MAX8934: Dual-input linear charger safely charges a Li+ cell by adjusting charge rate and termination voltage according to temperature

31st March 2010
ES Admin
Maxim introduced the MAX8934, the industry's first dual-input linear charger with Smart Power Selector(TM) circuitry to implement the JEITA (Japan Electronics and Information Technology Industries Association) recommendations for safe charging over temperature. The MAX8934 monitors battery temperature and automatically adjusts the charge current and termination voltage to a safe level according to temperature. When external power is connected, the Smart Power Selector circuitry allows the system to operate with no battery or a deeply discharged battery, and automatically switches the system load from the battery.
All necessary current-sense circuitry and power switches for charging and switching the load between the battery and external power are integrated. This results in an ideal compact solution for one-cell, Li+-powered handheld devices such as smartphones, digital still cameras, media players, gaming systems, or GPS navigation systems.

The MAX8934 operates with either separate inputs for USB and AC adapter power, or from a single input that accepts both. The DC input's current limit is adjustable up to 2A; the USB input's current limit is adjustable to 1.5A*. Both DC and USB inputs support 100mA, 500mA, 1.5A, and USB-suspend modes. Charge current is adjustable up to 1.5A to support a wide range of battery capacities. Other features include a thermal regulation loop to prevent overheating, adaptive battery charging to prioritize support of system load over charge current, OVP (overvoltage protection), open-drain charge status and fault outputs, power-OK monitors, charge timers, and a battery thermistor monitor.

The MAX8934 is available in a space-saving, thermally enhanced, 4mm x 4mm, 28-pin TQFN package that is fully specified over the -40 degrees Celsius to +85 degrees Celsius temperature range. Prices start at $2.03 (1000-up, FOB USA). An evaluation kit is available to facilitate designs.

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