Package and board-fit for the STC3115IJT
The STC3115IJT ships in a 10-WFBGA, CSPBGA package with a supplier device package of 10-CSP measuring 1.4x2.04 mm. This 10-ball wafer-level chip-scale package demands a fine-pitch PCB layout with controlled solder-paste stencil aperture for reliable BGA attachment.
What the I²C battery monitor does on the BOM
This is a battery gas gauge — the STC3115IJT tracks charge and discharge in Li-ion cells, reporting capacity data over an I²C interface to a host microcontroller. The OptimGauge™ series is STMicroelectronics' family for coulomb-counting and voltage-based fuel gauging in portable designs. Because the fuel gauge communicates over I²C, the host reads remaining capacity and voltage without dedicated ADC channels — the bus shares the same two wires as other I²C peripherals on the board.
No official successor or second-source cross-reference is listed. The closest peer within the OptimGauge family is the STC3115IQT, which shares the same function and I²C interface but uses a different package variant — the IQT is a TSSOP-14, not a CSP, so the PCB footprint and reflow profile differ.