Charger IC and its role in a portable power path
The MAX8903JETI+T is a 1-cell Li-Ion battery charger IC from the Smart Power Selector™ series, designed to manage charging from a USB input while powering the system load. It integrates an over-voltage protection block, so a fault on the input rail does not propagate to the battery or the system rail.
Key charging parametrics for the BOM
The charge current is programmable up to 2 A maximum, with a constant-current phase that the designer sets via an external resistor — the 2 A ceiling governs the thermal budget in the 28-TQFN package. Battery regulation voltage is 4.35 V, the termination voltage for a 1-cell Li-Ion stack; the charger enters constant-voltage mode at this threshold and holds it until the charge current tapers to the programmed termination level. Supply voltage rating is 16 V maximum, which covers the full USB bus-voltage range plus margin for hot-plug transients on the VBUS line. Programmable features include the charge current and a safety timer — the timer provides a backup termination if the battery fails to reach the regulation voltage within the set window, a standard safeguard for Li-Ion charging.
Compliance and procurement posture
ROHS3 compliant per the manufacturer's declaration, covering the full substance-restriction scope of the EU RoHS directive.