The BQ24133 is a stand-alone switched-mode charger with power path selector. The device can operate from either a qualified adapter or supply system power from the battery. Dynamic Power Management (DPM) mode allows for a smaller adapter to be used effectively in systems with more dynamic system loads.

The BQ24133 device provides power path selector gate driver ACDRV/CMSRC on input NMOS pair ACFET (Q1) and RBFET (Q2), and BATDRV on a battery PMOS device (Q3). When the qualified adapter is present, the system is directly connected to the adapter. Otherwise, the system is connected to the battery. In addition, the power path prevents battery from boosting back to the input.

The BQ24133 features DPM to reduce the charge current when the input power limit is reached to avoid overloading the adapter. A highly accurate current-sense amplifier enables precise measurement of input current from adapter to monitor overall system power.

The total input current from an AC adapter or other DC sources is a function of the system supply current and the battery charging current. System current normally fluctuated as portions of the systems are powered up or down. Without DPM, the source must be able to supply the maximum system current and the maximum available charger input current simultaneously. By using DPM, the input current regulator reduces the charging current when the summation of system power and charge power exceeds the maximum input power. Therefore, the current capability of the AC adapter can be lowered, thus reducing system cost.

Although the BQ24133 is a stand-alone charger, external control circuitry can effectively be used to change pin settings such as ISET, ACSET, and enable Battery Learn mode to accommodated for dynamic charging conditions.