Chips charge lithium cells with safety

Fully integrated devices combine several key charge-management and safety features in a single chip for reliable charging of high-capacity single-cell Li-ion and Li-polymer batteries.

New from Microchip, the MCP73833 and MCP73834 are single-cell high-current (1A), Li-ion/Li-polymer linear charge-management controllers.

These fully integrated devices combine several key charge-management and safety features in a single chip for reliable charging of high-capacity single-cell Li-ion and Li-polymer batteries.

By including a pass transistor, current-sense and reverse-discharge protection on a single chip, the MCP73833/4 charge-management controllers eliminate the need for external components.

Multiple combinations of key charging parameters, including pre-conditioning current threshold and ratio, charge-termination threshold and recharge threshold ratio are available, meaning the devices provide standard product support for a variety of high-current Li-ion/Li-polymer charging applications.

In addition, with a high charging current of up to 1A and support for multiple regulated output voltages (4.2, 4.35, 4.4 and 4.5V), the devices can be used with various generations of Lithium battery technology.

Safety features on the new devices to prevent overcharging and overheating include charge timers, battery-temperature feedback and thermal-current regulation.

The charge timer shuts the charger off if a charge is not terminated before timeout is reached.

The battery-temperature feedback reduces the charge current if the battery's temperature reaches the limit of safety and the thermal-current regulation feature decreases the charge current if the charge-controller itself reaches its thermal limits.

Device-specific features include a power-good output on the MCP73833 and a timer-enable input on the MCP73834.

Both devices also offer a low dropout regulator (LDO) test mode that enables application system test even in the absence of a battery; and both feature two status outputs to provide the user with additional information about the state of the charge-controller.

To support development, Microchip offers an MCP73833 evaluation board.

The MCP73833/4 charge-management controllers are available in 10-pin MSOP and thermally efficient 3 x 3mm DFN packages.

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