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Intelligent Li-ion charging

NXP’s ISP1704 and ISP1601 are USB-battery-charger-detection chips for mobile-phone designs. They detect and differentiate between a dedicated USB charger, a USB Host Charger and a USB Host when charging a mobile-phone battery. The mechanism is in accordance with recently introduced regulations for the sale of mobile phones in China as well as the USB Implementers Forum’s (USB-IF) Battery Charging Specification Rev. 1.0. Benefits, NXP says, include faster charging and longer battery life; the features are invoked automatically whenever the consumer uses the USB connector in a mobile phone. The system has information to intelligently charge a battery by determining the level of charging current that it is able to draw, based on the type of USB connection available. Recently, USB 2.0 specifications prevailed and require that when a portable device is attached to a USB host or hub, the peak supply capacity be limited to 500 mA. The new specs from the USB-IF now permit devices to draw current in excess of the USB 2.0 requirements and call for portable devices to be able to distinguish between a high-current wall charger (up to 1.8A), a USB host or hub charger (up to 1.5A), and a standard USB host or hub (up to 500 mA).

NXP says that the ISP1704 is the first high-speed USB OTG ULPI transceiver to also offer an integrated batterycharger- detection function. It transmits and receives USB data at high-speed (480 Mbit/sec), full-speed (12 Mbit/sec) and low-speed (1.5 Mbit/sec) rates. The ISP1601 is a dedicated USB-batterycharger- detection IC with a chip-scalepackage footprint of less than 2 mm².

NXP, www.nxp.com