Charge profile and battery fit
The BD8665GW-E2: The BD8665GW- is a single-cell Li-Ion charger IC with a USB interface, targeting 8.4V battery packs — that is a 2-series stack (2S), common in portable medical devices, power tools, and handheld instrumentation where the system rail needs more than 4.2V. Short-circuit protection is integrated on the output, so the charge path shuts down before the battery or PCB trace can fault — one less external fuse or PTC to budget.
Housed in a 20-ball UCSP75M2 (2.2x2.2 mm) — a fine-pitch wafer-level CSP. The 0.5 mm ball pitch demands a controlled impedance layout and a stencil aperture that matches the ball diameter for reliable solder joint formation.
Temperature grade and supply rail
Operating temperature spans -30°C to 85°C ambient — enough margin for a device that sits near a warm battery pack in a sealed enclosure, but not rated for under-hood automotive or extended 105°C ambient. Maximum supply voltage is 5.5V, which aligns with USB VBUS (5V nominal). The charger can run directly from a USB port or a 5V wall adapter without an external LDO.