Power Electronics

Multi-cell Li-ion Charger Integrates LDO

Maxim Integrated Products has introduced the MAX8730, a low-cost battery-charger IC. The device charges three or four lithium-ion (Li+) cells in series at charge currents greater than 3.5 A. Analog inputs control input current limit, charge current and voltage. An integrated 3.3-V LDO supplies more than 20 mA of current to any external circuitry or ICs, such as a keyboard controller. A digital output is used to detect ac-adapter presence.

The new component provides 0.5%-accurate battery voltage regulation, which increases battery capacity and minimizes charging time. The device can be hardwired or controlled by a microprocessor to set the charging current or voltage. Based on the presence or absence of an ac adapter, the component uses two p-channel MOSFETs to automatically select the appropriate source for powering the system.

The part also features ac-adapter current limiting. The IC monitors the current drawn from the adapter and adjusts the charge current so that supplying the system load and the charger simultaneously does not overload the adapter. This important feature enables system operation with lower cost ac adapters.

The MAX8730 is packaged in a space-saving 28-pin QFN (5 mm × 5 mm), and also is available in a lead-free package. Prices start at $5.04 each for 1000-unit orders.

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