It uses synchronous rectification for high efficiency. The adjustable output can be set from a 0.782 V reference up to the input voltage.
Housed in a 16-lead MSOP with an exposed pad (16-MSOP-EP), the package measures 3.00 mm wide. The pad is on the bottom; a via array under it helps pull heat into the inner layers. The part ships in Tube form, not tape-and-reel, so plan for manual or tray-fed pick-and-place if your line is set up for reels.
Switching frequency and component sizing
A higher frequency shrinks the inductor and output capacitor but increases switching losses; a lower frequency improves efficiency at the cost of larger magnetics. The 2.2 MHz top end lets you keep the design above the AM radio band if needed for automotive EMC compliance.
For dual-sourcing, the closest functional peer is the LT8611EUDD#PBF, a 2.5 A buck with a 3.4 V minimum input and a 125°C temperature ceiling — the LT8609A's 150°C rating and 3 V minimum input give it an edge in high-temperature and low-input-voltage scenarios.