GENERAL DESCRIPTION
High efficiency is achieved through use of a constant off-time step-down topology with synchronous rectification. In addition to support of the Smart-Battery-Charger Specifications Rev 1.1, the MAX1535B/MAX1535C/ MAX1535D include additional features. This enables the user to reduce the cost of the AC adapter. The MAX1535B/MAX1535C/ MAX1535D provide a digital output that indicates the presence of an AC adapter. Based on the presence or absence of the AC adapter, the MAX1535B/MAX1535C/ MAX1535D automatically select the appropriate source for supplying power to the system by controlling two external p-channel MOSFETs. Under system control, the MAX1535B/MAX1535C/MAX1535D allow the battery to undergo a relearning or conditioning cycle in which the battery is completely discharged through the system load and then recharged. The MAX1535B/MAX1535C/MAX1535D are capable of charging 2, 3, or 4 lithium-ion (Li+) cells in series, providing charge currents as high as 8A. The DC-DC converter in the MAX1535B/MAX1535C/MAX1535D uses a highside p-channel switch with an n-channel synchronous rectifier.