80V bidirectional buck-boost controller, 2-phase synchronous
The LT8708ELWE#PBF is an 80V bidirectional buck-boost switching regulator controller from Analog Devices. It operates from a 2.8V to 80V supply rail, making it suitable for systems that must regulate through a wide input range, such as battery-backed supplies, automotive 12V/24V/48V rails, or industrial 24V-72V bus architectures. The part uses a 2-phase, single-output topology with synchronous rectification, achieving up to 80% duty cycle. Switching frequency is programmable from 100kHz to 400kHz, with clock synchronization input available to phase-lock the converter to an external clock, reducing system-level beat-frequency noise.
Supply range, temperature grade, and package fit
The 2.8V to 80V Vcc range covers the full spectrum from a deeply discharged 3-cell Li-ion battery (≈9V) through a 48V telecom rail to a 72V industrial bus, with margin on both ends. The positive output configuration and transistor driver output allow the controller to drive external N-channel MOSFETs for both buck and boost stages. The enable control feature allows the regulator to be gated by a system supervisor or power-good signal, sequencing the output rail on and off without an external load switch. The 80% maximum duty cycle limits the boost ratio — for a given input voltage, the output cannot exceed about 5× the input (theoretical limit), but practical designs stay well below that due to inductor and switch losses.
Active production, RoHS3, and sourcing posture
The closest peer is the LT8708EUHG#PBF, which shares the same silicon (same 2.8V-80V input, same frequency range, same 2-phase synchronous topology) but ships in a tube package instead of tray. The LT8708EUHG#PBF uses a 52-QFN package (7x8mm) versus the 64-LQFP-EP (10x10mm) — the pinout and footprint differ, so a board designed for one does not accept the other without layout changes.