85 V boost ceiling — what it buys the design
The TPS61391RTER: The 85 V output ceiling powers avalanche photodiode bias, MEMS driver supplies, or LCD backlight strings. The 700 kHz fixed switching frequency keeps the inductor small, but the non-synchronous topology means the external Schottky diode adds a conduction loss term that matters at high duty cycles.
Input range and output adjust — BOM-fit detail
Minimum input is 2.5 V, so a single Li-ion cell near end-of-discharge still keeps the regulator running. Maximum input is 5.5 V. The output is adjustable from a 20 V minimum up to 85 V via a resistor divider on the FB pin. The 16-WQFN (3x3 mm) package with exposed pad demands a thermal via array under the pad to keep RθJA below 40°C/W; a 2-layer board with 1 oz copper and four vias is marginal for continuous 85 V at 50 mA.
Sourcing posture — active, no imminent end-of-life
ROHS3 compliant. Sourced to order against BOM quantities — no stock-holding claim, availability confirmed at quote time.