Battery charger handles lead acid and Li-ion

An integrated, high voltage synchronous step down battery charger controller from Linear Technology uses temperature compensated three and four stage algorithms to charge 12V and 24V lead acid batteries. The part can also charge a multicell lithium-based battery stack with float voltages near to the input supply.

The LTC4013, which uses N-channel MOSFETs for high efficiency charging, features a battery charge voltage range of 0 to 60V. The main charging features of the product can be adjusted using pin-strap configurations and programming resistors, enabling the user to select between several predefined charging algorithms depending on battery chemistry.

For lead-acid battery types, the LTC4013 supports multiple charging stages, including float, programmable-timed absorption and equalisation. Each charge voltage includes adjustable temperature compensation. For Li-ion/polymer cells, the device offers a constant-current/constant-voltage charging algorithm.

The SYNC input provides the ability to synchronise the switching frequency to an external clock to avoid noise in a particular frequency range or to target noise filters to a specific frequency. Other features include an external input MOSFET driver to avoid battery discharge during an input supply short, two open-drain status pins and an ISMON pin that provides analogue information about charge current.

The LTC4013 is housed in a 28 lead QFN package measuring 4 x 5mm, with an exposed metal pad for thermal management. According to Linear, E and I grade versions of the part are suited to temperatures ranging fron -40 to 125°C.

Graham Pitcher

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