7A, 440mOhm switch, with the necessary boost diode, oscillator, control and logic circuitry integrated into a single die. Low ripple Burst Mode operation is designed to maintain high efficiency at low output currents while keeping output ripple below 15mV^PK-PK. Its current mode topology is said to enable fast transient response and loop stability. Other features include a power good flag, soft start capability, external clock synchronisation and internal compensation.