80V bidirectional buck-boost — the input range decides the system
The LT8708ILWE#PBF is an 80V bidirectional buck-boost controller from Analog Devices, built for systems where the input rail swings above and below the output. The 2.8V to 80V supply range covers multi-cell battery stacks, 12V/24V automotive nets with cold-crank dips, and industrial 48V rails — all without a pre-regulator. It regulates a single positive output using a 2-phase buck-boost topology with synchronous rectification, which means the low-side FETs also conduct — efficiency holds up across the full input-to-output ratio, not just in buck or boost mode alone.
Switching frequency and duty cycle — sizing the magnetics
A 100kHz design uses a larger inductor but keeps switching losses low; 400kHz shrinks the magnetics at the cost of higher FET gate-drive dissipation. The 80% max duty cycle caps the step-down ratio — at 5V input, the minimum achievable output is about 6.25V before the controller skips cycles. The 64-LQFP exposed pad package is the thermal interface for the controller's internal gate-drive losses. The PCB layout must connect the pad to a copper plane — the datasheet's recommended footprint and via pattern are not optional for full load operation at 125°C junction temperature.
Lifecycle and compliance — design-in safe, no EOL clock ticking
ROHS3 compliant, so it clears EU and global regulatory requirements without an exemption expiry. For a BOM that already uses the LT8708EUHG#PBF, the ILWE variant is the same silicon in a tray-packed LQFP instead of tube — the electrical ratings are identical, so no re-spin is needed. The only difference is the shipping medium and the package marking.