Maxim Integrated Products introduces the MAX8903A, a switch-mode DC-DC charger with Smart Power Selector circuitry. The charger employs a switching frequency of 4MHz typ. to minimize heat and charge time, while allowing the use of tiny external components. The 4mm x 4mm MAX8903A includes all power switches and current-sense circuitry required for charging and switching the load between battery and external power.

This device is optimized for rechargeable, 1-cell lithium-ion (Li+) batteries, making it ideal for smartphones, mobile internet devices, portable media players, portable navigation devices, digital still cameras, and ultra-mobile PCs. The MAX8903A can operate with either separate inputs for USB and AC-adapter power or from a single input that accepts both. When external power is connected, the Smart Power Selector circuitry allows the system to operate with no battery or a deeply discharged battery. It automatically switches the system load from the battery and makes the best use of limited USB or adapter power while charging the battery from input power not used by the system.

The converter on the DC input has a wide, 4.1V to 16V input range for direct charging from USB, AC-adapter, and car charger inputs; the dedicated USB input operates from 4.1V to 6.6V. The DC-input current limit is adjustable up to 2A, and both the DC and USB inputs support 100mA, 500mA, and USB suspend modes. Charge current is adjustable up to 2A to support a wide range of battery capacities. Other MAX8903A features include thermal regulation, overvoltage protection, charge-status and fault outputs, power-OK monitors, a battery thermistor monitor, and a charge timer.

The chip is available in a space-saving (4mm x 4mm), thermally enhanced, 28-pin TQFN package and is fully specified over the -40°C to +85°C extended temperature range. Prices start at $2.55 (1000-up, FOB USA). An evaluation kit is available.