20-WLP package and board-fit
The MAX8971EWP+T ships in a 20-WFBGA, WLBGA package with a supplier device package size of 20-WLP (1.62x2.18 mm). This is a fine-pitch wafer-level package — the 20 balls are arrayed on the bottom side with no exposed paddle. The board requires a solder-mask-defined pad per ball, and the 1.62x2.18 mm footprint leaves minimal room for decoupling between the balls; place the 0402 bypass caps on the opposite side of the board, directly under the package via a micro-via-in-pad stack-up.
1.55A single-cell Li-Ion charge profile
This is a single-cell Li-Ion charger with a battery pack voltage of 4.2 V and a maximum charge current of 1.55 A. The charge current is constant and programmable via the I²C interface — the host sets the current level, and the charger holds it until the cell reaches 4.2 V, then transitions to constant-voltage taper. The 1.55 A ceiling suits a 1500–2000 mAh cell charged at roughly 1C; for a smaller cell, program the current down to avoid exceeding the cell's charge rate. The USB interface allows the charger to negotiate input current limits from a USB host or dedicated charging port.
Fault protection and temperature range
Fault protection covers overvoltage and reverse battery conditions — the charger blocks charging if the input exceeds the safe limit or if the battery is connected backwards.