Wide-input buck controller for high-temp environments
The LT3845EFE#TRPBF is a current-mode step-down (buck) DC/DC controller from Analog Devices, designed for applications requiring a 4V to 60V input supply — covering 12V and 24V industrial rails, automotive battery voltages including cold-crank and load-dump transients, and 48V telecom backplanes.
Synchronous rectification and fixed-frequency switching
Synchronous rectification is built in, which means the controller drives both the high-side and low-side external MOSFETs — eliminating the freewheeling diode and improving efficiency above 90% in typical 12V-to-3.3V or 5V conversions. The 300kHz fixed switching frequency keeps the inductor physically small while staying below the AM radio band, simplifying input filter design. Control features include Enable, Frequency Control, and Soft Start. The frequency control pin allows synchronization to an external clock or adjustment of the internal oscillator, useful for spreading EMI across multiple converters on the same board. Soft start limits inrush current during startup, preventing input rail droop.
Package and thermal interface
Housed in a 16-TSSOP with exposed pad, the package requires a thermal land pattern on the PCB to conduct heat from the die to the copper plane. Surface-mount assembly per JEDEC MSL-1 (implied by ROHS3 and standard Analog Devices handling) allows unlimited floor life at ≤30°C/85% RH before reflow — no bake needed for typical production runs.
It is suitable for both new designs and existing production BOMs without a migration plan. This covers global regulatory requirements for electronics placed on the EU, UK, and most Asian markets.