Buck-boost controller for wide-input, single-inductor regulation
The LTC3785EUF-1#PBF from Analog Devices is a current-mode synchronous buck-boost switching regulator controller that regulates a positive output voltage from an input that can be above, below, or equal to the output. It operates from a 2.7 V to 10 V supply and switches at a user-programmable frequency between 100 kHz and 1 MHz, allowing the designer to optimise the power-stage for efficiency or inductor size. The controller drives external N-channel MOSFETs in a single-inductor topology, with synchronous rectification built in to maintain efficiency at low output voltages. Control features include current limiting, enable, and soft start. The part is supplied in a 24-QFN (4x4 mm) package and is rated for the industrial temperature range of -40°C to 85°C.
Switching frequency and inductor sizing
The switching frequency is set by an external resistor to ground and can be synchronised to an external clock within the 100 kHz to 1 MHz range.
Synchronous rectification and efficiency
Synchronous rectification eliminates the forward drop of a Schottky diode by replacing it with a second N-channel MOSFET driven by the controller.
Active lifecycle and ROHS3 compliance
It is ROHS3 compliant, meaning it contains no restricted substances above the exemption thresholds, including lead, mercury, cadmium, and the four phthalates. This part can be specified into new designs without obsolescence risk and meets the material-restriction requirements for EU and global markets.