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Maxim Integrated Products has introduced a linear battery charger for Bluetooth headsets and portable devices that is compatible with the USB Battery Charging Specification, Revision 1.1. The new MAX8895 is equipped with automatic adapter detection for distinguishing between USB devices, USB chargers, and dedicated chargers. It also integrates a USB enumeration function that automatically negotiates with the USB host to optimise charging current without processor intervention. This eliminates the need for a separate microcontroller and system software, providing the industry's only stand-alone charging solution.
Smart Power Selector functionality provides a seamless distribution of power from the USB power input (Vbus) to the battery and system load. This allows simultaneous charging of the battery while powering the system, as well as operation of the portable device with a discharged battery or no battery. The battery also supplements Vbus when the system load exceeds the Vbus input current limit. The MAX8895 integrates a battery-disconnect switch, current-sense circuit, thermal-regulation circuitry, MOSFET pass elements, and overvoltage protection (OVP) up to 16V, providing an easy-to-implement, extremely compact charger solution. Flexible programming options include fast-charge current, termination current, and charge timer duration. It also supports adaptive battery charging, which reduces charge current when necessary to prevent the charge source from collapsing. Other features include a charge-status flag, charge-fault flag, power-OK monitor, battery thermistor monitor, timer for safe charging, and undervoltage lockout (UVLO). The MAX8895 is offered with two USB options, the MAX8895X (low speed) and the MAX8895Y (full speed), both of which operate from a 4.0V to 6.6V supply. Available in a tiny, 2.5mm x 2.5mm, 25-bump WLP (0.4mm pitch), the MAX8895 is fully specified over the -40 degrees Celsius to 85 degrees Celsius extended temperature range.
